pubmed_id
stringlengths 39
43
| abstract
stringlengths 3
18k
|
|---|---|
http://www.ncbi.nlm.nih.gov/pubmed/10592229
|
1. Nucleic Acids Res. 2000 Jan 1;28(1):214-8. doi: 10.1093/nar/28.1.214.
Kabat database and its applications: 30 years after the first variability plot.
Johnson G(1), Wu TT.
Author information:
(1)Department of Biochemistry, Northwestern University, Evanston, IL 60208, USA.
The Kabat Database was initially started in 1970 to determine the combining site
of antibodies based on the available amino acid sequences at that time. Bence
Jones proteins, mostly from human, were aligned, using the now-known Kabat
numbering system, and a quantitative measure, variability, was calculated for
every position. Three peaks, at positions 24-34, 50-56 and 89-97, were
identified and proposed to form the complementarity determining regions (CDR) of
light chains. Subsequently, antibody heavy chain amino acid sequences were also
aligned using a different numbering system, since the locations of their CDRs
(31-35B, 50-65 and 95-102) are different from those of the light chains. CDRL1
starts right after the first invariant Cys 23 of light chains, while CDRH1 is
eight amino acid residues away from the first invariant Cys 22 of heavy chains.
During the past 30 years, the Kabat database has grown to include nucleotide
sequences, sequences of T cell receptors for antigens (TCR), major
histocompatibility complex (MHC) class I and II molecules and other proteins of
immunological interest. It has been used extensively by immunologists to derive
useful structural and functional information from the primary sequences of these
proteins. An overall view of the Kabat Database and its various applications are
summarized here. The Kabat Database is freely available at
http://immuno.bme.nwu.edu
DOI: 10.1093/nar/28.1.214
PMCID: PMC102431
PMID: 10592229 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/12182069
|
1. Yi Chuan Xue Bao. 2002;29(3):189-95.
A method for constructing reshaping single-domain antibody.
Cheng JL(1), Wang XB, Zhang Z, Liu J, Yao XS, Huang HL.
Author information:
(1)Institute of Genetics and Developmental Biology, Chinese Academy of Sciences,
Beijing 100101, China.
The aim of this research was to demonstrate a novel and practical method for
constructing reshaping Single-domain antibodies. Different from other methods,
our method does not need to model the configuration of antibodies with specific
sequences to determine the sequences of human acceptor FRs and then determine
which amino acid residues in human acceptor FRs should be substituted. Most
importantly, reshaping and enhancing the antigen binding affinity shared one
procedure at the same time. Using this method, the reshaping anti-CD28
single-domain antibodies were constructed. According to the amino acid sequence
of a mouse anti-human CD28 monoclonal antibody VH, two most homologous sequences
of human antibodies were selected from GenBank and one of them was used as a
main framework region for constructing the reshaping antibody. Before the
original mouse antibody CDRs were inserted into the human acceptor FRs, some
amino acid residues which were different from those of the original mouse
antibody in the corresponding positions of the human acceptor FRs were
determined or alternatively mutated by their conservative properties in Kabat
classification. When the synthesized nucleotide fragments in different length
were spliced by overlap PCR into the entire reshaping genes, Taq DNA polymerase
and high Mg2+ concentration were used to introduce more mutation in FRs and CDRs
randomly. A phage library was constructed using these PCR products and several
reshaping Single-domain antibodies with high antigen binding affinity were
selected after three rounds of panning. Two of them were expressed in E. coli
BL21 (DE3). The antigen-binding affinity of refolded proteins was still in a
high level measured by ELISA. These results suggested that this method was
feasible and efficient for constructing reshaping Single-domain antibodies.
PMID: 12182069 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/11459824
|
1. Genes Dev. 2001 Jul 15;15(14):1753-8. doi: 10.1101/gad.905701.
Arabidopsis cmt3 chromomethylase mutations block non-CG methylation and
silencing of an endogenous gene.
Bartee L(1), Malagnac F, Bender J.
Author information:
(1)Department of Biochemistry and Molecular Biology, Bloomberg School of Public
Health, Johns Hopkins University, Baltimore, Maryland 21205, USA.
Plants maintain cytosine methylation at CG and non-CG residues to control gene
expression and genome stability. In a screen for Arabidopsis mutants that alter
methylation and silencing of a densely methylated endogenous reporter gene, we
recovered 11 loss-of-function alleles in the CMT3 chromomethylase gene. The cmt3
mutants displayed enhanced expression and reduced methylation of the reporter,
particularly at non-CG cytosines. CNG methylation was also reduced at repetitive
centromeric sequences. Thus, CMT3 is a key determinant for non-CG methylation.
The lack of CMT homologs in animal genomes could account for the observation
that in contrast to plants, animals maintain primarily CG methylation.
DOI: 10.1101/gad.905701
PMCID: PMC312734
PMID: 11459824 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/24550830
|
1. Front Pharmacol. 2014 Jan 27;5:5. doi: 10.3389/fphar.2014.00005. eCollection
2014.
The role of CaMKII regulation of phospholamban activity in heart disease.
Mattiazzi A(1), Kranias EG(2).
Author information:
(1)Facultad de Medicina, Centro de Investigaciones Cardiovasculares, Conicet La
Plata-Universidad Nacional de La Plata La Plata, Argentina.
(2)Department of Pharmacology and Cell Biophysics, College of Medicine,
University of Cincinnati Cincinnati, OH, USA.
Phospholamban (PLN) is a phosphoprotein in cardiac sarcoplasmic reticulum (SR)
that is a reversible regulator of the Ca(2) (+)-ATPase (SERCA2a) activity and
cardiac contractility. Dephosphorylated PLN inhibits SERCA2a and PLN
phosphorylation, at either Ser(16) by PKA or Thr(17) by Ca(2)
(+)-calmodulin-dependent protein kinase (CaMKII), reverses this inhibition.
Through this mechanism, PLN is a key modulator of SR Ca(2) (+) uptake, Ca(2) (+)
load, contractility, and relaxation. PLN phosphorylation is also the main
determinant of β1-adrenergic responses in the heart. Although phosphorylation of
Thr(17) by CaMKII contributes to this effect, its role is subordinate to the
PKA-dependent increase in cytosolic Ca(2) (+), necessary to activate CaMKII.
Furthermore, the effects of PLN and its phosphorylation on cardiac function are
subject to additional regulation by its interacting partners, the anti-apoptotic
HAX-1 protein and Gm or the anchoring unit of protein phosphatase 1. Regulation
of PLN activity by this multimeric complex becomes even more important in
pathological conditions, characterized by aberrant Ca(2) (+)-cycling. In this
scenario, CaMKII-dependent PLN phosphorylation has been associated with
protective effects in both acidosis and ischemia/reperfusion. However, the
beneficial effects of increasing SR Ca(2) (+) uptake through PLN phosphorylation
may be lost or even become deleterious, when these occur in association with
alterations in SR Ca(2) (+) leak. Moreover, a major characteristic in human and
experimental heart failure (HF) is depressed SR Ca(2) (+) uptake, associated
with decreased SERCA2a levels and dephosphorylation of PLN, leading to decreased
SR Ca(2) (+) load and impaired contractility. Thus, the strategy of altering
SERCA2a and/or PLN levels or activity to restore perturbed SR Ca(2) (+) uptake
is a potential therapeutic tool for HF treatment. We will review here the role
of CaMKII-dependent phosphorylation of PLN at Thr(17) on cardiac function under
physiological and pathological conditions.
DOI: 10.3389/fphar.2014.00005
PMCID: PMC3913884
PMID: 24550830
|
http://www.ncbi.nlm.nih.gov/pubmed/20110242
|
1. Jpn J Clin Oncol. 2010 Jun;40(6):508-12. doi: 10.1093/jjco/hyp195. Epub 2010
Jan 27.
Clinical utility of the 70-gene MammaPrint profile in a Japanese population.
Ishitobi M(1), Goranova TE, Komoike Y, Motomura K, Koyama H, Glas AM, van Lienen
E, Inaji H, Van't Veer LJ, Kato K.
Author information:
(1)Department of Breast and Endocrine Surgery, Osaka Medical Center for Cancer
and Cardiovascular Diseases, Osaka, Japan.
OBJECTIVE: van't Veer and colleagues developed a 70-gene prognosis profile known
as MammaPrint to identify breast cancer patients who were at low risk of
developing metastases. We evaluated the prognostic value of the 70-gene
MammaPrint profile in Japanese women with node-negative breast cancer.
METHODS: Frozen tumour samples from 102 eligible node-negative breast cancer
patients aged 70 or younger were characterized with the MammaPrint array. The
patients were treated with breast-conserving therapy or mastectomy with axillary
lymph node dissection between December 1998 and August 2001. About 73 percent
received adjuvant hormonal therapy and 28 percent received adjuvant
chemotherapy. The gene expression profiles obtained by MammaPrint classified the
patients as high- or low-genomic risk. The median follow-up was 7.1 years.
RESULTS: Among the 102 patients, 20 (20%) were classified as low-genomic risk
and 82 (80%) were classified as high-genomic risk. The probability of distant
metastasis-free survival at five years was 100% for the low-risk group and 94%
for the high-risk group.
CONCLUSIONS: The 70-gene MammaPrint prognosis profile accurately identified
Japanese breast cancer patients at low risk of developing recurrences. In fact,
100% of the individuals in the low-risk category remained metastasis-free for
the duration of the observation period.
DOI: 10.1093/jjco/hyp195
PMID: 20110242 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/23533627
|
1. PLoS One. 2013;8(3):e59496. doi: 10.1371/journal.pone.0059496. Epub 2013 Mar
22.
The Drosophila melanogaster CHD1 chromatin remodeling factor modulates global
chromosome structure and counteracts HP1a and H3K9me2.
Bugga L(1), McDaniel IE, Engie L, Armstrong JA.
Author information:
(1)W.M. Keck Science Department, Claremont McKenna College, Pitzer College,
Scripps College, Claremont, California, United States of America.
CHD1 is a conserved chromatin remodeling factor that localizes to active genes
and functions in nucleosome assembly and positioning as well as histone
turnover. Mouse CHD1 is required for the maintenance of stem cell pluripotency
while human CHD1 may function as a tumor suppressor. To investigate the action
of CHD1 on higher order chromatin structure in differentiated cells, we examined
the consequences of loss of CHD1 and over-expression of CHD1 on polytene
chromosomes from salivary glands of third instar Drosophila melanogaster larvae.
We observed that chromosome structure is sensitive to the amount of this
remodeler. Loss of CHD1 resulted in alterations of chromosome structure and an
increase in the heterochromatin protein HP1a, while over-expression of CHD1
disrupted higher order chromatin structure and caused a decrease in levels of
HP1a. Over-expression of an ATPase inactive form of CHD1 did not result in
severe chromosomal defects, suggesting that the ATPase activity is required for
this in vivo phenotype. Interestingly, changes in CHD1 protein levels did not
correlate with changes in the levels of the euchromatin mark H3K4me3 or
elongating RNA Polymerase II. Thus, while CHD1 is localized to transcriptionally
active regions of the genome, it can function to alter the levels of HP1a,
perhaps through changes in methylation of H3K9.
DOI: 10.1371/journal.pone.0059496
PMCID: PMC3606111
PMID: 23533627 [Indexed for MEDLINE]
Conflict of interest statement: Competing Interests: The authors have declared
that no competing interests exist.
|
http://www.ncbi.nlm.nih.gov/pubmed/17322368
|
1. Am J Pathol. 2007 Mar;170(3):818-29. doi: 10.2353/ajpath.2007.060547.
Macrophage depletion impairs wound healing and increases left ventricular
remodeling after myocardial injury in mice.
van Amerongen MJ(1), Harmsen MC, van Rooijen N, Petersen AH, van Luyn MJ.
Author information:
(1)University Medical Center Groningen, University of Groningen, Groningen, The
Netherlands. m.van.amerongen@med.umcg.nl
Macrophages have been suggested to be beneficial for myocardial wound healing.
We investigated the role of macrophages in myocardial wound healing by
inhibition of macrophage infiltration after myocardial injury. We used a murine
cryoinjury model to induce left ventricular damage. Infiltrating macrophages
were depleted during the 1st week after cryoinjury by serial intravenous
injections of clodronate-containing liposomes. After injury, the presence of
macrophages, which secreted high levels of transforming growth factor-beta and
vascular endothelial growth factor-A, led to rapid removal of cell debris and
replacement by granulation tissue containing inflammatory cells and blood
vessels, followed by myofibroblast infiltration and collagen deposition. In
macrophage-depleted hearts, nonresorbed cell debris was still observed 4 weeks
after injury. Secretion of transforming growth factor-beta and vascular
endothelial growth factor-A as well as neovascularization, myofibroblast
infiltration, and collagen deposition decreased. Moreover, macrophage depletion
resulted in a high mortality rate accompanied by increased left ventricular
dilatation and wall thinning. In conclusion, infiltrating macrophage depletion
markedly impairs wound healing and increases remodeling and mortality after
myocardial injury, identifying the macrophage as a key player in myocardial
wound healing. Based on these findings, we propose that increasing macrophage
numbers early after myocardial infarction could be a clinically relevant option
to promote myocardial wound healing and subsequently to reduce remodeling and
heart failure.
DOI: 10.2353/ajpath.2007.060547
PMCID: PMC1864893
PMID: 17322368 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/12151602
|
1. Proc Natl Acad Sci U S A. 2002 Dec 10;99 Suppl 4(Suppl 4):16491-8. doi:
10.1073/pnas.162371599. Epub 2002 Jul 31.
Locus-specific control of asymmetric and CpNpG methylation by the DRM and CMT3
methyltransferase genes.
Cao X(1), Jacobsen SE.
Author information:
(1)Department of Molecular, Cell, and Developmental Biology, University of
California, Los Angeles 90095-1606, USA.
Many plant, animal, and fungal genomes contain cytosine DNA methylation in
asymmetric sequence contexts (CpHpH, H = A, T, C). Although the enzymes
responsible for this methylation are unknown, it has been assumed that
asymmetric methylation is maintained by the persistent activity of de novo
methyltransferases (enzymes capable of methylating previously unmodified DNA).
We recently reported that the DOMAINS REARRANGED METHYLASE (DRM) genes are
required for de novo DNA methylation in Arabidopsis thaliana because drm1 drm2
double mutants lack the de novo methylation normally associated with transgene
silencing. In this study, we have used bisulfite sequencing and Southern blot
analysis to examine the role of the DRM loci in the maintenance of asymmetric
methylation. At some loci, drm1 drm2 double mutants eliminated all asymmetric
methylation. However, at the SUPERMAN locus, asymmetric methylation was only
completely abolished in drm1 drm2 chromomethylase 3 (cmt3) triple mutant plants.
drm1 drm2 double mutants also showed a strong reduction of CpNpG (n = A, T, C,
or G) methylation at some loci, but not at others. The drm1 drm2 cmt3 triple
mutant plants did not affect CpG methylation at any locus tested, suggesting
that the primary CpG methylases are encoded by the MET1 class of genes. Although
neither the drm1 drm2 double mutants nor the cmt3 single mutants show
morphological defects, drm1 drm2 cmt3 triple mutant plants show pleiotropic
effects on plant development. Our results suggest that the DRM and CMT3 genes
act in a partially redundant and locus-specific manner to control asymmetric and
CpNpG methylation.
DOI: 10.1073/pnas.162371599
PMCID: PMC139913
PMID: 12151602 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/23157214
|
1. BMC Biochem. 2012 Nov 17;13:24. doi: 10.1186/1471-2091-13-24.
A standard numbering scheme for thiamine diphosphate-dependent decarboxylases.
Vogel C(1), Widmann M, Pohl M, Pleiss J.
Author information:
(1)Institute of Technical Biochemistry, University of Stuttgart, Allmandring 31,
Stuttgart, 70569, Germany.
BACKGROUND: Standard numbering schemes for families of homologous proteins allow
for the unambiguous identification of functionally and structurally relevant
residues, to communicate results on mutations, and to systematically analyse
sequence-function relationships in protein families. Standard numbering schemes
have been successfully implemented for several protein families, including
lactamases and antibodies, whereas a numbering scheme for the structural family
of thiamine-diphosphate (ThDP) -dependent decarboxylases, a large subfamily of
the class of ThDP-dependent enzymes encompassing pyruvate-, benzoylformate-,
2-oxo acid-, indolpyruvate- and phenylpyruvate decarboxylases, benzaldehyde
lyase, acetohydroxyacid synthases and
2-succinyl-5-enolpyruvyl-6-hydroxy-3-cyclohexadiene-1-carboxylate synthase
(MenD) is still missing.Despite a high structural similarity between the members
of the ThDP-dependent decarboxylases, their sequences are diverse and make a
pairwise sequence comparison of protein family members difficult.
RESULTS: We developed and validated a standard numbering scheme for the family
of ThDP-dependent decarboxylases. A profile hidden Markov model (HMM) was
created using a set of representative sequences from the family of
ThDP-dependent decarboxylases. The pyruvate decarboxylase from S. cerevisiae
(PDB: 2VK8) was chosen as a reference because it is a well characterized enzyme.
The crystal structure with the PDB identifier 2VK8 encompasses the structure of
the ScPDC mutant E477Q, the cofactors ThDP and Mg(2+) as well as the substrate
analogue (2S)-2-hydroxypropanoic acid. The absolute numbering of this reference
sequence was transferred to all members of the ThDP-dependent decarboxylase
protein family. Subsequently, the numbering scheme was integrated into the
already established Thiamine-diphosphate dependent Enzyme Engineering Database
(TEED) and was used to systematically analyze functionally and structurally
relevant positions in the superfamily of ThDP-dependent decarboxylases.
CONCLUSIONS: The numbering scheme serves as a tool for the reliable sequence
alignment of ThDP-dependent decarboxylases and the unambiguous identification
and communication of corresponding positions. Thus, it is the basis for the
systematic and automated analysis of sequence-encoded properties such as
structural and functional relevance of amino acid positions, because the
analysis of conserved positions, the identification of correlated mutations and
the determination of subfamily specific amino acid distributions depend on
reliable multisequence alignments and the unambiguous identification of the
alignment columns. The method is reliable and robust and can easily be adapted
to further protein families.
DOI: 10.1186/1471-2091-13-24
PMCID: PMC3534367
PMID: 23157214 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/21150311
|
1. Epigenetics. 2011 Mar;6(3):344-54. doi: 10.4161/epi.6.3.14242. Epub 2011 Mar
1.
Identification of genes required for de novo DNA methylation in Arabidopsis.
Greenberg MV(1), Ausin I, Chan SW, Cokus SJ, Cuperus JT, Feng S, Law JA, Chu C,
Pellegrini M, Carrington JC, Jacobsen SE.
Author information:
(1)Department of Molecular, Cell and Developmental Biology, University of
California Davis, USA.
De novo DNA methylation in Arabidopsis thaliana is catalyzed by the
methyltransferase DRM2, a homolog of the mammalian de novo methyltransferase
DNMT3. DRM2 is targeted to DNA by small interfering RNAs (siRNAs) in a process
known as RNA-directed DNA Methylation (RdDM). While several components of the
RdDM pathway are known, a functional understanding of the underlying mechanism
is far from complete. We employed both forward and reverse genetic approaches to
identify factors involved in de novo methylation. We utilized the FWA transgene,
which is methylated and silenced when transformed into wild-type plants, but
unmethylated and expressed when transformed into de novo methylation mutants.
Expression of FWA is marked by a late flowering phenotype, which is easily
scored in mutant versus wild-type plants. By reverse genetics we discovered the
requirement for known RdDM effectors AGO6 and NRPE5a for efficient de novo
methylation. A forward genetic approach uncovered alleles of several components
of the RdDM pathway, including alleles of clsy1, ktf1, and nrpd/e2, which have
not been previously shown to be required for the initial establishment of DNA
methylation. Mutations were mapped and genes cloned by both traditional and
whole genome sequencing approaches. The methodologies and the mutant alleles
discovered will be instrumental in further studies of de novo DNA methylation.
DOI: 10.4161/epi.6.3.14242
PMCID: PMC3092683
PMID: 21150311 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/16305737
|
1. Immunome Res. 2005 Sep 20;1:3. doi: 10.1186/1745-7580-1-3.
IMGT, the international ImMunoGeneTics information system: a standardized
approach for immunogenetics and immunoinformatics.
Lefranc MP(1).
Author information:
(1)IMGT, the international ImMunoGeneTics information system, Université
Montpellier II, Institut Universitaire de France, Laboratoire d'ImmunoGénétique
Moléculaire LIGM, UPR CNRS 1142, Montpellier, France. lefranc@ligm.igh.cnrs.fr
IMGT, the international ImMunoGeneTics information system http://imgt.cines.fr,
was created in 1989 by the Laboratoire d'ImmunoGénétique Moléculaire (LIGM)
(Université Montpellier II and CNRS) at Montpellier, France. IMGT is a high
quality integrated knowledge resource specialized in immunoglobulins (IG), T
cell receptors (TR), major histocompatibility complex (MHC) of human and other
vertebrates, and related proteins of the immune system (RPI) of any species
which belong to the immunoglobulin superfamily (IgSF) and to the MHC superfamily
(MhcSF). IMGT consists of five databases, ten on-line tools and more than 8,000
HTML pages of Web resources. IMGT provides a common access to standardized data
from genome, genetics, proteome and three-dimensional structures. The accuracy
and the consistency of IMGT data are based on IMGT-ONTOLOGY, a semantic
specification of terms to be used in immunogenetics and immunoinformatics.
IMGT-ONTOLOGY comprises six main concepts: IDENTIFICATION, CLASSIFICATION,
DESCRIPTION, NUMEROTATION, ORIENTATION and OBTENTION. Based on these concepts,
the controlled vocabulary and the annotation rules necessary for the
immunogenetics data identification, classification, description and numbering
and for the management of IMGT knowledge are defined in the IMGT Scientific
chart. IMGT is the international reference in immunogenetics and
immunoinformatics for medical research (repertoire analysis of the IG antibody
sites and of the TR recognition sites in autoimmune and infectious diseases,
AIDS, leukemias, lymphomas, myelomas), veterinary research (IG and TR
repertoires in farm and wild life species), genome diversity and genome
evolution studies of the adaptive immune responses, biotechnology related to
antibody engineering (single chain Fragment variable (scFv), phage displays,
combinatorial libraries, chimeric, humanized and human antibodies), diagnostics
(detection and follow up of residual diseases) and therapeutical approaches
(grafts, immunotherapy, vaccinology). IMGT is freely available at
http://imgt.cines.fr.
DOI: 10.1186/1745-7580-1-3
PMCID: PMC1312312
PMID: 16305737
|
http://www.ncbi.nlm.nih.gov/pubmed/15034132
|
1. Mol Biol Evol. 2004 Jul;21(7):1278-82. doi: 10.1093/molbev/msh125. Epub 2004
Mar 19.
Reconciling the numbers: ESTs versus protein-coding genes.
Nekrutenko A(1).
Author information:
(1)Department of Biochemistry and Molecular Biology, The Huck Institutes for
Life Sciences, Pennsylvania State University, University Park, PA, USA.
nekrut@psu.edu
The number of expressed sequences greatly surpasses the estimated number of
protein-coding genes in mammalian genomes. An evolutionary approach reveals that
only 9% to 14% of human-expressed and mouse-expressed sequences are able to code
for proteins. Clustering of these sequences using cross-species relationships
suggests that millions of expressed sequences may correspond to only
approximately 20,000 distinct protein-coding transcripts.
DOI: 10.1093/molbev/msh125
PMID: 15034132 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/17660570
|
1. Genetics. 2007 Oct;177(2):749-60. doi: 10.1534/genetics.107.072702. Epub 2007
Jul 29.
Natural variation for alleles under epigenetic control by the maize
chromomethylase zmet2.
Makarevitch I(1), Stupar RM, Iniguez AL, Haun WJ, Barbazuk WB, Kaeppler SM,
Springer NM.
Author information:
(1)Department of Plant Biology, Microbial and Plant Genomics Institute,
University of Minnesota, Saint Paul, Minnesota 55108, USA.
The contribution of epigenetic alterations to natural variation for gene
transcription levels remains unclear. In this study, we investigated the
functional targets of the maize chromomethylase ZMET2 in multiple inbred lines
to determine whether epigenetic changes conditioned by this chromomethylase are
conserved or variable within the species. Gene expression microarrays were
hybridized with RNA samples from the inbred lines B73 and Mo17 and from
near-isogenic derivatives containing the loss-of-function allele zmet2-m1. A set
of 126 genes that displayed statistically significant differential expression in
zmet2 mutants relative to wild-type plants in at least one of the two genetic
backgrounds was identified. Analysis of the transcript levels in both wild-type
and mutant individuals revealed that only 10% of these genes were affected in
zmet2 mutants in both B73 and Mo17 genetic backgrounds. Over 80% of the genes
with expression patterns affected by zmet2 mutations display variation for gene
expression between wild-type B73 and Mo17 plants. Further analysis was performed
for 7 genes that were transcriptionally silent in wild-type B73, but expressed
in B73 zmet2-m1, wild-type Mo17, and Mo17 zmet2-m1 lines. Mapping experiments
confirmed that the expression differences in wild-type B73 relative to Mo17
inbreds for these genes were caused by cis-acting regulatory variation.
Methylation-sensitive PCR and bisulfite sequencing demonstrated that for 5 of
these genes the CpNpG methylation in the wild-type B73 genetic background was
substantially decreased in the B73 zmet2-m1 mutant and in wild-type Mo17. A
survey of eight maize inbreds reveals that each of these 5 genes exhibit
transcriptionally silent and methylated states in some inbred lines and
unmethylated, expressed states in other inbreds, providing evidence for natural
variation in epigenetic states for some maize genes.
DOI: 10.1534/genetics.107.072702
PMCID: PMC2034640
PMID: 17660570 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/18040051
|
1. Proc Natl Acad Sci U S A. 2007 Dec 4;104(49):19428-33. doi:
10.1073/pnas.0709013104. Epub 2007 Nov 26.
Distinguishing protein-coding and noncoding genes in the human genome.
Clamp M(1), Fry B, Kamal M, Xie X, Cuff J, Lin MF, Kellis M, Lindblad-Toh K,
Lander ES.
Author information:
(1)Broad Institute of Massachusetts Institute of Technology and Harvard, 7
Cambridge Center, Cambridge, MA 02142, USA. mclamp@broad.mit.edu
Although the Human Genome Project was completed 4 years ago, the catalog of
human protein-coding genes remains a matter of controversy. Current catalogs
list a total of approximately 24,500 putative protein-coding genes. It is
broadly suspected that a large fraction of these entries are functionally
meaningless ORFs present by chance in RNA transcripts, because they show no
evidence of evolutionary conservation with mouse or dog. However, there is
currently no scientific justification for excluding ORFs simply because they
fail to show evolutionary conservation: the alternative hypothesis is that most
of these ORFs are actually valid human genes that reflect gene innovation in the
primate lineage or gene loss in the other lineages. Here, we reject this
hypothesis by carefully analyzing the nonconserved ORFs-specifically, their
properties in other primates. We show that the vast majority of these ORFs are
random occurrences. The analysis yields, as a by-product, a major revision of
the current human catalogs, cutting the number of protein-coding genes to
approximately 20,500. Specifically, it suggests that nonconserved ORFs should be
added to the human gene catalog only if there is clear evidence of an encoded
protein. It also provides a principled methodology for evaluating future
proposed additions to the human gene catalog. Finally, the results indicate that
there has been relatively little true innovation in mammalian protein-coding
genes.
DOI: 10.1073/pnas.0709013104
PMCID: PMC2148306
PMID: 18040051 [Indexed for MEDLINE]
Conflict of interest statement: The authors declare no conflict of interest.
|
http://www.ncbi.nlm.nih.gov/pubmed/7375968
|
1. South Med J. 1980 May;73(5):555-63. doi: 10.1097/00007611-198005000-00005.
Acute febrile juvenile rheumatoid arthritis in adults: cause of polyarthritis
and fever.
Goldman JA, Beard MR, Casey HL.
Acute febrile juvenile rheumatoid arthritis (JRA) of adult onset is often
diagnosed by ruling out other problems. The classification of JRA is primarily
based on the distinct type of onset, of which there are usually three: (1) acute
febrile or Still's type, (2) polyarticular, and (3) monoarticular pauciarticular
arthritis. Fever of unknown cause is frequently the initial symptom. This type
of arthritis may be characterized by any or all of the following: unexplained
high fever, rash, weight loss, lymphadenopathy, splenomegaly, pericarditis,
pleurisy, pneumonitis, abdominal pain, myalgias, arthralgias, arthritis, sore
throat, leukocytosis, anemia, circulating immune complexes, liver test
abnormalities, and carpal-metacarpal and tarsal-metatarsal fusion. Patients
often respond dramatically to anti-inflammatory agents. Corticosteroids, gold
salts, penicillamine, and cytotoxic drugs have been effective for certain
patients. The prognosis of the disease has been generally favorable. Although
symptoms may recur, remission can be prolonged.
DOI: 10.1097/00007611-198005000-00005
PMID: 7375968 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/22108462
|
1. Ned Tijdschr Geneeskd. 2011;155(46):A4124.
[Antibiotics do more than cause resistance].
[Article in Dutch]
Bonten MJ(1).
Author information:
(1)Universitair Medisch Centrum, afd. Medische microbiologie, Utrecht, the
Netherlands. mbonten@umcutrecht.nl
Limiting antibiotic use is one of the most important measures to prevent and
control emergence of antibiotic resistance. Therefore, antibiotics should
usually only be prescribed for infection. Yet recent well-designed studies have
demonstrated that prophylactic antibiotic use is of significant benefit to
patients prone to developing infections. Study patients suffered from recurrent
urinary tract infections, COPD or were mechanically ventilated in intensive care
units. In the first 2 populations, use of antibiotics was associated with an
increase in carriage of antibiotic-resistant bacteria, but in intensive care
patients the opposite was documented. These studies demonstrate that antibiotics
do more than cause resistance. The pros and cons of prophylactic antibiotic use
must therefore be carefully considered.
PMID: 22108462 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/11498704
|
1. Rev Esp Quimioter. 2000 Dec;13(4):379-83.
[Prospective, comparative study (1994-1998) of the influence of short-term
prophylactic treatment with azithromycin on patients with advanced COPD].
[Article in Spanish]
Gómez J(1), Baños V, Simarro E, Lorenzo Cruz M, Ruiz Gómez J, Latour J, Garcia
Martin E, Canteras M, Valdes M.
Author information:
(1)Servicio de Medicina Interna-Infecciosas, Hospital Universitario Virgen
Arrixaca, Murcia.
Despite the advances in therapy, chronic obstructive pulmonary disease (COPD)
requires frequent hospital admissions due to acute exacerbations. We carried out
a prospective randomized study of two groups of patients with COPD, one (n = 54)
treated with azithromycin (500 mg/day) for three days every 21 days during the
winter months, and a control group (n = 40) without treatment. A statistically
significant reduction in the number of acute infectious episodes (187) and
hospital admissions (22) was observed in the treated group versus the control
group (249 and 45, respectively). A short prophylactic treatment course with
azithromycin is a good alternative in the management of patients with severe,
advanced COPD, and could lead to an improvement in social and healthcare costs
PMID: 11498704 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/10781108
|
1. Proc Natl Acad Sci U S A. 2000 Apr 25;97(9):4979-84. doi:
10.1073/pnas.97.9.4979.
Conserved plant genes with similarity to mammalian de novo DNA
methyltransferases.
Cao X(1), Springer NM, Muszynski MG, Phillips RL, Kaeppler S, Jacobsen SE.
Author information:
(1)Department of Molecular, Cell and Developmental Biology, University of
California, Los Angeles, CA 90095-1606, USA.
DNA methylation plays a critical role in controlling states of gene activity in
most eukaryotic organisms, and it is essential for proper growth and
development. Patterns of methylation are established by de novo
methyltransferases and maintained by maintenance methyltransferase activities.
The Dnmt3 family of de novo DNA methyltransferases has recently been
characterized in animals. Here we describe DNA methyltransferase genes from both
Arabidopsis and maize that show a high level of sequence similarity to Dnmt3,
suggesting that they encode plant de novo methyltransferases. Relative to all
known eukaryotic methyltransferases, these plant proteins contain a novel
arrangement of the motifs required for DNA methyltransferase catalytic activity.
The N termini of these methyltransferases contain a series of
ubiquitin-associated (UBA) domains. UBA domains are found in several ubiquitin
pathway proteins and in DNA repair enzymes such as Rad23, and they may be
involved in ubiquitin binding. The presence of UBA domains provides a possible
link between DNA methylation and ubiquitin/proteasome pathways.
DOI: 10.1073/pnas.97.9.4979
PMCID: PMC18343
PMID: 10781108 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/21060858
|
1. PLoS Genet. 2010 Oct 28;6(10):e1001182. doi: 10.1371/journal.pgen.1001182.
The de novo cytosine methyltransferase DRM2 requires intact UBA domains and a
catalytically mutated paralog DRM3 during RNA-directed DNA methylation in
Arabidopsis thaliana.
Henderson IR(1), Deleris A, Wong W, Zhong X, Chin HG, Horwitz GA, Kelly KA,
Pradhan S, Jacobsen SE.
Author information:
(1)Department of Molecular, Cell, and Developmental Biology, University of
California Los Angeles, Los Angeles, California, United States of America.
Eukaryotic DNA cytosine methylation can be used to transcriptionally silence
repetitive sequences, including transposons and retroviruses. This silencing is
stable between cell generations as cytosine methylation is maintained
epigenetically through DNA replication. The Arabidopsis thaliana Dnmt3 cytosine
methyltransferase ortholog DOMAINS rearranged methyltransferase2 (DRM2) is
required for establishment of small interfering RNA (siRNA) directed DNA
methylation. In mammals PIWI proteins and piRNA act in a convergently evolved
RNA-directed DNA methylation system that is required to repress transposon
expression in the germ line. De novo methylation may also be independent of RNA
interference and small RNAs, as in Neurospora crassa. Here we identify a clade
of catalytically mutated DRM2 paralogs in flowering plant genomes, which in
A.thaliana we term domains rearranged methyltransferase3 (DRM3). Despite being
catalytically mutated, DRM3 is required for normal maintenance of non-CG DNA
methylation, establishment of RNA-directed DNA methylation triggered by repeat
sequences and accumulation of repeat-associated small RNAs. Although the
mammalian catalytically inactive Dnmt3L paralogs act in an analogous manner,
phylogenetic analysis indicates that the DRM and Dnmt3 protein families diverged
independently in plants and animals. We also show by site-directed mutagenesis
that both the DRM2 N-terminal UBA domains and C-terminal methyltransferase
domain are required for normal RNA-directed DNA methylation, supporting an
essential targeting function for the UBA domains. These results suggest that
plant and mammalian RNA-directed DNA methylation systems consist of a
combination of ancestral and convergent features.
DOI: 10.1371/journal.pgen.1001182
PMCID: PMC2965745
PMID: 21060858 [Indexed for MEDLINE]
Conflict of interest statement: The authors have declared that no competing
interests exist.
|
http://www.ncbi.nlm.nih.gov/pubmed/9520923
|
1. J Gerontol A Biol Sci Med Sci. 1998 Mar;53(2):M155-62. doi:
10.1093/gerona/53a.2.m155.
The structure of depression among elderly institution residents: affective and
somatic correlates of physical frailty.
Parmelee PA(1), Lawton MP, Katz IR.
Author information:
(1)Department of Biostatistics and Epidemiology, University of Pennsylvania
School of Medicine, Philadelphia, USA. paparmelee@aol.com
BACKGROUND: Confounding of depression with somatic illness and anxiety, a
problem in any age group, may be especially troublesome in frail older persons.
This paper examined this problem in a factor analytic study of the structure of
depressive symptomatology, identifying affective and somatic symptom clusters
and relating those clusters to health and functional variables cross-sectionally
and prospectively over a 1-year interval.
METHODS: The factor structure of a DSM-IV symptom checklist was examined among
1,245 elderly long-term care residents. Regression analyses examined the
association of resulting factors with cognition, functional disability, self-
and physician-rated health, and pain at baseline and a year later. One-year
mortality was also examined.
RESULTS: Factor analysis revealed three unique symptom clusters: depressed mood,
somatic symptoms, and psychic anxiety. Depressed mood and somatic symptoms were
associated cross-sectionally with all functional health variables, but psychic
anxiety was associated only with pain. Longitudinally, depressed mood was the
only independent predictor of decline in cognition, functional ability,
physician-rated health, and mortality; the last effect, however, did not
withstand control for baseline health and functioning. Somatic symptoms at
baseline predicted decrement in self-rated health a year later. Effects varied
as a function of cognitive status.
CONCLUSIONS: These data suggest that concerns about the confounding role of
somatic symptoms in the association of depression with physical health are
unfounded. Although somatic symptoms of depression and anxiety were associated
with health and functional status cross-sectionally, depressed mood was by far
the stronger predictor of health declines over time.
DOI: 10.1093/gerona/53a.2.m155
PMID: 9520923 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/1988577
|
1. J Clin Oncol. 1991 Feb;9(2):305-12. doi: 10.1200/JCO.1991.9.2.305.
A prospective randomized trial comparing epirubicin monochemotherapy to two
fluorouracil, cyclophosphamide, and epirubicin regimens differing in epirubicin
dose in advanced breast cancer patients. The French Epirubicin Study Group.
[No authors listed]
Comment in
J Clin Oncol. 1991 Jul;9(7):1321-2. doi: 10.1200/JCO.1991.9.7.1321.
The French Epirubicin Study Group carried out a randomized trial comparing
epirubicin alone 75 mg/m2 with fluorouracil (5FU) 500 mg/m2, cyclophosphamide
500 mg/m2, and epirubicin 50 mg/m2 (FEC 50) and 5FU 500 mg/m2, cyclophosphamide
500 mg/m2, and epirubicin 75 mg/m2 (FEC 75) as first treatment for advanced
breast cancer patients. Patients were stratified according to whether or not
there were bone metastases only. Four hundred twelve patients entered this
trial; 378 were assessable for tolerability and 365 for efficacy. The overall
response rates were comparable between FEC 50 (44.6%) and FEC 75 (44.7%), but
both were better than the epirubicin alone (30.6%) (P = .04 and P = .0006,
respectively). The complete response rate was better in FEC 75 (15.5%) than in
FEC 50 (7%) (P = .025) or epirubicin (4%) (P = .002). Similar results were
obtained in the group of patients without bone-only metastases. No difference in
the three treatments was observed in the patients with bone metastases only.
Mean durations of response were similar in the three groups, being 412 days, 440
days, and 350 days for FEC 50, FEC 75, and epirubicin, respectively. Patients
without previous adjuvant chemotherapy fared better than those with previous
treatment (without anthracyclines). Tolerability was fair in the three groups.
Overall, the epirubicin-alone group showed better tolerance than the two other
groups, which did not differ significantly. Time to progression and survival
were not different among the three groups, but more early relapses occurred in
the epirubicin and FEC 50 groups; survival seemed to be better during the first
8 months in the FEC 75 group, and the survival difference between the epirubicin
group and the FEC 75 group was of borderline significance. No difference in
survival was observed between epirubicin- and FEC 50-group patients, even though
the response rate was significantly worse in the monochemotherapy group.
DOI: 10.1200/JCO.1991.9.2.305
PMID: 1988577 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/23021223
|
1. Cell. 2012 Sep 28;151(1):167-80. doi: 10.1016/j.cell.2012.07.034.
Dual binding of chromomethylase domains to H3K9me2-containing nucleosomes
directs DNA methylation in plants.
Du J(1), Zhong X, Bernatavichute YV, Stroud H, Feng S, Caro E, Vashisht AA,
Terragni J, Chin HG, Tu A, Hetzel J, Wohlschlegel JA, Pradhan S, Patel DJ,
Jacobsen SE.
Author information:
(1)Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York,
NY 10065, USA.
DNA methylation and histone modification exert epigenetic control over gene
expression. CHG methylation by CHROMOMETHYLASE3 (CMT3) depends on histone H3K9
dimethylation (H3K9me2), but the mechanism underlying this relationship is
poorly understood. Here, we report multiple lines of evidence that CMT3
interacts with H3K9me2-containing nucleosomes. CMT3 genome locations nearly
perfectly correlated with H3K9me2, and CMT3 stably associated with
H3K9me2-containing nucleosomes. Crystal structures of maize CMT3 homolog ZMET2,
in complex with H3K9me2 peptides, showed that ZMET2 binds H3K9me2 via both bromo
adjacent homology (BAH) and chromo domains. The structures reveal an aromatic
cage within both BAH and chromo domains as interaction interfaces that capture
H3K9me2. Mutations that abolish either interaction disrupt CMT3 binding to
nucleosomes and show a complete loss of CMT3 activity in vivo. Our study
establishes dual recognition of H3K9me2 marks by BAH and chromo domains and
reveals a distinct mechanism of interplay between DNA methylation and histone
modification.
Copyright © 2012 Elsevier Inc. All rights reserved.
DOI: 10.1016/j.cell.2012.07.034
PMCID: PMC3471781
PMID: 23021223 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/24314697
|
1. J Am Med Dir Assoc. 2014 Jan;15(1):76.e7-76.e12. doi:
10.1016/j.jamda.2013.10.001. Epub 2013 Dec 4.
Frailty predicts new and persistent depressive symptoms among community-dwelling
older adults: findings from Singapore longitudinal aging study.
Feng L(1), Nyunt MS(1), Feng L(1), Yap KB(2), Ng TP(3).
Author information:
(1)Gerontology Research Program, Department of Psychological Medicine, Yong Loo
Lin School of Medicine, National University of Singapore, Singapore.
(2)Geriatric Medicine Department, Alexandra Hospital, Ministry of Health,
Singapore.
(3)Gerontology Research Program, Department of Psychological Medicine, Yong Loo
Lin School of Medicine, National University of Singapore, Singapore. Electronic
address: pcmngtp@nus.edu.sg.
OBJECTIVE: This study aimed to examine the cross-sectional and longitudinal
relationships between physical frailty at baseline and depressive symptoms at
baseline and at follow-up.
DESIGN: Four-year prospective study.
SETTING: Communities in the South East Region of Singapore.
PARTICIPANTS: We analyzed data of 1827 older Chinese adults aged 55 and above in
the Singapore Longitudinal Aging Study-I.
MEASUREMENTS: The frailty phenotype (based on Fried criteria) was determined at
baseline, depressive symptoms (Geriatric Depression Scale ≥ 5) at baseline and
follow-ups at 2 and 4 years.
RESULTS: The mean age of the population was 65.9 (standard deviation 7.26). At
baseline, 11.4% (n = 209) had depressive symptoms, 32.4% (n = 591) were prefrail
and 2.5% (n = 46) were frail. In cross-sectional analysis of baseline data, the
adjusted odds ratios (OR)s and 95% confidence intervals controlling for
demographic, comorbidities, and other confounders were 1.69 (1.23-2.33) for
prefrailty and 2.36 (1.08-5.15) for frailty, (P for linear trend <.001). In
longitudinal data analyses, prospective associations among all participants
were: prefrail: OR = 1.86 (1.08-3.20); frail: OR = 3.09 (1.12-8.50); (P for
linear trend = .009). Among participants free of depressive symptoms at
baseline, similar prospective associations were found: prefrail OR = 2.26
(1.12-4.57); frail: OR = 3.75 (1.07-13.16); (P for linear trend = .009).
CONCLUSION: These data support a significant role of frailty as a predictor of
depression in a relatively younger old Chinese population. Further observational
and interventional studies should explore short-term dynamic and bidirectional
associations and the effects of frailty reversal on depression risk.
Copyright © 2014 American Medical Directors Association, Inc. Published by
Elsevier Inc. All rights reserved.
DOI: 10.1016/j.jamda.2013.10.001
PMID: 24314697 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/9584105
|
1. Genetics. 1998 May;149(1):307-18. doi: 10.1093/genetics/149.1.307.
A DNA methyltransferase homolog with a chromodomain exists in multiple
polymorphic forms in Arabidopsis.
Henikoff S(1), Comai L.
Author information:
(1)Howard Hughes Medical Institute, Fred Hutchinson Cancer Research Center,
Seattle, Washington 98109-1024, USA. steveh@muller.fhcrc.org
Chromodomains are thought to mediate protein-protein interactions between
chromatin components. We have detected a chromodomain embedded within the
catalytic region of a predicted Arabidopsis DNA methyltransferase that is
diverged from other eukaryotic enzymes. The 791 residue "chromomethylase" (CMT1)
is encoded by a floral transcript that is spliced from 20 exons and is present
at only approximately 1/10(-7) of total mRNA. Genomic sequencing reveals an
ancient haplotype split at CMT1 between Col-0 + Metz and the other ecotypes
examined. In the Col-0 + Metz haplotype, alternative mRNA processing at intron
13 truncates the coding region. In Ler, RLD, and No-0, similar truncation is
caused by insertion of an intact retrotransposon, Evelknievel, which is present
as a single copy in Ler and RLD and is currently methylated and inactive.
Evelknievel is found at this site on a single branch that connects the Ler, RLD,
and No-0 ecotypes but is absent from the genomes of all other ecotypes examined.
A stop codon within exon 6 of the Metz ecotype confirms that CMT1 is
nonessential. Nevertheless, comparison to CMT1 of Cardaminopsis arenosa, an
outcrossing relative, indicates conservation for DNA methyltransferase function.
We discuss how allelic diversity of CMT1 may reflect loosened selective
constraints in a self-fertilizing species such as Arabidopsis thaliana.
DOI: 10.1093/genetics/149.1.307
PMCID: PMC1460135
PMID: 9584105 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/21795448
|
1. J Clin Endocrinol Metab. 2011 Oct;96(10):2997-3006. doi: 10.1210/jc.2011-1193.
Epub 2011 Jul 27.
Clinical review: The effect of vitamin D on falls: a systematic review and
meta-analysis.
Murad MH(1), Elamin KB, Abu Elnour NO, Elamin MB, Alkatib AA, Fatourechi MM,
Almandoz JP, Mullan RJ, Lane MA, Liu H, Erwin PJ, Hensrud DD, Montori VM.
Author information:
(1)Knowledge and Encounter Research Unit, and Division of Preventive, Mayo
Clinic, Rochester, Minnesota 55905, USA. murad.mohammad@mayo.edu
Erratum in
J Clin Endocrinol Metab. 2021 Mar 8;106(3):e1495. doi:
10.1210/clinem/dgaa928.
CONTEXT: Vitamin D affects bone and muscle health and likely reduces the risk of
falls in the elderly.
OBJECTIVE: The aim of this systematic review is to summarize the existing
evidence on vitamin D use and the risk of falls.
DATA SOURCES: We searched electronic databases from inception through August
2010.
STUDY SELECTION: Eligible studies were randomized controlled trials in which the
intervention was vitamin D and the incidence of falls was reported.
DATA EXTRACTION: Reviewers working in duplicate and independently extracted
study characteristics, quality, and outcomes data.
DATA SYNTHESIS: Odds ratio and associated 95% confidence interval were estimated
from each study and pooled using the random effects model.
RESULTS: We found 26 eligible trials of moderate quality that enrolled 45,782
participants, the majority of which were elderly and female. Vitamin D use was
associated with statistically significant reduction in the risk of falls (odds
ratio for suffering at least one fall, 0.86; 95% confidence interval,
0.77-0.96). This effect was more prominent in patients who were vitamin D
deficient at baseline and in studies in which calcium was coadministered with
vitamin D. The quality of evidence was low to moderate because of heterogeneity
and publication bias.
CONCLUSIONS: Vitamin D combined with calcium reduces the risk of falls. The
reduction in studies without calcium coadministration did not reach statistical
significance. The majority of the evidence is derived from trials enrolling
elderly women.
DOI: 10.1210/jc.2011-1193
PMID: 21795448 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/23922354
|
1. J Clin Endocrinol Metab. 2013 Aug;98(8):E1283-304. doi: 10.1210/jc.2013-1195.
Optimal vitamin D status: a critical analysis on the basis of evidence-based
medicine.
Bouillon R(1), Van Schoor NM, Gielen E, Boonen S, Mathieu C, Vanderschueren D,
Lips P.
Author information:
(1)Clinical and Experimental Endocrinology, KU Leuven, Department of
Endocrinology, Herestraat 49 ON1, Box 902, 3000 Leuven, Belgium.
roger.bouillon@med.kuleuven.be
CONTEXT: Public health authorities around the world recommend widely variable
supplementation strategies for adults, whereas several professional
organizations, including The Endocrine Society, recommend higher
supplementation.
METHODS: We analyzed published randomized controlled clinical trials to define
the optimal intake or vitamin D status for bone and extraskeletal health.
CONCLUSIONS: The extraskeletal effects of vitamin D are plausible as based on
preclinical data and observational studies. However, apart from the beneficial
effects of 800 IU/d of vitamin D3 for reduction of falls in the elderly,
causality remains yet unproven in randomized controlled trials (RCTs). The
greatest risk for cancer, infections, cardiovascular and metabolic diseases is
associated with 25-hydroxyvitamin D (25OHD) levels below 20 ng/mL. There is
ample evidence from RCTs that calcium and bone homeostasis, estimated from serum
1,25-dihydroxyvitamin D and PTH, calcium absorption, or bone mass, can be
normalized by 25OHD levels above 20 ng/mL. Moreover, vitamin D supplementation
(800 IU/d) in combination with calcium can reduce fracture incidence by about
20%. Such a dose will bring serum levels of 25OHD above 20 ng/mL in nearly all
postmenopausal women. Based on calculations of the metabolic clearance of 25OHD,
a daily intake of 500-700 IU of vitamin D3 is sufficient to maintain serum 25OHD
levels of 20 ng/mL. Therefore, the recommendations for a daily intake of
1500-2000 IU/d or serum 25OHD levels of 30 ng or higher for all adults or
elderly subjects, as suggested by The Endocrine Society Task Force, are
premature. Fortunately, ongoing RCTs will help to guide us to solve this
important public health question.
DOI: 10.1210/jc.2013-1195
PMID: 23922354 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/24201379
|
1. Sci Rep. 2013 Nov 8;3:3171. doi: 10.1038/srep03171.
Identification of telomere-associated molecules by engineered DNA-binding
molecule-mediated chromatin immunoprecipitation (enChIP).
Fujita T(1), Asano Y, Ohtsuka J, Takada Y, Saito K, Ohki R, Fujii H.
Author information:
(1)Combined Program on Microbiology and Immunology, Research Institute for
Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, 565-0871 Osaka,
Japan.
Biochemical analysis of molecular interactions in specific genomic regions
requires their isolation while retaining molecular interactions in vivo. Here,
we report isolation of telomeres by engineered DNA-binding molecule-mediated
chromatin immunoprecipitation (enChIP) using a transcription activator-like
(TAL) protein recognizing telomere repeats. Telomeres recognized by the tagged
TAL protein were immunoprecipitated with an antibody against the tag and
subjected to identification of telomere-binding molecules. enChIP-mass
spectrometry (enChIP-MS) targeting telomeres identified known and novel
telomere-binding proteins. The data have been deposited to the ProteomeXchange
with identifier PXD000461. In addition, we showed that RNA associated with
telomeres could be isolated by enChIP. Identified telomere-binding molecules may
play important roles in telomere biology. enChIP using TAL proteins would be a
useful tool for biochemical analysis of specific genomic regions of interest.
DOI: 10.1038/srep03171
PMCID: PMC3821016
PMID: 24201379 [Indexed for MEDLINE]
Conflict of interest statement: T.F. and H.F. filed a patent application on
enChIP.
|
http://www.ncbi.nlm.nih.gov/pubmed/22879880
|
1. PLoS One. 2012;7(8):e40728. doi: 10.1371/journal.pone.0040728. Epub 2012 Aug
7.
Functional dissection of HOXD cluster genes in regulation of neuroblastoma cell
proliferation and differentiation.
Zha Y(1), Ding E, Yang L, Mao L, Wang X, McCarthy BA, Huang S, Ding HF.
Author information:
(1)Cancer Center and Department of Pathology, Medical College of Georgia,
Georgia Health Sciences University, Augusta, Georgia, United States of America.
Retinoic acid (RA) can induce growth arrest and neuronal differentiation of
neuroblastoma cells and has been used in clinic for treatment of neuroblastoma.
It has been reported that RA induces the expression of several HOXD genes in
human neuroblastoma cell lines, but their roles in RA action are largely
unknown. The HOXD cluster contains nine genes (HOXD1, HOXD3, HOXD4, and
HOXD8-13) that are positioned sequentially from 3' to 5', with HOXD1 at the 3'
end and HOXD13 the 5' end. Here we show that all HOXD genes are induced by RA in
the human neuroblastoma BE(2)-C cells, with the genes located at the 3' end
being activated generally earlier than those positioned more 5' within the
cluster. Individual induction of HOXD8, HOXD9, HOXD10 or HOXD12 is sufficient to
induce both growth arrest and neuronal differentiation, which is associated with
downregulation of cell cycle-promoting genes and upregulation of neuronal
differentiation genes. However, induction of other HOXD genes either has no
effect (HOXD1) or has partial effects (HOXD3, HOXD4, HOXD11 and HOXD13) on
BE(2)-C cell proliferation or differentiation. We further show that knockdown of
HOXD8 expression, but not that of HOXD9 expression, significantly inhibits the
differentiation-inducing activity of RA. HOXD8 directly activates the
transcription of HOXC9, a key effector of RA action in neuroblastoma cells.
These findings highlight the distinct functions of HOXD genes in RA induction of
neuroblastoma cell differentiation.
DOI: 10.1371/journal.pone.0040728
PMCID: PMC3413684
PMID: 22879880 [Indexed for MEDLINE]
Conflict of interest statement: Competing Interests: The authors have declared
that no competing interests exist.
|
http://www.ncbi.nlm.nih.gov/pubmed/22955987
|
1. Genome Res. 2012 Sep;22(9):1760-74. doi: 10.1101/gr.135350.111.
GENCODE: the reference human genome annotation for The ENCODE Project.
Harrow J(1), Frankish A, Gonzalez JM, Tapanari E, Diekhans M, Kokocinski F, Aken
BL, Barrell D, Zadissa A, Searle S, Barnes I, Bignell A, Boychenko V, Hunt T,
Kay M, Mukherjee G, Rajan J, Despacio-Reyes G, Saunders G, Steward C, Harte R,
Lin M, Howald C, Tanzer A, Derrien T, Chrast J, Walters N, Balasubramanian S,
Pei B, Tress M, Rodriguez JM, Ezkurdia I, van Baren J, Brent M, Haussler D,
Kellis M, Valencia A, Reymond A, Gerstein M, Guigó R, Hubbard TJ.
Author information:
(1)Wellcome Trust Sanger Institute, Wellcome Trust Campus, Hinxton, Cambridge
CB10 1SA, United Kingdom. jla1@sanger.ac.uk
The GENCODE Consortium aims to identify all gene features in the human genome
using a combination of computational analysis, manual annotation, and
experimental validation. Since the first public release of this annotation data
set, few new protein-coding loci have been added, yet the number of alternative
splicing transcripts annotated has steadily increased. The GENCODE 7 release
contains 20,687 protein-coding and 9640 long noncoding RNA loci and has 33,977
coding transcripts not represented in UCSC genes and RefSeq. It also has the
most comprehensive annotation of long noncoding RNA (lncRNA) loci publicly
available with the predominant transcript form consisting of two exons. We have
examined the completeness of the transcript annotation and found that 35% of
transcriptional start sites are supported by CAGE clusters and 62% of
protein-coding genes have annotated polyA sites. Over one-third of GENCODE
protein-coding genes are supported by peptide hits derived from mass
spectrometry spectra submitted to Peptide Atlas. New models derived from the
Illumina Body Map 2.0 RNA-seq data identify 3689 new loci not currently in
GENCODE, of which 3127 consist of two exon models indicating that they are
possibly unannotated long noncoding loci. GENCODE 7 is publicly available from
gencodegenes.org and via the Ensembl and UCSC Genome Browsers.
DOI: 10.1101/gr.135350.111
PMCID: PMC3431492
PMID: 22955987 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/20230348
|
1. Med J Aust. 2010 Mar 15;192(6):319-22. doi:
10.5694/j.1326-5377.2010.tb03530.x.
A cluster randomised controlled trial to prevent injury due to falls in a
residential aged care population.
Ward JA(1), Harden M, Gibson RE, Byles JE.
Author information:
(1)Hunter New England Health, Newcastle, New South Wales.
John.Ward@hnehealth.nsw.gov.au
Comment in
Evid Based Nurs. 2010 Oct;13(4):124-5. doi: 10.1136/ebn1080.
OBJECTIVE: To test the effectiveness of using a full-time project nurse to
assist residential aged care facilities in using evidence-based approaches to
falls injury prevention.
DESIGN, SETTING AND PARTICIPANTS: Cluster randomised controlled trial involving
5391 residents in 88 aged care facilities in the Hunter and Lower Mid North
Coast areas of New South Wales. Residents were followed for 545 days or until
death or discharge. Data were collected from July 2005 to June 2007.
INTERVENTION: Employment of a project nurse to encourage best-practice falls
injury prevention strategies during the 17-month intervention period.
MAIN OUTCOME MEASURES: Monthly data about falls, falls injury and falls injury
prevention programs; audit of hospitalisation for fractured neck of femur.
RESULTS: Despite significant increases in the provision of hip protectors and
use of vitamin D supplementation in both intervention and control facilities,
there was no difference in the number of falls or falls injuries between the
intervention and control groups, nor a reduction in falls overall. There was
also no difference between the 7-month pre-intervention period and the
intervention period in the number of falls or falls injuries. Factors related to
residents having an increased risk of falls with fractured neck of femur
included being ambulant, having dementia, increasing age, and having a high
falls risk assessment score.
CONCLUSION: It is difficult to change falls risk among high-risk populations,
including people with dementia. The use of important strategies such as hip
protectors and vitamin D and calcium supplementation increased during the study,
probably with contamination of control facilities. Longer follow-up may be
required to measure the impact on falls outcomes of the strategy of using a
facilitating nurse.
TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry
ACTRN12605000540617.
DOI: 10.5694/j.1326-5377.2010.tb03530.x
PMID: 20230348 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/3209676
|
1. J Craniofac Genet Dev Biol. 1988;8(1):21-33.
Alterations in craniofacial growth induced by isotretinoin (13-cis-retinoic
acid) in mouse whole embryo and primary mesenchymal cell culture.
Watanabe T(1), Goulding EH, Pratt RM.
Author information:
(1)Experimental Teratogenesis Section, National Institute of Environmental
Health Sciences, Research Triangle Park, NC 27709.
Recent evidence has demonstrated that 13-cis-retinoic acid (13-cis-RA, or
isotretinoin) is responsible for various craniofacial malformations in the
rodent and human embryo. Our studies have been directed toward understanding
this effect using mouse whole embryo and primary cell cultures. In whole embryo
culture, 13-cis-RA caused significant overall embryonic growth retardation,
especially in the primary and secondary palatal processes. In embryos explanted
on day 10 of gestation and exposed for 24 or 48 hr, the mesenchyme beneath the
epithelium of the nasal and maxillary processes contained pyknotic nuclei as
well as a dramatically reduced number of nuclei incorporating 3H-thymidine. The
secondary palatal processes and the roof of the oral-nasal cavity had fewer
mesenchymal cells than control embryos. The incorporation of 3H-thymidine into
TCA-insoluble macromolecules was 30% less in the retinoid-treated heads. In
primary cell cultures from day-12 mouse secondary palatal mesenchyme, subsequent
cell growth was decreased at concentrations of 13-cis-RA greater than 1 X 10(-5)
M. After a 40-hr treatment period, labeling indices in retinoid-treated cells
were significantly lower than control values (25% compared with 40%). Retinoic
acid also caused a significant, concentration-dependent decrease in 3H-thymidine
incorporation. The inhibitory effect of 13-cis-RA on proliferation of oral-nasal
mesenchymal cells appears to be related to the production of craniofacial
malformations.
PMID: 3209676 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/10364522
|
1. Am J Hum Genet. 1999 Jul;65(1):104-10. doi: 10.1086/302467.
Monodactylous limbs and abnormal genitalia are associated with hemizygosity for
the human 2q31 region that includes the HOXD cluster.
Del Campo M(1), Jones MC, Veraksa AN, Curry CJ, Jones KL, Mascarello JT,
Ali-Kahn-Catts Z, Drumheller T, McGinnis W.
Author information:
(1)Division of Dysmorphology, Department of Pediatrics, University of
California, San Diego, La Jolla, CA, USA.
Vertebrates have four clusters of Hox genes (HoxA, HoxB, HoxC, and HoxD). A
variety of expression and mutation studies indicate that posterior members of
the HoxA and HoxD clusters play an important role in vertebrate limb
development. In humans, mutations in HOXD13 have been associated with type II
syndactyly or synpolydactyly, and, in HOXA13, with hand-foot-genital syndrome.
We have investigated two unrelated children with a previously unreported pattern
of severe developmental defects on the anterior-posterior (a-p) limb axis and in
the genitalia, consisting of a single bone in the zeugopod, either monodactyly
or oligodactyly in the autopod of all four limbs, and penoscrotal hypoplasia.
Both children are heterozygous for a deletion that eliminates at least eight
(HOXD3-HOXD13) of the nine genes in the HOXD cluster. We propose that the
patients' phenotypes are due in part to haploinsufficiency for HOXD-cluster
genes. This hypothesis is supported by the expression patterns of these genes in
early vertebrate embryos. However, the involvement of additional genes in the
region could explain the discordance, in severity, between these human
phenotypes and the milder, non-polarized phenotypes present in mice hemizygous
for HoxD cluster genes. These cases represent the first reported examples of
deficiencies for an entire Hox cluster in vertebrates and suggest that the
diploid dose of human HOXD genes is crucial for normal growth and patterning of
the limbs along the anterior-posterior axis.
DOI: 10.1086/302467
PMCID: PMC1378080
PMID: 10364522 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/18389144
|
1. Photochem Photobiol Sci. 2008 Mar;7(3):283-9. doi: 10.1039/b712847a. Epub 2007
Dec 7.
ALA and its clinical impact, from bench to bedside.
Krammer B(1), Plaetzer K.
Author information:
(1)University of Salzburg, Department of Molecular Biology, Austria.
barbara.krammer@sbg.ac.at
ALA-induced protoporphyrin IX (PpIX) is used for fluorescence diagnosis (ALA-FD)
and for fluorescence-guided resection of both (pre)malignant and non-malignant
diseases. ALA is also applied in photodynamic therapy (ALA-PDT) of superficial
(pre)malignant lesions in dermatology, urology, neurosurgery,
otorhinolaryngology, gynecology and gastroenterology. Today, ALA is approved as
Levulan for actinic keratoses, the ALA-methyl ester Metvix for actinic keratoses
and basal cell carcinoma, the ALA-hexyl ester Hexvix for the diagnosis of
bladder cancer and Gliolan for malignant glioma. The use of ALA for PDT and FD
was established around 25 years ago, with most of the fundamental knowledge
gained at the "bench" and implemented at the "bedside" due to the diligence of a
few researchers within the first 10 years of research. After 1993 ALA research
was taken up by many groups. For patient treatment, several factors are
relevant. Administered mainly in a topical or oral form, ALA penetrates tissue
in a sub-optimal way, which is currently improved by special techniques and the
use of ALA-esters. PpIX accumulation is elevated in many malignant tissues,
several tissue abnormalities, and in mucosa. It is also found at elevated levels
in macrophages, dendritic cells and activated lymphocytes. Following sufficient
PpIX accumulation in the target cells, irradiation is carried out which may be
accompanied by a burning sensation at the treatment site. Due to a saturation
process of PpIX formation and rapid photobleaching during irradiation the risk
of overtreatment is relatively low. Pharmacokinetical studies have demonstrated
a low systemic photosensitivity and excretion of PpIX via natural routes.
DOI: 10.1039/b712847a
PMID: 18389144 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/23870657
|
1. Neurologia. 2014 Apr;29(3):131-8. doi: 10.1016/j.nrl.2013.05.004. Epub 2013
Jul 17.
Observational, retrospective study of the effectiveness of 5-aminolevulinic acid
in malignant glioma surgery in Spain (The VISIONA study).
[Article in English, Spanish]
Díez Valle R(1), Slof J(2), Galván J(3), Arza C(3), Romariz C(3), Vidal C(4);
VISIONA study researchers.
Collaborators: Valle RD, i Rodriguez PT, Martínez GV, Cabezudo JM, García LM,
Sánchez JJ, Rodríguez EF, Ángel M, Sánchez A, Granados GO, Delgado ÁT, Bertrán
GC, Martín JJ, Ahicart GP, Díaz AP, Asunción CB, Acin RP, de Pedro Mdel Á,
Urzaiz LL, Barcia JA, Brin JR, Campa-Santamarina JM, Sánchez ÁM, Peña JM.
Author information:
(1)Departamento de Neurocirugía, Clínica Universidad de Navarra, Pamplona,
España. Electronic address: rdiezvalle@unav.es.
(2)Universidad Autónoma de Barcelona, Bellaterra, España.
(3)Laboratorios Gebro Pharma S.A., Barcelona, España.
(4)Needs and Aims, Barcelona, España.
OBJECTIVE: To assess effectiveness of 5-aminolevulinic acid (5-ALA, Gliolan(®))
in patients treated for malignant glioma under typical daily practice conditions
in Spain, using complete resection rate (CR) and progression free survival at 6
months (PFS6).
MATERIAL AND METHODS: Retrospective review of data from 18 neurosurgery
departments that were categorised as either using or not using 5-ALA. The study
included adult patients with suspected malignant gliomas for whom the intended
treatment plan included complete resection followed by radiotherapy and
chemotherapy with temozolomide. Postoperative MRI and clinical data representing
at least 6 months were required for inclusion. Rates of CR and PFS6 were
compared between patients with 5-ALA treatment and those without.
RESULTS: The study included 251 evaluable cases. CR and PFS6 rates were
significantly higher in the group of patients treated surgically with 5-ALA: CR,
67% versus 45%, p=.000; PFS6 for patients with grade IV tumours, 69% versus 48%;
p=.002. The differences retained their significance and magnitude after
adjusting for all covariates including age, functional status, and whether
gliomas were located in eloquent areas.
CONCLUSIONS: In this retrospective series, use of 5-ALA during habitual surgical
procedures in Spain was associated with a higher complete resection rate for
malignant glioma and increased PFS6 for grade iv glioma.
Copyright © 2013 Sociedad Española de Neurología. Published by Elsevier Espana.
All rights reserved.
DOI: 10.1016/j.nrl.2013.05.004
PMID: 23870657 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/20175080
|
1. Proteomics. 2010 Mar;10(6):1141-9. doi: 10.1002/pmic.200900258.
Prediction of the human membrane proteome.
Fagerberg L(1), Jonasson K, von Heijne G, Uhlén M, Berglund L.
Author information:
(1)School of Biotechnology, AlbaNova University Center, Royal Institute of
Technology (KTH), Stockholm, Sweden.
Membrane proteins are key molecules in the cell, and are important targets for
pharmaceutical drugs. Few three-dimensional structures of membrane proteins have
been obtained, which makes computational prediction of membrane proteins crucial
for studies of these key molecules. Here, seven membrane protein topology
prediction methods based on different underlying algorithms, such as hidden
Markov models, neural networks and support vector machines, have been used for
analysis of the protein sequences from the 21,416 annotated genes in the human
genome. The number of genes coding for a protein with predicted alpha-helical
transmembrane region(s) ranged from 5508 to 7651, depending on the method used.
Based on a majority decision method, we estimate 5539 human genes to code for
membrane proteins, corresponding to approximately 26% of the human
protein-coding genes. The largest fraction of these proteins has only one
predicted transmembrane region, but there are also many proteins with seven
predicted transmembrane regions, including the G-protein coupled receptors. A
visualization tool displaying the topologies suggested by the eight prediction
methods, for all predicted membrane proteins, is available on the public Human
Protein Atlas portal (www.proteinatlas.org).
DOI: 10.1002/pmic.200900258
PMID: 20175080 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/24856900
|
1. Immunity. 2014 Jun 19;40(6):865-79. doi: 10.1016/j.immuni.2014.03.014. Epub
2014 May 22.
miR-155 activates cytokine gene expression in Th17 cells by regulating the
DNA-binding protein Jarid2 to relieve polycomb-mediated repression.
Escobar TM(1), Kanellopoulou C(1), Kugler DG(2), Kilaru G(1), Nguyen CK(1),
Nagarajan V(3), Bhairavabhotla RK(1), Northrup D(4), Zahr R(1), Burr P(1), Liu
X(1), Zhao K(4), Sher A(2), Jankovic D(2), Zhu J(1), Muljo SA(5).
Author information:
(1)Laboratory of Immunology, National Institute of Allergy and Infectious
Diseases, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD
20892, USA.
(2)Laboratory of Parasitic Diseases, National Institute of Allergy and
Infectious Diseases, National Institutes of Health, 9000 Rockville Pike,
Bethesda, MD 20892, USA.
(3)Bioinformatics and Computational Biosciences Branch, National Institute of
Allergy and Infectious Diseases, National Institutes of Health, 9000 Rockville
Pike, Bethesda, MD 20892, USA.
(4)Systems Biology Center, National Heart, Lung and Blood Institute, National
Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA.
(5)Laboratory of Immunology, National Institute of Allergy and Infectious
Diseases, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD
20892, USA. Electronic address: stefan.muljo@nih.gov.
Comment in
Immunity. 2014 Jun 19;40(6):855-6. doi: 10.1016/j.immuni.2014.06.004.
Specification of the T helper 17 (Th17) cell lineage requires a well-defined set
of transcription factors, but how these integrate with posttranscriptional and
epigenetic programs to regulate gene expression is poorly understood. Here we
found defective Th17 cell cytokine expression in miR-155-deficient CD4+ T cells
in vitro and in vivo. Mir155 was bound by Th17 cell transcription factors and
was highly expressed during Th17 cell differentiation. miR-155-deficient Th17
and T regulatory (Treg) cells expressed increased amounts of Jarid2, a
DNA-binding protein that recruits the Polycomb Repressive Complex 2 (PRC2) to
chromatin. PRC2 binding to chromatin and H3K27 histone methylation was increased
in miR-155-deficient cells, coinciding with failure to express Il22, Il10, Il9,
and Atf3. Defects in Th17 cell cytokine expression and Treg cell homeostasis in
the absence of Mir155 could be partially suppressed by Jarid2 deletion. Thus,
miR-155 contributes to Th17 cell function by suppressing the inhibitory effects
of Jarid2.
Copyright © 2014 Elsevier Inc. All rights reserved.
DOI: 10.1016/j.immuni.2014.03.014
PMCID: PMC4092165
PMID: 24856900 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/9439011
|
1. Acta Chir Plast. 1997;39(3):91-6.
Different embryotoxic effect of vitamin A and B-carotene detected in the chick
embryo.
Peterka M(1), Peterková R, Likovský Z.
Author information:
(1)Department of Teratology, Academy of Sciences of the Czech Republic, Prague.
Erratum in
Acta Chir Plast 1997;39(4):112.
Teratogenicity of vitamin A was firstly detected in experimental animals in
1953. Nearly 30 years later, teratogenicity of vitamin A analogue-isotretinoin
was reported in humans. Isotretinoin induces serious birth defects of
craniofacial and central nervous system, cardiovascular system and thymic
malformations--in about 25% of babies exposed during the first trimester of
their prenatal development. The biological interconversion of isotretinoin to
vitamin A is known. That is why later epidemiological studies focused on high
vitamin A intake in pregnant woman: Women who use daily vitamin A supplements
during early pregnancy have approximately a two-fold increased risk of giving
birth to a malformed baby. On the basis of these data, replacement of vitamin A
has been recommended with its natural precursor B-carotene which is supposed to
be more safe for pregnant woman due to its limited absorption from intestine.
Aim of the present paper was to test a possible direct embryotoxic effect (i.e.
lethality + teratogenicity) of B-carotene in chick embryos and to compare these
results with known embryotoxicity of vitamin A in the same experimental model.
Single subgerminal or intaamniotic injection of vitamin A or B-carotene within
day 2-5 of incubation was used for estimation of the beginning of the
embryotoxicity range determining the minimal embryotoxic doses. Vitamin A
started to affect development between doses 0.3-0.3 microm [corrected] per
embryo. Malformations of head, extremities and heart were detected similarly
like in laboratory mammals and in man. B-carotene exhibited such an effect
neither after injection of the highest tested doses-100 microm [corrected] per
embryo. The results documented the strong difference in embryotoxicity between
vitamin A and B-carotene. After theoretical extrapolation of the results
achieved in the chick embryo, the minimal embryotoxic doses of vitamin A in
mammals were estimated to be between 0.1-1 mg/kg of maternal weight and those of
B-carotene to be more than 1000 mg/kg of maternal weight. Human epidemiological
studies have proved teratogenicity of vitamin A after daily doses 25,000
i.u.-8.3 mg (0.13 mg/kg)- and reduction of its maximum intake has been
recommended to 10,000 i.u. per day (0.05 mg/kg). The results about
teratogenicity of vitamin A achieved in the chick embryo are in agreement with
such a recommendation. Intake of vitamin A in the food is sufficient for
pregnant woman in common Czech population. Therefore, an artificial
supplementation of vitamin A brings risk of overdosage. If supplementation by
vitamin A is unavoidable during pregnancy, B-carotene should be preferred.
PMID: 9439011 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/7962395
|
1. Hum Reprod. 1994 Jun;9(6):1166-9. doi: 10.1093/oxfordjournals.humrep.a138652.
Gestational-age-dependent effects of retinoids on HCG secretion by placental
explants.
Barnea ER(1), Diamant M, Maruo T, Shurtz-Swirski R.
Author information:
(1)University of Medicine and Dentistry of New Jersey, Robert Wood Johnson
Medical School at Camden.
Vitamin A (VITA) is considered to be an essential nutrient in both pregnant and
non-pregnant states. It has been suggested that VITA, among others, is involved
in the process of morphogenesis. In contrast, synthetic derivatives of VITA,
specifically Tigasone (etretinate, TIG) and Roaccutane (isotretinoin, ROA), are
regarded as major teratogens. Therefore, in the present study we have examined
the effect of VITA and other retinoids on human chorionic gonadotrophin (HCG)
secretion by placental explants in the first trimester. Results show that, at
7-9 gestational weeks, all three compounds had a significant inhibitory effect
on HCG secretion. In the case of VITA, this inhibition was time-dependent. A
biphasic maximal inhibition was present at 1 microM concentrations when the
retinoids VITA, TIG and ROA were added for 16 h (52, 58 and 57%, respectively; P
< 0.01 by one-way analysis of variance). In contrast, the addition of the three
retinoids at 1 microM concentrations for 16 h had no significant effect on HCG
secretion by placental explants of 11-13 weeks gestational age. In conclusion,
both natural and synthetic retinoids demonstrate a significant inhibitory effect
on HCG secretion by the early placenta (pre-HCG peak). VITA may be involved in
causing a plateau and the later decline in HCG secretion. Inhibition of HCG
secretion by retinoids may contribute either directly or indirectly to their
teratogenicity.
DOI: 10.1093/oxfordjournals.humrep.a138652
PMID: 7962395 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/18684366
|
1. Rev Esp Cardiol. 2008 Aug;61(8):835-42.
Prognostic implication of frailty and depressive symptoms in an outpatient
population with heart failure.
[Article in English, Spanish]
Lupón J(1), González B, Santaeugenia S, Altimir S, Urrutia A, Más D, Díez C,
Pascual T, Cano L, Valle V.
Author information:
(1)Unitat d'Insuficiència Cardíaca, Hospital Universitari Germans Trias i Pujol,
Badalona, Barcelona, Spain. jlupon.germanstrias@gencat.cat
INTRODUCTION AND OBJECTIVES: Heart failure patients have high levels of frailty
and dependence. Our aim was to determine the impact of frailty and depressive
symptoms on the 1-year mortality rate and the rate of hospitalization for heart
failure during a follow-up period of 1 year.
METHODS: All patients underwent geriatric evaluation, and frailty and depressive
symptoms were identified. The study included 622 patients (72.5% male; median
age, 68 years; 92% in New York Heart Association class II or III; and median
ejection fraction, 30%).
RESULTS: During follow-up, 60 patients (9.5%) died and 101 (16.2%) were
hospitalized for heart failure. Overall, 39.9% of patients exhibited frailty,
while 25.2% had depressive symptoms. There were significant associations between
mortality at 1 year and the presence of frailty (16.9% vs. 4.8%; P< .001) and
depressive symptoms (15.3% vs. 7.7%; P=.006). There was also a significant
relationship between heart failure hospitalization and the presence of frailty
(20.5% vs. 13.3%; P=.01). No relationship was found between heart failure
hospitalization and depressive symptoms. Frailty was an independent predictor of
mortality but not of hospitalization.
CONCLUSIONS: Univariate analysis demonstrated significant relationships between
frailty and depressive symptoms and mortality at 1 year. In addition, there was
a significant relationship between frailty and the need for heart failure
hospitalization. However, only frailty showed prognostic value to predict
mortality, which was independent of other variables strongly associated to
outcome.
PMID: 18684366 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/20436882
|
1. Dermatoendocrinol. 2009 May;1(3):141-56. doi: 10.4161/derm.1.3.8474.
Role of FGFR2-signaling in the pathogenesis of acne.
Melnik BC(1).
Author information:
(1)Department of Dermatology; Environmental Medicine and Health Theory;
University of Osnabrück; Germany.
It is the purpose of this review to extend our understanding of the fibroblast
growth factor (FGF) receptor-2b-signaling network in the pathogenesis of acne. A
new concept of the role of FGFR2b-signaling in dermal-epithelial interaction for
skin appendage formation, pilosebaceous follicle homeostasis, comedogenesis,
sebaceous gland proliferation and lipogenesis is presented. The
FGFR2-gain-of-function mutations in Apert syndrome and unilateral acneiform
nevus are most helpful model diseases pointing the way to androgen-dependent
dermalepithelial FGFR2-signaling in acne. Androgen-mediated upregulation of
FGFR2b-signaling in acne-prone skin appears to be involved in the pathogenesis
of acne vulgaris. In organotypic skin cultures, keratinocyte-derived
interleukin-1alpha stimulated fibroblasts to secrete FGF7 which stimulated
FGFR2b-mediated keratinocyte proliferation. Postnatal deletion of FGFR2b in mice
resulted in severe sebaceous gland atrophy. The importance of FGFR2b in
sebaceous gland physiology is further supported by the mode of action of
anti-acne agents which have been proposed to attenuate FGFR2b-signaling.
Downregulation of FGFR2b-signaling by isotretinoin explains its therapeutic
effect in acne. Downregulation of FGFR2b-signaling during the first trimester of
pregnancy disturbs branched morphogenesis and explains retinoid embryotoxicity.
Insulin-like growth factor-1 (IGF-1), the mediator of growth hormone during
puberty, intracts with androgen-dependent FGFR2b-signaling and links androgen-
and FGF-mediated signal transduction important in sebaceous gland homeostasis.
The search for a follicular defect in the dermalepithelial regulation of growth
factor-signaling in acne-prone skin appears to be a most promising approach to
clarify the pathogenesis of acne.
DOI: 10.4161/derm.1.3.8474
PMCID: PMC2835907
PMID: 20436882
|
http://www.ncbi.nlm.nih.gov/pubmed/15545101
|
1. J Cosmet Laser Ther. 2004 Nov;6(3):156-62. doi: 10.1080/14764170410023785.
420 nm intense continuous light therapy for acne.
Omi T(1), Bjerring P, Sato S, Kawana S, Hankins RW, Honda M.
Author information:
(1)Department of Dermatology, Queen's Square Medical Center, Yokohama, Japan.
tom@olive.ocn.ne.jp
BACKGROUND: Topical antibiotics, isotretinoin or systemic antibiotics are
usually used for acne therapy. However, isotretinoin cannot be used during
pregnancy because it can cause significant birth defects while systemic
antibiotics can have adverse side effects such as gastrointestinal irritation,
photosensitivity and tetracycline sensitivity. Describe here is a
high-intensity, narrow-band, blue light (ClearLight) system, and its therapeutic
clinical effect is investigated on acne using cutaneous measurements, bacterial
observations and ultrastructural changes.
MATERIALS AND METHODS: A total of 28 adult healthy volunteers with facial acne
(mean age 28.1 years, range 16-56 years) were recruited for this study. They
were treated with a total of eight serial biweekly 15-minute treatment sessions.
Clinical counts of acne, as well as moisture, sebum and pH measurements were
taken between each session. Nine of the 28 patients were followed for 2-3 months
after the last treatment. Detection of bacteria in acne pustules was analyzed by
culture and by polymerase chain reaction (PCR). Ultrastructural changes were
examined in eight patients after four sessions of the light therapy.
RESULTS: All patients completed the study. Overall, there was a 64.7%
improvement in acne lesions. There were no bacterial changes before or after the
therapy, although damaged Propionibacterium acnes were observed at the
ultrastructural level.
CONCLUSIONS: ClearLight performed eight times over 4 weeks can be useful in the
treatment of acne. Further investigation will be needed to elucidate the
mechanism of action of ClearLight.
DOI: 10.1080/14764170410023785
PMID: 15545101 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/11445913
|
1. Braz Dent J. 2001;12(2):115-9.
Effect of isotretinoin on tooth germ and palate development in mouse embryos.
Balducci-Roslindo E(1), Silvério KG, Jorge MA, Gonzaga HF.
Author information:
(1)Discipline of Histology, Faculty of Dentistry of Araraquara, UNESP,
Araraquara, SP, Brazil. eleny@black.foar.unesp.br
Vitamin A and its derivatives, retinoic acid, tretinoin and isotretinoin, are
currently used in dermatological treatments. The administration of high doses of
this vitamin provokes congenital malformations in mice: cleft palate, maxillary
and mandibular hypoplasia and total or partial fusion of the maxillary incisors.
This study compares the tooth germs of the first maxillary and mandibular molars
of fetal mice submitted to isotretinoin during organogenesis. Twelve 60-day-old
female Mus musculus were divided into two groups on the 7th day of pregnancy:
treated group--1 mg isotretinoin per kg body weight, dissolved in vegetable oil,
was administered from the 7th to the 13th day of pregnancy; control
group--vegetable oil in equivalent volume was administered orally for the same
period. On the 16th day of pregnancy, the females were sacrificed, the fetuses
were removed and their heads amputated. After standard laboratory procedures,
6-micron thick serial slices were stained with hematoxylin and eosin for optical
microscopy examination. The results showed that both groups had closed palates
with no reminiscence of epithelial cells; however, the first molar germs of the
isotretinoin-treated animals showed delayed development compared to the control
animals.
PMID: 11445913 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/9035347
|
1. Teratology. 1996 Nov;54(5):255-65. doi:
10.1002/(SICI)1096-9926(199611)54:5<255::AID-TERA6>3.0.CO;2-Z.
Retinoid metabolism and transplacental pharmacokinetics in the cynomolgus monkey
following a nonteratogenic dosing regimen with all-trans-retinoic acid.
Tzimas G(1), Nau H, Hendrickx AG, Peterson PE, Hummler H.
Author information:
(1)Institut für Toxikologie und Embryopharmakologie, Freie Universität Berlin,
Germany.
Retinoids often exhibit a complex metabolic pattern and differential
transplacental kinetics, which make it difficult to pinpoint the proximate
compound responsible for the observed teratogenic effect. We have therefore
studied the pharmacokinetics and metabolism of all-trans-retinoic acid
(all-trans-RA) in cynomolgus monkeys following application of a nonteratogenic
dosing regimen and compared the results with corresponding data from a previous
study with a teratogenic dosing regimen with 13-cis-RA [Hummler et al. (1994)
Teratology 50:184-193]. All-trans-RA was administered to pregnant cynomolgus
monkeys (Macaca fascicularis) by nasogastric intubation at a dose of 5 mg/kg
body wt once daily from gestational day (GD) 16 to 26 and twice daily at 8-h
intervals from GD 27 to 31. Examination of the fetuses of four dams on GD 100
+/- 2 showed no embryotoxic or teratogenic effects of the applied dosing regimen
(Experiment 1). Maternal plasma retinoid pharmacokinetics on GD 16, 26, and 31
as well as embryonic retinoid profiles after the last drug administration on GD
31 were determined in thirteen further dams (Experiment 2). All-trans-RA reached
much lower plasma concentrations after the last two treatments on GD 31 than
after the first one on GD 16 and the eleventh one on GD 26 (0-24-h
area-under-the-concentration-time-curve (AUC) values: 104 +/- 59 ng x h/ml
(after the last treatment on GD 31), 189 +/- 110 (GD 16) and 393 +/- 305 ng x
h/ml (GD 26). The predominant plasma metabolites of all-trans-RA were its
beta-glucuronide and the beta-glucuronide of all-trans-4-oxo-RA. Both of these
retinoids accumulated in the plasma during the period of treatment and displayed
AUC values 5- to 30-fold higher than those of all-trans-RA. Embryonic
concentrations of all-trans-RA were not increased over endogenous levels after
the last administration on GD 31 when plasma concentrations were low. To
evaluate the placental transport of all-trans-RA in the presence of high plasma
concentrations, a further experiment was performed, in which a single dose of
all-trans-RA (10 mg/kg body wt) was given to four pregnant monkeys on GD 31, and
plasma pharmacokinetics as well as embryonic concentrations of retinoids at 4 h
post-treatment were determined (Experiment 3). This dosing schedule yielded high
plasma concentrations of all-trans-RA, while embryonic concentrations were about
40% of plasma levels. Based on the plasma AUC values on GDs 16 and 26 obtained
in Experiment 2 and the degree of placental transfer, as determined on GD 31 in
the presence of high plasma levels in Experiment 3, we estimated embryonic AUC
values for the 24-h period following the nonteratogenic doses on GDs 16 and 26
in Experiment 2. These AUC values were similarly high to the embryonic AUC value
of all-trans-RA obtained after application of the teratogenic dosing regimen
with 13-cis-RA [Hummler et al. (1994) Teratology 50:184-193]. In addition,
plasma AUC values of all-trans-RA were 2- to 7-fold higher after all-trans-RA
administration (present study) than after dosing with the teratogenic dose of
13-cis-RA. These results strengthen our recent suggestion that the teratogenic
effects induced in cynomolgus monkeys by 13-cis-RA treatment cannot solely
result from the action of all-trans-RA, but may involve 13-cis-RA and
13-cis-4-oxo-RA, which could act directly or function as transport vehicle.
DOI: 10.1002/(SICI)1096-9926(199611)54:5<255::AID-TERA6>3.0.CO;2-Z
PMID: 9035347 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/9091512
|
1. J Am Acad Dermatol. 1997 Mar;36(3 Pt 2):S86-90. doi:
10.1016/s0190-9622(97)70064-1.
A risk assessment of topical tretinoin as a potential human developmental toxin
based on animal and comparative human data.
Johnson EM(1).
Author information:
(1)Department of Pathology, Anatomy, and Cell Biology, Jefferson Medical College
of Thomas Jefferson University, Philadelphia, PA 19107, USA.
BACKGROUND: Although topically applied all-trans-retinoic acid (tretinoin)
undergoes minimal absorption and adds negligibly to normal endogenous levels,
its safety in humans is occasionally questioned because oral ingestion of
retinoids at therapeutic levels is known to entail teratogenic risks.
OBJECTIVE: To assess the actual potential for developmental toxicity from
treatment with topical tretinoin.
METHODS: Risk assessments were conducted on four known human developmental
toxicants (valproic acid, methotrexate, thalidomide, and isotretinoin) and a
potential developmental toxicant (acetylsalicylic acid). The margin of safety
for each chemical was calculated from the ratio of animal no-observed adverse
effect levels to human lowest-observed adverse effect levels or estimated
exposure doses.
RESULTS: The derived safety margin of more than 100 for topical tretinoin (with
2% absorption) contrasted sharply with the near unity values for valproic acid,
methotrexate, thalidomide, and isotretinoin and was larger than that for
acetylsalicylic acid.
CONCLUSION: These data support other epidemiologic and animal data that topical
tretinoin is not a potential human developmental toxicant.
DOI: 10.1016/s0190-9622(97)70064-1
PMID: 9091512 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/3162101
|
1. N Engl J Med. 1985 Oct 3;313(14):837-41. doi: 10.1056/NEJM198510033131401.
Retinoic acid embryopathy.
Lammer EJ, Chen DT, Hoar RM, Agnish ND, Benke PJ, Braun JT, Curry CJ, Fernhoff
PM, Grix AW Jr, Lott IT, et al.
Retinoic acid, an analogue of vitamin A, is known to be teratogenic in
laboratory animals and has recently been implicated in a few clinical case
reports. To study the human teratogenicity of this agent, we investigated 154
human pregnancies with fetal exposure to isotretinoin, a retinoid prescribed for
severe recalcitrant cystic acne. The outcomes were 95 elective abortions, 26
infants without major malformations, 12 spontaneous abortions, and 21 malformed
infants. A subset of 36 of the 154 pregnancies was observed prospectively. The
outcomes in this cohort were 8 spontaneous abortions, 23 normal infants, and 5
malformed infants. Exposure to isotretinoin was associated with an unusually
high relative risk for a group of selected major malformations (relative risk =
25.6; 95 per cent confidence interval, 11.4 to 57.5). Among the 21 malformed
infants we found a characteristic pattern of malformation involving
craniofacial, cardiac, thymic, and central nervous system structures. The
malformations included microtia/anotia (15 infants), micrognathia (6), cleft
palate (3), conotruncal heart defects and aortic-arch abnormalities (8), thymic
defects (7), retinal or optic-nerve abnormalities (4), and central nervous
system malformations (18). The pattern of malformation closely resembled that
produced in animal studies of retinoid teratogenesis. It is possible that a
major mechanism of isotretinoin teratogenesis is a deleterious effect on
cephalic neural-crest cell activity that results in the observed craniofacial,
cardiac, and thymic malformations.
DOI: 10.1056/NEJM198510033131401
PMID: 3162101 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/3162748
|
1. J Pediatr Ophthalmol Strabismus. 1988 Mar-Apr;25(2):60-6. doi:
10.3928/0191-3913-19880301-04.
Keratolenticular dysgenesis (Peters' anomaly) as a result of acute embryonic
insult during gastrulation.
Cook CS(1), Sulik KK.
Author information:
(1)Department of Anatomy and Ophthalmology, School of Medicine, University of
North Carolina, Chapel Hill 27599.
Keratolenticular dysgenesis (Peters' anomaly) was induced in mice by exposure to
the human teratogens, ethanol or 13-cis retinoic acid (isotretinoin, Accutane).
Acute teratogen exposure on the seventh day of gestation (corresponding to the
third week of human gestation) resulted in an eye malformation incidence of 46%
to 100% in day 14 fetuses. Of the abnormal eyes, 10% to 29% demonstrated failure
of detachment of the lens from the surface ectoderm. Delayed lens detachment was
seen as anterior lenticonus in 33% to 35% of the abnormal eyes. Abnormal lens
detachment appeared to result in mechanical interference with neural crest
migration to form the corneal stroma and endothelium, and iris stroma. This
secondary effect on neural crest derivatives is exhibited in the adult animals
as corneal opacities associated with defects in Descemet's membrane and
endothelium, and anterior polar cataracts.
DOI: 10.3928/0191-3913-19880301-04
PMID: 3162748 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/12832479
|
1. Mol Cell Biol. 2003 Jul;23(14):4939-47. doi: 10.1128/MCB.23.14.4939-4947.2003.
Critical contribution of the MDM2 acidic domain to p53 ubiquitination.
Kawai H(1), Wiederschain D, Yuan ZM.
Author information:
(1)Department of Cancer Cell Biology, Harvard School of Public Health, Boston,
Massachusetts 02115, USA.
MDM2 is an E3 ubiquitin ligase that targets p53 for proteasomal degradation.
Recent studies have shown, however, that the ring-finger domain (RFD) of MDM2,
where the ubiquitin E3 ligase activity resides, is necessary but not sufficient
for p53 ubiquitination, suggesting that an additional activity of MDM2 might be
required. To test this possibility, we generated a series of MDM2/MDMX chimeric
proteins to assess the contribution of each domain of MDM2 to the ubiquitination
process. MDMX is a close structural homolog of MDM2 that nevertheless lacks the
E3 ligase activity in vivo. We demonstrate here that MDMX gains
self-ubiquitination activity and becomes extremely unstable upon introduction of
the MDM2 RFD, indicating that the RFD is essential for self-ubiquitination. This
MDMX chimeric protein, however, is unable to ubiquitinate p53 in vivo despite
its E3 ligase activity and binding to p53, separating the self-ubiquitination
activity of MDM2 from its ability to ubiquitinate p53. Significantly, fusion of
the central acidic domain (AD) of MDM2 to the MDMX chimeric protein renders the
protein fully capable of ubiquitinating p53, and p53 ubiquitination is
associated with p53 degradation and nuclear export. Moreover, the AD mini
protein expressed in trans can functionally rescue the AD-lacking MDM2 mutant,
further supporting a critical role for the AD in MDM2-mediated p53
ubiquitination.
DOI: 10.1128/MCB.23.14.4939-4947.2003
PMCID: PMC162226
PMID: 12832479 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/15632057
|
1. Mol Cell Biol. 2005 Jan;25(2):545-53. doi: 10.1128/MCB.25.2.545-553.2005.
Regulation of p53 and MDM2 activity by MTBP.
Brady M(1), Vlatkovic N, Boyd MT.
Author information:
(1)MDM2/p53 Laboratory, Division of Surgery and Oncology, University of
Liverpool, 5th Floor, UCD Building, Daulby St., Liverpool L69 3GA, UK.
p53 is a critical coordinator of a wide range of stress responses. To facilitate
a rapid response to stress, p53 is produced constitutively but is negatively
regulated by MDM2. MDM2 can inhibit p53 in multiple independent ways: by binding
to its transcription activation domain, inhibiting p53 acetylation, promoting
nuclear export, and probably most importantly by promoting proteasomal
degradation of p53. The latter is achieved via MDM2's E3 ubiquitin ligase
activity harbored within the MDM2 RING finger domain. We have discovered that
MTBP promotes MDM2-mediated ubiquitination and degradation of p53 and also MDM2
stabilization in an MDM2 RING finger-dependent manner. Moreover, using small
interfering RNA to down-regulate endogenous MTBP in unstressed cells, we have
found that MTBP significantly contributes to MDM2-mediated regulation of p53
levels and activity. However, following exposure of cells to UV, but not
gamma-irradiation, MTBP is destabilized as part of the coordinated cellular
response. Our findings suggest that MTBP differentially regulates the E3
ubiquitin ligase activity of MDM2 towards two of its most critical targets
(itself and p53) and in doing so significantly contributes to MDM2-dependent p53
homeostasis in unstressed cells.
DOI: 10.1128/MCB.25.2.545-553.2005
PMCID: PMC543405
PMID: 15632057 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/18235222
|
1. Cell Cycle. 2008 Feb 1;7(3):287-92. doi: 10.4161/cc.7.3.5358. Epub 2007 Nov
25.
Unlocking the Mdm2-p53 loop: ubiquitin is the key.
Clegg HV(1), Itahana K, Zhang Y.
Author information:
(1)Lineberger Comprehensive Cancer Center and Curriculum in Genetics and
Molecular Biology, School of Medicine, the University of North Carolina, Chapel
Hill, North Carolina 27514, USA.
Mdm2 has been thought to regulate the tumor suppressor p53 in two ways: by
masking p53's access to transcriptional machinery, and by ubiquitinating p53,
targeting it for proteasomal degradation. This dogma was recently challenged by
data generated from knockin mice in which Mdm2's RING E3 ubiquitin ligase
activity was abrogated by a single point mutation. The RING mutant Mdm2 is fully
capable of binding with p53, yet cannot suppress p53 activity, suggesting that
Mdm2 cannot block p53 by binding alone, without ubiquitination. Data from the
RING knockin mice also revealed that endogenous Mdm2 does not, as previously
thought, regulate its own stability by self-ubiquitination. In this review, we
will discuss these findings and their relevance to the field, including
potential reasons for the discrepancies between previous data and that generated
by our knockin mice, as well as the feasibility of targeting Mdm2's E3 ubiquitin
ligase activity in cancer. We will also discuss additional research questions
that may be addressed using our mouse model.
DOI: 10.4161/cc.7.3.5358
PMID: 18235222 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/23559397
|
1. Am J Clin Dermatol. 2013 Apr;14(2):71-6. doi: 10.1007/s40257-013-0014-z.
Important controversies associated with isotretinoin therapy for acne.
Wolverton SE(1), Harper JC.
Author information:
(1)Department of Dermatology, Indiana University, 545 Barnhill Dr, Emerson Hall
139, Indianapolis, IN 46202, USA. swolvert@iupui.edu
Isotretinoin is a remarkably effective drug for severe, recalcitrant acne
vulgaris. Soon after the drug's release in the early 1980s, a number of
important adverse effects were reported subsequently leading to a variety of
medical and medicolegal controversies. Three of these controversies will be
highlighted concerning the putative role of isotretinoin in (1) depression and
suicide, (2) inflammatory bowel disease, and (3) iPledge and pregnancy
prevention programs. It appears that a very small subset of patients receiving
isotretinoin for acne are at risk for depression, which is very manageable
provided there is adequate patient awareness of the possibility, maximum
communication between the patient and physician, and cessation of therapy if
clinically important depression occurs (after which the depression rapidly
resolves in a week or less). Multiple controlled studies actually suggest a very
favorable effect of isotretinoin on depression and anxiety common in the
population requiring isotretinoin. With regard to inflammatory bowel disease, in
just one study, only ulcerative colitis association with isotretinoin reached
statistical significance. The actual incidence of this association is strikingly
low. Finally, it is clear that even the most recent pregnancy prevention program
(iPledge) is no more successful than prior programs; there will likely always be
a small number of female patients becoming pregnant while receiving isotretinoin
for acne vulgaris.
DOI: 10.1007/s40257-013-0014-z
PMID: 23559397 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/19961047
|
1. Eur Rev Med Pharmacol Sci. 2009 Sep-Oct;13(5):393-6.
Possible long-term teratogenic effect of isotretinoin in pregnancy.
Malvasi A(1), Tinelli A, Buia A, De Luca GF.
Author information:
(1)Department of Obstetrics and Gynaecology, Santa Maria Hospital, Bari, Italy.
The isotretinoin, a 13-cis-retinoic acid, has revolutionized the management of
severe treatment-resistant acne and it has been widely used for a range of
dermatological conditions, in 90% of the time in young women between 13 and 45
years of age. This agent has severe teratogenic effects, as serious
craniofacial, cardiovascular, thymic and central nervous system malformations.
The baseline population risk of malformations is 3-5%, but it increases to
almost 30% in women exposed to isotretinoin during the first trimester of
pregnancy. Generally, patients in treatment with isotretinoin avoid eventual
pregnancy during assumption and, after its stopping, fertility and foetal
development are normal once circulating isotretinoin levels return to normal.
There are no known deleterious effects on male fertility and on long-term
teratogenic effect of isotretinoin. In this report, we suppose the possibility
to develop a foetal malformations after a long-term wash out from isotretinoin
therapy. A 32 year-old healthy nullipara pregnant woman, with an uneventful past
gynaecological history, was admitted in Hospital, with a severe depressive
syndrome in a 18 weeks malformed pregnancy for thoraco-omphalopagus conjoined
twins. She only assumed isotretinoin, at dose of 1 mg/kg a day, for a severe and
scarring acne for 7 months. After 3 months of pharmacological wash out, patient
become pregnant and manifested this severe malformation. Woman interrupted
gestation, by labour induction.
PMID: 19961047 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/17214828
|
1. Br J Clin Pharmacol. 2007 Feb;63(2):196-205. doi:
10.1111/j.1365-2125.2006.02837.x.
Isotretinoin, pregnancies, abortions and birth defects: a population-based
perspective.
Bérard A(1), Azoulay L, Koren G, Blais L, Perreault S, Oraichi D.
Author information:
(1)Faculty of Pharmacy, University of Montreal, CHU Sainte-Justine, Montreal,
QC, Canada. anick.berard@umontreal.ca
Comment in
Br J Clin Pharmacol. 2009 Jan;67(1):137-8. doi:
10.1111/j.1365-2125.2008.03235.x.
AIMS: To estimate the population-based incidence rates of pregnancy, spontaneous
and elective abortions, and birth defects associated with isotretinoin use, and
to determine predictors of pregnancy while on isotretinoin.
METHODS: Using the RAMQ (medical and pharmaceutical data), MED-ECHO
(hospitalizations) and ISQ (births and deaths) databases for the period
1984-2002, a cohort of 8609 women between 13 and 45 years of age and with a
first prescription for isotretinoin (date of entry in the cohort) was
identified. Women were eligible if they were insured by RAMQ for their
medications at least 12 months before entry in the cohort and until 1 month
after the end of their isotretinoin treatment. Pregnancies, spontaneous and
elective abortions, and birth defects were identified using procedure codes and
medical diagnoses.
RESULTS: Of the 8609 women included, 90 became pregnant, an annual incident
pregnancy rate during isotretinoin treatment of 32.7 per 1000 person-years of
treatment (95% confidence interval 26.6, 40.1). Of the 90 women who became
pregnant while on the drug, 76 terminated the pregnancy (84%), three had a
spontaneous abortion (3%), two had trauma during delivery resulting in neonatal
deaths (2%) and nine had a live birth (10%). Among the live births, only one had
a congenital anomaly of the face and neck (11%). Adjusting for potential
confounders, predictors of becoming pregnant while on isotretinoin were lower
socio-economic level, one or more visits to the doctor or to the emergency
department, or one or more hospitalization while on isotretinoin; concomitant
isotretinoin and oral contraceptive use had a preventive effect.
CONCLUSIONS: This first non-interventional population-based study generated
incidence rates of pregnancy while on isotretinoin four times greater than what
has been reported in the literature thus far; elective abortion rates were also
much higher in our study. This shows the importance of using population-based
data for public health purposes.
DOI: 10.1111/j.1365-2125.2006.02837.x
PMCID: PMC1859978
PMID: 17214828 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/3459732
|
1. J Craniofac Genet Dev Biol. 1986;6(2):99-112.
Isotretinoin teratogenicity in mouse whole embryo culture.
Goulding EH, Pratt RM.
Recent clinical observations strongly suggest that isotretinoin [13-cis-retinoic
acid (cis RA)] is a human teratogen causing primarily heart and craniofacial
malformations including ear and palatal defects. The purpose of the present
study was to determine if cis RA could induce similar craniofacial malformations
in mouse embryo culture. Day 8 CD-1 mouse embryos were cultured for 48 hours in
rat serum in the presence or absence of various concentrations of cis RA
dissolved in DMSO. DMSO by itself had no effect on embryonic development;
however, cis RA at 2 X 10(-5) M (6 micrograms/ml) was clearly toxic. At 2 X
10(-6) M cis RA, growth retardation was minimal, and approximately one-third of
the embryos exhibited very specific defects including a dramatic reduction in
the size of the first and second visceral arches, which eventually give rise to
the maxilla, mandible, and ear. Similar observations were also made with
4-oxo-13-cis RA, which is a major metabolite of cis RA in the mouse and human.
These malformations would be expected to result in defects similar to those
observed in the human, and preliminary observations suggest these defects are
due to cis RA-induced inhibition of cranial neural crest cell migration. Using
day-10 mouse embryos cultured for 48 hours in Waymouth's medium containing 50%
fetal calf serum, we observed that cis RA at 2 X 10(-5) M produced a high
percentage of embryos with limb defects and median cleft lip. Our results
demonstrate that labeled cis RA enters the tissues of the embryo both in vivo
and in vitro. Cis RA inhibited proliferation of the frontonasal mesenchyme cells
in primary culture with 31% inhibition occurring at 2 X 10(-5) M cis RA.
PMID: 3459732 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/21198520
|
1. Australas J Dermatol. 2010 Nov;51(4):248-53. doi:
10.1111/j.1440-0960.2010.00657.x.
Adverse effects of isotretinoin: A retrospective review of 1743 patients started
on isotretinoin.
Rademaker M(1).
Author information:
(1)Tristram Clinic, Hamilton, New Zealand. rademaker@xtra.co.nz
Comment in
Australas J Dermatol. 2011 May;52(2):147-8; author reply 148. doi:
10.1111/j.1440-0960.2011.00764.x.
BACKGROUND/OBJECTIVES: Isotretinoin has revolutionized the management of acne
vulgaris. However, concerns continue regarding the adverse effect profile of
isotretinoin. This study aims to review the adverse effects experienced by
patients started on isotretinoin by a single dermatologist.
METHODS: Retrospective chart review of 1743 patients started on isotretinoin for
various dermatological conditions over a 6-year period. Details of the dose of
isotretinoin used, concomitant medications, adverse effects and outcome were
recorded.
RESULTS: One-fifth (18.5%) of patients reported no adverse effects during the
study period. Cheilitis was the most commonly reported adverse effect, affecting
78% of users, followed by eczema and tiredness, seen in 12% each. However, these
were clearly dose-dependent, as the group treated with doses of isotretinoin
under 0.25 mg/kg/day only reported cheilitis in 47%, eczema in 7% and tiredness
in 5%, compared with 96%, 16% and 18%, respectively, in those treated with more
than 0.75 mg/gm/day. Twenty-four patients (1.4%) stopped isotretinoin because of
adverse effects; a further three patients complained of severe adverse effects
on at least one occasion, but continued taking the medication. The adverse
effect(s) that led to patients stopping isotretinoin were cheilitis (22
patients), mood change (13), tiredness (12), eczema (6) and pregnancy (2). There
were no reported instances of suicidal ideation or attempted suicide.
CONCLUSIONS: Other than the two oral contraceptive failures, there were no
serious adverse events recorded during this review period. Isotretinoin is a
very effective medication with a low adverse-effect profile when used at lower
doses.
© 2010 The Author. Australasian Journal of Dermatology © 2010 The Australasian
College of Dermatologists.
DOI: 10.1111/j.1440-0960.2010.00657.x
PMID: 21198520 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/22666487
|
1. PLoS One. 2012;7(5):e38212. doi: 10.1371/journal.pone.0038212. Epub 2012 May
29.
Mdm2 RING mutation enhances p53 transcriptional activity and p53-p300
interaction.
Clegg HV(1), Itahana Y, Itahana K, Ramalingam S, Zhang Y.
Author information:
(1)Lineberger Comprehensive Cancer Center, School of Medicine, University of
North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of
America.
The p53 transcription factor and tumor suppressor is regulated primarily by the
E3 ubiquitin ligase Mdm2, which ubiquitinates p53 to target it for proteasomal
degradation. Aside from its ubiquitin ligase function, Mdm2 has been believed to
be capable of suppressing p53's transcriptional activity by binding with and
masking the transactivation domain of p53. The ability of Mdm2 to restrain p53
activity by binding alone, without ubiquitination, was challenged by a 2007
study using a knockin mouse harboring a single cysteine-to-alanine point
mutation (C462A) in Mdm2's RING domain. Mouse embryonic fibroblasts with this
mutation, which abrogates Mdm2's E3 ubiquitin ligase activity without affecting
its ability to bind with p53, were unable to suppress p53 activity. In this
study, we utilized the Mdm2(C462A) mouse model to characterize in further detail
the role of Mdm2's RING domain in the control of p53. Here, we show in vivo that
the Mdm2(C462A) protein not only fails to suppress p53, but compared to the
complete absence of Mdm2, Mdm2(C462A) actually enhances p53 transcriptional
activity toward p53 target genes p21/CDKN1A, MDM2, BAX, NOXA, and 14-3-3σ. In
addition, we found that Mdm2(C462A) facilitates the interaction between p53 and
the acetyltransferase CBP/p300, and it fails to heterodimerize with its homolog
and sister regulator of p53, Mdmx, suggesting that a fully intact RING domain is
required for Mdm2's inhibition of the p300-p53 interaction and for its
interaction with Mdmx. These findings help us to better understand the complex
regulation of the Mdm2-p53 pathway and have important implications for
chemotherapeutic agents targeting Mdm2, as they suggest that inhibition of
Mdm2's E3 ubiquitin ligase activity may be sufficient for increasing p53
activity in vivo, without the need to block Mdm2-p53 binding.
DOI: 10.1371/journal.pone.0038212
PMCID: PMC3362553
PMID: 22666487 [Indexed for MEDLINE]
Conflict of interest statement: Competing Interests: The authors have declared
that no competing interests exist.
|
http://www.ncbi.nlm.nih.gov/pubmed/2923442
|
1. Arch Dermatol. 1989 Mar;125(3):362-5.
Safety of pregnancy after discontinuation of isotretinoin.
Dai WS(1), Hsu MA, Itri LM.
Author information:
(1)Department of Drug Safety, Hoffmann-La Roche Inc, Nutley, NJ 07110.
Isotretinoin (13-cis-retinoic acid, Accutane) increases the risk of major
congenital malformations in infants exposed to isotretinoin during pregnancy.
However, there have been no epidemiologic reports to date on the effect of a
subsequent pregnancy after discontinuation of isotretinoin. This article
describes our analysis of pregnancy case reports from patients in whom
conception occurred after isotretinoin treatment had been discontinued. Based on
the 88 prospectively ascertained cases, the incidence rate of both spontaneous
and missed abortions from all pregnancies was 9.1% (eight patients), and the
incidence rate of congenital malformation among the live births was 5.0% (four
patients). The incidence rates for both these outcomes were not significantly
different from the rates reported for women of reproductive age in the general
population. In addition, the malformations reported were not characteristic of
retinoic acid-induced congenital anomalies.
PMID: 2923442 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/21075307
|
1. Cancer Cell. 2010 Nov 16;18(5):411-22. doi: 10.1016/j.ccr.2010.10.024.
A stapled p53 helix overcomes HDMX-mediated suppression of p53.
Bernal F(1), Wade M, Godes M, Davis TN, Whitehead DG, Kung AL, Wahl GM, Walensky
LD.
Author information:
(1)Department of Pediatric Oncology, Dana-Farber Cancer Institute and Children's
Hospital Boston, Harvard Medical School, Boston, MA 02115, USA.
Comment on
Cancer Cell. 2010 Nov 16;18(5):399-400. doi: 10.1016/j.ccr.2010.10.026.
Cancer cells neutralize p53 by deletion, mutation, proteasomal degradation, or
sequestration to achieve a pathologic survival advantage. Targeting the E3
ubiquitin ligase HDM2 can lead to a therapeutic surge in p53 levels. However,
the efficacy of HDM2 inhibition can be compromised by overexpression of HDMX, an
HDM2 homolog that binds and sequesters p53. Here, we report that a stapled p53
helix preferentially targets HDMX, blocks the formation of inhibitory p53-HDMX
complexes, induces p53-dependent transcriptional upregulation, and thereby
overcomes HDMX-mediated cancer resistance in vitro and in vivo. Importantly, our
analysis of p53 interaction dynamics provides a blueprint for reactivating the
p53 pathway in cancer by matching HDM2, HDMX, or dual inhibitors to the
appropriate cellular context.
Copyright © 2010 Elsevier Inc. All rights reserved.
DOI: 10.1016/j.ccr.2010.10.024
PMCID: PMC3050021
PMID: 21075307 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/19934289
|
1. Clin Cancer Res. 2009 Dec 1;15(23):7153-60. doi:
10.1158/1078-0432.CCR-09-1071. Epub 2009 Nov 24.
Interactions of the Hdm2/p53 and proteasome pathways may enhance the antitumor
activity of bortezomib.
Ooi MG(1), Hayden PJ, Kotoula V, McMillin DW, Charalambous E, Daskalaki E, Raje
NS, Munshi NC, Chauhan D, Hideshima T, Buon L, Clynes M, O'Gorman P, Richardson
PG, Mitsiades CS, Anderson KC, Mitsiades N.
Author information:
(1)Medical Oncology, Jerome Lipper Multiple Myeloma Center, Dana Farber Cancer
Institute, Boston, Massachusetts 02115, USA.
PURPOSE: p53 is inactivated in many human malignancies through missense
mutations or overexpression of the human homologue of Mdm2 (Hdm2), an E3
ubiquitin ligase that ubiquitinates p53, thereby promoting its proteasomal
degradation. The cis-imidazoline nutlin-3 can disrupt the p53-Hdm2 interaction
and activate p53, inducing apoptosis in vitro in many malignancies, including
multiple myeloma (MM).
EXPERIMENTAL DESIGN: We hypothesized that suppression of Hdm2-mediated p53
ubiquitination may augment sequelae of p53 accumulation caused by proteasomal
inhibition. We compared the response of MM cells versus several epithelial
cancer models to the proteasome inhibitor bortezomib in combination with
nutlin-3.
RESULTS: The combination of sublethal concentrations of bortezomib plus nutlin-3
induced additive cytotoxicity against bortezomib-sensitive MM cell lines.
Importantly, however, in breast, prostate, colon, and thyroid (papillary,
follicular, anaplastic, and medullary) carcinoma cell lines, this combination
triggered synergistic cytotoxicity, and increased expression of p53, p21, Hdm2,
Bax, Noxa, PUMA, and cleavage of caspase-3 and poly ADP ribose polymerase.
Coculture with bone marrow stromal cells attenuated MM cell sensitivity to
nutlin-3 monotherapy and was associated with evidence of suppression of p53
activity in MM cells, whereas combined bortezomib-nutlin-3 treatment maintained
cytotoxicity even in the presence of bone marrow stromal cells.
CONCLUSIONS: This differential response of MM versus epithelial carcinomas to
combination of nutlin-3 with bortezomib sheds new light on the role of p53 in
bortezomib-induced apoptosis. Concurrent Hdm2 inhibition with bortezomib may
extend the spectrum of bortezomib applications to malignancies with currently
limited sensitivity to single-agent bortezomib or, in the future, to MM patients
with decreased clinical responsiveness to bortezomib-based therapy.
DOI: 10.1158/1078-0432.CCR-09-1071
PMCID: PMC3672410
PMID: 19934289 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/3501432
|
1. J Craniofac Genet Dev Biol. 1987;7(3):241-65.
Human embryonic palatal epithelial differentiation is altered by retinoic acid
and epidermal growth factor in organ culture.
Abbott BD(1), Pratt RM.
Author information:
(1)Experimental Teratogenesis Section, National Institute of Environmental
Health Sciences, Research Triangle Park, NC 27709.
Reports of adverse human pregnancy outcomes including cleft palate have
increased as the clinical use of isotretinoin (13-cis-retinoic acid) and other
retinoic acid (RA) derivatives have increased, but the mechanisms by which their
effects are exerted are not understood. Research in craniofacial development is
generally performed in rodents, and mouse palatal shelves exposed in organ
cultures to retinoids and epidermal growth factor (EGF) display altered medial
epithelial cell morphology blocking normal union of apposing shelves. In the
present study, precontacting human palatal shelves were maintained in organ
culture for 2, 3, or 6 days and exposed to labeled thymidine (3H-TdR) during the
last 16 hr. Retinoids and EGF were included in the media so that each shelf was
exposed to one of the following: control, EGF, trans-RA at 10(-5)M, cis-RA at
10(-7) or 10(-9) M, or RA + EGF. After exposure of cultured human embryonic
palatal shelves to 13-cis-RA and trans-RA with or without EGF, medial epithelial
cells do not degenerate, cell surface morphology shifts toward a nasal type,
glycogen deposits decrease, smooth endoplasmic reticulum (SER) increases, and
basal lamina appear altered. In shelves exposed to EGF and trans-RA early in
their development, DNA synthesis appears to terminate prematurely as compared to
shelves cultured in control media, and this effect is accompanied by excessive
mesenchymal extracellular space expansion. Exposure of shelves to EGF alone is
sufficient to block degeneration and induce hyperplasia of the medial epithelial
cells but does not induce other ultrastructural changes seen with both EGF and
RA. The observed alterations in medial cell morphology could interfere with
adhesion of the palatal shelves and may play a role in retinoid-induced cleft
palate in the human embryo.
PMID: 3501432 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/7525959
|
1. J Med Chem. 1994 Oct 28;37(22):3819-27. doi: 10.1021/jm00048a017.
Inhibition of topoisomerase II catalytic activity by pyridoacridine alkaloids
from a Cystodytes sp. ascidian: a mechanism for the apparent
intercalator-induced inhibition of topoisomerase II.
McDonald LA(1), Eldredge GS, Barrows LR, Ireland CM.
Author information:
(1)Department of Medicinal Chemistry, University of Utah, Salt Lake City 84112.
Several new pyridoacridine alkaloids, dehydrokuanoniamine B (1), shermilamine C
(2), and cystodytin J (3), in addition to the known compounds cystodytin A (4),
kuanoniamine D (5), shermilamine B (6), and eilatin (7), were isolated from a
Fijian Cystodytes sp. ascidian. Their structures were determined by analyses of
spectroscopic data. These compounds along with a previously reported
pyridoacridine, diplamine (8), showed dose-dependent inhibition of proliferation
in human colon tumor (HCT) cells in vitro. All compounds inhibited the
topoisomerase (TOPO) II-mediated decatenation of kinetoplast DNA (kDNA) in a
dose-dependent manner. The pyridoacridines' ability to inhibit TOPO II-mediated
decatenation of kDNA correlated with their cytotoxic potencies and their ability
to intercalate into calf thymus DNA. These results suggest that disruption of
the function of TOPO II, subsequent to intercalation, is a probable mechanism by
which pyridoacridines inhibit the proliferation of HCT cells. Incorporation
studies show that pyridoacridines disrupt DNA and RNA synthesis with little
effect on protein synthesis. It appears that DNA is the primary cellular target
of the pyridoacridine alkaloids. These results are consistent with those for
known DNA intercalators.
DOI: 10.1021/jm00048a017
PMID: 7525959 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/16082221
|
1. Cell Cycle. 2005 Sep;4(9):1166-70. doi: 10.4161/cc.4.9.1981. Epub 2005 Sep 29.
ATM-mediated phosphorylations inhibit Mdmx/Mdm2 stabilization by HAUSP in favor
of p53 activation.
Meulmeester E(1), Pereg Y, Shiloh Y, Jochemsen AG.
Author information:
(1)Department of Molecular and Cell Biology, Leiden University Medical Center,
Leiden, The Netherlands.
The p53 tumor suppressor protein has a major role in protecting genome
integrity. Under normal circumstances Mdmx and Mdm2 control the activity of p53.
Both proteins inhibit the transcriptional regulation by p53, while Mdm2 also
functions as an E3 ubiquitin ligase to target both p53 and Mdmx for proteasomal
degradation. HAUSP counteracts the destabilizing effect of Mdm2 by direct
deubiquitination of p53. Subsequently, HAUSP was shown to deubiquitinate Mdm2
and Mdmx, thereby stabilizing these proteins. The ATM protein kinase is a key
regulator of the p53 pathway in response to double strand breaks (DSBs) in the
DNA. ATM fine-tunes p53's response to DNA damage by directly phosphorylating it,
by regulating additional post-translational modifications of this protein, and
by affecting two p53 regulators: Mdm2 and Mdmx. ATM directly and indirectly
induces Mdm2 and Mdmx phosphorylation, resulting in decreased activity and
stability of these proteins. We recently provided a mechanism for the reduced
stability of Mdm2 and Mdmx by showing that ATM-dependent phosphorylation lowers
their affinity for the deubiquitinating enzyme HAUSP. Altogether, the emerging
picture portrays an elaborate, but fine-tuned, ATM-mediated control of p53
activation and stabilization following DNA damage. Further insight into the
mechanism by which ATM switches the interactions between HAUSP, Mdmx, Mdm2 and
p53, to favor p53 activation may offer new tools for therapeutic intervention in
the p53 pathway for cancer treatment.
DOI: 10.4161/cc.4.9.1981
PMID: 16082221 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/9299599
|
1. Toxicol Appl Pharmacol. 1997 Sep;146(1):79-87. doi: 10.1006/taap.1997.8220.
Embryonic delivered dose of isotretinoin (13-cis-retinoic acid) and its
metabolites in hamsters.
Eckhoff C(1), Willhite CC.
Author information:
(1)Hoffmann-La Roche, Inc., 340 Kingsland Street, Nutley, New Jersey 07110, USA.
All-trans-retinoic acid (all-trans-RA) is required in normal embryogenesis and
both deficiency and excess are teratogenic. Isotretinoin (13-cis-RA) is
teratogenic in all species examined; based on administered dose, humans appear
most sensitive, followed by (in order or decreasing sensitivity) monkey, rabbit,
hamster, mouse, and rat. Identification of the teratogenic threshold in these
species is difficult because RAs are normal physiologic constituents. The rabbit
no-observed-adverse-effect-level (NOAEL) and
lowest-observed-adverse-effect-level (LOAEL) administered doses (3 and 15
mg/kg/day, respectively, on gestation Days 8-11) are less than the corresponding
values in hamster (7.5 and 37.5 mg/kg/day, respectively, on gestation Days 7 and
8), but drawing conclusions from administered dose alone ignores differences in
absorbed, metabolized, and embryonic delivered dose. Therefore, distribution and
metabolism studies of 13-cis-RA at the NOAEL and LOAEL in pregnant hamsters were
performed and plasma and tissue concentrations of parent compound and
metabolites were compared to those found in rabbits. Metabolites of 13-cis-RA
common to all species include three RAs (all-trans-RA, all-trans-4-oxoRA,
13-cis-4-oxoRA) and the glucuronide conjugate of 13-cis-RA (13-cis-RAG). As in
rabbits, we found 13-cis-4-oxoRA also to be the major metabolite of 13-cis-RA in
hamster plasma, peripheral tissues, and embryo. Of maternal tissues, peak
13-cis-RA concentrations were highest in liver. Total concentration of RA
(13-cis-RA + 13-cis-4-oxoRA + all-trans-RA + all-trans-4-oxoRA) per gram of wet
tissue was greatest in maternal liver, followed by that in lung, adipose tissue,
muscle, kidney, and brain. At the NOAEL, total RA plasma Cmax in hamster was 6
times that in rabbit; at the LOAEL, hamster plasma total RA Cmax was 4 times
that in rabbit. Hamster absorbed and metabolized dose (as AUC of plasma total
RA) at the NOAEL and LOAEL was 2.6 and 2.4 times that in rabbit, respectively.
In the embryo, hamster total RA Cmax was 2.7 times (at NOAEL) and 2.6 times (at
LOAEL) that in rabbit. However, embryonic delivered dose (total RA AUC in
hamster and rabbit embryo, respectively) at the NOAEL (2.08 and 2.14 microg .
hr.g-1) and LOAEL (5.34 and 5.54 microg . hr . g-1) was virtually identical.
Embryonic AUCs in hamster and rabbit for all-trans-RA and all-trans-4-oxoRA,
metabolites which transactivate directly the nuclear RA receptors (RARs), were
also very similar at the NOAEL (0.66 and 0.81 microg . hr g-1) and at the LOAEL
(1.14 and 1.32 microg . hr g-1). Based on embryonic delivered dose, we suggest
that 13-cis-RA is an equipotent teratogen in hamster and rabbit.
Copyright 1997 Academic Press.
DOI: 10.1006/taap.1997.8220
PMID: 9299599 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/22819825
|
1. FEBS Lett. 2012 Sep 21;586(19):3057-63. doi: 10.1016/j.febslet.2012.07.022.
Epub 2012 Jul 20.
TRIAD1 inhibits MDM2-mediated p53 ubiquitination and degradation.
Bae S(1), Jung JH, Kim K, An IS, Kim SY, Lee JH, Park IC, Jin YW, Lee SJ, An S.
Author information:
(1)Molecular-Targeted Drug Research Centre, Konkuk University, Seoul, Republic
of Korea.
Murine double minute (MDM2) is an E3 ligase that promotes ubiquitination and
degradation of tumor suppressor protein 53 (p53). MDM2-mediated regulation of
p53 has been investigated as a classical tumorigenesis pathway. Here, we
describe TRIAD1 as a novel modulator of the p53-MDM2 axis that induces p53
activation by inhibiting its regulation by MDM2. Ablation of TRIAD1 attenuates
p53 levels activity upon DNA damage, whereas ectopic expression of TRIAD1
promotes p53 stability by inhibiting MDM2-mediated ubiquitination/degradation.
Moreover, TRIAD1 binds to the C-terminus of p53 to promote its dissociation from
MDM2. These results implicate TRIAD1 as a novel regulatory factor of p53-MDM2.
Copyright © 2012 Federation of European Biochemical Societies. Published by
Elsevier B.V. All rights reserved.
DOI: 10.1016/j.febslet.2012.07.022
PMID: 22819825 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/17442658
|
1. Ann Oncol. 2007 Jun;18(6):1098-103. doi: 10.1093/annonc/mdm120. Epub 2007 Apr
17.
The use of pharmacokinetic and pharmacodynamic end points to determine the dose
of AQ4N, a novel hypoxic cell cytotoxin, given with fractionated radiotherapy in
a phase I study.
Steward WP(1), Middleton M, Benghiat A, Loadman PM, Hayward C, Waller S, Ford S,
Halbert G, Patterson LH, Talbot D.
Author information:
(1)Department of Oncology, Leicester Royal Infirmary, Leicester, UK.
wps1@le.ac.uk
BACKGROUND: AQ4N (1,4-bis[[2-(dimethylamino)ethyl]
amino]-5,8-dihydroxyanthracene-9, 10-dione bis-N-oxide dihydrochloride) is a
prodrug which is selectively activated within hypoxic tissues to AQ4, a
topoisomerase II inhibitor and DNA intercalator.
PATIENTS AND METHODS: In the phase I study, 22 patients with oesophageal
carcinoma received an i.v. infusion of AQ4N (22.5-447 mg/m(2)) followed, 2 weeks
later, by further infusion and radiotherapy. Pharmacokinetics and lymphocyte
AQ4N and AQ4 levels were measured after the first dose. At 447 mg/m(2), biopsies
of tumour and normal tissue were taken after AQ4N administration.
RESULTS: Drug-related adverse events were blue discolouration of skin and urine,
grade 2-3 lymphopenia, grade 1-3 fatigue, grade 1-2 anaemia, leucopenia and
nausea. There were no drug-related serious adverse events (SAEs). Three patients
had reductions in tumour volume >50%, nine had stable disease. Pharmacokinetics
indicated predictable clearance. Plasma area under the curve (AUC) at 447
mg/m(2) exceeded AQ4N concentrations in mice at therapeutic doses and tumour
biopsies contained concentrations of AQ4 greater than those in normal tissue.
Tumour concentrations of AQ4 exceeded in vitro IC(50) values for most cell lines
investigated.
CONCLUSIONS: No dose-limiting toxic effects were observed and a maximum
tolerated dose was not established. Tumour AQ4 concentrations and plasma AUC at
447 mg/m(2) exceeded active levels in preclinical models. This dose was chosen
for future studies with radiotherapy.
DOI: 10.1093/annonc/mdm120
PMID: 17442658 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/17433851
|
1. Eur J Med Chem. 2007 Jun;42(6):752-71. doi: 10.1016/j.ejmech.2006.12.039. Epub
2007 Mar 2.
Design, synthesis and biological evaluation of new oligopyrrole carboxamides
linked with tricyclic DNA-intercalators as potential DNA ligands or
topoisomerase inhibitors.
David-Cordonnier MH(1), Hildebrand MP, Baldeyrou B, Lansiaux A, Keuser C,
Benzschawel K, Lemster T, Pindur U.
Author information:
(1)INSERM U837-JPARC, Equipe N degrees 4, Institut de Recherches sur le Cancer
de Lille, Place de Verdun, 59045 Lille Cedex, France.
In the context of the design and synthesis of minor groove binding and
intercalating DNA ligands some new oligopyrrole carboxamides were synthesized.
These hybrid molecules (combilexins) possess a variable and conformatively
flexible spacer at the N-terminal end. As intercalating tricyclic systems
acridone, acridine, anthraquinones and in a special case iminostilbene terminate
the N-terminal end of the pyrrole chain. The cytotoxicity was examined by the
NCI antitumor screening, furthermore, biophysical as well as biochemical studies
were performed in order to get some information about the DNA binding properties
and topoisomerase inhibition effect of this new series of molecules.
DOI: 10.1016/j.ejmech.2006.12.039
PMID: 17433851 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/2536704
|
1. J Biol Chem. 1989 Feb 5;264(4):2324-30.
DNA intercalation and inhibition of topoisomerase II. Structure-activity
relationships for a series of amiloride analogs.
Besterman JM(1), Elwell LP, Cragoe EJ Jr, Andrews CW, Cory M.
Author information:
(1)Department of Molecular Biology, Wellcome Research Laboratories, Research
Triangle Park, North Carolina 27709.
Among its many properties, amiloride is a DNA intercalator and topoisomerase II
inhibitor. Previous work has indicated that the most stable conformation for
amiloride is a planar, hydrogen-bonded, tricyclic structure. To determine
whether the ability of amiloride to intercalate into DNA and to inhibit DNA
topoisomerase II was dependent on the ability to assume a cyclized conformation,
we studied the structure-activity relationship for 12 amiloride analogs. These
analogs contained structural modifications which could be expected to allow or
impede formation of a cyclized conformation. Empirical assays consisting of
biophysical, biochemical, and cell biological approaches, as well as
computational molecular modeling approaches, were used to determine
conformational properties for these molecules, and to determine whether they
intercalated into DNA and inhibited topoisomerase II. Specifically, we measured
the ability of these compounds to 1) alter the thermal denaturation profile of
DNA, 2) modify the hydrodynamic behavior of DNA, 3) inhibit the catalytic
activity of purified DNA topoisomerase II in vitro, 4) promote the topoisomerase
II-dependent cleavage of DNA, and 5) inhibit functions associated with DNA
topoisomerase II in intact cells. Results indicated that only those analogs
capable of cyclization could intercalate into DNA and inhibit topoisomerase II.
Thus, the ability of amiloride and the 12 analogs studied to intercalate into
DNA and to inhibit topoisomerase II appears dependent on the ability to exist in
a planar, hydrogen-bonded, tricyclic conformation.
PMID: 2536704 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/3009009
|
1. Cancer Res. 1986 Jun;46(6):3075-81.
Altered DNA topoisomerase II activity in Chinese hamster cells resistant to
topoisomerase II inhibitors.
Pommier Y, Kerrigan D, Schwartz RE, Swack JA, McCurdy A.
Most DNA intercalators and epipodophyllotoxins inhibit mammalian topoisomerase
II by trapping the enzyme within DNA cleavage complexes that can be detected in
cells as protein-associated DNA strand breaks. We have characterized previously
a line of Chinese hamster cells (DC3F/9-OHE cells) the resistance of which to
the cytotoxic effect of intercalators and etoposide is associated with a reduced
formation of protein-associated DNA strand breaks. In the present study,
topoisomerases of these cells were compared to those of the parental sensitive
cells (DC3F). NaCl extracts (0.35 M) of isolated DC3F/9-OHE nuclei did not form
4'-(9-acridinylamino)methanesulfon-m-anisidide-induced DNA-protein linking,
whereas DC3F nuclear extracts did. In addition, DC3F/9-OHE nuclear extract had
an unusually high level of DNA linking activity in the absence of
4'-(9-acridinylamino)methanesulfon-m-anisidide. Topoisomerases II from
DC3F/9-OHE and DC3F nuclei appeared similar qualitatively. DC3F/9-OHE nuclear
extract had approximately twice less topoisomerase II molecules than did DC3F
nuclear extract but similar topoisomerase II activity. Topoisomerase I
activities appeared also similar in sensitive and resistant cells. However, part
of DC3F/9-OHE topoisomerase I copurified with a DNA linking activity which was
not present in DC3F nuclei. This unusual DNA linking activity was not sensitive
to the stimulatory effect of 4'-(9-acridinylamino)methanesulfon-m-anisidide.
PMID: 3009009 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/1727386
|
1. Cancer Res. 1992 Jan 1;52(1):5-10.
Activation of the gadd153 promoter by genotoxic agents: a rapid and specific
response to DNA damage.
Luethy JD(1), Holbrook NJ.
Author information:
(1)Laboratory of Molecular Genetics, Gerontology Research Center, National
Institute on Aging, Baltimore, Maryland 21224.
Accumulation of gadd153 mRNA is strongly stimulated in mammalian cells by
treatments which arrest growth or damage DNA (A. J. Fornace, Jr. et al., Mol.
Cell. Biol., 9: 4196-4203, 1989). In previous studies, we demonstrated that the
increased expression of gadd153 following treatment with several DNA-damaging
agents was mediated transcriptionally (J. D. Luethy et al., J. Biol. Chem., 265:
16521-16526, 1990). To better define the specificity of this response, we have
established a sensitive reporter system in which we have stably integrated a
chimeric gene containing the gadd153 promoter linked to the coding region of the
chloramphenicol acetyltransferase (CAT) gene into the genome of HeLa cells.
Transcriptional activation from the gadd153 promoter was monitored by
determining levels of CAT activity in cellular lysates prepared from
gadd153CAT/HeLa cells treated with a variety of agents. The gadd153 promoter was
strongly activated by a broad spectrum of genotoxic agents including UV-mimetic
agents, DNA-cross-linking and alkylating agents, DNA intercalators, and
topoisomerase inhibitors. Of the DNA-damaging agents tested, only X-irradiation
and bleomycin treatments failed to induce gadd153 promoter activity. Agents
which inhibit replication and cell division and agents which otherwise result in
cytotoxicity or growth arrest also had little influence on gadd153 promoter
activity. Expression of the gadd153CAT chimeric gene in xeroderma pigmentosum
Group A cells, which are deficient in nucleotide excision DNA repair of
pyrimidine dimers, was maximally induced at UV doses at least 6-fold lower than
those required for similar induction in repair-proficient HeLa cells. However,
the methyl methanesulfonate-induced gadd153 promoter activities were similar in
both cell lines. Novobiocin pretreatment inhibited both UV- and methyl
methanesulfonate-induced gadd153CAT expression. Collectively, these data
indicate that: (a) the gadd153 promoter is activated rapidly and specifically by
DNA damage; (b) the altered DNA structure is the inducing signal for the
activation of the signal transduction pathway responsible for enhanced gadd153
expression; and (c) regulation of gadd153 by growth arrest is distinct from that
of DNA damage. Thus, the gadd153CAT/HeLa cells are a useful model for examining
the molecular mechanisms associated with the response to DNA damage and provide
a reporter system for the screening of potential genotoxic agents.
PMID: 1727386 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/19424733
|
1. J Mol Model. 2009 Dec;15(12):1417-26. doi: 10.1007/s00894-009-0501-6. Epub
2009 May 8.
Quinoline alkaloids as intercalative topoisomerase inhibitors.
Byler KG(1), Wang C, Setzer WN.
Author information:
(1)Department of Chemistry, University of Alabama in Huntsville, 35899, USA.
Quinoline alkaloids are abundant in the Rutaceae, and many have exhibited
cytotoxic activity. Because structurally related antitumor alkaloids such as
camptothecin and fagaronine are known to function as intercalative topoisomerase
poisons, it is hypothesized that cytotoxic Stauranthus alkaloids may also serve
as intercalative topoisomerase inhibitors. To test this hypothesis
theoretically, ten Stauranthus quinoline alkaloids were examined for potential
intercalation into DNA using a molecular docking approach. Four of the alkaloids
(stauranthine, skimmianine, 3',6'-dihydroxy-3',6'-dihydrostauranthine, and
trans-3',4'-dihydroxy-3',4'-dihydrostauranthine) were able to intercalatively
dock consistently into DNA. In order to probe the intermolecular interactions
that may be responsible for intercalation of these quinoline alkaloids, density
functional calculations have been carried out using both the B3LYP and M06
functionals. M06 calculations indicated favorable pi-pi interactions between
either skimmianine or stauranthine and the guanine-cytosine base pair.
Furthermore, the lowest-energy face-to-face orientation of stauranthine with
guanine is consistent with favorable dipole-dipole orientations, favorable
electrostatic interactions, and favorable frontier molecular orbital
interactions. Likewise, the lowest-energy face-to-face orientation of
stauranthine with the guanine-cytosine base pair reveals favorable electrostatic
interactions as well as frontier molecular orbital interactions. Thus, not only
can quinoline alkaloids dock intercalatively into DNA, but the docked
orientations are also electronically favorable.
DOI: 10.1007/s00894-009-0501-6
PMID: 19424733 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/11230801
|
1. Biochem Pharmacol. 1999 May 15;57(10):1141-5. doi:
10.1016/s0006-2952(99)00018-0.
Topoisomerase II inhibition by aporphine alkaloids.
Woo SH(1), Sun NJ, Cassady JM, Snapka RM.
Author information:
(1)Department of Radiology, Division of Radiobiology; Department of Molecular
Virology, Immunology, and Human Genetics; The Ohio State University
Comprehensive Cancer Center, Columbus, Ohio 43210, USA.
The aporphine alkaloids (+)-dicentrine and (+)-bulbocapnine are non-planar
molecules lacking features normally associated with DNA binding by intercalation
or minor groove binding. Surprisingly, dicentrine showed significant activity as
a topoisomerase II (EC 5.99.1.3) inhibitor and also was active in a DNA
unwinding assay. The DNA unwinding suggests DNA intercalation, which could
explain the inhibition of topoisomerase II. Bulbocapnine, which differs from
dicentrine only by the presence of a hydroxyl group at position 11 and the
absence of a methoxyl group at position 9, was inactive in all assays. Molecular
modeling showed that dicentrine can attain a relatively planar conformation,
whereas bulbocapnine cannot, due to steric interaction between the 11-hydroxyl
group and an oxygen of the methylenedioxy ring. These observations suggest that
dicentrine is an "adaptive" DNA intercalator, which can bind DNA only by
adopting a somewhat strained planar conformation. The requirement of a
suboptimal conformation to achieve DNA binding appears to make dicentrine a
weaker topoisomerase II inhibitor than the very planar oxoaporphine alkaloid
liriodenine. These results suggest that it may be possible to modulate DNA
binding and biologic activity of drugs by modifications affecting their ability
to adopt planar conformations.
DOI: 10.1016/s0006-2952(99)00018-0
PMID: 11230801 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/10637356
|
1. Curr Med Chem. 2000 Jan;7(1):39-58. doi: 10.2174/0929867003375489.
Topoisomerase I poisons and suppressors as anticancer drugs.
Bailly C(1).
Author information:
(1)INSERM Unité 524 and Laboratoire de Pharmacologie Antitumorale du Centre
Oscar Lambret, IRCL, Place de Verdun, 59045 Lille, France.
bailly@lille.inserm.fr
Inhibitors of topoisomerase I constitute a novel family of antitumor agents. The
camptothecin derivatives topotecan and irinotecan represent new weapons in our
arsenal for battling human cancer. These two drugs act specifically at the level
of the topoisomerase I-DNA complex and stimulate DNA cleavage. This mechanism of
action is not restricted to the camptothecins. Numerous topoisomerase I poisons
including DNA minor groove binders such as Hoechst 33258 and DNA intercalators
such as benzophenanthridine alkaloids and indolocarbazole derivatives have been
discovered and developed. Another important group of topoisomerase I inhibitors
contains drugs which prevent or reverse topoisomerase I-DNA complex formation.
Many of these topoisomerase I suppressors are natural products (beta-lapachone,
diospyrin, topostatin, topostin, flavonoids) which are believed to interact
directly with the enzyme. This review is concerned with the different families
of topoisomerase I poisons and suppressors. Their origin, chemical nature and
mechanism of action are presented. The relationships between drug binding to DNA
and topoisomerase I inhibition are discussed.
DOI: 10.2174/0929867003375489
PMID: 10637356 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/18043127
|
1. Anticancer Drugs. 2008 Jan;19(1):23-36. doi: 10.1097/CAD.0b013e3282f00e17.
Synthesis and anticancer activities of 6-amino amonafide derivatives.
Norton JT(1), Witschi MA, Luong L, Kawamura A, Ghosh S, Stack MS, Sim E, Avram
MJ, Appella DH, Huang S.
Author information:
(1)Department of Cell and Molecular Biology, The Mary Beth Donnelley Clinical
Pharmacology Core Facility, Northwestern University Medical School, Chicago,
Illinois 60611, USA.
Amonafide is a DNA intercalator and topoisomerase II inhibitor in clinical
development for the treatment of neoplastic diseases. Amonafide contains a free
arylamine, which causes it to be metabolized in humans by N-acetyl transferase-2
(NAT2) into a toxic form. To eliminate the NAT2 acetylation of amonafide while
retaining the anticancer properties, we have synthesized nine derivatives that
are structurally similar to amonafide that should not be acetylated. Eight
derivatives have arylamines at the 6-position (vs. 5-position of amonafide) and
one derivative completely lacks the arylamine. The derivative with a free amine
in the 6-position and one with a substituted amine in the 6-position are not
acetylated, whereas amonafide is extensively acetylated as determined by an NAT2
assay. The biological activities of these compounds were evaluated to determine
whether they behaved similarly to amonafide in purified systems and in vitro. We
found that three compounds had similar cancer cell-selective growth inhibition
to amonafide, while retaining similar subcellular localization, DNA
intercalation and topoisomerase II inhibition activities. In addition, these
compounds were able to eliminate a marker of metastatic potential, the
perinucleolar compartment. These three compounds (named numonafides) might thus
allow for better patient management than those treated with amonafide; hence,
they should be developed further as potential clinical replacements for
amonafide or as novel anticancer drugs.
DOI: 10.1097/CAD.0b013e3282f00e17
PMID: 18043127 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/2695099
|
1. Anticancer Drug Des. 1989 Dec;4(4):241-63.
DNA-intercalating ligands as anti-cancer drugs: prospects for future design.
Denny WA(1).
Author information:
(1)Cancer Research Laboratory, University of Auckland School of Medicine, New
Zealand.
Interest in DNA-intercalating ligands as anti-cancer drugs has developed greatly
since the clinical success of doxorubicin. However, despite a great deal of
'rational design' of synthetic DNA-intercalators, only a few such compounds have
proved clinically useful. This review briefly surveys the history of
DNA-intercalators as clinically-used anti-cancer drugs, summarizes the known
structure-experimental activity relationships and modes of action, and concludes
that a factor in the slow progress is that much of the work on these compounds
has been carried out by chemists, who were generally more interested in
ligand/DNA interactions than drug development. Future development of the class
rests on a careful consideration of the biochemical reasons behind the common
limitations of the present drugs. The most important are: the inherent
resistance of non-cycling cells, the rapid development (even by cycling cells)
of resistance by the expression of both P-glycoprotein and altered topoisomerase
II, limitations on drug distribution to and transport into tumours, low
extravascular pH in tumours and the cardiotoxic side-effects of quinonoid
chromophores. These considerations provide a set of constraints on
physicochemical properties which must be considered in future design. However,
within these constraints, there are useful future avenues for the development of
DNA-intercalators as anti-cancer drugs. These include: (i) the production of
improved topoisomerase inhibitors (by consideration of drug/protein as well as
drug/DNA interactions); (ii) the development of reductively-activated
chromophores as hypoxia-selective agents; and (iii) the use of DNA-intercalators
of known DNA binding orientation as 'carriers' for the delivery of other
reactive functionality specifically (sequence-, regio- and site-specifically) to
DNA.
PMID: 2695099 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/8812219
|
1. Fundam Appl Toxicol. 1996 Jul;32(1):45-52. doi: 10.1006/faat.1996.0105.
Subchronic intravenous toxicity of the antineoplastic drug, amsacrine, in male
Wistar rats.
Pegg DG(1), Watkins JR, Graziano MJ, McKenna MJ.
Author information:
(1)Department of Pathology and Experimental Toxicology, Parke-Davis
Pharmaceutical Research Division, Warner-Lambert Company, Ann Arbor, Michigan
48105, USA.
Amsacrine, a DNA intercalator and topoisomerase II inhibitor, is efficacious as
an antileukemogenic agent. This study was conducted to assess the subchronic
toxicity of amsacrine in rats following a cyclic clinical dosing regimen and as
a range-finding experiment for a subsequent carcinogenicity bioassay. Groups of
30 male Wistar rats were administered drug intravenously at doses of 0, 0.25,
1.0, and 3.0 mg/kg daily for 5 days followed by 23 days without treatment. This
cycle of dosing and recovery was repeated six times to simulate human clinical
usage of the drug. Assessments of hematology, clinical chemistry, and gross and
microscopic pathology were conducted 3 and 21 days following completion of
dosing in the first, third, and sixth cycles. There were no deaths during the
study. Hair loss, diarrhea, tail injuries, chromodacryorrhea, and rhinorrhea
were observed primarily in animals administered 3 mg/kg. Hair loss and diarrhea
occurred during periods of dosing and generally resolved during the recovery
phase of each cycle. Both of these signs became progressively more severe during
the latter half of the study. Body weight loss and reduced food consumption also
occurred in the 3 mg/kg group during each week of dosing. At study termination,
mean body weight and food consumption of the 3 mg/kg group were significantly
less than those of controls by approximately 20 and 50%, respectively. Marked,
reversible leukopenia associated with reductions in both neutrophil and
lymphocyte counts occurred in cycles one and three in animals administered 1 and
3 mg/kg, respectively. Reversible neutropenia was also observed in the 3 mg/kg
group in cycle 6. Similar effects on platelet counts were seen in the 3 mg/kg
group in all three cycles analyzed. Absolute and relative testes weights of the
3 mg/kg group were significantly less than the vehicle controls at all time
points in the third and sixth cycles. Relative testes weights were also
decreased in the 1 mg/kg group in cycle 6. Reversible decreases in absolute
relative spleen weights occurred in all drug-treated groups in cycle 1 and for
the 3 mg/kg group in cycle 3. Lymphoid depletion (spleen, thymus, lymph node),
marked hypocellularity of bone marrow, segmental degeneration of seminiferous
tubules, and intestinal epithelial cell degeneration were observed at 3 mg/kg.
With the exception of testicular changes which remained evident at the end of
cycle 6, pathologic lesions were reversible during the 23-day recovery period of
each cycle. The results show that the subchronic toxicity of amsacrine is
consistent with a cytotoxic mechanism and that target organs are generally
tissues with the highest rates of cell turnover. The doses administered in this
study induced a range of effects which were minimal at 0.25 mg/kg and
dose-limiting at 3 mg/kg and therefore were considered appropriate for use in
the subsequent carcinogenicity bioassay.
DOI: 10.1006/faat.1996.0105
PMID: 8812219 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/8941714
|
1. FEBS Lett. 1996 Nov 11;397(1):61-4. doi: 10.1016/s0014-5793(96)01141-6.
Intracellular molecular interactions of antitumor drug amsacrine (m-AMSA) as
revealed by surface-enhanced Raman spectroscopy.
Chourpa I(1), Morjani H, Riou JF, Manfait M.
Author information:
(1)Laboratoire de Spectroscopie Biomoléculaire, UFR de Pharmacie, Université de
Reims, France.
Cytotoxicity of several classes of antitumor DNA intercalators is thought to
result from disturbance of DNA metabolism following trapping of the nuclear
enzyme DNA topoisomerase II as a covalent complex on DNA. Here, molecular
interactions of the potent antitumor drug amsacrine (m-AMSA), an inhibitor of
topoisomerase II, within living K562 cancer cells have been studied using
surface-enhanced Raman (SER) spectroscopy. The work is based on data of the
previously performed model SER experiments dealing with amsacrine/DNA,
drug/topoisomerase II and drug/DNA/topoisomerase II complexes in aqueous buffer
solutions. The SER data indicated two kinds of amsacrine interactions in the
model complexes with topoisomerase II alone or within ternary complex:
non-specific (via the acridine moiety) and specific to the enzyme conformation
(via the side chain of the drug). These two types of interactions have been both
revealed by the micro-SER spectra of amsacrine within living K562 cancer cells.
Our data suppose the specific interactions of amsacrine with topoisomerase II
via the side chain of the drug (particular feature of the drug/topoisomerase II
and ternary complexes) to be crucial for its inhibitory activity.
DOI: 10.1016/s0014-5793(96)01141-6
PMID: 8941714 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/16339144
|
1. J Biol Chem. 2006 Feb 10;281(6):3679-89. doi: 10.1074/jbc.M509630200. Epub
2005 Dec 8.
Differential regulation of cardiomyocyte survival and hypertrophy by MDM2, an E3
ubiquitin ligase.
Toth A(1), Nickson P, Qin LL, Erhardt P.
Author information:
(1)Boston Biomedical Research Institute, Watertown, Massachusetts 02472, USA.
MDM2 is an E3 ubiquitin ligase that regulates the proteasomal degradation and
activity of proteins involved in cell growth and apoptosis, including the tumor
suppressors p53 and retinoblastoma and the transcription factor E2F1. Although
the effect of several MDM2 targets on cardiomyocyte survival and hypertrophy has
already been investigated, the role of MDM2 in these processes has not yet been
established. We have, therefore, analyzed the effect of overexpression as well
as inhibition of MDM2 on cardiac ischemia/reperfusion injury and hypertrophy.
Here we show that isolated cardiac myocytes overexpressing MDM2 acquired
resistance to hypoxia/reoxygenation-induced cell death. Conversely, inactivation
of MDM2 by a peptide inhibitor resulted in elevated p53 levels and promoted
hypoxia/reoxygenation-induced apoptosis. Consistent with this, decreased
expression of MDM2 in a genetic mouse model was accompanied by reduced
functional recovery of the left ventricles determined with the Langendorff ex
vivo model of ischemia/reperfusion. In contrast to cell survival, cell
hypertrophy induced by the alpha-agonists phenylephrine or endothelin-1 was
inhibited by MDM2 overexpression. Collectively, our studies indicate that MDM2
promotes survival and attenuates hypertrophy of cardiac myocytes. This
differential regulation of cell growth and cell survival is unique, because most
other survival factors are prohypertrophic. MDM2, therefore, might be a
potential therapeutic target to down-regulate both cell death and pathologic
hypertrophy during remodeling upon cardiac infarction. In addition, our data
also suggest that cancer treatments with MDM2 inhibitors to reactivate p53 may
have adverse cardiac side effects by promoting cardiomyocyte death.
DOI: 10.1074/jbc.M509630200
PMID: 16339144 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/10434060
|
1. Biochim Biophys Acta. 1999 Aug 5;1428(2-3):406-14. doi:
10.1016/s0304-4165(99)00064-1.
Characterization of the genotoxicity of anthraquinones in mammalian cells.
Mueller SO(1), Stopper H.
Author information:
(1)Department of Toxicology, University of Würzburg, 97078, Würzburg, Germany.
mueller1@niehs.nih.gov
Naturally occurring 1,8-dihydroxyanthraquinones are under consideration as
possible carcinogens. Here we wanted to elucidate a possible mechanism of their
genotoxicity. All three tested anthraquinones, emodin, aloe-emodin, and
danthron, showed capabilities to inhibit the non-covalent binding of
bisbenzimide Hoechst 33342 to isolated DNA and in mouse lymphoma L5178Y cells
comparable to the topoisomerase II inhibitor and intercalator m-amsacrine. In a
cell-free decatenation assay, emodin exerted a stronger, danthron a similar and
aloe-emodin a weaker inhibition of topoisomerase II activity than m-amsacrine.
Analysis of the chromosomal extent of DNA damage induced by these anthraquinones
was performed in mouse lymphoma L5178Y cells. Anthraquinone-induced mutant cell
clones showed similar chromosomal lesions when compared to the topoisomerase II
inhibitors etoposide and m-amsacrine, but were different from mutants induced by
the DNA alkylator ethyl methanesulfonate. These data support the idea that
inhibition of the catalytic activity of topoisomerase II contributes to
anthraquinone-induced genotoxicity and mutagenicity.
DOI: 10.1016/s0304-4165(99)00064-1
PMID: 10434060 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/11077044
|
1. Biochem Pharmacol. 2000 Dec 1;60(11):1621-8. doi:
10.1016/s0006-2952(00)00472-x.
Catalytic inhibition of DNA topoisomerase II by N-benzyladriamycin (AD 288).
Lothstein L(1), Suttle DP, Roaten JB, Koseki Y, Israel M, Sweatman TW.
Author information:
(1)Department of Pharmacology, University of Tennessee Health Science Center,
38163, USA, Memphis, TN, USA. llothstein@utmem.edu
N-Benzyladriamycin (AD 288) is a highly lipophilic, semi-synthetic congener of
doxorubicin (DOX). Unlike DOX, which stimulates double-stranded DNA scission by
stabilizing topoisomerase II/DNA cleavable complexes, AD 288 is a catalytic
inhibitor of topoisomerase II, capable of preventing topoisomerase II activity
on DNA. The concentration of AD 288 required to inhibit the topoisomerase
II-catalyzed decatenation of linked networks of kinetoplast DNA was comparable
to that for DOX. However, AD 288 did not stabilize cleavable complex formation
or stimulate topoisomerase II-mediated DNA cleavage. In addition, AD 288
inhibited the formation of cleavable complexes by etoposide in a
concentration-dependent manner. Human CCRF-CEM cells and murine J774. 2 cells
exhibiting resistance against DOX, teniposide, or
3'-hydroxy-3'-deaminodoxorubicin through reduced topoisomerase II activity
remained sensitive to AD 288. These studies suggest that AD 288 inhibits
topoisomerase II activity by preventing the initial non-covalent binding of
topoisomerase II to DNA. Since AD 288 is a potent DNA intercalator, catalytic
inhibition is achieved by prohibiting access of the enzyme to DNA binding sites.
These results also demonstrate that specific substitutions on the aminosugar of
DOX can alter the mechanism of topoisomerase II inhibition.
DOI: 10.1016/s0006-2952(00)00472-x
PMID: 11077044 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/22304499
|
1. Biochemistry. 2012 Feb 28;51(8):1730-9. doi: 10.1021/bi201159b. Epub 2012 Feb
10.
Amsacrine as a topoisomerase II poison: importance of drug-DNA interactions.
Ketron AC(1), Denny WA, Graves DE, Osheroff N.
Author information:
(1)Department of Biochemistry, Vanderbilt University School of Medicine,
Nashville, Tennessee 37232-0146, United States.
Amsacrine (m-AMSA) is an anticancer agent that displays activity against
refractory acute leukemias as well as Hodgkin's and non-Hodgkin's lymphomas. The
drug is comprised of an intercalative acridine moiety coupled to a
4'-amino-methanesulfon-m-anisidide headgroup. m-AMSA is historically significant
in that it was the first drug demonstrated to function as a topoisomerase II
poison. Although m-AMSA was designed as a DNA binding agent, the ability to
intercalate does not appear to be the sole determinant of drug activity.
Therefore, to more fully analyze structure-function relationships and the role
of DNA binding in the action of m-AMSA, we analyzed a series of derivatives for
the ability to enhance DNA cleavage mediated by human topoisomerase IIα and
topoisomerase IIβ and to intercalate DNA. Results indicate that the 3'-methoxy
(m-AMSA) positively affects drug function, potentially by restricting the
rotation of the headgroup in a favorable orientation. Shifting the methoxy to
the 2'-position (o-AMSA), which abrogates drug function, appears to increase the
degree of rotational freedom of the headgroup and may impair interactions of the
1'-substituent or other portions of the headgroup within the ternary complex.
Finally, the nonintercalative m-AMSA headgroup enhanced enzyme-mediated DNA
cleavage when it was detached from the acridine moiety, albeit with 100-fold
lower affinity. Taken together, our results suggest that much of the activity
and specificity of m-AMSA as a topoisomerase II poison is embodied in the
headgroup, while DNA intercalation is used primarily to increase the affinity of
m-AMSA for the topoisomerase II-DNA cleavage complex.
DOI: 10.1021/bi201159b
PMCID: PMC3289736
PMID: 22304499 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/22659469
|
1. Am J Pathol. 2012 Aug;181(2):525-34. doi: 10.1016/j.ajpath.2012.04.014. Epub
2012 May 31.
Role of miR-132 in angiogenesis after ocular infection with herpes simplex
virus.
Mulik S(1), Xu J, Reddy PB, Rajasagi NK, Gimenez F, Sharma S, Lu PY, Rouse BT.
Author information:
(1)Department of Pathobiology, College of Veterinary Medicine, University of
Tennessee, Knoxville, Tennessee 37996, USA.
MicroRNAs (miRNAs) are small regulatory molecules that control diverse
biological processes that include angiogenesis. Herpes simplex virus (HSV)
causes a chronic immuno-inflammatory response in the eye that may result in
corneal neovascularization during blinding immunopathological lesion stromal
keratitis (SK). miR-132 is a highly conserved miRNA that is induced in
endothelial cells in response to growth factors, such as vascular endothelial
growth factor (VEGF). In this study, we show that miR-132 expression was
up-regulated (10- to 20-fold) after ocular infection with HSV, an event that
involved the production of both VEGF-A and IL-17. Consequently, blockade of
VEGF-A activity using soluble VEGF receptor 1 resulted in significantly lower
levels of corneal miR-132 after HSV infection. In addition, low levels of
corneal miR-132 were detected in IL-17 receptor knockout mice after HSV
infection. In vivo silencing of miR-132 by the provision of anti-miR-132
(antagomir-132) nanoparticles to HSV-infected mice led to reduced corneal
neovascularization and diminished SK lesions. The anti-angiogenic effect of
antagomir-132 was reflected by a reduction in angiogenic Ras activity in corneal
CD31-enriched cells (presumably blood vessel endothelial cells) during SK. To
our knowledge, this is one of the first reports of miRNA involvement in an
infectious ocular disease. Manipulating miRNA expression holds promise as a
therapeutic approach to control an ocular lesion that is an important cause of
human blindness.
Copyright © 2012 American Society for Investigative Pathology. Published by
Elsevier Inc. All rights reserved.
DOI: 10.1016/j.ajpath.2012.04.014
PMCID: PMC3409434
PMID: 22659469 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/2157558
|
1. Carcinogenesis. 1990 Apr;11(4):659-65. doi: 10.1093/carcin/11.4.659.
Involvement of DNA topoisomerase II in the selective resistance of a mammalian
cell mutant to DNA minor groove ligands: ligand-induced DNA-protein crosslinking
and responses to topoisomerase poisons.
Smith PJ(1), Bell SM, Dee A, Sykes H.
Author information:
(1)MRC Clinical Oncology and Radiotherapeutics Unit, MRC Centre, Cambridge, UK.
A mutant murine cell line has previously been reported to be resistant to the
AT-specific DNA minor groove ligand 2',5'-bi-1H-benzimidazole,
2',(4-ethoxyphenyl)-5-(4-methyl-1-piperazinyl), trichloride (Ho33342), due to an
enhanced capacity to remove ligand molecules from cellular DNA via a pathway
which can be blocked by DNA topoisomerase poisons. We have studied the
relationship between ligand resistance and DNA topoisomerase II activity. The
cross-sensitivity patterns of the mutant were examined for covalently
(anthramycin) and non-covalently (distamycin A) binding minor groove ligands,
and DNA intercalating [adriamycin, mitoxantrone and
4'-(9-acridinylamino)methanesulphon-m-anisidide (mAMSA)] and non-intercalating
(VP16-213) topoisomerase II poisons. The mutant was cross-resistant to
distamycin A alone. The mutant showed no abnormality in: (i) the in vitro
decatenation activity of topoisomerase II, (ii) VP16-213 or mAMSA induced
protein-DNA cross-linking activities in nuclear extracts, (iii) 'cleavable
complex' generation (or DNA strand scisson) in intact cells exposed to
topoisomerase poisons. Ho33342 and the topoisomerase II inhibitor novobiocin
were found to disrupt both the in vitro binding of nuclear extracted proteins,
from mutant and parental cells, to plasmid DNA and the formation of drug-induced
cleavable complexes in vitro. Unexpectedly, Ho33342 induced significant levels
of DNA-protein crosslinking in both parental and mutant cells. We conclude that:
(i) resistance of the mutant is limited to non-covalently binding minor groove
ligands, (ii) Ho33342 can block the trapping of DNA topoisomerase II by enzyme
poisons in vitro, (iii) Ho33342 can induce a novel form of DNA-protein
cross-link in intact cells, and (iv) the resistance of the mutant is not
dependent upon some abnormality in topoisomerase II function.
DOI: 10.1093/carcin/11.4.659
PMID: 2157558 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/8449832
|
1. Jpn J Cancer Res. 1993 Jan;84(1):93-8. doi:
10.1111/j.1349-7006.1993.tb02789.x.
Analysis of DNA fragmentation in human uterine cervix carcinoma HeLa S3 cells
treated with duocarmycins or other antitumor agents by pulse field gel
electrophoresis.
Okamoto A(1), Okabe M, Gomi K.
Author information:
(1)Pharmaceutical Research Laboratory, Kyowa Hakko Kogyo Co., Ltd.,
Shizuoka-ken.
Pulse field gel electrophoresis using a contour-clamped homogeneous electric
field was applied for the analysis of DNA-fragmenting activity of antitumor
agents towards human uterine cervix carcinoma HeLa S3 cells. Duocarmycins
(DUMs), novel antitumor antibiotics with ultrapotent cell growth-inhibitory
activities, caused DNA fragmentation at 10 times their IC50 values at 2 h
exposure. At 100 times their IC50 values, the size of the smallest fragments was
about 245 kilobase pairs (kbp). DUMA, DUMB1 and DUMB2 exhibited similar DNA
fragmentation patterns, suggesting similar action mechanisms. DNA fragmentation
was also detected in cells treated with radical producers, intercalators and
topoisomerase inhibitors. Two bands of about 1800 and 1500 kbp were commonly
detected in the cells treated with DUMs and these agents. In addition, fragments
of about 900 kbp were detected in the cells treated with a topoisomerase
inhibitor, 4'-(9-acridinylamino)methane-sulfon-m-anisidine, and fragments in the
broad size range between 700 and 245 kbp in the cells treated with radical
producers, bleomycin and neocarzinostatin. DUMs showed a characteristic DNA
fragmentation pattern, since both types of fragments induced by the
topoisomerase inhibitor and the radical producers were simultaneously detected,
suggesting a novel mode of interaction with DNA. DNA-crosslinking agents and
mitotic inhibitors did not induce DNA fragmentation under these conditions. The
pulse field gel electrophoresis is potentially useful for characterizing
DNA-cleaving activity of various antitumor agents at the cellular level.
DOI: 10.1111/j.1349-7006.1993.tb02789.x
PMCID: PMC5919028
PMID: 8449832 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/22315408
|
1. Proc Natl Acad Sci U S A. 2012 Feb 21;109(8):3125-30. doi:
10.1073/pnas.1113793109. Epub 2012 Feb 6.
MicroRNA-132 dysregulation in schizophrenia has implications for both
neurodevelopment and adult brain function.
Miller BH(1), Zeier Z, Xi L, Lanz TA, Deng S, Strathmann J, Willoughby D, Kenny
PJ, Elsworth JD, Lawrence MS, Roth RH, Edbauer D, Kleiman RJ, Wahlestedt C.
Author information:
(1)Department of Molecular Therapeutics, The Scripps Research Institute-Scripps
Florida, Jupiter, FL 33458, USA.
Schizophrenia is characterized by affective, cognitive, neuromorphological, and
molecular abnormalities that may have a neurodevelopmental origin. MicroRNAs
(miRNAs) are small noncoding RNA sequences critical to neurodevelopment and
adult neuronal processes by coordinating the activity of multiple genes within
biological networks. We examined the expression of 854 miRNAs in prefrontal
cortical tissue from 100 control, schizophrenic, and bipolar subjects. The
cyclic AMP-responsive element binding- and NMDA-regulated microRNA miR-132 was
significantly down-regulated in both the schizophrenic discovery cohort and a
second, independent set of schizophrenic subjects. Analysis of miR-132 target
gene expression in schizophrenia gene-expression microarrays identified 26 genes
up-regulated in schizophrenia subjects. Consistent with NMDA-mediated
hypofunction observed in schizophrenic subjects, administration of an NMDA
antagonist to adult mice results in miR-132 down-regulation in the prefrontal
cortex. Furthermore, miR-132 expression in the murine prefrontal cortex exhibits
significant developmental regulation and overlaps with critical
neurodevelopmental processes during adolescence. Adult prefrontal expression of
miR-132 can be down-regulated by pharmacologic inhibition of NMDA receptor
signaling during a brief postnatal period. Several key genes, including DNMT3A,
GATA2, and DPYSL3, are regulated by miR-132 and exhibited altered expression
either during normal neurodevelopment or in tissue from adult schizophrenic
subjects. Our data suggest miR-132 dysregulation and subsequent abnormal
expression of miR-132 target genes contribute to the neurodevelopmental and
neuromorphological pathologies present in schizophrenia.
DOI: 10.1073/pnas.1113793109
PMCID: PMC3286960
PMID: 22315408 [Indexed for MEDLINE]
Conflict of interest statement: Conflict of interest statement: R.J.K., T.A.L.,
S.D., and L.X. are employees of Pfizer Inc.; D.W. is the founder and owner of
Ocean Ridge Biotechnology Inc.; M.S.L. is President and CSO of RxGen Inc.; and
C.W. is a consultant for OPKO-CURNA.
|
http://www.ncbi.nlm.nih.gov/pubmed/16798938
|
1. Mol Pharmacol. 2006 Sep;70(3):1109-20. doi: 10.1124/mol.106.024372. Epub 2006
Jun 23.
Bisindenoisoquinoline
bis-1,3-{(5,6-dihydro-5,11-diketo-11H-indeno[1,2-c]isoquinoline)-6-propylamino}propane
bis(trifluoroacetate) (NSC 727357), a DNA intercalator and topoisomerase
inhibitor with antitumor activity.
Antony S(1), Agama KK, Miao ZH, Hollingshead M, Holbeck SL, Wright MH,
Varticovski L, Nagarajan M, Morrell A, Cushman M, Pommier Y.
Author information:
(1)Laboratory of Molecular Pharmacology, National Cancer Institute, 37 Convent
Dr., Bldg. 37, Room 5068, National Institutes of Health, Bethesda, MD
20892-4255, USA.
Indenoisoquinolines are topoisomerase (Top) I inhibitors developed to overcome
some of the limitations of camptothecins and expand their anticancer spectrum.
Bis-1,3-{(5,6-dihydro-5,11-diketo-11H-indeno[1,2-c]isoquinoline)-6-propylamino}-propane
bis(trifluoroacetate) (NSC 727357) is a novel dimeric indenoisoquinoline
derivative with potent antiproliferative activity in the NCI-60 cell line panel,
promising hollow fiber activity (score of 32) and activity against xenografts.
Submicromolar concentrations of the bisindenoisoquinoline NSC 727357 induce Top1
cleavage complexes at specific sites in biochemical assays. At higher
concentrations, inhibition of Top1 catalytic activity and DNA intercalation is
observed. NSC 727357 also induces a limited number of Top2-DNA cleavage
complexes. In contrast to the effect of other Top1 inhibitors, cells treated
with the bisindenoisoquinoline NSC 727357 show an arrest of cell cycle
progression in G(1) with no significant inhibition of DNA synthesis after a
short exposure to the drug. Moreover, unlike camptothecin and the
indenoisoquinoline MJ-III-65 (NSC 706744,
6-[3-(2-hydroxyethyl)aminopropyl]-5,6-dihydro-5,11-diketo-2,3-dimethoxy-(methylenedioxy)-11H-indeno[1,2-c]isoquinoline
hydrochloride), the cytotoxicity of bisindenoisoquinoline NSC 727357 is only
partially dependent on Top1 and p53, indicating that this drug has additional
targets besides Top1 and Top2.
DOI: 10.1124/mol.106.024372
PMID: 16798938 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/2537142
|
1. Cancer Res. 1989 Mar 1;49(5):1118-24.
Cellular consequences of overproduction of DNA topoisomerase II in an
ataxia-telangiectasia cell line.
Smith PJ(1), Makinson TA.
Author information:
(1)Medical Research Council Clinical Oncology and Radiotherapeutics Unit, M.R.C.
Centre, Cambridge, UK.
Abnormal expression of the nuclear-associated enzyme DNA topoisomerase II
(topoisomerase II) has been implicated in the in vitro phenotype of radiation
hypersensitive ataxia-telangiectasia (A-T) cells and in modifying sensitivity of
eukaryotic cells to topoisomerase II-inhibitor drugs [e.g., the DNA intercalator
amsacrine (mAMSA)]. To study such relationships, various SV40- and Epstein-Barr
Virus-transformed human cell lines derived from normal, A-T, or UV-sensitive
xeroderma pigmentosum donors have been assayed for their sensitivity to mAMSA
together with direct and indirect measurements of topoisomerase II expression.
We report on the identification of an SV40-transformed A-T fibroblast cell line
with abnormally high levels of topoisomerase II in nuclear protein extracts as
determined by immunoblotting, measurement of kinetoplast DNA decatenation
activity, and mAMSA-dependent DNA-protein cross-linking activity in a filter
binding assay. Using a flow cytometric assay for the analysis of reactivity of
nuclei with a polyclonal antitopoisomerase II antibody, overproduction was found
to occur in all phases of the cell cycle. High levels of topoisomerase II were
associated with hypersensitivity (5-10-fold) to mAMSA-induced cell cycle delay,
cell kill, and DNA strand breakage (assayed under protein-denaturing
conditions). Xeroderma pigmentosum (group A) cells demonstrated normal responses
to mAMSA. The results provide evidence that cellular potential for the
generation of topoisomerase II-dependent DNA damage is a major factor in
governing the sensitivity to mAMSA. Furthermore, underexpression of
topoisomerase II does not appear to be a primary factor in describing the in
vitro A-T phenotype. The findings also relate to how changes in chromatin
structure and function may either reflect or dictate the expression of
topoisomerase II in human cells.
PMID: 2537142 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/2845248
|
1. Mol Pharmacol. 1988 Oct;34(4):467-73.
DNA binding by epipodophyllotoxins and N-acyl anthracyclines: implications for
mechanism of topoisomerase II inhibition.
Chow KC(1), Macdonald TL, Ross WE.
Author information:
(1)Department of Pharmacology, University of Florida, Gainesville 32610.
Previous evidence suggests that epipodophyllotoxins, such as etoposide and
teniposide, and the N-acyl anthracycline AD41 inhibit topoisomerase II resealing
even though they apparently do not bind to DNA. Using experimental conditions
designed to detect limited numbers of DNA binding sites, we now report that both
epipodophyllotoxins and the N-acyl anthracyclines AD41 and AD32 bind to DNA.
Binding was greater to kinetoplast DNA than to pUC18 plasmid DNA. There was also
greater etoposide binding to single-stranded DNA than to double-stranded linear
or supercoiled DNA. Based on binding competition experiments, etoposide and
teniposide appear to have equal affinity for DNA, in spite of the fact that the
latter is more potent as a topoisomerase inhibitor. This suggests that the
difference in the drugs relates to protein interaction. There are 3- to 7-fold
more binding sites for AD41 than for AD32, depending on the DNA substrate
employed, and both drugs, unlike adriamycin, exhibit saturation of binding sites
over a concentration range of 0-50 microM when kinetoplast DNA is the substrate.
Evidence for DNA intercalation by AD41 is provided by the observation that the
drug introduces positive supercoils into covalently closed plasmid DNA. Based on
these data, a hypothesis is proposed that would provide a general mechanism
whereby intercalating agents and epipodophyllotoxins alter topoisomerase
function and presumably exert their antitumor effects.
PMID: 2845248 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/367540
|
1. Can J Biochem. 1978 Nov;56(11):1006-15. doi: 10.1139/o78-159.
Bis-intercalative binding to DNA of novel bis(10-methyl)acridinium chlorides and
its dependence on chain length of linker.
Lown JW, Gunn BC, Chang RY, Majumdar KC, Lee JS.
The synthesis of a series of novel bis(10-methyl)acridinium compounds (both
unsubstituted and the 6-chloro-2-methoxy substituted) linked by methylene
bridges of lengths from (CH2)4 to (CH2)12 and in one case by spermine is
described. Their ability to bind to duplex DNA was compared by their relative
inhibition of E. coli DNA polymerase catalyzed DNA synthesis. It was determined
that they function as DNA template inhibitors and do not affect the DNA
polymerase directly. Their ability to function as bis-intercalators was assessed
by a novel and convenient topoisomerase fluorescent assay. It was concluded that
whereas the (CH2)4-linked compounds act only as monofunctional intercalators
because of steric constraints the (CH2)6-, (CH2)8-, and (CH2)10-linked
substituted bisacridinium compounds, as well as the (CH2)10- and (CH2)12-
unsubstituted analogues, function as bis-intercalators with DNA.
DOI: 10.1139/o78-159
PMID: 367540 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/23560086
|
1. PLoS One. 2013;8(4):e60275. doi: 10.1371/journal.pone.0060275. Epub 2013 Apr
1.
CLL cells respond to B-Cell receptor stimulation with a microRNA/mRNA signature
associated with MYC activation and cell cycle progression.
Pede V(1), Rombout A, Vermeire J, Naessens E, Mestdagh P, Robberecht N,
Vanderstraeten H, Van Roy N, Vandesompele J, Speleman F, Philippé J, Verhasselt
B.
Author information:
(1)Department of Clinical Chemistry, Microbiology and Immunology; Faculty of
Medicine and Health Sciences, Ghent University, Ghent, Belgium.
Erratum in
PLoS One. 2014;9(1).
doi:10.1371/annotation/7ab67087-8bdd-458b-bb77-e03c166a87ca.
Chronic lymphocytic leukemia (CLL) is a disease with variable clinical outcome.
Several prognostic factors such as the immunoglobulin heavy chain variable genes
(IGHV) mutation status are linked to the B-cell receptor (BCR) complex,
supporting a role for triggering the BCR in vivo in the pathogenesis. The miRNA
profile upon stimulation and correlation with IGHV mutation status is however
unknown. To evaluate the transcriptional response of peripheral blood CLL cells
upon BCR stimulation in vitro, miRNA and mRNA expression was measured using
hybridization arrays and qPCR. We found both IGHV mutated and unmutated CLL
cells to respond with increased expression of MYC and other genes associated
with BCR activation, and a phenotype of cell cycle progression. Genome-wide
expression studies showed hsa-miR-132-3p/hsa-miR-212 miRNA cluster induction
associated with a set of downregulated genes, enriched for genes modulated by
BCR activation and amplified by Myc. We conclude that BCR triggering of CLL
cells induces a transcriptional response of genes associated with BCR
activation, enhanced cell cycle entry and progression and suggest that part of
the transcriptional profiles linked to IGHV mutation status observed in isolated
peripheral blood are not cell intrinsic but rather secondary to in vivo BCR
stimulation.
DOI: 10.1371/journal.pone.0060275
PMCID: PMC3613353
PMID: 23560086 [Indexed for MEDLINE]
Conflict of interest statement: Competing Interests: Bruno Verhasselt serves as
an academic editor of PLOS ONE. No other conflicts of interest are reported by
the authors. This does not alter the authors' adherence to all the PLOS ONE
policies on sharing data and materials.
|
http://www.ncbi.nlm.nih.gov/pubmed/2164630
|
1. Mol Pharmacol. 1990 Jul;38(1):38-45.
Effects of morpholinyl doxorubicins, doxorubicin, and actinomycin D on mammalian
DNA topoisomerases I and II.
Wassermann K(1), Markovits J, Jaxel C, Capranico G, Kohn KW, Pommier Y.
Author information:
(1)Division of Cancer Treatment, National Cancer Institute, National Institutes
of Health, Bethesda, Maryland 20892.
The effect of cyanomorpholinyldoxorubicin, morpholinyldoxorubicin, doxorubicin,
and Actinomycin D were studied on purified mouse leukemia (L1210) DNA
topoisomerases I and II. DNA unwinding and cross-linking were also studied. It
was found that 1) morpholinyldoxorubicin, cyanomorpholinyldoxorubicin, and
Actinomycin D (but not doxorubicin) stimulated DNA topoisomerase I-induced
cleavage at specific DNA sites; 2) only doxorubicin and Actinomycin D stimulated
DNA cleavage by DNA topoisomerase II; 3) at higher drug concentrations, DNA
intercalators suppressed enzyme-mediated DNA cleavage induced by DNA
topoisomerase I, as well as topoisomerase II; 4) only
cyanomorpholinyldoxorubicin produced DNA-DNA cross-links; no DNA unwinding could
be observed; and 5) DNA intercalation (unwinding) potency of
morpholinyldoxorubicin was about 2-fold less than that of doxorubicin. The data
indicate that some DNA intercalators are not only inhibitors of DNA
topoisomerase II but act also on DNA topoisomerase I. The stabilization of
cleavage intermediates by intercalators may have a common mechanism for DNA
topoisomerase I and DNA topoisomerase II.
PMID: 2164630 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/19609889
|
1. Clin Cardiol. 2009 Jul;32(7):380-5. doi: 10.1002/clc.20574.
Thyroid hormone and coronary artery disease: from clinical correlations to
prognostic implications.
Coceani M(1), Iervasi G, Pingitore A, Carpeggiani C, L'Abbate A.
Author information:
(1)Fondazione CNR-Regione Toscana Gabriele Monasterio, Pisa, Italy.
michecoc@ifc.cnr.it
BACKGROUND: Overt thyroid dysfunction, hypothyroidism in particular, may lead to
coronary artery disease (CAD). Whether more subtle anomalies of thyroid hormone
metabolism influence the progression of CAD remains a matter of speculation.
HYPOTHESIS: The occurrence of CAD and long-term prognosis in patients without a
history of either primary thyroid disease, myocardial infarction, or chronic
heart failure is related to serum levels of biologically active free
triiodothyronine (fT3).
METHODS: The cohort consisted of 1047 clinically and biochemically euthyroid
patients (median age 65.6 y and 69% male) who underwent coronary angiography in
our institute for suspected CAD.
RESULTS: Lower fT3 levels were predictive of both single-vessel (p = 0.012) and
multivessel (p = 0.009) CAD. Through a multivariate logistic regression
analysis, fT3 was still linked to the presence of CAD (hazard ratio [HR]: 0.48,
95% confidence interval [CI]: 0.34-0.68, p < 0.001). After a mean follow-up of
31 months, the survival rate was 95% and total mortality (log-rank 6.75, p =
0.009), as well as cardiac mortality (log-rank 8.26, p = 0.004), was greater
among patients with low T3 (fT3 < 2.10 pg/mL) syndrome. At subsequent
multivariate Cox regression analysis, the association between low T3 syndrome
and survival was maintained (total mortality HR: 1.80, 95% CI: 1.05-3.10, p =
0.034; cardiac mortality HR: 2.58, 95% CI: 1.13-5.93, p = 0.025).
CONCLUSIONS: In this selected population, fT3 levels were inversely correlated
to the presence of CAD and low T3 syndrome conferred an adverse prognosis, even
after adjusting for traditional coronary risk factors.
DOI: 10.1002/clc.20574
PMCID: PMC6653244
PMID: 19609889 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/22975492
|
1. Biol Pharm Bull. 2012;35(9):1432-9. doi: 10.1248/bpb.b110671.
Membrane perturbations induced by new analogs of neocryptolepine.
Jaromin A(1), Korycińska M, Piętka-Ottlik M, Musiał W, Peczyńska-Czoch W,
Kaczmarek Ł, Kozubek A.
Author information:
(1)Department of Lipids and Liposomes, Faculty of Biotechnology, University of
Wroclaw, Wroclaw, Poland. ajaromin@ibmb.uni.wroc.pl
Indoloquinoline alkaloids represent an important class of antimalarial,
antibacterial and antiviral compounds. Indolo[2,3-b]quinolines are a family of
DNA intercalators and inhibitors of topoisomerase II, synthetic analogs of
neocryptolepine, an alkaloid traditionally used in African folk medicine. These
cytotoxic substances are promising anticancer agents. Active representatives of
indolo[2,3-b]quinolines affect model and natural membranes. The distinct
structure and hydrophobicity of the compounds leads to marked differences in the
disturbing effects on membrane organization and function. Our results also
indicated a strong relationship between the presence of the chain and the Poct
of the molecule as well as the capacity for incorporation into
carboxyfluorescein-trapped liposomes in the 0.02-0.06 mM range. Moreover, a
correlation between binding to neutral dimyristoylphosphatidylcholine (DMPC) or
negative charged dimyristoylphosphatidylcholine:dimyristoylphosphatidylglycerol
(DMPC:DMPG, 9:1 w/w) liposomes, as well as to erythrocyte ghosts and pKa, was
also found. All the compounds cause hemolysis in isotonic conditions with
concentration causing 50% hemolysis (HC50) in the 0.12-0.88 mM range. The
concentration-dependent inhibitory effect of the tested agents on erythrocyte
ghosts' acetylcholinesterase activity was also studied.
DOI: 10.1248/bpb.b110671
PMID: 22975492 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/20133050
|
1. Cancer Lett. 2010 Jul 1;293(1):124-31. doi: 10.1016/j.canlet.2010.01.004. Epub
2010 Feb 4.
Expression profiling identifies epoxy anthraquinone derivative as a DNA
topoisomerase inhibitor.
Gheeya J(1), Johansson P, Chen QR, Dexheimer T, Metaferia B, Song YK, Wei JS, He
J, Pommier Y, Khan J.
Author information:
(1)Oncogenomics Section, Pediatric Oncology Branch, Advanced Technology Center,
National Cancer Institute, Gaithersburg, MD, USA.
To discover novel drugs for neuroblastoma treatment, we have previously screened
a panel of drugs and identified 30 active agents against neuroblastoma cells.
Here we performed microarray gene expression analysis to monitor the impact of
these agents on a neuroblastoma cell line and used the connectivity map (cMAP)
to explore putative mechanism of action of unknown drugs. We first compared the
expression profiles of 10 compounds shared in both our dataset and cMAP database
and observed the high connectivity scores for 7 of 10 matched drugs regardless
of the differences of cell lines utilized. The screen of cMAP for
uncharacterized drugs indicated the signature of Epoxy anthraquinone derivative
(EAD) matched the profiles of multiple known DNA targeted agents (topoisomerase
I/II inhibitors, DNA intercalators, and DNA alkylation agents) as predicted by
its structure. Similar result was obtained by querying against our internal
NB-cMAP (http://pob.abcc.ncifcrf.gov/cgi-bin/cMAP), a database containing the
profiles of 30 active drugs. These results suggest that Epoxy anthraquinone
derivative may inhibit neuroblastoma cells by targeting DNA replication
inhibition. Experimental data also demonstrate that Epoxy anthraquinone
derivative indeed induces DNA double-strand breaks through DNA alkylation and
inhibition of topoisomerase activity. Our study indicates that Epoxy
anthraquinone derivative may be a novel DNA topoisomerase inhibitor that can be
potentially used for treatment of neuroblastoma or other cancer patients.
DOI: 10.1016/j.canlet.2010.01.004
PMCID: PMC4698332
PMID: 20133050 [Indexed for MEDLINE]
Conflict of interest statement: 5. Conflict of interest The authors declare no
conflict of interest for this article.
|
http://www.ncbi.nlm.nih.gov/pubmed/19074430
|
1. J Biol Chem. 2009 Feb 13;284(7):4510-5. doi: 10.1074/jbc.M808495200. Epub 2008
Dec 12.
The role of cation binding in determining substrate selectivity of glutamate
transporters.
Huang S(1), Ryan RM, Vandenberg RJ.
Author information:
(1)Transporter Biology Group, Discipline of Pharmacology, School of Medical
Sciences, Bosch Institute, University of Sydney, Sydney, New South Wales 2006,
Australia.
Glutamate transport is coupled to the co-transport of 3Na(+) and 1H(+) and the
countertransport of 1 K(+). However, the mechanism of how this process occurs is
not well understood. The crystal structure of an archaeal homolog of the human
glutamate transporters, Glt(Ph), has provided the framework to begin to
understand the mechanism of transport. The glutamate transporter EAAT2 is
different from other subtypes in two respects. First, Li(+) cannot support
transport by EAAT2, whereas it can support transport by the other excitatory
amino acid transporters, and second, EAAT2 is sensitive to a wider range of
blockers than other subtypes. We have investigated the relationship between the
cation driving transport and whether the glutamate analogues,
l-anti-endo-3,4-methanopyrrolidine-dicarboxylic acid (MPDC) and
(2S,4R)-4-methylglutamate (4MG), are substrates or blockers of transport. We
have also investigated the molecular basis for these differences. EAAT2 has a
Ser residue at position 441 with hairpin loop 2, whereas the corresponding
residue in EAAT1 is a Gly residue. We demonstrate that if the transporter has a
Ser residue at this position, then 4MG and MPDC are poor substrates in Na(+),
and Li(+) cannot support transport of any substrate. Conversely, if the
transporter has a Gly residue at this position, then in Na(+) 4MG and MPDC are
substrates with efficacy comparable with glutamate, but in Li(+) 4MG and MPDC
are poor substrates relative to glutamate. This Ser/Gly residue is located
between the bound substrate and one of the cation binding sites, which provides
an explanation for the coupling of substrate and cation binding.
DOI: 10.1074/jbc.M808495200
PMID: 19074430 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/21303929
|
1. J Cell Sci. 2011 Mar 1;124(Pt 5):776-88. doi: 10.1242/jcs.072447. Epub 2011
Feb 8.
Translocation dynamics of sorting nexin 27 in activated T cells.
Rincón E(1), Sáez de Guinoa J, Gharbi SI, Sorzano CO, Carrasco YR, Mérida I.
Author information:
(1)Lipid signalling Laboratory, Centro Nacional de Biotecnología/CSIC, E-28049
Madrid, Spain.
Sorting nexin 27 (SNX27) belongs to the sorting nexin family of proteins, which
participate in vesicular and protein trafficking. Similarly to all sorting nexin
proteins, SNX27 has a functional PX domain that is important for endosome
binding, but it is the only sorting nexin with a PDZ domain. We identified SNX27
as a partner of diacylglycerol kinase ζ (DGKζ), a negative regulator of T cell
function that metabolises diacylglycerol to yield phosphatidic acid. SNX27
interacts with the DGKζ PDZ-binding motif in early/recycling endosomes in
resting T cells; however, the dynamics and mechanisms underlying SNX27
subcellular localisation during T cell activation are unknown. We demonstrate
that in T cells that encounter pulsed antigen-presenting cells, SNX27 in transit
on early/recycling endosomes polarise to the immunological synapse. A fraction
of SNX27 accumulates at the mature immunological synapse in a process that is
dependent on vesicular trafficking, binding of the PX domain to
phosphatidylinositol 3-phosphate and the presence of the PDZ region.
Downmodulation of expression of either SNX27 or DGKζ results in enhanced basal
and antigen-triggered ERK phosphorylation. These results identify SNX27 as a
PDZ-containing component of the T cell immunological synapse, and demonstrate a
role for this protein in the regulation of the Ras-ERK pathway, suggesting a
functional relationship between SNX27 and DGKζ.
DOI: 10.1242/jcs.072447
PMID: 21303929 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/20949564
|
1. Int J Cancer. 2011 Aug 1;129(3):680-90. doi: 10.1002/ijc.25715. Epub 2010 Nov
23.
Micro-RNA profiles in osteosarcoma as a predictive tool for ifosfamide response.
Gougelet A(1), Pissaloux D, Besse A, Perez J, Duc A, Dutour A, Blay JY, Alberti
L.
Author information:
(1)Unité INSERM U590 équipe Cytokines et Cancer, Centre Léon Bérard, 69373 Lyon
cedex 08, France. angeliquegougelet@gmail.com
Micro-RNAs (miRNA) are currently used as cancer biomarkers for hematological
cancers and solid tumors. Osteosarcoma is the first primary malignant bone
tumor, characterized by a complex genetic and resistance to conventional
treatments. For this latter property, the median survival has not been improved
since 1990 despite preoperative administration of chemotherapeutic agents. The
prediction of tumor response before chemotherapy treatment would constitute a
major progress for this pathology. We assessed in this study if miRNA profiling
could surpass the current limitations for osteosarcoma diagnosis. We measured
the miRNA expression in different osteosarcoma samples: (i) 27 osteosarcoma
paraffin-embedded tumors from patients, (ii) human osteosarcoma cell lines, and
(iii) tumors from a syngeneic rat osteosarcoma model, recapitulating human
osteosarcoma. miRNA profiles were determined using microfluidic cards performing
high-throughput TaqMan(®) -based PCR assays, called TaqMan(®) Low Density
Arrays. Osteosarcoma of rat and human origins showed a miRNA signature, which
could discriminate good from bad responders. In particular, we identified five
discriminating miRNAs (miR-92a, miR-99b, miR-132, miR-193a-5p and miR-422a) in
patient tumors, which could be easily transferable to diagnosis. These
discriminating miRNAs, as well as those identified in rat, targeted the TGFβ,
the Wnt and the MAP kinase pathways. These results indicate that our platform
constitutes a potent diagnostic tool to predict tumor sensitivity to a drug in
attempt to better adapt treatment to tumor biological specificities and also to
identify new potential therapeutic strategies.
Copyright © 2010 UICC.
DOI: 10.1002/ijc.25715
PMID: 20949564 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/11031254
|
1. J Biol Chem. 2001 Jan 5;276(1):576-82. doi: 10.1074/jbc.M003779200.
Amyotrophic lateral sclerosis-linked glutamate transporter mutant has impaired
glutamate clearance capacity.
Trotti D(1), Aoki M, Pasinelli P, Berger UV, Danbolt NC, Brown RH Jr, Hediger
MA.
Author information:
(1)Membrane Biology Program, Brigham and Women's Hospital, Harvard Medical
School, Boston, Massachusetts 02115, USA. dtrotti@rics.bwh.harvard.edu
We have investigated the functional impact of a naturally occurring mutation of
the human glutamate transporter GLT1 (EAAT2), which had been detected in a
patient with sporadic amyotrophic lateral sclerosis. The mutation involves a
substitution of the putative N-linked glycosylation site asparagine 206 by a
serine residue (N206S) and results in reduced glycosylation of the transporter
and decreased uptake activity. Electrophysiological analysis of N206S revealed a
pronounced reduction in transport rate compared with wild-type, but there was no
alteration in the apparent affinities for glutamate and sodium. In addition, no
change in the sensitivity for the specific transport inhibitor dihydrokainate
was observed. However, the decreased rate of transport was associated with a
reduction of the N206S transporter in the plasma membrane. Under ionic
conditions, which favor the reverse operation mode of the transporter, N206S
exhibited an increased reverse transport capacity. Furthermore, if coexpressed
in the same cell, N206S manifested a dominant negative effect on the wild-type
GLT1 activity, whereas it did not affect wild-type EAAC1. These findings provide
evidence for a role of the N-linked glycosylation in both cellular trafficking
and transport function. The resulting alteration in glutamate clearance capacity
likely contributes to excitotoxicity that participates in motor neuron
degeneration in amyotrophic lateral sclerosis.
DOI: 10.1074/jbc.M003779200
PMID: 11031254 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/15466885
|
1. J Cell Sci. 2004 Oct 15;117(Pt 22):5367-79. doi: 10.1242/jcs.01379. Epub 2004
Oct 5.
New sorting nexin (SNX27) and NHERF specifically interact with the 5-HT4a
receptor splice variant: roles in receptor targeting.
Joubert L(1), Hanson B, Barthet G, Sebben M, Claeysen S, Hong W, Marin P, Dumuis
A, Bockaert J.
Author information:
(1)Laboratoire de Génomique Fonctionnelle, CNRS UPR2580, CCIPE, 141 rue de la
Cardonille, 34094 Montpellier CEDEX 05, France.
The 5-hydroxytryptamine type 4 receptor (5-HT4R) is involved in learning,
feeding, respiratory control and gastrointestinal transit. This receptor is one
of the G-protein-coupled receptors for which alternative mRNA splicing generates
the most variants that differ in their C-terminal extremities. Some 5-HT4R
variants (a, e and f) express canonical PDZ ligands at their C-termini. Here, we
have examined whether some mouse 5-HT4R variants associate with specific sets of
proteins, using a proteomic approach based on peptide-affinity chromatography,
two-dimensional electrophoresis and mass spectrometry. We have identified ten
proteins that interact specifically with the 5-HT4(a)R and three that only
associate with the 5-HT4(e)R. Most of them are PDZ proteins. Among the proteins
that associated specifically with the 5-HT4(a)R variant, NHERF greatly modified
its subcellular localization. Moreover, NHERF recruited the 5-HT4(a)R to
microvilli, where it localized with activated ezrin, consistent with the role of
5-HT4(a)R in cytoskeleton remodelling. The 5-HT4(a)R also interacted with both
the constitutive and inducible (upon methamphetamine treatment) forms of the
recently cloned sorting nexin 27 (SNX27a and b, respectively). We found that
SNX27a redirected part of 5-HT4(a)R to early endosomes. The interaction of the
5-HT4R splice variants with distinct sets of PDZ proteins might specify their
cellular localization as well as their signal transduction properties.
DOI: 10.1242/jcs.01379
PMID: 15466885 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/22411990
|
1. J Biol Chem. 2012 Apr 27;287(18):15054-65. doi: 10.1074/jbc.M111.337931. Epub
2012 Mar 12.
Sorting nexin 27 interacts with multidrug resistance-associated protein 4 (MRP4)
and mediates internalization of MRP4.
Hayashi H(1), Naoi S, Nakagawa T, Nishikawa T, Fukuda H, Imajoh-Ohmi S, Kondo A,
Kubo K, Yabuki T, Hattori A, Hirouchi M, Sugiyama Y.
Author information:
(1)Laboratory of Molecular Pharmacokinetics, Department of Medical
Pharmaceutics, Graduate School of Pharmaceutical Sciences, University of Tokyo,
7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. hayapi@mol.f.u-tokyo.ac.jp
Multidrug resistance-associated protein 4 (MRP4/ABCC4) makes a vital
contribution to the bodily distribution of drugs and endogenous compounds
because of its cellular efflux abilities. However, little is known about the
mechanism regulating its cell surface expression. MRP4 has a PDZ-binding motif,
which is a potential sequence that modulates the membrane expression of MRP4 via
interaction with PDZ adaptor proteins. To investigate this possible
relationship, we performed GST pull-down assays and subsequent analysis with
matrix-assisted laser desorption/ionization-time of flight mass spectrometry.
This method identified sorting nexin 27 (SNX27) as the interacting PDZ adaptor
protein with a PDZ-binding motif of MRP4. Its interaction was confirmed by a
coimmunoprecipitation study using HEK293 cells. Knockdown of SNX27 by siRNA in
HEK293 cells raised MRP4 expression on the plasma membrane, increased the
extrusion of 6-[(14)C]mercaptopurine, an MRP4 substrate, and conferred
resistance against 6-[(14)C]mercaptopurine. Cell surface biotinylation studies
indicated that the inhibition of MRP4 internalization was responsible for these
results. Immunocytochemistry and cell surface biotinylation studies using COS-1
cells showed that SNX27 localized to both the early endosome and the plasma
membrane. These data suggest that SNX27 interacts with MRP4 near the plasma
membrane and promotes endocytosis of MRP4 and thereby negatively regulates its
cell surface expression and transport function.
DOI: 10.1074/jbc.M111.337931
PMCID: PMC3340259
PMID: 22411990 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/18690037
|
1. Channels (Austin). 2007 Sep-Oct;1(5):331-3. doi: 10.4161/chan.5191. Epub 2007
Oct 20.
Subunit-specific regulation of Kir3 channels by sorting nexin 27.
Nassirpour R(1), Slesinger PA.
Author information:
(1)The Salk Institute for Biological Studies, La Jolla, California 92037, USA.
G protein-gated inwardly rectifying potassium (Kir3) channels are involved in
regulating membrane excitability in the brain. Kir3 channels have been shown to
play a role in learning, analgesia and drug addiction. Little is known about the
cell surface regulation of Kir3 channels. Using a proteomics approach, we
recently discovered that sorting nexin 27 (SNX27) associates with a subset of
Kir3 channels. Sorting nexins have been implicated in trafficking of proteins
through endosomal compartments. The single PDZ domain of SNX27 binds directly to
the PDZ binding motif of Kir3 channels leading to their downregulation. Here, we
examined the functional effect of SNX27b expression on different subunit
combinations of the Kir3 family. Our results show that regulation of Kir3
channels by SNX27 depends critically on the combination of Kir3 subunits. This
type of subunit-specific regulation could be important for determining the
extent of Kir3 inhibition in normal as well as diseased states, such as drug
addiction.
DOI: 10.4161/chan.5191
PMID: 18690037 [Indexed for MEDLINE]
|
http://www.ncbi.nlm.nih.gov/pubmed/17577583
|
1. Biochem Biophys Res Commun. 2007 Aug 10;359(4):848-53. doi:
10.1016/j.bbrc.2007.05.162. Epub 2007 May 30.
Sorting nexin 27 interacts with the Cytohesin associated scaffolding protein
(CASP) in lymphocytes.
MacNeil AJ(1), Mansour M, Pohajdak B.
Author information:
(1)Department of Biology, Dalhousie University, Halifax, NS, Canada B3H 4J1.
CASP is a small cytokine-inducible protein, primarily expressed in hematopoetic
cells, which associates with members of the Cytohesin/ARNO family of guanine
nucleotide-exchange factors. Cytohesins activate ARFs, a group of GTPases
involved in vesicular initiation. Functionally, CASP is an adaptor protein
containing a PDZ domain, a coiled-coil, and a potential carboxy terminal
PDZ-binding motif that we sought to characterize here. Using GST pulldowns and
mass spectrometry we identified the novel interaction of CASP and sorting nexin
27 (SNX27). In lymphocytes, CASP's PDZ-binding motif interacts with the PDZ
domain of SNX27. This protein is a unique member of the sorting nexin family of
proteins, a group generally involved in the endocytic and intracellular sorting
machinery. Endogenous SNX27 and CASP co-localize at the early endosomal
compartment in lymphocytes and also in transfection studies. These results
suggest that endosomal SNX27 may recruit CASP to orchestrate intracellular
trafficking and/or signaling complexes.
DOI: 10.1016/j.bbrc.2007.05.162
PMID: 17577583 [Indexed for MEDLINE]
|
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.