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PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
Moreover, our results align with prior studies comparing Tau phosphorylation in the LAN-5 cell line (endogenous levels of Tau) and a CHO cell line with stable Tau overexpression.
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
Those studies similarly demonstrated high phosphorylation levels at S202 and S404 under conditions of stable overexpression of Tau .
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
Furthermore, these observations provide a plausible explanation for variations in mitosis-specific phosphorylation of the PHF1 epitope across different cell lines, as these variations likely depend on the baseline phosphorylation levels during interphase .
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
Second, by avoiding the use of microtubule polymerizing or depolymerizing drugs to arrest cells in M phase, we minimized potential indirect effects of these agents.
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
This approach may explain some discrepancies between our findings and previously published data.
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
For instance, we did not observe p-S214 as a mitosis-specific phospho-epitope, as reported by Illenberger et al. , who used nocodazole-treated cells.
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
Similarly, we did not identify AT100 as a mitosis-specific phospho-epitope, contrary to the findings of Delobel et al. , who studied progesterone-induced maturation of Xenopus oocytes and Tau-stably transfected neuroblastoma cells.
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
Given the strong Tau-specific staining we achieved with both p-S214 and AT100 antibodies under the same immunocytochemistry conditions on specific Drosophila tissues , we can exclude antibody inefficiency as a contributing factor.
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
Finally, among the tested phospho-epitopes, we identified novel mitosis-specific phosphorylation sites, which are p-T205, p-T217 and p-S416.
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
Additionally, we confirmed previously described mitosis-specific phosphorylation sites, such as AT8 and p-S422 .
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
One important aspect of our study is the strategy used to validate in vitro findings in an in vivo system easily amenable to study cell division within an epithelial layer after three days of transient human Tau overexpression.
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
We chose Drosophila melanogaster because this model proved useful to study human Tau phosphorylation in the nervous tissue and because the molecular mechanisms governing cell division are evolutionarily conserved across animal species .
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
This model also enabled to validate the observed phospho-signature in non-cancerous cells.
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
In this system, the phospho-epitopes AT8, p-T217, and p-S422 displayed clear and strong staining that was almost exclusively localized to mitotic cells, confirming their mitotic specificity.
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
However, unlike the in vitro results, we observed distinct staining for p-T205 and p-S416 in non-mitotic cells.
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
These findings are consistent with the increase in staining, upon Tau overexpression, observed during interphase under in vitro conditions: the fold increases in staining intensity for AT8, p-T217, and p-S422 were modest (1.42-fold, 1.48-fold, and 1.65-fold, respectively) compared to the more substantial increases observed for p-T205 and p-S416 (5.34-fold and 3.39-fold, respectively).
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
This suggests that the slight increases in phosphorylation levels of p-T205 and p-S416 upon Tau overexpression during interphase in cell culture did not interfere with detecting additional phosphorylation at these sites during mitosis.
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
However, in the Drosophila wing disc in vivo, this distinction was less apparent.
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
Whether this observation applies broadly to other tissues warrants further investigation.
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
Our study focused on investigating the physiological phosphorylation of Tau during the cell cycle.
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
This work contributes to a broader effort to understand Tau phosphorylation under physiological conditions, such as during development or in response to hibernation and fluctuations in body temperature .
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
Here, we demonstrate that p-T217, a recently identified biomarker of early AD, is highly phosphorylated during mitosis, alongside the previously characterized AT8 and p-S422 phospho-epitopes.
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
These findings lend support to the longstanding hypothesis that cell-cycle reentry occurs in degenerating neurons during AD .
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
Critically, these results may also provide mechanistic insight into the emerging significance of p-T217 as an AD biomarker.
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
Alongside the AT8 epitope, p-T217 is detected in post-mortem brains of both asymptomatic individuals (Braak stages 0–III) and symptomatic AD patients , suggesting that these phosphorylations occur early in disease progression, potentially during preclinical or mild cognitive impairment stages.
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
Furthermore, recent studies highlight that plasma p-T217 exhibits superior diagnostic accuracy for AD compared to other established tau biomarkers .
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
Hence, specific kinases implicated in phosphorylating T217 as well as AT8 epitope and S422, their differential activity during mitosis—and their potential link to AD pathogenesis—warrants further investigation.
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
Recent reviews and the Hanger lab’s updated database (bit.ly/2JyZTbS) indicate that kinases known to phosphorylate both S202 and T205 for AT8 epitope, as well as T217 and S422 are GSK3, p38, ERK1/2, JNK1-3, and CK1/2.
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
Some of these kinases (e.g., ERK) have emerging roles in G2/M transition or mitotic organelle distribution or in mitotic checkpoint (e.g., CK1, GSK3) .
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
Previous work on recombinant Tau and Lan5 cell extracts showed that the mitotic cdk1/cdc2 kinase can phosphorylate Tau within a T212/T217 peptide .
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
To get further insight in the putative role of mitotic kinases like CDK1, Aurora, PLK and Nek , we used the GPS 6.0 software (https://gps.biocuckoo.cn/, accessed on 18 September 2025) to screen the 2N4R Tau sequence .
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
We found that S202, T205, T217, and S422 match CDK1 and Nek2 consensus motifs (Supplementary Table S3).
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
None of these aligned with Aurora or PLK consensus sequences.
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
Our work focused on the 4R isoform, which is more prone to aggregation , and overrepresented in insoluble fibrils in AD post-mortem tissues compared to the 3R isoform .
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
While all phospho-sites tested are present in the 3R isoform, future studies should examine this isoform to determine whether the mitotic phospho-signature is isoform-dependent.
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
A key unresolved question concerns the functional consequences of this mitotic phosphorylation pattern on Tau’s cellular roles.
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
The most immediate hypothesis is that it triggers Tau detachment from microtubules, a known mitotic event .
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
Given Tau’s established roles in promoting microtubule growth and inhibiting microtubule shrinkage , its release from microtubules could facilitate the dynamic microtubule remodeling essential for spindle assembly and mitotic progression.
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
However, whether this specific phospho-signature directly impairs Tau–microtubule binding remains to be experimentally validated.
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
Supporting this possibility, studies using a pseudo-phosphorylated TauE14 mutant—which mimics phosphorylation at all mitotic signature sites plus ten additional epitopes—demonstrate a dramatically reduced microtubule affinity .
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
Emerging evidence further suggests that modulating Tau phosphorylation in cancer cells can alter cell cycle progression .
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
Moving forward, it will be critical to dissect Tau’s functional contributions to mitotic microtubule dynamics and clarify how its phosphorylation state regulates these processes.
PMC12562719
Phospho-Tau Signature During Mitosis: AT8, p-T217 and p-S422 as Key Phospho-Epitopes
Such work may bridge critical gaps in our understanding of Tau’s dual roles in normal cell division and neurodegenerative pathology.
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
MYCN and c-MYC are critical driver oncogenes in several childhood cancers, including neuroblastoma.
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
Currently, the clinical development of MYC inhibitors has been hindered by the intrinsically disordered structure of MYC proteins, which lack well-defined ligand-binding pockets.
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
Proliferation-associated protein 2G4 (PA2G4) directly binds to and stabilizes MYCN protein, leading to markedly increased MYCN levels in neuroblastoma cells.
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
Here, we demonstrate that PA2G4 is essential for MYCN-driven tumor growth in neuroblastoma in vivo.
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
Moreover, PA2G4 elevates c-MYC protein levels in neuroblastoma cells by inhibiting its ubiquitin-mediated degradation.
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
In turn, c-MYC upregulates the transcription and protein expression of PA2G4, creating an oncogenic feed-forward expression loop.
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
A small molecule PA2G4 inhibitor, WS6, directly disrupts the PA2G4-c-MYC protein–protein interaction, resulting in decreased levels of both PA2G4 and c-MYC.
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
WS6 exhibited selective cytotoxicity in c-MYC-overexpressing cell lines.
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
Together, these findings identify PA2G4 as a shared cofactor for both the c-MYC and MYCN oncoproteins and highlight its interaction with MYC family oncoproteins as a promising therapeutic vulnerability in MYC-driven cancers.
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
The MYC oncogene is deregulated in more than 50% of human cancers, including both adult and pediatric malignancies .
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
The MYC family of oncogenes (c-MYC, MYCN, and L-MYC) encode transcription factors, expressed ubiquitously across cells .
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
These transient “super-transcription factors” regulate over 15% of the human genome, controlling crucial cellular processes such as metabolism , proliferation , differentiation , and apoptosis .
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
Despite their critical role in oncogenesis, direct therapeutic targeting of MYC proteins has proven difficult, as it is an intrinsically disordered protein without a specific active site and with no hydrophobic pockets .
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
As a transcription factor, MYC is located in the nucleus, making it inaccessible to monoclonal antibody therapies .
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
Consequently, MYC has been labeled “undruggable,” and research has primarily focused on indirect approaches for targeting its function .
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
In recent years, extensive efforts have been made to inhibit MYC at various stages of its biogenesis and activity .
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
These include targeting MYC gene transcription, MYC mRNA translation, MYC/Max interaction , MYC protein stability , and MYC downstream pathways .
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
We previously identified a novel MYCN binding protein known as proliferation-associated protein 2G4 (PA2G4), which stabilizes MYCN and prevents its degradation .
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
One mechanism by which PA2G4 can cause MYC stabilization is by sequestering Fbxw7, a component of the ubiquitin–proteasome pathway , in the cytoplasm.
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
In neuroblastoma cells, PA2G4 and MYCN act together in a forward feedback loop, driving continued tumorigenesis .
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
High PA2G4 expression independently predicts poor patient survival.
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
Targeting PA2G4/MYCN binding by WS6, a small molecule inhibitor, leads to reduced levels of both proteins and suppresses neuroblastoma tumorigenicity in vitro and in vivo .
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
While the PA2G4-MYCN interaction in neuroblastoma has been well characterized , little is known about its potential role in regulating c-MYC.
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
Notably, in high-risk neuroblastoma cases lacking MYCN amplification, c-MYC overexpression can serve as a functional driver, conferring similarly poor clinical outcomes .
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
MYCN and c-MYC share significant structural and functional homology , with both genes composed of three exons interrupted by two introns and showing 84% amino acid identity in common regions.
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
In mouse models, MYCN can compensate for the normal functions of c-MYC, supporting survival, development, and reproduction in the absence of c-MYC .
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
This functional redundancy suggests a conserved oncogenic role for PA2G4 across MYC family members and raises the possibility that PA2G4 may also contribute to tumorigenesis through stabilization of c-MYC in c-MYC-driven malignancies.
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
In this study, we reveal PA2G4 as a critical cofactor for both MYCN and c-MYC in neuroblastoma.
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
We demonstrate that PA2G4 promotes MYCN-driven tumor growth in vivo and stabilizes c-MYC protein by preventing its proteasomal degradation.
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
Furthermore, we identify a feed-forward loop wherein c-MYC transcriptionally upregulates PA2G4 expression.
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
Targeting this oncogenic axis with the small-molecule inhibitor WS6 disrupts the PA2G4–c-MYC interaction, reduces oncoprotein levels, and selectively impairs the viability of c-MYC-overexpressing cells.
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
These findings establish PA2G4 as a shared vulnerability in MYC-driven neuroblastoma and a promising therapeutic target.
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
Neuroblastoma cell lines (SH-SY5Y, SK-N-AS) and two normal lung fibroblast cell lines (MRC-5 and WI-38) were obtained from the American Type Culture Collection (ATCC).
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
SH-SY5Y and SK-N-AS cells were maintained in Dulbecco’s modified Eagle’s medium (DMEM) (Invitrogen Life Technologies, Carlsbad, CA, USA) with 10% fetal Bovine serum (FBS).
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
MRC-5 and WI-38 were cultured in Alpha-MEM media (Invitrogen, Life Technologies) with 10% FBS.
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
Human B-Acute Lymphoblastic Leukemia (B-ALL) cell lines; KOPN-8, SEM-K2, and human Burkitt’s Lymphoma (BL) cell lines; and Raji and P493-6 were maintained in Roswell Park Memorial Institute (RPMI) 1640 medium (Life Technologies) supplemented with 10% FBS.
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
Murine B-cell ALL cell lines WEHI-47 and WEHI-116, derived from the Eµ-Myc mouse model (Walter and Eliza Hall Institute of Medical Research, Parkville, Australia), were maintained in DMEM supplemented with 10% FBS, 100 μM L-aspafbragine, and 55 μM β-metacaptoethanol.
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
Medulloblastoma cell line UW-288 was obtained from Dr Nick Gottardo (Telethon Kids Institute, Nedlands, Australia) and maintained in DMEM supplemented with 10% FBS.
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
All cell lines used were authenticated by Cell Bank Australia (Westmead, Australia), free from mycoplasma, and cultured at 37 °C and 5% CO2 in a humidifier incubator.
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
The P493-6 cell line was established from the stable transfection of EBNA2-conditional EREB2-5 cells (B-cells), with a c-MYC expression construct (pmyc-tet), and was provided by Stefania Purgato, Dipartimento di Farmacia e Biotecnologie (FABIT, Bologna, Italy).
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
To suppress the expression of c-MYC in P493-6 cells, 1 µg/mL doxycycline (Life Technologies) was added to cells growing in RPMI medium.
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
P493-6 cells treated with doxycycline to repress c-MYC are referred to as P493-6 +Dox, and untreated cells are referred to as P493-6 -Dox.
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
Cell viability was assessed using resazurin.
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
The reagent was prepared in phosphate-buffered saline (PBS) and contained 75 mg resazurin, 12.5 mg methylene blue, 164.5 mg potassium hexacyanoferrate (III), and 211 mg potassium hexacyanoferrate (II) trihydrate in 500 mL of PBS.
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
After 6 h incubation with resazurin, the change in fluorescence was measured by Victor 3 multilabel Plate Reader (Perkin Elmer, Shelton, CT, USA) at an excitation wavelength of 560 nm and an emission wavelength of 590 nm.
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
Protein was extracted from cell pellets using RIPA buffer (Sigma-Aldrich, Burlington, MA, USA) with 10% protease inhibitor (Sigma-Aldrich).
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
Quantification of proteins was conducted using the Pierce BCA protein assay kit (Thermo Scientific, Waltham, MA, USA) according to the manufacturer’s instructions.
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
A total of 30–50 μg protein samples were loaded onto Criterion TGX 10% precast gel (Bio-Rad, Gladesville, Australia) and transferred to a nitrocellulose membrane (Bio-Rad).
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
The membrane was blocked in 5% skim milk in Tris-buffered saline with Tween-20 (20 mM Tris-HCl (pH 7.6), 137 mM NaCl, and 0.1% Tween-20 for an hour before incubation at 4 °C overnight with the following primary antibodies: rabbit anti-cMYC (1:1000, Cell Signaling Technologies, Beverly, MA, USA), rabbit anti-PA2G4 (1:2000, Atlas Antibodies, Stockholm, Sweden, Cat# HPA016484), mouse anti-Vinculin (1:2000, Sigma-Aldrich, Cat# V9131), mouse anti-GAPDH (1:2000, Santa Cruz Biotechnology, Santa Cruz, CA, USA, Cat# sc-365062), and rabbit anti-β-actin (1:5000, Sigma, Cat# SAB2100037).
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
Anti-mouse or anti-rabbit horseradish peroxidase secondary antibodies (1:5000, Life Technologies, Cat# 31430, 31460) were added and incubated for 2 h at room temperature.
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
Immunoblots were visualized by Clarity ECL reagent (Bio-Rad) and ChemiDoc MP Imaging System (Bio-Rad).
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
Quantification of protein expression was measured by Image Lab software v6.1 (Bio-Rad) and normalized to loading control.
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
For siRNA-mediated knockdown, 40 nM of Qiagen (Millennium Science Australia, Victoria, Australia) custom PA2G4 duplex oligos (PA2G4 siRNA#1: 5′-GAGCAACAGGAGCAAACTATT-3′, PA2G4 siRNA#2: 5′-ACTGAGCCTGTGTGAGAAATT-3′, or cMYC siRNA#5: 5′-ATGCTATTGCTGTTCTAATTA-3′, cMYC siRNA #7 5′-GATGAGGAAGAAATCGATG-3′) were transfected with lipofectamine 2000 (Life Technologies) according to the manufacturer’s instructions.
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
Dharmacon on-target plus control siRNA (Cat# D-001810-10-20) was used as siControl.
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
Cells were transfected between 24, 48, 72, and 96 h, depending on the experimental requirements.
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
All experimental procedures involving mice were approved by the University of New South Wales Animal Care and Ethics Committee according to the Animal Research Act, 1985 (Australia), and the Australian Code of Practice for Care and Use of Animals for Scientific Purposes 2015 (Approval number: 20/68B, Approval date: April 2020).
PMC12468391
PA2G4 Functions as a Cofactor for MYC Family Oncoproteins in MYC-Driven Malignancies
The TH-MYCN transgenic mouse model of neuroblastoma used has been previously described .