Epitranscriptional Control of the Caspase-2—MDM2—p53 Axis: The Role of the m6A Writer in p53 Signaling.

The centrosome serves as the main microtubule-organizing center (MTOC) in animal cells, orchestrating essential processes such as spindle assembly and cell cycle progression. Centrosome amplification and cytokinesis failure are hallmarks of genomic instability, often observed in precancerous lesions and advanced malignancies. The p53 tumor suppressor pathway, acting through the Caspase-2–MDM2–p53 signaling axis, provides a crucial surveillance mechanism that detects centrosome aberrations and prevents the propagation of genomically unstable cells. Despite significant progress in understanding the proteolytic events driving this stress signalling response, the contribution of RNA-based regulatory layers has remained largely unexplored. This study identifies an unexpected role for N6-methyladenosine (m6A) RNA methylation as an essential post-transcriptional determinant of p53 activation in response to centrosome-derived stress. Using a genome-wide CRISPR/Cas9 screen coupled with a fluorescent reporter system, we uncovered all seven components of the m6A writer complex (METTL3, METTL14, WTAP, VIRMA, RBM15, ZC3H13, and CBLL1) as top-ranking hits required for proper activation of the Caspase-2–MDM2–p53 axis. Functional experiments demonstrated that METTL3 catalytic activity is indispensable for MDM2 processing and subsequent p53 stabilization. Pharmacological inhibition and catalytic-dead mutants confirmed that m6A deposition, rather than the scaffolding role of METTL3, underlies this regulatory effect. Epitranscriptomic profiling via m6A-Seq2 revealed that both p53 and MDM2 transcripts harbor prominent m6A peaks within their 3′UTRs. Interestingly, m6A modification in this context appears to act as a constitutive stabilizing layer rather than being dynamically remodeled during stress, fine-tuning transcript turnover and ensuring signaling fidelity. Inhibition of METTL3 activity reduced p53 mRNA stability and impaired MDM2 transcriptional induction, indicating that m6A supports both p53 expression and its downstream transcriptional feedback. Finally, depletion of YTHDF reader proteins phenocopied METTL3 loss, confirming that those specific proteins are key effectors, necessary for translating methylation signals into functional outcomes. These findings collectively establish an epitranscriptomic regulation that safeguards the fidelity of centrosome surveillance by integrating transcriptional, post-transcriptional, and proteolytic layers. Beyond elucidating this mechanism, the results also open new therapeutic perspectives. Since aberrant m6A methylation frequently occurs in human cancers, context-specific modulation of METTL3 activity may represent a potential strategy to tune p53-dependent tumor suppressive or gain-of-function responses in malignancies that specifically present mutant TP53.