YTHDC1 m6A-dependent and m6A-independent functions converge to preserve DNA damage response.

Cells have evolved a robust and highly regulated DNA damage response to preserve their genomic integrity. Although increasing evidence highlights the relevance of RNA regulation, our understanding of its impact on a fully efficient DNA damage response remains limited. Here, through a targeted CRISPR-knockout screen, we identified RNA binding proteins and modifiers that participate in mediating the p53 response. Among the top hits, m6A reader YTHDC1 was identified as a master regulator of p53 expression. YTHDC1 binds to the transcription start sites of TP53 and other genes involved in DNA damage response, promoting their transcriptional elongation. YTHDC1 deficiency leads to reduced TP53 expression, and also retention of introns leading to aberrant protein production of key DNA damage factors. While intron retention is dependent on m6A, YTHDC1 favors TP53 transcriptional pause-release independently of m6A. Depletion of YTHDC1 causes genomic instability and aberrant cancer cell proliferation mediated by genes regulated by YTHDC1. Our results uncover YTHDC1 as an orchestrator of the DNA damage response through distinct mechanisms of co-transcriptional mRNA regulation.