Arginine methylation of BRD4 by PRMT2/4 governs transcription and DNA repair

BRD4 functions as an epigenetic reader and plays a crucial role in regulating transcription and genome stability. Dysregulation of BRD4 is frequently observed in various human cancers. However, the molecular details of BRD4 regulation remain largely unknown. Here, we report that PRMT2- and PRMT4-mediated arginine methylation is pivotal for BRD4-dependent transcription, DNA repair, and tumor growth. Specifically, PRMT2/4 interact with and methylates BRD4 at R179, R181, and R183. This arginine methylation selectively controls a transcriptional program by promoting BRD4 enrichment at the hyper-acetylated chromatin regions. Moreover, BRD4 arginine methylation is induced by DNA damage and thereby promotes its binding to chromatin for DNA repair. Deficiency in BRD4 arginine methylation significantly suppresses tumor growth and sensitizes cells to BET inhibitors and DNA damaging agents. Therefore, our findings reveal an arginine methylation-dependent regulatory mechanism of BRD4 function and highlight targeting PRMT2/4 for better anti-tumor effect of BET inhibitors and DNA damaging agents. Overall design: To identify the co-regulation genes of BRD4 and PRMT2/4, we depleted BRD4 or PRMT2/4 by shRNA in MCF7 cells and then performed RNA-seq.