Double-strand breaks (DSBs) are the most deleterious DNA lesions, which, if left unrepaired, may lead to genome instability or cell death. Here, we report that, in response to DSBs, the RNA methyltransferase METTL3 is activated by ATM-mediated phosphorylation at S43. Phosphorylated METTL3 is then localized to DNA damage sites, where it methylates the N6 position of adenosine (m6A) in DNA damage-associated RNAs, which recruits the m6A reader protein YTHDC1 for protection. In this way, the METTL3-m6A-YTHDC1 axis modulates accumulation of DNA-RNA hybrids at DSBs sites, which then recruit RAD51 and BRCA1 for homologous recombination (HR)-mediated repair. METTL3-deficient cells display defective HR, accumulation of unrepaired DSBs, and genome instability. Accordingly, depletion of METTL3 significantly enhances the sensitivity of cancer cells and murine xenografts to DNA damage-based therapy. These findings uncover the function of METTL3 and YTHDC1 in HR-mediated DSB repair, which may have implications for cancer therapy.

双链断裂 (DSB) 是最有害的 DNA 损伤，如果不加以修复，可能会导致基因组不稳定或细胞死亡。在这里，我们报告说，响应于 DSB，RNA 甲基转移酶 METTL3 被 ATM 介导的 S43 磷酸化激活。然后磷酸化的 METTL3 被定位到 DNA 损伤位点，在那里它甲基化 DNA 损伤相关 RNA 中腺苷 (m6A) 的 N6 位置，从而招募 m6A 阅读器蛋白 YTHDC1 进行保护。通过这种方式，METTL3-m6A-YTHDC1 轴调节 DNA-RNA 杂合体在 DSB 位点的积累，然后募集 RAD51 和 BRCA1 进行同源重组 (HR) 介导的修复。METTL3 缺陷细胞显示 HR 缺陷、未修复 DSB 的积累和基因组不稳定性。因此，METTL3 的消耗显着增强了癌细胞和小鼠异种移植物对基于 DNA 损伤的治疗的敏感性。这些发现揭示了 METTL3 和 YTHDC1 在 HR 介导的 DSB 修复中的功能，这可能对癌症治疗有影响。