Department of Immunology, University of Toronto, Toronto, Ontario, Canada.
Department of Immunology, University of Toronto, Toronto, Ontario, Canada
Mol Cell Biol. 2019 Apr 2;39(8). doi: 10.1128/MCB.00488-18. Print 2019 Apr 15.
Histone posttranslational modifications play fundamental roles in the regulation of double-stranded DNA break (DSB) repair. RNF20/RNF40-mediated monoubiquitination of histone H2B on lysine 120 (H2Bub) has been suggested as a potential mediator of DSB repair, although the nature and function of this posttranslational modification remain enigmatic. In this report, we demonstrate that RNF20 and RNF40 are required for DSB repair leading to homologous recombination (HR) and class switch recombination, a process driven by nonhomologous end joining (NHEJ), in mouse B cells. These findings suggest a role for RNF20 and RNF40 in DSB repair proximal to NHEJ/HR pathway choice and likely in the signaling of DSBs. We found that DSBs led to a global increase in H2Bub but not the transcription-associated posttranslational modifications H3K4me3 and H3K79me2. We also found that H2AX phosphorylation was dispensable for H2Bub and that ATM and ATR jointly regulate ionizing radiation (IR)-induced H2Bub. Together, our results suggest that RNF20, RNF40, and H2Bub may represent a novel pathway for DSB sensing and repair.
组蛋白翻译后修饰在调节双链 DNA 断裂 (DSB) 修复中起着至关重要的作用。RNF20/RNF40 介导的组蛋白 H2B 赖氨酸 120 上的单泛素化 (H2Bub) 被认为是 DSB 修复的潜在介质，尽管这种翻译后修饰的性质和功能仍然是个谜。在本报告中，我们证明 RNF20 和 RNF40 是小鼠 B 细胞中非同源末端连接 (NHEJ) 驱动的双链断裂 (DSB) 修复导致同源重组 (HR) 和类别转换重组所必需的。这些发现表明 RNF20 和 RNF40 在 NHEJ/HR 途径选择和 DSB 信号转导附近的 DSB 修复中起作用。我们发现 DSB 导致 H2Bub 的全局增加，但不导致与转录相关的翻译后修饰 H3K4me3 和 H3K79me2。我们还发现 H2AX 磷酸化对于 H2Bub 是可有可无的，并且 ATM 和 ATR 共同调节电离辐射 (IR) 诱导的 H2Bub。总之，我们的结果表明 RNF20、RNF40 和 H2Bub 可能代表 DSB 感应和修复的新途径。
