Lady Davis Institute for Medical Research, Segal Cancer Centre, Jewish General Hospital, Montreal, QC, Canada.
Division of Experimental Medicine, McGill University, Montreal, QC, Canada.
EMBO J. 2018 Sep 14;37(18). doi: 10.15252/embj.2018100158. Epub 2018 Aug 28.
DNA double-strand breaks (DSBs) can be repaired by two major pathways: non-homologous end-joining (NHEJ) and homologous recombination (HR). DNA repair pathway choice is governed by the opposing activities of 53BP1, in complex with its effectors RIF1 and REV7, and BRCA1. However, it remains unknown how the 53BP1/RIF1/REV7 complex stimulates NHEJ and restricts HR to the S/G2 phases of the cell cycle. Using a mass spectrometry (MS)-based approach, we identify 11 high-confidence REV7 interactors and elucidate the role of SHLD2 (previously annotated as FAM35A and RINN2) as an effector of REV7 in the NHEJ pathway. FAM35A depletion impairs NHEJ-mediated DNA repair and compromises antibody diversification by class switch recombination (CSR) in B cells. FAM35A accumulates at DSBs in a 53BP1-, RIF1-, and REV7-dependent manner and antagonizes HR by limiting DNA end resection. In fact, FAM35A is part of a larger complex composed of REV7 and SHLD1 (previously annotated as C20orf196 and RINN3), which promotes NHEJ and limits HR Together, these results establish SHLD2 as a novel effector of REV7 in controlling the decision-making process during DSB repair.
DNA 双链断裂 (DSBs) 可以通过两种主要途径进行修复：非同源末端连接 (NHEJ) 和同源重组 (HR)。DNA 修复途径的选择受 53BP1 的拮抗活性控制，53BP1 与它的效应因子 RIF1 和 REV7 形成复合物，并与 BRCA1 相互作用。然而，目前尚不清楚 53BP1/RIF1/REV7 复合物如何刺激 NHEJ 并将 HR 限制在细胞周期的 S/G2 期。我们使用基于质谱 (MS) 的方法鉴定了 11 种高可信度的 REV7 相互作用蛋白，并阐明了 SHLD2（先前注释为 FAM35A 和 RINN2）作为 REV7 在 NHEJ 途径中的效应蛋白的作用。FAM35A 的缺失会损害 NHEJ 介导的 DNA 修复，并通过 B 细胞的类别转换重组 (CSR) 损害抗体多样性。FAM35A 在 DSB 处以 53BP1、RIF1 和 REV7 依赖的方式积累，并通过限制 DNA 末端切除来拮抗 HR。事实上，FAM35A 是由 REV7 和 SHLD1（先前注释为 C20orf196 和 RINN3）组成的更大复合物的一部分，该复合物促进 NHEJ 并限制 HR。总之，这些结果确立了 SHLD2 作为 REV7 控制 DSB 修复过程中决策的新效应因子。
