PDF(Pubmed)
Abstract：
G0-G1 phase alternative end joining (A-EJ) is a recently defined mutagenic pathway characterized by resected deletion and translocation joints that are predominantly direct and are distinguished from A-EJ in cycling cells that rely much more on microhomology-mediated end joining (MMEJ). Using chemical and genetic approaches, we systematically evaluate potential A-EJ factors and DNA damage response (DDR) genes to support this mechanism by mapping the repair fates of RAG1/2-initiated double-strand breaks in the context of Igκ locus V-J recombination and chromosome translocation. Our findings highlight a polymerase theta-independent Parp1-XRCC1/LigIII axis as central A-EJ components, supported by 53BP1 in the context of an Ataxia-telangiectasia mutated (ATM)-activated DDR. Mechanistically, we demonstrate varied changes in short-range resection, MMEJ, and translocation, imposed by compromising specific DDR activities, which include polymerase alpha, Ataxia-telangiectasia and Rad3-related (ATR), DNA2, and Mre11. This study advances our understanding of DNA damage repair within the 53BP1 regulatory domain and the RAG1/2 postcleavage complex.
摘要：
G0-G1期交替末端连接（A-EJ）是最近定义的诱变途径，其特征是切除的缺失和易位接头主要是直接的，并且在循环细胞中与A-EJ区分开来，后者更多地依赖于微同源介导的末端连接（MMEJ）。使用化学和遗传方法，我们通过在Igκ基因座V-J重组和染色体易位的背景下绘制RAG1/2启动的双链断裂的修复命运,系统地评估了潜在的A-EJ因子和DNA损伤应答(DDR)基因以支持这一机制.我们的发现强调了不依赖聚合酶θ的Parp1-XRCC1/LigIII轴作为中心A-EJ成分，在共济失调-毛细血管扩张症突变（ATM）激活的DDR的背景下，由53BP1支持。机械上,我们展示了短程切除的各种变化，MMEJ,和易位，通过损害具体的解除武装、复员和重返社会活动而强加的，其中包括聚合酶α，共济失调-毛细血管扩张和Rad3相关（ATR），DNA2和Mre11。这项研究促进了我们对53BP1调节域和RAG1/2裂解后复合物内DNA损伤修复的理解。
