Clinical and Translational Research Center of Shanghai First Maternity & Infant Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Sciences and Technology, Tongji University, Shanghai 200092, China.
Department of Biology, University of Rochester, Rochester, NY 14627, USA.
Nucleic Acids Res. 2019 Sep 19;47(16):8563-8580. doi: 10.1093/nar/gkz592.
Creating access to DNA double-strand break (DSB) sites in the chromatin context is an essential step during the repair process, but much remains to be determined about its regulatory mechanisms. Here, using a novel reporter cassette for simultaneous detection of homologous recombination (HR) and nonhomologous end joining (NHEJ) at the same chromosomal site, we report that the efficiency of HR but not NHEJ negatively correlates with nucleosome density. We demonstrate that PARP1 is required for HR by modulating nucleosome density at damage sites. Mechanistic studies indicate that the ATPase domain of BRG1 and the ZnF domain of SIRT1 interact with poly-ADP ribose (PAR) in response to DNA damage, and are responsible for bringing the two factors to broken DNA ends. At DNA damage sites, BRG1 and SIRT1 physically interact, whereupon SIRT1 deacetylates BRG1 at lysine residues 1029 and 1033, stimulating its ATPase activity to remodel chromatin and promote HR.
在修复过程中，创建 DNA 双链断裂 (DSB) 位点进入染色质环境是一个必要的步骤，但关于其调控机制仍有许多需要确定。在这里，我们使用一种新的报告基因盒，用于同时检测同一染色体位点的同源重组 (HR) 和非同源末端连接 (NHEJ)，我们报告说 HR 的效率而非 NHEJ 与核小体密度呈负相关。我们证明 PARP1 通过调节损伤部位核小体密度来调控 HR。机制研究表明，BRG1 的 ATP 酶结构域和 SIRT1 的 ZnF 结构域与 DNA 损伤后的聚 ADP 核糖 (PAR) 相互作用，负责将这两个因素带到断裂的 DNA 末端。在 DNA 损伤部位，BRG1 和 SIRT1 相互作用，随后 SIRT1 在赖氨酸残基 1029 和 1033 处使 BRG1 去乙酰化，刺激其 ATP 酶活性重塑染色质并促进 HR。
