Mitchell Cancer Institute, University of South Alabama, Mobile, AL 36604, USA; Department of Pharmacology, College of Medicine, University of South Alabama, Mobile, AL 36604, USA.
Mitchell Cancer Institute, University of South Alabama, Mobile, AL 36604, USA.
Cell Rep. 2021 Nov 2;37(5):109917. doi: 10.1016/j.celrep.2021.109917.
Assembly and disassembly of DNA repair protein complexes at DNA damage sites are essential for maintaining genomic integrity. Investigating factors coordinating assembly of the base excision repair (BER) proteins DNA polymerase β (Polβ) and XRCC1 to DNA lesion sites identifies a role for Polβ in regulating XRCC1 disassembly from DNA repair complexes and, conversely, demonstrates Polβ's dependence on XRCC1 for complex assembly. LivePAR, a genetically encoded probe for live-cell imaging of poly(ADP-ribose) (PAR), reveals that Polβ and XRCC1 require PAR for repair-complex assembly, with PARP1 and PARP2 playing unique roles in complex dynamics. Further, BER complex assembly is modulated by attenuation/augmentation of NAD biosynthesis. Finally, SIRT6 does not modulate PARP1 or PARP2 activation but does regulate XRCC1 recruitment, leading to diminished Polβ abundance at sites of DNA damage. These findings highlight coordinated yet independent roles for PARP1, PARP2, and SIRT6 and their regulation by NAD bioavailability to facilitate BER.
DNA 修复蛋白复合物在 DNA 损伤部位的组装和拆卸对于维持基因组完整性至关重要。研究协调碱基切除修复 (BER) 蛋白 DNA 聚合酶 β (Polβ) 和 XRCC1 组装到 DNA 损伤部位的因素，鉴定了 Polβ 在调节 XRCC1 从 DNA 修复复合物中拆卸的作用，反之，也证明了 Polβ 对 XRCC1 组装复合物的依赖性。LivePAR 是一种用于活细胞多聚 ADP-核糖 (PAR) 成像的基因编码探针，表明 Polβ 和 XRCC1 需要 PAR 才能组装修复复合物，而 PARP1 和 PARP2 在复合物动力学中发挥独特作用。此外，BER 复合物的组装受到 NAD 生物合成的衰减/增强的调节。最后，SIRT6 不会调节 PARP1 或 PARP2 的激活，但会调节 XRCC1 的募集，导致 DNA 损伤部位的 Polβ 丰度降低。这些发现强调了 PARP1、PARP2 和 SIRT6 的协调但独立的作用，以及 NAD 生物利用度对其调节以促进 BER。
