PDF(Pubmed)
Abstract：
Replication stress compromises genomic integrity. Fork blocking lesions such as those induced by cisplatin and other chemotherapeutic agents arrest replication forks. Repriming downstream of these lesions represents an important mechanism of replication restart, however the single stranded DNA (ssDNA) gaps left behind, unless efficiently filled, can serve as entry point for nucleases. Nascent strand gaps can be repaired by BRCA-mediated homology repair. Alternatively, gaps can also be filled by translesion synthesis (TLS) polymerases. How these events are regulated is still not clear. Here, we show that PARP10, a poorly-characterized mono-ADP-ribosyltransferase, is recruited to nascent strand gaps to promote their repair. PARP10 interacts with the ubiquitin ligase RAD18 and recruits it to these structures, resulting in the ubiquitination of the replication factor PCNA. PCNA ubiquitination, in turn, recruits the TLS polymerase REV1 for gap filling. We show that PARP10 recruitment to gaps and the subsequent REV1-mediated gap filling requires both the catalytic activity of PARP10, and its ability to interact with PCNA. We moreover show that PARP10 is hyperactive in BRCA-deficient cells, and its inactivation potentiates gap accumulations and cytotoxicity in these cells. Our work uncovers PARP10 as a regulator of ssDNA gap filling, which promotes genomic stability in BRCA-deficient cells.
摘要：
复制应激损害基因组完整性。叉阻断病变，例如顺铂和其他化学治疗剂引起的病变，会阻止复制叉。在这些病变的下游重新灌注代表了复制重新开始的重要机制，然而，单链DNA（ssDNA）的空白留下，除非有效填充，可以作为核酸酶的入口点。新生的链缺口可以通过BRCA介导的同源性修复来修复。或者，间隙也可以通过跨损伤合成(TLS)聚合酶来填充。这些事件如何被监管仍然不清楚。这里,我们发现PARP10是一种特征不佳的单ADP核糖基转移酶，被招募到新生的链间隙以促进其修复。PARP10与泛素连接酶RAD18相互作用，并将其招募到这些结构中，导致复制因子PCNA的泛素化。PCNA泛素化，反过来,招募TLS聚合酶REV1来填补空白。我们表明，PARP10募集到缺口和随后的REV1介导的缺口填充既需要PARP10的催化活性，也需要其与PCNA相互作用的能力。此外，我们表明PARP10在BRCA缺陷细胞中过度活跃，它的失活增强了这些细胞的间隙积累和细胞毒性。我们的工作揭示了PARP10作为ssDNA缺口填充的调节剂，这促进了BRCA缺陷细胞的基因组稳定性。
