冈崎碎片
增殖细胞核抗原
泛素
细胞生物学
DNA复制
复制后修复
DNA损伤
DNA修复
生物
分子生物学
DNA错配修复
DNA
真核细胞DNA复制
化学
遗传学
基因
作者
Tanay Thakar,Wendy Leung,Claudia M. Nicolae,Kristen E. Clements,Binghui Shen,Anja‐Katrin Bielinsky,George‐Lucian Moldovan
标识
DOI:10.1038/s41467-020-16096-w
摘要
Upon genotoxic stress, PCNA ubiquitination allows for replication of damaged DNA by recruiting lesion-bypass DNA polymerases. However, PCNA is also ubiquitinated during normal S-phase progression. By employing 293T and RPE1 cells deficient in PCNA ubiquitination, generated through CRISPR/Cas9 gene editing, here, we show that this modification promotes cellular proliferation and suppression of genomic instability under normal growth conditions. Loss of PCNA-ubiquitination results in DNA2-dependent but MRE11-independent nucleolytic degradation of nascent DNA at stalled replication forks. This degradation is linked to defective gap-filling in the wake of the replication fork and incomplete Okazaki fragment maturation, which interferes with efficient PCNA unloading by ATAD5 and subsequent nucleosome deposition by CAF-1. Moreover, concomitant loss of PCNA-ubiquitination and the BRCA pathway results in increased nascent DNA degradation and PARP inhibitor sensitivity. In conclusion, we show that by ensuring efficient Okazaki fragment maturation, PCNA-ubiquitination protects fork integrity and promotes the resistance of BRCA-deficient cells to PARP-inhibitors.
科研通智能强力驱动
Strongly Powered by AbleSci AI