Sequential role of RAD51 paralog complexes in replication fork remodeling and restart
Sequential role of RAD51 paralog complexes in replication fork remodeling and restart
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DOI：
10.1038/s41467-020-17324-z
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发表时间：
2020-07-15
影响因子：
16.6
通讯作者：
Lopes, Massimo
中科院分区：
文献类型：
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作者：
Berti, Matteo;Teloni, Federico;Lopes, Massimo
同源重组 (HR) 因子最近与 DNA 复制叉重塑和保护有关。在保持基因组稳定性的同时，HR 介导的分叉重塑通过迄今难以捉摸的机制促进癌症化疗耐药性。五种 HR 辅因子——RAD51 旁系同源物 RAD51B、RAD51C、RAD51D、XRCC2 和 XRCC3——最近成为重要的肿瘤抑制因子。尽管在 DNA 修复中得到了广泛的表征，但它们在复制中的作用尚未得到系统的解决。在这里，我们鉴定了所有 RAD51 旁系同源物，同时筛选复制应激时 RAD51 重组酶的调节剂。对同基因细胞系统中的分叉进展和结构的单分子分析表明，BCDX2 子复合物在应激时抑制分叉进展，促进分叉逆转。因此，BCDX2 会引发 BRCA2 缺陷细胞中反向叉的意外降解，从而增加基因组的不稳定性。相反，CX3 子复合体对于分叉反转来说是可有可无的，但可以调解反转分叉的有效重启。我们建议 RAD51 旁系同源在复制叉上顺序编排临床相关事务，共同促进复制叉重塑和重启。复制压力与复制中间体短暂重塑为反向分叉，然后有效的分叉重新启动有关。在这里，作者系统地分析了 RAD51 旁系同源物在这些交易中的作用，提供了关于这些蛋白质不同复合物的机制作用的见解。
Homologous recombination (HR) factors were recently implicated in DNA replication fork remodeling and protection. While maintaining genome stability, HR-mediated fork remodeling promotes cancer chemoresistance, by as-yet elusive mechanisms. Five HR cofactors - the RAD51 paralogs RAD51B, RAD51C, RAD51D, XRCC2 and XRCC3 - recently emerged as crucial tumor suppressors. Albeit extensively characterized in DNA repair, their role in replication has not been addressed systematically. Here, we identify all RAD51 paralogs while screening for modulators of RAD51 recombinase upon replication stress. Single-molecule analysis of fork progression and architecture in isogenic cellular systems shows that the BCDX2 subcomplex restrains fork progression upon stress, promoting fork reversal. Accordingly, BCDX2 primes unscheduled degradation of reversed forks in BRCA2-defective cells, boosting genomic instability. Conversely, the CX3 subcomplex is dispensable for fork reversal, but mediates efficient restart of reversed forks. We propose that RAD51 paralogs sequentially orchestrate clinically relevant transactions at replication forks, cooperatively promoting fork remodeling and restart. Replication stress has been associated with transient remodelling of replication intermediates into reversed forks, followed by efficient fork restart. Here the authors systematically analyse the role of RAD51 paralogs in these transactions, providing insights on the mechanistic role of different complexes of these proteins.