Topoisomerase I poisoning results in PARP-mediated replication fork reversal
Topoisomerase I poisoning results in PARP-mediated replication fork reversal
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DOI：
10.1038/nsmb.2258
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发表时间：
2012-04-01
影响因子：
16.8
通讯作者：
Lopes, Massimo
中科院分区：
文献类型：
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作者：
Chaudhuri, Arnab Ray;Hashimoto, Yoshitami;Lopes, Massimo
拓扑异构酶 I (Top1) 在 DNA 复制和转录过程中释放扭转应力，并被喜树碱和喜树碱衍生的癌症化疗药物抑制。 Top1 抑制剂的细胞毒性通常与双链断裂 (DSB) 的形成有关，这是由于 Top1 被捕获在复制细胞中带切口的 DNA 中间体上而导致的。在这里，我们使用酵母、哺乳动物细胞系和非洲爪蟾卵提取物来证明 Top1 毒物迅速诱导复制叉减慢和逆转，这可以在亚致死抑制剂剂量下与 DSB 形成解偶联。有效的叉逆转需要聚（ADP-核糖）聚合酶活性，但一般不需要单链断裂修复，并限制 DSB 形成。这些数据将分叉逆转确定为防止外源复制应激时染色体断裂的一种手段，并暗示参与分叉逆转或重新启动的蛋白质是调节复制应激诱导化疗药物的细胞毒性的因素。
Topoisomerase I (Top1) releases torsional stress during DNA replication and transcription and is inhibited by camptothecin and camptothecin-derived cancer chemotherapeutics. Top1 inhibitor cytotoxicity is frequently linked to double-strand break (DSB) formation as a result of Top1 being trapped on a nicked DNA intermediate in replicating cells. Here we use yeast, mammalian cell lines and Xenopus laevis egg extracts to show that Top1 poisons rapidly induce replication-fork slowing and reversal, which can be uncoupled from DSB formation at sublethal inhibitor doses. Poly(ADP-ribose) polymerase activity, but not single-stranded break repair in general, is required for effective fork reversal and limits DSB formation. These data identify fork reversal as a means to prevent chromosome breakage upon exogenous replication stress and implicate proteins involved in fork reversal or restart as factors modulating the cytotoxicity of replication stress-inducing chemotherapeutics.