ATM controls the extent of DNA end resection by eliciting sequential posttranslational modifications of CtIP
ATM controls the extent of DNA end resection by eliciting sequential posttranslational modifications of CtIP
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DOI：
10.1073/pnas.2022600118
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发表时间：
2021-03-23
影响因子：
11.1
通讯作者：
Huang, Jun
中科院分区：
文献类型：
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作者：
Han, Jinhua;Wan, Li;Huang, Jun
DNA 末端切除是通过同源重组 (HR) 修复 DNA 双链断裂 (DSB) 的关键步骤。然而，控制同源定向修复 DSB 位点切除程度的机制仍不清楚。在这里，我们表明，在 DSB 诱导后，关键切除因子 CtIP 在赖氨酸 578 处被泛素样蛋白 SUMO 以 PIAS4 依赖性方式修饰。 CtIP SUMO 化发生在受损的染色质上，需要 ATM 蛋白激酶预先进行过度磷酸化。 SUMO 修饰的高度磷酸化 CtIP 被 SUMO 依赖性 E3 泛素连接酶 RNF4 靶向，进行多泛素化和随后的降解。因此，CtIP SUMOylation 的破坏会导致 CtIP 在 DSB 上异常积累，进而导致不受控制的过度切除、HR 缺陷以及细胞对 DSB 诱导剂的敏感性增加。这些发现揭示了一种先前未识别的调节机制，该机制可调节 DSB 处的 CtIP 活性，从而通过 CtIP 的 ATM 依赖性顺序翻译后修饰来调节末端切除的程度。
DNA end resection is a critical step in the repair of DNA double-strand breaks (DSBs) via homologous recombination (HR). However, the mechanisms governing the extent of resection at DSB sites undergoing homology-directed repair remain unclear. Here, we show that, upon DSB induction, the key resection factor CtIP is modified by the ubiquitin-like protein SUMO at lysine 578 in a PIAS4-dependent manner. CtIP SUMOylation occurs on damaged chromatin and requires prior hyperphosphorylation by the ATM protein kinase. SUMO-modified hyperphosphorylated CtIP is targeted by the SUMO-dependent E3 ubiquitin ligase RNF4 for polyubiquitination and subsequent degradation. Consequently, disruption of CtIP SUMOylation results in aberrant accumulation of CtIP at DSBs, which, in turn, causes uncontrolled excessive resection, defective HR, and increased cellular sensitivity to DSB-inducing agents. These findings reveal a previously unidentified regulatory mechanism that regulates CtIP activity at DSBs and thus the extent of end resection via ATM-dependent sequential posttranslational modification of CtIP.