Department of Environment and Primary Prevention, Section of Experimental and Computational Carcinogenesis and Section of Molecular Epidemiology, Istituto Superiore di Sanità, Rome, Italy.
EMBO J. 2010 Sep 15;29(18):3156-69. doi: 10.1038/emboj.2010.205. Epub 2010 Aug 27.
Accurate response to replication arrest is crucial to preserve genome stability and requires both the ATR and ATM functions. The Werner syndrome protein (WRN) is implicated in the recovery of stalled replication forks, and although an ATR/ATM-dependent phosphorylation of WRN was observed after replication arrest, the function of such modifications during the response to perturbed replication is not yet appreciated. Here, we report that WRN is directly phosphorylated by ATR at multiple C-terminal S/TQ residues. Suppression of ATR-mediated phosphorylation of WRN prevents proper accumulation of WRN in nuclear foci, co-localisation with RPA and causes breakage of stalled forks. On the other hand, inhibition of ATM kinase activity or expression of an ATM-unphosphorylable WRN allele leads to retention of WRN in nuclear foci and impaired recruitment of RAD51 recombinase resulting in reduced viability after fork collapse. Altogether, our findings indicate that ATR and ATM promote recovery from perturbed replication by differently regulating WRN at defined moments of the response to replication fork arrest.
准确响应复制停滞对于维持基因组稳定性至关重要，这需要 ATR 和 ATM 功能。 Werner 综合征蛋白 (WRN) 被认为参与修复停滞的复制叉，尽管在复制停滞后观察到 WRN 的 ATR/ATM 依赖性磷酸化，但在对受干扰的复制的反应中，这些修饰的功能尚不清楚。在这里，我们报告 WRN 可被 ATR 在多个 C 末端 S/TQ 残基上直接磷酸化。抑制 WRN 的 ATR 介导的磷酸化可防止 WRN 在核焦点中的适当积累，与 RPA 共定位，并导致停滞的叉断裂。另一方面，抑制 ATM 激酶活性或表达 ATM 不可磷酸化的 WRN 等位基因导致 WRN 在核焦点中的保留，并损害 RAD51 重组酶的募集，导致叉崩溃后存活能力降低。总之，我们的研究结果表明，ATR 和 ATM 通过在复制叉停滞反应的特定时刻以不同的方式调节 WRN 来促进从受干扰的复制中恢复。
