Chabalier-Taste Corinne, Brichese Laetitia, Racca Carine, Canitrot Yvan, Calsou Patrick, Larminat Florence
University of Toulouse, UPS, Toulouse, France.
Institute of Pharmacology and Structural Biology, CNRS UMR 5089, Toulouse, France.
Oncotarget. 2016 Jan 19;7(3):2269-83. doi: 10.18632/oncotarget.6825.
Accurate repair of DNA double-strand breaks (DSB) caused during DNA replication and by exogenous stresses is critical for the maintenance of genomic integrity. There is growing evidence that the Polo-like kinase 1 (Plk1) that plays a number of pivotal roles in cell proliferation can directly participate in regulation of DSB repair. In this study, we show that Plk1 regulates BRCA1, a key mediator protein required to efficiently repair DSB through homologous recombination (HR). Following induction of DSB, BRCA1 concentrates in distinctive large nuclear foci at damage sites where multiple DNA repair factors accumulate. First, we found that inhibition of Plk1 shortly before DNA damage sensitizes cells to ionizing radiation and reduces DSB repair by HR. Second, we provide evidence that BRCA1 foci formation induced by DSB is reduced when Plk1 is inhibited or depleted. Third, we identified BRCA1 as a novel Plk1 substrate and determined that Ser1164 is the major phosphorylation site for Plk1 in vitro. In cells, mutation of Plk1 sites on BRCA1 significantly delays BRCA1 foci formation following DSB, recapitulating the phenotype observed upon Plk1 inhibition. Our data then assign a key function to Plk1 in BRCA1 foci formation at DSB, emphasizing Plk1 importance in the HR repair of human cells.
准确修复DNA复制过程中以及外源压力导致的DNA双链断裂（DSB）对于维持基因组完整性至关重要。越来越多的证据表明，在细胞增殖中发挥多种关键作用的Polo样激酶1（Plk1）可直接参与DSB修复的调控。在本研究中，我们表明Plk1可调控BRCA1，BRCA1是通过同源重组（HR）有效修复DSB所需的关键介导蛋白。DSB诱导后，BRCA1聚集在损伤部位独特的大核灶中，多个DNA修复因子在该部位积累。首先，我们发现DNA损伤前不久抑制Plk1会使细胞对电离辐射敏感，并减少HR介导的DSB修复。其次，我们提供证据表明，抑制或耗尽Plk1时，DSB诱导的BRCA1灶形成会减少。第三，我们将BRCA1鉴定为一种新的Plk1底物，并确定Ser1164是体外Plk1的主要磷酸化位点。在细胞中，BRCA1上Plk1位点的突变会显著延迟DSB后BRCA1灶的形成，重现了Plk1抑制后观察到的表型。我们的数据随后赋予了Plk1在DSB处BRCA1灶形成中的关键功能，强调了Plk1在人类细胞HR修复中的重要性。
