Nuclear PTEN interferes with binding of Ku70 at double-strand breaks through post-translational poly(ADP-ribosyl)ation
Nuclear PTEN interferes with binding of Ku70 at double-strand breaks through post-translational poly(ADP-ribosyl)ation
复制标题
核 PTEN 通过翻译后聚 (ADP-核糖基) 化干扰双链断裂处 Ku70 的结合
DOI：
10.1016/j.bbamcr.2016.10.003
复制
发表时间：
2016-12-01
影响因子：
5.1
通讯作者：
Mao, Weifeng
中科院分区：
文献类型：
--
作者：
Guan, Jiawei;Zhao, Qian;Mao, Weifeng
PTEN是一种肿瘤抑制基因，其特征是一种磷酸酶，可以拮抗细胞质中的磷脂酰肌醇3-激酶信号通路。核PTEN在染色体稳定性中起重要作用，其中由同源重组(HR)和非同源末端连接(NHEJ)介导的双链断裂(DSB)修复是至关重要的。因此，本研究探讨了核PTEN在DSB修复中的作用及其分子机制。利用人乳腺癌BT549和MDA-MB-231细胞株，我们揭示了PTEN控制Ku70的聚(ADP-核糖基)合成并干扰Ku70在DSB的结合的特异性。以质粒为基础的末端连接和报告分析表明，核PTEN抑制NHEJ的作用。电泳迁移率改变分析表明，核PTEN使Ku70复合体与DSB的结合减少了3倍。免疫共沉淀实验显示，PTEN可调节Ku70的聚ADP核糖化，而不是直接与Ku70相互作用，而PTEN促进PARP1的聚ADP核糖化，并诱导PARP1降解。值得注意的是，PI EN在DSB修复中的作用主要取决于它的核定位，而不是它的磷酸酶活性。因此，核PTEN的缺失而不是磷酸酶阴性的PTEN使细胞对抗肿瘤DNA损伤药物具有超敏反应。这一发现有助于理解PTEN在DSB修复中的作用，并使用特定的抗肿瘤DSB药物来治疗具有异常PTEN的肿瘤细胞。(C)2016爱思唯尔B.V.保留所有权利。
PTEN is a tumor suppressor gene characterized as a phosphatase that antagonizes the phosphatidylinositol 3-kinase signaling pathway in the cytoplasm. Nuclear PTEN plays roles in chromosomal stability, in which the double-strand breaks (DSB) repair mediated by homologous recombination (HR) and non-homologous end joining (NHEJ) is critical. Herein, the role of nuclear PTEN in DSB repair and the underlying molecular mechanism was investigated in this study. Using human breast cancer BT549 and MDA-MB-231 cell lines, we reveal a specific feature of PTEN that controls poly(ADP-ribosyl)ation of Ku70 and interferes with binding of Ku70 at DSB. Plasmid-based end joining and reporter assays showed that nuclear PTEN restrained NHEJ efficacy. Electrophoretic mobility shift assays showed that nuclear PTEN impaired Ku70 complex binding to DSB by 3-fold. Co-immunoprecipitation assay showed PTEN regulated poly(ADP-ribosyl)ation of Ku70 instead of directly interacting with Ku70, while PTEN promoted the poly(ADP-ribosyl)ation of PARP1 and induced the degradation of PARP1 in PTEN-WT cells exposed to DSB agents. Of note, the role of Pi EN in DSB repair mostly depends on its nuclear localization rather than its phosphatase activity. As a result, the absence of nuclear PTEN rather than phosphatase-negative PTEN confers cell hypersensitivity to anti-tumor DNA damage drugs. This finding contributes to understanding the effect of PTEN in repair of DSB and using defined anti-tumor DSB drugs to treat tumor cells with aberrant PTEN. (C) 2016 Elsevier B.V. All rights reserved.