Department of Biochemistry and Molecular Biology, JH Quillen College of Medicine, East Tennessee State University, Johnson City, TN 37614, USA.
Oncogene. 2013 May 9;32(19):2452-62. doi: 10.1038/onc.2012.257. Epub 2012 Jul 16.
Homologous recombination (HR) and nonhomologous end joining (NHEJ) are two distinct DNA double-stranded break (DSB) repair pathways. Here, we report that DNA-dependent protein kinase (DNA-PK), the core component of NHEJ, partnering with DNA-damage checkpoint kinases ataxia telangiectasia mutated (ATM) and ATM- and Rad3-related (ATR), regulates HR repair of DSBs. The regulation was accomplished through modulation of the p53 and replication protein A (RPA) interaction. We show that upon DNA damage, p53 and RPA were freed from a p53-RPA complex by simultaneous phosphorylations of RPA at the N-terminus of RPA32 subunit by DNA-PK and of p53 at Ser37 and Ser46 in a Chk1/Chk2-independent manner by ATR and ATM, respectively. Neither the phosphorylation of RPA nor of p53 alone could dissociate p53 and RPA. Furthermore, disruption of the release significantly compromised HR repair of DSBs. Our results reveal a mechanism for the crosstalk between HR repair and NHEJ through the co-regulation of p53-RPA interaction by DNA-PK, ATM and ATR.
同源重组（HR）和非同源末端连接（NHEJ）是两种不同的 DNA 双链断裂（DSB）修复途径。在这里，我们报告说，非同源末端连接的核心组成部分 DNA 依赖性蛋白激酶（DNA-PK）与共济失调毛细血管扩张突变（ATM）和 ATM 和 Rad3 相关（ATR）的 DNA 损伤检查点激酶合作，调节 DSB 的 HR 修复。这种调节是通过调节 p53 和复制蛋白 A（RPA）的相互作用来实现的。我们表明，在 DNA 损伤后，p53 和 RPA 被 DNA-PK 在 RPA32 亚基的 N 端同时磷酸化，以及 ATR 和 ATM 分别以 Chk1/Chk2 非依赖性方式在 Ser37 和 Ser46 磷酸化，从而从 p53-RPA 复合物中释放出来。单独的 RPA 或 p53 的磷酸化都不能使 p53 和 RPA 解离。此外，释放的中断显著影响 DSB 的 HR 修复。我们的研究结果揭示了一种通过 DNA-PK、ATM 和 ATR 共同调节 p53-RPA 相互作用，在 HR 修复和 NHEJ 之间进行串扰的机制。
