Differential phosphorylation of DNA-PKcs regulates the interplay between end-processing and end-ligation during nonhomologous end-joining.
Differential phosphorylation of DNA-PKcs regulates the interplay between end-processing and end-ligation during nonhomologous end-joining.
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DNA-PKcs 的差异磷酸化调节非同源末端连接过程中末端加工和末端连接之间的相互作用。
DOI：
10.1016/j.molcel.2015.02.024
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发表时间：
2015-04-02
期刊：
影响因子：
16
通讯作者：
Zha S
中科院分区：
文献类型：
--
作者：
Jiang W;Crowe JL;Liu X;Nakajima S;Wang Y;Li C;Lee BJ;Dubois RL;Liu C;Yu X;Lan L;Zha S
非同源末端连接(NHEJ)是真核生物中保守的一种主要的DNA双链断裂修复途径。在脊椎动物中，NHEJ除了直接末端连接外，还进一步获得末端加工能力(例如，发夹开口)。DNA-PK催化亚基(DNA-PKcs)是一种脊椎动物特有的NHEJ因子，可被ATM激酶自身磷酸化或反式磷酸化。使用表达KDDNA-PKcs蛋白的小鼠模型，我们表明ATM介导的DNA-PKcs的反式磷酸化在Artemis招募水平上调节末端加工，而严格的DNA-PKcs的自动磷酸化是必要的，以解除DNA-PKcs蛋白本身对末端连接的物理阻碍。相应地，DNA-PKcsKD/KD小鼠和细胞显示出严重的末端连接缺陷和依赖于P53和Ku的胚胎致死性，但开放的发夹密封末端通常存在ATM激酶活性。综上所述，我们的发现确认DNA-PKcs是通过差异磷酸化来协调DNA末端的末端加工和末端连接的分子开关。
Non-homologous end-joining (NHEJ) is a major DNA double strand break repair pathway that is conserved in eukaryotes. In vertebrates, NHEJ further acquires end-processing capacities (e.g., hairpin opening) in addition to direct end-ligation. The catalytic subunit of DNA-PK (DNA-PKcs) is a vertebrate specific NHEJ factor that can be auto-phosphorylated or trans-phosphorylated by ATM kinase. Using a mouse model expressing a kinase-dead (KD) DNA-PKcs protein, we show that ATM-mediated trans-phosphorylation of DNA-PKcs regulates end-processing at the level of Artemis recruitment, while strictly auto-phosphorylation of DNA-PKcs is necessary to relieve the physical blockage on end-ligation imposed by the DNA-PKcs protein itself. Accordingly, DNA-PKcsKD/KD mice and cells show severe end-ligation defects and p53- and Ku-dependent embryonic lethality, but open hairpin-sealed ends normally in the presence of ATM kinase activity. Together, our findings identify DNA-PKcs as the molecular switch that coordinates end-processing and end-ligation at the DNA ends through differential phosphorylations.