Li Yuwen, Piao Longzhen, Yang Keum-Jin, Shin Sanghee, Shin Eulsoon, Park Kyung Ah, Byun Hee Sun, Won Minho, Choi Byung Lyul, Lee Hyunji, Kim Young-Rae, Hong Jang Hee, Hur Gang Min, Kim Jeong-Lan, Cho Jae Youl, Seok Jeong Ho, Park Jongsun
13Department of Pharmacology, Cell Signaling Laboratory, Research Center for Transgenic Cloned Pigs, Daejeon Regional Cancer Center, Cancer Research Institute, Research Institute for Medical Sciences, Korea.
23Department of Psychiatry, College of Medicine, Chungnam National University, Taejeon, 301-131 Korea.
Toxicol Res. 2008 Sep;24(3):175-182. doi: 10.5487/TR.2008.24.3.175. Epub 2008 Sep 1.
DNA-dependent protein kinase (DNA-PK) is involved in joining DNA double-strand breaks induced by ionizing radiation or V(D)J recombination and is activated by DNA ends and composed of a DNA binding subunit, Ku, and a catalytic subunit, DNA-PKcs. It has been suggested that DNA-PK might be 2 upstream kinase for protein kinase B (PKB). In this report, we showed that Ser473 phosphorylation in the hydrophobic-motif of PKB is blocked in DNA-PK knockout mouse embryonic fibroblast cells (MEFs) following insulin stimulation, while there is no effect on Ser473 phosphorylation in DNA-PK wild type MEF cells. The observation is further confirmed in human glioblastoma cells expressing a mutant form of DNA-PK (M059J) and a wild-type of DNA-PK (M059K), indicating that DNA-PK is indeed important for PKB activation. Furthermore, the treatment of cells with doxorubicin, DNA-damage inducing agent, leads to PKB phosphorylation on Ser473 in control MEF cells while there is no response in DNA-PK knockout MEF cells. Together, these results proposed that DNA-PK has a potential role in insulin signaling as well as DNA-repair signaling pathway.
DNA依赖性蛋白激酶（DNA-PK）参与连接由电离辐射或V（D）J重组诱导的DNA双链断裂，并由DNA末端激活，它由一个DNA结合亚基Ku和一个催化亚基DNA-PKcs组成。有人提出DNA-PK可能是蛋白激酶B（PKB）的上游激酶。在本报告中，我们发现，胰岛素刺激后，DNA-PK基因敲除的小鼠胚胎成纤维细胞（MEF）中，PKB疏水基序中的Ser473磷酸化被阻断，而在DNA-PK野生型MEF细胞中，Ser473磷酸化不受影响。在表达DNA-PK突变形式（M059J）和野生型DNA-PK（M059K）的人胶质母细胞瘤细胞中，这一观察结果得到了进一步证实，表明DNA-PK对PKB的激活确实很重要。此外，用阿霉素（一种DNA损伤诱导剂）处理细胞，可导致对照MEF细胞中Ser473处的PKB磷酸化，而在DNA-PK基因敲除的MEF细胞中则无反应。总之，这些结果表明DNA-PK在胰岛素信号传导以及DNA修复信号通路中具有潜在作用。
