Woo R A, McLure K G, Lees-Miller S P, Rancourt D E, Lee P W
Department of Microbiology and Infectious Diseases, University of Calgary, Alberta, Canada.
Nature. 1998 Aug 13;394(6694):700-4. doi: 10.1038/29343.
The tumour suppressor p53 becomes activated as a transcription factor in response to DNA damage, but the mechanism for this activation is unclear. A good candidate for an upstream activator of p53 is the DNA-dependent protein kinase (DNA-PK) that depends on the presence of DNA breaks for its activity. Here we investigate the link between DNA damage and the activation of DNA-PK and of p53. To determine whether DNA-PK is an upstream mediator of the p53 DNA-damage response, we analysed a severe combined-immunodeficiency (SCID) mouse cell line, SCGR11, and the human glioma cell line M059J . Both cell lines lack any detectable DNA-PK activity. We find that p53 is incapable of binding to DNA in the absence of DNA-PK, that DNA-PK is necessary but not sufficient for activation of p53 sequence-specific DNA binding, and that this activation occurs in response to DNA damage. Our results establish DNA-PK as a link between DNA damage and p53 activation, and reveal the existence of a mammalian DNA-damage-response pathway.
肿瘤抑制因子p53作为转录因子会在DNA损伤时被激活，但其激活机制尚不清楚。p53上游激活因子的一个有力候选者是DNA依赖性蛋白激酶（DNA-PK），其活性依赖于DNA断裂的存在。在此，我们研究DNA损伤与DNA-PK及p53激活之间的联系。为了确定DNA-PK是否为p53 DNA损伤反应的上游介质，我们分析了严重联合免疫缺陷（SCID）小鼠细胞系SCGR11和人胶质瘤细胞系M059J。这两种细胞系均缺乏任何可检测到的DNA-PK活性。我们发现，在没有DNA-PK的情况下，p53无法与DNA结合，DNA-PK对于激活p53序列特异性DNA结合是必要的，但并不充分，且这种激活是对DNA损伤的反应。我们的结果确立了DNA-PK作为DNA损伤与p53激活之间的联系，并揭示了一种哺乳动物DNA损伤反应途径的存在。
