The p53 response to DNA damage in vivo is independent of DNA-dependent protein kinase
The p53 response to DNA damage in vivo is independent of DNA-dependent protein kinase
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DOI：
10.1128/mcb.20.11.4075-4083.2000
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发表时间：
2000-06-01
影响因子：
5.3
通讯作者：
Merlino, G
中科院分区：
文献类型：
--
作者：
Jhappan, C;Yusufzai, TM;Merlino, G
电离辐射（IR）暴露导致哺乳动物细胞经历p53依赖性细胞周期阻滞和/或凋亡。DNA依赖性蛋白激酶（DNA- pk）在DNA损伤信号转导到p53中的体内作用仍未得到解决。为了确定DNA-PK和p53之间的关系，我们研究了DNA-PK缺乏小鼠的细胞周期和对IR的凋亡反应。使用含有DNA-PK催化亚基失活突变（DNA-PKcs）的滑动小鼠，我们不仅证明了这些DNA-PKcs无效突变体具有高度放射敏感性，而且在IR处理后，p53在培养的细胞和组织中积累。诱导的p53具有转录活性，并介导滑脱细胞中p21和Bar的诱导。胸腺细胞周期对IR治疗反应的检测表明，滑动G(1)/ s期细胞周期检查点功能完好无损。我们进一步表明，与野生型小鼠相比，slip小鼠表现出更高水平的自发性胸腺凋亡，以及对IR更强的凋亡反应。总之，这些数据表明，p53介导的DNA损伤反应在缺乏DNA- pk活性的细胞中是完整的，并表明其他激酶，如在共济失调毛细血管扩张中突变的基因产物（ATM），是调节ir诱导的p53磷酸化和积累的更好候选。
Ionizing radiation (IR) exposure causes mammalian cells to undergo p53-dependent cell cycle arrest and/or apoptosis. The in vivo role of DNA-dependent protein kinase (DNA-PK) in the transduction of the DNA damage signal to p53 remains unresolved. To determine the relationship between DNA-PK and p53, we studied the cell cycle and apoptotic responses to IR in mice deficient in DNA-PK. Using the slip mouse, which harbors an inactivating mutation of the DNA-PK catalytic subunit (DNA-PKcs), we demonstrated not only that these DNA-PKcs null mutants were highly radiosensitive but also that upon IR treatment, p53 accumulated in their cultured cells and tissue. Induced p53 was transcriptionally active and mediated the induction of p21 and Bar in slip cells. Examination of the thymic cell cycle response to IR treatment indicated that the slip G(1)/S-phase cell cycle checkpoint function was intact. We further show that slip mice exhibited a higher level of spontaneous thymic apoptosis as well as a more robust apoptotic response to IR than wild-type mice. Together, these data demonstrate that the p53-mediated response to DNA damage is intact in cells devoid of DNA-PK activity and suggest that other kinases, such as the product of the gene (ATM) mutated in ataxia telangiectasia, are better candidates for regulating IR-induced phosphorylation and accumulation of p53.