Transcription-independent suppression of DNA synthesis by p53 in sperm-irradiated mouse zygotes
Transcription-independent suppression of DNA synthesis by p53 in sperm-irradiated mouse zygotes
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DOI：
10.1038/sj.onc.1208514
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发表时间：
2005-05
期刊：
影响因子：
8
通讯作者：
M. Toyoshima;T. Shimura;S. Adiga;M. Taga;K. Shiraishi;M. Inoue;Zhi-Min Yuan;O. Niwa
中科院分区：
文献类型：
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作者：
M. Toyoshima;T. Shimura;S. Adiga;M. Taga;K. Shiraishi;M. Inoue;Zhi-Min Yuan;O. Niwa
在高等真核生物中，响应DNA损伤的细胞周期阻滞对于维持基因组完整性是重要的。我们之前已经报道了新的p53依赖性s期检查点在辐照精子受精的小鼠受精卵中起作用。在本研究中，我们分析了小鼠受精卵s期检查点所需的p53功能的细节。结果表明，ATM激酶可能是p53依赖性s期检查点不可或缺的，因为它的抑制作用被咖啡因和wortmannin等抑制剂所消除。然而，当将ATM磷酸化位点突变蛋白微注射到缺乏功能性p53的精子辐照受精卵中时，仍然能够抑制DNA合成，这表明磷酸化的目标不是p53。此外，α-amanitin的抑制作用不受α-amanitin的影响，在转录激活区域突变的p53蛋白也有抑制DNA合成的功能。然而，在dna结合区域突变的p53蛋白缺乏抑制活性。综上所述，与dna结合域相关的p53的转录不依赖功能与另一个未知靶蛋白协同参与s期检查点。
Cell cycle arrest in response to DNA damage is important for the maintenance of genomic integrity in higher eukaryotes. We have previously reported the novel p53-dependent S-phase checkpoint operating in mouse zygotes fertilized with irradiated sperm. In the present study, we analysed the detail of the p53 function required for this S-phase checkpoint in mouse zygotes. The results indicate that ATM kinase is likely to be indispensable for the p53-dependent S-phase checkpoint since the suppression was abrogated by inhibitors such as caffeine and wortmannin. However, ATM phosphorylation site mutant proteins were still capable of suppressing DNA synthesis when microinjected into sperm-irradiated zygotes lacking the functional p53, suggesting that the target of the phosphorylation is not p53. In addition, the suppression was not affected by α-amanitin, and p53 protein mutated at the transcriptional activation domain was also functional in the suppression of DNA synthesis. However, p53 proteins mutated at the DNA-binding domain were devoid of the suppressing activity. Taken together, the transcription-independent function of p53 associated with the DNA-binding domain is involved in the S-phase checkpoint in collaboration with yet another unidentified target protein (s).