The ataxia-telangiectasia related protein ATR mediates DNA-dependent phosphorylation of p53
The ataxia-telangiectasia related protein ATR mediates DNA-dependent phosphorylation of p53
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DOI：
10.1038/sj.onc.1202973
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发表时间：
1999-07-08
期刊：
影响因子：
8
通讯作者：
Jackson, SP
中科院分区：
文献类型：
--
作者：
Lakin, ND;Hann, BC;Jackson, SP
肿瘤抑制蛋白p53的水平响应于多种DNA损伤剂而增加。DNA损伤诱导的p53磷酸化发生在体内丝氨酸-15。p53在丝氨酸-15处的磷酸化通过抑制其与Mdm 2的相互作用而导致多肽的稳定，Mdm 2是靶向p53进行泛素依赖性降解的蛋白质。然而，DNA损伤向p53发出信号的机制仍不清楚。在这里，我们报告了一种新的DNA激活的蛋白激酶，磷酸化p53丝氨酸-15，HeLa细胞核提取物的分级和生化分析表明，这种激酶是不同于DNA依赖的蛋白激酶（DNA-PK），并对应于人类细胞周期检查点蛋白ATR。重组ATR的免疫沉淀研究表明，这种多肽的催化活性是必需的DNA刺激的p53丝氨酸-15磷酸化。这些数据表明，ATR可能在DNA损伤后启动的信号转导级联中的p53上游起作用，并提供了ATR活性的生化测定系统。
Levels of the tumour suppressor protein p53 are increased in response to a variety of DNA damaging agents. DNA damage-induced phosphorylation of p53 occurs at serine-15 in vivo. Phosphorylation of p53 at serine-15 leads to a stabilization of the polypeptide by inhibiting its interaction with Mdm2, a protein that targets p53 for ubiquitin-dependent degradation, However, the mechanisms by which DNA damage is signalled to p53 remain unclear. Here, we report the identification of a novel DNA-activated protein kinase that phosphorylates p53 on serine-15, Fractionation of HeLa nuclear extracts and biochemical analyses indicate that this kinase is distinct from the DNA-dependent protein kinase (DNA-PK) and corresponds to the human cell cycle checkpoint protein ATR. Immunoprecipitation studies of recombinant ATR reveal that catalytic activity of this polypeptide is required for DNA-stimulated phosphorylation of p53 on serine-15. These data suggest that ATR may function upstream of p53 in a signal transduction cascade initiated upon DNA damage and provide a biochemical assay system for ATR activity.