The carboxy-terminal serine 392 phosphorylation site of human p53 is not required for wild-type activities.
The carboxy-terminal serine 392 phosphorylation site of human p53 is not required for wild-type activities.
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发表时间：
1994-11
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影响因子：
8
通讯作者：
Michele Fiscella;Nicola Zambrano;Stephen Ullrich;T. Unger;D. Lin;B. Cho;W. Mercer;Carl W. Anderson;E. Appella
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作者：
Michele Fiscella;Nicola Zambrano;Stephen Ullrich;T. Unger;D. Lin;B. Cho;W. Mercer;Carl W. Anderson;E. Appella
野生型p53通过激活基因转录和阻止细胞周期进程在G1 DNA损伤检查点途径中发挥作用。其他人报道小鼠p53中丝氨酸386密码子的突变消除了其抑制生长的能力。鼠p53的丝氨酸386和人p53的同源残基丝氨酸392在体内被磷酸化，并且可以在体外被酪蛋白激酶II（CKII）磷酸化。我们构建了突变体，改变丝氨酸392的人p53丙氨酸（p53-S392 A）或天冬氨酸（p53-S392 D）;这两个突变体与携带p53响应元件的报告基因共转染到p53无效的Saos-2细胞系激活转录以及野生型p53。此外，这两种突变体在这些细胞中瞬时转染后阻断了细胞周期进程。建立了T98 G人胶质母细胞瘤细胞系的稳定衍生物，其响应于地塞米松表达p53-S392 A。这种突变体的过表达激活了内源性waf 1（也称为cip 1）和mdm 2基因的转录，其程度与野生型p53相同，并且也产生了生长停滞。最后，p53-S392 A和p53-S392 D抑制灶的形成激活ras和腺病毒E1 A癌基因有效地做野生型p53。因此，与改变丝氨酸15磷酸化位点的突变体不同，消除丝氨酸392磷酸化位点对p53功能没有明显影响。我们的结论是，既不磷酸化，也不RNA连接到丝氨酸392所需的人p53的能力，抑制细胞生长或激活体内转录。
Wild-type p53 functions in the G1 DNA damage checkpoint pathway by activating gene transcription and preventing cell cycle progression. Others reported that mutation of the serine 386 codon in mouse p53 abolished its ability to suppress growth. Serine 386 of murine p53 and the homologous residue of human p53, serine 392, are phosphorylated in vivo and can be phosphorylated in vitro by casein kinase II (CKII). We constructed mutants that changed serine 392 of human p53 to alanine (p53-S392A) or aspartic acid (p53-S392D); cotransfection of both these mutants with a reporter gene carrying a p53-responsive element into the p53-null Saos-2 cell line activated transcription as well as did wild-type p53. Furthermore, both mutants blocked cell cycle progression after transient transfection in these cells. A stable derivative of the T98G human glioblastoma cell line was established that expressed p53-S392A in response to dexamethasone. Overexpression of this mutant activated transcription of the endogenous waf1 (also called cip1) and mdm2 genes to the same extent as wild-type p53 and also produced growth arrest. Finally, p53-S392A and p53-S392D suppressed foci formation by activated ras and adenovirus E1A oncogenes as efficiently as did wild-type p53. Thus, unlike mutants that altered the serine 15 phosphorylation site, elimination of the serine 392 phosphorylation site had no discernible effect on p53 function. We conclude that neither phosphorylation nor RNA attachment to serine 392 are required for human p53's ability to suppress cell growth or to activate transcription in vivo.