Mechanistic differences in the transcriptional activation of p53 by 14-3-3 isoforms
Mechanistic differences in the transcriptional activation of p53 by 14-3-3 isoforms
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DOI：
10.1093/nar/gkp1041
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发表时间：
2010-01-01
影响因子：
14.9
通讯作者：
Fersht, Alan R.
中科院分区：
文献类型：
--
作者：
Rajagopalan, Sridharan;Sade, Robert S.;Fersht, Alan R.
p53通过启动参与细胞周期停滞、衰老、凋亡和DNA修复的基因的转录来维持基因组的完整性。p53的活性受翻译后修饰和蛋白质-蛋白质相互作用的调节。在S366、S378和T387处磷酸化的p53在体外结合14-3-3蛋白。在这里，我们表明，这些网站是潜在的14-3-3结合位点在体内。Epoxy（Sigma）和gamma（gamma）同种型需要在这些位点中的任一个处磷酸化以与p53有效相互作用，而对于sigma（Sigma）和tau（tau），这些位点是p53。此外，Sigma和tau与p53 C-末端磷酸肽的结合比Sigma和Gamma弱。然而，这四种异构体与二磷酸化p53 C-末端肽的结合比单磷酸化对应物紧密。有趣的是，所有研究的亚型转录激活野生型p53。Sigma和tau稳定了细胞中的p53水平，而Sigma和Gamma在体外刺激了p53-DNA结合活性。总体而言，结果表明，结构和功能相似的14-3-3亚型可能通过不同的机制发挥其对p53的调节潜力。我们讨论了14-3-3在p53稳定和激活特异性DNA结合中的亚型特异性作用。
p53 maintains genome integrity by initiating the transcription of genes involved in cell-cycle arrest, senescence, apoptosis and DNA repair. The activity of p53 is regulated by both post-translational modifications and protein-protein interactions. p53 that has been phosphorylated at S366, S378 and T387 binds 14-3-3 proteins in vitro. Here, we show that these sites are potential 14-3-3 binding sites in vivo. Epsilon (epsilon) and gamma (gamma) isoforms required phosphorylation at either of these sites for efficient interaction with p53, while for sigma (Sigma) and tau (tau) these sites are dispensable. Further, Sigma and tau bound more weakly to p53 C-terminal phosphopeptides than did epsilon and gamma. However, the four isoforms bound tightly to di-phosphorylated p53 C-terminal peptides than did the mono-phosphorylated counterparts. Interestingly, all the isoforms studied transcriptionally activated wild-type p53. Sigma and tau stabilized p53 levels in cells, while epsilon and gamma stimulated p53-DNA binding activity in vitro. Overall, the results suggest that structurally and functionally similar 14-3-3 isoforms may exert their regulatory potential on p53 through different mechanisms. We discuss the isoform-specific roles of 14-3-3 in p53 stabilization and activation of specific-DNA binding.