Phosphorylation of p53: a novel pathway for p53 inactivation in human T-cell lymphotropic virus type 1-transformed cells
Phosphorylation of p53: a novel pathway for p53 inactivation in human T-cell lymphotropic virus type 1-transformed cells
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DOI：
10.1128/jvi.72.8.6348-6355.1998
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发表时间：
1998-08-01
影响因子：
5.4
通讯作者：
Brady, JN
中科院分区：
文献类型：
--
作者：
Pise-Masison, CA;Radonovich, M;Brady, JN
通过突变或与病毒或细胞转化蛋白相互作用抑制p53功能，与致癌潜力密切相关。只有一小部分人类T细胞嗜淋巴细胞病毒1型（HTLV-1）转化的细胞携带p53突变，突变的p53基因仅在四分之一的成人T细胞白血病病例中发现。在以前的研究中，我们证明了野生型p53在HTLV-1转化的细胞中是稳定的，并且转录不活跃。此外，病毒转录激活因子Tax通过涉及p53的前52个氨基酸的机制在p53的稳定和失活中起作用。在这里，我们首次表明，p53的磷酸化通过阻断其与基础转录因子的相互作用而使p53失活。使用二维肽图谱，我们证明了对应于氨基酸1至19和387至393的肽在HTLV-1转化的细胞中被过度磷酸化。此外，使用磷酸化Ser 15和Ser 392特异性抗体，我们证明了这些氨基酸的磷酸化增加。由于HTLV-1 p53以序列特异性方式结合DNA，但不能与TFIID相互作用，我们测试了p53 N末端的磷酸化是否影响p53-TFIID相互作用。使用生物素化的肽，我们表明，丝氨酸15磷酸化单独抑制p53-TFIID相互作用。相比之下，Ser 15和Ser 37的磷酸化恢复TFIID结合并阻断MDM 2结合。我们的研究为HTLV-1在体内利用p53的翻译后修饰来抑制肿瘤抑制蛋白的功能提供了证据。
Inhibition of p53 function, through either mutation or interaction with viral or cellular transforming proteins, correlates strongly with the oncogenic potential. Only a small percentage of human T cell lymphotropic virus type 1 (HTLV-1)-transformed cells carry p53 mutations, and mutated p53 genes have been found in only one-fourth of adult T-cell leukemia cases. In previous studies, we demonstrated that wild-type p53 is stabilized and transcriptionally inactive in HTLV-1-transformed cells. Further, the viral transcriptional activator Tax plays a role in both the stabilization and inactivation of p53 through a mechanism involving the first 52 amino acids of p53. Here we show for the first time that phosphorylation of p53 inactivates p53 by blocking its interaction with basal transcription factors. Using two-dimensional peptide mapping, we demonstrate that peptides corresponding to amino acids 1 to 19 and 387 to 393 are hyperphosphorylated in HTLV-1-transformed cells. Moreover, using antibodies specific for phosphorylated Ser15 and Ser392, we demonstrate increased phosphorylation of these amino acids. Since HTLV-1 p53 binds DNA in a sequence-specific manner but fails to interact with TFIID, we tested whether phosphorylation of the N terminus of p53 affected p53-TFIID interaction. Using biotinylated peptides, we show that phosphorylation of Ser15 alone inhibits p53-TFIID interaction. In contrast, phosphorylation at Ser15 and -37 restores TFIID binding and blocks MDM2 binding. Our studies provide evidence that HTLV-1 utilizes the posttranslational modification of p53 in vivo to inactivate function of the tumor suppressor protein.