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Transcriptional Regulation of the mdm2 Oncogene by p53 Requires TRRAP Acetyltransferase Complexes

机译:p53对mdm2癌基因的转录调控需要TRRAP乙酰转移酶复合物。

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The p53 tumor suppressor regulates the cellular response to genetic damage through its function as a sequence-specific transcription factor. Among the most well-characterized transcriptional targets of p53 is the mdm2 oncogene. Activation of mdm2 is critical in the p53 pathway because the mdm2 protein marks p53 for proteosome-mediated degradation, thereby providing a negative-feedback loop. Here we show that the ATM-related TRRAP protein functionally cooperates with p53 to activate mdm2 transcription. TRRAP is a component of several multiprotein acetyltransferase complexes implicated in both transcriptional regulation and DNA repair. In support of a role for these complexes in mdm2 expression, we show that transactivation of the mdm2 gene is augmented by pharmacological inhibition of cellular deacetylases. In vitro analysis demonstrates that p53 directly binds to a TRRAP domain previously shown to be an activator docking site. Furthermore, transfection of cells with antisense TRRAP blocks p53-dependent transcription of mdm2. Finally, using chromatin immunoprecipitation, we demonstrate direct p53-dependent recruitment of TRRAP to the mdm2 promoter, followed by increased histone acetylation. These findings suggest a model in which p53 directly recruits a TRRAP/acetyltransferase complex to the mdm2 gene to activate transcription. In addition, this study defines a novel biochemical mechanism utilized by the p53 tumor suppressor to regulate gene expression.
机译:p53肿瘤抑制因子通过其作为序列特异性转录因子的功能来调节细胞对遗传损伤的反应。 mdm2 癌基因是p53最有特色的转录靶标。 mdm2 的激活在p53途径中至关重要,因为mdm2蛋白将p53标记为蛋白体介导的降解,从而提供了负反馈回路。在这里,我们显示ATM相关的TRRAP蛋白在功能上与p53协同激活 mdm2 转录。 TRRAP是涉及转录调控和DNA修复的几种多蛋白乙酰转移酶复合物的组成部分。为了支持这些复合物在 mdm2 表达中的作用,我们表明 mdm2 基因的反式激活通过细胞脱乙酰基酶的药理学抑制作用得以增强。体外分析表明,p53直接结合到TRRAP域上,该域以前被证明是激活物停靠位点。此外,用反义TRRAP转染细胞可阻断 mdm2 的p53依赖性转录。最后,使用染色质免疫沉淀,我们证明了TRRAP直接p53依赖募集到 mdm2 启动子,随后组蛋白乙酰化增加。这些发现提示了一个模型,其中p53直接向 mdm2 基因募集TRRAP /乙酰转移酶复合物以激活转录。此外,这项研究定义了一种新的生化机制,可被p53肿瘤抑制因子用来调节基因表达。

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