Repression of glucocorticoid receptor transactivation and DNA binding of a glucocorticoid response element within the serum/glucocorticoid-inducible protein kinase (sgk) gene promoter by the p53 tumor suppressor protein.
Repression of glucocorticoid receptor transactivation and DNA binding of a glucocorticoid response element within the serum/glucocorticoid-inducible protein kinase (sgk) gene promoter by the p53 tumor suppressor protein.
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DOI：
10.1210/mend.11.3.9893
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发表时间：
1997-03
影响因子：
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通讯作者：
A. C. Maiyar;P. T. Phu;A. Huang;G. Firestone
中科院分区：
文献类型：
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作者：
A. C. Maiyar;P. T. Phu;A. Huang;G. Firestone
sgk 是丝氨酸/苏氨酸蛋白激酶家族的新成员，在 Rat2 成纤维细胞和乳腺上皮细胞中受血清和糖皮质激素的转录调节。使用一系列 sgk-CAT 对 sgk 启动子进行 5'-删除分析。 （氯霉素乙酰转移酶）嵌合报告基因质粒，定义了糖皮质激素反应区域，其中包含 -1000 至 -975 bp 之间的糖皮质激素反应元件 (sgkGRE)。 sgkGRE 与糖皮质激素受体特异性结合，足以在几种细胞系中赋予糖皮质激素对异源启动子的反应性。引人注目的是，共转染鼠或人野生型 p53（而非突变型 p53）抑制了地塞米松刺激的含有 sgkGRE 或共有 GRE 的报告质粒的反式激活。凝胶位移分析表明，体外合成的 p53 阻止糖皮质激素受体与 sgkGRE 以及共有 GRE 的结合。 p53 介导的对地塞米松诱导的 sgkGRE 活性的抑制需要 p53 蛋白的 DNA 结合和反式激活功能。通过暴露于紫外线，内源性 p53 的激活抑制了转染细胞中共有 GRE-CAT 报告质粒的糖皮质激素受体反式激活。相反，激活的糖皮质激素受体抑制p53的反式激活功能，而p53的反式阻抑基本上不受影响。所提供的数据表明 sgk 是一种主要的糖皮质激素反应性蛋白激酶基因，涉及类固醇受体信号传导和细胞磷酸化级联之间串扰的新途径。此外，我们的研究提供了 p53 和糖皮质激素受体反式激活功能相互干扰的第一个证据，可能是通过它们的直接相互作用。
sgk is a novel member of the serine/threonine protein kinase family that is transcriptionally regulated by serum and glucocorticoids in Rat2 fibroblasts and in mammary epithelial cells. 5'-Deletion analysis of the sgk promoter, using a series of sgk-CAT. (chloramphenicol acetyltransferase) chimeric reporter gene plasmids, defined a glucocorticoid-responsive region that contains a glucocorticoid response element (sgkGRE) between -1000 and -975 bp. The sgkGRE is specifically bound by glucocorticoid receptors and is sufficient to confer glucocorticoid responsiveness to a heterologous promoter in several cell lines. Strikingly, cotransfection of either the murine or human wild type p53, but not a mutant p53, repressed the dexamethasone-stimulated transactivation of reporter plasmids containing either the sgkGRE or a consensus GRE. Gel shift analysis revealed that in vitro synthesized p53 prevented binding of the glucocorticoid receptor both to the sgkGRE as well as to a consensus GRE. The p53-mediated repression of dexamethasone-induced sgkGRE activity required both the DNA binding and transactivation functions of the p53 protein. Activation of endogenous p53, by exposure to UV light, repressed the glucocorticoid receptor transactivation of a consensus GRE-CAT reporter plasmid in transfected cells. Conversely, activated glucocorticoid receptors suppressed the transactivation function of p53, while transrepression by p53 was largely unaffected. The presented data demonstrate that sgk is a primary glucocorticoid-responsive protein kinase gene that implicates a new pathway of cross-talk between steroid receptor signaling and cellular phosphorylation cascades. In addition, our study provides the first evidence of mutual interference of transactivation functions of p53 and the glucocorticoid receptor, possibly through their direct interaction.