Tumor Necrosis Factor-α-mediated Regulation of the Inositol 1,4,5-Trisphosphate Receptor Promoter
Tumor Necrosis Factor-α-mediated Regulation of the Inositol 1,4,5-Trisphosphate Receptor Promoter
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DOI：
10.1074/jbc.m109.034504
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发表时间：
2009-10-02
影响因子：
4.8
通讯作者：
Bowers, William J.
中科院分区：
文献类型：
--
作者：
Park, Keigan M.;Yule, David I.;Bowers, William J.
肿瘤坏死因子- α (tnf - α)是一种促炎细胞因子，在多种体内平衡和病理过程中被认为是一种中心介质。信号在其细胞同源受体的下游级联，以及由此产生的转录反应，已经引起了人们对这些信号如何影响细胞生理学的强烈兴趣。值得注意的是，tnf - α被证明通过增强1型肌醇1,4,5-三磷酸受体（IP3R）稳态mRNA水平来增强神经元Ca2+信号。在目前的研究中，我们试图确定启动子区域最终对tnf - α暴露有反应。我们报道了一个包含特异性蛋白1 （SP-1）结合位点的序列是tnf - α调控所必需的。电泳迁移率转移分析证明了与该序列的特异性结合，而该位点的定点突变既取消了jnk介导的调节，也取消了转录因子结合。显性阴性SP-1的表达消除了启动子活性的增强和tnf - α暴露时ip3r介导的Ca2+信号的升高。总的来说，这些数据描绘了神经元环境中tnf - α调节IP3R表达和细胞内Ca2+稳态的关键途径。
Tumor necrosis factor-alpha (TNF-alpha), a proinflammatory cytokine, has been implicated as a central mediator in multiple homeostatic and pathologic processes. Signaling cascades downstream of its cellular cognate receptors, as well as the resultant transcriptional responses have received intense interest in regards to how such signals impact cellular physiology. Notably, TNF-alpha was shown to potentiate neuronal Ca2+ signaling by enhancing type-1 inositol 1,4,5-trisphosphate receptor (IP3R) steady-state mRNA levels. In the present study, we sought to determine the promoter region ultimately responsive to TNF-alpha exposure. We report that a sequence encompassing a specificity protein 1 (SP-1) binding site is necessary for TNF-alpha regulation. Electrophoretic mobility shift analysis demonstrated specific binding to this sequence, while site-directed mutagenesis of this site abrogated both JNK-mediated regulation as well as transcription factor binding. Expression of a dominant-negative SP-1 eliminated both the enhanced promoter activity and the elevated IP3R-mediated Ca2+ signals observed with TNF-alpha exposure. Overall, these data delineate a key pathway by which TNF-alpha in a neuronal environment modulates IP3R expression and intracellular Ca2+ homeostasis.