Cytokine-Mediated Regulation of Cholesterogenesis

细胞因子介导的胆固醇生成调节

• 批准号: 6430095
• 负责人: ISHAIAHU SHECHTER
• 金额: $ 33.46万
• 依托单位: HENRY M. JACKSON FDN FOR THE ADV MIL/MED
• 依托单位国家: 美国
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-06-01 至 2006-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6430095
• 关键词: alkyltransferase; biological signal transduction; cholesterol; clinical research; cytokine; enzyme activity; genetic transcription; hamsters; interleukin 1; lipopolysaccharides; messenger RNA; phosphorylation; posttranslational modifications; protein degradation; protein localization; squalene; steroid biosynthesis; tissue /cell culture; transcription factor; tumor necrosis factor alpha

DESCRIPTION (provided by applicant): Squalene synthase (SQS) catalyzes the first reaction of the isoprenoid metabolic pathway committed to cholesterol biosynthesis and its activity regulates the flux of intermediates to sterols. SQS is regulated by sterols, lipopolysaccharide (LPS), and the pro-inflammatory cytokines tumor necrosis factor-alpha (TNF-alpha) and interlukin-1-beta (IL-1-beta). Sterol-mediated transcriptional regulation of SQS is well understood, but little is known about the mechanism of its regulation during the inflammatory response. We propose to test the hypothesis that LPS and cytokines regulate SQS mRNA transcription and stability and enzyme protein posttranslational modification, stability and subcellular localization. In Specific Aim 1 we will determine the effects of LPS and cytokines on hepatic SQS transcription and mRNA stability in Syrian hamsters fed with different cholesterogenic diets. We will also determine changes in SQS mRNA level and size during response to cytokines and the contribution of the specific cytokines to these processes. In Specific Aim 2 we propose to elucidate the molecular mechanisms responsible for SQS mRNA regulation by LPS and cytokines. This will be achieved, in cultured cells, by examining promoter sequence elements responsible for the transcriptional repression by cytokines, by identification of transcription factors involved in this suppression, and by the elucidation of cellular signaling pathways involved in the transcriptional regulation. In addition, sequences required for SQS mRNA destabilization by cytokines will be localized. In Specific Aim 3 we propose to elucidate the LPS-and cytokine-induced, post-translational mechanisms underlying the decrease in SQS enzymic activity. We will examine SQS protein destabilization, mechanisms for its degradation, post-translational modification by phosphorylation, and change in its subcellular localization in response to LPS and cytokines. Achievement of the three Specific Aims will contribute directly to our long-term goal to elucidate the importance of SQS regulation on isoprenoid metabolic flux. It will increase our understanding of sterol metabolism in acute phase response (APR) to infection and inflammation and the role of SQS regulation in this process. Finally, it will enhance our overall understanding of hepatic cholesterol production in normal and pathological situations.

描述（由申请人提供）：Sperenene合酶（SQS）催化 原代代谢途径的第一反应致力于胆固醇 生物合成及其活性调节中间体向固醇的通量。 SQS受固醇，脂多糖（LPS）和促炎性的调节 细胞因子肿瘤坏死因子-Alpha（TNF-Alpha）和Interlukin-1-beta （IL-1-β）。固醇介导的SQS的转录调控很好 理解，但对其在调节过程中的机制知之甚少 炎症反应。我们建议检验LP和 细胞因子调节SQS mRNA转录和稳定性以及酶蛋白 翻译后修饰，稳定性和亚细胞定位。在 具体目的1我们将确定LP和细胞因子对肝的影响 叙利亚仓鼠的SQS转录和mRNA稳定性 胆固性饮食。我们还将确定SQS mRNA水平的变化和 对细胞因子的反应和特定的贡献的大小 这些过程的细胞因子。在特定目标2中，我们建议阐明 由LP和细胞因子调节SQS mRNA的分子机制。 通过检查启动子序列，将在培养的细胞中实现这一点 负责细胞因子转录抑制的要素， 鉴定该抑制所涉及的转录因子，并通过 阐明涉及转录的细胞信号通路 规定。此外，SQS mRNA不稳定所需的序列 细胞因子将被定位。在特定目标3中，我们建议阐明唱片，并 细胞因子诱导的，翻译后机制的下降是基础的 SQS酶活性。我们将检查SQS蛋白质不稳定，机制 为了降解，通过磷酸化后翻译后修饰，并 响应LP和细胞因子的亚细胞定位变化。 实现这三个特定目标将直接为我们的 长期目标是阐明SQS调节对异丙的重要性 代谢通量。它将增加我们对固醇代谢的理解 急性相反应（APR）对感染和炎症以及SQ的作用 在此过程中的监管。最后，它将增强我们的整体理解 在正常和病理情况下产生肝胆固醇的。