DYSREGULATION OF THE TAURINE TRANSPORTER IN DIABETES

糖尿病中牛磺酸转运蛋白的失调

• 批准号: 6381378
• 负责人: MARTIN J STEVENS
• 金额: $ 13.15万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-09-30 至 2003-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6381378
• 关键词: aldehyde reductase; cell osmotic pressure; diabetes mellitus genetics; gene expression; genetic regulation; genetic regulatory element; glucose metabolism; human tissue; hyperglycemia; membrane transport proteins; messenger RNA; oxidoreductase inhibitor; posttranscriptional RNA processing; posttranslational modifications; retinal pigment epithelium; taurine; tissue /cell culture

Chronic hyperglycemia has been implicated in the pathogenesis and progression of complications in diabetes although the underlying mechanisms remain uncertain. Interestingly, inhibitors of aldose reductase (AR) have been shown to ameliorate some of the complications of diabetes. For example they preserve nerve conduction velocity nerve blood flow and promote nerve regeneration in human and experimental diabetic neuropathy. AR catalyzes the conversion of glucose to sorbitol and is thought to act as an osmotic stress response protein by compensating for hypertonic stress through intracellular accumulation of sorbitol. In addition to this mechanism, other stress response proteins such as the NA-taurine co-transporter (TT) and the Na-myo- inositol co-transporter accumulate other osmolytes such as taurine and myo-inositol. In isotonic hyperglycemic stress, inappropriate sorbitol accumulation causes compensatory depletion of intracellular osmolytes such as taurine and myo-inositol, rendering them rate limiting for normal intracellular metabolism. This application focuses on the regulation of the human TT gene expression and function by glucose and osmotic stress mediated by AR- related and AR-unrelated mechanisms. The overall hypothesis is that glucose induces specific metabolically and/or osmotically mediated alterations in transcriptional, post-transcriptional and/or post- translational regulation of the hTT. As a model system, human retinal pigment epithelial cells (RPE) that vary in their degree of AR expression will be used in conjunction with AR inhibitors. This will allow to differentiate the osmotic from the metabolic effects of glucose. Three specific aims are proposed: (1) To characterize the glucose mediated AR-related and AR-unrelated changes in hTT mRNA abundance and correlate mRNA levels with peptide levels, activity and taurine content. (2) To determine whether changes in mRNA levels are due to changes in transcription or mRNA stability. (3) To determine the structure of the hTT gene and its 5' regulator region and identify cis elements that are necessary for glucose mediated changes in transcription and/or changes in mRNA stability. As an alternative, if in aim 1 little correlation between hTT mRNA abundance and hTT activity is found, then glucose mediated post-translational modifications will be examined.

慢性高血糖症与发病机制有关， 糖尿病并发症的进展，尽管潜在的 机制仍然不确定。 有趣的是， 还原酶（AR）已被证明可以改善某些并发症 糖尿病 例如，它们保留了神经传导速度， 促进人体和实验性神经再生 糖尿病神经病变 AR催化葡萄糖转化为山梨醇 并被认为作为渗透应激反应蛋白， 通过细胞内积累补偿高渗应激 山梨醇。除了这种机制，其他应激反应 蛋白质，如NA-牛磺酸共转运蛋白（TT）和Na-肌- 肌醇共转运蛋白积累其它渗透物如牛磺酸， 肌醇。 在等渗高血糖应激中， 蓄积引起细胞内渗透调节物质的代偿性消耗 如牛磺酸和肌醇，使它们成为心率限制 正常的细胞内代谢 本申请集中于人TT基因的调控 表达和功能的葡萄糖和渗透应激介导的AR- 相关和不相关的机制。 总的假设是， 葡萄糖诱导特异性代谢和/或代谢介导的 转录、转录后和/或转录后的改变 hTT的翻译调控。 作为模型系统， 色素上皮细胞（RPE），其AR程度不同 表达将与AR抑制剂联合使用。 这将 允许区分渗透和代谢效应， 葡萄糖 提出了三个具体目标：（1）表征 葡萄糖介导的AR相关和AR无关的hTT mRNA变化 丰度和相关的mRNA水平与肽水平，活性和 牛磺酸含量 (2)为了确定mRNA水平的变化是否是 由于转录或mRNA稳定性的变化。 (3)确定 hTT基因及其5'调控区的结构和鉴定顺式 葡萄糖介导的变化所必需的元素， 转录和/或mRNA稳定性的变化。 作为替代方案，如果 在目标1中，hTT mRNA丰度和hTT活性之间几乎没有相关性 发现，那么葡萄糖介导的翻译后修饰将 接受检查。