RENAL GLUCOSE TRANSPORT IN DIABETES

糖尿病中的肾脏葡萄糖转运

• 批准号: 3245036
• 负责人: Jesus H. Dominguez
• 金额: $ 12.11万
• 依托单位: INDIANA UNIV-PURDUE UNIV AT INDIANAPOLIS
• 依托单位国家: 美国
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-09-30 至 1995-09-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3245036
• 关键词: clearance rate; diabetic nephropathy; disease /disorder model; gel mobility shift assay; gene expression; genetic transcription; glucose transport; insulin; laboratory rat; membrane transport proteins; northern blottings; nuclear runoff assay; protein sequence; renal tubular transport; sodium; sodium potassium exchanging ATPase; transcription factor; western blottings

Most studies of diabetic nephropathy have not focused on the proximal tubule, although adaptations of this nephron segment to high glucose loads may cause tubular injury. In diabetes, hyperglycemia augments the filtered load of glucose to the tubule, and diminishes the tubule/glucose gradient necessary for facilitative glucose efflux. In vitro, Na+-dependent luminal influx (via Na+-GLUT) is decreased, although in vivo, the mass action effect derived from the high glucose load augments glucose influx. We propose to test the hypothesis that the proximal tubule maintains transtubular glucose flux by adaptations of the basolateral transporters (low Km GLUT 1 and high Km GLUT 2) at the level of gene transcription, resulting in depressed levels of GLUT 1 mRNA and protein, and increased levels of GLUT 2 mRNA and protein. This critical adaptation causes glucose to increase in the tubule due to the higher efflux Km of overexpressed GLUT 2. In this manner, the tubule/glucose gradient (the energy source for facilitative glucose efflux) is restored. However, the tubular glucose (and osmolar) load is increased, which may promote glucose flux through the polyol pathway. We plan to test the hypothesis with time course experiments using the streptozotocin diabetic rat model. We will evaluate the effect of glucose and insulin on the adaptation by measuring changes in GLUT 1 & MRNA, and protein plus GLUT activity in tubules from diabetic rats treated with insulin (lower glucose and higher insulin) and phlorizin (lower glucose and low insulin). The molecular mechanism of the adaptations will be assessed. The regulation of GLUT 1 & 2 gene transcription by tubular nuclear factors will be examined in diabetic rats, with the intent of identifying the trans acting factors responsible for the adaptation. To support the hypothesis, the role of glucose influx and Na+ flux will be examined: Na+ -GLUT mRNA and protein plus Na+ -GLUT function will be measured as a function of time. Moreover, since diabetes also increases Na+ influx in vivo, we will measure Na+ /K+ ATPase (alpha1) mRNA, Na+ pump number and activity. We believe that this information may prove valuable for the development of strategies to arrest diabetic nephropathy.

大多数糖尿病肾病研究并未关注近端肾病 肾小管，尽管该肾单位段适应高葡萄糖负荷 可能会导致肾小管损伤。 在糖尿病中，高血糖会增加滤过的 葡萄糖负载到小管，并减小小管/葡萄糖梯度 促进葡萄糖流出所必需的。 体外，Na+依赖性管腔 流入（通过 Na+-GLUT）减少，尽管在体内，质量作用 高葡萄糖负荷产生的效应会增加葡萄糖流入。 我们 提议检验近端小管维持的假设 基底外侧转运蛋白适应的跨管葡萄糖通量 （低 Km GLUT 1 和高 Km GLUT 2）在基因转录水平， 导致 GLUT 1 mRNA 和蛋白质水平降低，并增加 GLUT 2 mRNA 和蛋白质的水平。 这种关键的适应导致葡萄糖 由于过表达的 GLUT 的流出 Km 较高，导致肾小管增加 2. 通过这种方式，小管/葡萄糖梯度（能量来源） 促进葡萄糖流出）恢复。 然而，肾小管葡萄糖 （和渗透压）负荷增加，这可能会促进葡萄糖通过 多元醇途径。 我们计划用时间过程来检验假设 使用链脲佐菌素糖尿病大鼠模型进行的实验。 我们将评估 通过测量葡萄糖和胰岛素的变化来了解葡萄糖和胰岛素对适应的影响 糖尿病大鼠肾小管中的 GLUT 1 和 mRNA 以及蛋白质和 GLUT 活性 用胰岛素（较低的葡萄糖和较高的胰岛素）和根皮苷治疗 （降低血糖和低胰岛素）。 其分子机制 将评估适应性。 GLUT 1 & 2 基因的调控 将在糖尿病大鼠中检查肾小管核因子的转录， 目的是确定造成这种情况的反式作用因素 适应。 为了支持这一假设，葡萄糖流入和 Na+ 的作用 将检查流量：Na+ -GLUT mRNA 和蛋白质加上 Na+ -GLUT 功能 将作为时间的函数来测量。 此外，由于糖尿病还 增加体内 Na+ 流入，我们将测量 Na+ /K+ ATPase (alpha1) mRNA， Na+泵数量和活性。 我们相信这些信息可以证明 对于制定阻止糖尿病肾病的策略很有价值。