GLUCOSE TOXICITY IN SKELETAL MUSCLE

骨骼肌中的葡萄糖毒性

• 批准号: 2151383
• 负责人: MIKE M MUECKLER
• 金额: $ 19.52万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-08-01 至 1999-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2151383
• 关键词: carbohydrate metabolism; gene induction /repression; genetically modified animals; glucosamine; glucose; glucose transporter; hyperglycemia; immunoelectron microscopy; insulin; insulin sensitivity /resistance; laboratory mouse; muscle contraction; sarcolemma; striated muscles; transferase

The hyperglycemia associated with diabetes exacerbates insulin resistance via a direct toxic effect of glucose on skeletal muscle. This in turn contributes to the worsening of glycemic control and the development of morbidity. The mechanism by which glucose exerts a toxic effect on skeletal muscle is unknown, but the end result is decreased sensitivity of the muscle Glut4 glucose transporter to insulin. A line of transgenic mice has been developed in which the constitutive Glut1 glucose transporter is overexpressed specifically in skeletal muscle. Basal glucose transport is dramatically elevated in the muscle of these mice via the constitutive overexpression of Glut1 in the sarcolemma. The increased basal flux of glucose into muscle mimics the effect of hyperglycemia and results in the desensitization of Glut4. These mice provide a unique model system for studying the direct effects of muscle glucose toxicity in vivo in the absence of secondary effects due to hyperglycemia and altered circulating insulin levels. Recent evidence suggests that increased flux of glucose through the glucosamine metabolic pathway may be responsible for glucose- induced insulin resistance in skeletal muscle. The long-term goal of this project is to exploit this transgenic mouse model to help elucidate the mechanism of glucose-induced insulin resistance in skeletal muscle. To accomplish this goal, we propose the following specific aims: l. To determine whether insulin and contraction-induced translocation of Glut4 to the plasma membrane are defective in the muscle of Glut1 transgenic mice using quantitative immunogold electron microscopy. 2. To determine how elevation of intracellular free glucose in vivo affects the pattern of skeletal muscle gene expression and to identify novel genes that may contribute to glucose toxicity. This will be accomplished by the use of reverse transcription differential mRNA display analysis of the Glut1 transgenic skeletal muscle. 3. To determine whether altered glucosamine metabolism is involved in the defect in Glut4 activation in the Glut1 transgenic mice. This will be explored by investigating the direct effect of glucosamine on Glut4 translocation in muscle, measuring levels of glucosamine metabolites in muscle of Glut1 transgenic mice, and examining the effect of glucosamine on the expression of glucose-regulated candidate genes identified in specific aim #2. Transgenic mice overexpressing glutamine:fructose-6- phosphate amidotransferase in muscle will be generated and characterized in order to directly test the hypothesis that increased glucosamine metabolism is responsible for glucose-induced insulin resistance in skeletal muscle.

与糖尿病有关的高血糖加剧了胰岛素抵抗 通过葡萄糖对骨骼肌的直接毒性作用。反过来 有助于血糖控制的恶化和发展 发病率。葡萄糖对 骨骼肌是未知的，但最终结果是降低的灵敏度 肌肉Glut4葡萄​​糖转运蛋白到胰岛素。一系列转基因小鼠 已经开发了构型Glut1葡萄糖转运蛋白是 在骨骼肌中专门表达过表达。基底葡萄糖的传输是 这些小鼠的肌肉在肌肉中大幅升高 肌膜中Glut1的过表达。增加的基础通量 葡萄糖成肌肉模仿高血糖的作用，并导致 GLUT4的脱敏。这些小鼠为 研究体内肌肉葡萄糖毒性在体内的直接影响 由于高血糖和循环改变而没有次要作用 胰岛素水平。最近的证据表明葡萄糖的通量增加 通过葡萄糖代谢途径可能是葡萄糖 - 在骨骼肌中诱导胰岛素抵抗。这个长期目标 项目将利用这种转基因鼠标模型，以帮助阐明 葡萄糖诱导的胰岛素耐药性机理。到 实现这一目标，我们提出以下具体目标： l。确定胰岛素和收缩引起的易位 GLUT4到质膜在Glut1的肌肉中有缺陷 使用定量免疫元电子显微镜的转基因小鼠。 2。确定体内细胞内游离葡萄糖的升高 影响骨骼肌基因表达的模式，并确定 可能导致葡萄糖毒性的新型基因。这将是 通过使用逆转录差异mRNA显示来完成 GLUT1转基因骨骼肌的分析。 3。确定葡萄糖代谢是否涉及改变 GLUT1转基因小鼠的GLUT4激活缺陷。这将是 通过研究葡萄糖对GLUT4的直接影响探索 肌肉的易位，测量葡萄糖代谢物的水平 GLUT1转基因小鼠的肌肉，并检查葡萄糖的作用 关于在葡萄糖调节的候选基因的表达 特定目标＃2。过表达谷氨酰胺的转基因小鼠：果糖-6- 将产生并表征肌肉中的磷酸盐酰胺转移酶 为了直接检验葡萄糖增加的假设 代谢负责葡萄糖诱导的胰岛素抵抗 骨骼肌。