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Skeletal Muscle Glucose Uptake: Exercise and Insulin

骨骼肌葡萄糖摄取：运动和胰岛素

基本信息

批准号：
9921359
负责人：
Gregory D. Cartee
金额：
$ 52.15万
依托单位：
UNIVERSITY OF MICHIGAN AT ANN ARBOR
依托单位国家：
美国
项目类别：
财政年份：
2006
资助国家：
美国
起止时间：
2006-07-01 至 2022-04-30
项目状态：
已结题

项目摘要

Increased post-exercise insulin sensitivity in skeletal muscle is a well-known health benefit of acute exercise, but the underlying mechanisms remain uncertain. The long-range goal is to fully understand the cellular events responsible for this major health benefit. Skeletal muscle is a heterogenous tissue comprised of multiple fiber types with diverse metabolic phenotypes. Conventional tissue analysis cannot discern cellular mechanisms, but a recently developed and validated method enables determination of glucose uptake (GU) and fiber type in single muscle fibers. Recent research using this approach has uncovered striking and unexpected fiber type- selective exercise effects in normal and insulin resistant muscle that were not attributable to lack of recruitment of the fiber types that failed to attain exercise-induced improvement in insulin sensitivity. Akt Substrate of 160 kDa (AS160) is a key insulin signaling protein that regulates GLUT4 glucose transporter translocation. Greater AS160 phosphorylation is consistently linked to greater insulin-mediated GU in whole muscles from normal and insulin-resistant rats. In addition to determination of single fiber GU, this project will use novel methods to measure, for the first time, exercise effects on cellular insulin signaling (including AS160 phosphorylation) and cell surface GLUT4 levels in specific fiber types, thereby advancing understanding from the level of whole muscles to the cellular level of specific fiber types. Newly created AS160-null rats with AAV vector-mediated wildtype or phosphomutated AS160 expression will be used to reveal if AS160 expression or phosphorylation is essential for greater insulin-mediated GU post-exercise in whole muscles and specific fiber types of normal and insulin resistant rats. These unique approaches will make possible unprecedented evaluation of cellular events responsible for the post-exercise increase in insulin sensitivity. The Specific Aims are: 1) To elucidate mechanisms for the exercise-induced improvement in insulin-stimulated GU of whole muscles and specific fiber types from normal rats; 2) To test the mechanisms for high fat diet (HFD)-induced insulin resistance in whole muscles and specific fiber types; and 3) To test the mechanisms for exercise-induced improvement in insulin-stimulated GU of whole muscles and specific fiber types from high fat diet-induced insulin resistant rats. The predicted results are that in whole muscles and fiber types with enhanced insulin-mediated GU after exercise by normal and insulin resistant rats of both sexes, γ3-AMP-activated protein kinase (AMPK) stimulation immediately post-exercise is a trigger that catalyzes greater phosphorylation of AS160 Ser704 (AMPK phosphosite) which acts as a memory element favoring greater insulin-induced AS160 phosphorylation on Thr642 and Ser588, mediators for greater cell surface GLUT4, the end-effector enabling greater insulin- mediated GU post-exercise. We also predict AS160 expression and site-selective phosphorylation are essential for exercise effects on insulin-mediated GU in normal and insulin resistant muscle. This research will provide groundbreaking insights into cellular mechanisms underlying improved insulin sensitivity post-exercise.

运动后骨骼肌对胰岛素的敏感性增加是众所周知的急性运动对健康的好处，但潜在的机制仍不确定。长期的目标是完全理解细胞事件为这一重大的健康福利负责。骨骼肌是由多种纤维组成的异质组织代谢表型多样的类型。传统的组织分析无法辨别细胞机制，但最近开发和验证的一种方法可以确定患者的葡萄糖摄取(GU)和纤维类型单一的肌肉纤维。最近使用这种方法的研究发现了惊人的和意想不到的纤维类型- 正常肌肉和胰岛素抵抗肌肉中的选择性运动效应不是由于缺乏招募在运动诱导的胰岛素敏感性改善失败的纤维类型中。AKT基板160 KDA(AS160)是一种关键的胰岛素信号蛋白，调节GLUT4葡萄糖转运蛋白的转运。更大 AS160的磷酸化与更多的胰岛素介导的GU在正常和胰岛素抵抗的大鼠。除了单纤维GU的测定外，该项目还将使用新的方法来首次测量运动对细胞胰岛素信号的影响(包括AS160磷酸化)和细胞表面GLUT4在特定纤维类型中的水平，从而从整体水平上促进理解肌肉到细胞水平的特定纤维类型。AAV载体介导法建立新的AS160缺失大鼠野生型或磷酸化的AS160表达将被用来揭示AS160的表达或磷酸化是运动后整体肌肉和特定纤维类型中胰岛素介导的GU增加所必需的和胰岛素抵抗的大鼠。这些独特的方法将使前所未有的细胞评估成为可能导致运动后胰岛素敏感性增加的事件。具体目的是：1)澄清运动改善胰岛素刺激的全肌和特异性GU的机制 2)探讨高脂饮食(HFD)诱导大鼠胰岛素抵抗的机制。整个肌肉和特定的纤维类型；以及3)测试运动诱导的改善胰岛素刺激高脂饮食诱导的胰岛素抵抗大鼠全肌和特定纤维类型的GU。预测结果是，在胰岛素介导的GU增强后，整个肌肉和纤维型正常大鼠和胰岛素抵抗大鼠运动后γ-3-AMPK活性的变化运动后即刻的刺激是催化AS160Ser704更大程度磷酸化的触发因素 (AMPK亚磷酸盐)，它是一种记忆元件，有利于胰岛素诱导更大的AS160磷酸化在Thr642和Ser588上，更大细胞表面GLUT4的介体，使更多胰岛素的终端效应- 运动后介导的GU。我们还预测AS160的表达和位点选择性磷酸化是运动对正常肌肉和胰岛素抵抗肌肉中胰岛素介导的GU的影响是必不可少的。这项研究将对运动后胰岛素敏感性改善背后的细胞机制提供开创性的见解。