Skeletal Muscle Glucose Transport: Exercise and Insulin

骨骼肌葡萄糖转运：运动和胰岛素

• 批准号: 8775661
• 负责人: Gregory D. Cartee
• 金额: $ 34.78万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-07-01 至 2016-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8775661
• 关键词: Accounting; Attenuated; Blood Glucose; Catalytic Domain; Complex; Data; Defect; Development; Diabetes Mellitus; Distal; Dose; Epidemic; Exercise; Fiber; Funding; GLUT4 gene; GTPase-Activating Proteins; Gene Transfer; Goals; Health; Health Benefit; Human; Individual; Insulin; Insulin Resistance; Learning; Link; Lipids; MAPK8 gene; Measures; Mediating; Mediator of activation protein; Methods; Muscle; Muscle Fibers; Non-Insulin-Dependent Diabetes Mellitus; Obesity; Phosphorylation; Phosphotransferases; Physiological; Post-Translational Protein Processing; Protein Dephosphorylation; Protein Isoforms; Protein S; Protein phosphatase; Public Health; Publications; Rattus; Regulation; Reporting; Research; Role; Secondary to; Signal Transduction; Site; Skeletal Muscle; Substrate Specificity; Testing; genetic approach; glucose disposal; glucose transport; glucose uptake; human NOS2A protein; improved; in vivo; inhibitor/antagonist; innovation; insight; insulin sensitivity; insulin signaling; novel; prevent; protein phosphatase 2A regulatory subunit 65 kDa; rab GTP-Binding Proteins; research study; sedentary

DESCRIPTION (provided by applicant): Increased post-exercise (PEX) insulin sensitivity, first demonstrated in 1982, is among the best documented exercise benefits linked to improved health, but identification of the mechanism has been elusive. Exercise by lean, normal individuals has little effect on proximal insulin signaling, suggesting exercise alters a distal site. Progress stalled until the discovery of a sustained PEX increase in the most distal signaling step known to be crucial for glucose transport (GT): phosphorylation of Akt Substrate of 160 kDa (AS160). The sustained PEX increase in phosphorylated AS160 (pAS160) tracks closely with elevated insulin-induced GT in lean rats, and sustained pAS160 is also found in muscle of lean humans PEX. Increased pAS160 has emerged as an attractive candidate to explain improved insulin sensitivity PEX. The broad, long-term goal is to fully elucidate the mechanisms that underlie enhanced insulin sensitivity PEX. The 3 Specific Aims are: 1) Identify the mechanism for the sustained increase in AS160 phosphorylation in skeletal muscle of lean rats after exercise. 2) By expressing in rat skeletal muscle AS160 that is genetically modified to prevent phosphorylation on key sites, determine AS160's role in exercise-induced changes in GT in lean rats. 3) Identify the similarities and differences between lean and obese rats in the specific mechanisms for their respective exercise-induced improvements in insulin-stimulated GT. Evidence indicates the sustained PEX increase in pAS160 is not attributable to persistent activation of kinases. A novel idea to be tested is that the sustained elevation in pAS160 is because of attenuated AS160 dephosphorylation by Ser/Thr protein phosphatases. Because preliminary data implicate protein phosphatase 2A (PP2A) in AS160 dephosphorylation, multiple approaches will be used for Aim 1 to probe PP2A's regulation of pAS160. Aim 2 will use an innovative method to measure GT by single muscle fibers that are matched for fiber type, but differ by expression of wildtype AS160 or AS160 genetically modified to prevent phosphorylation on key sites to learn if the improved PEX insulin-mediated GT in lean rats is attributable to greater pAS160. Aim 3 will determine if the well-known exercise benefits on insulin sensitivity for lean and obese rats are accrued by distinct mechanisms. Exercise by obese rats is predicted to reduce high muscle levels of mediators of insulin resistance (inducible nitric oxide synthase; protein S- nitrosylation; lipid metabolites; JNK, IKK & PKC? activation) leading to enhanced insulin signaling and GT. However, in muscles from lean rats, exercise is predicted to not greatly alter their already low levels of mediators or normal levels of proximal insulin signaling. The sustained increase in pAS160 PEX observed in lean humans was reported to be less in obese people. Accordingly, experiments will be performed to test if the greater PEX insulin-mediated GT previously found for lean vs. obese rats is attributable to greater pAS160 PEX in lean rats. Completion of the proposed research will provide novel insights into the specific mechanisms that account for improved insulin sensitivity, a major health benefit for both lean and obese individuals.

描述（由申请人提供）：1982年首次证明的运动后（PEX）胰岛素敏感性增加，是与改善健康有关的最佳记载的运动益处之一，但该机制的识别是难以捉摸的。通过精益锻炼，正常人对近端胰岛素信号的影响很小，这表明运动改变了远端部位。进步停滞不前，直到发现最远端信号传导步骤的持续PEX增加，已知对于葡萄糖转运至关重要（GT）：Akt底物的磷酸化为160 kDa（AS160）。在瘦大鼠中，胰岛素诱导的GT升高，磷酸化的AS160（PAS160）的持续PEX持续增加，并且在瘦肉人类PEX的肌肉中也发现了持续的PAS160。 PAS160的增加已成为解释改善胰岛素敏感性PEX的有吸引力的候选者。广泛的长期目标是充分阐明胰岛素敏感性PEX的基础的机制。 3个具体目的是：1）确定运动后瘦大鼠骨骼肌AS160磷酸化持续增加的机制。 2）通过在大鼠骨骼肌AS160中表达经过遗传修饰以防止关键部位磷酸化的大鼠骨骼肌AS160，请确定AS160在运动诱导的瘦大鼠GT变化中的作用。 3）确定瘦大鼠和肥胖大鼠在特定机制中的相似性和差异，以促进其各自的运动引起的胰岛素刺激的GT的改善。证据表明，PAS160的PEX持续增加并不归因于激酶的持续激活。要测试的一个新颖的想法是，PAS160中的持续升高是由于Ser/Thr蛋白磷酸酶通过Ser/Thr蛋白磷酸酶的AS160去磷酸化减弱。由于初步数据暗示AS160去磷酸化中的蛋白质磷酸酶2a（PP2A），因此将使用多种方法用于AIM 1来探测PP2A对PAS160的调节。 AIM 2将使用一种创新的方法来测量与纤维类型相匹配的单个肌肉纤维的GT，但由于野生型AS160或AS160的表达而有所不同，以防止在关键部位进行磷酸化以防止磷酸化的磷酸化，以了解较大的PEX胰岛素介导的瘦大鼠是否可以归因于PAS160。 AIM 3将确定众所周知的运动对胰岛素敏感性对瘦和肥胖大鼠的敏感性是否受到不同的机制的影响。预计肥胖大鼠的运动将降低胰岛素抵抗的介质的高肌肉水平（诱导一氧化氮合酶；蛋白质s-亚硝基化；脂质代谢物； JNK，IKK＆PKC？激活），导致胰岛素信号和GT增强。但是，在瘦大鼠的肌肉中，预计运动不会极大地改变其已经较低水平的介体或正常水平的近端胰岛素信号传导。据报道，肥胖人中观察到的PAS160 PEX的持续增加在肥胖者中较少。因此，将进行实验，以测试是否在瘦大鼠中发现较大的PEX胰岛素介导的GT是否归因于较大的PAS160 PEX。拟议研究的完成将提供对提高胰岛素敏感性的特定机制的新见解，这对精益和肥胖个体都是主要的健康益处。