Insulin sensitivity in skeletal muscle

骨骼肌的胰岛素敏感性

• 批准号: 10439090
• 负责人: JONATHAN S. FISHER
• 金额: $ 37.88万
• 依托单位: SAINT LOUIS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-04-01 至 2025-03-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10439090
• 关键词: 5' -AMP-activated protein kinase; Affect; Alleles; American; Antidiabetic Drugs; Blood Glucose; Characteristics; Complex; Data; Development; Diabetes Mellitus; Dominant-Negative Mutation; Effectiveness; Exercise; Exposure to; FRAP1 gene; Future; Genetic; Glucose; Health; Insulin; Insulin Resistance; Knowledge; Mediating; Mediator of activation protein; Molecular; Mus; Muscle; Muscle Contraction; Muscle Fibers; Persons; Pharmacology; Phosphorylation; Physiological; Protein Kinase; Proteins; Raptors; Role; Serum; Sirolimus; Skeletal Muscle; Starvation; TSC2 gene; Testing; Therapeutic; United States; Work; base; glucose transport; glucose uptake; inhibitor; insulin regulation; insulin sensitivity; insulin sensitizing drugs; knock-down; mTOR inhibition; mutant; novel; prevent; sugar; uptake

Project Summary/Abstract Diabetes, a condition characterized by abnormally low insulin-stimulated glucose transport into skeletal muscle, is a major threat to health. Activation of AMPK, such as by exercise, muscle contractions, or serum starvation, provides a means to increase sensitivity of glucose transport to stimulation by insulin. While enhanced phosphorylation of AS160 occurs concomitant with development of insulin sensitivity, the complete molecular mechanisms underlying the increase in insulin-stimulated glucose transport remain unknown. We aim to fill this important knowledge gap by testing the hypothesis that mTOR and ULK1 mediate AMPK- induced insulin sensitivity. Our preliminary data show that inhibition of mTOR complex 1 (mTORC1) causes an increase in insulin-stimulated glucose transport. We have also found that inhibition of ULK1 prevents insulin- stimulated glucose uptake by serum-starved myotubes, while a pharmacological activator of ULK1 increases AS160 phosphorylation. Finally, our data show that activation of AMPK causes an increase in mTORC2 activity in myotubes, as demonstrated by increased phosphorylation of the mTORC2 substrate Akt. To test our hypotheses, we propose three specific aims. For Aim 1, to determine the role of mTORC1 in insulin sensitivity, we will test the hypothesis that inhibition of mTORC1 causes increased insulin sensitivity and mediates AMPK- induced insulin sensitivity. Approaches for this aim will include determining whether inhibition of mTORC1 by pharmacological and genetic means will increase insulin-stimulated glucose transport and whether activation of mTORC1 by physiological and genetic means will prevent development of insulin sensitivity after activation of AMPK, serum starvation, or exercise/muscle contractions. For Aim 2, to determine the role of ULK1 in insulin sensitivity, we will test the hypothesis that activation of ULK1 is sufficient to increase insulin sensitivity and necessary to induction of insulin sensitivity by AMPK. Approaches to this aim will include determining whether pharmacological activation of ULK1 increases insulin-stimulated glucose transport and whether pharmacological inhibition of ULK1 or expression of inactive or AMPK-insensitive mutants of ULK1 prevent development of insulin sensitivity. For Aim 3, to determine the role of mTORC2 in AS160 phosphorylation and insulin sensitivity, we will test the hypothesis that mTORC2 is an important mediator of AS160 phosphorylation during development of insulin sensitivity. Approaches will include determining whether pharmacological or genetic disruption of the mTORC2 complex will prevent the normal increase in AS160 phosphorylation after serum starvation, activation of AMPK, or exercise/muscle contractions and whether prior activation of the mTORC2 substrate Akt causes a later increase in insulin-stimulated glucose transport. Completion of the specific aims will elucidate novel roles of mTOR and ULK1 in control of insulin sensitivity in skeletal muscle and suggest future strategies to overcome insulin resistance.

项目摘要/摘要 糖尿病，这种疾病以异常低胰岛素刺激的葡萄糖转运到骨骼为特征 肌肉是对健康的主要威胁。激活AMPK，例如运动，肌肉收缩或血清 饥饿，提供了一种增加葡萄糖转运对胰岛素刺激的敏感性的方法。尽管 AS160的磷酸化增强与胰岛素敏感性的发展同时发生，完整 胰岛素刺激的葡萄糖转运增加的分子机制尚不清楚。我们 旨在通过检验MTOR和ULK1介导AMPK-的假设来填补这一重要的知识差距。 诱导胰岛素敏感性。我们的初步数据表明，抑制MTOR复合物1（MTORC1）导致 增加胰岛素刺激的葡萄糖转运。我们还发现，抑制ULK1可防止胰岛素 - 血清饥饿的肌管刺激葡萄糖摄取，而ULK1的药理学激活剂增加 AS160磷酸化。最后，我们的数据表明，AMPK的激活导致MTORC2活性增加 在肌管中，MTORC2底物AKT的磷酸化增加所证明。测试我们的 假设，我们提出了三个具体目标。对于AIM 1，确定MTORC1在胰岛素敏感性中的作用， 我们将检验以下假设：MTORC1抑制会导致胰岛素敏感性提高并介导AMPK- 诱导胰岛素敏感性。此目的的方法将包括确定是否抑制MTORC1 药理和遗传手段将增加胰岛素刺激的葡萄糖转运，以及是否激活 MTORC1通过生理和遗传手段将阻止激活后胰岛素敏感性的发展 AMPK，血清饥饿或运动/肌肉收缩。对于AIM 2，确定ULK1在胰岛素中的作用 灵敏度，我们将检验以下假设：ULK1的激活足以提高胰岛素敏感性和 AMPK诱导胰岛素敏感性所必需的。实现此目标的方法将包括确定是否 ULK1的药理激活增加了胰岛素刺激的葡萄糖转运以及是否是否 ULK1的药理学抑制或ULK1的无活性或不敏感突变体的表达预防 胰岛素敏感性的发展。对于AIM 3，确定MTORC2在AS160磷酸化和 胰岛素敏感性，我们将检验以下假设：MTORC2是AS160磷酸化的重要介体 在胰岛素敏感性的发展过程中。方法将包括确定药理学还是 MTORC2复合物的遗传破坏将阻止AS160磷酸化的正常增加 血清饥饿，AMPK的激活或运动/肌肉收缩以及是否事先激活 MTORC2底物AKT会导致胰岛素刺激的葡萄糖转运的增加。完成 具体目的将阐明MTOR和ULK1在控制骨骼肌中胰岛素敏感性中的新作用 并提出未来克服胰岛素抵抗的策略。