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.

项目总结/摘要 糖尿病是一种以胰岛素刺激的葡萄糖向骨骼肌的转运异常低下为特征的疾病， 肌肉是健康的主要威胁。AMPK的激活，例如通过运动、肌肉收缩或血清 饥饿提供了增加葡萄糖转运对胰岛素刺激的敏感性的手段。而 AS 160磷酸化的增强伴随着胰岛素敏感性的发展， 胰岛素刺激的葡萄糖转运增加的分子机制仍然未知。我们 旨在通过测试mTOR和ULK 1介导AMPK的假设来填补这一重要的知识空白- 诱导胰岛素敏感性。我们的初步数据表明，抑制mTOR复合物1（mTORC 1）会导致 胰岛素刺激葡萄糖转运增加。我们还发现，抑制ULK 1可以阻止胰岛素- 刺激血清饥饿肌管的葡萄糖摄取，而ULK 1的药理学激活剂增加 AS 160磷酸化。最后，我们的数据表明AMPK的激活导致mTORC 2活性的增加， 在肌管中，如mTORC 2底物Akt的磷酸化增加所证明的。来测试我们 假设，我们提出了三个具体目标。对于目标1，为了确定mTORC 1在胰岛素敏感性中的作用， 我们将检验抑制mTORC 1导致胰岛素敏感性增加并介导AMPK-1的假设。 诱导胰岛素敏感性。用于该目的的方法将包括确定是否通过抑制mTORC 1来抑制mTORC 1。 药理学和遗传学手段将增加胰岛素刺激的葡萄糖转运， mTORC 1通过生理学和遗传学手段将阻止胰岛素敏感性的发展， AMPK、血清饥饿或运动/肌肉收缩。对于目标2，确定ULK 1在胰岛素中的作用 敏感性，我们将测试ULK 1的激活足以增加胰岛素敏感性的假设， 这是AMPK诱导胰岛素敏感性所必需的。实现这一目标的方法将包括确定 ULK 1的药理学激活增加胰岛素刺激的葡萄糖转运， 药理学抑制ULK 1或ULK 1的失活或AMPK不敏感突变体的表达防止了 胰岛素敏感性的发展。对于目标3，为了确定mTORC 2在AS 160磷酸化和 胰岛素敏感性，我们将检验mTORC 2是AS 160磷酸化的重要介质的假设 在胰岛素敏感性的发展过程中。方法将包括确定药物或 mTORC 2复合物的遗传破坏将阻止AS 160磷酸化的正常增加， 血清饥饿、AMPK激活或运动/肌肉收缩，以及先前是否激活了 mTORC 2底物Akt引起胰岛素刺激的葡萄糖转运的后期增加。完成 具体的目标是阐明mTOR和ULK 1在控制骨骼肌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。