Ang II and Overnutrition and Insulin resistance in Cardiovascular Tissue

血管紧张素II与心血管组织营养过剩和胰岛素抵抗

• 批准号: 8087391
• 负责人: James Russell Sowers
• 金额: $ 36.96万
• 依托单位: UNIVERSITY OF MISSOURI-COLUMBIA
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-04-11 至 2016-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8087391
• 关键词: 1-Phosphatidylinositol 3-Kinase; Address; Adult; American; Angiotensin II; Animals; Attenuated; Binding; Biological; Blood Glucose; Blood Pressure; Blood Vessels; Blood flow; C57BL/6 Mouse; Carbohydrates; Cardiac; Cardiac Myocytes; Cardiovascular Diseases; Cardiovascular Physiology; Cardiovascular system; Cells; Chronic; Comorbidity; Coronary; Data; Development; Diabetes Mellitus; Diet; Dietary Fats; Dietary Sucrose; Disease; Docking; Dose; Endothelial Cells; Euglycemic Clamping; Event; Exposure to; Fatty acid glycerol esters; Functional disorder; Glucose; Glucose Clamp; Hormones; Hypertension; Image; Imaging Device; Impairment; In Vitro; Inflammation; Insulin; Insulin Receptor; Insulin Resistance; Intake; Knock-out; Laboratories; Lead; Link; Liver; Mass Spectrum Analysis; Measures; Mediating; Metabolic; Modeling; Molecular; Mus; Myocardial; Myocardium; Nitric Oxide; Non-Insulin-Dependent Diabetes Mellitus; Nutrient; Obesity; Overnutrition; Overweight; Pathway interactions; Persons; Phosphorylation; Phosphotransferases; Positron-Emission Tomography; Prevalence; Production; Protein-Serine-Threonine Kinases; Proteins; Proto-Oncogene Proteins c-akt; Receptor Inhibition; Receptor, Angiotensin, Type 1; Relaxation; Renin-Angiotensin System; Research; Resistance; Ribosomal Protein S6 Kinase; Rodent; Rodent Model; Role; Serine; Signal Pathway; Signal Transduction; Site; Skeletal Muscle; Small Interfering RNA; Smooth Muscle Myocytes; Sucrose; Telemetry; Tissues; Tyrosine; Vascular Endothelial Cell; Vasodilation; Western Blotting; Work; animal tissue; cohort; db/db mouse; glucose metabolism; glucose transport; glucose uptake; in vivo; innovation; insulin receptor substrate 1 protein; insulin sensitivity; insulin signaling; mTOR protein; novel; nutrition; olmesartan; prevent; receptor; response; sensor; skeletal; therapeutic target

DESCRIPTION (provided by applicant): Diminished insulin (INS) sensitivity is a common feature of disease states such as obesity, hypertension and diabetes. Over-nutrition (especially that characterized by excess intake of fat and carbohydrates) is a major factor in the increased prevalence of hypertension and diabetes. These co-morbidities may be driven by a decrease in INS-mediated vasorelaxation and glucose transport in cardiovascular (CV) and skeletal muscle tissue. In addition to over-nutrition, several other mechanisms, such as enhanced activation of the renin- angiotensin-system (RAS), inflammation, and associated abnormalities in INS metabolic signaling, may help explain the linkage between INS resistance and hypertension. There is emerging evidence that over-nutrition and angiotensin II (ANG II) may promote INS resistance through the mammalian target of rapamycin (mTOR)/S6 kinase 1 (S6K1) signaling pathway. mTOR, a highly conserved nutrient sensor, modulates INS metabolic signaling through its phosphorylation (P) of S6K1, an evolutionarily conserved serine (Ser) kinase. Evidence is mounting that chronic activation of S6K1, by excessive nutrients, promotes INS resistance in fat, liver and skeletal muscle tissue through increased Ser (P) of the critical INS signaling/docking molecule, INS receptor substrate protein 1 (IRS-1), leading to impaired phosphoinositol 3 kinase (PI3-K) engagement and protein kinase B (Akt) stimulation. Our recent work indicates that S6K1 is activated by ANG II in CV tissue leading to diminished INS metabolic signaling and biological consequences, such as impaired nitric oxide (NO)-mediated vascular relaxation. This proposal seeks to investigate novel molecular mechanisms by which ANG II and over-nutrition individually and collectively promote INS resistance in CV and skeletal muscle tissue. To evaluate the CV functional effects of INS metabolic signaling, we will utilize our state of the art rodent imaging center. In the INS resistant state, myocardial and skeletal muscle glucose uptake and metabolism is impaired, leading to diastolic dysfunction, attenuated myocardial and skeletal muscle blood flow, and impaired ischemic reconditioning. We have shown that both impaired INS stimulated glucose uptake and diastolic dysfunction are related to impaired systemic and myocardial INS metabolic signaling in models of obesity and increased tissue RAS expression. For this proposal, we will utilize novel knockout and knockdown strategies, as well as innovative rodent imaging tools, to evaluate the impact of increased S6K1 signaling (ANG II and/or excess nutrients) on myocardial function and coronary and skeletal microvascular blood flow responses to INS metabolic signaling. To address Aim 1, we will examine the relationship between ANG II and S6K1 activation and INS signaling in primary cultured endothelial cells, vascular smooth muscle cells and cardiomyocytes. Metabolic signaling results will be correlated to functional measures including NO production, cardiomyocyte glucose transport and diastolic relaxation. To further explore the collective, as well as the independent, roles of ANG II and over-nutrition on S6K1, Aim 2 will focus on in vivo/ex vivo effects in the S6K1-/- and C57BL/6 mice treated with ANG II that produces a slow pressor response and/or a high fat (60%) and high sucrose (20%) diet. A cohort of animals will be treated with an AT1R blocker (olmesartan) at a dose of 0.5 mg/kg/day, a dose determined by telemetry to have no effect on blood pressure in db/db mice. INS resistance will be assessed by hyperinsulinemic, euglycemic clamp, cardiac PET scanning, ex vivo IRS-1 (P) and INS metabolic signaling, and glucose uptake in heart and skeletal muscle. Finally, in vivo INS mediated skeletal muscle arteriolar and ex vivo coronary arteriolar, NO induced relaxation, and in vivo cardiac glucose uptake and diastolic relaxation will be related to ex vivo S6K1 activity and IRS-1 site specific Ser vs. Tyr (P) and the resultant downstream IRS-1/PI3-K/Akt signaling. PUBLIC HEALTH RELEVANCE: Insulin is critical for normal cardiovascular function as well as maintaining normal blood glucose levels. Tissue resistance to the normal metabolic actions of insulin is often present in persons with hypertension and is a precursor for type 2 diabetes mellitus and cardiovascular disease. The fundamental mechanisms underlying insulin resistance in cardiovascular tissue, as well as skeletal muscle, are not well understood and our proposed work is directed at elucidation of this abnormity. A better understanding of factors involved in insulin resistance should help in the development of therapeutic targets to help prevent diabetes and cardiovascular disease.

描述（由申请方提供）：胰岛素（INS）敏感性降低是肥胖、高血压和糖尿病等疾病状态的常见特征。营养过剩（特别是脂肪和碳水化合物摄入过多）是高血压和糖尿病发病率增加的主要因素。这些合并症可能是由于INS介导的血管舒张和心血管（CV）和骨骼肌组织中葡萄糖转运减少所致。除营养过剩外，其他几种机制，如增强的肾素-血管紧张素系统（RAS）激活、炎症和INS代谢信号相关异常，可能有助于解释INS抵抗和高血压之间的联系。有证据表明，营养过剩和血管紧张素II（ANG II）可能通过哺乳动物雷帕霉素靶蛋白（mTOR）/S6激酶1（S6 K1）信号通路促进INS抵抗。mTOR是一种高度保守的营养传感器，通过其S6 K1（一种进化上保守的丝氨酸（Ser）激酶）的磷酸化（P）来调节INS代谢信号传导。越来越多的证据表明，通过过量营养素慢性激活S6 K1，通过增加关键INS信号传导/对接分子INS受体底物蛋白1（IRS-1）的Ser（P），促进脂肪、肝脏和骨骼肌组织中的INS抗性，导致磷酸肌醇3激酶（PI 3-K）参与和蛋白激酶B（Akt）刺激受损。我们最近的工作表明，S6 K1在CV组织中被ANG II激活，导致INS代谢信号转导和生物学后果减少，如一氧化氮（NO）介导的血管舒张受损。该提案旨在研究ANG II和营养过剩单独和共同促进CV和骨骼肌组织中INS抗性的新分子机制。为了评价INS代谢信号传导的CV功能效应，我们将利用我们最先进的啮齿动物成像中心。在INS抵抗状态下，心肌和骨骼肌葡萄糖摄取和代谢受损，导致舒张功能障碍、心肌和骨骼肌血流减弱以及缺血性再适应受损。我们已经表明，INS刺激的葡萄糖摄取受损和舒张功能障碍与肥胖模型中全身和心肌INS代谢信号受损和组织RAS表达增加有关。对于该提案，我们将利用新的敲除和敲低策略以及创新的啮齿动物成像工具来评估增加的S6 K1信号传导（ANG II和/或过量营养素）对心肌功能以及冠状动脉和骨骼微血管血流对INS代谢信号传导的反应的影响。为了解决目标1，我们将在原代培养的内皮细胞，血管平滑肌细胞和心肌细胞中研究ANG II和S6 K1激活和INS信号转导之间的关系。代谢信号结果将与功能测量相关，包括NO产生、心肌细胞葡萄糖转运和舒张。为了进一步探索ANG II和营养过剩对S6 K1的共同作用以及独立作用，Aim 2将关注用ANG II处理的S6 K1-/-和C57 BL/6小鼠的体内/离体效应，所述ANG II产生缓慢的升压反应和/或高脂肪（60%）和高蔗糖（20%）饮食。一组动物将接受0.5 mg/kg/天剂量的AT 1 R阻滞剂（奥美沙坦）给药，该剂量通过遥测确定对db/db小鼠的血压无影响。将通过高胰岛素血症、正葡萄糖钳夹、心脏PET扫描、离体IRS-1（P）和INS代谢信号传导以及心脏和骨骼肌中的葡萄糖摄取来评估INS抵抗。最后，体内INS介导的骨骼肌小动脉和离体冠状小动脉、NO诱导的舒张以及体内心脏葡萄糖摄取和舒张将与离体S6 K1活性和IRS-1位点特异性Ser vs. Tyr（P）以及所得下游IRS-1/PI 3-K/Akt信号传导相关。 公共卫生相关性：胰岛素对正常心血管功能以及维持正常血糖水平至关重要。对胰岛素正常代谢作用的组织抵抗通常存在于高血压患者中，并且是2型糖尿病和心血管疾病的前兆。心血管组织和骨骼肌中胰岛素抵抗的基本机制还不清楚，我们提出的工作旨在阐明这一假设。更好地了解胰岛素抵抗的相关因素有助于开发治疗靶点，以帮助预防糖尿病和心血管疾病。