Role of carnitine acetyltransferase in mitochondrial function and insulin action

肉碱乙酰转移酶在线粒体功能和胰岛素作用中的作用

• 批准号: 7407697
• 负责人: Robert Charles Noland
• 金额: $ 4.96万
• 依托单位: DUKE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-14 至 2009-09-13
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7407697
• 关键词: Biological Assay; Carnitine O-Acetyltransferase; Cell Line; Chronic; Citric Acid Cycle; Condition; Development; Diabetes Mellitus; Electroporation; Environment; Enzymes; Fatty acid glycerol esters; Goals; Incidence; Injection of therapeutic agent; Insulin; Insulin Resistance; Link; Lipids; Localized; Mass Spectrum Analysis; Metabolic; Mitochondria; Mitochondrial Matrix; Mitochondrial Proteins; Modeling; Mus; Muscle; Muscle Fibers; Obesity; Oxidative Stress; Phenotype; Play; Predisposition; Protein Acetylation; Public Health; Rate; Regulation; Role; Skeletal Muscle; Time; acylcarnitine; adenoviral-mediated; base; feeding; insight; lipid metabolism; mitochondrial dysfunction; oxidation; research study; respiratory; response

DESCRIPTION (provided by applicant): The long-term goal of this project is to explore mechanisms linked to lipid-induced insulin resistance. A common theme emerging is that mitochondrial function is impaired in these conditions. In recent studies we discovered chronic high fat feeding resulted in diminished mitochondrial respiratory capacity at a time when incomplete ¿-oxidation was accelerated, thus implying a disconnect between ¿-oxidation and tricarboxylic acid cycle activity. We hypothesize that the mitochondrial matrix enzyme carnitine acetyltransferase (CrAT), through its action allowing the export of excess incomplete ¿-oxidative intermediates from the mitochondria, plays a critical role in maintaining skeletal muscle mitochondrial function under periods of excess lipid burden. Using adenoviral-mediated silencing of CrAT in skeletal muscle cell culture models (L6 and C2C12 cell lines), as well as muscle specific targeted silencing of CrAT (adenoviral injection or electroporation) in mice, we will explore the role of CrAT in mitochondrial substrate handling. Classic functional assays and mass spectrometry-based metabolic profiling will be employed to determine whether siCrAT treatment increases susceptibility to lipid-induced mitochondrial dysfunction and subsequently predisposes skeletal muscle toward the development of insulin resistance. Provided a phenotype is observed we will explore whether CrAT modulates mitochondrial protein acetylation &/or oxidative stress to assess potential mechanisms behind the role of this enzyme in regulating mitochondrial function in response to a high lipid environment. Results from these experiments will provide valuable insights into the role of CrAT in lipid-induced mitochondrial dysfunction and insulin resistance. PUBLIC HEALTH RELEVANCE: The incidence of obesity, insulin resistance, and diabetes are increasing at alarming rates and are closely associated with dysregulation of lipid metabolism and mitochondrial function. CrAT, an enzyme localized within the mitochondrial matrix, converts short chain acyl-CoAs to short chain acylcarnitines which can then be exported from the mitochondria, thereby providing a mechanism to maintain mitochondrial function under conditions of lipid excess. The proposed experiments will greatly enhance our understanding of the role of CrAT in the regulation of mitochondrial substrate handling, as well as establishing a potential role of this enzyme in the alleviation of obesity, insulin resistance, and diabetes.

描述（由申请人提供）：该项目的长期目标是探索与脂质诱导的胰岛素抵抗相关的机制。一个共同的主题是线粒体功能在这些情况下受损。在最近的研究中，我们发现慢性高脂肪喂养导致线粒体呼吸能力下降，同时不完全氧化加速，这意味着氧化和三羧酸循环活性之间存在脱节。我们假设线粒体基质酶肉碱乙酰转移酶（CrAT），通过其允许从线粒体输出过量的不完全氧化中间体的作用，在过量脂质负担时期维持骨骼肌线粒体功能中起关键作用。通过在骨骼肌细胞培养模型（L6和C2C12细胞系）中腺病毒介导的CrAT沉默，以及小鼠肌肉特异性靶向CrAT沉默（腺病毒注射或电穿孔），我们将探索CrAT在线粒体底物处理中的作用。将采用经典功能分析和基于质谱的代谢谱分析来确定siCrAT治疗是否会增加脂质诱导的线粒体功能障碍的易感性，并随后使骨骼肌倾向于胰岛素抵抗的发展。如果观察到表型，我们将探索CrAT是否调节线粒体蛋白乙酰化和/或氧化应激，以评估该酶在高脂环境下调节线粒体功能的潜在机制。这些实验的结果将为CrAT在脂质诱导的线粒体功能障碍和胰岛素抵抗中的作用提供有价值的见解。