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: 7516096
• 负责人: Robert Charles Noland
• 金额: $ 5.13万
• 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/7516096
• 关键词: Accounting; Acetyl Coenzyme A; Acetylation; Acetylcarnitine; Affect; Biological Assay; Biomedical Research; Cardiovascular Diseases; Carnitine; Carnitine O-Acetyltransferase; Cell Line; Cells; Characteristics; Chronic; Citric Acid Cycle; Collaborations; Condition; Development; Diabetes Mellitus; Diet; Electroporation; Environment; Enzymes; Esters; Fatty Acids; Fatty acid glycerol esters; Figs - dietary; Glucose; Goals; Incidence; Injection of therapeutic agent; Insulin; Insulin Resistance; Laboratories; Link; Lipids; Localized; Mass Spectrum Analysis; Mediating; Metabolic; Mitochondria; Mitochondrial Matrix; Mitochondrial Proteins; Modeling; Molecular; Mus; Muscle; Muscle Cells; Muscle Fibers; Obesity; Oxidative Stress; Pathogenesis; Pathway interactions; Peripheral; Phenotype; Play; Pliability; Predisposition; Protein Acetylation; Protein Overexpression; Public Health; Pyruvate; Pyruvates; Rate; Regulation; Research Institute; Research Personnel; Role; Skeletal Muscle; Stress; Supplementation; Testing; Time; Tissues; acylcarnitine; adenoviral-mediated; base; blood glucose regulation; fatty acid oxidation; feeding; glucose disposal; glucose tolerance; improved; insight; insulin sensitivity; lipid metabolism; mitochondrial dysfunction; mouse model; oxidation; pyruvate dehydrogenase; pyruvate dehydrogenase kinase 4; research study; respiratory; response; restoration

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。出现的一个共同主题是线粒体功能在这些条件下受损。在最近的研究中，我们发现长期高脂肪喂养会导致线粒体呼吸能力下降，同时不完全的β-氧化加速，因此意味着β-氧化和三羧酸循环活性之间的脱节。我们假设线粒体基质酶肉毒碱乙酰转移酶（CrAT）通过其允许从线粒体输出过量不完全β-氧化中间体的作用，在脂质负荷过多期间维持骨骼肌线粒体功能中发挥着关键作用。在骨骼肌细胞培养模型（L6 和 C2C12 细胞系）中使用腺病毒介导的 CrAT 沉默，以及在小鼠中使用肌肉特异性靶向沉默 CrAT（腺病毒注射或电穿孔），我们将探讨 CrAT 在线粒体底物处理中的作用。将采用经典的功能测定和基于质谱的代谢分析来确定 siCrAT 治疗是否会增加对脂质诱导的线粒体功能障碍的易感性，并随后使骨骼肌易于发生胰岛素抵抗。如果观察到表型，我们将探讨 CrAT 是否调节线粒体蛋白乙酰化和/或氧化应激，以评估该酶在调节线粒体功能以响应高脂质环境中的作用背后的潜在机制。这些实验的结果将为了解 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。 公共卫生相关性：肥胖、胰岛素抵抗和糖尿病的发病率正在以惊人的速度增加，并且与脂质代谢和线粒体功能失调密切相关。 CrAT 是一种位于线粒体基质内的酶，可将短链酰基辅酶 A 转化为短链酰基肉碱，然后短链酰基肉碱可从线粒体输出，从而提供在脂质过量条件下维持线粒体功能的机制。拟议的实验将极大地增强我们对 CrAT 在线粒体底物处理调节中的作用的理解，并确定该酶在减轻肥胖、胰岛素抵抗和糖尿病方面的潜在作用。