Carnitine Acetyltransferase in Defending Mitochondrial and Metabolic Function

肉碱乙酰转移酶保护线粒体和代谢功能

基本信息

批准号：
8538370
负责人：
DEBORAH M MUOIO
金额：
$ 34.08万
依托单位：
DUKE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2010
资助国家：
美国
起止时间：
2010-07-01 至 2015-03-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8538370
关键词：
Acetyl Coenzyme A Acetylcarnitine Address Adenoviruses Advertising Aging Animals Antidiabetic Drugs Body fat Carbohydrates Carbon Carnitine Carnitine O-Acetyltransferase Chronic Coenzyme A Data Development Diet Elderly Energy Metabolism Enzymes Esters Exercise Tolerance Fatty Acids Fatty acid glycerol esters Genetic Engineering Glucose Glucose Intolerance Goals Heart Homeostasis Human Indirect Calorimetry Insulin Insulin Resistance Knockout Mice Laboratories Levocarnitine Link Lipids Mass Spectrum Analysis Measures Mediating Mediator of activation protein Metabolic Metabolic Control Metabolic Diseases Metabolic stress Metabolic syndrome Metabolism Mitochondria Mitochondrial Matrix Mitochondrial Proteins Modeling Muscle Muscle Fibers Non-Insulin-Dependent Diabetes Mellitus Nutrient Obesity Outcome Outcome Measure Overnutrition Oxidative Stress Physiological Plasma Play Production Property Proteomics Publishing Reaction Recombinants Regulation Respiratory physiology Rodent Role Skeletal Muscle Stress Supplementation Technology Testing Therapeutic Tissues Urine Work acylcarnitine base clinically relevant conditionally essential amino acid diabetes mellitus genetics diabetic glucose tolerance improved insight interest long chain fatty acid loss of function mouse model novel oxidation primary outcome public health relevance pyruvate dehydrogenase research study skeletal small hairpin RNA uptake urinary

项目摘要

DESCRIPTION (provided by applicant): This project seeks to elucidate the role of carnitine acetyltransferase (CrAT) as an important regulator of mitochondrial function and glucose tolerance, and the principal mediator of the antidiabetic actions of L-carnitine therapy. Carnitine acetyltransferase (CrAT) is a mitochondrial matrix enzyme that plays a key role in the synthesis and efflux of short chain carnitine conjugates, such as acetyl-carnitine. This enzyme is most abundant in carnitine-rich tissues such as skeletal muscle and heart, but its precise metabolic function remains largely unexplored. CrAT activity is mainly regulated by availability of L-carnitine, a conditionally essential nutrient that is best known for its obligatory role in permitting mitochondrial uptake and oxidation of long chain fatty acids. In addition to its requisite role in fat oxidation, carnitine also permits the intramitochondrial formation of acylcarnitine conjugates, thereby facilitating mitochondrial efflux of excess carbon fuels. Recent studies by our laboratory suggest that carnitine insufficiency caused by aging and/or overnutrition impairs fuel metabolism and insulin action by compromising CrAT activity. Remarkably, dietary carnitine supplementation improved metabolic outcomes in these models in association with robust increases in plasma and urinary acetyl-carnitine levels. The physiological relevance of acetyl-carnitine production and efflux is poorly understood and surprisingly understudied. We seek to understand the specific role of CrAT as a carnitine effector that defends metabolic homeostasis. We will address two central hypotheses: 1) CrAT plays a key role in regulating mitochondrial substrate switching between glucose and fatty acid fuels, and 2) mitochondrial efflux of CrAT-derived acylcarnitines affords protection against muscle insulin resistance and oxidative stress caused by chronic overnutrition. These hypotheses will be tested using gain- and loss-of-function genetic engineering approaches in primary human skeletal myocytes as well as knockout mouse models. Primary outcome measures will include indirect calorimetry, multiple measures of insulin action and metabolic flux, along with state-of-the-art mass spectrometry-based metabolic profiling.

描述（由申请人提供）：该项目旨在阐明肉碱乙酰转移酶（CRAT）作为线粒体功能和葡萄糖耐受性的重要调节剂，以及L-肉碱治疗的抗糖尿病作用的主要介体。肉碱乙酰转移酶（CRAT）是一种线粒体基质酶，在短链肉碱结合物（如乙酰肉碱）的合成和外排起关键作用。这种酶在富含肉碱的组织（例如骨骼肌和心脏）中最丰富，但其精确的代谢功能在很大程度上尚未探索。 crat活性主要由L-肉碱的可用性调节，L-肉碱是一种有条件必不可少的营养素，其在允许线粒体摄取和长链脂肪酸的氧化方面最有必要的作用而闻名。除了其在脂肪氧化中的必要作用外，肉碱还允许酰基肉碱结合物的室内形成，从而促进过多的碳燃料的线粒体外排。我们的实验室的最新研究表明，由于衰老和/或营养不良而引起的肉碱不足损害燃料代谢和胰岛素作用，通过损害crat活性。值得注意的是，在这些模型中，饮食中补充剂的补充改善了代谢结果，以及血浆和尿乙酰 - 肉碱水平的强大增加。乙酰 - 肉碱的生产和排出的生理相关性知之甚少，并且令人惊讶地研究了。我们试图理解克拉特作为捍卫代谢稳态的肉碱效应子的具体作用。我们将解决两个中心假设：1）在调节葡萄糖和脂肪酸燃料之间的线粒体底物切换中，crat起关键作用，以及2）2）线粒体在cr源性的酰基炭接的线粒体外排，可保护肌肉胰岛素抵抗和氧化应激，导致慢性耐药性。这些假设将使用原代人骨骼肌和基因敲除小鼠模型中的功能和功能遗传工程方法进行测试。主要结局指标将包括间接量热法，胰岛素作用的多种测量和代谢通量，以及基于最新的质谱代谢分析。