Role of Carnitine Acetyltansferase in Combatting Nutrient Stress

肉碱乙酰转移酶在对抗营养应激中的作用

• 批准号: 8203463
• 负责人: Michael Davies
• 金额: $ 4.84万
• 依托单位: DUKE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-08-01 至 2014-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8203463
• 关键词: Ablation; Acetyl Coenzyme A; Acetylation; Acetylcarnitine; Acyl Coenzyme A; Adipose tissue; Adult; Amino Acids; Antidiabetic Drugs; Biochemistry; Carbon; Carnitine; Carnitine O-Acetyltransferase; Cellular Membrane; Citric Acid Cycle; Coenzyme A; Commit; Cultured Cells; Data; Electron Transport; Energy Metabolism; Enzymes; Equilibrium; Excretory function; Fasting; Fatty Acids; Functional disorder; Genetic; Glucose; Goals; Heart; Hepatocyte; Homeostasis; Investigation; Laboratories; Levocarnitine; Light; Liver; Lysine; Mass Spectrum Analysis; Mediating; Metabolic; Metabolic Diseases; Metabolic Pathway; Metabolism; Mitochondria; Mitochondrial Matrix; Mus; Muscle; Muscle Cells; National Research Service Awards; Natural regeneration; Non-Insulin-Dependent Diabetes Mellitus; Nuclear; Nutrient; Obesity; Pathway interactions; Pattern; Physiological; Plasma; Play; Positioning Attribute; Production; Property; Protein Acetylation; Pyruvate Dehydrogenase Complex; Reaction; Risk; Rodent; Role; Site; Skeletal Muscle; Source; Stress; Structure; Supplementation; System; Techniques; Testing; Therapeutic; Tissues; acyl group; acylcarnitine; age related; base; clinically relevant; combat; diabetic; energy balance; feeding; glucose tolerance; improved; insight; interest; knockout gene; mouse model; overexpression; oxidation; pyruvate dehydrogenase; stem; trafficking; urinary

DESCRIPTION (provided by applicant): Carnitine acetyltransferase (CrAT) is a freely reversible mitochondrial matrix enzyme that catalyzes the exchange of short-chain acyl groups between CoA and carnitine. Unlike their acyl-CoA counterparts, acylcarnitines can traverse cellular membranes. Accordingly, the interconversion between these molecules can potentially impact cellular, and perhaps inter-tissue carbon trafficking. The primary substrate of CrAT, acetyl-CoA, holds a prominent position in intermediary metabolism as the two-carbon universal end product of fatty acid, glucose and amino acid oxidation. As its major metabolic fate, acetyl-CoA typically enters the tricarboxylic acid (TCA) cycle where it drives production of reducing equivalents that in turn fuel the electron transport chain. CrAT purportedly acts to export excess carbon fuels from the mitochondria during conditions wherein the production of short-chain acyl-CoAs exceeds TCA cycle flux. By doing so, this reaction is thought to play a key role in regenerating free CoA, modulating mitochondrial acetyl-CoA/CoA balance and relieving acetyl-CoA-mediated inhibition of pyruvate dehydrogenase (PDH), the committed step in glucose oxidation. Mounting evidence from our laboratory suggest that CrAT plays a critical role in regulating whole body substrate selection and glucose tolerance; and that CrAT inactivity might contribute to obesity- and age-related metabolic dysfunction. This NRSA application proposes to elucidate the role of this enzyme in regulating whole body and mitochondrial energy homeostasis utilizing immunoaffinity purification techniques and physiological characterizations of genetic mouse models. First, we will test the hypothesis that one of the mechanisms through which CrAT controls energy metabolism is by regulating nuclear and/or non-nuclear protein acetylation. This is an important and timely line of investigation in light of the growing number of metabolic pathways that appear to be modulated by reversible acetylation. Second, we will use an inducible gene knockout approach to determine whether total body loss of CrAT negates the antidiabetic actions of carnitine therapy. These studies are expected to shed clinically relevant insights on the role of this enzyme in combating nutrient stress and metabolic disease. PUBLIC HEALTH RELEVANCE: The overarching goal of this project is to elucidate mechanisms through which supplemental L- carnitine improves glucose tolerance in obese and diabetic rodents. Results from the proposed studies are likely to yield new insights regarding the therapeutic properties of L-carnitine, a conditionally essential nutrient, while also advancing our understanding of why obesity increases risk of metabolic disorders such as type 2 diabetes. These are clinically relevant topics of intense scientific interest and controversy.

描述（由申请人提供）：肉碱乙酰转移酶（CRAT）是一种可自由逆转的线粒体基质酶，可催化COA和肉碱之间的短链酰基基团的交换。与它们的酰基辅酶A型酰基辅助剂不同，酰基肉碱可以遍历细胞膜。因此，这些分子之间的相互转换可能会影响细胞，甚至可能影响组织间的碳贩运。克拉特的主要底物，乙酰-COA，在中间代谢中是脂肪酸，葡萄糖和氨基酸氧化的两碳通用最终产物的重要位置。作为其主要代谢命运，乙酰辅酶A通常进入三羧酸（TCA）周期，在那里它驱动了还原等效物的生产，从而为电子传输链燃料燃料。据称，在短链酰基-COA的产生超过TCA循环通量的情况下，据称是从线粒体中输出过量的碳燃料。通过这样做，人们认为这种反应在再生自由COA，调节线粒体乙酰-COA/COA平衡中起着关键作用，并缓解乙酰-COA介导的丙酮酸脱氢酶（PDH）的抑制作用，这是葡萄糖氧化中所做的步骤。我们实验室的越来越多的证据表明，克拉特在调节全身底物选择和葡萄糖耐受方面起着至关重要的作用。而且这种不活跃可能导致肥胖和年龄相关的代谢功能障碍。这种NRSA应用建议阐明该酶在调节全身和使用免疫亲和力纯化技术和遗传小鼠模型生理特征的线粒体能量稳态中的作用。首先，我们将检验以下假设：crat控制能量代谢的一种机制是调节核和/或非核蛋白乙酰化。鉴于似乎通过可逆乙酰化调节的代谢途径的数量越来越大，这是一项重要且及时的研究。其次，我们将使用诱导型基因敲除方法来确定crat的总体损失是否否定了肉碱疗法的抗糖尿病作用。预计这些研究将对这种酶在对抗营养应激和代谢疾病中的作用上具有临床上相关的见解。 公共卫生相关性：该项目的总体目标是阐明机制，通过这种机制，补充L-肉碱可提高肥胖和糖尿病啮齿动物的葡萄糖耐受性。拟议的研究的结果可能会产生有关L-肉碱治疗特性的新见解，L-肉碱是一种必不可少的养分，同时也促进了我们对肥胖为何增加代谢性疾病（例如2型糖尿病）的风险的理解。这些是激烈的科学兴趣和争议的临床相关主题。