Investigating Mechanisms of Acetyl-CoA Sensing and Its Implications in Non-Alcoholic Fatty Liver Disease

研究乙酰辅酶A传感机制及其在非酒精性脂肪肝中的意义

• 批准号: 10392510
• 负责人: Joyce Ying Liu
• 金额: $ 3.42万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-06-01 至 2023-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10392510
• 关键词: ATP Citrate (pro-S)-Lyase; Acetate-CoA Ligase; Acetates; Acetyl Coenzyme A; Address; Affect; Amino Acids; Biological; Carbohydrates; Carbon; Catabolism; Cell physiology; Cells; Cholesterol; Citrates; Clinical; Clinical Treatment; Clinical Trials; Coenzyme A; Data; Defect; Dietary Fats; Disease; Disease Progression; Enzymes; Family; Family member; Fatty Acids; Fatty Liver; Fatty acid glycerol esters; Fructose; Gene Expression; Genes; Genetic; Genetic Models; Genetic Transcription; Goals; Health; Hepatic; High Fat Diet; Homeostasis; Hypoxia; In Vitro; Individual; Knockout Mice; Life; Lipids; Liver; Liver diseases; Mammalian Cell; Mediating; Messenger RNA; Metabolic; Metabolic Diseases; Metabolic stress; Metabolism; Mitochondria; Modeling; Monitor; Nuclear; Nutrient; Organism; Pathogenesis; Pathology; Pathway interactions; Phase III Clinical Trials; Phenotype; Physiology; Play; Positioning Attribute; Prevalence; Process; Production; Protein Isoforms; Proteins; Public Health; Regulation; Reporting; Role; Signal Pathway; Testing; Therapeutic; Tissues; Ubiquinone; Up-Regulation; Work; base; chronic liver disease; detection of nutrient; dietary excess; fatty acid oxidation; genetic manipulation; hypercholesterolemia; improved; in vivo; in vivo Model; inhibitor; insight; lipid biosynthesis; mevalonate; mitochondrial dysfunction; non-alcoholic fatty liver disease; novel; programs; response; tool; transcription factor; transcription factor S-II; treatment strategy

PROJECT SUMMARY Nutrient sensing (i.e. the ability of cells and organisms to sense, report on, and respond to nutrient availability) is a fundamental mechanism that is essential to life and health, but often dysregulated in the context of diseases. While the discovery of sensing mechanisms for some nutrients, such as amino acids and ATP, have yielded critical insight into their implications for disease, the mechanisms other essential metabolites may be sensed remains unexplored. Acetyl-CoA is a metabolite at the intersection of several catabolic, anabolic, and signaling pathways, and therefore, may be uniquely positioned to report on nutrient availability. Indeed, data from our lab and others indicates that acetyl-CoA availability is sensed. Specifically, our lab has previously shown that upon deletion or inhibition of ATP-citrate lyase (ACLY), cells and tissues upregulate Acetyl-CoA synthetase short chain family member 2 (ACSS2) in order to maintain nuclear-cytosolic pools of acetyl-CoA. However, we have a very limited understanding of the mechanisms by which cells sense acetyl-CoA and how this sensing pathway can subsequently engage adaptive responses when acetyl-CoA production via ACLY is compromised. Notably, a liver-specific inhibitor against ACLY is currently in phase 3 clinical trials for the treatment of hypercholesterolemia. Despite this clinical therapeutic and the potential for the inhibitor to be widely used in individuals with metabolic diseases, studies with genetic models of hepatic ACLY deficiency are lacking, and in particular, no studies have investigated the implications of ACLY loss and subsequent compensatory ACSS2 upregulation in metabolic liver disease, such as non-alcoholic fatty liver disease (NAFLD). Based on my preliminary data, I hypothesize i) that the sensitivity of the mevalonate and cholesterol pathway to ACLY loss mediates ACSS2 upregulation via activation of SREBP transcription factors and ii) that suppression of lipogenic acetyl-CoA production and activation of this sensing mechanism has implications in the pathogenesis of NAFLD by causing a defect in mitochondrial function and fatty acid oxidation. I will test this hypothesis, first (aim 1) through quantification of cholesterol pathway metabolites and assessment of SREBP transcriptional activity, using both an in vitro and in vivo model of ACLY deficiency. Further, I will characterize (aim 2) the effect of suppressing lipogenic acetyl-CoA production an in vivo model of hepatic steatosis. Specifically, I will investigate how a deficit in lipogenic acetyl-CoA production alters fatty acid oxidation and mitochondrial function, and determine whether these changes are dependent on alterations in levels of the mevalonate pathway product, ubiquinone. Overall, I expect the results of this study to address an essential mechanism in acetyl-CoA sensing, as well as the functional consequences of targeting acetyl-CoA metabolism in NAFLD, with the potential to impact treatment strategies of existing therapeutics.

项目摘要 营养感测（即细胞和生物体感知、报告和响应营养可用性的能力） 是一种对生命和健康至关重要的基本机制，但在疾病的背景下， 疾病虽然一些营养素（如氨基酸和ATP）的传感机制的发现， 对它们对疾病的影响产生了重要的见解，其他必需代谢物可能是 未被探索的地方。乙酰辅酶A是一种代谢产物，在几个分解代谢，合成代谢， 信号通路，因此，可能是唯一的定位，以报告养分的可用性。事实上，数据 从我们的实验室和其他人表明，乙酰辅酶A的可用性是感知。具体来说，我们的实验室以前 显示在缺失或抑制ATP-柠檬酸裂解酶（ACLY）后，细胞和组织上调乙酰辅酶A 合成酶短链家族成员2（ACSS 2）的蛋白质，以维持乙酰辅酶A的核-胞质液库。 然而，我们对细胞感知乙酰辅酶A的机制以及如何感知乙酰辅酶A的机制的理解非常有限。 当通过ACLY产生乙酰辅酶A时， 暴露了值得注意的是，针对ACLY的肝脏特异性抑制剂目前正在进行3期临床试验， 高胆固醇血症的治疗。尽管这种临床治疗和抑制剂的潜力， 广泛用于代谢性疾病个体，肝ACLY缺乏症遗传模型的研究， 缺乏，特别是没有研究调查ACLY损失和随后的影响， 代谢性肝病（如非酒精性脂肪性肝病）中的代偿性ACSS 2上调 （NAFLD）。根据我的初步数据，我假设i）甲羟戊酸和胆固醇的敏感性 ACLY损失途径通过激活SREBP转录因子介导ACSS 2上调，和ii） 抑制脂肪生成乙酰辅酶A的产生和激活这种传感机制， 通过引起线粒体功能和脂肪酸氧化的缺陷来研究NAFLD的发病机制。我来测试一下 假设，首先（目的1）通过定量胆固醇途径代谢物和评估SREBP 转录活性，使用ACLY缺陷的体外和体内模型。此外，我将描述 (aim 2）在肝脂肪变性的体内模型中抑制脂肪生成乙酰辅酶A产生的作用。 具体来说，我将研究如何在脂肪生成乙酰辅酶A生产赤字改变脂肪酸氧化， 线粒体功能，并确定这些变化是否依赖于水平的改变， 甲羟戊酸途径产物，泛醌。总的来说，我希望这项研究的结果能解决一个重要的问题， 乙酰辅酶A传感机制，以及靶向乙酰辅酶A代谢的功能后果 在NAFLD中，有可能影响现有疗法的治疗策略。