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: 10251911
• 负责人: Joyce Ying Liu
• 金额: $ 3.35万
• 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/10251911
• 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/antagonist; 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.

项目概要 营养感知（即细胞和生物体感知、报告和响应营养可用性的能力） 是对生命和健康至关重要的基本机制，但在以下情况下常常失调 疾病。虽然某些营养素（例如氨基酸和 ATP）传感机制的发现已经 对它们对疾病的影响、其他必需代谢物可能的机制产生了重要的见解 感测尚未探索。乙酰辅酶A是多种分解代谢、合成代谢和合成代谢交叉点的代谢物 信号通路，因此可能具有独特的地位来报告营养物质的可用性。确实，数据 我们的实验室和其他实验室的数据表明检测到了乙酰辅酶A的可用性。具体来说，我们实验室之前 研究表明，删除或抑制 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 (ACSS2) 以维持乙酰辅酶 A 的核胞质池。 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的了解非常有限。 当通过 ACLY 产生乙酰辅酶A时，该传感途径随后可以参与适应性反应 妥协了。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。 治疗高胆固醇血症。尽管有这种临床治疗方法和抑制剂的潜力 广泛用于患有代谢性疾病的个体，对肝 ACLY 缺陷遗传模型的研究 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（例如非酒精性脂肪肝病）中代偿性 ACSS2 上调 （非酒精性脂肪肝）。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 ACSS2 上调，ii) 抑制脂肪生成乙酰辅酶A的产生和激活这种传感机制具有以下意义： NAFLD 的发病机制是导致线粒体功能和脂肪酸氧化缺陷。我会测试这个 假设，首先（目标 1）通过胆固醇途径代谢物的量化和 SREBP 的评估 转录活性，使用 ACLY 缺陷的体外和体内模型。进一步，我将描述 （目标 2）抑制脂肪生成乙酰辅酶 A 产生的效果（肝脂肪变性体内模型）。 具体来说，我将研究脂肪生成乙酰辅酶A产生的缺陷如何改变脂肪酸氧化和 线粒体功能，并确定这些变化是否依赖于线粒体水平的变化 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够解决一个重要问题 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。