Thioesterase-mediated lipotoxicity in liver and thermogenic adipose tissue

肝脏和产热脂肪组织中硫酯酶介导的脂毒性

• 批准号: 10468796
• 负责人: Baran Ersoy
• 金额: $ 42.38万
• 依托单位: WEILL MEDICAL COLL OF CORNELL UNIV
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-13 至 2026-04-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10468796
• 关键词: Ablation; Acetyl Coenzyme A; Acyl Coenzyme A; Adipocytes; Adipose tissue; Anabolism; Biological Availability; Body Weight decreased; Caenorhabditis elegans; Cells; Ceramides; Citric Acid Cycle; Climate; Closure by clamp; Consumption; Data; Deacetylase; Defect; Diet; Dietary Fats; Dietary Sugars; Diglycerides; Disease; Endoplasmic Reticulum; Energy Metabolism; Exhibits; Family member; Fatty Acids; Fractionation; Glucose; Goals; Hepatic; Hepatocyte; Histology; Homeostasis; Human; Hydrolysis; Immunoblot Analysis; Impairment; In Vitro; Indirect Calorimetry; Inner mitochondrial membrane; Insulin Resistance; Intervention; Knockout Mice; Lipids; Liver; Lysine; Measurement; Measures; Mediating; Membrane; Metabolic; Metabolic Diseases; Mission; Mitochondria; Mitochondrial Matrix; Molecular; Mus; National Institute of Diabetes and Digestive and Kidney Diseases; Nutrient; Obesity; Outcome; Overnutrition; Oxidative Stress; Pathogenesis; Pathway interactions; Pharmacology; Phosphorylation; Plasma; Prevention; Production; Protein Acetylation; Protein Kinase C; Proteins; Public Health; Publishing; RNA Interference; Reactive Oxygen Species; Recombinants; Regulation; Research; Research Proposals; Resolution; Role; Sirtuins; Testing; Therapeutic; Thermogenesis; Tissues; base; design; endoplasmic reticulum stress; experimental study; glucose metabolism; glucose production; improved; insulin sensitivity; insulin signaling; knock-down; lipid biosynthesis; lipid metabolism; lipidomics; metabolomics; non-alcoholic fatty liver disease; novel; novel therapeutic intervention; protein activation; response; sugar; trafficking

PROJECT SUMMARY/ABSTRACT Obesity-induced lipotoxicity is the primary pathophysiological defect that predisposes to non-alcoholic fatty liver disease (NAFLD). Because current management options remain limited, identification of new regulatory mechanisms that govern the maladaptive response to overnutrition will serve to identify novel opportunities for pharmacologic intervention. Acyl-CoA thioesterases (Acots) control the cellular utilization of fatty acids by hydrolyzing acyl-CoA into non-esterified fatty acids. Our long-term goal is to define how aberrant Acot activity can be leveraged for therapeutic purposes. The objective of this research is to determine the mechanisms by which Acot9-mediated hydrolysis of acetyl-CoA culminates in metabolic disease. Our preliminary data indicates that Acot9 locates to the inner membrane (IM) of the mitochondria in the liver where it traffics acetyl-CoA towards the citric acid (TCA) cycle. This results in increased hepatic glucose production (HGP) and de novo lipogenesis (DNL) as well as lipotoxicity as evidenced by reactive oxygen species (ROS) and hepatic insulin resistance. In addition to TCA cycle, Acot9 increased acetyl-CoA supply for lysine acetylation of proteins (AcK) by controlling acetyl-CoA bioavailability and by inhibiting the deacetylase sirtuin 3 (Sirt3), which reduces ROS by inhibiting AcK. In contrast to liver, in thermogenic adipose tissue (BAT), cold-induced translocation of Acot9 from IM into mitochondrial matrix suppressed thermogenesis by trafficking acetyl-CoA away from TCA cycle. Our central hypothesis is that obesity-induced activation of Acot9 impairs nutrient homeostasis by promoting lipotoxicity in the liver and by limiting thermogenesis in BAT. The rationale is that the mechanisms of acetyl- CoA trafficking by Acot9 will reveal novel targets for the prevention of lipotoxicity and its pathophysiological consequences. The central hypothesis will be tested in three specific aims: 1) To identify the molecular mechanisms by which hepatic Acot9 promotes hepatic lipotoxicity; 2) To elucidate the mechanisms by which Acot9 in BAT limits thermogenesis; and 3) To determine the mechanisms by which Acot9 controls AcK and ROS in the liver. In Aim 1, the mechanisms of Acot9-induced lipotoxicity, HGP and DNL will be elucidated in mice with liver-specific ablation of Acot9 (Acot9LKO) using lipidomics and metabolomics. Impact on insulin signaling and lipotoxic pathways will be determined in mice and primary hepatocytes. Aim 2 will use mice with BAT-specific ablation of Acot9 for the indirect calorimetry measurements in climate-controlled cages. Clamp, tissue histology and metabolomics will assess the metabolic function of Acot9 in BAT. Cultured brown adipocytes and recombinant Acot9 will be used to determine the mechanism of Acot9 translocation into mitochondrial matrix. Aim 3 will use Acot9LKO/Sirt3–/– double knockout mice to determine the role of Sirt3 in Acot9-mediated regulation of AcK and ROS in the liver. Overall, this proposal will elucidate new mechanisms of thioesterase-mediated control of acetyl-CoA utilization. This is significant because acetyl-CoA is the common breakdown end-product of nearly all dietary lipids and sugars. These studies are expected to establish Acot9 as a tractable target for the management of NAFLD.

项目概要/摘要 肥胖引起的脂毒性是易患非酒精性脂肪肝的主要病理生理缺陷 疾病（NAFLD）。由于当前的管理选择仍然有限，因此需要确定新的监管措施 管理对营养过剩的适应不良反应的机制将有助于确定新的机会 药物干预。酰基辅酶A硫酯酶（Acots）通过以下方式控制细胞对脂肪酸的利用： 将酰基辅酶A水解成非酯化脂肪酸。我们的长期目标是定义异常的 Acot 活动如何 可以用于治疗目的。本研究的目的是通过以下方式确定机制： Acot9 介导的乙酰辅酶 A 水解最终导致代谢疾病。我们的初步数据表明 Acot9 位于肝脏线粒体内膜 (IM)，在那里运输乙酰辅酶 A 进入柠檬酸（TCA）循环。这导致肝葡萄糖产生（HGP）增加并从头开始 脂肪生成 (DNL) 以及活性氧 (ROS) 和肝胰岛素所证明的脂毒性 反抗。除了 TCA 循环之外，Acot9 还增加了蛋白质赖氨酸乙酰化 (AcK) 的乙酰辅酶 A 供应 通过控制乙酰辅酶 A 生物利用度和抑制去乙酰酶 Sirtuin 3 (Sirt3)，从而减少 ROS 通过抑制AcK。与肝脏相反，在产热脂肪组织 (BAT) 中，冷诱导的 Acot9 易位 从 IM 进入线粒体基质通过将乙酰辅酶 A 远离 TCA 循环来抑制生热作用。 我们的中心假设是，肥胖诱导的 Acot9 激活通过促进 肝脏中的脂毒性以及限制 BAT 中的生热作用。其基本原理是乙酰基的机制 Acot9 的 CoA 贩运将揭示预防脂毒性及其病理生理学的新靶点 结果。中心假设将在三个具体目标上进行检验：1）确定分子 肝脏 Acot9 促进肝脏脂毒性的机制； 2）阐明其机制 BAT 中的 Acot9 限制生热作用； 3) 确定 Acot9 控制 AcK 的机制 肝脏中的活性氧。在目标 1 中，Acot9 诱导的脂毒性、HGP 和 DNL 的机制将在 使用脂质组学和代谢组学对 Acot9 (Acot9LKO) 进行肝脏特异性消融的小鼠。对胰岛素的影响 将在小鼠和原代肝细胞中确定信号传导和脂毒性途径。目标 2 将使用小鼠 Acot9 的 BAT 特异性消融用于气候控制笼中的间接量热测量。夹钳， 组织组织学和代谢组学将评估 Acot9 在 BAT 中的代谢功能。培养棕色 脂肪细胞和重组 Acot9 将用于确定 Acot9 易位到脂肪细胞中的机制 线粒体基质。目标 3 将使用 Acot9LKO/Sirt3–/– 双敲除小鼠来确定 Sirt3 在 Acot9 介导的肝脏中 AcK 和 ROS 的调节。总体而言，该提案将阐明新机制 硫酯酶介导的乙酰辅酶A利用控制。这很重要，因为乙酰辅酶 A 是 几乎所有膳食脂质和糖的常见分解最终产物。这些研究预计将 将 Acot9 确立为 NAFLD 管理的易处理目标。