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: 10280397
• 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/10280397
• 关键词: Ablation; Acetyl Coenzyme A; Acyl Coenzyme A; Adipocytes; Adipose tissue; Anabolism; Biological; 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.

项目总结/摘要 肥胖引起的脂毒性是导致非酒精性脂肪肝的主要病理生理缺陷 非酒精性脂肪肝（NAFLD）。由于目前的管理选择仍然有限，确定新的监管 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-CoA硫酯酶（Acots）通过以下途径控制脂肪酸的细胞利用： 将酰基辅酶A水解成非酯化脂肪酸。我们的长期目标是确定异常的Acot活动 可以用于治疗目的。本研究的目的是确定机制， Acot 9介导的乙酰辅酶A水解最终导致代谢疾病。我们的初步数据显示 Acot 9位于肝脏线粒体的内膜（IM），在那里它运输乙酰辅酶A 柠檬酸（TCA）循环。这导致肝葡萄糖生成增加（HGP）和新生 脂肪生成（DNL）以及活性氧（ROS）和肝胰岛素证实的脂毒性 阻力除了TCA循环，Acot 9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的生物利用度和通过抑制脱乙酰酶sirtuin 3（Sirt 3）， 通过抑制AcK。与肝脏相反，在产热脂肪组织（BAT）中，冷诱导的Acot 9易位 从IM进入线粒体基质通过运输乙酰辅酶A远离TCA循环来抑制产热。 我们的中心假设是，肥胖诱导的Acot 9激活通过促进营养平衡而损害营养稳态。 肝脏中的脂毒性和限制BAT中的产热。基本原理是乙酰基的机制- Acot 9的CoA运输将揭示预防脂毒性及其病理生理学的新靶点。 后果中心假设将在三个具体目标中进行测试：1）识别分子 肝脏Acot 9促进肝脏脂毒性的机制; 2）阐明Acot 9促进肝脏脂毒性的机制 BAT中的Acot 9限制产热;和3）为了确定Acot 9控制AcK和Aco的机制， 肝脏中的ROS。在目的1中，Acot 9诱导的脂毒性、HGP和DNL的机制将在下文中阐明。 使用脂质组学和代谢组学对Acot 9（Acot 9 LKO）进行肝脏特异性消融的小鼠进行研究。对胰岛素的影响 将在小鼠和原代肝细胞中测定信号传导和脂毒性途径。Aim 2将使用小鼠， 在气候受控笼中进行间接量热法测量的Acot 9的BAT特异性消融。夹钳， 组织组织学和代谢组学将评估BAT中Acot 9的代谢功能。培养棕 将使用脂肪细胞和重组Acot 9来确定Acot 9易位到 线粒体基质目的3将使用Acot 9 LKO/Sirt 3-/-双敲除小鼠来确定Sirt 3在以下中的作用： Acot 9介导的肝脏中AcK和ROS的调节。总的来说，这项建议将阐明新的机制， 硫酯酶介导的乙酰辅酶A利用的控制。这是重要的，因为乙酰辅酶A是 几乎所有膳食脂肪和糖的共同分解最终产物。这些研究预计将 将Acot 9确立为NAFLD管理的易处理靶点。