Role of Hepatic GDPD3 in Mechanisms of Lipid Metabolism

肝脏 GDPD3 在脂质代谢机制中的作用

基本信息

批准号：
9765301
负责人：
Chia-Chi Chuang Key
金额：
$ 11.64万
依托单位：
WAKE FOREST UNIVERSITY HEALTH SCIENCES
依托单位国家：
美国
项目类别：
财政年份：
2018
资助国家：
美国
起止时间：
2018-09-01 至 2022-08-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9765301
关键词：
Address Adenoviruses Adult Affect Albumins Anabolism Antibodies Automobile Driving Calnexin Cell Line Cell membrane Complex Confocal Microscopy Data Developed Countries Developing Countries Diabetes Mellitus Diet Disease Endoplasmic Reticulum Environmental Risk Factor Enzymes Etiology Fatty Acids Fatty Liver Fatty acid glycerol esters Gene Expression Genes Genetic Glycerol Glycerophospholipids Goals Golgi Apparatus Green Fluorescent Proteins HepG2 Hepatic Hepatitis C Hepatocyte High Prevalence Homeostasis Human Hyperlipidemia Incubated Knowledge Link Lipids Liver Location Lysophosphatidic Acid Receptors Lysophosphatidylcholines Lysophospholipase Lysophospholipids Mass Spectrum Analysis Membrane Membrane Proteins Mentors Molecular Mus Na(+)-K(+)-Exchanging ATPase Natural History Oleic Acids PPAR alpha PPAR gamma Pathogenesis Pathway interactions Pharmaceutical Preparations Physiological Population Prevalence Primary carcinoma of the liver cells Production Property Proteins Radioisotopes Rattus Regulation Reporting Research Personnel Role Small Interfering RNA Substrate Specificity Time Training Triglyceride Metabolism Triglycerides United States United States Food and Drug Administration adult obesity career causal variant enzyme pathway experience fatty acid oxidation gain of function glucose metabolism glycerophosphodiester phosphodiesterase hepatoma cell improved inorganic phosphate interdisciplinary approach knock-down lipid biosynthesis lipid metabolism liver transplantation loss of function lysophosphatidic acid macrogolgin male metabolic phenotype multidisciplinary non-alcoholic fatty liver disease novel overexpression promoter receptor small hairpin RNA standard care targeted treatment therapeutic target uptake vector control very low density lipoprotein triglyceride

项目摘要

PROJECT SUMMARY/ABSTRACT Nonalcoholic fatty liver disease (NAFLD), affecting ~30% of the U.S. population, is projected to replace hepatitis C as the leading cause of liver transplantation by 2020. Developing effective NAFLD treatments is hampered by a poor understanding of its underlying mechanisms, including complex interactions between genetic and environmental factors. Glycerophosphodiester phosphodiesterase domain-containing protein 3 (GDPD3) is a newly discovered enzyme containing lysophospholipase D activity that converts lysophospholipid to lysophosphatidic acid (lysoPA) in non-hepatic cells. Mammalian GDPD3 has not previously been implicated in hepatic lipid metabolism. Our preliminary data indicates a positive correlation between human GDPD3 expression and triglyceride (TG) accumulation in hepatocytes and mouse livers, suggesting a novel gene in the regulation of hepatic TG homeostasis. Nonetheless, the intracellular locations, substrate specificity, physiological function, and molecular mechanisms of human GDPD3 in hepatocytes/livers are unknown. Therefore, in this study, with the guidance of a highly experienced multi-disciplinary mentoring group, we propose to investigate enzymatic properties of human GDPD3 and explore whether human GDPD3 is a causal gene for hepatic steatosis. More specifically, we are asking three questions: 1) Is human GDPD3 an endoplasmic reticulum membrane-associated enzyme containing lysophospholipase D activity? 2) Does human GDPD3 increase lysoPA production resulting in increased hepatic TG synthesis and accumulation via the glycerol phosphate pathway? 3) Does human GDPD3-produced lysoPA activate peroxisome proliferator- activated receptor gamma (PPARγ) which enhances hepatic steatosis via increased fatty acid (FA) uptake and TG synthesis? To answer these questions, we will overexpress human GDPD3 in hepatoma cell lines and in mouse liver to determine: a) the effect of human GDPD3 overexpression on oleic acid-induced TG accumulation in hepatoma cells and diet-induced hepatic steatosis in mice; b) the subcellular localization of human GDPD3 in hepatoma cells and mouse primary hepatocytes; and c) the amount and molecular species of GDPD3 lipid substrates and products in mouse livers. Liver-specific human GDPD3 overexpressing mice with loss-of-function or gain-of-function in PPARγ will be fed chow or a Western-type diet to induce hepatic steatosis. We will perform comprehensive hepatic and systemic metabolic phenotyping on these mice. Primary hepatocytes will be used to investigate de novo lipogenesis, FA uptake and incorporation into TG, FA oxidation, and very low density lipoprotein-TG secretion using radioactive isotopes. When the proposed aims are achieved, we will have a better mechanistic understanding of the relationship between human GDPD3 and hepatic steatosis, to address the gap in knowledge regarding NAFLD pathogenesis and inform strategies for its treatment. Finally, this proposal provides the necessary training and mentored guidance for the applicant to transition to a successful career as an independent investigator in lipid and glucose metabolism.

项目摘要/摘要影响约30％美国人群的非酒精性脂肪肝病（NAFLD）预计将取代到2020年，丙型肝炎是肝移植的主要原因。开发有效的NAFLD治疗是由于对其潜在机制的不良理解所阻碍，包括遗传和环境因素。含甘油磷酸二酯酶结构蛋白3 （GDPD3）是一种含有溶血磷脂酶D活性的新发现的酶，可转化溶血磷脂在非羊皮细胞中溶物磷脂酸（Lysopa）。哺乳动物GDPD3以前尚未暗示在肝脂质代谢中。我们的初步数据表明人GDPD3之间存在正相关在肝细胞和小鼠肝脏中的表达和甘油三酸酯（TG）积累，表明在肝TG稳态的调节。但是，细胞内位置，底物特异性，肝细胞/肝脏中人GDPD3的生理功能和分子机制尚不清楚。因此，在这项研究中，在经验丰富的多学科指导小组的指导下，我们提出研究人GDPD3的酶特性并探讨人GDPD3是否是因果用于肝脂肪变性的基因。更具体地说，我们问三个问题：1）内质网膜相关酶含有溶血磷脂酶D活性？ 2）做人类GDPD3增加了lysopa的产生磷酸甘油途径？ 3）人类GDPD3生产的lysopa是否激活过氧化物组增殖物 - 活化的受体伽马（PPARγ）通过增加脂肪酸（FA）摄取和 TG合成？要回答这些问题，我们将在肝瘤细胞系和小鼠肝脏确定：a）人GDPD3过表达对油酸诱导的TG的影响肝癌细胞中的积累和饮食诱导的小鼠肝脂肪变性； b）肝癌细胞和小鼠原发性肝细胞中的人GDPD3； c）数量和分子物种鼠标寿命中的GDPD3脂质底物和产品。肝特异性人GDPD3过表达小鼠在PPARγ中的功能丧失或功能障碍时，将被喂食或西方型饮食以诱导肝脂肪变性。我们将对这些小鼠进行全面的肝和全身代谢表型。基本的肝细胞将用于调查从头脂肪生成，FA摄取和保险使用放射性同位素氧化和非常低的密度脂蛋白-TG分泌。当提议的目标实现了，我们将对人GDPD3和肝脏脂肪变性，以解决有关NAFLD发病机理的知识的差距，并为其策略提供依据治疗。最后，该提案为申请人提供了必要的培训和修改指导过渡到成功的职业生涯，成为脂质和葡萄糖代谢的独立研究者。