Genetic and Metabolic Basis of Fatty Liver Disease

脂肪肝的遗传和代谢基础

基本信息

批准号：
10455503
负责人：
JONATHAN Charles COHEN
金额：
$ 60.81万
依托单位：
UT SOUTHWESTERN MEDICAL CENTER
依托单位国家：
美国
项目类别：
财政年份：
2011
资助国家：
美国
起止时间：
2011-08-01 至 2023-07-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10455503
关键词：
African American population Alcoholic Fatty Liver Alcoholic Liver Diseases American C-terminal Cell Fractionation Cell Line Chylomicrons Cirrhosis Cultured Cells Dependovirus Diagnosis Disease Disease Progression Disease Resistance Disease susceptibility Enzymes Ethnic group European Excision Fatty Liver Functional disorder Genes Genetic Genetic Variation Glean Goals Golgi Apparatus Grant Health Heart Hepatic Hepatocyte Hispanic Populations Homeostasis Human Human Genetics Hydrolysis Inflammation Knock-in Mouse Knock-out Kupffer Cells Life Lipids Liver Low Prevalence Low-Density Lipoproteins Lysine Mediating Metabolic Modeling Molecular Mus Natural History Pathogenesis Pathogenicity Pathway interactions Pattern Phenotype Plasma Play Predisposition Prevalence Prevention Primary carcinoma of the liver cells Process Proteins Proteome Resistance Risk Role Sampling Scaffolding Protein Signal Transduction Site Small Interfering RNA Steatohepatitis Surveys Tail Testing Therapeutic Therapeutic Intervention Triglycerides Variant Very low density lipoprotein base cell type chronic liver disease ethnic disparity experimental study fatty liver disease gain of function genetic variant immunocytochemistry insight knock-down lipid transfer protein lipidomics loss of function mouse model multi-ethnic new therapeutic target non-alcoholic non-alcoholic fatty liver disease nonalcoholic steatohepatitis novel therapeutics overexpression particle population based scaffold simple steatosis small hairpin RNA stellate cell trafficking

项目摘要

The overall goal of this project is to define the metabolic and molecular basis of fatty liver disease (FLD), a burgeoning health problem with few therapeutic options. In 2004, our group performed the first survey of hepatic triglyceride (TG) content in a multiethnic population-based sample, the Dallas Heart Study (DHS). This survey showed that hepatic steatosis is much more common in Hispanics and less common in African- Americans (AA) relative to European-Americans (EA). To glean insights into the molecular underpinnings of this ethnic disparity we used human genetics to identify the first genetic variation (PNPLA3-148M) associated reproducibly with FLD. The variant accounts for a majority of the ancestry-related differences in HTGC among these 3 ethnic groups. The variant is not only associated with steatosis, but also steatohepatitis, cirrhosis and hepatocellular carcinoma. It confers equivalent risk for progression of alcoholic liver disease. Subsequently we identified a variant in TM6SF2 that also is associated with the full spectrum of FLD despite causing steatosis by a completely different mechanism. More recently we discovered the first variation that protects against progression of FLD. In this application we build on these discoveries to elucidate the pathogenic mechanisms of these variants and provide proof-of-principle experiments for therapeutic intervention. In Aim 1 we will determine how PNPLA3-148M causes hepatic steatosis and develop strategies to reverse this process. Previously we showed that PNPLA3-148M accumulates on lipid droplets (LD). In this Aim we will determine how accumulation of PNPLA3 on LD promotes hepatic steatosis using a 148M “knockin” mouse to model the human pathophysiology associated with this variant. Short hairpin(sh) RNAs delivered by adeno-associated virus (AAV), and siRNAs will be used to determine if knocking down PNPLA3-148M reverses steatosis. We will also target the regulatory machinery that controls both PNPLA3 expression and TG synthesis in the liver. In Aim 2, we will determine the molecular basis of TM6SF2 167K- associated hepatic steatosis. Previously, we showed that TM6SF2 is an ER and Golgi protein that is required for bulk lipidation of VLDL and that Tm6Sf2-/- mice replicate the human phenotype. We will use a TM6SF2 knockout liver cell line to examine the role of TM6SF2 in VLDL assembly, trafficking, and secretion. We will take advantage of lysine-based targeting sequences at the C-terminal end of the protein to define the subcellular site(s) at which TM6SF2 promotes lipidation of nascent VLDL particles. We will test the hypothesis that TM6SF2 serves as a scaffold to coordinate addition of neutral lipids to VLDL in the secretory pathway. In Aim 3 we will focus on a variant in HSD17B13 that is common in AA and confers resistance to FLD progression without altering HTGC. Successful completion of these 3 aims will provide new insights into hepatic TG homeostasis and new strategies and targets for the treatment of chronic liver disease.

该项目的总体目的是定义脂肪肝病（FLD）的代谢和分子基础，这是一个残破的健康问题，几乎没有治疗选择。 2004年，我们的小组在基于多种族的人群样本《达拉斯心脏研究》（DHS）中对肝甘油三酸酯（TG）含量进行了首次调查。这项调查表明，肝脂肪变性在西班牙裔中更为常见，在非裔美国人（AA）相对于欧洲裔美国人（EA）中较不常见。为了了解对这种种族差异的分子基础的见解，我们使用人类遗传学来识别与FLD相关的第一个遗传变异（PNPLA3-148M）。该变体占这三个族裔中HTGC的大多数与祖先相关的差异。该变体不仅与脂肪变性有关，还与脂肪性肝炎，肝硬化和肝细胞癌有关。赋予酒精性肝病进展的同等风险。随后，我们确定了TM6SF2中的一个变体，该变体也与FLD目的地的完整范围相关，从而通过完全不同的机制引起了脂肪变性。最近，我们发现了预防FLD进展的第一个变化。在此应用中，我们建立在这些发现的基础上，以阐明这些变体的致病机制，并为治疗干预提供原则证明实验。在AIM 1中，我们将确定PNPLA3-148M如何引起肝脂肪变性并制定扭转这一过程的策略。以前，我们表明PNPLA3-148M在脂质液滴（LD）上积聚。在此目标中，我们将确定PNPLA3在LD上的积累如何使用148M“敲蛋白”小鼠促进肝脂肪变性，以模拟与该变体相关的人类病理生理学。由腺相关病毒（AAV）和siRNA传递的短发夹（SH）RNA将用于确定是否击倒PNPLA3-148M是否会逆转脂肪变性。我们还将针对控制肝脏中PNPLA3表达和TG合成的调节机制。在AIM 2中，我们将确定TM6SF2 167K相关的肝脂肪变性的分子基础。以前，我们表明TM6SF2是一种ER和高尔基蛋白，它是VLDL的大量脂肪所必需的，而TM6SF2 - / - 小鼠复制了人类表型。我们将使用TM6SF2敲除肝细胞系来检查TM6SF2在VLDL组装，贩运和分泌中的作用。我们将利用蛋白质C末端的基于赖氨酸的靶向序列来定义TM6SF2促进新生VLDL颗粒脂化的亚细胞位点。我们将检验以下假设：TM6SF2用作支架，以协调在秘密途径中向VLDL添加中性脂质的脚手架。在AIM 3中，我们将重点放在AA中常见的HSD17B13中的变体上，并在不改变HTGC的情况下赋予FLD进展的抵抗力。这三个目标的成功完成将为肝脏TG体内平衡，新的策略和目标提供新的见解，以治疗慢性肝病。