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.

该项目的总体目标是确定脂肪肝疾病 (FLD) 的代谢和分子基础，这是一种新兴的健康问题，几乎没有治疗选择。2004 年，我们小组对多民族的肝甘油三酯 (TG) 含量进行了首次调查。达拉斯心脏研究 (DHS) 的人群样本显示，与欧洲裔美国人 (EA) 相比，西班牙裔美国人 (AA) 中肝脂肪变性更为常见。为了深入了解这种种族差异的分子基础，我们使用人类遗传学来识别与 FLD 可重复相关的第一个遗传变异 (PNPLA3-148M)，该变异解释了这 3 个种族群体中 HTGC 的大部分血统相关差异。该变异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，具有同等的酒精性肝病进展风险。随后，我们发现了 TM6SF2 中的一个变异，尽管通过完全不同的机制引起脂肪变性，但该变异也与 FLD 的全谱相关。最近，我们发现了第一个可以防止 FLD 进展的变异。这些变异的致病机制，并为治疗干预提供原理验证实验。在目标 1 中，我们将确定 PNPLA3-148M 如何导致肝脂肪变性，并制定逆转这种情况的策略。之前我们展示了 PNPLA3-148M 在脂滴 (LD) 上的积累，在此目的中，我们将使用 148M“敲入”小鼠来模拟与该变体相关的人类病理生理学，从而确定 PNPLA3 在 LD 上的积累如何促进肝脂肪变性。由腺相关病毒 (AAV) 传递的发夹 (sh) RNA 和 siRNA 将用于确定是否敲低PNPLA3-148M 还将靶向控制肝脏中 PNPLA3 表达和 TG 合成的调节机制，我们将确定 TM6SF2 167K 相关肝脂肪变性的分子基础。 VLDL 大量脂化所需的 ER 和高尔基体蛋白，Tm6Sf2-/- 小鼠复制了人类表型。将使用 TM6SF2 敲除肝细胞系来检查 TM6SF2 在 VLDL 组装、运输和分泌中的作用我们将利用蛋白质 C 末端基于赖氨酸的靶向序列来定义亚细胞位点。 TM6SF2 促进新生 VLDL 颗粒的脂化，我们将测试 TM6SF2 作为支架来协调分泌途径中中性脂质添加到 VLDL 的假设。目标 3 我们将重点关注 AA 中常见的 HSD17B13 变异，该变异可在不改变 HTGC 的情况下抵抗 FLD 进展，成功完成这 3 个目标将为肝脏 TG 稳态提供新的见解，并为治疗慢性肝脏提供新的策略和目标。疾病。