Role of Lipid Droplets in Hepatitis C Virus Infection

脂滴在丙型肝炎病毒感染中的作用

基本信息

批准号：
8728531
负责人：
Melanie Maria Ott
金额：
$ 47.75万
依托单位：
J. DAVID GLADSTONE INSTITUTES
依托单位国家：
美国
项目类别：
财政年份：
2014
资助国家：
美国
起止时间：
2014-03-01 至 2019-04-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8728531
关键词：
1,2-diacylglycerol Acylation Acyltransferase Address Adipocytes Adipose tissue Affect Antiviral Agents Binding Cell Culture System Cells Chemicals Cholesterol Esters Chronic Chronic Hepatitis C Commit Complex Core Protein Cytoplasm Dengue Virus Development Diglycerides Endoplasmic Reticulum Energy-Generating Resources Enzymes Epidemic Gastroenterology Genotype Hepatitis C Hepatitis C virus Hepatocyte Hepatology Howard Temin Award Human Individual Infectious hepatitides Integration Host Factors Life Cycle Stages Link Lipase Lipids Lipolysis Liver Liver Fibrosis Liver diseases Malignant neoplasm of liver Manuscripts Medicine Membrane Modeling Molecular Morbidity - disease rate Mus National Institute of Allergy and Infectious Disease Nature Nonstructural Protein Nucleocapsid Organelles Paper Patients Phospholipids Play Process Production Property Proteins Publishing RNA replication Recruitment Activity Relative (related person)Risk Risk Factors Role Science Surface Symptoms Testing Therapeutic Intervention Transgenic Mice Triglycerides Viral Viral Proteins Virion Virus Assembly Virus Diseases crosslink diacylglycerol O-acyltransferase editorial global health hepatitis C virus nucleocapsid protein hepatoma cell inhibitor/antagonist innovation insight monolayer mortality mutant new therapeutic target non-alcoholic fatty liver novel novel therapeutics particle protein acyltransferase public health relevance replicase research study small molecule tandem mass spectrometry viral RNA virus pathogenesis web site

项目摘要

DESCRIPTION (provided by applicant): The hepatitis C virus (HCV) epidemic is a global health problem and affects ~170 million people worldwide. In ~80% of cases, viral infection becomes chronic, rendering HCV a leading cause of liver-related morbidity and mortality. A common symptom of chronic HCV infection is steatosis, the abnormal accumulation of lipid droplets in the liver. Steatosis is observed in ~55% of chronically HCV-infected patients and represents an important risk factor for the development of liver fibrosis and cancer. The viral nucleocapsid core expressed in livers of transgenic mice recapitulates this condition; core itself also localizes to the surface of lipid droplets (LDs), a process critical for the assembly of progeny virions at membranes in close proximity to LDs. We recently identified the triglyceride-synthesizing enzyme DGAT1 as a novel host factor for HCV assembly (Herker et al, Nat. Med. 2010). In cells lacking DGAT1 or treated with a DGAT1 inhibitor, core cannot localize to LDs and cannot recruit viral RNA to neighboring endoplasmic reticulum membranes for encapsidation. As a consequence, HCV particle production is severely impaired. We recently published three additional studies that demonstrate 1) that a second HCV protein, NS5A, interacts with DGAT1 and requires DGAT1 for LD localization (Camus et al, J. Biol. Chem. 2013), 2) that core at the surface of LDs decreases the lipolysis of these LDs, thereby causing steatosis (Harris, Herker et al, J. Biol. Chem. 2012), and 3) that LDs play a larger role in HCV infection with a new involvement in HCV RNA replication via a new interaction between the LD- associated protein TIP47 and NS5A (Vogt et al, PLoS Pathog. 2013). We seek to study in molecular detail the role of LDs as critical host organelles in the HCV lifecycle. We propose three experiments. 1) To define the role of DGAT1 in recruiting HCV proteins to LDs. We will test the hypothesis that a tripartite complex of DGAT1, NS5A and core has evolved to co-recruit core and NS5A to DGAT1-generated LDs. We will also determine if NS5A and core are new protein targets for the acyltransferase activity of DGAT1. 2) To determine how the HCV core protein inhibits lipolysis. We will test whether core at the surface of LDs interferes with the recruitment or activity of the triglyceride lipases ATGL/PNPLA2 and PNPLA3, thus inhibiting lipolysis. Because patients infected with different HCV genotypes are at different risks to develop steatosis, we will compare anti-lipolytic activities of core proteins from different viral genotypes. 3) To explore how the NS5A-TIP47 interaction regulates HCV RNA replication. We will determine if LDs serve a dual role in HCV infection: one as membrane and energy sources for HCV RNA replication and another as assembly platforms. We will determine whether binding of NS5A to TIP47 plays an important role in this process. Collectively, our proposed studies will bring new molecular insight into the role of LDs in the HCV lifecycle and may uncover potential novel therapeutic strategies to treat chronic HCV disease.

描述（由申请人提供）：丙型肝炎病毒（HCV）流行是一个全球健康问题，在全球范围内影响约1.7亿人。在约80％的病例中，病毒感染变为慢性，使HCV成为肝有关的发病率和死亡率的主要原因。慢性HCV感染的常见症状是脂肪变性，肝脏中脂质滴的异常积累。在约55％的慢性HCV感染患者中观察到脂肪变性，这代表了肝纤维化和癌症发展的重要危险因素。在转基因小鼠肝脏中表达的病毒核包膜核心概括了这种情况。核心本身还位于脂质液滴（LDS）的表面，这是在与LDS紧邻的膜上组装后代病毒体至关重要的过程。我们最近将甘油三酸酯合成的酶DGAT1确定为HCV组装的新型宿主因子（Herker等，Nat。Med。2010）。在缺乏DGAT1或用DGAT1抑制剂处理的细胞中，Core不能定位于LD，也不能募集病毒RNA到相邻的内质网膜进行封装。结果，HCV颗粒的产生严重受损。 We recently published three additional studies that demonstrate 1) that a second HCV protein, NS5A, interacts with DGAT1 and requires DGAT1 for LD localization (Camus et al, J. Biol. Chem. 2013), 2) that core at the surface of LDs decreases the lipolysis of these LDs, thereby causing steatosis (Harris, Herker et al, J. Biol. Chem. 2012), and 3) that LDs play通过LD-相关蛋白TIP47和NS5A之间的新相互作用，在HCV感染中发挥了更大的作用（Vogt等，PlosPathog。2013）。我们寻求分子详细研究LDS作为HCV生命周期中关键宿主细胞器的作用。我们提出了三个实验。 1）定义DGAT1在将HCV蛋白募集到LDS中的作用。我们将检验以下假设：DGAT1，NS5A和CORE的三方复合物已演变为合作核心核心和NS5A到DGAT1生成的LDS。我们还将确定NS5A和核心是否是DGAT1酰基转移酶活性的新蛋白质靶标。 2）确定HCV核心蛋白如何抑制脂解。我们将测试LDS表面的核心是否会干扰甘油三酸酯脂肪酶ATGL/PNPLA2和PNPLA3的募集或活性，从而抑制脂肪分解。由于感染了不同HCV基因型的患者患脂肪变性的风险不同，因此我们将比较来自不同病毒基因型的核心蛋白的抗脂溶剂。 3）探索NS5A-TIP47相互作用如何调节HCV RNA复制。我们将确定LD在HCV感染中是否起双重作用：一种作为HCV RNA复制的膜和能源，另一个作为组装平台。我们将确定NS5A与TIP47的结合是否在此过程中起重要作用。总的来说，我们提出的研究将使LDS在HCV生命周期中的作用中带来新的分子见解，并可能发现治疗慢性HCV疾病的潜在新型治疗策略。