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：
9265409
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/9265409
关键词：
Acylation Acyltransferase Address Adipocytes Adipose tissue Affect Antiviral Agents Binding Cell Culture System Cells Chemicals Cholesterol Esters Chronic Chronic Hepatitis C Complex Core Protein Cytoplasm Dengue Infection Development Diglycerides Endoplasmic Reticulum Energy-Generating Resources Enzymes Epidemic Gastroenterology Genotype Hepatitis C Hepatocyte Hepatology Howard Temin Award Human Impairment Individual Infectious hepatitides Integration Host Factors Life Cycle Stages Link Lipase Lipids Lipolysis Liver Liver Fibrosis 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 Risk Risk Factors Role Science Surface Symptoms Testing Therapeutic Intervention Transgenic Mice Triglycerides Viral Viral Proteins Virion Virus Virus Assembly Virus Diseases common symptom crosslink diacylglycerol O-acyltransferase editorial experimental study global health hepatitis C virus nucleocapsid protein hepatoma cell inhibitor/antagonist innovation insight liver development monolayer mortality mutant new therapeutic target non-alcoholic fatty liver novel novel therapeutics particle protein acyltransferase public health relevance replicase small molecule inhibitor 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) 流行是一个全球性健康问题，影响全球约 1.7 亿人。在约 80% 的病例中，病毒感染会变成慢性，使 HCV 成为肝脏相关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，即肝脏中脂滴的异常积累。在约 55% 的慢性 HCV 感染患者中观察到脂肪变性，这是肝纤维化和癌症发生的重要危险因素。在转基因小鼠肝脏中表达的病毒核衣壳核心再现了这种情况；核心本身也定位于脂滴 (LD) 的表面，这是一个对于子代病毒粒子在靠近 LD 的膜上组装的关键过程。我们最近将甘油三酯合成酶 DGAT1 确定为 HCV 组装的新型宿主因子（Herker 等人，Nat. Med. 2010）。在缺乏 DGAT1 或用 DGAT1 抑制剂处理的细胞中，核心不能定位于 LD，也不能将病毒 RNA 招募到邻近的内质网膜上进行衣壳化。结果，HCV颗粒的产生严重受损。我们最近发表了另外三项研究，证明 1) 第二种 HCV 蛋白 NS5A 与 DGAT1 相互作用，并且需要 DGAT1 进行 LD 定位（Camus 等人，J. Biol. Chem. 2013），2) 其核心位于 LD 表面减少这些 LD 的脂肪分解，从而导致脂肪变性（Harris、Herker 等人，J. Biol. Chem. 2012），以及 3) LD 在 HCV 感染中发挥着更大的作用，通过 LD 相关蛋白 TIP47 和 NS5A 之间的新相互作用，新参与 HCV RNA 复制（Vogt 等人，PLoS Pathog. 2013）。我们寻求从分子细节角度研究 LD 作为 HCV 生命周期中关键宿主细胞器的作用。我们提出三个实验。 1) 定义 DGAT1 在招募 HCV 蛋白至 LD 中的作用。我们将测试以下假设：DGAT1、NS5A 和核心的三方复合物已进化为共同招募核心和 NS5A 到 DGAT1 生成的 LD。我们还将确定 NS5A 和 core 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肪分解。我们将测试 LD 表面的核心是否会干扰甘油三酯脂肪酶 ATGL/PNPLA2 和 PNPLA3 的募集或活性，从而抑制脂肪分解。由于感染不同HCV基因型的患者发生脂肪变性的风险不同，因此我们将比较不同病毒基因型的核心蛋白的抗脂肪分解活性。 3) 探讨NS5A-TIP47相互作用如何调节HCV RNA复制。我们将确定 LD 是否在 HCV 感染中发挥双重作用：一是作为 HCV RNA 复制的膜和能源，二是作为组装平台。我们将确定 NS5A 与 TIP47 的结合是否在此过程中发挥重要作用。总的来说，我们提出的研究将为 LD 在 HCV 生命周期中的作用带来新的分子见解，并可能揭示治疗慢性 HCV 疾病的潜在新治疗策略。