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Park SB, Boyer A, Hu Z, Le D, Liang TJ. Discovery and characterization of a novel HCV inhibitor targeting the late stage of HCV life cycle. Antivir Ther 2020; 24:371-381. [PMID: 30880685 DOI: 10.3851/imp3303] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/03/2019] [Indexed: 10/27/2022]
Abstract
BACKGROUND Currently approved anti-HCV drugs, the direct-acting antivirals (DAAs), are highly effective and target the viral RNA replication stage of the HCV life cycle. Due to high mutation rate of HCV, drug resistant variants can arise during DAA monotherapy. Thus, a combination of DAAs is necessary to achieve a high response rate. Novel HCV inhibitors targeting the HCV late stage such as assembly and release may further improve combination therapy with the DAAs. Here we characterize one late stage-targeting candidate compound, 6-(4-chloro-3-methylphenoxy)-pyridin-3-amine (MLS000833705). METHODS We treated HCV-infected cells with MLS000833705 and other HCV inhibitors and examined HCV RNA and infectious titres. We evaluated the colocalization of HCV core and lipid droplets by confocal microscopy. We performed HCV core-proteinase K digestion assay and several lipid assays to study the mechanism of MLS000833705. RESULTS We showed that MLS000833705 decreased extracellular HCV RNA levels more than intracellular HCV RNA levels in HCV infectious cell culture. Similarly, MLS000833705 reduced infectious HCV titres substantially more in the culture supernatant than intracellularly. Confocal microscopy showed that MLS000833705 did not affect the colocalization of HCV core protein with cellular lipid droplets where HCV assembles. HCV core-proteinase K digestion assay showed that MLS000833705 inhibited the envelopment of HCV capsid. CONCLUSIONS Our study demonstrates that MLS000833705 is a late-stage HCV inhibitor targeting HCV morphogenesis and maturation. Therefore, MLS000833705 can be used as a molecular probe to study HCV maturation and secretion and possibly guide development of a new class of HCV antivirals.
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Affiliation(s)
- Seung Bum Park
- Liver Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Audrey Boyer
- Liver Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Zongyi Hu
- Liver Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Derek Le
- Liver Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - T Jake Liang
- Liver Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
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2
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Ferreira AR, Ramos B, Nunes A, Ribeiro D. Hepatitis C Virus: Evading the Intracellular Innate Immunity. J Clin Med 2020; 9:jcm9030790. [PMID: 32183176 PMCID: PMC7141330 DOI: 10.3390/jcm9030790] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Revised: 03/02/2020] [Accepted: 03/04/2020] [Indexed: 12/25/2022] Open
Abstract
Hepatitis C virus (HCV) infections constitute a major public health problem and are the main cause of chronic hepatitis and liver disease worldwide. The existing drugs, while effective, are expensive and associated with undesirable secondary effects. There is, hence, an urgent need to develop novel therapeutics, as well as an effective vaccine to prevent HCV infection. Understanding the interplay between HCV and the host cells will certainly contribute to better comprehend disease progression and may unravel possible new cellular targets for the development of novel antiviral therapeutics. Here, we review and discuss the interplay between HCV and the host cell innate immunity. We focus on the different cellular pathways that respond to, and counteract, HCV infection and highlight the evasion strategies developed by the virus to escape this intracellular response.
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Affiliation(s)
| | | | | | - Daniela Ribeiro
- Correspondence: ; Tel.: +351-234-247-014; Fax: +351-234-372-587
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3
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González-Aldaco K, Torres-Reyes LA, Ojeda-Granados C, José-Ábrego A, Fierro NA, Román S. Immunometabolic Effect of Cholesterol in Hepatitis C Infection: Implications in Clinical Management and Antiviral Therapy. Ann Hepatol 2018; 17:908-919. [PMID: 30600305 DOI: 10.5604/01.3001.0012.7191] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Hepatitis C virus (HCV) is a lipid-enveloped virion particle that causes infection to the liver, and as part of its life cycle, it disrupts the host lipid metabolic machinery, particularly the cholesterol synthesis pathway. The innate immune response generated by liver resident immune cells is responsible for successful viral eradication. Unfortunately, most patients fail to eliminate HCV and progress to chronic infection. Chronic infection is associated with hepatic fat accumulation and inflammation that triggers fibrosis, cirrhosis, and eventually hepatocellular carcinoma. Despite that the current direct-acting antiviral agents have increased the cure rate of HCV infection, viral genotype and the host genetic background influence both the immune response and lipid metabolism. In this context, recent evidence has shown that cholesterol and its derivatives such as oxysterols might modulate and potentialize the hepatic innate immune response generated against HCV. The impairment of the HCV life cycle modulated by serum cholesterol could be relevant for the clinical management of HCV-infected patients before and after treatment. Alongside, cholesterol levels are modulated either by genetic variations in IL28B, ApoE, and LDLR or by dietary components. Indeed, some nutrients such as unsaturated fatty acids have demonstrated to be effective against HCV replication. Thus, cholesterol modifications may be considered as a new adjuvant strategy for HCV infection therapy by providing a biochemical tool that guides treatment decisions, an improved treatment response and favoring viral clearance. Herein, the mechanisms by which cholesterol contributes to the immune response against HCV infection and how genetic and environmental factors may affect this role are reviewed.
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Affiliation(s)
- Karina González-Aldaco
- Department of Molecular Biology in Medicine, Civil Hospital of Guadalajara, "Fray Antonio Alcalde" and Health Sciences Center, University of Guadalajara, Guadalajara, Jalisco, Mexico
| | - Luis A Torres-Reyes
- Department of Molecular Biology in Medicine, Civil Hospital of Guadalajara, "Fray Antonio Alcalde" and Health Sciences Center, University of Guadalajara, Guadalajara, Jalisco, Mexico
| | - Claudia Ojeda-Granados
- Department of Molecular Biology in Medicine, Civil Hospital of Guadalajara, "Fray Antonio Alcalde" and Health Sciences Center, University of Guadalajara, Guadalajara, Jalisco, Mexico
| | - Alexis José-Ábrego
- Department of Molecular Biology in Medicine, Civil Hospital of Guadalajara, "Fray Antonio Alcalde" and Health Sciences Center, University of Guadalajara, Guadalajara, Jalisco, Mexico
| | - Nora A Fierro
- Department of Molecular Biology in Medicine, Civil Hospital of Guadalajara, "Fray Antonio Alcalde" and Health Sciences Center, University of Guadalajara, Guadalajara, Jalisco, Mexico
| | - Sonia Román
- Department of Molecular Biology in Medicine, Civil Hospital of Guadalajara, "Fray Antonio Alcalde" and Health Sciences Center, University of Guadalajara, Guadalajara, Jalisco, Mexico
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4
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Hu L, Li J, Cai H, Yao W, Xiao J, Li YP, Qiu X, Xia H, Peng T. Avasimibe: A novel hepatitis C virus inhibitor that targets the assembly of infectious viral particles. Antiviral Res 2017; 148:5-14. [PMID: 29074218 DOI: 10.1016/j.antiviral.2017.10.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 08/15/2017] [Accepted: 10/20/2017] [Indexed: 02/06/2023]
Abstract
Direct-acting antivirals (DAAs), which target hepatitis C virus (HCV) proteins, have exhibited impressive efficacy in the management of chronic hepatitis C. However, the concerns regarding high costs, drug resistance mutations and subsequent unexpected side effects still call for the development of host-targeting agents (HTAs) that target host factors involved in the viral life cycle and exhibit pan-genotypic antiviral activity. Given the close relationship between lipid metabolism and the HCV life cycle, we investigated the anti-HCV activity of a series of lipid-lowering drugs that have been approved by government administrations or proven safety in clinical trials. Our results showed that avasimibe, an inhibitor of acyl coenzyme A:cholesterol acyltransferase (ACAT), exhibited marked pan-genotypic inhibitory activity and superior inhibition against HCV when combined with DAAs. Moreover, avasimibe significantly impaired the assembly of infectious HCV virions. Mechanistic studies demonstrated that avasimibe induced downregulation of microsomal triglyceride transfer protein expression, resulting in reduced apolipoprotein E and apolipoprotein B secretion. Therefore, the pan-genotypic antiviral activity and clinically proven safety endow avasimibe exceptional potential as a candidate for combination therapy with DAAs. In addition, the discovery of the antiviral properties of ACAT inhibitors also suggests that inhibiting the synthesis of cholesteryl esters might be an additional target for the therapeutic intervention for chronic HCV infection.
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Affiliation(s)
- Longbo Hu
- Division of Birth Cohort Study, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, 510623, China; State Key Laboratory of Respiratory Disease, Sino-French Hoffmann Institute, School of Basic Medical Science, Guangzhou Medical University, Guangzhou, 511436, China
| | - Jinqian Li
- Institute of Human Virology and Key Laboratory of Tropical Disease Control of Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
| | - Hua Cai
- State Key Laboratory of Respiratory Disease, Sino-French Hoffmann Institute, School of Basic Medical Science, Guangzhou Medical University, Guangzhou, 511436, China
| | - Wenxia Yao
- The Fifth Affiliated Hospital of Guangzhou Medical University, Guangzhou Medical University, Guangzhou, China
| | - Jing Xiao
- State Key Laboratory of Respiratory Disease, Sino-French Hoffmann Institute, School of Basic Medical Science, Guangzhou Medical University, Guangzhou, 511436, China
| | - Yi-Ping Li
- Institute of Human Virology and Key Laboratory of Tropical Disease Control of Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
| | - Xiu Qiu
- Division of Birth Cohort Study, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, 510623, China.
| | - Huimin Xia
- Division of Birth Cohort Study, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, 510623, China; Department of Neonatal Surgery, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, 510623, China.
| | - Tao Peng
- State Key Laboratory of Respiratory Disease, Sino-French Hoffmann Institute, School of Basic Medical Science, Guangzhou Medical University, Guangzhou, 511436, China.
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5
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Pène V, Lemasson M, Harper F, Pierron G, Rosenberg AR. Role of cleavage at the core-E1 junction of hepatitis C virus polyprotein in viral morphogenesis. PLoS One 2017; 12:e0175810. [PMID: 28437468 PMCID: PMC5402940 DOI: 10.1371/journal.pone.0175810] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 03/31/2017] [Indexed: 12/17/2022] Open
Abstract
In hepatitis C virus (HCV) polyprotein sequence, core protein terminates with E1 envelope signal peptide. Cleavage by signal peptidase (SP) separates E1 from the complete form of core protein, anchored in the endoplasmic reticulum (ER) membrane by the signal peptide. Subsequent cleavage of the signal peptide by signal-peptide peptidase (SPP) releases the mature form of core protein, which preferentially relocates to lipid droplets. Both of these cleavages are required for the HCV infectious cycle, supporting the idea that HCV assembly begins at the surface of lipid droplets, yet SPP-catalyzed cleavage is dispensable for initiation of budding in the ER. Here we have addressed at what step(s) of the HCV infectious cycle SP-catalyzed cleavage at the core-E1 junction is required. Taking advantage of the sole system that has allowed visualization of HCV budding events in the ER lumen of mammalian cells, we showed that, unexpectedly, mutations abolishing this cleavage did not prevent but instead tended to promote the initiation of viral budding. Moreover, even though no viral particles were released from Huh-7 cells transfected with a full-length HCV genome bearing these mutations, intracellular viral particles containing core protein protected by a membrane envelope were formed. These were visualized by electron microscopy as capsid-containing particles with a diameter of about 70 nm and 40 nm before and after delipidation, respectively, comparable to intracellular wild-type particle precursors except that they were non-infectious. Thus, our results show that SP-catalyzed cleavage is dispensable for HCV budding per se, but is required for the viral particles to acquire their infectivity and secretion. These data support the idea that HCV assembly occurs in concert with budding at the ER membrane. Furthermore, capsid-containing particles did not accumulate in the absence of SP-catalyzed cleavage, suggesting the quality of newly formed viral particles is controlled before secretion.
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Affiliation(s)
- Véronique Pène
- Université Paris Descartes, EA 4474 “Virologie de l’Hépatite C”, Paris, France
| | - Matthieu Lemasson
- Université Paris Descartes, EA 4474 “Virologie de l’Hépatite C”, Paris, France
| | - Francis Harper
- CNRS UMR 9196, Institut Gustave Roussy, Villejuif, France
| | - Gérard Pierron
- CNRS UMR 9196, Institut Gustave Roussy, Villejuif, France
| | - Arielle R. Rosenberg
- Université Paris Descartes, EA 4474 “Virologie de l’Hépatite C”, Paris, France
- AP-HP, Hôpital Cochin, Service de Virologie, Paris, France
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6
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Kim JH, Sung PS, Lee EB, Hur W, Park DJ, Shin EC, Windisch MP, Yoon SK. GRIM-19 Restricts HCV Replication by Attenuating Intracellular Lipid Accumulation. Front Microbiol 2017; 8:576. [PMID: 28443075 PMCID: PMC5387058 DOI: 10.3389/fmicb.2017.00576] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 03/20/2017] [Indexed: 12/15/2022] Open
Abstract
Gene-associated with retinoid-interferon-induced mortality 19 (GRIM-19) targets multiple signaling pathways involved in cell death and growth. However, the role of GRIM-19 in the pathogenesis of hepatitis virus infections remains unexplored. Here, we investigated the restrictive effects of GRIM-19 on the replication of hepatitis C virus (HCV). We found that GRIM-19 protein levels were reduced in HCV-infected Huh7 cells and Huh7 cells harboring HCV replicons. Moreover, ectopically expressed GRIM-19 caused a reduction in both intracellular viral RNA levels and secreted viruses in HCVcc-infected cell cultures. The restrictive effect on HCV replication was restored by treatment with siRNA against GRIM-19. Interestingly, GRIM-19 overexpression did not alter the level of phosphorylated STAT3 or its subcellular distribution. Strikingly, forced expression of GRIM-19 attenuated an increase in intracellular lipid droplets after oleic acid (OA) treatment or HCVcc infection. GRIM-19 overexpression abrogated fatty acid-induced upregulation of sterol regulatory element-binding transcription factor-1 (SREBP-1c), resulting in attenuated expression of its target genes such as fatty acid synthase (FAS) and acetyl CoA carboxylase (ACC). Treatment with OA or overexpression of SREBP-1c in GRIM-19-expressing, HCVcc-infected cells restored HCV replication. Our results suggest that GRIM-19 interferes with HCV replication by attenuating intracellular lipid accumulation and therefore is an anti-viral host factor that could be a promising target for HCV treatment.
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Affiliation(s)
- Jung-Hee Kim
- The Catholic University Liver Research Center and WHO Collaborating Center of Viral Hepatitis, The Catholic University of KoreaSeoul, South Korea
| | - Pil S Sung
- Laboratory of Immunology and Infectious Diseases, Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and TechnologyDaejeon, South Korea
| | - Eun B Lee
- The Catholic University Liver Research Center and WHO Collaborating Center of Viral Hepatitis, The Catholic University of KoreaSeoul, South Korea
| | - Wonhee Hur
- The Catholic University Liver Research Center and WHO Collaborating Center of Viral Hepatitis, The Catholic University of KoreaSeoul, South Korea
| | - Dong J Park
- The Catholic University Liver Research Center and WHO Collaborating Center of Viral Hepatitis, The Catholic University of KoreaSeoul, South Korea
| | - Eui-Cheol Shin
- Laboratory of Immunology and Infectious Diseases, Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and TechnologyDaejeon, South Korea
| | - Marc P Windisch
- Hepatitis Research Laboratory, Discovery Biology Department, Institut Pasteur Korea, Seongnam-siGyeonggi-do, South Korea
| | - Seung K Yoon
- The Catholic University Liver Research Center and WHO Collaborating Center of Viral Hepatitis, The Catholic University of KoreaSeoul, South Korea
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7
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Grassi G, Di Caprio G, Fimia GM, Ippolito G, Tripodi M, Alonzi T. Hepatitis C virus relies on lipoproteins for its life cycle. World J Gastroenterol 2016; 22:1953-1965. [PMID: 26877603 PMCID: PMC4726671 DOI: 10.3748/wjg.v22.i6.1953] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Revised: 10/19/2015] [Accepted: 12/21/2015] [Indexed: 02/06/2023] Open
Abstract
Hepatitis C virus (HCV) infects over 150 million people worldwide. In most cases, HCV infection becomes chronic causing liver disease ranging from fibrosis to cirrhosis and hepatocellular carcinoma. Viral persistence and pathogenesis are due to the ability of HCV to deregulate specific host processes, mainly lipid metabolism and innate immunity. In particular, HCV exploits the lipoprotein machineries for almost all steps of its life cycle. The aim of this review is to summarize current knowledge concerning the interplay between HCV and lipoprotein metabolism. We discuss the role played by members of lipoproteins in HCV entry, replication and virion production.
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8
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Khachatoorian R, French SW. Chaperones in hepatitis C virus infection. World J Hepatol 2016; 8:9-35. [PMID: 26783419 PMCID: PMC4705456 DOI: 10.4254/wjh.v8.i1.9] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 10/01/2015] [Accepted: 12/18/2015] [Indexed: 02/06/2023] Open
Abstract
The hepatitis C virus (HCV) infects approximately 3% of the world population or more than 185 million people worldwide. Each year, an estimated 350000-500000 deaths occur worldwide due to HCV-associated diseases including cirrhosis and hepatocellular carcinoma. HCV is the most common indication for liver transplantation in patients with cirrhosis worldwide. HCV is an enveloped RNA virus classified in the genus Hepacivirus in the Flaviviridae family. The HCV viral life cycle in a cell can be divided into six phases: (1) binding and internalization; (2) cytoplasmic release and uncoating; (3) viral polyprotein translation and processing; (4) RNA genome replication; (5) encapsidation (packaging) and assembly; and (6) virus morphogenesis (maturation) and secretion. Many host factors are involved in the HCV life cycle. Chaperones are an important group of host cytoprotective molecules that coordinate numerous cellular processes including protein folding, multimeric protein assembly, protein trafficking, and protein degradation. All phases of the viral life cycle require chaperone activity and the interaction of viral proteins with chaperones. This review will present our current knowledge and understanding of the role of chaperones in the HCV life cycle. Analysis of chaperones in HCV infection will provide further insights into viral/host interactions and potential therapeutic targets for both HCV and other viruses.
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9
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Cooperation between the Hepatitis C Virus p7 and NS5B Proteins Enhances Virion Infectivity. J Virol 2015; 89:11523-33. [PMID: 26355084 DOI: 10.1128/jvi.01185-15] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 08/31/2015] [Indexed: 02/07/2023] Open
Abstract
UNLABELLED The molecular mechanisms that govern hepatitis C virus (HCV) assembly, release, and infectivity are still not yet fully understood. In the present study, we sequenced a genotype 2A strain of HCV (JFH-1) that had been cell culture adapted in Huh-7.5 cells to produce nearly 100-fold-higher viral titers than the parental strain. Sequence analysis identified nine mutations in the genome, present within both the structural and nonstructural genes. The infectious clone of this virus containing all nine culture-adapted mutations had 10-fold-higher levels of RNA replication and RNA release into the supernatant but had nearly 1,000-fold-higher viral titers, resulting in an increased specific infectivity compared to wild-type JFH-1. Two mutations, identified in the p7 polypeptide and NS5B RNA-dependent RNA polymerase, were sufficient to increase the specific infectivity of JFH-1. We found that the culture-adapted mutation in p7 promoted an increase in the size of cellular lipid droplets following transfection of viral RNA. In addition, we found that the culture-adaptive mutations in p7 and NS5B acted synergistically to enhance the specific viral infectivity of JFH-1 by decreasing the level of sphingomyelin in the virion. Overall, these results reveal a genetic interaction between p7 and NS5B that contributes to virion specific infectivity. Furthermore, our results demonstrate a novel role for the RNA-dependent RNA polymerase NS5B in HCV assembly. IMPORTANCE Hepatitis C virus assembly and release depend on viral interactions with host lipid metabolic pathways. Here, we demonstrate that the viral p7 and NS5B proteins cooperate to promote virion infectivity by decreasing sphingomyelin content in the virion. Our data uncover a new role for the viral RNA-dependent RNA polymerase NS5B and p7 proteins in contributing to virion morphogenesis. Overall, these findings are significant because they reveal a genetic interaction between p7 and NS5B, as well as an interaction with sphingomyelin that regulates virion infectivity. Our data provide new strategies for targeting host lipid-virus interactions as potential targets for therapies against HCV infection.
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10
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Yamauchi S, Takeuchi K, Chihara K, Sun X, Honjoh C, Yoshiki H, Hotta H, Sada K. Hepatitis C Virus Particle Assembly Involves Phosphorylation of NS5A by the c-Abl Tyrosine Kinase. J Biol Chem 2015. [PMID: 26203192 DOI: 10.1074/jbc.m115.666859] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Hepatitis C virus (HCV) nonstructural protein 5A (NS5A) is thought to regulate the replication of viral RNA and the assembly of virus particles in a serine/threonine phosphorylation-dependent manner. However, the host kinases that phosphorylate NS5A have not been fully identified. Here, we show that HCV particle assembly involves the phosphorylation of NS5A by the c-Abl tyrosine kinase. Pharmacological inhibition or knockdown of c-Abl reduces the production of infectious HCV (J6/JFH1) particles in Huh-7.5 cells without markedly affecting viral RNA translation and replication. NS5A is tyrosine-phosphorylated in HCV-infected cells, and this phosphorylation is also reduced by the knockdown of c-Abl. Mutational analysis reveals that NS5A tyrosine phosphorylation is dependent, at least in part, on Tyr(330) (Tyr(2306) in polyprotein numbering). Mutation of this residue to phenylalanine reduces the production of infectious HCV particles but does not affect the replication of the JFH1 subgenomic replicon. These findings suggest that c-Abl promotes HCV particle assembly by phosphorylating NS5A at Tyr(330).
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Affiliation(s)
- Shota Yamauchi
- From the Division of Genome Science and Microbiology, Department of Pathological Sciences, Faculty of Medical Sciences, the Organization for Life Science Advancement Programs, University of Fukui, Fukui 910-1193, Japan and
| | - Kenji Takeuchi
- From the Division of Genome Science and Microbiology, Department of Pathological Sciences, Faculty of Medical Sciences, the Organization for Life Science Advancement Programs, University of Fukui, Fukui 910-1193, Japan and
| | - Kazuyasu Chihara
- From the Division of Genome Science and Microbiology, Department of Pathological Sciences, Faculty of Medical Sciences, the Organization for Life Science Advancement Programs, University of Fukui, Fukui 910-1193, Japan and
| | - Xuedong Sun
- From the Division of Genome Science and Microbiology, Department of Pathological Sciences, Faculty of Medical Sciences
| | - Chisato Honjoh
- From the Division of Genome Science and Microbiology, Department of Pathological Sciences, Faculty of Medical Sciences, the Third Department of Internal Medicine, Faculty of Medical Sciences, and
| | - Hatsumi Yoshiki
- From the Division of Genome Science and Microbiology, Department of Pathological Sciences, Faculty of Medical Sciences
| | - Hak Hotta
- the Division of Microbiology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan
| | - Kiyonao Sada
- From the Division of Genome Science and Microbiology, Department of Pathological Sciences, Faculty of Medical Sciences, the Organization for Life Science Advancement Programs, University of Fukui, Fukui 910-1193, Japan and
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11
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Apolipoprotein E, but Not Apolipoprotein B, Is Essential for Efficient Cell-to-Cell Transmission of Hepatitis C Virus. J Virol 2015. [PMID: 26202245 DOI: 10.1128/jvi.00577-15] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
UNLABELLED Hepatitis C virus (HCV) infects hepatocytes through two different routes: (i) cell-free particle diffusion followed by engagement with specific cellular receptors and (ii) cell-to-cell direct transmission mediated by mechanisms not well defined yet. HCV exits host cells in association with very-low-density lipoprotein (VLDL) components. VLDL particles contain apolipoproteins B (ApoB) and E (ApoE), which are required for viral assembly and/or infectivity. Based on these precedents, we decided to study whether these VLDL components participate in HCV cell-to-cell transmission in vitro. We observed that cell-to-cell viral spread was compromised after ApoE interference in donor but not in acceptor cells. In contrast, ApoB knockdown in either donor or acceptor cells did not impair cell-to-cell viral transmission. Interestingly, ApoB participated in the assembly of cell-free infective virions, suggesting a differential regulation of cell-to-cell and cell-free HCV infection. This study identifies host-specific factors involved in these distinct routes of infection that may unveil new therapeutic targets and advance our understanding of HCV pathogenesis. IMPORTANCE This work demonstrates that cell-to-cell transmission of HCV depends on ApoE but not ApoB. The data also indicate that ApoB is required for the assembly of cell-free infective particles, strongly suggesting the existence of mechanisms involving VLDL components that differentially regulate cell-free and cell-to-cell HCV transmission. These data clarify some of the questions regarding the role of VLDL in HCV pathogenesis and the transmission of the virus cell to cell as a possible mechanism of immune evasion and open the door to therapeutic intervention.
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12
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Abstract
Chronic hepatitis C virus (HCV) infection results in a progressive disease that may end in cirrhosis and, eventually, in hepatocellular carcinoma. In the last several years, tremendous progress has been made in understanding the HCV life cycle and in the development of small molecule compounds for the treatment of chronic hepatitis C. Nevertheless, the complete understanding of HCV assembly and particle release as well as the detailed characterization and structure of HCV particles is still missing. One of the most important events in the HCV assembly is the nucleocapsid formation which is driven by the core protein, that can oligomerize upon interaction with viral RNA, and is orchestrated by viral and host proteins. Despite a growing number of new factors involved in HCV assembly process, we do not know the three-dimensional structure of the core protein or its topology in the nucleocapsid. Since the core protein contains a hydrophobic C-terminal domain responsible for the binding to cellular membranes, the assembly pathway of HCV virions might proceed via coassembly at endoplasmic reticulum membranes. Recently, new mechanisms involving viral proteins and host factors in HCV particle formation and egress have been described. The present review aims to summarize the advances in our understanding of HCV assembly with an emphasis on the core protein as a structural component of virus particles that possesses the ability to interact with a variety of cellular components and is potentially an attractive target for the development of a novel class of anti-HCV agents.
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Affiliation(s)
- Katarzyna Gawlik
- Department of Immunology and Microbial Science, IMM-9, The Scripps Research Institute, 10550 N. Torrey Pines Rd., La Jolla, CA, 92037, USA
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13
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Boyer A, Dumans A, Beaumont E, Etienne L, Roingeard P, Meunier JC. The association of hepatitis C virus glycoproteins with apolipoproteins E and B early in assembly is conserved in lipoviral particles. J Biol Chem 2014; 289:18904-13. [PMID: 24838241 PMCID: PMC4081931 DOI: 10.1074/jbc.m113.538256] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Revised: 05/15/2014] [Indexed: 12/15/2022] Open
Abstract
In patients chronically infected with hepatitis C virus and in the HCV cell culture system (HCVcc), it is known that highly infectious virus particles have low to very low buoyant densities. These low densities have been attributed to the association of HCV with lipoprotein components, which occur during the viral morphogenesis. The resulting hybrid particles are known as lipoviral particles (LVP); however, very little is known about how these particles are created. In our study, we used Huh7.5 cells to investigate the intracellular association between envelope proteins and apolipoproteins B and E (ApoB and ApoE, respectively). In particular, we were interested in the role of this association in initiating LVP morphogenesis. Co-immunoprecipitation assays revealed that ApoB, ApoE, and HCV glycoproteins formed a protein complex early in the HCV lifecycle. Confocal analyses of naïve, E1E2-transduced and HCVcc-infected cells showed that HCV glycoproteins, ApoB and ApoE were found strongly colocalized only in the endoplasmic reticulum. We also found that HCV glycoproteins, ApoB and ApoE were already associated with intracellular infectious viral particles and, furthermore, that the protein complex was conserved in the infectious viral particles present in the supernatant of infected Huh7.5 cells. The association of HCV glycoproteins with ApoE was also evidenced in the HCVpp system, using the non-hepatic HEK293T cell line. We suggest that the complex formed by HCV E1E2, ApoB, and ApoE may initiate lipoviral particle morphogenesis.
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Affiliation(s)
- Audrey Boyer
- From the INSERM U966, Université François Rabelais and CHRU de Tours, 37032 Tours, France
| | - Amélie Dumans
- From the INSERM U966, Université François Rabelais and CHRU de Tours, 37032 Tours, France
| | - Elodie Beaumont
- From the INSERM U966, Université François Rabelais and CHRU de Tours, 37032 Tours, France
| | - Loïc Etienne
- From the INSERM U966, Université François Rabelais and CHRU de Tours, 37032 Tours, France
| | - Philippe Roingeard
- From the INSERM U966, Université François Rabelais and CHRU de Tours, 37032 Tours, France
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HCV core residues critical for infectivity are also involved in core-NS5A complex formation. PLoS One 2014; 9:e88866. [PMID: 24533158 PMCID: PMC3923060 DOI: 10.1371/journal.pone.0088866] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Accepted: 01/14/2014] [Indexed: 12/12/2022] Open
Abstract
Hepatitis C virus (HCV) infection is a major cause of liver disease. The molecular machinery of HCV assembly and particle release remains obscure. A better understanding of the assembly events might reveal new potential antiviral strategies. It was suggested that the nonstructural protein 5A (NS5A), an attractive recent drug target, participates in the production of infectious particles as a result of its interaction with the HCV core protein. However, prior to the present study, the NS5A-binding site in the viral core remained unknown. We found that the D1 domain of core contains the NS5A-binding site with the strongest interacting capacity in the basic P38-K74 cluster. We also demonstrated that the N-terminal basic residues of core at positions 50, 51, 59 and 62 were required for NS5A binding. Analysis of all substitution combinations of R50A, K51A, R59A, and R62A, in the context of the HCVcc system, showed that single, double, triple, and quadruple mutants were fully competent for viral RNA replication, but deficient in secretion of viral particles. Furthermore, we found that the extracellular and intracellular infectivity of all the mutants was abolished, suggesting a defect in the formation of infectious particles. Importantly, we showed that the interaction between the single and quadruple core mutants and NS5A was impaired in cells expressing full-length HCV genome. Interestingly, mutations of the four basic residues of core did not alter the association of core or NS5A with lipid droplets. This study showed for the first time that basic residues in the D1 domain of core that are critical for the formation of infectious extracellular and intracellular particles also play a role in core-NS5A interactions.
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15
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Hepatocyte nuclear factor 4α and downstream secreted phospholipase A2 GXIIB regulate production of infectious hepatitis C virus. J Virol 2013; 88:612-27. [PMID: 24173221 DOI: 10.1128/jvi.02068-13] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Hepatitis C virus (HCV) is a major cause of chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma in humans. The life cycle of HCV is closely associated with the metabolism of lipids, especially very-low-density lipoprotein (VLDL) in hepatocytes. Hepatocyte nuclear factor 4α (HNF4α), the most abundant transcription factor in the liver, regulates the VLDL secretory pathway. However, the effects of HNF4α on the HCV life cycle are unclear. In this study, we investigated the regulatory effects of HNF4α on HCV assembly and secretion. HCV in HNF4α-deficient hepatocytes showed reduced assembly and secretion but unchanged entry and RNA replication. Bezafibrate, a chemical inhibitor of HNF4α, suppressed HCV assembly and secretion. HNF4α downregulation resulted in rearrangement of cytosolic lipid droplets (LDs), as evidenced by the aggregation of large LDs and distorted cytosolic distribution. Phospholipase A2 GXIIB (PLA2GXIIB), an HNF4α-regulated factor involved in VLDL secretion, was found to be crucial in HCV secretion. PLA2GXIIB expression was upregulated in hepatocytes harboring HCV subgenomic replicons or in HCV-infected hepatocytes. This upregulation was transcriptionally controlled in an HNF4α-dependent manner after HCV infection. Furthermore, PLA2GXIIB combined with microsomal triglyceride transfer protein was found to be responsible for the regulation of HNF4α-induced HCV infectivity. These results suggest that HNF4α and its downstream PLA2GXIIB are important factors affecting the late stage of the HCV life cycle and may serve as potential drug targets for the treatment of HCV infection.
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16
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Miyazaki Y, Fujita M, Nomaguchi M, Adachi A. Structural biology for virus research. Front Microbiol 2012; 3:91. [PMID: 22419916 PMCID: PMC3299956 DOI: 10.3389/fmicb.2012.00091] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2012] [Accepted: 02/23/2012] [Indexed: 11/13/2022] Open
Affiliation(s)
- Yasuyuki Miyazaki
- Department of Microbiology, Institute of Health Biosciences, The University of Tokushima Graduate School Tokushima, Japan
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