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Xing Y, Chen R, Li F, Xu B, Han L, Liu C, Tong Y, Jiu Y, Zhong J, Zhou GC. Discovery of a fused bicyclic derivative of 4-hydroxypyrrolidine and imidazolidinone as a new anti-HCV agent. Virology 2023; 586:91-104. [PMID: 37506590 DOI: 10.1016/j.virol.2023.07.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 07/12/2023] [Accepted: 07/13/2023] [Indexed: 07/30/2023]
Abstract
Hepatitis C virus (HCV) infection causes severe liver diseases and remains a major global public health concern. Current direct-acting antiviral (DAA)-based therapies that target viral proteins involving HCV genome replication are effective, however a minority of patients still fail to cure HCV, rendering a window to develop additional antivirals particularly targeting host functions involving in HCV infection. Here, we utilized the HCV infection cell culture system (HCVcc) to screen in-house compounds bearing host-interacting preferred scaffold for the antiviral activity. Compound HXL-10, a novel fused bicyclic derivative of pyrrolidine and imidazolidinone, was identified as a potent anti-HCV agent with a low cytotoxicity and high specificity. Mechanistic studies showed that HXL-10 neither displayed a virucidal effect nor inhibited HCV genomic RNA replication. Instead, HXL-10 might inhibit HCV assembly by targeting host functions. In summary, we developed a novel anti-HCV agent that may potentially offer additive benefits to the current anti-HCV DDA.
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Affiliation(s)
- Yifan Xing
- Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China; University of Chinese Academy of Sciences, Beijing, China
| | - Ran Chen
- School of Pharmaceutical Sciences, Nanjing Tech University, Nanjing, Jiangsu, China
| | - Feng Li
- School of Pharmaceutical Sciences, Nanjing Tech University, Nanjing, Jiangsu, China
| | - Bin Xu
- School of Pharmaceutical Sciences, Nanjing Tech University, Nanjing, Jiangsu, China
| | - Lin Han
- Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China; University of Chinese Academy of Sciences, Beijing, China; ShanghaiTech University, Shanghai, China
| | - Chaolun Liu
- Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China; ShanghaiTech University, Shanghai, China
| | - Yimin Tong
- Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China
| | - Yaming Jiu
- Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China; University of Chinese Academy of Sciences, Beijing, China.
| | - Jin Zhong
- Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China; University of Chinese Academy of Sciences, Beijing, China; ShanghaiTech University, Shanghai, China.
| | - Guo-Chun Zhou
- School of Pharmaceutical Sciences, Nanjing Tech University, Nanjing, Jiangsu, China.
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2
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Characterization of a multipurpose NS3 surface patch coordinating HCV replicase assembly and virion morphogenesis. PLoS Pathog 2022; 18:e1010895. [PMID: 36215335 PMCID: PMC9616216 DOI: 10.1371/journal.ppat.1010895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 10/28/2022] [Accepted: 09/25/2022] [Indexed: 11/16/2022] Open
Abstract
The hepatitis C virus (HCV) life cycle is highly regulated and characterized by a step-wise succession of interactions between viral and host cell proteins resulting in the assembly of macromolecular complexes, which catalyse genome replication and/or virus production. Non-structural (NS) protein 3, comprising a protease and a helicase domain, is involved in orchestrating these processes by undergoing protein interactions in a temporal fashion. Recently, we identified a multifunctional NS3 protease surface patch promoting pivotal protein-protein interactions required for early steps of the HCV life cycle, including NS3-mediated NS2 protease activation and interactions required for replicase assembly. In this work, we extend this knowledge by identifying further NS3 surface determinants important for NS5A hyperphosphorylation, replicase assembly or virion morphogenesis, which map to protease and helicase domain and form a contiguous NS3 surface area. Functional interrogation led to the identification of phylogenetically conserved amino acid positions exerting a critical function in virion production without affecting RNA replication. These findings illustrate that NS3 uses a multipurpose protein surface to orchestrate the step-wise assembly of functionally distinct multiprotein complexes. Taken together, our data provide a basis to dissect the temporal formation of viral multiprotein complexes required for the individual steps of the HCV life cycle.
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3
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Sokolova TM. [Hepatitis C virus (Flaviviridae: Hepacivirus: Hepacivirus C): regulation of signaling reactions of innate immunity]. Vopr Virusol 2021; 65:307-316. [PMID: 33533227 DOI: 10.36233/0507-4088-2020-65-6-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Accepted: 01/07/2021] [Indexed: 12/21/2022]
Abstract
Studying the regulation of signaling reactions of innate immunity by the hepatitis C virus (HCV) will help to reveal the causes of the transition of the acute form of the disease to a chronic course. The molecular mechanisms of activation by HCV RNA of innate immunity receptors TLR and RLR and signal transduction processes leading to the synthesis of IFN and inflammatory cytokines are considered. The inhibitory effects of non-structural and structural HCV proteins on immune signaling reactions are analyzed in detail. The information presented is the result of an analysis of literature data published in international databases mainly over the past 5 years. In conclusion, signaling receptors are proposed as targets for the development of new antiviral drugs with immunotherapeutic activity.
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Affiliation(s)
- T M Sokolova
- D.I. Ivanovsky Institute of Virology of National Research Centre for Epidemiology and Microbiology named after the honorary academician N.F. Gamaleya
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4
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Zheng F, Li N, Xu Y, Zhou Y, Li YP. Adaptive mutations promote hepatitis C virus assembly by accelerating core translocation to the endoplasmic reticulum. J Biol Chem 2021; 296:100018. [PMID: 33144326 PMCID: PMC7949066 DOI: 10.1074/jbc.ra120.016010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 10/22/2020] [Accepted: 11/03/2020] [Indexed: 12/14/2022] Open
Abstract
The envelopment of hepatitis C virus (HCV) is believed to occur primarily in the endoplasmic reticulum (ER)-associated membrane, and the translocation of viral Core protein from lipid droplets (LDs) to the ER is essential for the envelopment of viral particles. However, the factors involved are not completely understood. Herein, we identified eight adaptive mutations that enhanced virus spread and infectivity of genotype 1a clone TNcc in hepatoma Huh7 cells through long-term culture adaptation and reverse genetic study. Of eight mutations, I853V in NS2 and C2865F in NS5B were found to be minimal mutation sets that enabled an increase in virus production without apparently affecting RNA replication, thus suggesting its roles in the post-replication stage of the HCV life cycle. Using a protease K protection and confocal microscopy analysis, we demonstrated that C2865F and the combination of I853V/C2865F enhanced virus envelopment by facilitating Core translocation from the LDs to the ER. Buoyant density analysis revealed that I853V/C2865F contributed to the release of virion with a density of ∼1.10 g/ml. Moreover, we demonstrated that NS5B directly interacted with NS2 at the protease domain and that mutations I853V, C2865F, and I853V/C2865F enhanced the interaction. In addition, C2865F also enhanced the interaction between NS5B and Core. In conclusion, this study demonstrated that adaptive mutations in NS2 and NS5B promoted HCV envelopment by accelerating Core translocation from the LDs to the ER and reinforced the interaction between NS2 and NS5B. The findings facilitate our understanding of the assembly of HCV morphogenesis.
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Affiliation(s)
- Fuxiang Zheng
- Institute of Human Virology, Zhongshan School of Medicine, and Key Laboratory of Tropical Disease Control of Ministry of Education, Sun Yat-sen University, Guangzhou, China
| | - Ni Li
- Institute of Human Virology, Zhongshan School of Medicine, and Key Laboratory of Tropical Disease Control of Ministry of Education, Sun Yat-sen University, Guangzhou, China
| | - Yi Xu
- Department of Pediatric, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, China
| | - Yuanping Zhou
- Department of Infectious Diseases, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Yi-Ping Li
- Institute of Human Virology, Zhongshan School of Medicine, and Key Laboratory of Tropical Disease Control of Ministry of Education, Sun Yat-sen University, Guangzhou, China; Department of Infectious Disease, The Fifth Affiliated Hospital of Sun Yat-sen University, Zhuhai, China.
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5
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Shimotohno K. HCV Assembly and Egress via Modifications in Host Lipid Metabolic Systems. Cold Spring Harb Perspect Med 2021; 11:cshperspect.a036814. [PMID: 32122916 PMCID: PMC7778218 DOI: 10.1101/cshperspect.a036814] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Hepatitis C virus (HCV) proliferates by hijacking the host lipid machinery. In vitro replication systems revealed many aspects of the virus life cycle; in particular, viral utilization of host lipid metabolism during HCV proliferation. HCV interacts with lipid droplets (LDs) before starting the process of virus capsid formation at the lipid-rich endoplasmic reticulum (ER) membrane compartment. HCV buds into the ER via lipoprotein assembly and secretion. Exchangeable apolipoproteins, represented by apolipoprotein E (apoE), play pivotal roles in enhancing HCV-specific infectivity. HCV virions are likely to interact with other lipoproteins circulating in blood vessels and incorporate apolipoproteins as well as lipids. This review focuses on virus assembly and egress by briefly describing the recent advances in this area.
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Vieyres G, Pietschmann T. HCV Pit Stop at the Lipid Droplet: Refuel Lipids and Put on a Lipoprotein Coat before Exit. Cells 2019; 8:cells8030233. [PMID: 30871009 PMCID: PMC6468556 DOI: 10.3390/cells8030233] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 02/28/2019] [Accepted: 03/04/2019] [Indexed: 02/07/2023] Open
Abstract
The replication cycle of the liver-tropic hepatitis C virus (HCV) is tightly connected to the host lipid metabolism, during the virus entry, replication, assembly and egress stages, but also while the virus circulates in the bloodstream. This interplay coins viral particle properties, governs viral cell tropism, and facilitates immune evasion. This review summarizes our knowledge of these interactions focusing on the late steps of the virus replication cycle. It builds on our understanding of the cell biology of lipid droplets and the biosynthesis of liver lipoproteins and attempts to explain how HCV hijacks these organelles and pathways to assemble its lipo-viro-particles. In particular, this review describes (i) the mechanisms of viral protein translocation to and from the lipid droplet surface and the orchestration of an interface between replication and assembly complexes, (ii) the importance of the triglyceride mobilization from the lipid droplets for HCV assembly, (iii) the interplay between HCV and the lipoprotein synthesis pathway including the role played by apolipoproteins in virion assembly, and finally (iv) the consequences of these complex virus–host interactions on the virion composition and its biophysical properties. The wealth of data accumulated in the past years on the role of the lipid metabolism in HCV assembly and its imprint on the virion properties will guide vaccine design efforts and reinforce our understanding of the hepatic lipid metabolism in health and disease.
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Affiliation(s)
- Gabrielle Vieyres
- Institute of Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research, a Joint Venture between the Medical School Hannover (MHH) and the Helmholtz Centre for Infection Research (HZI), 30625 Hannover, Germany.
| | - Thomas Pietschmann
- Institute of Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research, a Joint Venture between the Medical School Hannover (MHH) and the Helmholtz Centre for Infection Research (HZI), 30625 Hannover, Germany.
- German Centre for Infection Research (DZIF), Partner Site Hannover-Braunschweig, 38124 Braunschweig, Germany.
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7
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Roder AE, Vazquez C, Horner SM. The acidic domain of the hepatitis C virus NS4A protein is required for viral assembly and envelopment through interactions with the viral E1 glycoprotein. PLoS Pathog 2019; 15:e1007163. [PMID: 30730994 PMCID: PMC6382253 DOI: 10.1371/journal.ppat.1007163] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 02/20/2019] [Accepted: 01/05/2019] [Indexed: 02/07/2023] Open
Abstract
Hepatitis C virus (HCV) assembly and envelopment are coordinated by a complex protein interaction network that includes most of the viral structural and nonstructural proteins. While the nonstructural protein 4A (NS4A) is known to be important for viral particle production, the specific function of NS4A in this process is not well understood. We performed mutagenesis of the C-terminal acidic domain of NS4A and found that mutation of several of these amino acids prevented the formation of the viral envelope, and therefore the production of infectious virions, without affecting viral RNA replication. In an overexpression system, we found that NS4A interacted with several viral proteins known to coordinate envelopment, including the viral E1 glycoprotein. One of the NS4A C-terminal mutations, Y45F, disrupted the interaction of NS4A with E1. Specifically, NS4A interacted with the first hydrophobic region of E1, a region previously described as regulating viral particle production. Indeed, we found that an E1 mutation in this region, D72A, also disrupted the interaction of NS4A with E1. Supernatants from HCV NS4A Y45F transfected cells had significantly reduced levels of HCV RNA, however they contained equivalent levels of Core protein. Interestingly, the Core protein secreted from these cells formed high order oligomers with a density matching the infectious virus secreted from wild-type cells. These results suggest that this Y45F mutation in NS4A causes secretion of low-density Core particles lacking genomic HCV RNA. These results corroborate previous findings showing that the E1 D72A mutation also causes secretion of Core complexes lacking genomic HCV RNA, and therefore suggest that the interaction between NS4A and E1 is involved in the incorporation of viral RNA into infectious HCV particles. Our findings define a new role for NS4A in the HCV lifecycle and help elucidate the protein interactions necessary for production of infectious virus.
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Affiliation(s)
- Allison E Roder
- Department of Molecular Genetics & Microbiology, Duke University Medical Center, Durham, NC, United States of America
| | - Christine Vazquez
- Department of Molecular Genetics & Microbiology, Duke University Medical Center, Durham, NC, United States of America
| | - Stacy M Horner
- Department of Molecular Genetics & Microbiology, Duke University Medical Center, Durham, NC, United States of America
- Department of Medicine, Duke University Medical Center, Durham, NC, United States of America
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Alazard-Dany N, Denolly S, Boson B, Cosset FL. Overview of HCV Life Cycle with a Special Focus on Current and Possible Future Antiviral Targets. Viruses 2019; 11:v11010030. [PMID: 30621318 PMCID: PMC6356578 DOI: 10.3390/v11010030] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 12/31/2018] [Accepted: 01/02/2019] [Indexed: 12/12/2022] Open
Abstract
Hepatitis C infection is the leading cause of liver diseases worldwide and a major health concern that affects an estimated 3% of the global population. Novel therapies available since 2014 and 2017 are very efficient and the WHO considers HCV eradication possible by the year 2030. These treatments are based on the so-called direct acting antivirals (DAAs) that have been developed through research efforts by academia and industry since the 1990s. After a brief overview of the HCV life cycle, we describe here the functions of the different targets of current DAAs, the mode of action of these DAAs and potential future inhibitors.
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Affiliation(s)
- Nathalie Alazard-Dany
- CIRI-Centre International de Recherche en Infectiologie, Univ Lyon, Université Claude Bernard Lyon 1, Inserm, U1111, CNRS, UMR5308, ENS Lyon, F-69007 Lyon, France.
| | - Solène Denolly
- CIRI-Centre International de Recherche en Infectiologie, Univ Lyon, Université Claude Bernard Lyon 1, Inserm, U1111, CNRS, UMR5308, ENS Lyon, F-69007 Lyon, France.
| | - Bertrand Boson
- CIRI-Centre International de Recherche en Infectiologie, Univ Lyon, Université Claude Bernard Lyon 1, Inserm, U1111, CNRS, UMR5308, ENS Lyon, F-69007 Lyon, France.
| | - François-Loïc Cosset
- CIRI-Centre International de Recherche en Infectiologie, Univ Lyon, Université Claude Bernard Lyon 1, Inserm, U1111, CNRS, UMR5308, ENS Lyon, F-69007 Lyon, France.
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9
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Neuralized E3 Ubiquitin Protein Ligase 3 Is an Inducible Antiviral Effector That Inhibits Hepatitis C Virus Assembly by Targeting Viral E1 Glycoprotein. J Virol 2018; 92:JVI.01123-18. [PMID: 30111563 DOI: 10.1128/jvi.01123-18] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 08/08/2018] [Indexed: 12/14/2022] Open
Abstract
Hepatitis C virus (HCV) infection is a major cause of chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma. HCV can be sensed by host innate immunity to induce expression of interferons (IFNs) and a number of antiviral effectors. In this study, we found HCV infection induced the expression of neuralized E3 ubiquitin protein ligase 3 (NEURL3), a putative E3 ligase, in a manner that requires the involvement of innate immune sensing but is independent of the IFN action. Furthermore, we showed that NEURL3 inhibited HCV infection while it had little effect on other RNA viruses, including Zika virus (ZIKV), dengue virus (DENV), and vesicular stomatitis virus (VSV). Mechanistic studies demonstrated that NEURL3 inhibited HCV assembly by directly binding HCV envelope glycoprotein E1 to interfere with the E1/E2 heterodimerization, an important prerequisite for virion morphogenesis. Finally, we showed that knockout of NEURL3 significantly enhanced HCV infection. In summary, we identified NEURL3 as a novel inducible antiviral host factor that suppresses HCV assembly. Our results not only shed new insight into how host innate immunity acts against HCV but also revealed a new important biological function for NEURL3.IMPORTANCE The exact biological function of NEURL3, a putative E3 ligase, remains largely unknown. In this study, we found that NEURL3 could be upregulated upon HCV infection in a manner dependent on pattern recognition receptor-mediated innate immune response. NEURL3 inhibits HCV assembly by directly binding viral E1 envelope glycoprotein to disrupt its interaction with E2, an action that requires its Neuralized homology repeat (NHR) domain but not the RING domain. Furthermore, we found that NEURL3 has a pangenotypic anti-HCV activity and interacts with E1 of genotypes 2a, 1b, 3a, and 6a but does not inhibit other closely related RNA viruses, such as ZIKV, DENV, and VSV. To our knowledge, our study is the first report to demonstrate that NEURL3 functions as an antiviral host factor. Our results not only shed new insight into how host innate immunity acts against HCV, but also revealed a new important biological function for NEURL3.
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10
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Liang Y, Cao X, Ding Q, Zhao Y, He Z, Zhong J. Hepatitis C virus NS4B induces the degradation of TRIF to inhibit TLR3-mediated interferon signaling pathway. PLoS Pathog 2018; 14:e1007075. [PMID: 29782532 PMCID: PMC5983870 DOI: 10.1371/journal.ppat.1007075] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 06/01/2018] [Accepted: 05/07/2018] [Indexed: 12/12/2022] Open
Abstract
Toll-like receptor 3 (TLR3) senses dsRNA intermediates produced during RNA virus replication to activate innate immune signaling pathways through adaptor protein TRIF. Many viruses have evolved strategies to block TLR3-mediated interferon signaling via targeting TRIF. Here we studied how hepatitis C virus (HCV) antagonizes the TLR3-mediated interferon signaling. We found that HCV-encoded NS4B protein inhibited TLR3-mediated interferon signaling by down-regulating TRIF protein level. Mechanism studies indicated that the downregulation of TRIF by NS4B was dependent on caspase8. NS4B transfection or HCV infection can activate caspase8 to promote TRIF degradation, leading to suppression of TLR3-mediated interferon signaling. Knockout of caspase8 can prevent TRIF degradation triggered by NS4B, thereby enhancing the TLR3-mediated interferon signaling activation in response to HCV infection. In conclusion, our work revealed a new mechanism for HCV to evade innate immune response by blocking the TLR3-mediated interferon signaling via NS4B-induced TRIF degradation.
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Affiliation(s)
- Yisha Liang
- CAS Key Laboratory of Molecular Virology and Immunology, Unit of Viral Hepatitis, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China
- ShanghaiTech University, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Xuezhi Cao
- CAS Key Laboratory of Molecular Virology and Immunology, Unit of Viral Hepatitis, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China
| | - Qiang Ding
- CAS Key Laboratory of Molecular Virology and Immunology, Unit of Viral Hepatitis, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China
| | - Yanan Zhao
- CAS Key Laboratory of Molecular Virology and Immunology, Unit of Viral Hepatitis, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Zhenliang He
- CAS Key Laboratory of Molecular Virology and Immunology, Unit of Viral Hepatitis, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Jin Zhong
- CAS Key Laboratory of Molecular Virology and Immunology, Unit of Viral Hepatitis, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China
- ShanghaiTech University, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
- * E-mail:
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11
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Wang Q, Li Y, Liu SA, Xie W, Cheng J. Cell culture-adaptive mutations in hepatitis C virus promote viral production by enhancing viral replication and release. World J Gastroenterol 2018; 24:1299-1311. [PMID: 29599605 PMCID: PMC5871825 DOI: 10.3748/wjg.v24.i12.1299] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Revised: 01/04/2018] [Accepted: 01/18/2018] [Indexed: 02/06/2023] Open
Abstract
AIM To explore hepatitis C virus (HCV) adaptive mutations or combinations thereof responsible for enhanced viral production and investigate the underlying mechanisms.
METHODS A series of plasmids with adaptive mutations were constructed. After the plasmids were transfected into Huh7.5 cells, we determined the infectious HCV particle titers by NS5A immunofluorescence assays, and detected HCV RNA replication by real-time PCR and protein expression by Western blot. Then we carried out immunoblotting of supernatants and cell lysates with anti-NS3 to analyze the virus release level. In addition, co-localization of lipid droplets (LDs) with NS5A was measured using confocal laser scanning microscopy. The ratio between the p56 and p58 phosphoforms of NS5A was analyzed further.
RESULTS The plasmids named JFH1-mE2, JFH1-mp7, JFH1-mNS4B, JFH1-mNS5A, JFH1-mE2/NS5A, JFH1-mp7/NS5A, JFH1-mNS4B/NS5A, JFH1-mE2/p7/NS5A, and mJFH1 were constructed successfully. This study generated infectious HCV particles with a robust titer of 1.61 × 106 focus-forming units (FFUs)/mL. All of the six adaptive mutations increased the HCV particle production at varying levels. The NS5A (C2274R, I2340T, and V2440L) and p7 (H781Y) were critical adaptive mutations. The effect of NS5A (C2274R, I2340T, and V2440L), p7 (H781Y), and NS4B (N1931S) on infectious HCV titers was investigated by measuring the HCV RNA replication, protein expression, and virion release. However, the six adaptive mutations were not required for the LD localization of NS5A proteins or the phosphorylation of NS5A.
CONCLUSION In this study, we generated infectious HCV particles with a robust titer of 1.61 × 106 FFUs/mL, and found that the viral replication and release levels could be enhanced by some of the adaptive mutations.
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Affiliation(s)
- Qi Wang
- Center of Liver Diseases, Beijing Ditan Hospital, Capital Medical University, Beijing 100015, China
- Beijing Key Laboratory of Emerging Infectious Diseases, Beijing 100015, China
| | - Yue Li
- Department of Pathology, Beijing Ditan Hospital, Capital Medical University, Beijing 100015, China
| | - Shun-Ai Liu
- Institute of Infectious Diseases, Beijing Ditan Hospital, Capital Medical University, Beijing 100015, China
- Beijing Key Laboratory of Emerging Infectious Diseases, Beijing 100015, China
| | - Wen Xie
- Center of Liver Diseases, Beijing Ditan Hospital, Capital Medical University, Beijing 100015, China
| | - Jun Cheng
- Center of Liver Diseases, Beijing Ditan Hospital, Capital Medical University, Beijing 100015, China
- Institute of Infectious Diseases, Beijing Ditan Hospital, Capital Medical University, Beijing 100015, China
- Beijing Key Laboratory of Emerging Infectious Diseases, Beijing 100015, China
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12
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Lei X, Kou Y, Fu Y, Rajashekar N, Shi H, Wu F, Xu J, Luo Y, Chen L. The Cancer Mutation D83V Induces an α-Helix to β-Strand Conformation Switch in MEF2B. J Mol Biol 2018; 430:1157-1172. [PMID: 29477338 DOI: 10.1016/j.jmb.2018.02.012] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 02/13/2018] [Accepted: 02/17/2018] [Indexed: 12/29/2022]
Abstract
MEF2B is a major target of somatic mutations in non-Hodgkin lymphoma. Most of these mutations are non-synonymous substitutions of surface residues in the MADS-box/MEF2 domain. Among them, D83V is the most frequent mutation found in tumor cells. The link between this hotspot mutation and cancer is not well understood. Here we show that the D83V mutation induces a dramatic α-helix to β-strand switch in the MEF2 domain. Located in an α-helix region rich in β-branched residues, the D83V mutation not only removes the extensive helix stabilization interactions but also introduces an additional β-branched residue that further shifts the conformation equilibrium from α-helix to β-strand. Cross-database analyses of cancer mutations and chameleon sequences revealed a number of well-known cancer targets harboring β-strand favoring mutations in chameleon α-helices, suggesting a commonality of such conformational switch in certain cancers and a new factor to consider when stratifying the rapidly expanding cancer mutation data.
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Affiliation(s)
- Xiao Lei
- Molecular and Computational Biology, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Yi Kou
- Molecular and Computational Biology, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA; Department of Chemistry, University of Southern California, Los Angeles, CA 90089, USA; USC Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA
| | - Yang Fu
- Molecular and Computational Biology, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Niroop Rajashekar
- Molecular and Computational Biology, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Haoran Shi
- Molecular and Computational Biology, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Fang Wu
- Department of Statistics and Applied Probability, University of California, Santa Barbara, CA 93106, USA
| | - Jiang Xu
- Molecular and Computational Biology, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA; Department of Chemistry, University of Southern California, Los Angeles, CA 90089, USA; USC Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA
| | - Yibing Luo
- Department of Statistics, University of California, Davis, CA 95616, USA
| | - Lin Chen
- Molecular and Computational Biology, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA; Department of Chemistry, University of Southern California, Los Angeles, CA 90089, USA; USC Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA.
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13
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A role for domain I of the hepatitis C virus NS5A protein in virus assembly. PLoS Pathog 2018; 14:e1006834. [PMID: 29352312 PMCID: PMC5792032 DOI: 10.1371/journal.ppat.1006834] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 01/31/2018] [Accepted: 12/19/2017] [Indexed: 12/12/2022] Open
Abstract
The NS5A protein of hepatitis C virus (HCV) plays roles in both virus genome replication and assembly. NS5A comprises three domains, of these domain I is believed to be involved exclusively in genome replication. In contrast, domains II and III are required for the production of infectious virus particles and are largely dispensable for genome replication. Domain I is highly conserved between HCV and related hepaciviruses, and is highly structured, exhibiting different dimeric conformations. To investigate the functions of domain I in more detail, we conducted a mutagenic study of 12 absolutely conserved and surface-exposed residues within the context of a JFH-1-derived sub-genomic replicon and infectious virus. Whilst most of these abrogated genome replication, three mutants (P35A, V67A and P145A) retained the ability to replicate but showed defects in virus assembly. P35A exhibited a modest reduction in infectivity, however V67A and P145A produced no infectious virus. Using a combination of density gradient fractionation, biochemical analysis and high resolution confocal microscopy we demonstrate that V67A and P145A disrupted the localisation of NS5A to lipid droplets. In addition, the localisation and size of lipid droplets in cells infected with these two mutants were perturbed compared to wildtype HCV. Biophysical analysis revealed that V67A and P145A abrogated the ability of purified domain I to dimerize and resulted in an increased affinity of binding to HCV 3’UTR RNA. Taken together, we propose that domain I of NS5A plays multiple roles in assembly, binding nascent genomic RNA and transporting it to lipid droplets where it is transferred to Core. Domain I also contributes to a change in lipid droplet morphology, increasing their size. This study reveals novel functions of NS5A domain I in assembly of infectious HCV and provides new perspectives on the virus lifecycle. Hepatitis C virus infects 170 million people worldwide, causing long term liver disease. Recently new therapies comprising direct-acting antivirals (DAAs), small molecule inhibitors of virus proteins, have revolutionised treatment for infected patients. Despite this, we have a limited understanding of how the virus replicates in infected liver cells. Here we identify a previously uncharacterised function of the NS5A protein–a target for one class of DAAs. NS5A is comprised of three domains–we show that the first of these (domain I) plays a role in the production of new, infectious virus particles. Previously it was thought that domain I was only involved in replicating the virus genome. Mutations in domain I perturb dimer formation, enhanced binding to the 3’ end of the virus RNA genome and prevented NS5A from interacting with lipid droplets, cellular lipid storage organelles that are required for assembly of new viruses. We propose that domain I of NS5A plays multiple roles in virus assembly. As domain I is the putative target for one class of DAAs, our observations may have implications for the as yet undefined mode of action of these compounds.
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Denolly S, Mialon C, Bourlet T, Amirache F, Penin F, Lindenbach B, Boson B, Cosset FL. The amino-terminus of the hepatitis C virus (HCV) p7 viroporin and its cleavage from glycoprotein E2-p7 precursor determine specific infectivity and secretion levels of HCV particle types. PLoS Pathog 2017; 13:e1006774. [PMID: 29253880 PMCID: PMC5749900 DOI: 10.1371/journal.ppat.1006774] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 01/02/2018] [Accepted: 11/27/2017] [Indexed: 12/18/2022] Open
Abstract
Viroporins are small transmembrane proteins with ion channel activities modulating properties of intracellular membranes that have diverse proviral functions. Hepatitis C virus (HCV) encodes a viroporin, p7, acting during assembly, envelopment and secretion of viral particles (VP). HCV p7 is released from the viral polyprotein through cleavage at E2-p7 and p7-NS2 junctions by signal peptidase, but also exists as an E2p7 precursor, of poorly defined properties. Here, we found that ectopic p7 expression in HCVcc-infected cells reduced secretion of particle-associated E2 glycoproteins. Using biochemical assays, we show that p7 dose-dependently slows down the ER-to-Golgi traffic, leading to intracellular retention of E2, which suggested that timely E2p7 cleavage and p7 liberation are critical events to control E2 levels. By studying HCV mutants with accelerated E2p7 processing, we demonstrate that E2p7 cleavage controls E2 intracellular expression and secretion levels of nucleocapsid-free subviral particles and infectious virions. In addition, our imaging data reveal that, following p7 liberation, the amino-terminus of p7 is exposed towards the cytosol and coordinates the encounter between NS5A and NS2-based assembly sites loaded with E1E2 glycoproteins, which subsequently leads to nucleocapsid envelopment. We identify punctual mutants at p7 membrane interface that, by abrogating NS2/NS5A interaction, are defective for transmission of infectivity owing to decreased secretion of core and RNA and to increased secretion of non/partially-enveloped particles. Altogether, our results indicate that the retarded E2p7 precursor cleavage is essential to regulate the intracellular and secreted levels of E2 through p7-mediated modulation of the cell secretory pathway and to unmask critical novel assembly functions located at p7 amino-terminus.
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Affiliation(s)
- Solène Denolly
- CIRI–International Center for Infectiology Research, Team EVIR, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, Ecole Normale Supérieure de Lyon, Univ Lyon, Lyon, France
| | - Chloé Mialon
- CIRI–International Center for Infectiology Research, Team EVIR, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, Ecole Normale Supérieure de Lyon, Univ Lyon, Lyon, France
| | - Thomas Bourlet
- GIMAP, EA 3064, Faculté de Médecine, Université de Saint-Etienne, Univ Lyon, Saint Etienne, France
| | - Fouzia Amirache
- CIRI–International Center for Infectiology Research, Team EVIR, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, Ecole Normale Supérieure de Lyon, Univ Lyon, Lyon, France
| | - François Penin
- IBCP—Institut de Biologie et Chimie des Protéines, MMSB, UMR 5086, CNRS, Univ Lyon, Lyon, France
| | - Brett Lindenbach
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, CT, United States of America
| | - Bertrand Boson
- CIRI–International Center for Infectiology Research, Team EVIR, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, Ecole Normale Supérieure de Lyon, Univ Lyon, Lyon, France
| | - François-Loïc Cosset
- CIRI–International Center for Infectiology Research, Team EVIR, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, Ecole Normale Supérieure de Lyon, Univ Lyon, Lyon, France
- * E-mail:
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