1
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Gargan S, Stevenson NJ. Unravelling the Immunomodulatory Effects of Viral Ion Channels, towards the Treatment of Disease. Viruses 2021; 13:2165. [PMID: 34834972 PMCID: PMC8618147 DOI: 10.3390/v13112165] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 09/07/2021] [Accepted: 10/10/2021] [Indexed: 02/07/2023] Open
Abstract
The current COVID-19 pandemic has highlighted the need for the research community to develop a better understanding of viruses, in particular their modes of infection and replicative lifecycles, to aid in the development of novel vaccines and much needed anti-viral therapeutics. Several viruses express proteins capable of forming pores in host cellular membranes, termed "Viroporins". They are a family of small hydrophobic proteins, with at least one amphipathic domain, which characteristically form oligomeric structures with central hydrophilic domains. Consequently, they can facilitate the transport of ions through the hydrophilic core. Viroporins localise to host membranes such as the endoplasmic reticulum and regulate ion homeostasis creating a favourable environment for viral infection. Viroporins also contribute to viral immune evasion via several mechanisms. Given that viroporins are often essential for virion assembly and egress, and as their structural features tend to be evolutionarily conserved, they are attractive targets for anti-viral therapeutics. This review discusses the current knowledge of several viroporins, namely Influenza A virus (IAV) M2, Human Immunodeficiency Virus (HIV)-1 Viral protein U (Vpu), Hepatitis C Virus (HCV) p7, Human Papillomavirus (HPV)-16 E5, Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV) Open Reading Frame (ORF)3a and Polyomavirus agnoprotein. We highlight the intricate but broad immunomodulatory effects of these viroporins and discuss the current antiviral therapies that target them; continually highlighting the need for future investigations to focus on novel therapeutics in the treatment of existing and future emergent viruses.
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Affiliation(s)
- Siobhan Gargan
- Viral Immunology Group, School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, D02 R590 Dublin, Ireland;
| | - Nigel J. Stevenson
- Viral Immunology Group, School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, D02 R590 Dublin, Ireland;
- Viral Immunology Group, Royal College of Surgeons in Ireland-Medical University of Bahrain, Manama 15503, Bahrain
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2
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Shaw J, Gosain R, Kalita MM, Foster TL, Kankanala J, Mahato DR, Abas S, King BJ, Scott C, Brown E, Bentham MJ, Wetherill L, Bloy A, Samson A, Harris M, Mankouri J, Rowlands DJ, Macdonald A, Tarr AW, Fischer WB, Foster R, Griffin S. Rationally derived inhibitors of hepatitis C virus (HCV) p7 channel activity reveal prospect for bimodal antiviral therapy. eLife 2020; 9:e52555. [PMID: 33169665 PMCID: PMC7714397 DOI: 10.7554/elife.52555] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 11/09/2020] [Indexed: 12/26/2022] Open
Abstract
Since the 1960s, a single class of agent has been licensed targeting virus-encoded ion channels, or 'viroporins', contrasting the success of channel blocking drugs in other areas of medicine. Although resistance arose to these prototypic adamantane inhibitors of the influenza A virus (IAV) M2 proton channel, a growing number of clinically and economically important viruses are now recognised to encode essential viroporins providing potential targets for modern drug discovery. We describe the first rationally designed viroporin inhibitor with a comprehensive structure-activity relationship (SAR). This step-change in understanding not only revealed a second biological function for the p7 viroporin from hepatitis C virus (HCV) during virus entry, but also enabled the synthesis of a labelled tool compound that retained biological activity. Hence, p7 inhibitors (p7i) represent a unique class of HCV antiviral targeting both the spread and establishment of infection, as well as a precedent for future viroporin-targeted drug discovery.
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Affiliation(s)
- Joseph Shaw
- Leeds Institute of Medical Research, School of Medicine, Faculty of Medicine and Health, University of Leeds, St James’ University HospitalLeedsUnited Kingdom
- Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse LaneLeedsUnited Kingdom
| | - Rajendra Gosain
- Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse LaneLeedsUnited Kingdom
- School of Chemistry, University of Leeds, Woodhouse LaneLeedsUnited Kingdom
| | - Monoj Mon Kalita
- Institute of Biophotonics, National Yang-Ming UniversityTaipeiTaiwan
| | - Toshana L Foster
- Leeds Institute of Medical Research, School of Medicine, Faculty of Medicine and Health, University of Leeds, St James’ University HospitalLeedsUnited Kingdom
- Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse LaneLeedsUnited Kingdom
| | - Jayakanth Kankanala
- Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse LaneLeedsUnited Kingdom
- School of Chemistry, University of Leeds, Woodhouse LaneLeedsUnited Kingdom
| | - D Ram Mahato
- Institute of Biophotonics, National Yang-Ming UniversityTaipeiTaiwan
| | - Sonia Abas
- Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse LaneLeedsUnited Kingdom
- School of Chemistry, University of Leeds, Woodhouse LaneLeedsUnited Kingdom
| | - Barnabas J King
- School of Life Sciences, Faculty of Medicine & Health Sciences, University of Nottingham, Queen's Medical CentreNottinghamUnited Kingdom
| | - Claire Scott
- Leeds Institute of Medical Research, School of Medicine, Faculty of Medicine and Health, University of Leeds, St James’ University HospitalLeedsUnited Kingdom
- Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse LaneLeedsUnited Kingdom
| | - Emma Brown
- Leeds Institute of Medical Research, School of Medicine, Faculty of Medicine and Health, University of Leeds, St James’ University HospitalLeedsUnited Kingdom
- Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse LaneLeedsUnited Kingdom
| | - Matthew J Bentham
- Leeds Institute of Medical Research, School of Medicine, Faculty of Medicine and Health, University of Leeds, St James’ University HospitalLeedsUnited Kingdom
- Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse LaneLeedsUnited Kingdom
| | - Laura Wetherill
- Leeds Institute of Medical Research, School of Medicine, Faculty of Medicine and Health, University of Leeds, St James’ University HospitalLeedsUnited Kingdom
- Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse LaneLeedsUnited Kingdom
| | - Abigail Bloy
- Leeds Institute of Medical Research, School of Medicine, Faculty of Medicine and Health, University of Leeds, St James’ University HospitalLeedsUnited Kingdom
- Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse LaneLeedsUnited Kingdom
| | - Adel Samson
- Leeds Institute of Medical Research, School of Medicine, Faculty of Medicine and Health, University of Leeds, St James’ University HospitalLeedsUnited Kingdom
| | - Mark Harris
- Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse LaneLeedsUnited Kingdom
- School of Molecular & Cellular Biology, Faculty of Biological Sciences, University of Leeds, Woodhouse LaneLeedsUnited Kingdom
| | - Jamel Mankouri
- Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse LaneLeedsUnited Kingdom
- School of Molecular & Cellular Biology, Faculty of Biological Sciences, University of Leeds, Woodhouse LaneLeedsUnited Kingdom
| | - David J Rowlands
- Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse LaneLeedsUnited Kingdom
- School of Molecular & Cellular Biology, Faculty of Biological Sciences, University of Leeds, Woodhouse LaneLeedsUnited Kingdom
| | - Andrew Macdonald
- Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse LaneLeedsUnited Kingdom
- School of Molecular & Cellular Biology, Faculty of Biological Sciences, University of Leeds, Woodhouse LaneLeedsUnited Kingdom
| | - Alexander W Tarr
- School of Life Sciences, Faculty of Medicine & Health Sciences, University of Nottingham, Queen's Medical CentreNottinghamUnited Kingdom
| | | | - Richard Foster
- Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse LaneLeedsUnited Kingdom
- School of Chemistry, University of Leeds, Woodhouse LaneLeedsUnited Kingdom
| | - Stephen Griffin
- Leeds Institute of Medical Research, School of Medicine, Faculty of Medicine and Health, University of Leeds, St James’ University HospitalLeedsUnited Kingdom
- Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse LaneLeedsUnited Kingdom
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3
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Alzahrani N, Wu MJ, Shanmugam S, Yi M. Delayed by Design: Role of Suboptimal Signal Peptidase Processing of Viral Structural Protein Precursors in Flaviviridae Virus Assembly. Viruses 2020; 12:v12101090. [PMID: 32993149 PMCID: PMC7601889 DOI: 10.3390/v12101090] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 09/04/2020] [Accepted: 09/24/2020] [Indexed: 02/06/2023] Open
Abstract
The Flaviviridae virus family is classified into four different genera, including flavivirus, hepacivirus, pegivirus, and pestivirus, which cause significant morbidity and mortality in humans and other mammals, including ruminants and pigs. These are enveloped, single-stranded RNA viruses sharing a similar genome organization and replication scheme with certain unique features that differentiate them. All viruses in this family express a single polyprotein that encodes structural and nonstructural proteins at the N- and C-terminal regions, respectively. In general, the host signal peptidase cleaves the structural protein junction sites, while virus-encoded proteases process the nonstructural polyprotein region. It is known that signal peptidase processing is a rapid, co-translational event. Interestingly, certain signal peptidase processing site(s) in different Flaviviridae viral structural protein precursors display suboptimal cleavage kinetics. This review focuses on the recent progress regarding the Flaviviridae virus genus-specific mechanisms to downregulate signal peptidase-mediated processing at particular viral polyprotein junction sites and the role of delayed processing at these sites in infectious virus particle assembly.
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4
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Dearborn AD, Marcotrigiano J. Hepatitis C Virus Structure: Defined by What It Is Not. Cold Spring Harb Perspect Med 2020; 10:cshperspect.a036822. [PMID: 31501263 DOI: 10.1101/cshperspect.a036822] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Hepatitis C virus (HCV) represents an important and growing public health problem, chronically infecting an estimated 70 million people worldwide. This blood-borne pathogen is generating a new wave of infections in the United States, associated with increasing intravenous drug use over the last decade. In most cases, HCV establishes a chronic infection, sometimes causing cirrhosis, end-stage liver disease, and hepatocellular carcinoma. Although a curative therapy exists, it is extremely expensive and provides no barrier to reinfection; therefore, a vaccine is urgently needed. The virion is asymmetric and heterogeneous with the buoyancy and protein content similar to low-density lipoparticles. Core protein is unstructured, and of the two envelope glycoproteins, E1 and E2, the function of E1 remains enigmatic. E2 is responsible for specifically binding host receptors CD81 and scavenger receptor class B type I (SR-BI). This review will focus on structural progress on HCV virion, core protein, envelope glycoproteins, and specific host receptors.
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Affiliation(s)
- Altaira D Dearborn
- The Protein Expression Laboratory, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.,Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Joseph Marcotrigiano
- The Protein Expression Laboratory, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
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5
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Abstract
Maintenance of the main Golgi functions, glycosylation and sorting, is dependent on the unique Golgi pH microenvironment that is thought to be set by the balance between the rates of V-ATPase-mediated proton pumping and its leakage back to the cytoplasm via an unknown pathway. The concentration of other ions, such as chloride, potassium, calcium, magnesium, and manganese, is also important for Golgi homeostasis and dependent on the transport activity of other ion transporters present in the Golgi membranes. During the last decade, several new disorders have been identified that are caused by, or are associated with, dysregulated Golgi pH and ion homeostasis. Here, we will provide an updated overview on these disorders and the proteins involved. We will also discuss other disorders for which the molecular defects remain currently uncertain but which potentially involve proteins that regulate Golgi pH or ion homeostasis.
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6
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Soares HR, Ferreira-Fernandes M, Almeida AI, Marchel M, Alves PM, Coroadinha AS. Enhancing Hepatitis C virus pseudoparticles infectivity through p7NS2 cellular expression. J Virol Methods 2019; 274:113714. [PMID: 31412271 DOI: 10.1016/j.jviromet.2019.113714] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 07/30/2019] [Accepted: 08/09/2019] [Indexed: 12/27/2022]
Abstract
Hepatitis C pseudoparticles (HCVpp) are used to evaluate HCV cell entry while screening for neutralizing antibodies induced upon vaccination or while screening for new antiviral drugs. In this work we explore the stable production of HCVpp aiming to reduce the variability associated with transient productions. The performance of stably produced HCVpp was assessed by evaluating the influence of Human Serum and the impact of CD81 cellular expression on the infectivity of HCVpp. After evaluating the performance of stably produced HCVpp we studied the effect of co-expressing p7NS2 openreading frame (ORF) on HCVpp infectivity. Our data clearly shows an enhanced infectivity of HCVppp7NS2. Even though the exact mechanism was not completely elucidated, the enhanced infectivity of HCVppp7NS2 is neither a result of an increase production of virus particles nor a result from increased envelope density. The inhibitory effect of p7 inhibitory molecules such as rimantadine suggests a direct contribution of p7 ion channel for the enhanced infectivity of HCVppp7NS2 which is coherent with a pH-dependent cell entry mechanism. In conclusion, we report the establishment of a stable production system of HCVpp with enhanced infectivity through the overexpression of p7NS2 ORF contributing to improve HCV entry assessment assays widely used in antiviral drug discovery and vaccine development.
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Affiliation(s)
- Hugo R Soares
- iBET, Instituto de Biologia Experimental e Tecnológica, Apartado 12, 2780-901 Oeiras, Portugal; Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157 Oeiras, Portugal
| | - Marina Ferreira-Fernandes
- iBET, Instituto de Biologia Experimental e Tecnológica, Apartado 12, 2780-901 Oeiras, Portugal; Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157 Oeiras, Portugal
| | - Ana I Almeida
- iBET, Instituto de Biologia Experimental e Tecnológica, Apartado 12, 2780-901 Oeiras, Portugal; Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157 Oeiras, Portugal
| | - Mateusz Marchel
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157 Oeiras, Portugal; Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Avenida Rovisco Pais, 1049-001 Lisboa, Portugal
| | - Paula M Alves
- iBET, Instituto de Biologia Experimental e Tecnológica, Apartado 12, 2780-901 Oeiras, Portugal; Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157 Oeiras, Portugal
| | - Ana S Coroadinha
- iBET, Instituto de Biologia Experimental e Tecnológica, Apartado 12, 2780-901 Oeiras, Portugal; Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157 Oeiras, Portugal.
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7
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Oestringer BP, Bolivar JH, Claridge JK, Almanea L, Chipot C, Dehez F, Holzmann N, Schnell JR, Zitzmann N. Hepatitis C virus sequence divergence preserves p7 viroporin structural and dynamic features. Sci Rep 2019; 9:8383. [PMID: 31182749 PMCID: PMC6557816 DOI: 10.1038/s41598-019-44413-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 05/10/2019] [Indexed: 12/31/2022] Open
Abstract
The hepatitis C virus (HCV) viroporin p7 oligomerizes to form ion channels, which are required for the assembly and secretion of infectious viruses. The 63-amino acid p7 monomer has two putative transmembrane domains connected by a cytosolic loop, and has both N- and C- termini exposed to the endoplasmic reticulum (ER) lumen. NMR studies have indicated differences between p7 structures of distantly related HCV genotypes. A critical question is whether these differences arise from the high sequence variation between the different isolates and if so, how the divergent structures can support similar biological functions. Here, we present a side-by-side characterization of p7 derived from genotype 1b (isolate J4) in the detergent 6-cyclohexyl-1-hexylphosphocholine (Cyclofos-6) and p7 derived from genotype 5a (isolate EUH1480) in n-dodecylphosphocholine (DPC). The 5a isolate p7 in conditions previously associated with a disputed oligomeric form exhibits secondary structure, dynamics, and solvent accessibility broadly like those of the monomeric 1b isolate p7. The largest differences occur at the start of the second transmembrane domain, which is destabilized in the 5a isolate. The results show a broad consensus among the p7 variants that have been studied under a range of different conditions and indicate that distantly related HCVs preserve key features of structure and dynamics.
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Affiliation(s)
- Benjamin P Oestringer
- Oxford Glycobiology Institute, Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, United Kingdom.,Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, United Kingdom.,Immunocore Limited, 101 Park Drive, Milton Park, Abingdon, Oxon, OX14 4RY, United Kingdom
| | - Juan H Bolivar
- Oxford Glycobiology Institute, Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, United Kingdom
| | - Jolyon K Claridge
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, United Kingdom.,Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, 1050, Brussels, Belgium.,Structural and Molecular Microbiology, Structural Biology Research Center, VIB, Pleinlaan 2, 1050, Brussels, Belgium
| | - Latifah Almanea
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, United Kingdom
| | - Chris Chipot
- Laboratoire International Associé CNRS-University of Illinois at Urbana Champaign, Université de Lorraine, BP 70239, 54506, Vandœuvre-lès-Nancy, France.,Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, Illinois, 61801, United States
| | - François Dehez
- Laboratoire International Associé CNRS-University of Illinois at Urbana Champaign, Université de Lorraine, BP 70239, 54506, Vandœuvre-lès-Nancy, France
| | - Nicole Holzmann
- Laboratoire International Associé CNRS-University of Illinois at Urbana Champaign, Université de Lorraine, BP 70239, 54506, Vandœuvre-lès-Nancy, France
| | - Jason R Schnell
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, United Kingdom.
| | - Nicole Zitzmann
- Oxford Glycobiology Institute, Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, United Kingdom.
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8
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Convery O, Gargan S, Kickham M, Schroder M, O'Farrelly C, Stevenson NJ. The hepatitis C virus (HCV) protein, p7, suppresses inflammatory responses to tumor necrosis factor (TNF)-α via signal transducer and activator of transcription (STAT)3 and extracellular signal-regulated kinase (ERK)-mediated induction of suppressor of cytokine signaling (SOCS)3. FASEB J 2019; 33:8732-8744. [PMID: 31163989 DOI: 10.1096/fj.201800629rr] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Viruses use a spectrum of immune evasion strategies that enable infection and replication. The acute phase of hepatitis C virus (HCV) infection is characterized by nonspecific and often mild clinical symptoms, suggesting an immunosuppressive mechanism that, unless symptomatic liver disease presents, allows the virus to remain largely undetected. We previously reported that HCV induced the regulatory protein suppressor of cytokine signaling (SOCS)3, which inhibited TNF-α-mediated inflammatory responses. However, the mechanism by which HCV up-regulates SOCS3 remains unknown. Here we show that the HCV protein, p7, enhances both SOCS3 mRNA and protein expression. A p7 inhibitor reduced SOCS3 induction, indicating that p7's ion channel activity was required for optimal up-regulation of SOCS3. Short hairpin RNA and chemical inhibition revealed that both the Janus kinase-signal transducer and activator of transcription (JAK-STAT) and MAPK pathways were required for p7-mediated induction of SOCS3. HCV-p7 expression suppressed TNF-α-mediated IκB-α degradation and subsequent NF-κB promoter activity, revealing a new and functional, anti-inflammatory effect of p7. Together, these findings identify a molecular mechanism by which HCV-p7 induces SOCS3 through STAT3 and ERK activation and demonstrate that p7 suppresses proinflammatory responses to TNF-α, possibly explaining the lack of inflammatory symptoms observed during early HCV infection.-Convery, O., Gargan, S., Kickham, M., Schroder, M., O'Farrelly, C., Stevenson, N. J. The hepatitis C virus (HCV) protein, p7, suppresses inflammatory responses to tumor necrosis factor (TNF)-α via signal transducer and activator of transcription (STAT)3 and extracellular signal-regulated kinase (ERK)-mediated induction of suppressor of cytokine signaling (SOCS)3.
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Affiliation(s)
- Orla Convery
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, Ireland
| | - Siobhan Gargan
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, Ireland
| | | | | | - Cliona O'Farrelly
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, Ireland.,School of Medicine, Trinity College Dublin, Dublin, Ireland
| | - Nigel J Stevenson
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, Ireland
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9
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Westerbeck JW, Machamer CE. The Infectious Bronchitis Coronavirus Envelope Protein Alters Golgi pH To Protect the Spike Protein and Promote the Release of Infectious Virus. J Virol 2019; 93:e00015-19. [PMID: 30867314 PMCID: PMC6532078 DOI: 10.1128/jvi.00015-19] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Accepted: 03/07/2019] [Indexed: 12/20/2022] Open
Abstract
Coronaviruses (CoVs) assemble by budding into the lumen of the early Golgi complex prior to exocytosis. The small CoV envelope (E) protein plays roles in assembly, virion release, and pathogenesis. CoV E has a single hydrophobic domain (HD), is targeted to Golgi membranes, and has cation channel activity in vitro The E protein from avian infectious bronchitis virus (IBV) has dramatic effects on the secretory system, which require residues in the HD. Mutation of the HD of IBV E in a recombinant virus background results in impaired growth kinetics, impaired release of infectious virions, accumulation of IBV spike (S) protein on the plasma membrane compared to wild-type (WT) IBV-infected cells, and aberrant cleavage of IBV S on virions. We previously reported the formation of two distinct oligomeric pools of IBV E in transfected and infected cells. Disruption of the secretory pathway by IBV E correlates with a form that is likely monomeric, suggesting that the effects on the secretory pathway are independent of E ion channel activity. Here, we present evidence suggesting that the monomeric form of IBV E correlates with an increased Golgi luminal pH. Infection with IBV or expression of IBV E induces neutralization of Golgi pH, promoting a model in which IBV E alters the secretory pathway through interaction with host cell factors, protecting IBV S from premature cleavage and leading to the efficient release of infectious virus from the cells. This is the first demonstration of a coronavirus-induced alteration in the microenvironment of the secretory pathway.IMPORTANCE Coronaviruses are important human pathogens with significant zoonotic potential. Progress has been made toward identifying potential vaccine candidates for highly pathogenic human CoVs, including the use of attenuated viruses that lack the CoV E protein or express E mutants. However, no approved vaccines or antiviral therapeutics exist. Understanding the role of the CoV E protein in virus assembly and release is thus an important prerequisite for potential vaccines as well as in identifying novel antiviral therapeutics.
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Affiliation(s)
- Jason W Westerbeck
- Department of Cell Biology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Carolyn E Machamer
- Department of Cell Biology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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10
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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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11
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Duan X, Anwar MI, Xu Z, Ma L, Yuan G, Chen Y, Liu X, Xia J, Zhou Y, Li YP. Adaptive mutation F772S-enhanced p7-NS4A cooperation facilitates the assembly and release of hepatitis C virus and is associated with lipid droplet enlargement. Emerg Microbes Infect 2018; 7:143. [PMID: 30087320 PMCID: PMC6081454 DOI: 10.1038/s41426-018-0140-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Revised: 06/17/2018] [Accepted: 06/23/2018] [Indexed: 12/20/2022]
Abstract
Hepatitis C virus (HCV) infection is a major cause of chronic hepatitis and liver cancer worldwide. Adaptive mutations play important roles in the development of the HCV replicon and its infectious clones. We and others have previously identified the p7 mutation F772S and the co-presence of NS4A mutations in infectious HCV full-length clones and chimeric recombinants. However, the underlying mechanism of F772S function remains incompletely understood. Here, we investigated the functional role of F772S using an efficient JFH1-based reporter virus with Core-NS2 from genotype 2a strain J6, and we designated J6-p7/JFH1-4A according to the strain origin of the p7 and NS4A sequences. We found that replacing JFH1-4A with J6-4A (wild-type or mutated NS4A) or genotype 2b J8-4A severely attenuated the viability of J6-p7/JFH1-4A. However, passage-recovered viruses that contained J6-p7 all acquired F772S. Introduction of F772S efficiently rescued the viral spread and infectivity titers of J6-p7/J6-4A, which reached the levels of the original J6-p7/JFH1-4A and led to a concomitant increase in RNA replication, assembly and release of viruses with J6-specific p7 and NS4A. These data suggest that an isolate-specific cooperation existed between p7 and NS4A. NS4A exchange- or substitution-mediated viral attenuation was attributed to the RNA sequence, and no p7-NS4A protein interaction was detected. Moreover, we found that F772S-enhanced p7-NS4A cooperation was associated with the enlargement of intracellular lipid droplets. This study therefore provides new insights into the mechanisms of adaptive mutations and facilitates studies on the HCV life cycle and virus–host interaction.
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Affiliation(s)
- Xiaobing Duan
- Institute of Human Virology and Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, 501180, China.,Key Laboratory of Tropical Disease Control of Ministry of Education, Sun Yat-Sen University, Guangzhou, 501180, China.,Guangdong Engineering Research Center for Antimicrobial Agent and Immunotechnology, Sun Yat-Sen University, Guangzhou, 510080, China
| | - Muhammad Ikram Anwar
- Institute of Human Virology and Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, 501180, China.,Key Laboratory of Tropical Disease Control of Ministry of Education, Sun Yat-Sen University, Guangzhou, 501180, China.,Guangdong Engineering Research Center for Antimicrobial Agent and Immunotechnology, Sun Yat-Sen University, Guangzhou, 510080, China
| | - Zhanxue Xu
- Institute of Human Virology and Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, 501180, China.,Key Laboratory of Tropical Disease Control of Ministry of Education, Sun Yat-Sen University, Guangzhou, 501180, China.,Guangdong Engineering Research Center for Antimicrobial Agent and Immunotechnology, Sun Yat-Sen University, Guangzhou, 510080, China
| | - Ling Ma
- Institute of Human Virology and Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, 501180, China.,Key Laboratory of Tropical Disease Control of Ministry of Education, Sun Yat-Sen University, Guangzhou, 501180, China.,Guangdong Engineering Research Center for Antimicrobial Agent and Immunotechnology, Sun Yat-Sen University, Guangzhou, 510080, China
| | - Guosheng Yuan
- Department of Infectious Diseases, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China
| | - Yiyi Chen
- Institute of Human Virology and Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, 501180, China.,Key Laboratory of Tropical Disease Control of Ministry of Education, Sun Yat-Sen University, Guangzhou, 501180, China.,Guangdong Engineering Research Center for Antimicrobial Agent and Immunotechnology, Sun Yat-Sen University, Guangzhou, 510080, China
| | - Xi Liu
- Department of Infectious Diseases, The Fifth Affiliated Hospital of Sun Yat-sen University, Zhuhai, 519000, China
| | - Jinyu Xia
- Department of Infectious Diseases, The Fifth Affiliated Hospital of Sun Yat-sen University, Zhuhai, 519000, China
| | - Yuanping Zhou
- Department of Infectious Diseases, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China
| | - Yi-Ping Li
- Institute of Human Virology and Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, 501180, China. .,Key Laboratory of Tropical Disease Control of Ministry of Education, Sun Yat-Sen University, Guangzhou, 501180, China. .,Guangdong Engineering Research Center for Antimicrobial Agent and Immunotechnology, Sun Yat-Sen University, Guangzhou, 510080, China. .,Program in Pathobiology, The Fifth Affiliated Hospital and Zhongshan School of Medicine, Sun Yat-sen University, Zhuhai, 519000, China.
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12
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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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13
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Too IHK, Yeo H, Sessions OM, Yan B, Libau EA, Howe JLC, Lim ZQ, Suku-Maran S, Ong WY, Chua KB, Wong BS, Chow VTK, Alonso S. Enterovirus 71 infection of motor neuron-like NSC-34 cells undergoes a non-lytic exit pathway. Sci Rep 2016; 6:36983. [PMID: 27849036 PMCID: PMC5111112 DOI: 10.1038/srep36983] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Accepted: 10/20/2016] [Indexed: 01/08/2023] Open
Abstract
Enterovirus 71 (EV71) causing Hand, Foot and Mouth Disease, is regarded as the most important neurotropic virus worldwide. EV71 is believed to replicate in muscles and infect motor neurons to reach the central nervous system (CNS). To further investigate the mechanisms involved, we have employed the motor neuron cell line NSC-34. NSC-34 cells were permissive to EV71 and virus production yields were strain-dependent with differential efficacy at the entry, replication and egress steps. Furthermore, unlike all the other cell lines previously reported, EV71-infected NSC-34 cells neither displayed cytopathic effect nor underwent apoptosis. Instead, autophagy was markedly up-regulated and virus-containing autophagic vacuoles were isolated from the culture supernatant, providing the first experimental evidence that EV71 can adopt a non-lytic exit pathway. Finally, the ability of EV71 to infect productively NSC-34 cells correlated with its ability to invade the CNS in vivo, supporting the relevance of NSC-34 cells to study the intrinsic neurovirulence of EV71 strains.
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Affiliation(s)
- Issac Horng Khit Too
- Department of Microbiology &Immunology, Yong Loo Lin School of Medicine, National University of Singapore, 117456, Singapore.,Immunology Programme, Life Sciences Institute, CeLS building, 28 Medical Drive, National University of Singapore, 117456, Singapore
| | - Huimin Yeo
- Department of Microbiology &Immunology, Yong Loo Lin School of Medicine, National University of Singapore, 117456, Singapore.,Immunology Programme, Life Sciences Institute, CeLS building, 28 Medical Drive, National University of Singapore, 117456, Singapore
| | - October Michael Sessions
- Program in Emerging Infectious Diseases, Duke-NUS Graduate Medical School, 8 College Road, 169857, Singapore
| | - Benedict Yan
- Department of Laboratory Medicine, 5 Lower Kent Ridge Road, National University Hospital, 119074, Singapore
| | - Eshele Anak Libau
- Department of Microbiology &Immunology, Yong Loo Lin School of Medicine, National University of Singapore, 117456, Singapore.,Immunology Programme, Life Sciences Institute, CeLS building, 28 Medical Drive, National University of Singapore, 117456, Singapore
| | - Josephine L C Howe
- Department of Microbiology &Immunology, Yong Loo Lin School of Medicine, National University of Singapore, 117456, Singapore
| | - Ze Qin Lim
- Department of Microbiology &Immunology, Yong Loo Lin School of Medicine, National University of Singapore, 117456, Singapore.,Immunology Programme, Life Sciences Institute, CeLS building, 28 Medical Drive, National University of Singapore, 117456, Singapore
| | - Shalini Suku-Maran
- Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, 117456, Singapore.,Neurobiology and Ageing Programme, Life Sciences Institute, CeLS building, 28 Medical Drive, National University of Singapore, 117456, Singapore
| | - Wei-Yi Ong
- Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, 117456, Singapore.,Neurobiology and Ageing Programme, Life Sciences Institute, CeLS building, 28 Medical Drive, National University of Singapore, 117456, Singapore
| | - Kaw Bing Chua
- Temasek Life Sciences Laboratory, 5 A Engineering Drive 1, National University of Singapore, 117411, Singapore
| | - Boon Seng Wong
- Neurobiology and Ageing Programme, Life Sciences Institute, CeLS building, 28 Medical Drive, National University of Singapore, 117456, Singapore.,Department of Physiology, Yong Loo Lin School of Medicine, CeLS building, 28 Medical Drive, National University of Singapore, 117456, Singapore
| | - Vincent T K Chow
- Department of Microbiology &Immunology, Yong Loo Lin School of Medicine, National University of Singapore, 117456, Singapore
| | - Sylvie Alonso
- Department of Microbiology &Immunology, Yong Loo Lin School of Medicine, National University of Singapore, 117456, Singapore.,Immunology Programme, Life Sciences Institute, CeLS building, 28 Medical Drive, National University of Singapore, 117456, Singapore
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14
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Laasch N, Kalita MM, Griffin S, Fischer WB. Small molecule ligand docking to genotype specific bundle structures of hepatitis C virus (HCV) p7 protein. Comput Biol Chem 2016; 64:56-63. [PMID: 27258799 DOI: 10.1016/j.compbiolchem.2016.04.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Accepted: 04/28/2016] [Indexed: 01/26/2023]
Abstract
The genome of hepatitis C virus encodes for an essential 63 amino acid polytopic protein p7 of most likely two transmembrane domains (TMDs). The protein is identified to self-assemble thereby rendering lipid membranes permeable to ions. A series of small molecules such as adamantanes, imino sugars and guanidinium compounds are known to interact with p7. A set of 9 of these small molecules is docked against hexameric bundles of genotypes 5a (bundle-5a) and 1b (bundle-1b) using LeadIT. Putative sites for bundle-5a are identified within the pore and at pockets on the outside of the bundle. For bundle-1b preferred sites are found at the site of the loops. Binding energies are in favour of the guanidinium compounds. Rescoring of the identified poses with HYDE reveals a dehydration penalty for the guanidinium compounds, leaving the adamantanes and imino sugar in a better position. Binding energies calculated by HYDE and those by LeadIT indicate that all compounds are moderate binders.
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Affiliation(s)
- Niklas Laasch
- Institute of Biophotonics, School of Biomedical Science and Engineering, and Biophotonics & Molecular Imaging Research Center (BMIRC), National Yang-Ming University, Taipei 112, Taiwan
| | - Monoj Mon Kalita
- Institute of Biophotonics, School of Biomedical Science and Engineering, and Biophotonics & Molecular Imaging Research Center (BMIRC), National Yang-Ming University, Taipei 112, Taiwan
| | - Stephen Griffin
- Institute of Biophotonics, School of Biomedical Science and Engineering, and Biophotonics & Molecular Imaging Research Center (BMIRC), National Yang-Ming University, Taipei 112, Taiwan
| | - Wolfgang B Fischer
- Institute of Biophotonics, School of Biomedical Science and Engineering, and Biophotonics & Molecular Imaging Research Center (BMIRC), National Yang-Ming University, Taipei 112, Taiwan.
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15
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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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16
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Structural and Functional Properties of the Hepatitis C Virus p7 Viroporin. Viruses 2015; 7:4461-81. [PMID: 26258788 PMCID: PMC4576187 DOI: 10.3390/v7082826] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Revised: 07/28/2015] [Accepted: 07/30/2015] [Indexed: 12/13/2022] Open
Abstract
The high prevalence of hepatitis C virus (HCV) infection in the human population has triggered intensive research efforts that have led to the development of curative antiviral therapy. Moreover, HCV has become a role model to study fundamental principles that govern the replication cycle of a positive strand RNA virus. In fact, for most HCV proteins high-resolution X-ray and NMR (Nuclear Magnetic Resonance)-based structures have been established and profound insights into their biochemical and biological properties have been gained. One example is p7, a small hydrophobic protein that is dispensable for RNA replication, but crucial for the production and release of infectious HCV particles from infected cells. Owing to its ability to insert into membranes and assemble into homo-oligomeric complexes that function as minimalistic ion channels, HCV p7 is a member of the viroporin family. This review compiles the most recent findings related to the structure and dual pore/ion channel activity of p7 of different HCV genotypes. The alternative conformations and topologies proposed for HCV p7 in its monomeric and oligomeric state are described and discussed in detail. We also summarize the different roles p7 might play in the HCV replication cycle and highlight both the ion channel/pore-like function and the additional roles of p7 unrelated to its channel activity. Finally, we discuss possibilities to utilize viroporin inhibitors for antagonizing p7 ion channel/pore-like activity.
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17
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Scott C, Griffin S. Viroporins: structure, function and potential as antiviral targets. J Gen Virol 2015; 96:2000-2027. [PMID: 26023149 DOI: 10.1099/vir.0.000201] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The channel-forming activity of a family of small, hydrophobic integral membrane proteins termed 'viroporins' is essential to the life cycles of an increasingly diverse range of RNA and DNA viruses, generating significant interest in targeting these proteins for antiviral development. Viroporins vary greatly in terms of their atomic structure and can perform multiple functions during the virus life cycle, including those distinct from their role as oligomeric membrane channels. Recent progress has seen an explosion in both the identification and understanding of many such proteins encoded by highly significant pathogens, yet the prototypic M2 proton channel of influenza A virus remains the only example of a viroporin with provenance as an antiviral drug target. This review attempts to summarize our current understanding of the channel-forming functions for key members of this growing family, including recent progress in structural studies and drug discovery research, as well as novel insights into the life cycles of many viruses revealed by a requirement for viroporin activity. Ultimately, given the successes of drugs targeting ion channels in other areas of medicine, unlocking the therapeutic potential of viroporins represents a valuable goal for many of the most significant viral challenges to human and animal health.
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Affiliation(s)
- Claire Scott
- Leeds Institute of Cancer & Pathology and Leeds CRUK Clinical Centre, Faculty of Medicine and Health, St James's University Hospital, University of Leeds, Beckett Street, Leeds LS9 7TF, UK
| | - Stephen Griffin
- Leeds Institute of Cancer & Pathology and Leeds CRUK Clinical Centre, Faculty of Medicine and Health, St James's University Hospital, University of Leeds, Beckett Street, Leeds LS9 7TF, UK
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18
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Lin Z, Liang W, Kang K, Li H, Cao Z, Zhang Y. Classical swine fever virus and p7 protein induce secretion of IL-1β in macrophages. J Gen Virol 2014; 95:2693-2699. [PMID: 25146005 DOI: 10.1099/vir.0.068502-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Classical swine fever virus (CSFV) has a tropism for vascular endothelial cells and immune system cells. The process and release of pro-inflammatory cytokines, including IL-1β and IL-18, is one of the fundamental reactions of the innate immune response to viral infection. In this study, we investigated the production of IL-1β from macrophages following CSFV infection. Our results showed that IL-1β was upregulated after CSFV infection through activating caspase-1. Subsequent studies demonstrated that reactive oxygen species may not be involved in CSFV-mediated IL-1β release. Recently, research has indicated a novel mechanism by which inflammasomes are triggered through detection of activity of viroporin. We further demonstrated that CSFV viroporin p7 protein induced IL-1β secretion which could be inhibited by the ion channel blocker amantadine and also discovered that p7 protein was a short-lived protein degraded by the proteasome. Together, our observations provided an insight into the mechanism of CSFV-induced inflammatory responses.
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Affiliation(s)
- Zhi Lin
- College of Veterinary Medicine, Northwest A & F University, Yangling 712100, Shaanxi, PR China
| | - Wulong Liang
- College of Veterinary Medicine, Northwest A & F University, Yangling 712100, Shaanxi, PR China
| | - Kai Kang
- College of Veterinary Medicine, Northwest A & F University, Yangling 712100, Shaanxi, PR China
| | - Helin Li
- College of Veterinary Medicine, Northwest A & F University, Yangling 712100, Shaanxi, PR China
| | - Zhi Cao
- College of Veterinary Medicine, Northwest A & F University, Yangling 712100, Shaanxi, PR China
| | - Yanming Zhang
- College of Veterinary Medicine, Northwest A & F University, Yangling 712100, Shaanxi, PR China
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19
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Bentham MJ, Marraiki N, McCormick CJ, Rowlands DJ, Griffin S. NS2 is dispensable for efficient assembly of hepatitis C virus-like particles in a bipartite trans-encapsidation system. J Gen Virol 2014; 95:2427-2441. [PMID: 25024280 PMCID: PMC4202265 DOI: 10.1099/vir.0.068932-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Infectious hepatitis C virus (HCV) particle production in the genotype 2a JFH-1-based cell culture system involves non-structural proteins in addition to canonical virion components. NS2 has been proposed to act as a protein adaptor, co-ordinating the early stages of virion assembly. However, other studies have identified late-acting roles for this protein, making its precise involvement in infectious particle production unclear. Using a robust, bipartite trans-encapsidation system based upon baculovirus expression of HCV structural proteins, we have generated HCV-like particles (HCV-LP) in the absence of NS2 with overt similarity to wild-type virions. HCV-LP could transduce naive cells with trans-encapsidated subgenomic replicon RNAs and shared similar biochemical and biophysical properties with JFH-1 HCV. Both genotype 1b and JFH-1 intracellular HCV-LP were produced in the absence of NS2, whereas restoring NS2 to the JFH-1 system dramatically enhanced secreted infectivity, consistent with a late-acting role. Our system recapitulated authentic HCV particle assembly via trans-complementation of bicistronic, NS2-deleted, chimeric HCV, which is otherwise deficient in particle production. This closely resembled replicon-mediated NS2 trans-complementation, confirming that baculovirus expression of HCV proteins did not unduly affect particle production. Furthermore, this suggests that separation of structural protein expression from replicating HCV RNAs that are destined to be packaged alleviates an early stage requirement for NS2 during particle formation. This highlights our current lack of understanding of how NS2 mediates assembly, yet comparison of full-length and bipartite systems may provide further insight into this process.
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Affiliation(s)
- Matthew J Bentham
- Leeds Institute of Cancer & Pathology (LICAP), and Leeds CRUK Clinical Centre, Faculty of Medicine and Health, St James's University Hospital, University of Leeds, Beckett St., Leeds, West Yorkshire LS9 7TF, UK
| | - Najat Marraiki
- School of Molecular & Cellular Biology and Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Mount Preston Street, Leeds, West Yorkshire LS2 9JT, UK
| | - Christopher J McCormick
- Faculty of Medicine, University of Southampton, Southampton General Hospital, Tremona Road, Southampton SO16 6YD, UK
| | - David J Rowlands
- School of Molecular & Cellular Biology and Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Mount Preston Street, Leeds, West Yorkshire LS2 9JT, UK
| | - Stephen Griffin
- School of Molecular & Cellular Biology and Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Mount Preston Street, Leeds, West Yorkshire LS2 9JT, UK.,Leeds Institute of Cancer & Pathology (LICAP), and Leeds CRUK Clinical Centre, Faculty of Medicine and Health, St James's University Hospital, University of Leeds, Beckett St., Leeds, West Yorkshire LS9 7TF, UK
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20
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Atoom AM, Taylor NGA, Russell RS. The elusive function of the hepatitis C virus p7 protein. Virology 2014; 462-463:377-87. [PMID: 25001174 PMCID: PMC7112009 DOI: 10.1016/j.virol.2014.04.018] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 04/07/2014] [Accepted: 04/11/2014] [Indexed: 12/12/2022]
Abstract
Hepatitis C virus (HCV) is a major global health burden with 2–3% of the world׳s population being chronically infected. Persistent infection can lead to cirrhosis and hepatocellular carcinoma. Recently available treatment options show enhanced efficacy of virus clearance, but are associated with resistance and significant side effects. This warrants further research into the basic understanding of viral proteins and their pathophysiology. The p7 protein of HCV is an integral membrane protein that forms an ion-channel. The role of p7 in the HCV life cycle is presently uncertain, but most of the research performed to date highlights its role in the virus assembly process. The aim of this review is to provide an overview of the literature investigating p7, its structural and functional details, and to summarize the developments to date regarding potential anti-p7 compounds. A better understanding of this protein may lead to development of a new and effective therapy. This review paper provides an overview of the literature investigating HCV. The content focuses on p7 structural and functional details. We summarize the developments to date regarding potential anti-p7 compounds.
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Affiliation(s)
- Ali M Atoom
- Division of BioMedical Sciences, Faculty of Medicine, Memorial University, Newfoundland, St. John׳s, Canada
| | - Nathan G A Taylor
- Division of BioMedical Sciences, Faculty of Medicine, Memorial University, Newfoundland, St. John׳s, Canada
| | - Rodney S Russell
- Division of BioMedical Sciences, Faculty of Medicine, Memorial University, Newfoundland, St. John׳s, Canada.
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21
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Hagen N, Bayer K, Rösch K, Schindler M. The intraviral protein interaction network of hepatitis C virus. Mol Cell Proteomics 2014; 13:1676-89. [PMID: 24797426 DOI: 10.1074/mcp.m113.036301] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Hepatitis C virus (HCV) is a global health problem and one of the main reasons for chronic liver diseases such as cirrhosis and hepatocellular carcinoma. The HCV genome is translated into a polyprotein which is proteolytically processed into 10 viral proteins. The interactome of the HCV proteins with the host cell has been worked out; however, it remains unclear how viral proteins interact with each other. We aimed to generate the interaction network of these 10 HCV proteins using a flow-cytometry-based FRET assay established in our laboratory (Banning, C., Votteler, J., Hoffmann, D., Koppensteiner, H., Warmer, M., Reimer, R., Kirchhoff, F., Schubert, U., Hauber, J., and Schindler, M. (2010) A flow cytometry-based FRET assay to identify and analyse protein-protein interactions in living cells. PLoS One 5, e9344). HCV proteins were constructed as fusions with the chromophores CFP and YFP. All HCV fusions were expressed and localized to specific subcellular compartments, indicating that they were functional. FACS-FRET measurements identified a total of 20 interactions; 13 of these were previously described and have now been confirmed in living cells via our method. Among the seven novel protein binding pairs, HCV p7 plays a pivotal role. It binds to the HCV capsid protein Core and the two glycoproteins E1 and E2. These interplays were further demonstrated in the relevant context of Huh7.5 liver cells expressing infectious HCV. Our work demonstrates the feasibility of rapidly generating small interaction networks via FACS-FRET and defines the network of intra-HCV protein interactions. Furthermore, our data support an important role of p7 in HCV assembly.
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Affiliation(s)
- Nicole Hagen
- From the ‡Heinrich Pette Institute, Leibniz Institute for Experimental Virology, 20251 Hamburg, Germany
| | - Karen Bayer
- ¶Institute of Virology, Helmholtz Zentrum Munich, German Research Center for Environmental Health, 85764 Neuherberg, Germany
| | - Kathrin Rösch
- From the ‡Heinrich Pette Institute, Leibniz Institute for Experimental Virology, 20251 Hamburg, Germany
| | - Michael Schindler
- From the ‡Heinrich Pette Institute, Leibniz Institute for Experimental Virology, 20251 Hamburg, Germany; ¶Institute of Virology, Helmholtz Zentrum Munich, German Research Center for Environmental Health, 85764 Neuherberg, Germany; ‖Institute of Medical Virology and Epidemiology of Viral Diseases, University Clinic Tübingen, 72076 Tübingen, Germany
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22
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Atkins E, Tatineni R, Li H, Gretch D, Harris M, Griffin S. The stability of secreted, acid-labile H77/JFH-1 hepatitis C virus (HCV) particles is altered by patient isolate genotype 1a p7 sequences. Virology 2014; 448:117-24. [PMID: 24314642 PMCID: PMC7615703 DOI: 10.1016/j.virol.2013.10.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Revised: 09/05/2013] [Accepted: 10/03/2013] [Indexed: 12/17/2022]
Abstract
Secreted infectious particles generated by the genotype 2a JFH-1 hepatitis C virus infectious clone are resistant to acidic pH, whereas intracellular virions remain acid-labile. Thus, JFH-1 particles are thought to undergo pH maturation as they are secreted from the cell. Here, we demonstrate that both infectious intracellular and secreted genotype 1a (H77)/JFH-1 chimaeric particles display enhanced acid sensitivity compared with JFH-1, although pH maturation still occurs upon release. Introduction of p7 sequences from genotype 1a infected HCV patients into the H77/JFH-1 background yielded variable effects on infectious particle production and sensitivity to small molecule inhibitors. However, two selected patient p7 sequences increased the acid stability of secreted, but not intracellular H77/JFH-1 particles, suggesting that p7 directly influences particle pH maturation via an as yet undefined mechanism. We propose that HCV particles vary in acid stability, and that this may be dictated by variations in both canonical structural proteins and p7.
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Affiliation(s)
- Elizabeth Atkins
- School of Molecular & Cellular Biology & Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, West Yorkshire LS2 9JT, United Kingdom
| | - Ranjitha Tatineni
- Leeds Institute of Cancer & Pathology (LICAP) and Leeds Cancer Research UK Clinical Centre, Faculty of Medicine and Health, St James’ University Hospital, University of Leeds, Beckett St., Leeds, West Yorkshire LS9 7TF, United Kingdom
| | - Hui Li
- Department of Laboratory Medicine, University of Washington School of Medicine, Harborview Medical Centre, Ninth & Jefferson Building, 908 Jefferson Street, Seattle, WA 98104, USA
| | - David Gretch
- Department of Laboratory Medicine, University of Washington School of Medicine, Harborview Medical Centre, Ninth & Jefferson Building, 908 Jefferson Street, Seattle, WA 98104, USA
| | - Mark Harris
- School of Molecular & Cellular Biology & Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, West Yorkshire LS2 9JT, United Kingdom
| | - Stephen Griffin
- School of Molecular & Cellular Biology & Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, West Yorkshire LS2 9JT, United Kingdom
- Leeds Institute of Cancer & Pathology (LICAP) and Leeds Cancer Research UK Clinical Centre, Faculty of Medicine and Health, St James’ University Hospital, University of Leeds, Beckett St., Leeds, West Yorkshire LS9 7TF, United Kingdom
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