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Hsia JZ, Liu D, Haynes L, Cruz-Cosme R, Tang Q. Lipid Droplets: Formation, Degradation, and Their Role in Cellular Responses to Flavivirus Infections. Microorganisms 2024; 12:647. [PMID: 38674592 PMCID: PMC11051834 DOI: 10.3390/microorganisms12040647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Revised: 03/18/2024] [Accepted: 03/22/2024] [Indexed: 04/28/2024] Open
Abstract
Lipid droplets (LDs) are cellular organelles derived from the endoplasmic reticulum (ER), serving as lipid storage sites crucial for maintaining cellular lipid homeostasis. Recent attention has been drawn to their roles in viral replication and their interactions with viruses. However, the precise biological functions of LDs in viral replication and pathogenesis remain incompletely understood. To elucidate the interaction between LDs and viruses, it is imperative to comprehend the biogenesis of LDs and their dynamic interactions with other organelles. In this review, we explore the intricate pathways involved in LD biogenies within the cytoplasm, encompassing the uptake of fatty acid from nutrients facilitated by CD36-mediated membranous protein (FABP/FATP)-FA complexes, and FA synthesis via glycolysis in the cytoplasm and the TCL cycle in mitochondria. While LD biogenesis primarily occurs in the ER, matured LDs are intricately linked to multiple organelles. Viral infections can lead to diverse consequences in terms of LD status within cells post-infection, potentially involving the breakdown of LDs through the activation of lipophagy. However, the exact mechanisms underlying LD destruction or accumulation by viruses remain elusive. The significance of LDs in viral replication renders them effective targets for developing broad-spectrum antivirals. Moreover, considering that reducing neutral lipids in LDs is a strategy for anti-obesity treatment, LD depletion may not pose harm to cells. This presents LDs as promising antiviral targets for developing therapeutics that are minimally or non-toxic to the host.
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Affiliation(s)
| | | | | | | | - Qiyi Tang
- Department of Microbiology, Howard University College of Medicine, Washington, DC 20059, USA; (J.Z.H.); (D.L.); (L.H.); (R.C.-C.)
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2
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Matthaei A, Joecks S, Frauenstein A, Bruening J, Bankwitz D, Friesland M, Gerold G, Vieyres G, Kaderali L, Meissner F, Pietschmann T. Landscape of protein-protein interactions during hepatitis C virus assembly and release. Microbiol Spectr 2024; 12:e0256222. [PMID: 38230952 PMCID: PMC10846047 DOI: 10.1128/spectrum.02562-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Accepted: 10/11/2023] [Indexed: 01/18/2024] Open
Abstract
Assembly of infectious hepatitis C virus (HCV) particles requires multiple cellular proteins including for instance apolipoprotein E (ApoE). To describe these protein-protein interactions, we performed an affinity purification mass spectrometry screen of HCV-infected cells. We used functional viral constructs with epitope-tagged envelope protein 2 (E2), protein (p) 7, or nonstructural protein 4B (NS4B) as well as cells expressing a tagged variant of ApoE. We also evaluated assembly stage-dependent remodeling of protein complexes by using viral mutants carrying point mutations abrogating particle production at distinct steps of the HCV particle production cascade. Five ApoE binding proteins, 12 p7 binders, 7 primary E2 interactors, and 24 proteins interacting with NS4B were detected. Cell-derived PREB, STT3B, and SPCS2 as well as viral NS2 interacted with both p7 and E2. Only GTF3C3 interacted with E2 and NS4B, highlighting that HCV assembly and replication complexes exhibit largely distinct interactomes. An HCV core protein mutation, preventing core protein decoration of lipid droplets, profoundly altered the E2 interactome. In cells replicating this mutant, E2 interactions with HSPA5, STT3A/B, RAD23A/B, and ZNF860 were significantly enhanced, suggesting that E2 protein interactions partly depend on core protein functions. Bioinformatic and functional studies including STRING network analyses, RNA interference, and ectopic expression support a role of Rad23A and Rad23B in facilitating HCV infectious virus production. Both Rad23A and Rad23B are involved in the endoplasmic reticulum (ER)-associated protein degradation (ERAD). Collectively, our results provide a map of host proteins interacting with HCV assembly proteins, and they give evidence for the involvement of ER protein folding machineries and the ERAD pathway in the late stages of the HCV replication cycle.IMPORTANCEHepatitis C virus (HCV) establishes chronic infections in the majority of exposed individuals. This capacity likely depends on viral immune evasion strategies. One feature likely contributing to persistence is the formation of so-called lipo-viro particles. These peculiar virions consist of viral structural proteins and cellular lipids and lipoproteins, the latter of which aid in viral attachment and cell entry and likely antibody escape. To learn about how lipo-viro particles are coined, here, we provide a comprehensive overview of protein-protein interactions in virus-producing cells. We identify numerous novel and specific HCV E2, p7, and cellular apolipoprotein E-interacting proteins. Pathway analyses of these interactors show that proteins participating in processes such as endoplasmic reticulum (ER) protein folding, ER-associated protein degradation, and glycosylation are heavily engaged in virus production. Moreover, we find that the proteome of HCV replication sites is distinct from the assembly proteome, suggesting that transport process likely shuttles viral RNA to assembly sites.
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Affiliation(s)
- Alina Matthaei
- Institute of Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research, Hannover, Lower Saxony, Germany
| | - Sebastian Joecks
- Institute of Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research, Hannover, Lower Saxony, Germany
| | - Annika Frauenstein
- RG Experimental Systems Immunology, Max-Planck Institute for Biochemistry, Planegg, Bavaria, Germany
| | - Janina Bruening
- Institute of Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research, Hannover, Lower Saxony, Germany
| | - Dorothea Bankwitz
- Institute of Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research, Hannover, Lower Saxony, Germany
| | - Martina Friesland
- Institute of Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research, Hannover, Lower Saxony, Germany
| | - Gisa Gerold
- Institute of Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research, Hannover, Lower Saxony, Germany
- Department of Biochemistry & Research Center for Emerging Infections and Zoonoses (RIZ), University of Veterinary Medicine Hannover, Hannover, Lower Saxony, Germany
- Department of Clinical Microbiology, Virology, Umeå University, Umeå, Sweden
- Wallenberg Centre for Molecular Medicine (WCMM), Umeå University, Umeå, Sweden
| | - Gabrielle Vieyres
- Institute of Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research, Hannover, Lower Saxony, Germany
- Junior Research Group “Cell Biology of RNA Viruses,” Leibniz Institute of Experimental Virology, Hamburg, Germany
| | - Lars Kaderali
- Institute of Bioinformatics, University Medicine Greifswald, Greifswald, Germany
| | - Felix Meissner
- RG Experimental Systems Immunology, Max-Planck Institute for Biochemistry, Planegg, Bavaria, Germany
- Systems Immunology and Proteomics, Institute of Innate Immunity, Medical Faculty, University of Bonn, Bonn, Germany
| | - Thomas Pietschmann
- Institute of Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research, Hannover, Lower Saxony, Germany
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3
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Izumida K, Hara Y, Furukawa Y, Ishida K, Tabata K, Morita E. Purification of hepatitis C virus core protein in non-denaturing condition. J Virol Methods 2024; 323:114852. [PMID: 37979698 DOI: 10.1016/j.jviromet.2023.114852] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 11/08/2023] [Accepted: 11/10/2023] [Indexed: 11/20/2023]
Abstract
Hepatitis C virus (HCV) is the major cause of chronic hepatitis and hepatocellular carcinoma. Among its structural proteins, the HCV core protein has been implicated in liver disease. Understanding the role of HCV core proteins in viral diseases is crucial to elucidating disease mechanisms and identifying potential drug targets. However, purification challenges hinder the comprehensive elucidation of the structure and biochemical properties of HCV core proteins. In this study, we successfully solubilized bacterially expressed core protein using a high-salt and detergent-containing buffer and bypassed the denaturing-refolding process. Size-exclusion chromatography revealed three distinct peaks in the HCV-infected cell lysate, with the bacterially expressed soluble core protein corresponding to its second peak. Using a combination of affinity, size exclusion, and multi-modal chromatography purification techniques, we achieved a purity of > 95% for the core protein. Analytical ultracentrifugation revealed monomer formation in the solution. Far UV Circular dichroism spectroscopy identified 25.53% alpha helices and 20.26% beta sheets. These findings strongly suggest that the purified core proteins retained one of the native structures observed in HCV-infected cells.
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Affiliation(s)
- Kyo Izumida
- Laboratory of Viral Infection, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan
| | - Yumiko Hara
- Laboratory of Viral Infection, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan; Department of Biochemistry and Molecular Biology, Faculty of Agriculture and Life Science, Hirosaki University, Japan
| | - Yukio Furukawa
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadoaka, Suita, Osaka 565-0871, Japan
| | - Kotaro Ishida
- Department of Biochemistry and Molecular Biology, Faculty of Agriculture and Life Science, Hirosaki University, Japan
| | - Keisuke Tabata
- Laboratory of Viral Infection, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan; Laboratory of Intracellular Membrane Dynamics, Graduate School of Frontier Biosciences Osaka University, Osaka 565-0871, Japan; Department of Genetics, Graduate School of Medicine Osaka University, Osaka 565-0871, Japan
| | - Eiji Morita
- Laboratory of Viral Infection, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan; Department of Biochemistry and Molecular Biology, Faculty of Agriculture and Life Science, Hirosaki University, Japan.
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4
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Dempsey JL, Ioannou GN, Carr RM. Mechanisms of Lipid Droplet Accumulation in Steatotic Liver Diseases. Semin Liver Dis 2023; 43:367-382. [PMID: 37799111 DOI: 10.1055/a-2186-3557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/07/2023]
Abstract
The steatotic diseases of metabolic dysfunction-associated steatotic liver disease (MASLD), alcohol-associated liver disease (ALD), and chronic hepatitis C (HCV) account for the majority of liver disease prevalence, morbidity, and mortality worldwide. While these diseases have distinct pathogenic and clinical features, dysregulated lipid droplet (LD) organelle biology represents a convergence of pathogenesis in all three. With increasing understanding of hepatocyte LD biology, we now understand the roles of LD proteins involved in these diseases but also how genetics modulate LD biology to either exacerbate or protect against the phenotypes associated with steatotic liver diseases. Here, we review the history of the LD organelle and its biogenesis and catabolism. We also review how this organelle is critical not only for the steatotic phenotype of liver diseases but also for their advanced phenotypes. Finally, we summarize the latest attempts and challenges of leveraging LD biology for therapeutic gain in steatotic diseases. In conclusion, the study of dysregulated LD biology may lead to novel therapeutics for the prevention of disease progression in the highly prevalent steatotic liver diseases of MASLD, ALD, and HCV.
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Affiliation(s)
- Joseph L Dempsey
- Division of Gastroenterology, Department of Medicine, School of Medicine, University of Washington, Seattle, Washington
| | - George N Ioannou
- Division of Gastroenterology, Department of Medicine, School of Medicine, University of Washington, Seattle, Washington
- Division of Gastroenterology, Veterans Affairs Puget Sound Healthcare System Seattle, Washington
| | - Rotonya M Carr
- Division of Gastroenterology, Department of Medicine, School of Medicine, University of Washington, Seattle, Washington
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5
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Qu Y, Wang W, Xiao MZX, Zheng Y, Liang Q. The interplay between lipid droplets and virus infection. J Med Virol 2023; 95:e28967. [PMID: 37496184 DOI: 10.1002/jmv.28967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 07/06/2023] [Accepted: 07/07/2023] [Indexed: 07/28/2023]
Abstract
As an intracellular parasite, the virus usurps cellular machinery and modulates cellular metabolism pathways to replicate itself in cells. Lipid droplets (LDs) are universally conserved energy storage organelles that not only play vital roles in maintaining lipid homeostasis but are also involved in viral replication. Increasing evidence has demonstrated that viruses take advantage of cellular lipid metabolism by targeting the biogenesis, hydrolysis, and lipophagy of LD during viral infection. In this review, we summarize the current knowledge about the modulation of cellular LD by different viruses, with a special emphasis on the Hepatitis C virus, Dengue virus, and SARS-CoV-2.
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Affiliation(s)
- Yafei Qu
- Center for Immune-Related Diseases at Shanghai Institute of Immunology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Department of Immunology and Microbiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Weili Wang
- Center for Immune-Related Diseases at Shanghai Institute of Immunology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Department of Immunology and Microbiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Maggie Z X Xiao
- Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Yuejuan Zheng
- The Research Center for Traditional Chinese Medicine, Shanghai Institute of Infectious Disease and Biosecurity, Shanghai University of Traditional Medicine, Shanghai, China
- Center for Traditional Chinese Medicine and Immunology Research, School of Basic Medical Sciences, Shanghai University of Traditional Medicine, Shanghai, China
| | - Qiming Liang
- Center for Immune-Related Diseases at Shanghai Institute of Immunology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Department of Immunology and Microbiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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6
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Diaz O, Vidalain PO, Ramière C, Lotteau V, Perrin-Cocon L. What role for cellular metabolism in the control of hepatitis viruses? Front Immunol 2022; 13:1033314. [PMID: 36466918 PMCID: PMC9713817 DOI: 10.3389/fimmu.2022.1033314] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Accepted: 11/02/2022] [Indexed: 11/26/2023] Open
Abstract
Hepatitis B, C and D viruses (HBV, HCV, HDV, respectively) specifically infect human hepatocytes and often establish chronic viral infections of the liver, thus escaping antiviral immunity for years. Like other viruses, hepatitis viruses rely on the cellular machinery to meet their energy and metabolite requirements for replication. Although this was initially considered passive parasitism, studies have shown that hepatitis viruses actively rewire cellular metabolism through molecular interactions with specific enzymes such as glucokinase, the first rate-limiting enzyme of glycolysis. As part of research efforts in the field of immunometabolism, it has also been shown that metabolic changes induced by viruses could have a direct impact on the innate antiviral response. Conversely, detection of viral components by innate immunity receptors not only triggers the activation of the antiviral defense but also induces in-depth metabolic reprogramming that is essential to support immunological functions. Altogether, these complex triangular interactions between viral components, innate immunity and hepatocyte metabolism may explain why chronic hepatitis infections progressively lead to liver inflammation and progression to cirrhosis, fibrosis and hepatocellular carcinoma (HCC). In this manuscript, we first present a global overview of known connections between the innate antiviral response and cellular metabolism. We then report known molecular mechanisms by which hepatitis viruses interfere with cellular metabolism in hepatocytes and discuss potential consequences on the innate immune response. Finally, we present evidence that drugs targeting hepatocyte metabolism could be used as an innovative strategy not only to deprive viruses of key metabolites, but also to restore the innate antiviral response that is necessary to clear infection.
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Affiliation(s)
- Olivier Diaz
- CIRI, Centre International de Recherche en Infectiologie, Team VIRal Infection, Metabolism and Immunity, Univ Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, ENS de Lyon, Lyon, France
| | - Pierre-Olivier Vidalain
- CIRI, Centre International de Recherche en Infectiologie, Team VIRal Infection, Metabolism and Immunity, Univ Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, ENS de Lyon, Lyon, France
| | - Christophe Ramière
- CIRI, Centre International de Recherche en Infectiologie, Team VIRal Infection, Metabolism and Immunity, Univ Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, ENS de Lyon, Lyon, France
- Laboratoire de Virologie, Hôpital de la Croix-Rousse, Hospices Civils de Lyon, Lyon, France
| | - Vincent Lotteau
- CIRI, Centre International de Recherche en Infectiologie, Team VIRal Infection, Metabolism and Immunity, Univ Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, ENS de Lyon, Lyon, France
| | - Laure Perrin-Cocon
- CIRI, Centre International de Recherche en Infectiologie, Team VIRal Infection, Metabolism and Immunity, Univ Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, ENS de Lyon, Lyon, France
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7
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Devi P, Punga T, Bergqvist A. Activation of the Ca2+/NFAT Pathway by Assembly of Hepatitis C Virus Core Protein into Nucleocapsid-like Particles. Viruses 2022; 14:v14040761. [PMID: 35458491 PMCID: PMC9031069 DOI: 10.3390/v14040761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 03/31/2022] [Accepted: 04/03/2022] [Indexed: 02/05/2023] Open
Abstract
Hepatitis C virus (HCV) is the primary pathogen responsible for liver cirrhosis and hepatocellular carcinoma. The main virion component, the core (C) protein, has been linked to several aspects of HCV pathology, including oncogenesis, immune evasion and stress responses. We and others have previously shown that C expression in various cell lines activates Ca2+ signaling and alters Ca2+ homeostasis. In this study, we identified two distinct C protein regions that are required for the activation of Ca2+/NFAT signaling. In the basic N-terminal domain, which has been implicated in self-association of C, amino acids 1–68 were critical for NFAT activation. Sedimentation analysis of four mutants in this domain revealed that association of the C protein into nucleocapsid-like particles correlated with NFAT-activated transcription. The internal, lipid droplet-targeting domain was not required for NFAT-activated transcription. Finally, the C-terminal ER-targeting domain was required in extenso for the C protein to function. Our results indicate that targeting of HCV C to the ER is necessary but not sufficient for inducing Ca2+/NFAT signaling. Taken together, our data are consistent with a model whereby proteolytic intermediates of C with an intact transmembrane ER-anchor assemble into pore-like structures in the ER membrane.
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Affiliation(s)
- Priya Devi
- Department of Medical Sciences, Uppsala University, SE 75185 Uppsala, Sweden;
| | - Tanel Punga
- Department of Medical Biochemistry and Microbiology, Uppsala University, SE 75123 Uppsala, Sweden;
| | - Anders Bergqvist
- Department of Medical Sciences, Uppsala University, SE 75185 Uppsala, Sweden;
- Clinical Microbiology and Hospital Infection Control, Uppsala University Hospital, SE 75185 Uppsala, Sweden
- Correspondence: ; Tel.: +46-186113937
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8
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Ajjaji D, Ben M'barek K, Boson B, Omrane M, Gassama-Diagne A, Blaud M, Penin F, Diaz E, Ducos B, Cosset FL, Thiam AR. Hepatitis C virus core protein uses triacylglycerols to fold onto the endoplasmic reticulum membrane. Traffic 2021; 23:63-80. [PMID: 34729868 DOI: 10.1111/tra.12825] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Revised: 10/16/2021] [Accepted: 11/01/2021] [Indexed: 12/12/2022]
Abstract
Lipid droplets (LDs) are involved in viral infections, but exactly how remains unclear. Here, we study the hepatitis C virus (HCV) whose core capsid protein binds to LDs but is also involved in the assembly of virions at the endoplasmic reticulum (ER) bilayer. We found that the amphipathic helix-containing domain of core, D2, senses triglycerides (TGs) rather than LDs per se. In the absence of LDs, D2 can bind to the ER membrane but only if TG molecules are present in the bilayer. Accordingly, the pharmacological inhibition of the diacylglycerol O-acyltransferase enzymes, mediating TG synthesis in the ER, inhibits D2 association with the bilayer. We found that TG molecules enable D2 to fold into alpha helices. Sequence analysis reveals that D2 resembles the apoE lipid-binding region. Our data support that TG in LDs promotes the folding of core, which subsequently relocalizes to contiguous ER regions. During this motion, core may carry TG molecules to these regions where HCV lipoviroparticles likely assemble. Consistent with this model, the inhibition of Arf1/COPI, which decreases LD surface accessibility to proteins and ER-LD material exchange, severely impedes the assembly of virions. Altogether, our data uncover a critical function of TG in the folding of core and HCV replication and reveals, more broadly, how TG accumulation in the ER may provoke the binding of soluble amphipathic helix-containing proteins to the ER bilayer.
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Affiliation(s)
- Dalila Ajjaji
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, 24 rue Lhomond, Paris, 75005, France
| | - Kalthoum Ben M'barek
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, 24 rue Lhomond, Paris, 75005, France
| | - Bertrand Boson
- CIRI-Centre International de Recherche en Infectiologie, Univ Lyon, Université Claude Bernard Lyon 1, Inserm, U1111, CNRS, UMR5308, ENS Lyon, Lyon, France
| | - Mohyeddine Omrane
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, 24 rue Lhomond, Paris, 75005, France
| | - Ama Gassama-Diagne
- INSERM, Unité 1193, Villejuif, France.,Université Paris-Sud, UMR-S 1193, Villejuif, France
| | - Magali Blaud
- Université de Paris, CiTCoM, CNRS, Paris, France
| | - François Penin
- Institut de Biologie et Chimie des Protéines, Bases Moléculaires et Structurales des Systèmes Infectieux, UMR 5086, CNRS, Labex Ecofect, University of Lyon, Lyon, France
| | - Elise Diaz
- High Throughput qPCR Core Facility of the ENS, IBENS, PSL Research University, Paris, France
| | - Bertrand Ducos
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, 24 rue Lhomond, Paris, 75005, France.,High Throughput qPCR Core Facility of the ENS, IBENS, PSL Research University, Paris, France
| | - François-Loïc Cosset
- CIRI-Centre International de Recherche en Infectiologie, Univ Lyon, Université Claude Bernard Lyon 1, Inserm, U1111, CNRS, UMR5308, ENS Lyon, Lyon, France
| | - Abdou Rachid Thiam
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, 24 rue Lhomond, Paris, 75005, France
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9
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Wang B, Zhu Y, Yu C, Zhang C, Tang Q, Huang H, Zhao Z. Hepatitis C virus induces oxidation and degradation of apolipoprotein B to enhance lipid accumulation and promote viral production. PLoS Pathog 2021; 17:e1009889. [PMID: 34492079 PMCID: PMC8448335 DOI: 10.1371/journal.ppat.1009889] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 09/17/2021] [Accepted: 08/14/2021] [Indexed: 12/14/2022] Open
Abstract
Hepatitis C virus (HCV) infection induces the degradation and decreases the secretion of apolipoprotein B (ApoB). Impaired production and secretion of ApoB-containing lipoprotein is associated with an increase in hepatic steatosis. Therefore, HCV infection-induced degradation of ApoB may contribute to hepatic steatosis and decreased lipoprotein secretion, but the mechanism of HCV infection-induced ApoB degradation has not been completely elucidated. In this study, we found that the ApoB level in HCV-infected cells was regulated by proteasome-associated degradation but not autophagic degradation. ApoB was degraded by the 20S proteasome in a ubiquitin-independent manner. HCV induced the oxidation of ApoB via oxidative stress, and oxidized ApoB was recognized by the PSMA5 and PSMA6 subunits of the 20S proteasome for degradation. Further study showed that ApoB was degraded at endoplasmic reticulum (ER)-associated lipid droplets (LDs) and that the retrotranslocation and degradation of ApoB required Derlin-1 but not gp78 or p97. Moreover, we found that knockdown of ApoB before infection increased the cellular lipid content and enhanced HCV assembly. Overexpression of ApoB-50 inhibited lipid accumulation and repressed viral assembly in HCV-infected cells. Our study reveals a novel mechanism of ApoB degradation and lipid accumulation during HCV infection and might suggest new therapeutic strategies for hepatic steatosis. Hepatitis C virus (HCV) infection induces the degradation of apolipoprotein B (ApoB), which is the primary apolipoprotein in low-density lipoprotein (LDL) and very low-density lipoprotein (VLDL). Impaired production and secretion of ApoB-containing lipoprotein is associated with an increase in hepatic steatosis. Thus, ApoB degradation might contribute to HCV infection-induced fatty liver. Here, we found that ApoB was not degraded through endoplasmic reticulum-associated degradation (ERAD) or autophagy, as reported previously. Instead, HCV infection induced ApoB oxidation through oxidative stress, and oxidatively damaged ApoB could be recognized and directly degraded by the 20S proteasome. We also found that ApoB was retrotranslocated from the endoplasmic reticulum (ER) to lipid droplets (LDs) for degradation. Through overexpression of ApoB-50, which can mediate the assembly and secretion of LDL and VLDL, we confirmed that ApoB degradation contributed to hepatocellular lipid accumulation induced by HCV infection. Additionally, expression of ApoB-50 impaired HCV production due to the observed decrease in lipid accumulation. In this study, we identified new mechanisms of ApoB degradation and HCV-induced lipid accumulation, and our findings might facilitate the development of novel therapeutic strategies for HCV infection-induced fatty liver.
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Affiliation(s)
- Bei Wang
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
- Clinical Immunology Center, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Yue Zhu
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Congci Yu
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Chongyang Zhang
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Qing Tang
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - He Huang
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
- Clinical Immunology Center, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
- * E-mail:
| | - Zhendong Zhao
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
- Clinical Immunology Center, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
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10
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Galli A, Ramirez S, Bukh J. Lipid Droplets Accumulation during Hepatitis C Virus Infection in Cell-Culture Varies among Genotype 1-3 Strains and Does Not Correlate with Virus Replication. Viruses 2021; 13:389. [PMID: 33671086 PMCID: PMC7999684 DOI: 10.3390/v13030389] [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: 01/08/2021] [Revised: 02/22/2021] [Accepted: 02/24/2021] [Indexed: 12/26/2022] Open
Abstract
Liver steatosis is a common complication of chronic hepatitis C virus (HCV) infection, which can result in accelerated liver fibrosis development, especially in patients infected with genotype 3a. The precise mechanisms of HCV-induced liver steatosis remain unclear, but it is often posited that increased intracellular lipid accumulation is the underlying cause of steatosis. To study experimentally how HCV infection in human liver derived cells by different genotypes and subtypes might affect lipid accumulation, we performed detailed cytofluorimetric and microscopy analyses of intracellular lipid droplets (LDs) in relation to the viral Core and to cell endoplasmic reticulum proteins. Following culture infection with HCV genotype 1a, 2a, 2b, 2c, and 3a strains, we found variable levels of intracellular LDs accumulation, associated to the infecting strain rather than to the specific genotype. Although two genotype 3a strains showed high levels of lipid accumulation, as previously observed, some strains of other genotypes displayed a similar phenotype. Moreover, the analyses of LDs size, number, and shape indicated that the apparent increase in lipid accumulation is due to an increase in the overall number rather than in the size of droplets. Finally, differences in total lipid content across genotypes did not correlate to differences in Core distribution nor Core levels. In conclusion, our study provides a quantitative in-depth analysis of the effect of HCV infection on LDs accumulation in cell-culture.
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Affiliation(s)
- Andrea Galli
- Copenhagen Hepatitis C Program (CO-HEP), Department of Infectious Diseases, Hvidovre Hospital, 2650 Hvidovre, Denmark; (A.G.); (S.R.)
- Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Santseharay Ramirez
- Copenhagen Hepatitis C Program (CO-HEP), Department of Infectious Diseases, Hvidovre Hospital, 2650 Hvidovre, Denmark; (A.G.); (S.R.)
- Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Jens Bukh
- Copenhagen Hepatitis C Program (CO-HEP), Department of Infectious Diseases, Hvidovre Hospital, 2650 Hvidovre, Denmark; (A.G.); (S.R.)
- Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
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11
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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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12
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Abstract
Persistent infection with hepatitis C virus (HCV) is a major risk factor for hepatocellular carcinoma (HCC). Accumulating evidence suggests that not only inflammation and subsequent fibrosis but also HCV itself are associated with hepatocarcinogenesis. To date, studies using transgenic mouse and cell-culture models, in which HCV proteins are expressed, indicate the direct pathogenicity of HCV, including oncogenic activity. In particular, the core protein of HCV induces excessive oxidative stress by impairing the mitochondrial electron transfer system by disrupting the function of the molecular chaperone, prohibitin. HCV also modulates intracellular signaling pathways, including mitogen-activated protein kinase, promoting the proliferation of hepatocytes. In addition, HCV induces disorders in lipid and glucose metabolism, thereby accelerating the progression of liver fibrosis and the development of HCC. Due to the development of direct-acting antivirals, which was made possible by basic research, HCV can be eradicated from almost all infected patients. However, such patients can develop HCC long after eradication of HCV, suggesting the genetic and/or epigenetic changes induced by HCV may be persistent. These results enhance our understanding of the role of HCV in hepatocarcinogenesis and will facilitate the development of therapeutic and preventive strategies for HCV-induced HCC.
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13
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Lee JY, Cortese M, Haselmann U, Tabata K, Romero-Brey I, Funaya C, Schieber NL, Qiang Y, Bartenschlager M, Kallis S, Ritter C, Rohr K, Schwab Y, Ruggieri A, Bartenschlager R. Spatiotemporal Coupling of the Hepatitis C Virus Replication Cycle by Creating a Lipid Droplet- Proximal Membranous Replication Compartment. Cell Rep 2020; 27:3602-3617.e5. [PMID: 31216478 DOI: 10.1016/j.celrep.2019.05.063] [Citation(s) in RCA: 74] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Revised: 04/05/2019] [Accepted: 05/17/2019] [Indexed: 02/08/2023] Open
Abstract
The hepatitis C virus (HCV) is a major cause of chronic liver disease, affecting around 71 million people worldwide. Viral RNA replication occurs in a membranous compartment composed of double-membrane vesicles (DMVs), whereas virus particles are thought to form by budding into the endoplasmic reticulum (ER). It is unknown how these steps are orchestrated in space and time. Here, we established an imaging system to visualize HCV structural and replicase proteins in live cells and with high resolution. We determined the conditions for the recruitment of viral proteins to putative assembly sites and studied the dynamics of this event and the underlying ultrastructure. Most notable was the selective recruitment of ER membranes around lipid droplets where structural proteins and the viral replicase colocalize. Moreover, ER membranes wrapping lipid droplets were decorated with double membrane vesicles, providing a topological map of how HCV might coordinate the steps of viral replication and virion assembly.
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Affiliation(s)
- Ji-Young Lee
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Im Neuenheimer Feld 344, 69120 Heidelberg, Germany; German Center for Infection Research, Heidelberg Partner Site, Im Neuenheimer Feld 344, 69120 Heidelberg, Germany
| | - Mirko Cortese
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Im Neuenheimer Feld 344, 69120 Heidelberg, Germany
| | - Uta Haselmann
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Im Neuenheimer Feld 344, 69120 Heidelberg, Germany
| | - Keisuke Tabata
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Im Neuenheimer Feld 344, 69120 Heidelberg, Germany
| | - Inés Romero-Brey
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Im Neuenheimer Feld 344, 69120 Heidelberg, Germany
| | - Charlotta Funaya
- Electron Microscopy Core Facility, Heidelberg University, 69120 Heidelberg, Germany
| | - Nicole L Schieber
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Yu Qiang
- Biomedical Computer Vision Group, Heidelberg University, BIOQUANT, IPMB, and DKFZ Heidelberg, Im Neuenheimer Feld 267, 69120 Heidelberg, Germany
| | - Marie Bartenschlager
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Im Neuenheimer Feld 344, 69120 Heidelberg, Germany
| | - Stephanie Kallis
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Im Neuenheimer Feld 344, 69120 Heidelberg, Germany
| | - Christian Ritter
- Biomedical Computer Vision Group, Heidelberg University, BIOQUANT, IPMB, and DKFZ Heidelberg, Im Neuenheimer Feld 267, 69120 Heidelberg, Germany
| | - Karl Rohr
- Biomedical Computer Vision Group, Heidelberg University, BIOQUANT, IPMB, and DKFZ Heidelberg, Im Neuenheimer Feld 267, 69120 Heidelberg, Germany
| | - Yannick Schwab
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany; Electron Microscopy Core Facility, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Alessia Ruggieri
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Im Neuenheimer Feld 344, 69120 Heidelberg, Germany
| | - Ralf Bartenschlager
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Im Neuenheimer Feld 344, 69120 Heidelberg, Germany; German Center for Infection Research, Heidelberg Partner Site, Im Neuenheimer Feld 344, 69120 Heidelberg, Germany; Division of Virus-Associated Carcinogenesis, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 242, Heidelberg, Germany.
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14
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Hammoudeh N, Soukkarieh C, Murphy DJ, Hanano A. Involvement of hepatic lipid droplets and their associated proteins in the detoxification of aflatoxin B 1 in aflatoxin-resistance BALB/C mouse. Toxicol Rep 2020; 7:795-804. [PMID: 32642446 PMCID: PMC7334552 DOI: 10.1016/j.toxrep.2020.06.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 06/04/2020] [Accepted: 06/11/2020] [Indexed: 12/14/2022] Open
Abstract
The highly potent carcinogen, Aflatoxin B1, induces liver cancer in many animals including humans but some mice strains are highly resistant. This murine resistance is due to a rapid detoxification of AFB1. Hepatic lipid droplets (LDs) ultimately impact the liver functions but their potential role in AFB1 detoxification has not been addressed. This study describes the structural and functional impacts on hepatic LDs in BALB/C mice after exposure to 44 (low dose) or 663 (high dose) μg AFB1/kg of body weight. After 7 days, the liver of AFB1-dosed mice did not accumulate any detectable AFB1 or its metabolites and this was associated with a net increase in gene transcripts of the AhR-mediating pathway. Of particular interest, the livers of high-dose mice accumulated many more LDs than those of low-dose mice. This was accompanied with a net increase in transcript levels of LD-associated protein-encoding genes including Plin2, Plin3 and Cideb and an alteration in the LDs lipid profiles that could be likely due to the induction of lipoxygenase and cyclooxygenase genes. Interestingly, our data suggest that hepatic LDs catalyze the in vitro activation of AFB1 into AFB1-exo-8,9-epoxide and subsequent hydrolysis of this epoxide into its corresponding dihydrodiol. Finally, transcript levels of CYP1A2, CYP1B1, GSTA3 and EH1 genes were elevated in livers of high-dose mice. These data suggest new roles for hepatic LDs in the trapping and detoxifying of aflatoxins.
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Affiliation(s)
- Nour Hammoudeh
- Department of Animal Biology, Damascus University, Damascus, Syria
| | - Chadi Soukkarieh
- Department of Animal Biology, Damascus University, Damascus, Syria
| | - Denis J Murphy
- Genomics and Computational Biology Group, University of South Wales, Wales, United Kingdom
| | - Abdulsamie Hanano
- Department of Molecular Biology and Biotechnology, Atomic Energy Commission of Syria (AECS), P.O. Box 6091, Damascus, Syria
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15
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Bender D, Hildt E. Effect of Hepatitis Viruses on the Nrf2/Keap1-Signaling Pathway and Its Impact on Viral Replication and Pathogenesis. Int J Mol Sci 2019; 20:ijms20184659. [PMID: 31546975 PMCID: PMC6769940 DOI: 10.3390/ijms20184659] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 09/16/2019] [Accepted: 09/17/2019] [Indexed: 12/15/2022] Open
Abstract
With respect to their genome and their structure, the human hepatitis B virus (HBV) and hepatitis C virus (HCV) are complete different viruses. However, both viruses can cause an acute and chronic infection of the liver that is associated with liver inflammation (hepatitis). For both viruses chronic infection can lead to fibrosis, cirrhosis and hepatocellular carcinoma (HCC). Reactive oxygen species (ROS) play a central role in a variety of chronic inflammatory diseases. In light of this, this review summarizes the impact of both viruses on ROS-generating and ROS-inactivating mechanisms. The focus is on the effect of both viruses on the transcription factor Nrf2 (nuclear factor erythroid 2 (NF-E2)-related factor 2). By binding to its target sequence, the antioxidant response element (ARE), Nrf2 triggers the expression of a variety of cytoprotective genes including ROS-detoxifying enzymes. The review summarizes the literature about the pathways for the modulation of Nrf2 that are deregulated by HBV and HCV and describes the impact of Nrf2 deregulation on the viral life cycle of the respective viruses and the virus-associated pathogenesis.
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Affiliation(s)
- Daniela Bender
- Department of Virology, Paul-Ehrlich-Institut, Paul-Ehrlich-Straβe 51-59, D-63225 Langen, Germany.
| | - Eberhard Hildt
- Department of Virology, Paul-Ehrlich-Institut, Paul-Ehrlich-Straβe 51-59, D-63225 Langen, Germany.
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16
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Pereira-Dutra FS, Teixeira L, de Souza Costa MF, Bozza PT. Fat, fight, and beyond: The multiple roles of lipid droplets in infections and inflammation. J Leukoc Biol 2019; 106:563-580. [PMID: 31121077 DOI: 10.1002/jlb.4mr0119-035r] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2019] [Revised: 04/16/2019] [Accepted: 04/26/2019] [Indexed: 12/12/2022] Open
Abstract
Increased accumulation of cytoplasmic lipid droplets (LDs) in host nonadipose cells is commonly observed in response to numerous infectious diseases, including bacterial, parasite, and fungal infections. LDs are lipid-enriched, dynamic organelles composed of a core of neutral lipids surrounded by a monolayer of phospholipids associated with a diverse array of proteins that are cell and stimulus regulated. Far beyond being simply a deposit of neutral lipids, LDs have come to be seen as an essential platform for various cellular processes, including metabolic regulation, cell signaling, and the immune response. LD participation in the immune response occurs as sites for compartmentalization of several immunometabolic signaling pathways, production of inflammatory lipid mediators, and regulation of antigen presentation. Infection-driven LD biogenesis is a complexly regulated process that involves innate immune receptors, transcriptional and posttranscriptional regulation, increased lipid uptake, and new lipid synthesis. Accumulating evidence demonstrates that intracellular pathogens are able to exploit LDs as an energy source, a replication site, and/or a mechanism of immune response evasion. Nevertheless, LDs can also act in favor of the host as part of the immune and inflammatory response to pathogens. Here, we review recent findings that explored the new roles of LDs in the context of host-pathogen interactions.
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Affiliation(s)
- Filipe S Pereira-Dutra
- Laboratório de Imunofarmacologia, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Livia Teixeira
- Laboratório de Imunofarmacologia, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | | | - Patrícia T Bozza
- Laboratório de Imunofarmacologia, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
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17
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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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18
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Zhang C, Liu P. The New Face of the Lipid Droplet: Lipid Droplet Proteins. Proteomics 2018; 19:e1700223. [DOI: 10.1002/pmic.201700223] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2018] [Revised: 08/13/2018] [Indexed: 12/20/2022]
Affiliation(s)
- Congyan Zhang
- National Laboratory of BiomacromoleculesCAS Center for Excellence in BiomacromoleculesInstitute of BiophysicsChinese Academy of Sciences Beijing 100101 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Pingsheng Liu
- National Laboratory of BiomacromoleculesCAS Center for Excellence in BiomacromoleculesInstitute of BiophysicsChinese Academy of Sciences Beijing 100101 China
- University of Chinese Academy of Sciences Beijing 100049 China
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19
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Martins AS, Martins IC, Santos NC. Methods for Lipid Droplet Biophysical Characterization in Flaviviridae Infections. Front Microbiol 2018; 9:1951. [PMID: 30186265 PMCID: PMC6110928 DOI: 10.3389/fmicb.2018.01951] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Accepted: 08/02/2018] [Indexed: 01/14/2023] Open
Abstract
Lipid droplets (LDs) are intracellular organelles for neutral lipid storage, originated from the endoplasmic reticulum. They play an essential role in lipid metabolism and cellular homeostasis. In fact, LDs are complex organelles, involved in many more cellular processes than those initially proposed. They have been extensively studied in the context of LD-associated pathologies. In particular, LDs have emerged as critical for virus replication and assembly. Viruses from the Flaviviridae family, namely dengue virus (DENV), hepatitis C virus (HCV), West Nile virus (WNV), and Zika virus (ZIKV), interact with LDs to usurp the host lipid metabolism for their own viral replication and pathogenesis. In general, during Flaviviridae infections it is observed an increasing number of host intracellular LDs. Several viral proteins interact with LDs during different steps of the viral life cycle. The HCV core protein and DENV capsid protein, extensively interact with LDs to regulate their replication and assembly. Detailed studies of LDs in viral infections may contribute for the development of possible inhibitors of key steps of viral replication. Here, we reviewed different techniques that can be used to characterize LDs isolated from infected or non-infected cells. Microscopy studies have been commonly used to observe LDs accumulation and localization in infected cell cultures. Fluorescent dyes, which may affect LDs directly, are widely used to probe LDs but there are also approaches that do not require the use of fluorescence, namely stimulated Raman scattering, electron and atomic force microscopy-based approaches. These three are powerful techniques to characterize LDs morphology. Raman scattering microscopy allows studying LDs in a single cell. Electron and atomic force microscopies enable a better characterization of LDs in terms of structure and interaction with other organelles. Other biophysical techniques, such as dynamic light scattering and zeta potential are also excellent to characterize LDs in terms of size in a simple and fast way and test possible LDs interaction with viral proteins. These methodologies are reviewed in detail, in the context of viral studies.
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Affiliation(s)
- Ana S Martins
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Ivo C Martins
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Nuno C Santos
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
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20
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Vallochi AL, Teixeira L, Oliveira KDS, Maya-Monteiro CM, Bozza PT. Lipid Droplet, a Key Player in Host-Parasite Interactions. Front Immunol 2018; 9:1022. [PMID: 29875768 PMCID: PMC5974170 DOI: 10.3389/fimmu.2018.01022] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 04/24/2018] [Indexed: 12/18/2022] Open
Abstract
Lipid droplets (lipid bodies, LDs) are dynamic organelles that have important roles in regulating lipid metabolism, energy homeostasis, cell signaling, membrane trafficking, and inflammation. LD biogenesis, composition, and functions are highly regulated and may vary according to the stimuli, cell type, activation state, and inflammatory environment. Increased cytoplasmic LDs are frequently observed in leukocytes and other cells in a number of infectious diseases. Accumulating evidence reveals LDs participation in fundamental mechanisms of host-pathogen interactions, including cell signaling and immunity. LDs are sources of eicosanoid production, and may participate in different aspects of innate signaling and antigen presentation. In addition, intracellular pathogens evolved mechanisms to subvert host metabolism and may use host LDs, as ways of immune evasion and nutrients source. Here, we review mechanisms of LDs biogenesis and their contributions to the infection progress, and discuss the latest discoveries on mechanisms and pathways involving LDs roles as regulators of the immune response to protozoan infection.
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Affiliation(s)
- Adriana Lima Vallochi
- Laboratório de Imunofarmacologia, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz (FIOCRUZ), Rio de Janeiro, Brazil
| | | | | | | | - Patricia T. Bozza
- Laboratório de Imunofarmacologia, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz (FIOCRUZ), Rio de Janeiro, Brazil
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21
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Shimizu K, Soroida Y, Sato M, Hikita H, Kobayashi T, Endo M, Sato M, Gotoh H, Iwai T, Tateishi R, Koike K, Yatomi Y, Ikeda H. Eradication of hepatitis C virus is associated with the attenuation of steatosis as evaluated using a controlled attenuation parameter. Sci Rep 2018; 8:7845. [PMID: 29777191 PMCID: PMC5959884 DOI: 10.1038/s41598-018-26293-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Accepted: 05/02/2018] [Indexed: 01/07/2023] Open
Abstract
Chronic hepatitis C virus (HCV) infection was shown to cause hepatic steatosis or suppression of serum lipid levels. However, little is known about the changes in hepatic steatosis following HCV eradication. We aimed to evaluate this issue using the controlled attenuation parameter (CAP), which was recently shown to provide a standardized non-invasive measure of hepatic steatosis. We enrolled 70 patients with chronic HCV infections and steatosis (CAP of over 248 dB/m) who had achieved a sustained viral response at 12 weeks after discontinuation of antiviral treatment using direct-acting antivirals (DAA). We then evaluated the state of hepatic steatosis before and after HCV eradication. We also investigated the changes in serum parameters such as cholesterol and glucose levels. The median value of CAP level decreased significantly after HCV eradication from 273 dB/m to 265 dB/m (P = 0.034). Also, LDL and HDL cholesterol levels increased significantly after HCV eradication (P = 0.002 and P = 0.027, respectively). In conclusion, a decrease in hepatic steatosis after HCV eradication with DAA was revealed in chronic hepatitis C patients with significant steatosis. Cancellation of the viral effect is a possible underlying cause of hepatic steatosis improvement and increase in HDL and LDL cholesterol levels.
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Affiliation(s)
- Kohei Shimizu
- Department of Clinical Laboratory Medicine, The University of Tokyo, Tokyo, Japan
| | - Yoko Soroida
- Department of Clinical Laboratory Medicine, The University of Tokyo, Tokyo, Japan
| | - Masaya Sato
- Department of Clinical Laboratory Medicine, The University of Tokyo, Tokyo, Japan. .,Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
| | - Hiromi Hikita
- Department of Clinical Laboratory Medicine, The University of Tokyo, Tokyo, Japan
| | - Tamaki Kobayashi
- Department of Clinical Laboratory Medicine, The University of Tokyo, Tokyo, Japan
| | - Momoe Endo
- Department of Clinical Laboratory Medicine, The University of Tokyo, Tokyo, Japan
| | - Mamiko Sato
- Department of Clinical Laboratory Medicine, The University of Tokyo, Tokyo, Japan
| | - Hiroaki Gotoh
- Department of Clinical Laboratory Medicine, The University of Tokyo, Tokyo, Japan
| | - Tomomi Iwai
- Department of Clinical Laboratory Medicine, The University of Tokyo, Tokyo, Japan
| | - Ryosuke Tateishi
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Kazuhiko Koike
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Yutaka Yatomi
- Department of Clinical Laboratory Medicine, The University of Tokyo, Tokyo, Japan
| | - Hitoshi Ikeda
- Department of Clinical Laboratory Medicine, The University of Tokyo, Tokyo, Japan.,Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
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22
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den Brok MH, Raaijmakers TK, Collado-Camps E, Adema GJ. Lipid Droplets as Immune Modulators in Myeloid Cells. Trends Immunol 2018; 39:380-392. [DOI: 10.1016/j.it.2018.01.012] [Citation(s) in RCA: 105] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 12/14/2017] [Accepted: 01/23/2018] [Indexed: 12/23/2022]
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23
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Oxidative stress, a trigger of hepatitis C and B virus-induced liver carcinogenesis. Oncotarget 2018; 8:3895-3932. [PMID: 27965466 PMCID: PMC5354803 DOI: 10.18632/oncotarget.13904] [Citation(s) in RCA: 116] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 12/05/2016] [Indexed: 12/11/2022] Open
Abstract
Virally induced liver cancer usually evolves over long periods of time in the context of a strongly oxidative microenvironment, characterized by chronic liver inflammation and regeneration processes. They ultimately lead to oncogenic mutations in many cellular signaling cascades that drive cell growth and proliferation. Oxidative stress, induced by hepatitis viruses, therefore is one of the factors that drives the neoplastic transformation process in the liver. This review summarizes current knowledge on oxidative stress and oxidative stress responses induced by human hepatitis B and C viruses. It focuses on the molecular mechanisms by which these viruses activate cellular enzymes/systems that generate or scavenge reactive oxygen species (ROS) and control cellular redox homeostasis. The impact of an altered cellular redox homeostasis on the initiation and establishment of chronic viral infection, as well as on the course and outcome of liver fibrosis and hepatocarcinogenesis will be discussed The review neither discusses reactive nitrogen species, although their metabolism is interferes with that of ROS, nor antioxidants as potential therapeutic remedies against viral infections, both subjects meriting an independent review.
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24
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Jardim ACG, Shimizu JF, Rahal P, Harris M. Plant-derived antivirals against hepatitis c virus infection. Virol J 2018; 15:34. [PMID: 29439720 PMCID: PMC5812025 DOI: 10.1186/s12985-018-0945-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Accepted: 02/02/2018] [Indexed: 12/15/2022] Open
Abstract
Hepatitis C virus (HCV) infection is a worldwide public health burden and it is estimated that 185 million people are or have previously been infected worldwide. There is no effective vaccine for prevention of HCV infection; however, a number of drugs are available for the treatment of infection. The availability of direct-acting antivirals (DAAs) has dramatically improved therapeutic options for HCV genotype 1. However, the high costs and potential for development of resistance presented by existing treatment demonstrate the need for the development of more efficient new antivirals, or combination of therapies that target different stages of the viral lifecycle. Over the past decades, there has been substantial study of compounds extracted from plants that have activity against a range of microorganisms that cause human diseases. An extensive variety of natural compounds has demonstrated antiviral action worldwide, including anti-HCV activity. In this context, plant-derived compounds can provide an alternative approach to new antivirals. In this review, we aim to summarize the most promising plant-derived compounds described to have antiviral activity against HCV.
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Affiliation(s)
- Ana Carolina Gomes Jardim
- Laboratory of Virology, Institute of Biomedical Science, ICBIM, Federal University of Uberlândia, Avenida Amazonas, Bloco 4C – sala 216. Umuarama, Uberlândia, MG CEP: 38405-302 Brazil
- Genomics Study Laboratory, São Paulo State University, São José do Rio Preto, SP Brazil
| | - Jacqueline Farinha Shimizu
- Laboratory of Virology, Institute of Biomedical Science, ICBIM, Federal University of Uberlândia, Avenida Amazonas, Bloco 4C – sala 216. Umuarama, Uberlândia, MG CEP: 38405-302 Brazil
- Genomics Study Laboratory, São Paulo State University, São José do Rio Preto, SP Brazil
| | - Paula Rahal
- Genomics Study Laboratory, São Paulo State University, São José do Rio Preto, SP Brazil
| | - Mark Harris
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT UK
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Prévost C, Sharp ME, Kory N, Lin Q, Voth GA, Farese RV, Walther TC. Mechanism and Determinants of Amphipathic Helix-Containing Protein Targeting to Lipid Droplets. Dev Cell 2018; 44:73-86.e4. [PMID: 29316443 DOI: 10.1016/j.devcel.2017.12.011] [Citation(s) in RCA: 146] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 11/02/2017] [Accepted: 12/07/2017] [Indexed: 11/30/2022]
Abstract
Cytosolic lipid droplets (LDs) are the main storage organelles for metabolic energy in most cells. They are unusual organelles that are bounded by a phospholipid monolayer and specific surface proteins, including key enzymes of lipid and energy metabolism. Proteins targeting LDs from the cytoplasm often contain amphipathic helices, but how they bind to LDs is not well understood. Combining computer simulations with experimental studies in vitro and in cells, we uncover a general mechanism for targeting of cytosolic proteins to LDs: large hydrophobic residues of amphipathic helices detect and bind to large, persistent membrane packing defects that are unique to the LD surface. Surprisingly, amphipathic helices with large hydrophobic residues from many different proteins are capable of binding to LDs. This suggests that LD protein composition is additionally determined by mechanisms that selectively prevent proteins from binding LDs, such as macromolecular crowding at the LD surface.
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Affiliation(s)
- Coline Prévost
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA; Broad Institute of Harvard and MIT, Cambridge, MA 02124, USA
| | - Morris E Sharp
- Department of Chemistry, James Franck Institute, and Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL 60637, USA
| | - Nora Kory
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA; Broad Institute of Harvard and MIT, Cambridge, MA 02124, USA
| | - Qingqing Lin
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA; Broad Institute of Harvard and MIT, Cambridge, MA 02124, USA
| | - Gregory A Voth
- Department of Chemistry, James Franck Institute, and Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL 60637, USA.
| | - Robert V Farese
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA; Broad Institute of Harvard and MIT, Cambridge, MA 02124, USA.
| | - Tobias C Walther
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA; Broad Institute of Harvard and MIT, Cambridge, MA 02124, USA; Howard Hughes Medical Institute, Boston, MA 02115, USA.
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26
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Fernández-Ponce C, Durán-Ruiz MC, Narbona-Sánchez I, Muñoz-Miranda JP, Arbulo-Echevarria MM, Serna-Sanz A, Baumann C, Litrán R, Aguado E, Bloch W, García-Cozar F. Ultrastructural Localization and Molecular Associations of HCV Capsid Protein in Jurkat T Cells. Front Microbiol 2018; 8:2595. [PMID: 29354102 PMCID: PMC5758585 DOI: 10.3389/fmicb.2017.02595] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Accepted: 12/12/2017] [Indexed: 12/24/2022] Open
Abstract
Hepatitis C virus core protein is a highly basic viral protein that multimerizes with itself to form the viral capsid. When expressed in CD4+ T lymphocytes, it can induce modifications in several essential cellular and biological networks. To shed light on the mechanisms underlying the alterations caused by the viral protein, we have analyzed HCV-core subcellular localization and its associations with host proteins in Jurkat T cells. In order to investigate the intracellular localization of Hepatitis C virus core protein, we have used a lentiviral system to transduce Jurkat T cells and subsequently localize the protein using immunoelectron microscopy techniques. We found that in Jurkat T cells, Hepatitis C virus core protein mostly localizes in the nucleus and specifically in the nucleolus. In addition, we performed pull-down assays combined with Mass Spectrometry Analysis, to identify proteins that associate with Hepatitis C virus core in Jurkat T cells. We found proteins such as NOLC1, PP1γ, ILF3, and C1QBP implicated in localization and/or traffic to the nucleolus. HCV-core associated proteins are implicated in RNA processing and RNA virus infection as well as in functions previously shown to be altered in Hepatitis C virus core expressing CD4+ T cells, such as cell cycle delay, decreased proliferation, and induction of a regulatory phenotype. Thus, in the current work, we show the ultrastructural localization of Hepatitis C virus core and the first profile of HCV core associated proteins in T cells, and we discuss the functions and interconnections of these proteins in molecular networks where relevant biological modifications have been described upon the expression of Hepatitis C virus core protein. Thereby, the current work constitutes a necessary step toward understanding the mechanisms underlying HCV core mediated alterations that had been described in relevant biological processes in CD4+ T cells.
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Affiliation(s)
- Cecilia Fernández-Ponce
- Department of Biomedicine, Biotechnology and Public Health, University of Cadiz and Institute of Biomedical Research Cádiz (INIBICA), Cadiz, Spain
| | - Maria C Durán-Ruiz
- Department of Biomedicine, Biotechnology and Public Health, University of Cadiz and Institute of Biomedical Research Cádiz (INIBICA), Cadiz, Spain
| | - Isaac Narbona-Sánchez
- Department of Biomedicine, Biotechnology and Public Health, University of Cadiz and Institute of Biomedical Research Cádiz (INIBICA), Cadiz, Spain
| | - Juan P Muñoz-Miranda
- Department of Biomedicine, Biotechnology and Public Health, University of Cadiz and Institute of Biomedical Research Cádiz (INIBICA), Cadiz, Spain
| | - Mikel M Arbulo-Echevarria
- Department of Biomedicine, Biotechnology and Public Health, University of Cadiz and Institute of Biomedical Research Cádiz (INIBICA), Cadiz, Spain
| | | | | | - Rocío Litrán
- Department of Condensed Matter Physics, University of Cádiz, Puerto Real, Spain
| | - Enrique Aguado
- Department of Biomedicine, Biotechnology and Public Health, University of Cadiz and Institute of Biomedical Research Cádiz (INIBICA), Cadiz, Spain
| | - Wilhelm Bloch
- Department of Molecular and Cellular Sport Medicine, Institute of Cardiovascular Research and Sport Medicine, German Sport University Cologne, Cologne, Germany
| | - Francisco García-Cozar
- Department of Biomedicine, Biotechnology and Public Health, University of Cadiz and Institute of Biomedical Research Cádiz (INIBICA), Cadiz, Spain
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27
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Holmstrom ED, Nettels D, Schuler B. Conformational Plasticity of Hepatitis C Virus Core Protein Enables RNA-Induced Formation of Nucleocapsid-like Particles. J Mol Biol 2017; 430:2453-2467. [PMID: 29045818 DOI: 10.1016/j.jmb.2017.10.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 09/29/2017] [Accepted: 10/02/2017] [Indexed: 02/08/2023]
Abstract
Many of the unanswered questions associated with hepatitis C virus assembly are related to the core protein (HCVcp), which forms an oligomeric nucleocapsid encompassing the viral genome. The structural properties of HCVcp have been difficult to quantify, at least in part because it is an intrinsically disordered protein. We have used single-molecule Förster Resonance Energy Transfer techniques to study the conformational dimensions and dynamics of the HCVcp nucleocapsid domain (HCVncd) at various stages during the RNA-induced formation of nucleocapsid-like particles. Our results indicate that HCVncd is a typical intrinsically disordered protein. When it forms small ribonucleoprotein complexes with various RNA hairpins from the 3' end of the HCV genome, it compacts but remains intrinsically disordered and conformationally dynamic. Above a critical RNA concentration, these ribonucleoprotein complexes rapidly and cooperatively assemble into large nucleocapsid-like particles, wherein the individual HCVncd subunits become substantially more extended.
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Affiliation(s)
- Erik D Holmstrom
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
| | - Daniel Nettels
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
| | - Benjamin Schuler
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland; Department of Physics, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
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28
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Barriocanal M, Fortes P. Long Non-coding RNAs in Hepatitis C Virus-Infected Cells. Front Microbiol 2017; 8:1833. [PMID: 29033906 PMCID: PMC5625025 DOI: 10.3389/fmicb.2017.01833] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 09/06/2017] [Indexed: 12/13/2022] Open
Abstract
Hepatitis C virus (HCV) often leads to a chronic infection in the liver that may progress to steatosis, fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). Several viral and cellular factors are required for a productive infection and for the development of liver disease. Some of these are long non-coding RNAs (lncRNAs) deregulated in infected cells. After HCV infection, the sequence and the structure of the viral RNA genome are sensed to activate interferon (IFN) synthesis and signaling pathways. These antiviral pathways regulate transcription of several cellular lncRNAs. Some of these are also deregulated in response to viral replication. Certain viral proteins and/or viral replication can activate transcription factors such as MYC, SP1, NRF2, or HIF1α that modulate the expression of additional cellular lncRNAs. Interestingly, several lncRNAs deregulated in HCV-infected cells described so far play proviral or antiviral functions by acting as positive or negative regulators of the IFN system, while others help in the development of liver cirrhosis and HCC. The study of the structure and mechanism of action of these lncRNAs may aid in the development of novel strategies to treat infectious and immune pathologies and liver diseases such as cirrhosis and HCC.
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Affiliation(s)
| | - Puri Fortes
- Department of Gene Therapy and Hepatology, Navarra Institute for Health Research (IdiSNA), Centro de Investigación Médica Aplicada, University of Navarra, Pamplona, Spain
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29
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Moriishi K. The potential of signal peptide peptidase as a therapeutic target for hepatitis C. Expert Opin Ther Targets 2017; 21:827-836. [DOI: 10.1080/14728222.2017.1369959] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Kohji Moriishi
- Department of Microbiology, Graduate School of Medical Science, University of Yamanashi, Yamanashi, Japan
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30
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Jackson CL, Walch L, Verbavatz JM. Lipids and Their Trafficking: An Integral Part of Cellular Organization. Dev Cell 2017; 39:139-153. [PMID: 27780039 DOI: 10.1016/j.devcel.2016.09.030] [Citation(s) in RCA: 102] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
An evolutionarily conserved feature of cellular organelles is the distinct phospholipid composition of their bounding membranes, which is essential to their identity and function. Within eukaryotic cells, two major lipid territories can be discerned, one centered on the endoplasmic reticulum and characterized by membranes with lipid packing defects, the other comprising plasma-membrane-derived organelles and characterized by membrane charge. We discuss how this cellular lipid organization is maintained, how lipid flux is regulated, and how perturbations in cellular lipid homeostasis can lead to disease.
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Affiliation(s)
- Catherine L Jackson
- Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, 75013 Paris, France.
| | - Laurence Walch
- Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, 75013 Paris, France
| | - Jean-Marc Verbavatz
- Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, 75013 Paris, France
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31
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Gluchowski NL, Becuwe M, Walther TC, Farese RV. Lipid droplets and liver disease: from basic biology to clinical implications. Nat Rev Gastroenterol Hepatol 2017; 14:343-355. [PMID: 28428634 PMCID: PMC6319657 DOI: 10.1038/nrgastro.2017.32] [Citation(s) in RCA: 396] [Impact Index Per Article: 56.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Lipid droplets are dynamic organelles that store neutral lipids during times of energy excess and serve as an energy reservoir during deprivation. Many prevalent metabolic diseases, such as the metabolic syndrome or obesity, often result in abnormal lipid accumulation in lipid droplets in the liver, also called hepatic steatosis. Obesity-related steatosis, or NAFLD in particular, is a major public health concern worldwide and is frequently associated with insulin resistance and type 2 diabetes mellitus. Here, we review the latest insights into the biology of lipid droplets and their role in maintaining lipid homeostasis in the liver. We also offer a perspective of liver diseases that feature lipid accumulation in these lipid storage organelles, which include NAFLD and viral hepatitis. Although clinical applications of this knowledge are just beginning, we highlight new opportunities for identifying molecular targets for treating hepatic steatosis and steatohepatitis.
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Affiliation(s)
- Nina L. Gluchowski
- Department of Genetics and Complex Diseases, Harvard T. H. Chan School of Public Health, 655 Huntington Avenue, Boston, Massachusetts 02115, USA.,Boston Children’s Hospital Department of Gastroenterology, Hepatology and Nutrition, 300 Longwood Avenue Boston, Massachusetts 02115, USA
| | - Michel Becuwe
- Department of Genetics and Complex Diseases, Harvard T. H. Chan School of Public Health, 655 Huntington Avenue, Boston, Massachusetts 02115, USA
| | - Tobias C. Walther
- Department of Genetics and Complex Diseases, Harvard T. H. Chan School of Public Health, 655 Huntington Avenue, Boston, Massachusetts 02115, USA.,Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue Boston, Massachusetts 02115, USA.,Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur Boston, Massachusetts 02115, USA.,Howard Hughes Medical Institute, Department of Genetics and Complex Diseases, Harvard T. H. Chan School of Public Health, 655 Huntington Avenue, Boston, Massachusetts 02115, USA
| | - Robert V. Farese
- Department of Genetics and Complex Diseases, Harvard T. H. Chan School of Public Health, 655 Huntington Avenue, Boston, Massachusetts 02115, USA.,Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue Boston, Massachusetts 02115, USA.,Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur Boston, Massachusetts 02115, USA
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32
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Fernández-Ponce C, Dominguez-Villar M, Muñoz-Miranda JP, Arbulo-Echevarria MM, Litrán R, Aguado E, García-Cozar F. Immune modulation by the hepatitis C virus core protein. J Viral Hepat 2017; 24:350-356. [PMID: 28092420 DOI: 10.1111/jvh.12675] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 12/22/2016] [Indexed: 12/14/2022]
Abstract
Hepatitis C virus (HCV) infection is currently the most important cause of chronic viral hepatitis in the world and one of the most frequent indications for liver transplantation. HCV uses different strategies to evade the innate and adaptive immune response, and this evasion plays a key role in determining viral persistence. Several HCV viral proteins have been described as immune modulators. In this review, we will focus on the effect of HCV nucleocapsid core protein in the function of immune cells and its correlation with the findings observed in HCV chronically infected patients. Effects on immune cell function related to both extracellular and intracellular HCV core localization will be considered. This review provides an updated perspective on the mechanisms involved in HCV evasion related to one single HCV protein, which could become a key tool in the development of new antiviral strategies able to control and/or eradicate HCV infection.
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Affiliation(s)
- C Fernández-Ponce
- Department of Biomedicine, Biotechnology and Public Health (Immunology), University of Cadiz and Institute of Biomedical Research Cádiz (INIBICA), Cadiz, Spain
| | - M Dominguez-Villar
- Department of Biomedicine, Biotechnology and Public Health (Immunology), University of Cadiz and Institute of Biomedical Research Cádiz (INIBICA), Cadiz, Spain.,Department of Neurology, Human Translational Immunology Program, Yale School of Medicine, 300 George St. 353D, New Haven, 06520, CT
| | - J P Muñoz-Miranda
- Department of Biomedicine, Biotechnology and Public Health (Immunology), University of Cadiz and Institute of Biomedical Research Cádiz (INIBICA), Cadiz, Spain
| | - M M Arbulo-Echevarria
- Department of Biomedicine, Biotechnology and Public Health (Immunology), University of Cadiz and Institute of Biomedical Research Cádiz (INIBICA), Cadiz, Spain
| | - R Litrán
- Department of Condensed Matter Physics, University of Cádiz, Puerto Real, Cádiz, Spain
| | - E Aguado
- Department of Biomedicine, Biotechnology and Public Health (Immunology), University of Cadiz and Institute of Biomedical Research Cádiz (INIBICA), Cadiz, Spain
| | - F García-Cozar
- Department of Biomedicine, Biotechnology and Public Health (Immunology), University of Cadiz and Institute of Biomedical Research Cádiz (INIBICA), Cadiz, Spain
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33
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Ferguson D, Zhang J, Davis MA, Helsley RN, Vedin LL, Lee RG, Crooke RM, Graham MJ, Allende DS, Parini P, Brown JM. The lipid droplet-associated protein perilipin 3 facilitates hepatitis C virus-driven hepatic steatosis. J Lipid Res 2016; 58:420-432. [PMID: 27941027 DOI: 10.1194/jlr.m073734] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Indexed: 12/18/2022] Open
Abstract
Hepatitis C virus (HCV) is an enveloped RNA virus responsible for 170 million cases of viral hepatitis worldwide. Over 50% of chronically infected HCV patients develop hepatic steatosis, and steatosis can be induced by expression of HCV core protein (core) alone. Additionally, core must associate with cytoplasmic lipid droplets (LDs) for steatosis development and viral particle assembly. Due to the importance of the LD as a key component of hepatic lipid storage and as a platform for HCV particle assembly, it seems this dynamic subcellular organelle is a gatekeeper in the pathogenesis of viral hepatitis. Here, we hypothesized that core requires the host LD scaffold protein, perilipin (PLIN)3, to induce hepatic steatosis. To test our hypothesis in vivo, we have studied core-induced hepatic steatosis in the absence or presence of antisense oligonucleotide-mediated knockdown of PLIN3. PLIN3 knockdown blunted HCV core-induced steatosis in transgenic mice fed either chow or a moderate fat diet. Collectively, our studies demonstrate that the LD scaffold protein, PLIN3, is essential for HCV core-induced hepatic steatosis and provide new insights into the pathogenesis of HCV.
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Affiliation(s)
- Daniel Ferguson
- Department of Cellular and Molecular Medicine, Cleveland Clinic Lerner Research Institute, Cleveland, OH.,Department of Pathology, Wake Forest School of Medicine, Winston-Salem, NC
| | - Jun Zhang
- Department of Pathology, Wake Forest School of Medicine, Winston-Salem, NC
| | - Matthew A Davis
- Department of Pathology, Wake Forest School of Medicine, Winston-Salem, NC
| | - Robert N Helsley
- Department of Cellular and Molecular Medicine, Cleveland Clinic Lerner Research Institute, Cleveland, OH
| | - Lise-Lotte Vedin
- Clinical Chemistry, Department of Laboratory Medicine, Karolinska Institute, Stockholm, Sweden
| | - Richard G Lee
- Clinical Chemistry, Department of Laboratory Medicine, Karolinska Institute, Stockholm, Sweden
| | - Rosanne M Crooke
- Clinical Chemistry, Department of Laboratory Medicine, Karolinska Institute, Stockholm, Sweden
| | - Mark J Graham
- Clinical Chemistry, Department of Laboratory Medicine, Karolinska Institute, Stockholm, Sweden
| | | | - Paolo Parini
- Clinical Chemistry, Department of Laboratory Medicine, Karolinska Institute, Stockholm, Sweden
| | - J Mark Brown
- Department of Cellular and Molecular Medicine, Cleveland Clinic Lerner Research Institute, Cleveland, OH
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34
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Bayer K, Banning C, Bruss V, Wiltzer-Bach L, Schindler M. Hepatitis C Virus Is Released via a Noncanonical Secretory Route. J Virol 2016; 90:10558-10573. [PMID: 27630244 PMCID: PMC5110177 DOI: 10.1128/jvi.01615-16] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 09/11/2016] [Indexed: 12/12/2022] Open
Abstract
We analyzed hepatitis C virus (HCV) morphogenesis using viral genomes encoding a mCherry-tagged E1 glycoprotein. HCV-E1-mCherry polyprotein expression, intracellular localization, and replication kinetics were comparable to those of untagged HCV, and E1-mCherry-tagged viral particles were assembled and released into cell culture supernatants. Expression and localization of structural E1 and nonstructural NS5A followed a temporospatial pattern with a succinct decrease in the number of replication complexes and the appearance of E1-mCherry punctae. Interaction of the structural proteins E1, Core, and E2 increased at E1-mCherry punctae in a time-dependent manner, indicating that E1-mCherry punctae represent assembled or assembling virions. E1-mCherry did not colocalize with Golgi markers. Furthermore, the bulk of viral glycoproteins within released particles revealed an EndoH-sensitive glycosylation pattern, indicating an absence of viral glycoprotein processing by the Golgi apparatus. In contrast, HCV-E1-mCherry trafficked with Rab9-positive compartments and inhibition of endosomes specifically suppressed HCV release. Our data suggest that assembled HCV particles are released via a noncanonical secretory route involving the endosomal compartment. IMPORTANCE The goal of this study was to shed light on the poorly understood trafficking and release routes of hepatitis C virus (HCV). For this, we generated novel HCV genomes which resulted in the production of fluorescently labeled viral particles. We used live-cell microscopy and other imaging techniques to follow up on the temporal dynamics of virus particle formation and trafficking in HCV-expressing liver cells. While viral particles and viral structural protein were found in endosomal compartments, no overlap of Golgi structures could be observed. Furthermore, biochemical and inhibitor-based experiments support a HCV release route which is distinguishable from canonical Golgi-mediated secretion. Since viruses hijack cellular pathways to generate viral progeny, our results point toward the possible existence of a not-yet-described cellular secretion route.
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Affiliation(s)
- Karen Bayer
- Institute of Virology, Helmholtz Zentrum München-German Research Center for Environmental Health, Munich, Germany
| | - Carina Banning
- Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany
| | - Volker Bruss
- Institute of Virology, Helmholtz Zentrum München-German Research Center for Environmental Health, Munich, Germany
| | - Linda Wiltzer-Bach
- University Hospital Tübingen, Institute for Medical Virology and Epidemiology of Viral Diseases, Tübingen, Germany
| | - Michael Schindler
- Institute of Virology, Helmholtz Zentrum München-German Research Center for Environmental Health, Munich, Germany
- University Hospital Tübingen, Institute for Medical Virology and Epidemiology of Viral Diseases, Tübingen, Germany
- Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany
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Abstract
Dengue virus affects hundreds of millions of people each year around the world, causing a tremendous social and economic impact on affected countries. The aim of this review is to summarize our current knowledge of the functions, structure, and interactions of the viral capsid protein. The primary role of capsid is to package the viral genome. There are two processes linked to this function: the recruitment of the viral RNA during assembly and the release of the genome during infection. Although particle assembly takes place on endoplasmic reticulum membranes, capsid localizes in nucleoli and lipid droplets. Why capsid accumulates in these locations during infection remains unknown. In this review, we describe available data and discuss new ideas on dengue virus capsid functions and interactions. We believe that a deeper understanding of how the capsid protein works during infection will create opportunities for novel antiviral strategies, which are urgently needed to control dengue virus infections.
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Affiliation(s)
- Laura A Byk
- Fundación Instituto Leloir-National Research Council for Science and Technology (CONICET), Buenos Aires 1405, Argentina;
| | - Andrea V Gamarnik
- Fundación Instituto Leloir-National Research Council for Science and Technology (CONICET), Buenos Aires 1405, Argentina;
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36
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Release of Infectious Hepatitis C Virus from Huh7 Cells Occurs via a trans-Golgi Network-to-Endosome Pathway Independent of Very-Low-Density Lipoprotein Secretion. J Virol 2016; 90:7159-70. [PMID: 27226379 PMCID: PMC4984645 DOI: 10.1128/jvi.00826-16] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Accepted: 05/23/2016] [Indexed: 12/12/2022] Open
Abstract
The release of infectious hepatitis C virus (HCV) particles from infected cells remains poorly characterized. We previously demonstrated that virus release is dependent on the endosomal sorting complex required for transport (ESCRT). Here, we show a critical role of trans-Golgi network (TGN)-endosome trafficking during the assembly, but principally the secretion, of infectious virus. This was demonstrated by both small interfering RNA (siRNA)-mediated silencing of TGN-associated adaptor proteins and a panel of dominant negative (DN) Rab GTPases involved in TGN-endosome trafficking steps. Importantly, interfering with factors critical for HCV release did not have a concomitant effect on secretion of triglycerides, ApoB, or ApoE, indicating that particles are likely released from Huh7 cells via pathways distinct from that of very-low-density lipoprotein (VLDL). Finally, we show that HCV NS2 perturbs TGN architecture, redistributing TGN membranes to closely associate with HCV core protein residing on lipid droplets. These findings support the notion that HCV hijacks TGN-endosome trafficking to facilitate particle assembly and release. Moreover, although essential for assembly and infectivity, the trafficking of mature virions is seemingly independent of host lipoproteins. IMPORTANCE The mechanisms by which infectious hepatitis C virus particles are assembled and released from the cell are poorly understood. We show that the virus subverts host cell trafficking pathways to effect the release of virus particles and disrupts the structure of the Golgi apparatus, a key cellular organelle involved in secretion. In addition, we demonstrate that the mechanisms used by the virus to exit the cell are distinct from those used by the cell to release lipoproteins, suggesting that the virus effects a unique modification to cellular trafficking pathways.
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37
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Iwasa S, Sato N, Wang CW, Cheng YH, Irokawa H, Hwang GW, Naganuma A, Kuge S. The Phospholipid:Diacylglycerol Acyltransferase Lro1 Is Responsible for Hepatitis C Virus Core-Induced Lipid Droplet Formation in a Yeast Model System. PLoS One 2016; 11:e0159324. [PMID: 27459103 PMCID: PMC4961368 DOI: 10.1371/journal.pone.0159324] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2015] [Accepted: 06/30/2016] [Indexed: 12/28/2022] Open
Abstract
Chronic infection with the hepatitis C virus frequently induces steatosis, which is a significant risk factor for liver pathogenesis. Steatosis is characterized by the accumulation of lipid droplets in hepatocytes. The structural protein core of the virus induces lipid droplet formation and localizes on the surface of the lipid droplets. However, the precise molecular mechanisms for the core-induced formation of lipid droplets remain elusive. Recently, we showed that the expression of the core protein in yeast as a model system could induce lipid droplet formation. In this study, we probed the cellular factors responsible for the formation of core-induced lipid-droplets in yeast cells. We demonstrated that one of the enzymes responsible for triglyceride synthesis, a phospholipid:diacylglycerol acyltransferase (Lro1), is required for the core-induced lipid droplet formation. While core proteins inhibit Lro1 degradation and alter Lro1 localization, the characteristic localization of Lro1 adjacent to the lipid droplets appeared to be responsible for the core-induced lipid droplet formation. RNA virus genomes have evolved using high mutation rates to maintain their ability to replicate. Our observations suggest a functional relationship between the core protein with hepatocytes and yeast cells. The possible interactions between core proteins and the endoplasmic reticulum membrane affect the mobilization of specific proteins.
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Affiliation(s)
- Shingo Iwasa
- Department of Microbiology, Faculty of Pharmaceutical Sciences, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi, 981–8558, Japan
| | - Naoko Sato
- Department of Microbiology, Faculty of Pharmaceutical Sciences, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi, 981–8558, Japan
- Laboratory of Molecular and Biochemical Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi, 980–8578, Japan
| | - Chao-Wen Wang
- Institute of Plant and Microbial Biology, Academia Sinica, Nangang, Taipei, 11529, Taiwan
| | - Yun-Hsin Cheng
- Institute of Plant and Microbial Biology, Academia Sinica, Nangang, Taipei, 11529, Taiwan
| | - Hayato Irokawa
- Department of Microbiology, Faculty of Pharmaceutical Sciences, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi, 981–8558, Japan
| | - Gi-Wook Hwang
- Laboratory of Molecular and Biochemical Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi, 980–8578, Japan
| | - Akira Naganuma
- Laboratory of Molecular and Biochemical Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi, 980–8578, Japan
| | - Shusuke Kuge
- Department of Microbiology, Faculty of Pharmaceutical Sciences, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi, 981–8558, Japan
- * E-mail: ;
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38
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Akil A, Peng J, Omrane M, Gondeau C, Desterke C, Marin M, Tronchère H, Taveneau C, Sar S, Briolotti P, Benjelloun S, Benjouad A, Maurel P, Thiers V, Bressanelli S, Samuel D, Bréchot C, Gassama-Diagne A. Septin 9 induces lipid droplets growth by a phosphatidylinositol-5-phosphate and microtubule-dependent mechanism hijacked by HCV. Nat Commun 2016; 7:12203. [PMID: 27417143 PMCID: PMC4947189 DOI: 10.1038/ncomms12203] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 06/07/2016] [Indexed: 01/09/2023] Open
Abstract
The accumulation of lipid droplets (LD) is frequently observed in hepatitis C virus (HCV) infection and represents an important risk factor for the development of liver steatosis and cirrhosis. The mechanisms of LD biogenesis and growth remain open questions. Here, transcriptome analysis reveals a significant upregulation of septin 9 in HCV-induced cirrhosis compared with the normal liver. HCV infection increases septin 9 expression and induces its assembly into filaments. Septin 9 regulates LD growth and perinuclear accumulation in a manner dependent on dynamic microtubules. The effects of septin 9 on LDs are also dependent on binding to PtdIns5P, which, in turn, controls the formation of septin 9 filaments and its interaction with microtubules. This previously undescribed cooperation between PtdIns5P and septin 9 regulates oleate-induced accumulation of LDs. Overall, our data offer a novel route for LD growth through the involvement of a septin 9/PtdIns5P signalling pathway.
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Affiliation(s)
- Abdellah Akil
- INSERM, Unité 1193, F-94800 Villejuif, France.,University of Paris-Sud, UMR-S 1193, F-94800 Villejuif, France.,Laboratoire des Hépatites Virales, Département de Virologie. Institut Pasteur du Maroc, BP 20360 Casablanca, Maroc.,Faculté des Sciences, Laboratoire de Biochimie-Immunologie, Univ. Mohammed V, Rabat, Maroc
| | - Juan Peng
- INSERM, Unité 1193, F-94800 Villejuif, France.,University of Paris-Sud, UMR-S 1193, F-94800 Villejuif, France.,DHU Hepatinov, Villejuif F-94800, France
| | - Mohyeddine Omrane
- INSERM, Unité 1193, F-94800 Villejuif, France.,University of Paris-Sud, UMR-S 1193, F-94800 Villejuif, France.,DHU Hepatinov, Villejuif F-94800, France
| | - Claire Gondeau
- INSERM U1183, Institute of Regenerative Medicine and Biotherapy, University of Montpellier, 34295 Montpellier, France.,Department of Hepato-Gastroenterology A, Hospital Saint Eloi, CHRU, 34295 Montpellier, France
| | | | - Mickaël Marin
- INSERM, Unité 1193, F-94800 Villejuif, France.,University of Paris-Sud, UMR-S 1193, F-94800 Villejuif, France
| | - Hélène Tronchère
- INSERM U1048, I2MC and Université Paul Sabatier, 31432 Toulouse, France
| | - Cyntia Taveneau
- Virologie Moléculaire et Structurale CNRS UPR 3296 - INRA UsC 1358, 91198 Gif-sur-Yvette, France
| | - Sokhavuth Sar
- INSERM, Unité 1193, F-94800 Villejuif, France.,University of Paris-Sud, UMR-S 1193, F-94800 Villejuif, France
| | - Philippe Briolotti
- INSERM U1183, Institute of Regenerative Medicine and Biotherapy, University of Montpellier, 34295 Montpellier, France.,Department of Hepato-Gastroenterology A, Hospital Saint Eloi, CHRU, 34295 Montpellier, France
| | - Soumaya Benjelloun
- Laboratoire des Hépatites Virales, Département de Virologie. Institut Pasteur du Maroc, BP 20360 Casablanca, Maroc
| | - Abdelaziz Benjouad
- Faculté des Sciences, Laboratoire de Biochimie-Immunologie, Univ. Mohammed V, Rabat, Maroc.,Univ. Internationale de Rabat, Sala Al Jadida, Maroc
| | - Patrick Maurel
- INSERM U1183, Institute of Regenerative Medicine and Biotherapy, University of Montpellier, 34295 Montpellier, France.,Department of Hepato-Gastroenterology A, Hospital Saint Eloi, CHRU, 34295 Montpellier, France
| | | | - Stéphane Bressanelli
- Virologie Moléculaire et Structurale CNRS UPR 3296 - INRA UsC 1358, 91198 Gif-sur-Yvette, France
| | - Didier Samuel
- INSERM, Unité 1193, F-94800 Villejuif, France.,University of Paris-Sud, UMR-S 1193, F-94800 Villejuif, France.,DHU Hepatinov, Villejuif F-94800, France.,AP-HP Hôpital Paul-Brousse, Centre Hépato-Biliaire, Villejuif F-94800, France
| | - Christian Bréchot
- INSERM, Unité 1193, F-94800 Villejuif, France.,University of Paris-Sud, UMR-S 1193, F-94800 Villejuif, France.,Institut Pasteur, 75724 Paris, France
| | - Ama Gassama-Diagne
- INSERM, Unité 1193, F-94800 Villejuif, France.,University of Paris-Sud, UMR-S 1193, F-94800 Villejuif, France.,DHU Hepatinov, Villejuif F-94800, France
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39
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Villareal VA, Fu D, Costello DA, Xie XS, Yang PL. Hepatitis C Virus Selectively Alters the Intracellular Localization of Desmosterol. ACS Chem Biol 2016; 11:1827-33. [PMID: 27128812 DOI: 10.1021/acschembio.6b00324] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Hepatitis C virus (HCV) increases intracellular desmosterol without affecting the steady-state abundance of other sterols, and the antiviral activity of inhibitors of desmosterol synthesis is suppressed by the addition of exogenous desmosterol. These observations suggest a model in which desmosterol has a specific function, direct or indirect, in HCV replication and that HCV alters desmosterol homeostasis to promote viral replication. Here, we use stimulated Raman scattering (SRS) microscopy in combination with isotopically labeled sterols to show that HCV causes desmosterol to accumulate in lipid droplets that are closely associated with the viral NS5A protein and that are visually distinct from the broad distribution of desmosterol in mock-infected cells and the more heterogeneous and disperse lipid droplets to which cholesterol traffics. Localization of desmosterol in NS5A-associated lipid droplets suggests that desmosterol may affect HCV replication via a direct mechanism. We anticipate that SRS microscopy and similar approaches can provide much needed tools to study the localization of specific lipid molecules in cellulo and in vivo.
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Affiliation(s)
- Valerie A. Villareal
- Department
of Microbiology and Immunobiology, Harvard Medical School, 77 Avenue
Louis Pasteur, Boston, Massachusetts 02115, United States
| | - Dan Fu
- Department
of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts, United States
| | - Deirdre A. Costello
- Department
of Microbiology and Immunobiology, Harvard Medical School, 77 Avenue
Louis Pasteur, Boston, Massachusetts 02115, United States
| | - Xiaoliang Sunney Xie
- Department
of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts, United States
| | - Priscilla L. Yang
- Department
of Microbiology and Immunobiology, Harvard Medical School, 77 Avenue
Louis Pasteur, Boston, Massachusetts 02115, United States
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40
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Kim GW, Lee SH, Cho H, Kim M, Shin EC, Oh JW. Hepatitis C Virus Core Protein Promotes miR-122 Destabilization by Inhibiting GLD-2. PLoS Pathog 2016; 12:e1005714. [PMID: 27366906 PMCID: PMC4930175 DOI: 10.1371/journal.ppat.1005714] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Accepted: 06/01/2016] [Indexed: 12/12/2022] Open
Abstract
The liver-specific microRNA miR-122, which has essential roles in liver development and metabolism, is a key proviral factor for hepatitis C virus (HCV). Despite its crucial role in the liver and HCV life cycle, little is known about the molecular mechanism of miR-122 expression regulation by HCV infection. Here, we show that the HCV core protein downregulates the abundance of miR-122 by promoting its destabilization via the inhibition of GLD-2, a non-canonical cytoplasmic poly(A) polymerase. The decrease in miR-122 expression resulted in the dysregulation of the known functions of miR-122, including its proviral activity for HCV. By high-throughput sequencing of small RNAs from human liver biopsies, we found that the 22-nucleotide (nt) prototype miR-122 is modified at its 3' end by 3'-terminal non-templated and templated nucleotide additions. Remarkably, the proportion of miR-122 isomers bearing a single nucleotide tail of any ribonucleotide decreased in liver specimens from patients with HCV. We found that these single-nucleotide-tailed miR-122 isomers display increased miRNA activity and stability over the 22-nt prototype miR-122 and that the 3'-terminal extension is catalyzed by the unique terminal nucleotidyl transferase activity of GLD-2, which is capable of adding any single ribonucleotide without preference of adenylate to the miR-122 3' end. The HCV core protein specifically inhibited GLD-2, and its interaction with GLD-2 in the cytoplasm was found to be responsible for miR-122 downregulation. Collectively, our results provide new insights into the regulatory role of the HCV core protein in controlling viral RNA abundance and miR-122 functions through miR-122 stability modulation.
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Affiliation(s)
- Geon-Woo Kim
- Department of Biotechnology, Yonsei University, Seoul, Korea
| | - Seung-Hoon Lee
- Department of Biotechnology, Yonsei University, Seoul, Korea
| | - Hee Cho
- Department of Biotechnology, Yonsei University, Seoul, Korea
| | - Minwoo Kim
- Department of Biotechnology, Yonsei University, Seoul, Korea
| | - Eui-Cheol Shin
- Laboratory of Immunology and Infectious Diseases, Graduate School of Medical Science and Engineering, KAIST, Daejeon, Korea
| | - Jong-Won Oh
- Department of Biotechnology, Yonsei University, Seoul, Korea
- * E-mail:
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41
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Meyers NL, Fontaine KA, Kumar GR, Ott M. Entangled in a membranous web: ER and lipid droplet reorganization during hepatitis C virus infection. Curr Opin Cell Biol 2016; 41:117-24. [PMID: 27240021 DOI: 10.1016/j.ceb.2016.05.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 05/04/2016] [Accepted: 05/05/2016] [Indexed: 12/19/2022]
Abstract
Hepatitis C virus (HCV) is a major cause of liver disease worldwide. To establish and maintain chronic infection, HCV extensively rearranges cellular organelles to generate distinct compartments for viral RNA replication and virion assembly. Here, we review our current knowledge of how HCV proliferates and remodels ER-derived membranes while preserving and expanding associated lipid droplets during viral infection. Unraveling the molecular mechanisms responsible for HCV-induced membrane reorganization will enhance our understanding of the HCV life-cycle, the associated liver pathology, and the biology of the ER:lipid droplet interface in general.
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Affiliation(s)
- Nathan L Meyers
- Gladstone Institutes, University of California San Francisco, 1650 Owens Street, San Francisco, CA 94941, United States
| | - Krystal A Fontaine
- Gladstone Institutes, University of California San Francisco, 1650 Owens Street, San Francisco, CA 94941, United States
| | - G Renuka Kumar
- Gladstone Institutes, University of California San Francisco, 1650 Owens Street, San Francisco, CA 94941, United States
| | - Melanie Ott
- Gladstone Institutes, University of California San Francisco, 1650 Owens Street, San Francisco, CA 94941, United States.
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42
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Champeimont R, Laine E, Hu SW, Penin F, Carbone A. Coevolution analysis of Hepatitis C virus genome to identify the structural and functional dependency network of viral proteins. Sci Rep 2016; 6:26401. [PMID: 27198619 PMCID: PMC4873791 DOI: 10.1038/srep26401] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 05/03/2016] [Indexed: 12/20/2022] Open
Abstract
A novel computational approach of coevolution analysis allowed us to reconstruct the protein-protein interaction network of the Hepatitis C Virus (HCV) at the residue resolution. For the first time, coevolution analysis of an entire viral genome was realized, based on a limited set of protein sequences with high sequence identity within genotypes. The identified coevolving residues constitute highly relevant predictions of protein-protein interactions for further experimental identification of HCV protein complexes. The method can be used to analyse other viral genomes and to predict the associated protein interaction networks.
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Affiliation(s)
- Raphaël Champeimont
- Sorbonne Universités, UPMC-Univ P6, CNRS, Laboratoire de Biologie Computationnelle et Quantitative - UMR 7238, 15 rue de l’Ecole de Médecine, 75006 Paris, France
| | - Elodie Laine
- Sorbonne Universités, UPMC-Univ P6, CNRS, Laboratoire de Biologie Computationnelle et Quantitative - UMR 7238, 15 rue de l’Ecole de Médecine, 75006 Paris, France
| | - Shuang-Wei Hu
- Sorbonne Universités, UPMC-Univ P6, CNRS, Laboratoire de Biologie Computationnelle et Quantitative - UMR 7238, 15 rue de l’Ecole de Médecine, 75006 Paris, France
| | - Francois Penin
- CNRS, UMR5086, Bases Moléculaires et Structurales des Systèmes Infectieux, Institut de Biologie et Chimie des Protéines, 7 Passage du Vercors, Cedex 07, F-69367 Lyon, France
- LABEX Ecofect, Université de Lyon, Lyon, France
| | - Alessandra Carbone
- Sorbonne Universités, UPMC-Univ P6, CNRS, Laboratoire de Biologie Computationnelle et Quantitative - UMR 7238, 15 rue de l’Ecole de Médecine, 75006 Paris, France
- Institut Universitaire de France, 75005, Paris, France
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43
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Abstract
Lipid droplets are the intracellular sites for neutral lipid storage. They are critical for lipid metabolism and energy homeostasis, and their dysfunction has been linked to many diseases. Accumulating evidence suggests that the roles lipid droplets play in biology are significantly broader than previously anticipated. Lipid droplets are the source of molecules important in the nucleus: they can sequester transcription factors and chromatin components and generate the lipid ligands for certain nuclear receptors. Lipid droplets have also emerged as important nodes for fatty acid trafficking, both inside the cell and between cells. In immunity, new roles for droplets, not directly linked to lipid metabolism, have been uncovered, with evidence that they act as assembly platforms for specific viruses and as reservoirs for proteins that fight intracellular pathogens. Until recently, knowledge about droplets in the nervous system has been minimal, but now there are multiple links between lipid droplets and neurodegeneration: many candidate genes for hereditary spastic paraplegia also have central roles in lipid-droplet formation and maintenance, and mitochondrial dysfunction in neurons can lead to transient accumulation of lipid droplets in neighboring glial cells, an event that may, in turn, contribute to neuronal damage. As the cell biology and biochemistry of lipid droplets become increasingly well understood, the next few years should yield many new mechanistic insights into these novel functions of lipid droplets.
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44
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Kao CC, Yi G, Huang HC. The core of hepatitis C virus pathogenesis. Curr Opin Virol 2016; 17:66-73. [PMID: 26851516 DOI: 10.1016/j.coviro.2016.01.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Revised: 01/05/2016] [Accepted: 01/14/2016] [Indexed: 02/06/2023]
Abstract
Capsid proteins form protective shells around viral genomes and mediate viral entry. However, many capsid proteins have additional and important roles for virus infection and in modulating cellular response to infection, with important consequences on pathogenesis. Infection by the Hepatitis C virus (HCV) can lead to liver steatosis, cirrhosis, and hepatocellular carcinoma. Herein, we focus on the role in pathogenesis of Core, the capsid protein of the HCV.
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Affiliation(s)
- C Cheng Kao
- Dept of Molecular & Cellular Biochemistry, Indiana University, Bloomington, IN 47405, United States.
| | - Guanghui Yi
- Dept of Molecular & Cellular Biochemistry, Indiana University, Bloomington, IN 47405, United States
| | - Hsuan-Cheng Huang
- Inst. of Biomedical Informatics, National Yang-Ming University, Taipei 11221, Taiwan
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45
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Zayas M, Long G, Madan V, Bartenschlager R. Coordination of Hepatitis C Virus Assembly by Distinct Regulatory Regions in Nonstructural Protein 5A. PLoS Pathog 2016; 12:e1005376. [PMID: 26727512 PMCID: PMC4699712 DOI: 10.1371/journal.ppat.1005376] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 12/09/2015] [Indexed: 12/19/2022] Open
Abstract
Hepatitis C virus (HCV) nonstructural protein (NS)5A is a RNA-binding protein composed of a N-terminal membrane anchor, a structured domain I (DI) and two intrinsically disordered domains (DII and DIII) interacting with viral and cellular proteins. While DI and DII are essential for RNA replication, DIII is required for assembly. How these processes are orchestrated by NS5A is poorly understood. In this study, we identified a highly conserved basic cluster (BC) at the N-terminus of DIII that is critical for particle assembly. We generated BC mutants and compared them with mutants that are blocked at different stages of the assembly process: a NS5A serine cluster (SC) mutant blocked in NS5A-core interaction and a mutant lacking the envelope glycoproteins (ΔE1E2). We found that BC mutations did not affect core-NS5A interaction, but strongly impaired core–RNA association as well as virus particle envelopment. Moreover, BC mutations impaired RNA-NS5A interaction arguing that the BC might be required for loading of core protein with viral RNA. Interestingly, RNA-core interaction was also reduced with the ΔE1E2 mutant, suggesting that nucleocapsid formation and envelopment are coupled. These findings argue for two NS5A DIII determinants regulating assembly at distinct, but closely linked steps: (i) SC-dependent recruitment of replication complexes to core protein and (ii) BC-dependent RNA genome delivery to core protein, triggering encapsidation that is tightly coupled to particle envelopment. These results provide a striking example how a single viral protein exerts multiple functions to coordinate the steps from RNA replication to the assembly of infectious virus particles. Hepatitis C virus (HCV) nonstructural protein (NS)5A is an enigmatic RNA-binding protein that appears to regulate the different steps from RNA replication to the assembly of infectious virus particles by yet unknown mechanisms. Assembly requires delivery of the viral RNA genome from the replication machinery to the capsid protein to ensure genome packaging into nucleocapsids that acquire a membranous envelope by budding into the lumen of the endoplasmic reticulum. In this study, we provide genetic and biochemical evidence that the viral nonstructural protein (NS)5A contains two regulatory determinants in its domain (D)III that orchestrate virus assembly at two closely linked steps: (i) recruitment of replication complexes to core protein requiring a serine cluster in the C-terminal region of DIII and (ii) RNA genome delivery to core protein requiring a basic cluster in the N-terminal region of DIII. This RNA transfer most likely triggers encapsidation, which is tightly coupled to particle envelopment. These results provide a striking example for a multi-purpose viral protein exerting several distinct functions in the viral replication cycle, thus reflecting genetic economy.
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Affiliation(s)
- Margarita Zayas
- Department for Infectious Diseases, Molecular Virology, Heidelberg University, Heidelberg, Germany
- * E-mail: (MZ); (RB)
| | - Gang Long
- Department for Infectious Diseases, Molecular Virology, Heidelberg University, Heidelberg, Germany
| | - Vanesa Madan
- Department for Infectious Diseases, Molecular Virology, Heidelberg University, Heidelberg, Germany
| | - Ralf Bartenschlager
- Department for Infectious Diseases, Molecular Virology, Heidelberg University, Heidelberg, Germany
- * E-mail: (MZ); (RB)
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46
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Abstract
RNAs are functionally diverse macromolecules whose proper functions rely strictly upon their correct tertiary structures. However, because of their high structural flexibility, correct folding of RNAs is challenging and slow. Therefore, cells and viruses encode a variety of RNA remodeling proteins, including helicases and RNA chaperones. In RNA viruses, these proteins are believed to play pivotal roles in all the processes involving viral RNAs during the life cycle. RNA helicases have been studied extensively for decades, whereas RNA chaperones, particularly virus-encoded RNA chaperones, are often overlooked. This review describes the activities of RNA chaperones encoded by RNA viruses, particularly the ones identified and characterized in recent years, and the functions of these proteins in different steps of viral life cycles, and presents an overview of this unique group of proteins.
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Affiliation(s)
- Jie Yang
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, China
| | - Hongjie Xia
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, China
| | - Qi Qian
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, China
| | - Xi Zhou
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, China.
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47
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Del Campo JA, Romero-Gómez M. Modulation of host lipid metabolism by hepatitis C virus: Role of new therapies. World J Gastroenterol 2015; 21:10776-10782. [PMID: 26478669 PMCID: PMC4600579 DOI: 10.3748/wjg.v21.i38.10776] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 07/07/2015] [Accepted: 09/14/2015] [Indexed: 02/06/2023] Open
Abstract
It is well established that hepatitis C virus (HCV) infection and replication relies on host lipid metabolism. HCV proteins interact and associate with lipid droplets to facilitate virion assembly and production. Besides, circulating infective particles are associated with very low-density lipoprotein. On the other hand, higher serum lipid levels have been associated with sustained viral response to pegylated interferon and ribavirin therapy in chronic HCV infection, suggesting a relevant role in viral clearance for host proteins. Host and viral genetic factors play an essential role in chronic infection. Lipid metabolism is hijacked by viral infection and could determine the success of viral replication. Recently development of direct acting antiviral agents has shown a very high efficacy (> 90%) in sustained viral response rates even for cirrhotic patients and most of the viral genotypes. HCV RNA clearance induced by Sofosbuvir has been associated with an increased concentration and size of the low-density lipoprotein particles. In this review, host genetic factors, viral factors and the interaction between them will be depicted to clarify the major issues involved in viral infection and lipid metabolism.
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48
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The Replacement of 10 Non-Conserved Residues in the Core Protein of JFH-1 Hepatitis C Virus Improves Its Assembly and Secretion. PLoS One 2015; 10:e0137182. [PMID: 26339783 PMCID: PMC4560444 DOI: 10.1371/journal.pone.0137182] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2015] [Accepted: 08/13/2015] [Indexed: 12/13/2022] Open
Abstract
Hepatitis C virus (HCV) assembly is still poorly understood. It is thought that trafficking of the HCV core protein to the lipid droplet (LD) surface is essential for its multimerization and association with newly synthesized HCV RNA to form the viral nucleocapsid. We carried out a mapping analysis of several complete HCV genomes of all genotypes, and found that the genotype 2 JFH-1 core protein contained 10 residues different from those of other genotypes. The replacement of these 10 residues of the JFH-1 strain sequence with the most conserved residues deduced from sequence alignments greatly increased virus production. Confocal microscopy of the modified JFH-1 strain in cell culture showed that the mutated JFH-1 core protein, C10M, was present mostly at the endoplasmic reticulum (ER) membrane, but not at the surface of the LDs, even though its trafficking to these organelles was possible. The non-structural 5A protein of HCV was also redirected to ER membranes and colocalized with the C10M core protein. Using a Semliki forest virus vector to overproduce core protein, we demonstrated that the C10M core protein was able to form HCV-like particles, unlike the native JFH-1 core protein. Thus, the substitution of a few selected residues in the JFH-1 core protein modified the subcellular distribution and assembly properties of the protein. These findings suggest that the early steps of HCV assembly occur at the ER membrane rather than at the LD surface. The C10M-JFH-1 strain will be a valuable tool for further studies of HCV morphogenesis.
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49
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Iglesias NG, Mondotte JA, Byk LA, De Maio FA, Samsa MM, Alvarez C, Gamarnik AV. Dengue Virus Uses a Non-Canonical Function of the Host GBF1-Arf-COPI System for Capsid Protein Accumulation on Lipid Droplets. Traffic 2015; 16:962-77. [PMID: 26031340 DOI: 10.1111/tra.12305] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Revised: 05/22/2015] [Accepted: 05/24/2015] [Indexed: 12/14/2022]
Abstract
Dengue viruses cause the most important human viral disease transmitted by mosquitoes. In recent years, a great deal has been learned about molecular details of dengue virus genome replication; however, little is known about genome encapsidation and the functions of the viral capsid protein. During infection, dengue virus capsid progressively accumulates around lipid droplets (LDs) by an unknown mechanism. Here, we examined the process by which the viral capsid is transported from the endoplasmic reticulum (ER) membrane, where the protein is synthesized, to LDs. Using different methods of intervention, we found that the GBF1-Arf1/Arf4-COPI pathway is necessary for capsid transport to LDs, while the process is independent of both COPII components and Golgi integrity. The transport was sensitive to Brefeldin A, while a drug resistant form of GBF1 was sufficient to restore capsid subcellular distribution in infected cells. The mechanism by which LDs gain or lose proteins is still an open question. Our results support a model in which the virus uses a non-canonical function of the COPI system for capsid accumulation on LDs, providing new ideas for antiviral strategies.
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Affiliation(s)
- Nestor G Iglesias
- Fundación Instituto Leloir-CONICET, Avenida Patricias Argentinas 435, Buenos Aires, 1405, Argentina
| | - Juan A Mondotte
- Fundación Instituto Leloir-CONICET, Avenida Patricias Argentinas 435, Buenos Aires, 1405, Argentina
| | - Laura A Byk
- Fundación Instituto Leloir-CONICET, Avenida Patricias Argentinas 435, Buenos Aires, 1405, Argentina
| | - Federico A De Maio
- Fundación Instituto Leloir-CONICET, Avenida Patricias Argentinas 435, Buenos Aires, 1405, Argentina
| | - Marcelo M Samsa
- Fundación Instituto Leloir-CONICET, Avenida Patricias Argentinas 435, Buenos Aires, 1405, Argentina
| | - Cecilia Alvarez
- Centro de Investigaciones en Bioquímica Clínica e Inmunología-CONICET, Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, UNC, 5000, Córdoba, Argentina
| | - Andrea V Gamarnik
- Fundación Instituto Leloir-CONICET, Avenida Patricias Argentinas 435, Buenos Aires, 1405, Argentina
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Abstract
Chronic hepatitis C virus (HCV) infection results in a progressive disease that may end in cirrhosis and, eventually, in hepatocellular carcinoma. In the last several years, tremendous progress has been made in understanding the HCV life cycle and in the development of small molecule compounds for the treatment of chronic hepatitis C. Nevertheless, the complete understanding of HCV assembly and particle release as well as the detailed characterization and structure of HCV particles is still missing. One of the most important events in the HCV assembly is the nucleocapsid formation which is driven by the core protein, that can oligomerize upon interaction with viral RNA, and is orchestrated by viral and host proteins. Despite a growing number of new factors involved in HCV assembly process, we do not know the three-dimensional structure of the core protein or its topology in the nucleocapsid. Since the core protein contains a hydrophobic C-terminal domain responsible for the binding to cellular membranes, the assembly pathway of HCV virions might proceed via coassembly at endoplasmic reticulum membranes. Recently, new mechanisms involving viral proteins and host factors in HCV particle formation and egress have been described. The present review aims to summarize the advances in our understanding of HCV assembly with an emphasis on the core protein as a structural component of virus particles that possesses the ability to interact with a variety of cellular components and is potentially an attractive target for the development of a novel class of anti-HCV agents.
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Affiliation(s)
- Katarzyna Gawlik
- Department of Immunology and Microbial Science, IMM-9, The Scripps Research Institute, 10550 N. Torrey Pines Rd., La Jolla, CA, 92037, USA
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