151
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The autophagy elongation complex (ATG5-12/16L1) positively regulates HCV replication and is required for wild-type membranous web formation. Sci Rep 2017; 7:40351. [PMID: 28067309 PMCID: PMC5220323 DOI: 10.1038/srep40351] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Accepted: 12/05/2016] [Indexed: 12/13/2022] Open
Abstract
Hepatitis C virus (HCV) infection induces intracellular membrane rearrangements, thus forming a membranous web (MW) in which HCV replication and assembly occur. The HCV-induced MW is primarily composed of double membrane vesicles (DMVs) transfused by multi-membrane vesicles. The autophagy machinery has been proposed to participate in the formation of such vesicles. However, no clear evidence has been found linking autophagy to the formation of these DMVs. In this study, we evaluated the role of the autophagy elongation complex (ATG5-12/16L1) in HCV replication and MW formation. Using a dominant negative form of ATG12 and an siRNA approach, we demonstrated that the ATG5-12 conjugate, but not LC3-II formation, is crucial for efficient viral replication. Furthermore, purification of HCV MW revealed the presence of ATG5-12 and ATG16L1 along with HCV nonstructural proteins. Interestingly, LC3 was not recruited along with the elongation complex to the site of viral replication. Finally, inhibition of the elongation complex, but not LC3, greatly impaired the formation of the wild-type MW phenotype. To our knowledge, this study provides the first evidence of the involvement of autophagy proteins in the formation of wild-type MWs.
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152
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Awad A, Gassama-Diagne A. PI3K/SHIP2/PTEN pathway in cell polarity and hepatitis C virus pathogenesis. World J Hepatol 2017; 9:18-29. [PMID: 28105255 PMCID: PMC5220268 DOI: 10.4254/wjh.v9.i1.18] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 09/10/2016] [Accepted: 11/02/2016] [Indexed: 02/06/2023] Open
Abstract
Hepatitis C virus (HCV) infects hepatocytes, polarized cells in the liver. Chronic HCV infection often leads to steatosis, fibrosis, cirrhosis and hepatocellular carcinoma, and it has been identified as the leading cause of liver transplantation worldwide. The HCV replication cycle is dependent on lipid metabolism and particularly an accumulation of lipid droplets in host cells. Phosphoinositides (PIs) are minor phospholipids enriched in different membranes and their levels are tightly regulated by specific PI kinases and phosphatases. PIs are implicated in a vast array of cellular responses that are central to morphogenesis, such as cytoskeletal changes, cytokinesis and the recruitment of downstream effectors to govern mechanisms involved in polarization and lumen formation. Important reviews of the literature identified phosphatidylinositol (PtdIns) 4-kinases, and their lipid products PtdIns(4)P, as critical regulators of the HCV life cycle. SH2-containing inositol polyphosphate 5-phosphatase (SHIP2), phosphoinositide 3-kinase (PI3K) and their lipid products PtdIns(3,4)P2 and PtdIns(3,4,5)P3, respectively, play an important role in the cell membrane and are key to the establishment of apicobasal polarity and lumen formation. In this review, we will focus on these new functions of PI3K and SHIP2, and their deregulation by HCV, causing a disruption of apicobasal polarity, actin organization and extracellular matrix assembly. Finally we will highlight the involvement of this pathway in the event of insulin resistance and nonalcoholic fatty liver disease related to HCV infection.
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153
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Wang H, Tai AW. Continuous de novo generation of spatially segregated hepatitis C virus replication organelles revealed by pulse-chase imaging. J Hepatol 2017; 66:55-66. [PMID: 27599826 PMCID: PMC5167665 DOI: 10.1016/j.jhep.2016.08.018] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 08/22/2016] [Accepted: 08/26/2016] [Indexed: 01/22/2023]
Abstract
BACKGROUND & AIMS Like all positive-sense RNA viruses, hepatitis C virus (HCV) induces host membrane alterations for its replication. In chronically infected cells, it is not known whether these viral replication organelles are being continually resupplied by newly synthesized viral proteins in situ, or whether they are generated de novo. Here we aimed to study temporal events in replication organelles formation and maturation. METHODS Here we use pulse-chase labeling in combination with confocal microscopy, correlative light electron microscopy and biochemical methods to identify temporally distinct populations of replication organelles in living cells and study the formation, morphogenesis as well as compositional and functional changes of replication organelles over time. RESULTS We found that HCV replication organelles are continuously generated de novo at spatially distinct sites from preformed ones. This process is accompanied by accumulated intracellular membrane alteration, increased cholesterol delivery, NS5A phosphorylation, and positive-strand RNA content, and by eventual association with HCV core protein around lipid droplets. Generation of spatially segregated foci requires viral NS5A and the host factors phosphatidylinositol 4-kinase and oxysterol-binding protein, while association of foci with lipid droplets requires cholesterol. CONCLUSIONS Our results reveal that HCV replication organelles are not static structures, but instead are continuously generated and dynamically change in composition and possibly also in function. LAY SUMMARY Hepatitis C virus replication membrane structures are continuously generated at spatially distinct sites. New replication organelles are different in composition, and possibly also in function, compared to old replication organelles.
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Affiliation(s)
- Hongliang Wang
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan
| | - Andrew W. Tai
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan
,Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan
,Medicine Service, Ann Arbor Veterans Administration Health System, Ann Arbor, Michigan
,Correspondence: Andrew W. Tai, University of Michigan, 6520 MSRB I SPC 5682, 1150 W Medical Center Dr, Ann Arbor, MI 48109-5682, Tel: (734) 764-2804, FAX: (734) 763-2535,
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154
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Abstract
Viruses use synthetic mechanism and organelles of the host cells to facilitate their replication and make new viruses. Host's ATP provides necessary energy. Hepatitis C virus (HCV) is a major cause of liver disease. Like other positive-strand RNA viruses, the HCV genome is thought to be synthesized by the replication complex, which consists of viral- and host cell-derived factors, in tight association with structurally rearranged vesicle-like cytoplasmic membranes. The virus-induced remodeling of subcellular membranes, which protect the viral RNA from nucleases in the cytoplasm, promotes efficient replication of HCV genome. The assembly of HCV particle involves interactions between viral structural and nonstructural proteins and pathways related to lipid metabolisms in a concerted fashion. Association of viral core protein, which forms the capsid, with lipid droplets appears to be a prerequisite for early steps of the assembly, which are closely linked with the viral genome replication. This review presents the recent progress in understanding the mechanisms for replication and assembly of HCV through its interactions with organelles or distinct organelle-like structures.
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Affiliation(s)
- Tetsuro Suzuki
- Department of Virology and Parasitology, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, 431-3192, Japan.
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155
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Mejdrová I, Chalupská D, Plačková P, Müller C, Šála M, Klíma M, Baumlová A, Hřebabecký H, Procházková E, Dejmek M, Strunin D, Weber J, Lee G, Matoušová M, Mertlíková-Kaiserová H, Ziebuhr J, Birkus G, Boura E, Nencka R. Rational Design of Novel Highly Potent and Selective Phosphatidylinositol 4-Kinase IIIβ (PI4KB) Inhibitors as Broad-Spectrum Antiviral Agents and Tools for Chemical Biology. J Med Chem 2016; 60:100-118. [PMID: 28004945 DOI: 10.1021/acs.jmedchem.6b01465] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Phosphatidylinositol 4-kinase IIIβ (PI4KB) is indispensable for the replication of various positive-sense single stranded RNA viruses, which hijack this cellular enzyme to remodel intracellular membranes of infected cells to set up the functional replication machinery. Therefore, the inhibition of this PI4K isoform leads to the arrest of viral replication. Here, we report on the synthesis of novel PI4KB inhibitors, which were rationally designed based on two distinct structural types of inhibitors that bind in the ATP binding side of PI4KB. These "hybrids" not only excel in outstanding inhibitory activity but also show high selectivity to PI4KB compared to other kinases. Thus, these compounds exert selective nanomolar or even subnanomolar activity against PI4KB as well as profound antiviral effect against hepatitis C virus, human rhinovirus, and coxsackievirus B3. Our crystallographic analysis unveiled the exact position of the side chains and explains their extensive contribution to the inhibitory activity.
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Affiliation(s)
- Ivana Mejdrová
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i, Gilead Sciences & IOCB Research Centre , Flemingovo nám. 2, 166 10 Prague 6, Czech Republic.,Department of Chemistry of Natural Compounds, Institute of Chemical Technology Prague , Technická 5, Prague 166 28, Czech Republic
| | - Dominika Chalupská
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i, Gilead Sciences & IOCB Research Centre , Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Pavla Plačková
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i, Gilead Sciences & IOCB Research Centre , Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Christin Müller
- Institute of Medical Virology, Justus Liebig University Giessen , Schubertstrasse 81, D-35392 Giessen, Germany
| | - Michal Šála
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i, Gilead Sciences & IOCB Research Centre , Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Martin Klíma
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i, Gilead Sciences & IOCB Research Centre , Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Adriana Baumlová
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i, Gilead Sciences & IOCB Research Centre , Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Hubert Hřebabecký
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i, Gilead Sciences & IOCB Research Centre , Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Eliška Procházková
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i, Gilead Sciences & IOCB Research Centre , Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Milan Dejmek
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i, Gilead Sciences & IOCB Research Centre , Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Dmytro Strunin
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i, Gilead Sciences & IOCB Research Centre , Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Jan Weber
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i, Gilead Sciences & IOCB Research Centre , Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Gary Lee
- Department of Chemistry of Natural Compounds, Institute of Chemical Technology Prague , Technická 5, Prague 166 28, Czech Republic
| | - Marika Matoušová
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i, Gilead Sciences & IOCB Research Centre , Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Helena Mertlíková-Kaiserová
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i, Gilead Sciences & IOCB Research Centre , Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - John Ziebuhr
- Institute of Medical Virology, Justus Liebig University Giessen , Schubertstrasse 81, D-35392 Giessen, Germany
| | - Gabriel Birkus
- Gilead Sciences, Inc. , 333 Lakeside Drive, Foster City, California 94404, United States
| | - Evzen Boura
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i, Gilead Sciences & IOCB Research Centre , Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Radim Nencka
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i, Gilead Sciences & IOCB Research Centre , Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
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156
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Tuning a cellular lipid kinase activity adapts hepatitis C virus to replication in cell culture. Nat Microbiol 2016; 2:16247. [PMID: 27991882 DOI: 10.1038/nmicrobiol.2016.247] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 11/04/2016] [Indexed: 12/30/2022]
Abstract
With a single exception, all isolates of hepatitis C virus (HCV) require adaptive mutations to replicate efficiently in cell culture. Here, we show that a major class of adaptive mutations regulates the activity of a cellular lipid kinase, phosphatidylinositol 4-kinase IIIα (PI4KA). HCV needs to stimulate PI4KA to create a permissive phosphatidylinositol 4-phosphate-enriched membrane microenvironment in the liver and in primary human hepatocytes (PHHs). In contrast, in Huh7 hepatoma cells, the virus must acquire loss-of-function mutations that prevent PI4KA overactivation. This adaptive mechanism is necessitated by increased PI4KA levels in Huh7 cells compared with PHHs, and is conserved across HCV genotypes. PI4KA-specific inhibitors promote replication of unadapted viral isolates and allow efficient replication of patient-derived virus in cell culture. In summary, this study has uncovered a long-sought mechanism of HCV cell-culture adaptation and demonstrates how a virus can adapt to changes in a cellular environment associated with tumorigenesis.
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157
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Medvedev R, Hildt E, Ploen D. Look who's talking-the crosstalk between oxidative stress and autophagy supports exosomal-dependent release of HCV particles. Cell Biol Toxicol 2016; 33:211-231. [PMID: 27987184 DOI: 10.1007/s10565-016-9376-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Accepted: 12/04/2016] [Indexed: 12/12/2022]
Abstract
Autophagy is a highly conserved and regulated intracellular lysosomal degradation pathway that is essential for cell survival. Dysregulation has been linked to the development of various human diseases, including neurodegeneration and tumorigenesis, infection, and aging. Besides, many viruses hijack the autophagosomal pathway to support their life cycle. The hepatitis C virus (HCV), a major cause of chronic liver diseases worldwide, has been described to induce autophagy. The autophagosomal pathway can be further activated in response to elevated levels of reactive oxygen species (ROS). HCV impairs the Nrf2/ARE-dependent induction of ROS-detoxifying enzymes by a so far unprecedented mechanism. In line with this, this review aims to discuss the relevance of HCV-dependent elevated ROS levels for the induction of autophagy as a result of the impaired Nrf2 signaling and the described crosstalk between p62 and the Nrf2/Keap1 signaling pathway. Moreover, autophagy is functionally connected to the endocytic pathway as components of the endosomal trafficking are involved in the maturation of autophagosomes. The release of HCV particles is still not fully understood. Recent studies suggest an involvement of exosomes that originate from the endosomal pathway in viral release. In line with this, it is tempting to speculate whether HCV-dependent elevated ROS levels induce autophagy to support exosome-mediated release of viral particles. Based on recent findings, in this review, we will further highlight the impact of HCV-induced autophagy and its interplay with the endosomal pathway as a novel mechanism for the release of HCV particles.
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Affiliation(s)
- Regina Medvedev
- Department of Virology, Paul-Ehrlich-Institut, Paul-Ehrlich-Straße 51-59, 63225, Langen, Germany
| | - Eberhard Hildt
- Department of Virology, Paul-Ehrlich-Institut, Paul-Ehrlich-Straße 51-59, 63225, Langen, Germany.,Deutsches Zentrum für Infektionsforschung (DZIF), Gießen, Marburg, Langen, Germany
| | - Daniela Ploen
- Department of Virology, Paul-Ehrlich-Institut, Paul-Ehrlich-Straße 51-59, 63225, Langen, Germany.
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158
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McPhail JA, Ottosen EH, Jenkins ML, Burke JE. The Molecular Basis of Aichi Virus 3A Protein Activation of Phosphatidylinositol 4 Kinase IIIβ, PI4KB, through ACBD3. Structure 2016; 25:121-131. [PMID: 27989622 DOI: 10.1016/j.str.2016.11.016] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 10/19/2016] [Accepted: 11/18/2016] [Indexed: 01/12/2023]
Abstract
Phosphatidylinositol 4-kinase III beta (PI4KIIIβ) is an essential enzyme in mediating membrane transport, and plays key roles in facilitating viral infection. Many pathogenic positive-sense single-stranded RNA viruses activate PI4KIIIβ to generate phosphatidylinositol 4-phosphate (PI4P)-enriched organelles for viral replication. The molecular basis for PI4KIIIβ activation during viral infection has remained largely unclear. We describe the biochemical reconstitution and characterization of the complex of PI4KIIIβ with the Golgi protein Acyl-coenzyme A binding domain containing protein 3 (ACBD3) and Aichi virus 3A protein on membranes. We find that 3A directly activates PI4KIIIβ, and this activation is sensitized by ACBD3. The interfaces between PI4KIIIβ-ACBD3 and ACBD3-3A were mapped with hydrogen-deuterium exchange mass spectrometry (HDX-MS). Determination of the crystal structure of the ACBD3 GOLD domain revealed a unique N terminus that mediates the interaction with 3A. Rationally designed complex-disrupting mutations in both ACBD3 and PI4KIIIβ completely abrogated the sensitization of 3A activation by ACBD3.
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Affiliation(s)
- Jacob A McPhail
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8P 5C2, Canada
| | - Erik H Ottosen
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8P 5C2, Canada
| | - Meredith L Jenkins
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8P 5C2, Canada
| | - John E Burke
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8P 5C2, Canada.
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159
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Costello DA, Villareal VA, Yang PL. Desmosterol Increases Lipid Bilayer Fluidity during Hepatitis C Virus Infection. ACS Infect Dis 2016; 2:852-862. [PMID: 27933788 PMCID: PMC5161114 DOI: 10.1021/acsinfecdis.6b00086] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Hepatitis C virus (HCV) uniquely affects desmosterol homeostasis by increasing its intracellular abundance and affecting its localization. These effects are important for productive viral replication because the inhibition of desmosterol synthesis has an antiviral effect that can be rescued by the addition of exogenous desmosterol. Here, we use subgenomic replicons to show that desmosterol has a major effect on the replication of HCV JFH1 RNA. Fluorescence recovery after photobleaching (FRAP) experiments performed with synthetic supported lipid bilayers demonstrate that the substitution of desmosterol for cholesterol significantly increases the lipid bilayer fluidity, especially in the presence of saturated phospholipids and ceramides. We demonstrate using LC-MS that desmosterol is abundant in the membranes upon which genome replication takes place and that supported lipid bilayers derived from these specialized membranes also exhibit significantly higher fluidity compared to that of negative control membranes isolated from cells lacking HCV. Together, these data suggest a model in which the fluidity-promoting effects of desmosterol on lipid bilayers play a crucial role in the extensive membrane remodeling that takes place in the endoplasmic reticulum during HCV infection. We anticipate that the supported lipid bilayer system described can provide a useful model system in which to interrogate the effects of lipid structure and composition on the biophysical properties of lipid membranes as well as their function in viral processes such as genome replication.
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Affiliation(s)
- Deirdre A. Costello
- Department of Microbiology and Immunobiology, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, U.S.A
| | - Valerie A. Villareal
- Department of Microbiology and Immunobiology, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, U.S.A
| | - Priscilla L. Yang
- Department of Microbiology and Immunobiology, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, U.S.A
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160
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Miyamura T, Lemon SM, Walker CM, Wakita T. The HCV Replicase Complex and Viral RNA Synthesis. HEPATITIS C VIRUS I 2016. [PMCID: PMC7122888 DOI: 10.1007/978-4-431-56098-2_8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Replication of hepatitis C virus (HCV) is tightly linked to membrane alterations designated the membranous web, harboring the viral replicase complex. In this chapter we describe the morphology and 3D architecture of the HCV-induced replication organelles, mainly consisting of double membrane vesicles, which are generated by a concerted action of the nonstructural proteins NS3 to NS5B. Recent studies have furthermore identified a number of host cell proteins and lipids contributing to the biogenesis of the membranous web, which are discussed in this chapter. Viral RNA synthesis is tightly associated with these membrane alterations and mainly driven by the viral RNA dependent RNA polymerase NS5B. We summarize our current knowledge of the structure and function of NS5B, the role of cis-acting replication elements at the termini of the genome in regulating RNA synthesis and the contribution of additional viral and host factors to viral RNA synthesis, which is still ill defined.
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Affiliation(s)
- Tatsuo Miyamura
- National Institute of Infectious Diseases, Tokyo, Tokyo Japan
| | - Stanley M. Lemon
- Departments of Medicine and Microbiology & Immunology , The University of North Carolina, Chapel Hill, North Carolina USA
| | - Christopher M. Walker
- Center for Vaccines and Immunity, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio USA
| | - Takaji Wakita
- National Institute of Infectious Diseases, Tokyo, Tokyo Japan
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161
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Abstract
Replication of positive-strand RNA viruses occurs in tight association with reorganized host cell membranes. In a concerted fashion, viral and cellular factors generate distinct organelle-like structures, designated viral replication factories. These virus-induced compartments promote highly efficient genome replication, allow spatiotemporal coordination of the different steps of the viral replication cycle, and protect viral RNA from the hostile cytoplasmic environment. The combined use of ultrastructural and functional studies has greatly increased our understanding of the architecture and biogenesis of viral replication factories. Here, we review common concepts and distinct differences in replication organelle morphology and biogenesis within the Flaviviridae family, exemplified by dengue virus and hepatitis C virus. We discuss recent progress made in our understanding of the complex interplay between viral determinants and subverted cellular membrane homeostasis in biogenesis and maintenance of replication factories of this virus family.
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Affiliation(s)
- David Paul
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, 69120 Heidelberg, Germany; ,
| | - Ralf Bartenschlager
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, 69120 Heidelberg, Germany; , .,Division of Virus-Associated Carcinogenesis, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
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162
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Affinity Purification of the Hepatitis C Virus Replicase Identifies Valosin-Containing Protein, a Member of the ATPases Associated with Diverse Cellular Activities Family, as an Active Virus Replication Modulator. J Virol 2016; 90:9953-9966. [PMID: 27558430 DOI: 10.1128/jvi.01140-16] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 08/19/2016] [Indexed: 12/11/2022] Open
Abstract
Like almost all of the positive-strand RNA viruses, hepatitis C virus (HCV) induces host intracellular membrane modification to form the membrane-bound viral replication complex (RC), within which viral replicases amplify the viral RNA genome. Despite accumulated information about how HCV co-opts host factors for viral replication, our knowledge of the molecular mechanisms by which viral proteins hijack host factors for replicase assembly has only begun to emerge. Purification of the viral replicase and identification of the replicase-associated host factors to dissect their roles in RC biogenesis will shed light on the molecular mechanisms of RC assembly. To purify the viral replicase in the context of genuine viral replication, we developed an HCV subgenomic replicon system in which two different affinity tags were simultaneously inserted in frame into HCV NS5A and NS5B. After solubilizing the replicon cells, we purified the viral replicase by two-step affinity purification and identified the associated host factors by mass spectrometry. We identified valosin-containing protein (VCP), a member of the ATPases associated with diverse cellular activities (AAA+ATPase) family, as an active viral replication modulator whose ATPase activity is required for viral replication. A transient replication assay indicated that VCP is involved mainly in viral genome amplification. VCP associated with viral replicase and colocalized with a viral RC marker. Further, in an HCV replicase formation surrogate system, abolishing VCP function resulted in aberrant distribution of HCV NS5A. We propose that HCV may co-opt a host AAA+ATPase for its replicase assembly. IMPORTANCE Almost all of the positive-strand RNA viruses share a replication strategy in which viral proteins modify host membranes to form the membrane-associated viral replicase. Viruses hijack host factors to facilitate this energy-unfavorable process. Understanding of this fundamental process is hampered by the challenges of purifying the replicase because of the technical difficulties involved. In this study, we developed an HCV subgenomic replicon system in which two different affinity tags were simultaneously inserted in frame into two replicase components. Using this dual-affinity-tagged replicon system, we purified the viral replicase and identified valosin-containing protein (VCP) AAA+ATPase as a pivotal viral replicase-associated host factor that is required for viral genome replication. Abolishing VCP function resulted in aberrant viral protein distribution. We propose that HCV hijacks a host AAA+ATPase for its replicase assembly. Understanding the molecular mechanism of VCP regulates viral replicase assembly may lead to novel antiviral strategies targeting the most conserved viral replication step.
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163
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Martín-Acebes MA, Vázquez-Calvo Á, Saiz JC. Lipids and flaviviruses, present and future perspectives for the control of dengue, Zika, and West Nile viruses. Prog Lipid Res 2016; 64:123-137. [PMID: 27702593 DOI: 10.1016/j.plipres.2016.09.005] [Citation(s) in RCA: 101] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Revised: 08/17/2016] [Accepted: 09/16/2016] [Indexed: 02/06/2023]
Abstract
Flaviviruses are emerging arthropod-borne pathogens that cause life-threatening diseases such as yellow fever, dengue, West Nile encephalitis, tick-borne encephalitis, Kyasanur Forest disease, tick-borne encephalitis, or Zika disease. This viral genus groups >50 viral species of small enveloped plus strand RNA virus that are phylogenetically closely related to hepatitis C virus. Importantly, the flavivirus life cycle is intimately associated to host cell lipids. Along this line, flaviviruses rearrange intracellular membranes from the endoplasmic-reticulum of the infected cells to develop adequate platforms for viral replication and particle biogenesis. Moreover, flaviviruses dramatically orchestrate a profound reorganization of the host cell lipid metabolism to create a favorable environment for viral multiplication. Consistently, recent work has shown the importance of specific lipid classes in flavivirus infections. For instances, fatty acid synthesis is linked to viral replication, phosphatidylserine and phosphatidylethanolamine are involved on the entry of flaviviruses, sphingolipids (ceramide and sphingomyelin) play a key role on virus assembly and pathogenesis, and cholesterol is essential for innate immunity evasion in flavivirus-infected cells. Here, we revise the current knowledge on the interactions of the flaviviruses with the cellular lipid metabolism to identify potential targets for future antiviral development aimed to combat these relevant health-threatening pathogens.
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Affiliation(s)
- Miguel A Martín-Acebes
- Department of Biotechnology, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Carretera de A Coruña km 7.5, 28040 Madrid, Spain.
| | - Ángela Vázquez-Calvo
- Department of Biotechnology, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Carretera de A Coruña km 7.5, 28040 Madrid, Spain
| | - Juan-Carlos Saiz
- Department of Biotechnology, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Carretera de A Coruña km 7.5, 28040 Madrid, Spain
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164
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Human Choline Kinase-α Promotes Hepatitis C Virus RNA Replication through Modulation of Membranous Viral Replication Complex Formation. J Virol 2016; 90:9075-95. [PMID: 27489281 PMCID: PMC5044849 DOI: 10.1128/jvi.00960-16] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Accepted: 07/20/2016] [Indexed: 12/19/2022] Open
Abstract
UNLABELLED Hepatitis C virus (HCV) infection reorganizes cellular membranes to create an active viral replication site named the membranous web (MW). The role that human choline kinase-α (hCKα) plays in HCV replication remains elusive. Here, we first showed that hCKα activity, not the CDP-choline pathway, promoted viral RNA replication. Confocal microscopy and subcellular fractionation of HCV-infected cells revealed that a small fraction of hCKα colocalized with the viral replication complex (RC) on the endoplasmic reticulum (ER) and that HCV infection increased hCKα localization to the ER. In the pTM-NS3-NS5B model, NS3-NS5B expression increased the localization of the wild-type, not the inactive D288A mutant, hCKα on the ER, and hCKα activity was required for effective trafficking of hCKα and NS5A to the ER. Coimmunoprecipitation showed that hCKα was recruited onto the viral RC presumably through its binding to NS5A domain 1 (D1). hCKα silencing or treatment with CK37, an hCKα activity inhibitor, abolished HCV-induced MW formation. In addition, hCKα depletion hindered NS5A localization on the ER, interfered with NS5A and NS5B colocalization, and mitigated NS5A-NS5B interactions but had no apparent effect on NS5A-NS4B and NS4B-NS5B interactions. Nevertheless, hCKα activity was not essential for the binding of NS5A to hCKα or NS5B. These findings demonstrate that hCKα forms a complex with NS5A and that hCKα activity enhances the targeting of the complex to the ER, where hCKα protein, not activity, mediates NS5A binding to NS5B, thereby promoting functional membranous viral RC assembly and viral RNA replication. IMPORTANCE HCV infection reorganizes the cellular membrane to create an active viral replication site named the membranous web (MW). Here, we report that human choline kinase-α (hCKα) acts as an essential host factor for HCV RNA replication. A fraction of hCKα colocalizes with the viral replication complex (RC) on the endoplasmic reticulum (ER) in HCV-infected cells. NS3-NS5B expression increases ER localization of wild-type, but not D288A mutant, hCKα, and hCKα activity facilitates the transport of itself and NS5A to the ER. Silencing or inactivation of hCKα abrogates MW formation. Moreover, hCKα is recruited by NS5A independent of hCKα activity, presumably through binding to NS5A D1. hCKα activity then mediates the ER targeting of the hCKα-NS5A complex. On the ER membrane, hCKα protein, per se, induces NS5A binding to NS5B, thereby promoting membranous RC formation and viral RNA replication. Our study may benefit the development of hCKα-targeted anti-HCV therapeutics.
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Tyrphostin AG1478 Inhibits Encephalomyocarditis Virus and Hepatitis C Virus by Targeting Phosphatidylinositol 4-Kinase IIIα. Antimicrob Agents Chemother 2016; 60:6402-6. [PMID: 27480860 DOI: 10.1128/aac.01331-16] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 07/27/2016] [Indexed: 02/07/2023] Open
Abstract
Encephalomyocarditis virus (EMCV), like hepatitis C virus (HCV), requires phosphatidylinositol 4-kinase IIIα (PI4KA) for genome replication. Here, we demonstrate that tyrphostin AG1478, a known epidermal growth factor receptor (EGFR) inhibitor, also inhibits PI4KA activity, both in vitro and in cells. AG1478 impaired replication of EMCV and HCV but not that of an EMCV mutant previously shown to escape PI4KA inhibition. This work uncovers novel cellular and antiviral properties of AG1478, a compound previously regarded only as a cancer chemotherapy agent.
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Hepatitis C Virus-Induced Upregulation of MicroRNA miR-146a-5p in Hepatocytes Promotes Viral Infection and Deregulates Metabolic Pathways Associated with Liver Disease Pathogenesis. J Virol 2016; 90:6387-6400. [PMID: 27147737 DOI: 10.1128/jvi.00619-16] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 04/23/2016] [Indexed: 12/12/2022] Open
Abstract
UNLABELLED Hepatitis C virus (HCV)-induced chronic liver disease is a leading cause of hepatocellular carcinoma (HCC). However, the molecular mechanisms underlying HCC development following chronic HCV infection remain poorly understood. MicroRNAs (miRNAs) play an important role in homeostasis within the liver, and deregulation of miRNAs has been associated with liver disease, including HCC. While host miRNAs are essential for HCV replication, viral infection in turn appears to induce alterations of intrahepatic miRNA networks. Although the cross talk between HCV and liver cell miRNAs most likely contributes to liver disease pathogenesis, the functional involvement of miRNAs in HCV-driven hepatocyte injury and HCC remains elusive. Here we combined a hepatocyte-like cell-based model system, high-throughput small RNA sequencing, computational analysis, and functional studies to investigate HCV-miRNA interactions that may contribute to liver disease and HCC. Profiling analyses indicated that HCV infection differentially regulated the expression of 72 miRNAs by at least 2-fold, including miRNAs that were previously described to target genes associated with inflammation, fibrosis, and cancer development. Further investigation demonstrated that the miR-146a-5p level was consistently increased in HCV-infected hepatocyte-like cells and primary human hepatocytes, as well as in liver tissue from HCV-infected patients. Genome-wide microarray and computational analyses indicated that miR-146a-5p overexpression modulates pathways that are related to liver disease and HCC development. Furthermore, we showed that miR-146a-5p has a positive impact on late steps of the viral replication cycle, thereby increasing HCV infection. Collectively, our data indicate that the HCV-induced increase in miR-146a-5p expression both promotes viral infection and is relevant for pathogenesis of liver disease. IMPORTANCE HCV is a leading cause of chronic liver disease and cancer. However, how HCV induces liver cancer remains poorly understood. There is accumulating evidence that a viral cure does not eliminate the risk for HCC development. Thus, there is an unmet medical need to develop novel approaches to predict and prevent virus-induced HCC. miRNA expression is known to be deregulated in liver disease and cancer. Furthermore, miRNAs are essential for HCV replication, and HCV infection alters miRNA expression. However, how miRNAs contribute to HCV-driven pathogenesis remains elusive. Here we show that HCV induces miRNAs that may contribute to liver injury and carcinogenesis. The miR-146a-5p level was consistently increased in different cell-based models of HCV infection and in HCV patient-derived liver tissue. Furthermore, miR-146a-5p increased HCV infection. Collectively, our data are relevant to understanding viral pathogenesis and may open perspectives for novel biomarkers and prevention of virus-induced liver disease and HCC.
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Loundras EA, Herod MR, Harris M, Stonehouse NJ. Foot-and-mouth disease virus genome replication is unaffected by inhibition of type III phosphatidylinositol-4-kinases. J Gen Virol 2016; 97:2221-2230. [PMID: 27323707 DOI: 10.1099/jgv.0.000527] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Foot-and-mouth disease virus (FMDV) causes economically damaging infections of cloven-hooved animals, with outbreaks resulting in large financial losses to the agricultural industry. Due to the highly contagious nature of FMDV, research with infectious virus is restricted to a limited number of key facilities worldwide. FMDV sub-genomic replicons are therefore important tools for the study of viral translation and genome replication. The type III phosphatidylinositol-4-kinases (PI4Ks) are a family of enzymes that plays a key role in the production of replication complexes (viral factories) of a number of positive-sense RNA viruses and represents a potential target for novel pan-viral therapeutics. Here, we investigated whether type III PI4Ks also play a role in the FMDV life cycle, using a combination of FMDV sub-genomic replicons and bicistronic internal ribosome entry site (IRES)-containing reporter plasmids. We demonstrated that replication of the FMDV replicon was unaffected by inhibitors of either PI4KIIIα or PI4KIIIβ. However, PIK93, an inhibitor previously demonstrated to target PI4KIIIβ, did inhibit IRES-mediated protein translation. Consistent with this, cells transfected with FMDV replicons did not exhibit elevated levels of phosphatidylinositol-4-phosphate lipids. These results are therefore supportive of the hypothesis that FMDV genome replication does not require type III PI4K activity and does not activate these kinases.
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Affiliation(s)
- Eleni-Anna Loundras
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Morgan R Herod
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - 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
| | - Nicola J Stonehouse
- 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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Cell-death-inducing DFFA-like Effector B Contributes to the Assembly of Hepatitis C Virus (HCV) Particles and Interacts with HCV NS5A. Sci Rep 2016; 6:27778. [PMID: 27282740 PMCID: PMC4901263 DOI: 10.1038/srep27778] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 05/23/2016] [Indexed: 12/12/2022] Open
Abstract
Hepatitis C virus (HCV) uses components of the very-low-density lipoprotein (VLDL) pathway for assembly/release. We previously reported that hepatocyte nuclear factor 4α (HNF4α) participates in HCV assembly/release through downstream factors those participate in VLDL assembly/secretion. Cell-death-inducing DFFA-like effector B (CIDEB) is an important regulator of the VLDL pathway. CIDEB is required for entry of HCV particles from cell culture (HCVcc), but the effects of CIDEB on the post-entry steps of the HCV lifecycle are unclear. In the present study, we determined that CIDEB is required for HCV assembly in addition to HCVcc entry. Furthermore, CIDEB interacts with the HCV NS5A protein, and the N terminus of CIDEB and the domain I of NS5A are involved in this interaction. Moreover, CIDEB silencing impairs the association of apolipoprotein E (ApoE) with HCV particles. Interestingly, CIDEB is also required for the post-entry stages of the dengue virus (DENV) life cycle. Collectively, these results indicate that CIDEB is a new host factor that is involved in HCV assembly, presumably by interacting with viral protein, providing new insight into the exploitation of the VLDL regulator CIDEB by HCV.
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169
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Ravindran MS, Bagchi P, Cunningham CN, Tsai B. Opportunistic intruders: how viruses orchestrate ER functions to infect cells. Nat Rev Microbiol 2016; 14:407-420. [PMID: 27265768 PMCID: PMC5272919 DOI: 10.1038/nrmicro.2016.60] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Viruses exploit the functions of the endoplasmic reticulum (ER) to promote both early and later stages of their life cycle, including entry, translation, replication, assembly, morphogenesis and egress. This observation reveals a shared principle that underlies virus–host cell relationships. Viral entry often requires disassembly of the incoming virus particle. This is best exemplified in the case of polyomavirus entry, in which ER-associated machineries are hijacked to disassemble the virus and promote entry to the cytosol en route to the nucleus. Many enveloped viruses, such as HIV and influenza virus, co-opt the ER-associated protein biosynthetic machinery to translate their genome and produce structural proteins that are necessary for the formation of virus particles and non-structural proteins that are essential during genome replication. Replication of the viral genome, particularly for positive-sense RNA ((+)RNA) viruses including hepatitis C virus (HCV), dengue virus (DENV) and West Nile virus (WNV), occurs in virus-induced membranous structures that are most often derived from the ER. The formation of these structures requires morphological changes to the ER membrane, involving membrane rearrangements that are induced by viral non-structural proteins that are targeted to the ER. As virus assembly is often coupled to genome replication, the assembly process frequently relies on the ER membrane. This strategy is seen for both RNA and DNA viruses. Morphogenesis of assembled virus particles can also take advantage of the ER. This is best observed in the non-enveloped rotavirus, for which a transient enveloped intermediate is converted to the mature and infectious particle in the lumen of the ER. After maturation in the ER, progeny virus particles egress the host through the ER-dependent secretory pathway, which provides a physical conduit to the extracellular environment. The overall observations that the ER actively promotes all steps of viral infection have therapeutic implications. The development of chemical inhibitors of selective ER-associated components is emerging as a potential avenue of antiviral therapy, provided that these inhibitors have minimal toxicity to the host cell.
Many host structures are vital for viral infection and the endoplasmic reticulum (ER), in particular, is essential. In this Review, Tsai and colleagues highlight examples of subversion of the ER by diverse viruses to promote all stages of their life cycle, from entry to egress. Viruses subvert the functions of their host cells to replicate and form new viral progeny. The endoplasmic reticulum (ER) has been identified as a central organelle that governs the intracellular interplay between viruses and hosts. In this Review, we analyse how viruses from vastly different families converge on this unique intracellular organelle during infection, co-opting some of the endogenous functions of the ER to promote distinct steps of the viral life cycle from entry and replication to assembly and egress. The ER can act as the common denominator during infection for diverse virus families, thereby providing a shared principle that underlies the apparent complexity of relationships between viruses and host cells. As a plethora of information illuminating the molecular and cellular basis of virus–ER interactions has become available, these insights may lead to the development of crucial therapeutic agents.
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Affiliation(s)
- Madhu Sudhan Ravindran
- Department of Cell and Developmental Biology, University of Michigan Medical School, 109 Zina Pitcher Place, Room 3043, Ann Arbor, Michigan 48109, USA
| | - Parikshit Bagchi
- Department of Cell and Developmental Biology, University of Michigan Medical School, 109 Zina Pitcher Place, Room 3043, Ann Arbor, Michigan 48109, USA
| | - Corey Nathaniel Cunningham
- Department of Cell and Developmental Biology, University of Michigan Medical School, 109 Zina Pitcher Place, Room 3043, Ann Arbor, Michigan 48109, USA
| | - Billy Tsai
- Department of Cell and Developmental Biology, University of Michigan Medical School, 109 Zina Pitcher Place, Room 3043, Ann Arbor, Michigan 48109, USA
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170
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Shulla A, Randall G. (+) RNA virus replication compartments: a safe home for (most) viral replication. Curr Opin Microbiol 2016; 32:82-88. [PMID: 27253151 PMCID: PMC4983521 DOI: 10.1016/j.mib.2016.05.003] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Accepted: 05/03/2016] [Indexed: 12/19/2022]
Abstract
(+) RNA virus replication compartments form two structural classes. Both classes of replication compartments use cellular membrane curvature proteins. Both classes of replication compartments manipulate de novo lipid synthesis. Some double membrane vesicles use cellular lipid kinases and transfer proteins. Limited transient replication may occur before replication compartment formation.
This review describes recent advances in our understanding of the mechanisms by which (+) RNA viruses establish their replication niche.
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Affiliation(s)
- Ana Shulla
- Department of Microbiology, The University of Chicago, Chicago, IL 60637, United States
| | - Glenn Randall
- Department of Microbiology, The University of Chicago, Chicago, IL 60637, United States.
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171
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Dynamic lipid landscape of picornavirus replication organelles. Curr Opin Virol 2016; 19:1-6. [PMID: 27240115 DOI: 10.1016/j.coviro.2016.05.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Revised: 05/06/2016] [Accepted: 05/13/2016] [Indexed: 01/03/2023]
Abstract
Picornavirus infection induces rapid reorganization of the cellular membrane architecture and appearance of novel membranous structures associated with the viral RNA replication and virion assembly-replication organelles. Recent studies significantly advanced our understanding of their lipid composition and cellular mechanisms involved in their development. Picornaviruses activate synthesis of both structural and signaling lipids and reroute cellular cholesterol trafficking pathways to create unique membranous domains favoring viral replication. Rapidly replicating picornaviruses rely on posttranslational activation and/or specific recruitment of cellular proteins rather than on modulation of expression of cellular genes to create favorable membrane microenvironment. At the same time picornaviruses demonstrate remarkable adaptability to changes in the lipid landscape which should be taken into account when developing novel antiviral strategies.
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172
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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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173
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Wang H, Tai AW. Mechanisms of Cellular Membrane Reorganization to Support Hepatitis C Virus Replication. Viruses 2016; 8:v8050142. [PMID: 27213428 PMCID: PMC4885097 DOI: 10.3390/v8050142] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 04/20/2016] [Accepted: 05/15/2016] [Indexed: 12/13/2022] Open
Abstract
Like all positive-sense RNA viruses, hepatitis C virus (HCV) induces host membrane alterations for its replication termed the membranous web (MW). Assembling replication factors at a membranous structure might facilitate the processes necessary for genome replication and packaging and shield viral components from host innate immune defenses. The biogenesis of the HCV MW is a complex process involving a concerted effort of HCV nonstructural proteins with a growing list of host factors. Although a comprehensive understanding of MW formation is still missing, a number of important viral and host determinants have been identified. This review will summarize the recent studies that have led to our current knowledge of the role of viral and host factors in the biogenesis of the MWs and discuss how HCV uses this specialized membrane structure for its replication.
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Affiliation(s)
- Hongliang Wang
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
| | - Andrew W Tai
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
- Medicine Service, Ann Arbor Veterans Administration Health System, Ann Arbor, MI 48105, USA.
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Mutations in Encephalomyocarditis Virus 3A Protein Uncouple the Dependency of Genome Replication on Host Factors Phosphatidylinositol 4-Kinase IIIα and Oxysterol-Binding Protein. mSphere 2016; 1:mSphere00068-16. [PMID: 27303747 PMCID: PMC4888891 DOI: 10.1128/msphere.00068-16] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 04/25/2016] [Indexed: 12/18/2022] Open
Abstract
Positive-strand RNA viruses modulate lipid homeostasis to generate unique, membranous “replication organelles” (ROs) where viral genome replication takes place. Hepatitis C virus, encephalomyocarditis virus (EMCV), and enteroviruses have convergently evolved to hijack host phosphatidylinositol 4-kinases (PI4Ks), which produce PI4P lipids, to recruit oxysterol-binding protein (OSBP), a PI4P-binding protein that shuttles cholesterol to ROs. Consistent with the proposed coupling between PI4K and OSBP, enterovirus mutants resistant to PI4KB inhibitors are also resistant to OSBP inhibitors. Here, we show that EMCV can replicate without accumulating PI4P/cholesterol at ROs, by acquiring point mutations in nonstructural protein 3A. Remarkably, the mutations conferred resistance to PI4K but not OSBP inhibitors, thereby uncoupling the levels of dependency of EMCV RNA replication on PI4K and OSBP. This work may contribute to a deeper understanding of the roles of PI4K/PI4P and OSBP/cholesterol in membrane modifications induced by positive-strand RNA viruses. Positive-strand RNA [(+)RNA] viruses are true masters of reprogramming host lipid trafficking and synthesis to support virus genome replication. Via their membrane-associated 3A protein, picornaviruses of the genus Enterovirus (e.g., poliovirus, coxsackievirus, and rhinovirus) subvert Golgi complex-localized phosphatidylinositol 4-kinase IIIβ (PI4KB) to generate “replication organelles” (ROs) enriched in phosphatidylinositol 4-phosphate (PI4P). PI4P lipids serve to accumulate oxysterol-binding protein (OSBP), which subsequently transfers cholesterol to the ROs in a PI4P-dependent manner. Single-point mutations in 3A render enteroviruses resistant to both PI4KB and OSBP inhibition, indicating coupled dependency on these host factors. Recently, we showed that encephalomyocarditis virus (EMCV), a picornavirus that belongs to the Cardiovirus genus, also builds PI4P/cholesterol-enriched ROs. Like the hepatitis C virus (HCV) of the Flaviviridae family, it does so by hijacking the endoplasmic reticulum (ER)-localized phosphatidylinositol 4-kinase IIIα (PI4KA). Here we provide genetic evidence for the critical involvement of EMCV protein 3A in this process. Using a genetic screening approach, we selected EMCV mutants with single amino acid substitutions in 3A, which rescued RNA virus replication upon small interfering RNA (siRNA) knockdown or pharmacological inhibition of PI4KA. In the presence of PI4KA inhibitors, the mutants no longer induced PI4P, OSBP, or cholesterol accumulation at ROs, which aggregated into large cytoplasmic clusters. In contrast to the enterovirus escape mutants, we observed little if any cross-resistance of EMCV mutants to OSBP inhibitors, indicating an uncoupled level of dependency of their RNA replication on PI4KA and OSBP activities. This report may contribute to a better understanding of the roles of PI4KA and OSBP in membrane modifications induced by (+)RNA viruses. IMPORTANCE Positive-strand RNA viruses modulate lipid homeostasis to generate unique, membranous “replication organelles” (ROs) where viral genome replication takes place. Hepatitis C virus, encephalomyocarditis virus (EMCV), and enteroviruses have convergently evolved to hijack host phosphatidylinositol 4-kinases (PI4Ks), which produce PI4P lipids, to recruit oxysterol-binding protein (OSBP), a PI4P-binding protein that shuttles cholesterol to ROs. Consistent with the proposed coupling between PI4K and OSBP, enterovirus mutants resistant to PI4KB inhibitors are also resistant to OSBP inhibitors. Here, we show that EMCV can replicate without accumulating PI4P/cholesterol at ROs, by acquiring point mutations in nonstructural protein 3A. Remarkably, the mutations conferred resistance to PI4K but not OSBP inhibitors, thereby uncoupling the levels of dependency of EMCV RNA replication on PI4K and OSBP. This work may contribute to a deeper understanding of the roles of PI4K/PI4P and OSBP/cholesterol in membrane modifications induced by positive-strand RNA viruses.
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Vieyres G, Welsch K, Gerold G, Gentzsch J, Kahl S, Vondran FWR, Kaderali L, Pietschmann T. ABHD5/CGI-58, the Chanarin-Dorfman Syndrome Protein, Mobilises Lipid Stores for Hepatitis C Virus Production. PLoS Pathog 2016; 12:e1005568. [PMID: 27124600 PMCID: PMC4849665 DOI: 10.1371/journal.ppat.1005568] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 03/22/2016] [Indexed: 02/06/2023] Open
Abstract
Hepatitis C virus (HCV) particles closely mimic human very-low-density lipoproteins (VLDL) to evade humoral immunity and to facilitate cell entry. However, the principles that govern HCV association with VLDL components are poorly defined. Using an siRNA screen, we identified ABHD5 (α/β hydrolase domain containing protein 5, also known as CGI-58) as a new host factor promoting both virus assembly and release. ABHD5 associated with lipid droplets and triggered their hydrolysis. Importantly, ABHD5 Chanarin-Dorfman syndrome mutants responsible for a rare lipid storage disorder in humans were mislocalised, and unable to consume lipid droplets or support HCV production. Additional ABHD5 mutagenesis revealed a novel tribasic motif that does not influence subcellular localization but determines both ABHD5 lipolytic and proviral properties. These results indicate that HCV taps into the lipid droplet triglyceride reservoir usurping ABHD5 lipase cofactor function. They also suggest that the resulting lipid flux, normally devoted to VLDL synthesis, also participates in the assembly and release of the HCV lipo-viro-particle. Altogether, our study provides the first association between the Chanarin-Dorfman syndrome protein and an infectious disease and sheds light on the hepatic manifestations of this rare genetic disorder as well as on HCV morphogenesis. HCV replication is linked to the host lipid metabolism, and virions are secreted as lipo-viro-particles whose density, size and biochemical content resemble VLDL. HCV assembles close to lipid droplets and is released via the secretory pathway, but it remains unclear how it accesses the VLDL assembly pathway. In this study, we identified ABHD5 as a new host factor supporting HCV assembly and release. ABHD5 is a lipid droplet-associated lipase cofactor. In hepatocytes, ABHD5 was proposed to promote the recruitment of triglycerides from cytosolic towards luminal lipid droplets by mediating a cycle of phospholipid hydrolysis/re-esterification. Our data suggest that this ABHD5-dependent lipid transfer is not only required for VLDL maturation, but also for HCV assembly and virion release, indicating that lipid remodelling impacts on both assembly and virus transport. Finally, ABHD5 is associated with the Chanarin-Dorfman syndrome, a rare human genetic lipid metabolism disorder. We found that the Chanarin-Dorfman syndrome mutants were unable to support HCV assembly, pointing at a new host polymorphism that could determine susceptibility to HCV infection. Altogether, our results establish a new link between HCV, VLDL assembly and lipid remodeling pathways and open new possibilities to study the etiology of the liver manifestations of the Chanarin-Dorfman syndrome.
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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), Hannover, Germany
| | - Kathrin Welsch
- 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), Hannover, Germany
| | - Gisa Gerold
- 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), Hannover, Germany
| | - Juliane Gentzsch
- 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), Hannover, Germany
| | - Sina Kahl
- 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), Hannover, Germany
| | - Florian W. R. Vondran
- German Centre for Infection Research (DZIF), partner site Hannover-Braunschweig, Braunschweig, Germany
- ReMediES, Department of General, Visceral and Transplant Surgery, Hannover Medical School, Hannover, Germany
| | - Lars Kaderali
- Institute for Bioinformatics, University Medicine Greifswald, Greifswald, 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), Hannover, Germany
- German Centre for Infection Research (DZIF), partner site Hannover-Braunschweig, Braunschweig, Germany
- * E-mail:
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van der Hoeven B, Oudshoorn D, Koster AJ, Snijder EJ, Kikkert M, Bárcena M. Biogenesis and architecture of arterivirus replication organelles. Virus Res 2016; 220:70-90. [PMID: 27071852 PMCID: PMC7111217 DOI: 10.1016/j.virusres.2016.04.001] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Accepted: 04/01/2016] [Indexed: 02/06/2023]
Abstract
Arterivirus RNA synthesis presumably is associated with double-membrane vesicles (DMVs). Putative intermediates in DMV formation were detected in infected cells. Arterivirus-induced DMVs form a highly interconnected reticulovesicular network (RVN). Expression of the nsp2-3 replicase polyprotein fragment induces a comparable RVN. Nsp2-7 expression results in smaller DMVs, closer in size to DMVs found in infection.
All eukaryotic positive-stranded RNA (+RNA) viruses appropriate host cell membranes and transform them into replication organelles, specialized micro-environments that are thought to support viral RNA synthesis. Arteriviruses (order Nidovirales) belong to the subset of +RNA viruses that induce double-membrane vesicles (DMVs), similar to the structures induced by e.g. coronaviruses, picornaviruses and hepatitis C virus. In the last years, electron tomography has revealed substantial differences between the structures induced by these different virus groups. Arterivirus-induced DMVs appear to be closed compartments that are continuous with endoplasmic reticulum membranes, thus forming an extensive reticulovesicular network (RVN) of intriguing complexity. This RVN is remarkably similar to that described for the distantly related coronaviruses (also order Nidovirales) and sets them apart from other DMV-inducing viruses analysed to date. We review here the current knowledge and open questions on arterivirus replication organelles and discuss them in the light of the latest studies on other DMV-inducing viruses, particularly coronaviruses. Using the equine arteritis virus (EAV) model system and electron tomography, we present new data regarding the biogenesis of arterivirus-induced DMVs and uncover numerous putative intermediates in DMV formation. We generated cell lines that can be induced to express specific EAV replicase proteins and showed that DMVs induced by the transmembrane proteins nsp2 and nsp3 form an RVN and are comparable in topology and architecture to those formed during viral infection. Co-expression of the third EAV transmembrane protein (nsp5), expressed as part of a self-cleaving polypeptide that mimics viral polyprotein processing in infected cells, led to the formation of DMVs whose size was more homogenous and closer to what is observed upon EAV infection, suggesting a regulatory role for nsp5 in modulating membrane curvature and DMV formation.
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Affiliation(s)
- Barbara van der Hoeven
- Electron Microscopy Section, Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Diede Oudshoorn
- Molecular Virology Laboratory, Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Abraham J Koster
- Electron Microscopy Section, Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Eric J Snijder
- Molecular Virology Laboratory, Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Marjolein Kikkert
- Molecular Virology Laboratory, Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands.
| | - Montserrat Bárcena
- Electron Microscopy Section, Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands.
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177
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Fernández de Castro I, Fernández JJ, Barajas D, Nagy PD, Risco C. Three-dimensional imaging of the intracellular assembly of a functional viral RNA replicase complex. J Cell Sci 2016; 130:260-268. [PMID: 27026525 DOI: 10.1242/jcs.181586] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 03/18/2016] [Indexed: 01/30/2023] Open
Abstract
Positive-strand RNA viruses, which can be devastating pathogens in humans, animals and plants, replicate their genomes on intracellular membranes. Here, we describe the three-dimensional ultrastructural organization of a tombusvirus replicase in yeast, a valuable model for exploring virus-host interactions. We visualized the intracellular distribution of a viral replicase protein using metal-tagging transmission electron microscopy, a highly sensitive nanotechnology whose full potential remains to be developed. These three-dimensional images show how viral replicase molecules are organized when they are incorporated into the active domains of the intracellular replication compartment. Our approach provides a means to study protein activation mechanisms in cells and to identify targets for new antiviral compounds.
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Affiliation(s)
- Isabel Fernández de Castro
- Cell Structure Laboratory, Centro Nacional de Biotecnología (CNB-CSIC), Campus de Cantoblanco, Madrid 28049, Spain
| | - José J Fernández
- Department of Structure of Macromolecules, Centro Nacional de Biotecnología (CNB-CSIC), Campus de Cantoblanco, Madrid 28049, Spain
| | - Daniel Barajas
- Department of Plant Pathology, University of Kentucky, Lexington, Kentucky, KY 40546, USA
| | - Peter D Nagy
- Department of Plant Pathology, University of Kentucky, Lexington, Kentucky, KY 40546, USA
| | - Cristina Risco
- Cell Structure Laboratory, Centro Nacional de Biotecnología (CNB-CSIC), Campus de Cantoblanco, Madrid 28049, Spain
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178
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Hepatitis C virus NS5A protein cooperates with phosphatidylinositol 4-kinase IIIα to induce mitochondrial fragmentation. Sci Rep 2016; 6:23464. [PMID: 27010100 PMCID: PMC4806301 DOI: 10.1038/srep23464] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Accepted: 03/07/2016] [Indexed: 12/22/2022] Open
Abstract
Hepatitis C virus (HCV) has long been observed to take advantage of the host mitochondria to support viral replication and assembly. The HCV core protein has been implicated to fragment host mitochondria. In this report, we have discovered that the non-structural protein 5A (NS5A) plays an instructive role in attaching ER with mitochondria, causing mitochondrial fragmentation. Dynamin-related protein 1(Drp1), a host protein essential to mitochondrial membrane fission, does not play a role in NS5A-induced mitochondrial fragmentation. Instead, phosphatidylinositol 4-kinase IIIα (PI4KA), which has been demonstrated to bind to NS5A and is required to support HCV life cycle, is required for NS5A to induce mitochondrial fragmentation. Both NS5A and core are required by HCV to fragment the mitochondria, as inhibiting either of their respective downstream proteins, PI4KA or Drp1, resulted in lengthening of mitochondria tubules in HCVcc-infected cells. By fragmenting the mitochondria, NS5A renders the cells more resistant to mitochondria mediated apoptosis. This finding indicates previously-ignored contribution of NS5A in HCV-induced mitochondria dysfunction.
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179
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Fat(al) attraction: Picornaviruses Usurp Lipid Transfer at Membrane Contact Sites to Create Replication Organelles. Trends Microbiol 2016; 24:535-546. [PMID: 27020598 PMCID: PMC7126954 DOI: 10.1016/j.tim.2016.02.017] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Revised: 02/23/2016] [Accepted: 02/25/2016] [Indexed: 12/23/2022]
Abstract
All viruses that carry a positive-sense RNA genome (+RNA), such as picornaviruses, hepatitis C virus, dengue virus, and SARS- and MERS-coronavirus, confiscate intracellular membranes of the host cell to generate new compartments (i.e., replication organelles) for amplification of their genome. Replication organelles (ROs) are membranous structures that not only harbor viral proteins but also contain a specific array of hijacked host factors that create a unique lipid microenvironment optimal for genome replication. While some lipids may be locally synthesized de novo, other lipids are shuttled towards ROs. In picornavirus-infected cells, lipids are exchanged at membrane contact sites between ROs and other organelles. In this paper, we review recent advances in our understanding of how picornaviruses exploit host membrane contact site machinery to generate ROs, a mechanism that is used by some other +RNA viruses as well. Picornaviruses create replication organelles with a unique protein and lipid composition to amplify their genome. Picornaviruses hijack membrane contact site machinery to shuttle lipids to their replication organelles. Picornaviruses from different genera employ a cholesterol/PI4P counterflux mechanism to accumulate cholesterol at replication organelles.
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180
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HCV RNA traffic and association with NS5A in living cells. Virology 2016; 493:60-74. [PMID: 26999027 DOI: 10.1016/j.virol.2016.02.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Revised: 02/11/2016] [Accepted: 02/18/2016] [Indexed: 01/05/2023]
Abstract
The spatiotemporal dynamics of Hepatitis C Virus (HCV) RNA localisation are poorly understood. To address this we engineered HCV genomes harbouring MS2 bacteriophage RNA stem-loops within the 3'-untranslated region to allow tracking of HCV RNA via specific interaction with a MS2-Coat-mCherry fusion protein. Despite the impact of these insertions on viral fitness, live imaging revealed that replication of tagged-HCV genomes induced specific redistribution of the mCherry-tagged-MS2-Coat protein to motile and static foci. Further analysis showed that HCV RNA was associated with NS5A in both static and motile structures while a subset of motile NS5A structures was devoid of HCV RNA. Further investigation of viral RNA traffic with respect to lipid droplets (LDs) revealed HCV RNA-positive structures in close association with LDs. These studies provide new insights into the dynamics of HCV RNA traffic with NS5A and LDs and provide a platform for future investigations of HCV replication and assembly.
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181
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Fernández de Castro I, Tenorio R, Risco C. Virus assembly factories in a lipid world. Curr Opin Virol 2016; 18:20-6. [PMID: 26985879 DOI: 10.1016/j.coviro.2016.02.009] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 02/11/2016] [Accepted: 02/19/2016] [Indexed: 12/15/2022]
Abstract
Many viruses build specialized structures known as viral factories, a protected environment in which viral genome replication and morphogenesis take place. Recent findings show that viruses manipulate lipid flows to assemble these replication platforms. Viruses are thus able to create new membranes by interfering with lipid metabolism, targeting and transport; they make use of specific lipid transfer proteins (LTP) at membrane contact sites, and frequently recruit endoplasmic reticulum (ER), ER export sites, and mitochondria. Some factories, such as those built by plant and certain animal viruses, are motile membranous structures involved in intracellular or intercellular transport of the replicated viral genome. The identification of lipids and LTP subverted by viruses might lead to better understand and fight viral infections.
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Affiliation(s)
- Isabel Fernández de Castro
- Cell Structure Laboratory, Centro Nacional de Biotecnología, CNB-CSIC, UAM, Campus de Cantoblanco, 28049 Madrid, Spain.
| | - Raquel Tenorio
- Cell Structure Laboratory, Centro Nacional de Biotecnología, CNB-CSIC, UAM, Campus de Cantoblanco, 28049 Madrid, Spain
| | - Cristina Risco
- Cell Structure Laboratory, Centro Nacional de Biotecnología, CNB-CSIC, UAM, Campus de Cantoblanco, 28049 Madrid, Spain.
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182
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Helms JB, Kaloyanova DV, Strating JRP, van Hellemond JJ, van der Schaar HM, Tielens AGM, van Kuppeveld FJM, Brouwers JF. Targeting of the hydrophobic metabolome by pathogens. Traffic 2016; 16:439-60. [PMID: 25754025 PMCID: PMC7169838 DOI: 10.1111/tra.12280] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Revised: 01/09/2015] [Accepted: 01/09/2015] [Indexed: 12/12/2022]
Abstract
The hydrophobic molecules of the metabolome – also named the lipidome – constitute a major part of the entire metabolome. Novel technologies show the existence of a staggering number of individual lipid species, the biological functions of which are, with the exception of only a few lipid species, unknown. Much can be learned from pathogens that have evolved to take advantage of the complexity of the lipidome to escape the immune system of the host organism and to allow their survival and replication. Different types of pathogens target different lipids as shown in interaction maps, allowing visualization of differences between different types of pathogens. Bacterial and viral pathogens target predominantly structural and signaling lipids to alter the cellular phenotype of the host cell. Fungal and parasitic pathogens have complex lipidomes themselves and target predominantly the release of polyunsaturated fatty acids from the host cell lipidome, resulting in the generation of eicosanoids by either the host cell or the pathogen. Thus, whereas viruses and bacteria induce predominantly alterations in lipid metabolites at the host cell level, eukaryotic pathogens focus on interference with lipid metabolites affecting systemic inflammatory reactions that are part of the immune system. A better understanding of the interplay between host–pathogen interactions will not only help elucidate the fundamental role of lipid species in cellular physiology, but will also aid in the generation of novel therapeutic drugs.
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Affiliation(s)
- J Bernd Helms
- Department of Biochemistry and Cell Biology, Faculty of Veterinary Medicine & Institute of Biomembranes, Utrecht University, Yalelaan 2, 3584 CM, Utrecht, The Netherlands
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183
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Grassi G, Di Caprio G, Fimia GM, Ippolito G, Tripodi M, Alonzi T. Hepatitis C virus relies on lipoproteins for its life cycle. World J Gastroenterol 2016; 22:1953-1965. [PMID: 26877603 PMCID: PMC4726671 DOI: 10.3748/wjg.v22.i6.1953] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Revised: 10/19/2015] [Accepted: 12/21/2015] [Indexed: 02/06/2023] Open
Abstract
Hepatitis C virus (HCV) infects over 150 million people worldwide. In most cases, HCV infection becomes chronic causing liver disease ranging from fibrosis to cirrhosis and hepatocellular carcinoma. Viral persistence and pathogenesis are due to the ability of HCV to deregulate specific host processes, mainly lipid metabolism and innate immunity. In particular, HCV exploits the lipoprotein machineries for almost all steps of its life cycle. The aim of this review is to summarize current knowledge concerning the interplay between HCV and lipoprotein metabolism. We discuss the role played by members of lipoproteins in HCV entry, replication and virion production.
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184
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Malkovskiy AV, Wagh DA, Longo FM, Rajadas J. A strategy for analyzing bond strength and interaction kinetics between Pleckstrin homology domains and PI(4,5)P2 phospholipids using force distance spectroscopy and surface plasmon resonance. Analyst 2016; 140:4558-65. [PMID: 26040325 DOI: 10.1039/c5an00498e] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Phospholipids are important membrane components involved in diverse biological activities ranging from cell signaling to infection by viral particles. A thorough understanding of protein-phospholipid interaction dynamics is thus crucial for deciphering basic cellular processes as well as for targeted drug discovery. For any specific phospholipid-protein binding experiment, various groups have reported different binding constants, which are strongly dependent on applied conditions of interactions. Here, we report a method for accurate determination of the binding affinity and specificity between proteins and phospholipids using a model interaction between PLC-δ1/PH and phosphoinositide phospholipid PtdIns(4,5)P2. We developed an accurate Force Distance Spectroscopy (FDS)-based assay and have attempted to resolve the problem of variation in the observed binding constant by directly measuring the bond force. We confirm the FDS findings of a high bond strength of ∼0.19 ± 0.04 nN by Surface Plasmon Resonance (SPR) data analysis, segregating non-specific interactions, which show a significantly lower K(D) suggesting tight binding.
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Affiliation(s)
- A V Malkovskiy
- Stanford BioADD Laboratory, Stanford, California 94305, USA.
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185
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Eyre NS, Hampton-Smith RJ, Aloia AL, Eddes JS, Simpson KJ, Hoffmann P, Beard MR. Phosphorylation of NS5A Serine-235 is essential to hepatitis C virus RNA replication and normal replication compartment formation. Virology 2016; 491:27-44. [PMID: 26874015 DOI: 10.1016/j.virol.2016.01.018] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Revised: 01/21/2016] [Accepted: 01/23/2016] [Indexed: 01/09/2023]
Abstract
Hepatitis C virus (HCV) NS5A protein is essential for HCV RNA replication and virus assembly. Here we report the identification of NS5A phosphorylation sites Ser-222, Ser-235 and Thr-348 during an infectious HCV replication cycle and demonstrate that Ser-235 phosphorylation is essential for HCV RNA replication. Confocal microscopy revealed that both phosphoablatant (S235A) and phosphomimetic (S235D) mutants redistribute NS5A to large juxta-nuclear foci that display altered colocalization with known replication complex components. Using electron microscopy (EM) we found that S235D alters virus-induced membrane rearrangements while EM using 'APEX2'-tagged viruses demonstrated S235D-mediated enrichment of NS5A in irregular membranous foci. Finally, using a customized siRNA screen of candidate NS5A kinases and subsequent analysis using a phospho-specific antibody, we show that phosphatidylinositol-4 kinase III alpha (PI4KIIIα) is important for Ser-235 phosphorylation. We conclude that Ser-235 phosphorylation of NS5A is essential for HCV RNA replication and normal replication complex formation and is regulated by PI4KIIIα.
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Affiliation(s)
- Nicholas S Eyre
- School of Biological Sciences and Research Centre for Infectious Diseases, University of Adelaide, Adelaide, Australia; Centre for Cancer Biology, SA Pathology, Adelaide, Australia.
| | - Rachel J Hampton-Smith
- School of Biological Sciences and Research Centre for Infectious Diseases, University of Adelaide, Adelaide, Australia; Centre for Cancer Biology, SA Pathology, Adelaide, Australia
| | - Amanda L Aloia
- School of Biological Sciences and Research Centre for Infectious Diseases, University of Adelaide, Adelaide, Australia; Centre for Cancer Biology, SA Pathology, Adelaide, Australia
| | - James S Eddes
- Adelaide Proteomics Centre, School of Biological Sciences, University of Adelaide, Adelaide, Australia
| | - Kaylene J Simpson
- Victorian Centre for Functional Genomics, Peter MacCallum Cancer Centre, East Melbourne, Australia; The Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Australia
| | - Peter Hoffmann
- Adelaide Proteomics Centre, School of Biological Sciences, University of Adelaide, Adelaide, Australia; Institute for Photonics and Advanced Sensing (IPAS), University of Adelaide, Adelaide, Australia
| | - Michael R Beard
- School of Biological Sciences and Research Centre for Infectious Diseases, University of Adelaide, Adelaide, Australia; Centre for Cancer Biology, SA Pathology, Adelaide, Australia
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186
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Type III phosphatidylinositol 4 kinases: structure, function, regulation, signalling and involvement in disease. Biochem Soc Trans 2016; 44:260-6. [DOI: 10.1042/bst20150219] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Many important cellular functions are regulated by the selective recruitment of proteins to intracellular membranes mediated by specific interactions with lipid phosphoinositides. The enzymes that generate lipid phosphoinositides therefore must be properly positioned and regulated at their correct cellular locations. Phosphatidylinositol 4 kinases (PI4Ks) are key lipid signalling enzymes, and they generate the lipid species phosphatidylinositol 4-phosphate (PI4P), which plays important roles in regulating physiological processes including membrane trafficking, cytokinesis and organelle identity. PI4P also acts as the substrate for the generation of the signalling phosphoinositides phosphatidylinositol 4,5-bisphosphate (PIP2) and phosphatidylinositol 3,4,5-trisphosphate (PIP3). PI4Ks also play critical roles in a number of pathological processes including mediating replication of a number of pathogenic RNA viruses, and in the development of the parasite responsible for malaria. Key to the regulation of PI4Ks is their regulation by a variety of both host and viral protein-binding partners. We review herein our current understanding of the structure, regulatory interactions and role in disease of the type III PI4Ks.
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187
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Positive-strand RNA viruses stimulate host phosphatidylcholine synthesis at viral replication sites. Proc Natl Acad Sci U S A 2016; 113:E1064-73. [PMID: 26858414 DOI: 10.1073/pnas.1519730113] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
All positive-strand RNA viruses reorganize host intracellular membranes to assemble their viral replication complexes (VRCs); however, how these viruses modulate host lipid metabolism to accommodate such membrane proliferation and rearrangements is not well defined. We show that a significantly increased phosphatidylcholine (PC) content is associated with brome mosaic virus (BMV) replication in both natural host barley and alternate host yeast based on a lipidomic analysis. Enhanced PC levels are primarily associated with the perinuclear ER membrane, where BMV replication takes place. More specifically, BMV replication protein 1a interacts with and recruits Cho2p (choline requiring 2), a host enzyme involved in PC synthesis, to the site of viral replication. These results suggest that PC synthesized at the site of VRC assembly, not the transport of existing PC, is responsible for the enhanced accumulation. Blocking PC synthesis by deleting the CHO2 gene resulted in VRCs with wider diameters than those in wild-type cells; however, BMV replication was significantly inhibited, highlighting the critical role of PC in VRC formation and viral replication. We further show that enhanced PC levels also accumulate at the replication sites of hepatitis C virus and poliovirus, revealing a conserved feature among a group of positive-strand RNA viruses. Our work also highlights a potential broad-spectrum antiviral strategy that would disrupt PC synthesis at the sites of viral replication but would not alter cellular processes.
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188
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Yin P, Hong Z, Yang X, Chung RT, Zhang L. A role for retromer in hepatitis C virus replication. Cell Mol Life Sci 2016; 73:869-81. [PMID: 26298293 PMCID: PMC11108358 DOI: 10.1007/s00018-015-2027-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Revised: 08/13/2015] [Accepted: 08/18/2015] [Indexed: 12/20/2022]
Abstract
Hepatitis C virus (HCV) has infected over 170 million people worldwide. Phosphatidylinositol 4-phosphate (PI4P) is the organelle-specific phosphoinositide enriched at sites of HCV replication. Whether retromer, a PI4P-related host transport machinery, unloads its cargo at HCV replication sites remains inconclusive. We sought to characterize the role of retromer in HCV replication. Here, we demonstrated the interaction between retromer subunit Vps35 and HCV NS5A protein by immunoprecipitation and GST pulldown. Vps35 colocalized with NS5A and PI4P in both OR6 replicon and JFH1 infected Huh 7.5.1 cells. HCV replication was inhibited upon silencing retromer subunits. CIMPR, a typical retromer cargo, participated in HCV replication. Our data suggest that retromer component Vps35 is recruited by NS5A to viral replication sites where PI4P unloads CIMPR. These findings demonstrate a dependence role of retromer in HCV replication and identify retromer as a potential therapeutic target against HCV.
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Affiliation(s)
- Peiqi Yin
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100176, China
| | - Zhi Hong
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100176, China
| | - Xiaojie Yang
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100176, China
| | - Raymond T Chung
- Gastrointestinal Division, Department of Medicine, Liver Center, Massachusetts General Hospital, Harvard Medical School, Boston, MA, 02114, USA
| | - Leiliang Zhang
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100176, China.
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189
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Kovalev N, de Castro Martín IF, Pogany J, Barajas D, Pathak K, Risco C, Nagy PD. Role of Viral RNA and Co-opted Cellular ESCRT-I and ESCRT-III Factors in Formation of Tombusvirus Spherules Harboring the Tombusvirus Replicase. J Virol 2016; 90:3611-26. [PMID: 26792735 PMCID: PMC4794697 DOI: 10.1128/jvi.02775-15] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Accepted: 01/12/2016] [Indexed: 12/21/2022] Open
Abstract
UNLABELLED Plus-stranded RNA viruses induce membrane deformations in infected cells in order to build viral replication complexes (VRCs). Tomato bushy stunt virus (TBSV) co-opts cellular ESCRT (endosomal sorting complexes required for transport) proteins to induce the formation of vesicle (spherule)-like structures in the peroxisomal membrane with tight openings toward the cytosol. In this study, using a yeast (Saccharomyces cerevisiae) vps23Δ bro1Δ double-deletion mutant, we showed that the Vps23p ESCRT-I protein (Tsg101 in mammals) and Bro1p (ALIX) ESCRT-associated protein, both of which bind to the viral p33 replication protein, play partially complementary roles in TBSV replication in cells and in cell extracts. Dual expression of dominant-negative versions of Arabidopsis homologs of Vps23p and Bro1p inhibited tombusvirus replication to greater extent than individual expression in Nicotiana benthamiana leaves. We also demonstrated the critical role of Snf7p (CHMP4), Vps20p, and Vps24p ESCRT-III proteins in tombusvirus replication in yeast and in vitro. Electron microscopic imaging of vps23Δ yeast revealed the lack of tombusvirus-induced spherule-like structures, while crescent-like structures are formed in ESCRT-III deletion yeasts replicating TBSV RNA. In addition, we also showed that the length of the viral RNA affects the sizes of spherules formed in N. benthamiana cells. The 4.8-kb genomic RNA is needed for the formation of spherules 66 nm in diameter, while spherules formed during the replication of the ∼600-nucleotide (nt)-long defective interfering RNA in the presence of p33 and p92 replication proteins are 42 nm. We propose that the viral RNA serves as a "measuring string" during VRC assembly and spherule formation. IMPORTANCE Plant positive-strand RNA viruses, similarly to animal positive-strand RNA viruses, replicate in membrane-bound viral replicase complexes in the cytoplasm of infected cells. Identification of cellular and viral factors affecting the formation of the membrane-bound viral replication complex is a major frontier in current virology research. In this study, we dissected the functions of co-opted cellular ESCRT-I (endosomal sorting complexes required for transport I) and ESCRT-III proteins and the viral RNA in tombusvirus replicase complex formation using in vitro, yeast-based, and plant-based approaches. Electron microscopic imaging revealed the lack of tombusvirus-induced spherule-like structures in ESCRT-I or ESCRT-III deletion yeasts replicating TBSV RNA, demonstrating the requirement for these co-opted cellular factors in tombusvirus replicase formation. The work could be of broad interest in virology and beyond.
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Affiliation(s)
- Nikolay Kovalev
- Department of Plant Pathology, University of Kentucky, Lexington, Kentucky, USA
| | | | - Judit Pogany
- Department of Plant Pathology, University of Kentucky, Lexington, Kentucky, USA
| | - Daniel Barajas
- Department of Plant Pathology, University of Kentucky, Lexington, Kentucky, USA
| | - Kunj Pathak
- Department of Plant Pathology, University of Kentucky, Lexington, Kentucky, USA
| | - Cristina Risco
- Cell Structure Laboratory, Centro Nacional de Biotecnología, Madrid, Spain
| | - Peter D Nagy
- Department of Plant Pathology, University of Kentucky, Lexington, Kentucky, USA
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190
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Bertino G, Ardiri A, Proiti M, Rigano G, Frazzetto E, Demma S, Ruggeri MI, Scuderi L, Malaguarnera G, Bertino N, Rapisarda V, Di Carlo I, Toro A, Salomone F, Malaguarnera M, Bertino E, Malaguarnera M. Chronic hepatitis C: This and the new era of treatment. World J Hepatol 2016; 8:92-106. [PMID: 26807205 PMCID: PMC4716531 DOI: 10.4254/wjh.v8.i2.92] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Revised: 09/29/2015] [Accepted: 12/18/2015] [Indexed: 02/06/2023] Open
Abstract
Over the last years it has started a real revolution in the treatment of chronic hepatitis C. This occurred for the availability of direct-acting antiviral agents that allow to reach sustained virologic response in approximately 90% of cases. In the near future further progress will be achieved with the use of pan-genotypic drugs with high efficacy but without side effects.
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191
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Prolactin Regulatory Element Binding Protein Is Involved in Hepatitis C Virus Replication by Interaction with NS4B. J Virol 2016; 90:3093-111. [PMID: 26739056 DOI: 10.1128/jvi.01540-15] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 12/30/2015] [Indexed: 12/12/2022] Open
Abstract
UNLABELLED It has been proposed that the hepatitis C virus (HCV) NS4B protein triggers the membranous HCV replication compartment, but the underlying molecular mechanism is not fully understood. Here, we screened for NS4B-associated membrane proteins by tandem affinity purification and proteome analysis and identified 202 host proteins. Subsequent screening of replicon cells with small interfering RNA identified prolactin regulatory element binding (PREB) to be a novel HCV host cofactor. The interaction between PREB and NS4B was confirmed by immunoprecipitation, immunofluorescence, and proximity ligation assays. PREB colocalized with double-stranded RNA and the newly synthesized HCV RNA labeled with bromouridine triphosphate in HCV replicon cells. Furthermore, PREB shifted to detergent-resistant membranes (DRMs), where HCV replication complexes reside, in the presence of NS4B expression in Huh7 cells. However, a PREB mutant lacking the NS4B-binding region (PREBd3) could not colocalize with double-stranded RNA and did not shift to the DRM in the presence of NS4B. These results indicate that PREB locates at the HCV replication complex by interacting with NS4B. PREB silencing inhibited the formation of the membranous HCV replication compartment and increased the protease and nuclease sensitivity of HCV replicase proteins and RNA in DRMs, respectively. Collectively, these data indicate that PREB promotes HCV RNA replication by participating in the formation of the membranous replication compartment and by maintaining its proper structure by interacting with NS4B. Furthermore, PREB was induced by HCV infection in vitro and in vivo. Our findings provide new insights into HCV host cofactors. IMPORTANCE The hepatitis C virus (HCV) protein NS4B can induce alteration of the endoplasmic reticulum and the formation of a membranous web structure, which provides a platform for the HCV replication complex. The molecular mechanism by which NS4B induces the membranous HCV replication compartment is not understood. We screened for NS4B-associated membrane proteins by tandem affinity purification and proteome analysis, followed by screening with small interfering RNA. We identified prolactin regulatory element binding (PREB) to be a novel HCV host cofactor. PREB is induced by HCV infection and recruited into the replication complex by interaction with NS4B. Recruited PREB promotes HCV RNA replication by participating in the formation of the membranous HCV replication compartment. To our knowledge, the effect of NS4B-binding protein on the formation of the membranous HCV replication compartment is newly described in this report. Our findings are expected to provide new insights into HCV host cofactors.
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192
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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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193
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Perin PM, Haid S, Brown RJ, Doerrbecker J, Schulze K, Zeilinger C, von Schaewen M, Heller B, Vercauteren K, Luxenburger E, Baktash YM, Vondran FW, Speerstra S, Awadh A, Mukhtarov F, Schang LM, Kirschning A, Müller R, Guzman CA, Kaderali L, Randall G, Meuleman P, Ploss A, Pietschmann T. Flunarizine prevents hepatitis C virus membrane fusion in a genotype-dependent manner by targeting the potential fusion peptide within E1. Hepatology 2016; 63:49-62. [PMID: 26248546 PMCID: PMC4688136 DOI: 10.1002/hep.28111] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 08/05/2015] [Indexed: 12/12/2022]
Abstract
UNLABELLED To explore mechanisms of hepatitis C viral (HCV) replication we screened a compound library including licensed drugs. Flunarizine, a diphenylmethylpiperazine used to treat migraine, inhibited HCV cell entry in vitro and in vivo in a genotype-dependent fashion. Analysis of mosaic viruses between susceptible and resistant strains revealed that E1 and E2 glycoproteins confer susceptibility to flunarizine. Time of addition experiments and single particle tracking of HCV demonstrated that flunarizine specifically prevents membrane fusion. Related phenothiazines and pimozide also inhibited HCV infection and preferentially targeted HCV genotype 2 viruses. However, phenothiazines and pimozide exhibited improved genotype coverage including the difficult to treat genotype 3. Flunarizine-resistant HCV carried mutations within the alleged fusion peptide and displayed cross-resistance to these compounds, indicating that these drugs have a common mode of action. CONCLUSION These observations reveal novel details about HCV membrane fusion; moreover, flunarizine and related compounds represent first-in-class HCV fusion inhibitors that merit consideration for repurposing as a cost-effective component of HCV combination therapies.
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Affiliation(s)
- Paula M. Perin
- Institute of Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research; a joint venture between the Medical School Hannover and the Helmholtz Centre for Infection ResearchHannoverGermany
| | - Sibylle Haid
- Institute of Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research; a joint venture between the Medical School Hannover and the Helmholtz Centre for Infection ResearchHannoverGermany
| | - Richard J.P. Brown
- Institute of Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research; a joint venture between the Medical School Hannover and the Helmholtz Centre for Infection ResearchHannoverGermany
| | - Juliane Doerrbecker
- Institute of Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research; a joint venture between the Medical School Hannover and the Helmholtz Centre for Infection ResearchHannoverGermany
| | - Kai Schulze
- Department of Vaccinology and Applied MicrobiologyHelmholtz Centre of Infection ResearchBraunschweigGermany
| | - Carsten Zeilinger
- Institute of Organic Chemistry and Center of Biomolecular Drug Research, Leibniz UniversitätHannoverGermany
| | | | - Brigitte Heller
- Department of Molecular BiologyPrinceton UniversityPrincetonNJ
| | | | - Eva Luxenburger
- Helmholtz Institute for Pharmaceutical Research SaarlandSaarbrückenGermany
| | | | - Florian W.R. Vondran
- ReMediES, Department of GeneralVisceral and Transplantation Surgery, Hannover Medical SchoolHannoverGermany,German Centre for Infection Research, Hannover‐BraunschweigGermany
| | - Sietkse Speerstra
- Department of BiochemistryUniversity of AlbertaEdmontonABCanada,Li Ka Shing Institute of Virology, University of AlbertaEdmontonABCanada
| | - Abdullah Awadh
- Li Ka Shing Institute of Virology, University of AlbertaEdmontonABCanada,Department of Medical Microbiology and ImmunologyUniversity of AlbertaEdmontonABCanada
| | - Furkat Mukhtarov
- Department of BiochemistryUniversity of AlbertaEdmontonABCanada,Li Ka Shing Institute of Virology, University of AlbertaEdmontonABCanada
| | - Luis M. Schang
- Department of BiochemistryUniversity of AlbertaEdmontonABCanada,Li Ka Shing Institute of Virology, University of AlbertaEdmontonABCanada,Department of Medical Microbiology and ImmunologyUniversity of AlbertaEdmontonABCanada
| | - Andreas Kirschning
- Institute of Organic Chemistry and Center of Biomolecular Drug Research, Leibniz UniversitätHannoverGermany
| | - Rolf Müller
- Helmholtz Institute for Pharmaceutical Research SaarlandSaarbrückenGermany
| | - Carlos A. Guzman
- Department of Vaccinology and Applied MicrobiologyHelmholtz Centre of Infection ResearchBraunschweigGermany
| | | | - Glenn Randall
- Department of MicrobiologyThe University of ChicagoChicagoIL
| | | | - Alexander Ploss
- Department of Molecular BiologyPrinceton UniversityPrincetonNJ
| | - Thomas Pietschmann
- Institute of Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research; a joint venture between the Medical School Hannover and the Helmholtz Centre for Infection ResearchHannoverGermany,German Centre for Infection Research, Hannover‐BraunschweigGermany
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194
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Fauvelle C, Felmlee DJ, Crouchet E, Lee J, Heydmann L, Lefèvre M, Magri A, Hiet MS, Fofana I, Habersetzer F, Foung SKH, Milne R, Patel AH, Vercauteren K, Meuleman P, Zeisel MB, Bartenschlager R, Schuster C, Baumert TF. Apolipoprotein E Mediates Evasion From Hepatitis C Virus Neutralizing Antibodies. Gastroenterology 2016; 150:206-217.e4. [PMID: 26404951 DOI: 10.1053/j.gastro.2015.09.014] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Revised: 08/06/2015] [Accepted: 09/11/2015] [Indexed: 12/15/2022]
Abstract
BACKGROUND & AIMS Efforts to develop an effective vaccine against hepatitis C virus (HCV) have been hindered by the propensity of the virus to evade host immune responses. HCV particles in serum and in cell culture associate with lipoproteins, which contribute to viral entry. Lipoprotein association has also been proposed to mediate viral evasion of the humoral immune response, though the mechanisms are poorly defined. METHODS We used small interfering RNAs to reduce levels of apolipoprotein E (apoE) in cell culture-derived HCV-producing Huh7.5-derived hepatoma cells and confirmed its depletion by immunoblot analyses of purified viral particles. Before infection of naïve hepatoma cells, we exposed cell culture-derived HCV strains of different genotypes, subtypes, and variants to serum and polyclonal and monoclonal antibodies isolated from patients with chronic HCV infection. We analyzed the interaction of apoE with viral envelope glycoprotein E2 and HCV virions by immunoprecipitation. RESULTS Through loss-of-function studies on patient-derived HCV variants of several genotypes and subtypes, we found that the HCV particle apoE allows the virus to avoid neutralization by patient-derived antibodies. Functional studies with human monoclonal antiviral antibodies showed that conformational epitopes of envelope glycoprotein E2 domains B and C were exposed after depletion of apoE. The level and conformation of virion-associated apoE affected the ability of the virus to escape neutralization by antibodies. CONCLUSIONS In cell-infection studies, we found that HCV-associated apoE helps the virus avoid neutralization by antibodies against HCV isolated from chronically infected patients. This method of immune evasion poses a challenge for the development of HCV vaccines.
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Affiliation(s)
- Catherine Fauvelle
- Inserm, U1110, Institut de Recherche sur les Maladies Virales et Hépatiques, Strasbourg, France; Université de Strasbourg, Strasbourg, France
| | - Daniel J Felmlee
- Inserm, U1110, Institut de Recherche sur les Maladies Virales et Hépatiques, Strasbourg, France; Université de Strasbourg, Strasbourg, France; University of Plymouth, Centre for Biomedical Research, Plymouth, UK
| | - Emilie Crouchet
- Inserm, U1110, Institut de Recherche sur les Maladies Virales et Hépatiques, Strasbourg, France; Université de Strasbourg, Strasbourg, France
| | - JiYoung Lee
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Heidelberg, Germany
| | - Laura Heydmann
- Inserm, U1110, Institut de Recherche sur les Maladies Virales et Hépatiques, Strasbourg, France; Université de Strasbourg, Strasbourg, France
| | - Mathieu Lefèvre
- Inserm, U1110, Institut de Recherche sur les Maladies Virales et Hépatiques, Strasbourg, France; Université de Strasbourg, Strasbourg, France
| | - Andrea Magri
- MRC, University of Glasgow, Centre for Virus Research, Glasgow, UK
| | - Marie-Sophie Hiet
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Heidelberg, Germany
| | - Isabel Fofana
- Inserm, U1110, Institut de Recherche sur les Maladies Virales et Hépatiques, Strasbourg, France; Université de Strasbourg, Strasbourg, France
| | - François Habersetzer
- Inserm, U1110, Institut de Recherche sur les Maladies Virales et Hépatiques, Strasbourg, France; Université de Strasbourg, Strasbourg, France; Institut Hospitalo-Universitaire, Pôle Hépato-digestif, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Steven K H Foung
- Department of Pathology, Stanford University School of Medicine, Stanford, California
| | - Ross Milne
- Department of Pathology and Laboratory Medicine, University of Ottawa Heart Institute, Ottawa, Ontario, Canada
| | - Arvind H Patel
- MRC, University of Glasgow, Centre for Virus Research, Glasgow, UK
| | - Koen Vercauteren
- Center for Vaccinology, Ghent University, Ghent University Hospital, Ghent, Belgium
| | - Philip Meuleman
- Center for Vaccinology, Ghent University, Ghent University Hospital, Ghent, Belgium
| | - Mirjam B Zeisel
- Inserm, U1110, Institut de Recherche sur les Maladies Virales et Hépatiques, Strasbourg, France; Université de Strasbourg, Strasbourg, France
| | - Ralf Bartenschlager
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Heidelberg, Germany
| | - Catherine Schuster
- Inserm, U1110, Institut de Recherche sur les Maladies Virales et Hépatiques, Strasbourg, France; Université de Strasbourg, Strasbourg, France
| | - Thomas F Baumert
- Inserm, U1110, Institut de Recherche sur les Maladies Virales et Hépatiques, Strasbourg, France; Université de Strasbourg, Strasbourg, France; Institut Hospitalo-Universitaire, Pôle Hépato-digestif, Hôpitaux Universitaires de Strasbourg, Strasbourg, France.
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195
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Abstract
Many viruses replicate and assemble in subcellular microenvironments called virus factories or ‘viroplasm.’ Virus factories increase the efficiency of replication and at the same time protect viruses from antiviral defenses. We describe how viruses reorganize cellular membrane compartments and cytoskeleton to generate these ‘mini-organelles’ and how these rearrangements parallel cellular responses to stress such as protein aggregation and DNA damage.
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196
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Schmid B, Rinas M, Ruggieri A, Acosta EG, Bartenschlager M, Reuter A, Fischl W, Harder N, Bergeest JP, Flossdorf M, Rohr K, Höfer T, Bartenschlager R. Live Cell Analysis and Mathematical Modeling Identify Determinants of Attenuation of Dengue Virus 2'-O-Methylation Mutant. PLoS Pathog 2015; 11:e1005345. [PMID: 26720415 PMCID: PMC4697809 DOI: 10.1371/journal.ppat.1005345] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 11/26/2015] [Indexed: 11/19/2022] Open
Abstract
Dengue virus (DENV) is the most common mosquito-transmitted virus infecting ~390 million people worldwide. In spite of this high medical relevance, neither a vaccine nor antiviral therapy is currently available. DENV elicits a strong interferon (IFN) response in infected cells, but at the same time actively counteracts IFN production and signaling. Although the kinetics of activation of this innate antiviral defense and the timing of viral counteraction critically determine the magnitude of infection and thus disease, quantitative and kinetic analyses are lacking and it remains poorly understood how DENV spreads in IFN-competent cell systems. To dissect the dynamics of replication versus antiviral defense at the single cell level, we generated a fully viable reporter DENV and host cells with authentic reporters for IFN-stimulated antiviral genes. We find that IFN controls DENV infection in a kinetically determined manner that at the single cell level is highly heterogeneous and stochastic. Even at high-dose, IFN does not fully protect all cells in the culture and, therefore, viral spread occurs even in the face of antiviral protection of naïve cells by IFN. By contrast, a vaccine candidate DENV mutant, which lacks 2’-O-methylation of viral RNA is profoundly attenuated in IFN-competent cells. Through mathematical modeling of time-resolved data and validation experiments we show that the primary determinant for attenuation is the accelerated kinetics of IFN production. This rapid induction triggered by mutant DENV precedes establishment of IFN-resistance in infected cells, thus causing a massive reduction of virus production rate. In contrast, accelerated protection of naïve cells by paracrine IFN action has negligible impact. In conclusion, these results show that attenuation of the 2’-O-methylation DENV mutant is primarily determined by kinetics of autocrine IFN action on infected cells. Dengue virus (DENV) infection is a global health problem for which no selective therapy or vaccine exists. The magnitude of infection critically depends on the induction kinetics of the interferon (IFN) response and the kinetics of viral countermeasures. Here we established a novel live cell imaging system to dissect the dynamics of this interplay. We find that IFN controls DENV infection in a kinetically determined manner. At the single cell level, the IFN response is highly heterogeneous and stochastic, likely accounting for viral spread in the presence of IFN. Mathematical modeling and validation experiments show that the kinetics of activation of the IFN response critically determines control of virus replication and spread. A vaccine candidate DENV mutant lacking 2’-O-methylation of viral RNA is profoundly attenuated in IFN-competent cells. This attenuation is primarily due to accelerated kinetics of IFN production acting on infected cells in an autocrine manner. In contrast, accelerated protection of naïve cells by paracrine IFN action has negligible impact. Thus, attenuation of the 2’-O-methylation DENV mutant is primarily determined by kinetics of autocrine IFN action on infected cells.
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Affiliation(s)
- Bianca Schmid
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany
| | - Melanie Rinas
- Division of Theoretical Systems Biology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- BioQuant Center, University of Heidelberg, Heidelberg, Germany
| | - Alessia Ruggieri
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany
| | - Eliana Gisela Acosta
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany
| | - Marie Bartenschlager
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany
| | - Antje Reuter
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany
| | - Wolfgang Fischl
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany
| | - Nathalie Harder
- BioQuant Center, University of Heidelberg, Heidelberg, Germany
- Department of Bioinformatics and Functional Genomics, Biomedical Computer Vision Group, Institute of Pharmacy and Molecular Biotechnology, University of Heidelberg, Heidelberg, Germany
| | - Jan-Philip Bergeest
- BioQuant Center, University of Heidelberg, Heidelberg, Germany
- Department of Bioinformatics and Functional Genomics, Biomedical Computer Vision Group, Institute of Pharmacy and Molecular Biotechnology, University of Heidelberg, Heidelberg, Germany
| | - Michael Flossdorf
- Division of Theoretical Systems Biology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- BioQuant Center, University of Heidelberg, Heidelberg, Germany
| | - Karl Rohr
- BioQuant Center, University of Heidelberg, Heidelberg, Germany
- Department of Bioinformatics and Functional Genomics, Biomedical Computer Vision Group, Institute of Pharmacy and Molecular Biotechnology, University of Heidelberg, Heidelberg, Germany
| | - Thomas Höfer
- Division of Theoretical Systems Biology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- BioQuant Center, University of Heidelberg, Heidelberg, Germany
- * E-mail: (TH); (RB)
| | - Ralf Bartenschlager
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany
- * E-mail: (TH); (RB)
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197
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Bender S, Reuter A, Eberle F, Einhorn E, Binder M, Bartenschlager R. Activation of Type I and III Interferon Response by Mitochondrial and Peroxisomal MAVS and Inhibition by Hepatitis C Virus. PLoS Pathog 2015; 11:e1005264. [PMID: 26588843 PMCID: PMC4654527 DOI: 10.1371/journal.ppat.1005264] [Citation(s) in RCA: 112] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 10/19/2015] [Indexed: 12/22/2022] Open
Abstract
Sensing viruses by pattern recognition receptors (PRR) triggers the innate immune system of the host cell and activates immune signaling cascades such as the RIG-I/IRF3 pathway. Mitochondrial antiviral-signaling protein (MAVS, also known as IPS-1, Cardif, and VISA) is the crucial adaptor protein of this pathway localized on mitochondria, peroxisomes and mitochondria-associated membranes of the endoplasmic reticulum. Activation of MAVS leads to the production of type I and type III interferons (IFN) as well as IFN stimulated genes (ISGs). To refine the role of MAVS subcellular localization for the induction of type I and III IFN responses in hepatocytes and its counteraction by the hepatitis C virus (HCV), we generated various functional and genetic knock-out cell systems that were reconstituted to express mitochondrial (mito) or peroxisomal (pex) MAVS, exclusively. Upon infection with diverse RNA viruses we found that cells exclusively expressing pexMAVS mounted sustained expression of type I and III IFNs to levels comparable to cells exclusively expressing mitoMAVS. To determine whether viral counteraction of MAVS is affected by its subcellular localization we employed infection of cells with HCV, a major causative agent of chronic liver disease with a high propensity to establish persistence. This virus efficiently cleaves MAVS via a viral protease residing in its nonstructural protein 3 (NS3) and this strategy is thought to contribute to the high persistence of this virus. We found that both mito- and pexMAVS were efficiently cleaved by NS3 and this cleavage was required to suppress activation of the IFN response. Taken together, our findings indicate comparable activation of the IFN response by pex- and mitoMAVS in hepatocytes and efficient counteraction of both MAVS species by the HCV NS3 protease. Mammalian cells developed several defense mechanisms against viral infection. One major strategy involves pattern recognition receptors (PRRs) recognizing non-self motifs in viral RNA and triggering the production of type I and III interferon (IFN) that induce an antiviral state. One central signaling molecule in this cascade is MAVS (Mitochondrial Antiviral Signaling protein), residing on mitochondria, mitochondria-associated membranes of the endoplasmic reticulum, and peroxisomes. Here we characterized the role of mitochondrial and peroxisomal MAVS for the activation of the IFN response and their counteraction by the hepatitis C virus (HCV), a major causative agent of chronic liver disease with a high propensity to establish persistence. By using various functional and genetic knock-out cell systems reconstituted to express exclusively mitochondrial or peroxisomal MAVS, we observed comparable activation of type I and III IFN response by either MAVS species. In addition, we found that the HCV protease residing in nonstructural protein 3 (NS3) efficiently cleaves MAVS independent from its subcellular localization. This cleavage is required for suppression of the IFN response and might contribute to HCV persistence. Our results indicate a largely localization-independent activation of the IFN response by MAVS in hepatocytes and its efficient counteraction by the HCV NS3 protease.
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Affiliation(s)
- Silke Bender
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Heidelberg, Germany
- Division of Virus-Associated Carcinogenesis, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Antje Reuter
- Division of Virus-Associated Carcinogenesis, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Florian Eberle
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Heidelberg, Germany
| | - Evelyne Einhorn
- Division of Virus-Associated Carcinogenesis, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Master BioSciences, Département de Biologie, École Normale Supérieure de Lyon, Université de Lyon, Lyon, France
| | - Marco Binder
- Division of Virus-Associated Carcinogenesis, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Ralf Bartenschlager
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Heidelberg, Germany
- Division of Virus-Associated Carcinogenesis, German Cancer Research Center (DKFZ), Heidelberg, Germany
- * E-mail:
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198
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Host-Targeting Agents to Prevent and Cure Hepatitis C Virus Infection. Viruses 2015; 7:5659-85. [PMID: 26540069 PMCID: PMC4664971 DOI: 10.3390/v7112898] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Revised: 09/25/2015] [Accepted: 10/19/2015] [Indexed: 12/13/2022] Open
Abstract
Chronic hepatitis C virus (HCV) infection is a major cause of liver cirrhosis and hepatocellular carcinoma (HCC) which are leading indications of liver transplantation (LT). To date, there is no vaccine to prevent HCV infection and LT is invariably followed by infection of the liver graft. Within the past years, direct-acting antivirals (DAAs) have had a major impact on the management of chronic hepatitis C, which has become a curable disease in the majority of DAA-treated patients. In contrast to DAAs that target viral proteins, host-targeting agents (HTAs) interfere with cellular factors involved in the viral life cycle. By acting through a complementary mechanism of action and by exhibiting a generally higher barrier to resistance, HTAs offer a prospective option to prevent and treat viral resistance. Indeed, given their complementary mechanism of action, HTAs and DAAs can act in a synergistic manner to reduce viral loads. This review summarizes the different classes of HTAs against HCV infection that are in preclinical or clinical development and highlights their potential to prevent HCV infection, e.g., following LT, and to tailor combination treatments to cure chronic HCV infection.
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199
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Villareal VA, Rodgers MA, Costello DA, Yang PL. Targeting host lipid synthesis and metabolism to inhibit dengue and hepatitis C viruses. Antiviral Res 2015; 124:110-21. [PMID: 26526588 DOI: 10.1016/j.antiviral.2015.10.013] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 10/08/2015] [Accepted: 10/11/2015] [Indexed: 12/16/2022]
Abstract
Lipids are necessary for every step in the replication cycle of hepatitis C virus (HCV) and dengue virus (DENV), members of the family Flaviviridae. Recent studies have demonstrated that discrete steps in the replication cycles of these viruses can be inhibited by pharmacological agents that target host factors mediating lipid synthesis, metabolism, trafficking, and signal transduction. Despite this, targeting host lipid metabolism and trafficking as an antiviral strategy by blockade of entire pathways may be limited due to host toxicity. Knowledge of the molecular details of lipid structure and function in replication and the mechanisms whereby specific lipids are generated and trafficked to the relevant sites may enable more targeted antiviral strategies without global effects on the host cell. In this review, we discuss lipids demonstrated to be critical to the replication cycles of HCV and DENV and highlight potential areas for anti-viral development. This review article forms part of a symposium on flavivirus drug discovery in Antiviral Research.
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Affiliation(s)
- Valerie A Villareal
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, USA
| | - Mary A Rodgers
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, USA
| | - Deirdre A Costello
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, USA
| | - Priscilla L Yang
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, USA.
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Carnero E, Fortes P. HCV infection, IFN response and the coding and non-coding host cell genome. Virus Res 2015; 212:85-102. [PMID: 26454190 DOI: 10.1016/j.virusres.2015.10.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Accepted: 10/01/2015] [Indexed: 02/07/2023]
Abstract
HCV is an ideal model to study how the infected cell is altered to allow the establishment of a chronic infection. After infection, the transcriptome of the cell changes in response to the virus or to the antiviral pathways induced by infection. The cell has evolved to sense HCV soon after infection and to activate antiviral pathways. In turn, HCV has evolved to block the antiviral pathways induced by the cell and, at the same time, to use some for its own benefit. In this review, we summarize the proviral and antiviral factors induced in HCV infected cells. These factors can be proteins and microRNAs, but also long noncoding RNAs (lncRNAs) that are induced by infection. Interestingly, several of the lncRNAs upregulated after HCV infection have oncogenic functions, suggesting that upregulation of lncRNAs could explain, at least in part, the increased rate of liver tumors observed in HCV-infected patients. Other lncRNAs induced by HCV infection may regulate the expression of coding genes required for replication or control genes involved in the cellular antiviral response. Given the evolutionary pressure imposed by viral infections and that lncRNAs are specially targeted by evolution, we believe that the study of proviral and antiviral lncRNAs may lead to unexpected discoveries that may have a strong impact on basic science and translational research.
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Affiliation(s)
- Elena Carnero
- Center for Applied Medical Research (CIMA) and Navarra Institute for Health Research (IdiSNA), Department of Gene Therapy and Hepatology, University of Navarra, Pamplona, Spain
| | - Puri Fortes
- Center for Applied Medical Research (CIMA) and Navarra Institute for Health Research (IdiSNA), Department of Gene Therapy and Hepatology, University of Navarra, Pamplona, Spain.
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