1
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Wang C, Chen Y, Hu S, Liu X. Insights into the function of ESCRT and its role in enveloped virus infection. Front Microbiol 2023; 14:1261651. [PMID: 37869652 PMCID: PMC10587442 DOI: 10.3389/fmicb.2023.1261651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 09/20/2023] [Indexed: 10/24/2023] Open
Abstract
The endosomal sorting complex required for transport (ESCRT) is an essential molecular machinery in eukaryotic cells that facilitates the invagination of endosomal membranes, leading to the formation of multivesicular bodies (MVBs). It participates in various cellular processes, including lipid bilayer remodeling, cytoplasmic separation, autophagy, membrane fission and re-modeling, plasma membrane repair, as well as the invasion, budding, and release of certain enveloped viruses. The ESCRT complex consists of five complexes, ESCRT-0 to ESCRT-III and VPS4, along with several accessory proteins. ESCRT-0 to ESCRT-II form soluble complexes that shuttle between the cytoplasm and membranes, mainly responsible for recruiting and transporting membrane proteins and viral particles, as well as recruiting ESCRT-III for membrane neck scission. ESCRT-III, a soluble monomer, directly participates in vesicle scission and release, while VPS4 hydrolyzes ATP to provide energy for ESCRT-III complex disassembly, enabling recycling. Studies have confirmed the hijacking of ESCRT complexes by enveloped viruses to facilitate their entry, replication, and budding. Recent research has focused on the interaction between various components of the ESCRT complex and different viruses. In this review, we discuss how different viruses hijack specific ESCRT regulatory proteins to impact the viral life cycle, aiming to explore commonalities in the interaction between viruses and the ESCRT system.
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Affiliation(s)
- Chunxuan Wang
- Animal Infectious Disease Laboratory, College of Veterinary Medicine, Yangzhou University, Yangzhou, China
| | - Yu Chen
- Animal Infectious Disease Laboratory, College of Veterinary Medicine, Yangzhou University, Yangzhou, China
| | - Shunlin Hu
- Animal Infectious Disease Laboratory, College of Veterinary Medicine, Yangzhou University, Yangzhou, China
| | - Xiufan Liu
- Animal Infectious Disease Laboratory, College of Veterinary Medicine, Yangzhou University, Yangzhou, China
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou University, Yangzhou, China
- Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, China
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2
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Beavers KM, Van Buren EW, Rossin AM, Emery MA, Veglia AJ, Karrick CE, MacKnight NJ, Dimos BA, Meiling SS, Smith TB, Apprill A, Muller EM, Holstein DM, Correa AMS, Brandt ME, Mydlarz LD. Stony coral tissue loss disease induces transcriptional signatures of in situ degradation of dysfunctional Symbiodiniaceae. Nat Commun 2023; 14:2915. [PMID: 37217477 DOI: 10.1038/s41467-023-38612-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Accepted: 05/10/2023] [Indexed: 05/24/2023] Open
Abstract
Stony coral tissue loss disease (SCTLD), one of the most pervasive and virulent coral diseases on record, affects over 22 species of reef-building coral and is decimating reefs throughout the Caribbean. To understand how different coral species and their algal symbionts (family Symbiodiniaceae) respond to this disease, we examine the gene expression profiles of colonies of five species of coral from a SCTLD transmission experiment. The included species vary in their purported susceptibilities to SCTLD, and we use this to inform gene expression analyses of both the coral animal and their Symbiodiniaceae. We identify orthologous coral genes exhibiting lineage-specific differences in expression that correlate to disease susceptibility, as well as genes that are differentially expressed in all coral species in response to SCTLD infection. We find that SCTLD infection induces increased expression of rab7, an established marker of in situ degradation of dysfunctional Symbiodiniaceae, in all coral species accompanied by genus-level shifts in Symbiodiniaceae photosystem and metabolism gene expression. Overall, our results indicate that SCTLD infection induces symbiophagy across coral species and that the severity of disease is influenced by Symbiodiniaceae identity.
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Affiliation(s)
- Kelsey M Beavers
- Biology Department, University of Texas at Arlington, Arlington, TX, USA
| | - Emily W Van Buren
- Biology Department, University of Texas at Arlington, Arlington, TX, USA
| | - Ashley M Rossin
- Department of Oceanography and Coastal Sciences, Louisiana State University, Baton Rouge, LA, USA
| | - Madison A Emery
- Biology Department, University of Texas at Arlington, Arlington, TX, USA
| | - Alex J Veglia
- Department of BioSciences, Rice University, Houston, TX, USA
| | - Carly E Karrick
- Department of BioSciences, Rice University, Houston, TX, USA
| | | | - Bradford A Dimos
- Biology Department, University of Texas at Arlington, Arlington, TX, USA
| | - Sonora S Meiling
- Center for Marine and Environmental Studies, University of the Virgin Islands, St. Thomas, USVI, USA
| | - Tyler B Smith
- Center for Marine and Environmental Studies, University of the Virgin Islands, St. Thomas, USVI, USA
| | - Amy Apprill
- Marine Chemistry and Geochemistry Department, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | | | - Daniel M Holstein
- Department of Oceanography and Coastal Sciences, Louisiana State University, Baton Rouge, LA, USA
| | | | - Marilyn E Brandt
- Center for Marine and Environmental Studies, University of the Virgin Islands, St. Thomas, USVI, USA
| | - Laura D Mydlarz
- Biology Department, University of Texas at Arlington, Arlington, TX, USA.
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3
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Muraleedharan A, Vanderperre B. The endo-lysosomal system in Parkinson's disease: expanding the horizon. J Mol Biol 2023:168140. [PMID: 37148997 DOI: 10.1016/j.jmb.2023.168140] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 04/22/2023] [Accepted: 04/27/2023] [Indexed: 05/08/2023]
Abstract
Parkinson's disease (PD) is the second most common neurodegenerative disorder after Alzheimer's disease, and its prevalence is increasing with age. A wealth of genetic evidence indicates that the endo-lysosomal system is a major pathway driving PD pathogenesis with a growing number of genes encoding endo-lysosomal proteins identified as risk factors for PD, making it a promising target for therapeutic intervention. However, detailed knowledge and understanding of the molecular mechanisms linking these genes to the disease are available for only a handful of them (e.g. LRRK2, GBA1, VPS35). Taking on the challenge of studying poorly characterized genes and proteins can be daunting, due to the limited availability of tools and knowledge from previous literature. This review aims at providing a valuable source of molecular and cellular insights into the biology of lesser-studied PD-linked endo-lysosomal genes, to help and encourage researchers in filling the knowledge gap around these less popular genetic players. Specific endo-lysosomal pathways discussed range from endocytosis, sorting, and vesicular trafficking to the regulation of membrane lipids of these membrane-bound organelles and the specific enzymatic activities they contain. We also provide perspectives on future challenges that the community needs to tackle and propose approaches to move forward in our understanding of these poorly studied endo-lysosomal genes. This will help harness their potential in designing innovative and efficient treatments to ultimately re-establish neuronal homeostasis in PD but also other diseases involving endo-lysosomal dysfunction.
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Affiliation(s)
- Amitha Muraleedharan
- Centre d'Excellence en Recherche sur les Maladies Orphelines - Fondation Courtois and Biological Sciences Department, Université du Québec à Montréal
| | - Benoît Vanderperre
- Centre d'Excellence en Recherche sur les Maladies Orphelines - Fondation Courtois and Biological Sciences Department, Université du Québec à Montréal
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4
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Ruan Z, Liang Y, Chen Z, Yin J, Li C, Pan P, Zhang Q, Wu J, Luo Z. Enterovirus 71 non-structural protein 3A hijacks vacuolar protein sorting 25 to boost exosome biogenesis to facilitate viral replication. Front Microbiol 2022; 13:1024899. [PMID: 36274707 PMCID: PMC9581156 DOI: 10.3389/fmicb.2022.1024899] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Accepted: 09/21/2022] [Indexed: 11/16/2022] Open
Abstract
Human enterovirus 71 (EV71) is one of the major agents of the hand, foot, and mouth disease (HFMD), and occasionally causes severe neurological complications. There is clinical evidence that EV71 infection increases the exosomes in the serum of severe HFMD patients, suggesting a role of exosomes in EV71 pathogenesis. However, the relationship between exosomes and EV71 replication remains elusive. In this study, we initially found that EV71 infection elevated exosome biogenesis in the cultured cells. Among EV71 non-structural proteins, we identified EV71 3A, but not 3B, constitutively promoted exosome secretion. In detail, EV71 3A protein interacted with vacuolar protein sorting 25 (VPS25), while knock-down of VPS25 reduced EV71 3A protein- and EV71-induced exosome production. Further studies revealed VPS25 located on exosomes and its expression correlated to the exosome production. During EV71 infection, knock-down of VPS25 decreased exosome biogenesis to attenuate viral replication. Consistently, GW4869, an exosome inhibitor, exerted an obviously antiviral activity against EV71 replication companied with the decrease of exosome secretion or formation. These findings suggest the binding of EV71 3A and VPS25 benefited exosome biogenesis, thereby boosting viral replication. This study uncovers a novel mechanism underlying EV71-mediated exosomes in the regulation of viral replication, which provides potential anti-viral strategies against the EV71 infection and transmission in HFMD.
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Affiliation(s)
- Zhihui Ruan
- Guangdong Provincial Key Laboratory of Virology, Institute of Medical Microbiology, Jinan University, Guangzhou, China
| | - Yicong Liang
- Guangdong Provincial Key Laboratory of Virology, Institute of Medical Microbiology, Jinan University, Guangzhou, China
| | - Zicong Chen
- Guangdong Provincial Key Laboratory of Virology, Institute of Medical Microbiology, Jinan University, Guangzhou, China
| | - Jialing Yin
- Guangdong Provincial Key Laboratory of Virology, Institute of Medical Microbiology, Jinan University, Guangzhou, China
| | - Chengcheng Li
- Guangdong Provincial Key Laboratory of Virology, Institute of Medical Microbiology, Jinan University, Guangzhou, China
| | - Pan Pan
- Guangdong Provincial Key Laboratory of Virology, Institute of Medical Microbiology, Jinan University, Guangzhou, China
- Foshan Institute of Medical Microbiology, Foshan, China
| | - Qiwei Zhang
- Guangdong Provincial Key Laboratory of Virology, Institute of Medical Microbiology, Jinan University, Guangzhou, China
- Foshan Institute of Medical Microbiology, Foshan, China
| | - Jianguo Wu
- Guangdong Provincial Key Laboratory of Virology, Institute of Medical Microbiology, Jinan University, Guangzhou, China
- Foshan Institute of Medical Microbiology, Foshan, China
- Jianguo Wu,
| | - Zhen Luo
- Guangdong Provincial Key Laboratory of Virology, Institute of Medical Microbiology, Jinan University, Guangzhou, China
- Foshan Institute of Medical Microbiology, Foshan, China
- *Correspondence: Zhen Luo,
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5
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Vogiatzis S, Celestino M, Trevisan M, Magro G, Del Vecchio C, Erdengiz D, Palù G, Parolin C, Maguire-Zeiss K, Calistri A. Lentiviral Vectors Expressing Chimeric NEDD4 Ubiquitin Ligases: An Innovative Approach for Interfering with Alpha-Synuclein Accumulation. Cells 2021; 10:cells10113256. [PMID: 34831478 PMCID: PMC8624294 DOI: 10.3390/cells10113256] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 11/14/2021] [Accepted: 11/18/2021] [Indexed: 11/25/2022] Open
Abstract
One of the main pathological features of Parkinson’s disease (PD) is a diffuse accumulation of alpha-synuclein (aS) aggregates in neurons. The NEDD4 E3 Ub ligase promotes aS degradation by the endosomal–lysosomal route. Interestingly, NEDD4, as well as being a small molecule able to trigger its functions, is protective against human aS toxicity in evolutionary distant models. While pharmacological activation of E3 enzymes is not easy to achieve, their flexibility and the lack of “consensus” motifs for Ub-conjugation allow the development of engineered Ub-ligases, able to target proteins of interest. We developed lentiviral vectors, encoding well-characterized anti-human aS scFvs fused in frame to the NEDD4 catalytic domain (ubiquibodies), in order to target ubiquitinate aS. We demonstrate that, while all generated ubiquibodies bind to and ubiquitinate aS, the one directed against the non-amyloid component (NAC) of aS (Nac32HECT) affects aS’s intracellular levels. Furthermore, Nac32HECT expression partially rescues aS’s overexpression or mutation toxicity in neural stem cells. Overall, our data suggest that ubiquibodies, and Nac32HECT in particular, represent a valid platform for interfering with the effects of aS’s accumulation and aggregation in neurons.
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Affiliation(s)
- Stefania Vogiatzis
- Department of Molecular Medicine, University of Padua, Via A. Gabelli 63, 35121 Padua, Italy; (S.V.); (M.C.); (M.T.); (G.M.); (C.D.V.); (G.P.); (C.P.)
| | - Michele Celestino
- Department of Molecular Medicine, University of Padua, Via A. Gabelli 63, 35121 Padua, Italy; (S.V.); (M.C.); (M.T.); (G.M.); (C.D.V.); (G.P.); (C.P.)
| | - Marta Trevisan
- Department of Molecular Medicine, University of Padua, Via A. Gabelli 63, 35121 Padua, Italy; (S.V.); (M.C.); (M.T.); (G.M.); (C.D.V.); (G.P.); (C.P.)
| | - Gloria Magro
- Department of Molecular Medicine, University of Padua, Via A. Gabelli 63, 35121 Padua, Italy; (S.V.); (M.C.); (M.T.); (G.M.); (C.D.V.); (G.P.); (C.P.)
| | - Claudia Del Vecchio
- Department of Molecular Medicine, University of Padua, Via A. Gabelli 63, 35121 Padua, Italy; (S.V.); (M.C.); (M.T.); (G.M.); (C.D.V.); (G.P.); (C.P.)
| | - Deran Erdengiz
- Department of Neuroscience, Georgetown University Medical Center, 3970 Reservoir Rd NW, NRB, EP04, Washington, DC 20057, USA; (D.E.); (K.M.-Z.)
| | - Giorgio Palù
- Department of Molecular Medicine, University of Padua, Via A. Gabelli 63, 35121 Padua, Italy; (S.V.); (M.C.); (M.T.); (G.M.); (C.D.V.); (G.P.); (C.P.)
| | - Cristina Parolin
- Department of Molecular Medicine, University of Padua, Via A. Gabelli 63, 35121 Padua, Italy; (S.V.); (M.C.); (M.T.); (G.M.); (C.D.V.); (G.P.); (C.P.)
| | - Kathleen Maguire-Zeiss
- Department of Neuroscience, Georgetown University Medical Center, 3970 Reservoir Rd NW, NRB, EP04, Washington, DC 20057, USA; (D.E.); (K.M.-Z.)
| | - Arianna Calistri
- Department of Molecular Medicine, University of Padua, Via A. Gabelli 63, 35121 Padua, Italy; (S.V.); (M.C.); (M.T.); (G.M.); (C.D.V.); (G.P.); (C.P.)
- Correspondence: ; Tel.: +39-049-827-2341
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6
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The Role of Exosome and the ESCRT Pathway on Enveloped Virus Infection. Int J Mol Sci 2021; 22:ijms22169060. [PMID: 34445766 PMCID: PMC8396519 DOI: 10.3390/ijms22169060] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 08/20/2021] [Accepted: 08/20/2021] [Indexed: 02/06/2023] Open
Abstract
The endosomal sorting complex required for transport (ESCRT) system consists of peripheral membrane protein complexes ESCRT-0, -I, -II, -III VPS4-VTA1, and ALIX homodimer. This system plays an important role in the degradation of non-essential or dangerous plasma membrane proteins, the biogenesis of lysosomes and yeast vacuoles, the budding of most enveloped viruses, and promoting membrane shedding of cytokinesis. Recent results show that exosomes and the ESCRT pathway play important roles in virus infection. This review mainly focuses on the roles of exosomes and the ESCRT pathway in virus assembly, budding, and infection of enveloped viruses. The elaboration of the mechanism of exosomes and the ESCRT pathway in some enveloped viruses provides important implications for the further study of the infection mechanism of other enveloped viruses.
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7
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Welker L, Paillart JC, Bernacchi S. Importance of Viral Late Domains in Budding and Release of Enveloped RNA Viruses. Viruses 2021; 13:1559. [PMID: 34452424 PMCID: PMC8402826 DOI: 10.3390/v13081559] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 08/04/2021] [Accepted: 08/05/2021] [Indexed: 01/09/2023] Open
Abstract
Late assembly (L) domains are conserved sequences that are necessary for the late steps of viral replication, acting like cellular adaptors to engage the ESCRT membrane fission machinery that promote virion release. These short sequences, whose mutation or deletion produce the accumulation of immature virions at the plasma membrane, were firstly identified within retroviral Gag precursors, and in a further step, also in structural proteins of many other enveloped RNA viruses including arenaviruses, filoviruses, rhabdoviruses, reoviruses, and paramyxoviruses. Three classes of L domains have been identified thus far (PT/SAP, YPXnL/LXXLF, and PPxY), even if it has recently been suggested that other motifs could act as L domains. Here, we summarize the current state of knowledge of the different types of L domains and their cellular partners in the budding events of RNA viruses, with a particular focus on retroviruses.
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Affiliation(s)
| | | | - Serena Bernacchi
- Architecture et Réactivité de l’ARN, UPR 9002, IBMC, CNRS, Université de Strasbourg, F-67000 Strasbourg, France; (L.W.); (J.-C.P.)
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8
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Ilaprazole and other novel prazole-based compounds that bind Tsg101 inhibit viral budding of HSV-1/2 and HIV from cells. J Virol 2021; 95:JVI.00190-21. [PMID: 33731460 PMCID: PMC8139698 DOI: 10.1128/jvi.00190-21] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
In many enveloped virus families, including HIV and HSV, a crucial, yet unexploited, step in the viral life cycle is releasing particles from the infected cell membranes. This release process is mediated by host ESCRT complex proteins, which are recruited by viral structural proteins and provides the mechanical means for membrane scission and subsequent viral budding. The prazole drug, tenatoprazole, was previously shown to bind to ESCRT complex member Tsg101 and to quantitatively block the release of infectious HIV-1 from cells in culture. In this report we show that tenatoprazole and a related prazole drug, ilaprazole, effectively block infectious Herpes Simplex Virus (HSV)-1/2 release from Vero cells in culture. By electron microscopy, we found that both prazole drugs block the transit of HSV particles through the cell nuclear membrane resulting in their accumulation in the nucleus. Ilaprazole also quantitatively blocks the release of HIV-1 from 293T cells with an EC50 of 0.8-1.2 μM, which is much more potent than tenatoprazole. Our results indicate that prazole-based compounds may represent a class of drugs with potential to be broad-spectrum antiviral agents against multiple enveloped viruses, by interrupting cellular Tsg101 interaction with maturing virus, thus blocking the budding process that releases particles from the cell.ImportanceThese results provide the basis for the development of drugs that target enveloped virus budding that can be used ultimately to control multiple virus infections in humans.
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9
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Why Cells and Viruses Cannot Survive without an ESCRT. Cells 2021; 10:cells10030483. [PMID: 33668191 PMCID: PMC7995964 DOI: 10.3390/cells10030483] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 02/19/2021] [Accepted: 02/21/2021] [Indexed: 12/15/2022] Open
Abstract
Intracellular organelles enwrapped in membranes along with a complex network of vesicles trafficking in, out and inside the cellular environment are one of the main features of eukaryotic cells. Given their central role in cell life, compartmentalization and mechanisms allowing their maintenance despite continuous crosstalk among different organelles have been deeply investigated over the past years. Here, we review the multiple functions exerted by the endosomal sorting complex required for transport (ESCRT) machinery in driving membrane remodeling and fission, as well as in repairing physiological and pathological membrane damages. In this way, ESCRT machinery enables different fundamental cellular processes, such as cell cytokinesis, biogenesis of organelles and vesicles, maintenance of nuclear–cytoplasmic compartmentalization, endolysosomal activity. Furthermore, we discuss some examples of how viruses, as obligate intracellular parasites, have evolved to hijack the ESCRT machinery or part of it to execute/optimize their replication cycle/infection. A special emphasis is given to the herpes simplex virus type 1 (HSV-1) interaction with the ESCRT proteins, considering the peculiarities of this interplay and the need for HSV-1 to cross both the nuclear-cytoplasmic and the cytoplasmic-extracellular environment compartmentalization to egress from infected cells.
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10
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The Interplay between ESCRT and Viral Factors in the Enveloped Virus Life Cycle. Viruses 2021; 13:v13020324. [PMID: 33672541 PMCID: PMC7923801 DOI: 10.3390/v13020324] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Revised: 02/08/2021] [Accepted: 02/12/2021] [Indexed: 12/13/2022] Open
Abstract
Viruses are obligate parasites that rely on host cellular factors to replicate and spread. The endosomal sorting complexes required for transport (ESCRT) system, which is classically associated with sorting and downgrading surface proteins, is one of the host machineries hijacked by viruses across diverse families. Knowledge gained from research into ESCRT and viruses has, in turn, greatly advanced our understanding of many other cellular functions in which the ESCRT pathway is involved, e.g., cytokinesis. This review highlights the interplay between the ESCRT pathway and the viral factors of enveloped viruses with a special emphasis on retroviruses.
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11
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Meusser B, Purfuerst B, Luft FC. HIV-1 Gag release from yeast reveals ESCRT interaction with the Gag N-terminal protein region. J Biol Chem 2020; 295:17950-17972. [PMID: 32994219 PMCID: PMC7939435 DOI: 10.1074/jbc.ra120.014710] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 09/25/2020] [Indexed: 11/30/2022] Open
Abstract
The HIV-1 protein Gag assembles at the plasma membrane and drives virion budding, assisted by the cellular endosomal complex required for transport (ESCRT) proteins. Two ESCRT proteins, TSG101 and ALIX, bind to the Gag C-terminal p6 peptide. TSG101 binding is important for efficient HIV-1 release, but how ESCRTs contribute to the budding process and how their activity is coordinated with Gag assembly is poorly understood. Yeast, allowing genetic manipulation that is not easily available in human cells, has been used to characterize the cellular ESCRT function. Previous work reported Gag budding from yeast spheroplasts, but Gag release was ESCRT-independent. We developed a yeast model for ESCRT-dependent Gag release. We combined yeast genetics and Gag mutational analysis with Gag-ESCRT binding studies and the characterization of Gag-plasma membrane binding and Gag release. With our system, we identified a previously unknown interaction between ESCRT proteins and the Gag N-terminal protein region. Mutations in the Gag-plasma membrane-binding matrix domain that reduced Gag-ESCRT binding increased Gag-plasma membrane binding and Gag release. ESCRT knockout mutants showed that the release enhancement was an ESCRT-dependent effect. Similarly, matrix mutation enhanced Gag release from human HEK293 cells. Release enhancement partly depended on ALIX binding to p6, although binding site mutation did not impair WT Gag release. Accordingly, the relative affinity for matrix compared with p6 in GST-pulldown experiments was higher for ALIX than for TSG101. We suggest that a transient matrix-ESCRT interaction is replaced when Gag binds to the plasma membrane. This step may activate ESCRT proteins and thereby coordinate ESCRT function with virion assembly.
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Affiliation(s)
- Birgit Meusser
- Charité Medical Faculty, Berlin, Germany; Max-Delbrück-Center for Molecular Medicine, Berlin, Germany
| | | | - Friedrich C Luft
- Charité Medical Faculty, Berlin, Germany; Max-Delbrück-Center for Molecular Medicine, Berlin, Germany; Experimental and Clinical Research Center, Berlin, Germany.
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12
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Gupta S, Bendjennat M, Saffarian S. Abrogating ALIX Interactions Results in Stuttering of the ESCRT Machinery. Viruses 2020; 12:v12091032. [PMID: 32948012 PMCID: PMC7551432 DOI: 10.3390/v12091032] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 09/05/2020] [Accepted: 09/11/2020] [Indexed: 02/07/2023] Open
Abstract
Endosomal sorting complexes required for transport (ESCRT) proteins assemble on budding cellular membranes and catalyze their fission. Using live imaging of HIV virions budding from cells, we followed recruitment of ESCRT proteins ALIX, CHMP4B and VPS4. We report that the ESCRT proteins transiently co-localize with virions after completion of virion assembly for durations of 45 ± 30 s. We show that mutagenizing the YP domain of Gag which is the primary ALIX binding site or depleting ALIX from cells results in multiple recruitments of the full ESCRT machinery on the same virion (referred to as stuttering where the number of recruitments to the same virion >3). The stuttering recruitments are approximately 4 ± 3 min apart and have the same stoichiometry of ESCRTs and same residence time (45 ± 30 s) as the single recruitments in wild type interactions. Our observations suggest a role for ALIX during fission and question the linear model of ESCRT recruitment, suggesting instead a more complex co-assembly model.
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Affiliation(s)
- Shilpa Gupta
- Center for Cell and Genome Sciences, University of Utah, Salt Lake City, UT 84112, USA; (S.G.); (M.B.)
- Department of Biology, University of Utah, Salt Lake City, UT 84112, USA
| | - Mourad Bendjennat
- Center for Cell and Genome Sciences, University of Utah, Salt Lake City, UT 84112, USA; (S.G.); (M.B.)
- Radiation Oncology Department, University of Miami, Miami, FL 33136, USA
- Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112, USA
| | - Saveez Saffarian
- Center for Cell and Genome Sciences, University of Utah, Salt Lake City, UT 84112, USA; (S.G.); (M.B.)
- Department of Biology, University of Utah, Salt Lake City, UT 84112, USA
- Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112, USA
- Correspondence:
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13
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Watanabe SM, Strickland M, Tjandra N, Carter CA. RNA Binding Suppresses Tsg101 Recognition of Ub-Modified Gag and Facilitates Recruitment to the Plasma Membrane. Viruses 2020; 12:v12040447. [PMID: 32326417 PMCID: PMC7232412 DOI: 10.3390/v12040447] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 04/07/2020] [Accepted: 04/10/2020] [Indexed: 01/09/2023] Open
Abstract
The ESCRT-I factor Tsg101 is essential for sorting endocytic cargo and is exploited by viral pathogens to facilitate egress from cells. Both the nucleocapsid (NC) domain and p6 domain in HIV-1 Gag contribute to recruitment of the protein. However, the role of NC is unclear when the P(S/T)AP motif in p6 is intact, as the motif recruits Tsg101 directly. The zinc fingers in NC bind RNA and membrane and are critical for budding. Tsg101 can substitute for the distal ZnF (ZnF2) and rescue budding of a mutant made defective by deletion of this element. Here, we report that the ubiquitin (Ub) E2 variant (UEV) domain in Tsg101 binds tRNA in vitro. We confirmed that Tsg101 can substitute for ZnF2 when provided at the viral assembly site as a chimeric Gag-Tsg101 protein (Gag-ΔZnF2-Tsg101) and rescue budding. The UEV was not required in this context; however, mutation of the RNA binding determinants in UEV prevented Tsg101 recruitment from the cell interior when Gag and Tsg101 were co-expressed. The same Tsg101 mutations increased recognition of Gag-Ub, suggesting that tRNA and Ub compete for binding sites. This study identifies a novel Tsg101 binding partner that may contribute to its function in recognition of Ub-modified cargo.
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Affiliation(s)
- Susan M. Watanabe
- Department of Microbiology & Immunology, Renaissance School of Medicine, Stony Brook University, Stony Brook, NY 11794-5222, USA;
| | - Madeleine Strickland
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA;
| | - Nico Tjandra
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA;
- Correspondence: (N.T.); (C.A.C.); Tel.: +1-631-632-8801 (C.A.C.)
| | - Carol A. Carter
- Department of Microbiology & Immunology, Renaissance School of Medicine, Stony Brook University, Stony Brook, NY 11794-5222, USA;
- Correspondence: (N.T.); (C.A.C.); Tel.: +1-631-632-8801 (C.A.C.)
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14
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Meng B, Ip NCY, Abbink TEM, Kenyon JC, Lever AML. ESCRT-II functions by linking to ESCRT-I in human immunodeficiency virus-1 budding. Cell Microbiol 2020; 22:e13161. [PMID: 31922351 PMCID: PMC7187348 DOI: 10.1111/cmi.13161] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 10/29/2019] [Accepted: 11/14/2019] [Indexed: 01/05/2023]
Abstract
Human immunodeficiency virus (HIV) uses the ESCRT (endosomal sorting complexes required for transport) protein pathway to bud from infected cells. Despite the roles of ESCRT-I and -III in HIV budding being firmly established, participation of ESCRT-II in this process has been controversial. EAP45 is a critical component of ESCRT-II. Previously, we utilised a CRISPR-Cas9 EAP45 knockout cell line to assess the involvement of ESCRT-II in HIV replication. We demonstrated that the absence of ESCRT-II impairs HIV budding. Here, we show that virus spread is also defective in physiologically relevant CRISPR/Cas9 EAP45 knockout T cells. We further show reappearance of efficient budding by re-introduction of EAP45 expression into EAP45 knockout cells. Using expression of selected mutants of EAP45, we dissect the domain requirement responsible for this function. Our data show at the steady state that rescue of budding is only observed in the context of a Gag/Pol, but not a Gag expressor, indicating that the size of cargo determines the usage of ESCRT-II. EAP45 acts through the YPXL-ALIX pathway as partial rescue is achieved in a PTAP but not a YPXL mutant virus. Our study clarifies the role of ESCRT-II in the late stages of HIV replication and reinforces the notion that ESCRT-II plays an integral part during this process as it does in sorting ubiquitinated cargos and in cytokinesis.
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Affiliation(s)
- Bo Meng
- Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK
| | - Natasha C Y Ip
- Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK
| | - Truus E M Abbink
- Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK
| | - Julia C Kenyon
- Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK.,Department of Microbiology and Immunology, National University of Singapore, Singapore.,Homerton College, Cambridge, UK
| | - Andrew M L Lever
- Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK.,Department of Medicine, National University of Singapore, Singapore
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15
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Han Z, Dash S, Sagum CA, Ruthel G, Jaladanki CK, Berry CT, Schwoerer MP, Harty NM, Freedman BD, Bedford MT, Fan H, Sidhu SS, Sudol M, Shtanko O, Harty RN. Modular mimicry and engagement of the Hippo pathway by Marburg virus VP40: Implications for filovirus biology and budding. PLoS Pathog 2020; 16:e1008231. [PMID: 31905227 PMCID: PMC6977764 DOI: 10.1371/journal.ppat.1008231] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 01/23/2020] [Accepted: 11/21/2019] [Indexed: 01/16/2023] Open
Abstract
Ebola (EBOV) and Marburg (MARV) are members of the Filoviridae family, which continue to emerge and cause sporadic outbreaks of hemorrhagic fever with high mortality rates. Filoviruses utilize their VP40 matrix protein to drive virion assembly and budding, in part, by recruitment of specific WW-domain-bearing host proteins via its conserved PPxY Late (L) domain motif. Here, we screened an array of 115 mammalian, bacterially expressed and purified WW-domains using a PPxY-containing peptide from MARV VP40 (mVP40) to identify novel host interactors. Using this unbiased approach, we identified Yes Associated Protein (YAP) and Transcriptional co-Activator with PDZ-binding motif (TAZ) as novel mVP40 PPxY interactors. YAP and TAZ function as downstream transcriptional effectors of the Hippo signaling pathway that regulates cell proliferation, migration and apoptosis. We demonstrate that ectopic expression of YAP or TAZ along with mVP40 leads to significant inhibition of budding of mVP40 VLPs in a WW-domain/PPxY dependent manner. Moreover, YAP colocalized with mVP40 in the cytoplasm, and inhibition of mVP40 VLP budding was more pronounced when YAP was localized predominantly in the cytoplasm rather than in the nucleus. A key regulator of YAP nuclear/cytoplasmic localization and function is angiomotin (Amot); a multi-PPxY containing protein that strongly interacts with YAP WW-domains. Interestingly, we found that expression of PPxY-containing Amot rescued mVP40 VLP egress from either YAP- or TAZ-mediated inhibition in a PPxY-dependent manner. Importantly, using a stable Amot-knockdown cell line, we found that expression of Amot was critical for efficient egress of mVP40 VLPs as well as egress and spread of authentic MARV in infected cell cultures. In sum, we identified novel negative (YAP/TAZ) and positive (Amot) regulators of MARV VP40-mediated egress, that likely function in part, via competition between host and viral PPxY motifs binding to modular host WW-domains. These findings not only impact our mechanistic understanding of virus budding and spread, but also may impact the development of new antiviral strategies. By screening an array of 115 mammalian WW-domains with the PPxY motif from MARV VP40 (mVP40), we identified YAP1 and TAZ, transcriptional effectors of the Hippo pathway, as mVP40 interactors, and demonstrated that ectopically expressed YAP1 or TAZ inhibited budding of mVP40 virus-like particles (VLPs) in a WW-domain/PPxY dependent manner. Angiomotin (Amot), a multi-PPxY containing regulator of YAP1 nuclear/cytoplasmic localization and function, rescued mVP40 VLP egress from either YAP1- or TAZ-mediated inhibition in a PPxY-dependent manner. Indeed, endogenous Amot expression was critical for egress of mVP40 VLPs and authentic MARV. In sum, we have revealed a link between the Hippo pathway and filovirus egress by identifying negative (YAP/TAZ) and positive (Amot) regulators of MARV VP40-mediated egress.
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Affiliation(s)
- Ziying Han
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Shantoshini Dash
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Cari A. Sagum
- Department of Epigenetics & Molecular Carcinogenesis, M.D. Anderson Cancer Center, University of Texas, Smithville, Texas, United States of America
| | - Gordon Ruthel
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Chaitanya K. Jaladanki
- Department of Physiology and Mechanobiology Institute at National University of Singapore, Institute for Molecular and Cell Biology, IMCB, and Bioinformatics Institute, Agency for Science, Technology and Research (A*STAR), Singapore
| | - Corbett T. Berry
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Michael P. Schwoerer
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Nina M. Harty
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Bruce D. Freedman
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Mark T. Bedford
- Department of Epigenetics & Molecular Carcinogenesis, M.D. Anderson Cancer Center, University of Texas, Smithville, Texas, United States of America
| | - Hao Fan
- Department of Physiology and Mechanobiology Institute at National University of Singapore, Institute for Molecular and Cell Biology, IMCB, and Bioinformatics Institute, Agency for Science, Technology and Research (A*STAR), Singapore
| | - Sachdev S. Sidhu
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Marius Sudol
- Department of Physiology and Mechanobiology Institute at National University of Singapore, Institute for Molecular and Cell Biology, IMCB, and Bioinformatics Institute, Agency for Science, Technology and Research (A*STAR), Singapore
| | - Olena Shtanko
- Texas Biomedical Research Institute, San Antonio, Texas, United States of America
| | - Ronald N. Harty
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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16
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Hoffman HK, Fernandez MV, Groves NS, Freed EO, van Engelenburg SB. Genomic tagging of endogenous human ESCRT-I complex preserves ESCRT-mediated membrane-remodeling functions. J Biol Chem 2019; 294:16266-16281. [PMID: 31519756 PMCID: PMC6827313 DOI: 10.1074/jbc.ra119.009372] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 09/10/2019] [Indexed: 12/19/2022] Open
Abstract
The endosomal sorting complexes required for transport (ESCRT) machinery drives membrane scission for diverse cellular functions that require budding away from the cytosol, including cell division and transmembrane receptor trafficking and degradation. The ESCRT machinery is also hijacked by retroviruses, such as HIV-1, to release virions from infected cells. The crucial roles of the ESCRTs in cellular physiology and viral disease make it imperative to understand the membrane scission mechanism. Current methodological limitations, namely artifacts caused by overexpression of ESCRT subunits, obstruct our understanding of the spatiotemporal organization of the endogenous human ESCRT machinery. Here, we used CRISPR/Cas9-mediated knock-in to tag the critical ESCRT-I component tumor susceptibility 101 (Tsg101) with GFP at its native locus in two widely used human cell types, HeLa epithelial cells and Jurkat T cells. We validated this approach by assessing the function of these knock-in cell lines in cytokinesis, receptor degradation, and virus budding. Using this probe, we measured the incorporation of endogenous Tsg101 in released HIV-1 particles, supporting the notion that the ESCRT machinery initiates virus abscission by scaffolding early-acting ESCRT-I within the head of the budding virus. We anticipate that these validated cell lines will be a valuable tool for interrogating dynamics of the native human ESCRT machinery.
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Affiliation(s)
- Huxley K Hoffman
- Molecular and Cellular Biophysics Program, Department of Biological Sciences, University of Denver, Denver, Colorado 80210
| | - Melissa V Fernandez
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, Center for Cancer Research, NCI-Frederick, National Institutes of Health, Frederick, Maryland 21702
| | - Nicholas S Groves
- Molecular and Cellular Biophysics Program, Department of Biological Sciences, University of Denver, Denver, Colorado 80210
| | - Eric O Freed
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, Center for Cancer Research, NCI-Frederick, National Institutes of Health, Frederick, Maryland 21702
| | - Schuyler B van Engelenburg
- Molecular and Cellular Biophysics Program, Department of Biological Sciences, University of Denver, Denver, Colorado 80210
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17
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Watanabe SM, Medina GN, Eastep GN, Ghanam RH, Vlach J, Saad JS, Carter CA. The matrix domain of the Gag protein from avian sarcoma virus contains a PI(4,5)P 2-binding site that targets Gag to the cell periphery. J Biol Chem 2018; 293:18841-18853. [PMID: 30309982 DOI: 10.1074/jbc.ra118.003947] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2018] [Revised: 09/28/2018] [Indexed: 01/08/2023] Open
Abstract
The Gag protein of avian sarcoma virus (ASV) lacks an N-myristoyl (myr) group, but contains structural domains similar to those of HIV-1 Gag. Similarly to HIV-1, ASV Gag accumulates on the plasma membrane (PM) before egress; however, it is unclear whether the phospholipid PI(4,5)P2 binds directly to the matrix (MA) domain of ASV Gag, as is the case for HIV-1 Gag. Moreover, the role of PI(4,5)P2 in ASV Gag localization and budding has been controversial. Here, we report that substitution of residues that define the PI(4,5)P2-binding site in the ASV MA domain (reported in an accompanying paper) interfere with Gag localization to the cell periphery and inhibit the production of virus-like particles (VLPs). We show that co-expression of Sprouty2 (Spry2) or the pleckstrin homology domain of phospholipase Cδ (PH-PLC), two proteins that bind PI(4,5)P2, affects ASV Gag trafficking to the PM and budding. Replacement of the N-terminal 32 residues of HIV-1 MA, which encode its N-terminal myr signal and its PI(4,5)P2-binding site, with the structurally equivalent N-terminal 24 residues of ASV MA created a chimera that localized at the PM and produced VLPs. In contrast, the homologous PI(4,5)P2-binding signal in ASV MA could target HIV-1 Gag to the PM when substituted, but did not support budding. Collectively, these findings reveal a basic patch in both ASV and HIV-1 Gag capable of mediating PM binding and budding for ASV but not for HIV-1 Gag. We conclude that PI(4,5)P2 is a strong determinant of ASV Gag targeting to the PM and budding.
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Affiliation(s)
- Susan M Watanabe
- From the Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York 11794 and
| | - Gisselle N Medina
- From the Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York 11794 and
| | - Gunnar N Eastep
- the Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Ruba H Ghanam
- the Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Jiri Vlach
- the Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Jamil S Saad
- the Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Carol A Carter
- From the Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York 11794 and
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18
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Ubiquitin Ligase WWP1 Interacts with Ebola Virus VP40 To Regulate Egress. J Virol 2017; 91:JVI.00812-17. [PMID: 28768865 DOI: 10.1128/jvi.00812-17] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 07/24/2017] [Indexed: 01/05/2023] Open
Abstract
Ebola virus (EBOV) is a member of the Filoviridae family and the cause of hemorrhagic fever outbreaks. The EBOV VP40 (eVP40) matrix protein is the main driving force for virion assembly and budding. Indeed, expression of eVP40 alone in mammalian cells results in the formation and budding of virus-like particles (VLPs) which mimic the budding process and morphology of authentic, infectious EBOV. To complete the budding process, eVP40 utilizes its PPXY L-domain motif to recruit a specific subset of host proteins containing one or more modular WW domains that then function to facilitate efficient production and release of eVP40 VLPs. In this report, we identified additional host WW-domain interactors by screening for potential interactions between mammalian proteins possessing one or more WW domains and WT or PPXY mutant peptides of eVP40. We identified the HECT family E3 ubiquitin ligase WWP1 and all four of its WW domains as strong interactors with the PPXY motif of eVP40. The eVP40-WWP1 interaction was confirmed by both peptide pulldown and coimmunoprecipitation assays, which also demonstrated that modular WW domain 1 of WWP1 was most critical for binding to eVP40. Importantly, the eVP40-WWP1 interaction was found to be biologically relevant for VLP budding since (i) small interfering RNA (siRNA) knockdown of endogenous WWP1 resulted in inhibition of eVP40 VLP egress, (ii) coexpression of WWP1 and eVP40 resulted in ubiquitination of eVP40 and a subsequent increase in eVP40 VLP egress, and (iii) an enzymatically inactive mutant of WWP1 (C890A) did not ubiquitinate eVP40 or enhance eVP40 VLP egress. Last, our data show that ubiquitination of eVP40 by WWP1 enhances egress of VLPs and concomitantly decreases cellular levels of higher-molecular-weight oligomers of eVP40. In sum, these findings contribute to our fundamental understanding of the functional interplay between host E3 ligases, ubiquitination, and regulation of EBOV VP40-mediated egress.IMPORTANCE Ebola virus (EBOV) is a high-priority, emerging human pathogen that can cause severe outbreaks of hemorrhagic fever with high mortality rates. As there are currently no approved vaccines or treatments for EBOV, a better understanding of the biology and functions of EBOV-host interactions that promote or inhibit viral budding is warranted. Here, we describe a physical and functional interaction between EBOV VP40 (eVP40) and WWP1, a host E3 ubiquitin ligase that ubiquitinates VP40 and regulates VLP egress. This viral PPXY-host WW domain-mediated interaction represents a potential new target for host-oriented inhibitors of EBOV egress.
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19
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Growing functions of the ESCRT machinery in cell biology and viral replication. Biochem Soc Trans 2017; 45:613-634. [PMID: 28620025 DOI: 10.1042/bst20160479] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 02/17/2017] [Accepted: 02/21/2017] [Indexed: 01/31/2023]
Abstract
The vast expansion in recent years of the cellular processes promoted by the endosomal sorting complex required for transport (ESCRT) machinery has reinforced its identity as a modular system that uses multiple adaptors to recruit the core membrane remodelling activity at different intracellular sites and facilitate membrane scission. Functional connections to processes such as the aurora B-dependent abscission checkpoint also highlight the importance of the spatiotemporal regulation of the ESCRT machinery. Here, we summarise the role of ESCRTs in viral budding, and what we have learned about the ESCRT pathway from studying this process. These advances are discussed in the context of areas of cell biology that have been transformed by research in the ESCRT field, including cytokinetic abscission, nuclear envelope resealing and plasma membrane repair.
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20
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ITCH E3 Ubiquitin Ligase Interacts with Ebola Virus VP40 To Regulate Budding. J Virol 2016; 90:9163-71. [PMID: 27489272 DOI: 10.1128/jvi.01078-16] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 07/25/2016] [Indexed: 01/27/2023] Open
Abstract
UNLABELLED Ebola virus (EBOV) and Marburg virus (MARV) belong to the Filoviridae family and can cause outbreaks of severe hemorrhagic fever, with high mortality rates in humans. The EBOV VP40 (eVP40) and MARV VP40 (mVP40) matrix proteins play a central role in virion assembly and egress, such that independent expression of VP40 leads to the production and egress of virus-like particles (VLPs) that accurately mimic the budding of infectious virus. Late (L) budding domains of eVP40 recruit host proteins (e.g., Tsg101, Nedd4, and Alix) that are important for efficient virus egress and spread. For example, the PPxY-type L domain of eVP40 and mVP40 recruits the host Nedd4 E3 ubiquitin ligase via its WW domains to facilitate budding. Here we sought to identify additional WW domain host interactors and demonstrate that the PPxY L domain motif of eVP40 interacts specifically with the WW domain of the host E3 ubiquitin ligase ITCH. ITCH, like Nedd4, is a member of the HECT class of E3 ubiquitin ligases, and the resultant physical and functional interaction with eVP40 facilitates VLP and virus budding. Identification of this novel eVP40 interactor highlights the functional interplay between cellular E3 ligases, ubiquitination, and regulation of VP40-mediated egress. IMPORTANCE The unprecedented magnitude and scope of the recent 2014-2015 EBOV outbreak in West Africa and its emergence here in the United States and other countries underscore the critical need for a better understanding of the biology and pathogenesis of this emerging pathogen. We have identified a novel and functional EBOV VP40 interactor, ITCH, that regulates VP40-mediated egress. This virus-host interaction may represent a new target for our previously identified small-molecule inhibitors of virus egress.
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21
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ESCRT Requirements for Murine Leukemia Virus Release. Viruses 2016; 8:103. [PMID: 27096867 PMCID: PMC4848597 DOI: 10.3390/v8040103] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 04/01/2016] [Accepted: 04/13/2016] [Indexed: 12/20/2022] Open
Abstract
The Murine Leukemia Virus (MLV) is a gammaretrovirus that hijack host components of the endosomal sorting complex required for transport (ESCRT) for budding. To determine the minimal requirements for ESCRT factors in MLV viral and viral-like particles (VLP) release, an siRNA knockdown screen of ESCRT(-associated) proteins was performed in MLV-producing human cells. We found that MLV VLPs and virions primarily engage the ESCRT-I factor Tsg101 and marginally the ESCRT-associated adaptors Nedd4-1 and Alix to enter the ESCRT pathway. Conversely, the inactivation of ESCRT-II had no impact on VLP and virion egress. By analyzing the effects of individual ESCRT-III knockdowns, VLP and virion release was profoundly inhibited in CHMP2A- and CHMP4B-knockdown cells. In contrast, neither the CHMP2B and CHMP4A isoforms nor CHMP3, CHMP5, and CHMP6 were found to be essential. In case of CHMP1, we unexpectedly observed that the CHMP1A isoform was specifically required for virus budding, but dispensable for VLP release. Hence, MLV utilizes only a subset of ESCRT factors, and viral and viral-like particles differ in ESCRT-III factor requirements.
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22
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Meng B, Ip NCY, Prestwood LJ, Abbink TEM, Lever AML. Evidence that the endosomal sorting complex required for transport-II (ESCRT-II) is required for efficient human immunodeficiency virus-1 (HIV-1) production. Retrovirology 2015; 12:72. [PMID: 26268989 PMCID: PMC4535389 DOI: 10.1186/s12977-015-0197-x] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 07/31/2015] [Indexed: 11/17/2022] Open
Abstract
Background Egress of a number of different virus species from infected cells depends on proteins of the endosomal sorting complexes required for transport (ESCRT) pathway. HIV has also hijacked this system to bud viruses outward from the cell surface. How ESCRT-I activates ESCRT-III in this process remains unclear with conflicting published evidence for the requirement of ESCRT-II which fulfils this role in other systems. We investigated the role of ESCRT-II using knockdown mediated by siRNA and shRNA, mutants which prevent ESCRT-I/ESCRT-II interaction and a CRISPR/Cas9 EAP45 knockout cell line. Results Depletion or elimination of ESCRT-II components from an HIV infected cell produces two distinct effects. The overall production of HIV-1 Gag is reduced leading to a diminished amount of intracellular virion protein. In addition depletion of ESCRT-II produces an effect similar to that seen when ESCRT-I and -III components are depleted, that of a delayed Gag p26 to p24 +p2 cleavage associated with a reduction in export of virion particles and a visible reduction in budding efficiency in virus producing cells. Mutants that interfere with ESCRT-I interacting with ESCRT-II similarly reduce virus export. The export defect is independent of the decrease in overall Gag production. Using a mutant virus which cannot use the ALIX mediated export pathway exacerbates the decrease in virus export seen when ESCRT-II is depleted. ESCRT-II knockdown does not lead to complete elimination of virus release suggesting that the late domain role of ESCRT-II is required for optimal efficiency of viral budding but that there are additional pathways that the virus can employ to facilitate this. Conclusion ESCRT-II contributes to efficient HIV virion production and export by more than one pathway; both by a transcriptional or post transcriptional mechanism and also by facilitating efficient virus export from the cell through interactions with other ESCRT components. Electronic supplementary material The online version of this article (doi:10.1186/s12977-015-0197-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Bo Meng
- Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK.
| | - Natasha C Y Ip
- Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK.
| | - Liam J Prestwood
- Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK.
| | - Truus E M Abbink
- Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK. .,Centre for Childhood White Matter Disorders, VU University Medical Centre, Amsterdam, The Netherlands.
| | - Andrew M L Lever
- Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK.
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23
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Stieler JT, Prange R. Involvement of ESCRT-II in hepatitis B virus morphogenesis. PLoS One 2014; 9:e91279. [PMID: 24614091 PMCID: PMC3948859 DOI: 10.1371/journal.pone.0091279] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Accepted: 02/10/2014] [Indexed: 01/20/2023] Open
Abstract
The hepatitis B virus (HBV) is an enveloped DNA virus that replicates via reverse transcription of its pregenomic RNA (pgRNA). Budding of HBV is supposed to occur at intracellular membranes and requires scission functions of the endosomal sorting complex required for transport (ESCRT) provided by ESCRT-III and VPS4. Here, we have investigated the impact of the upstream-acting ESCRT-I and ESCRT-II complexes in HBV morphogenesis. RNA interference knockdown of the ESCRT-I subunits TSG101 and VPS28 did not block, but rather stimulate virus release. In contrast, RNAi-mediated depletion of the ESCRT-II components EAP20, EAP30 and EAP45 greatly reduced virus egress. By analyzing different steps of the HBV maturation pathway, we find that the knockdown of ESCRT-II not only inhibited the production and/or release of enveloped virions, but also impaired intracellular nucleocapsid formation. Transcription/translation studies revealed that the depletion of ESCRT-II neither affected the synthesis and nuclear export of HBV-specific RNAs nor the expression of the viral core and envelope proteins. Moreover, the absence of ESCRT-II had no effects on the assembly capability and integrity of HBV core/capsids. However, the level of encapsidated pgRNA was significantly reduced in ESCRT-II-depleted cells, implicating that ESCRT-II directs steps accompanying the formation of replication-competent nucleocapsids, like e.g. assisting in RNA trafficking and encapsidation. In support of this, the capsid protein was found to interact and colocalize with ESCRT-II subunits in virus-producing cells. Together, these results indicate an essential role for ESCRT-II in the HBV life cycle and suggest that ESCRT-II functions prior to the final HBV budding reaction.
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Affiliation(s)
- Jens T. Stieler
- Department of Medical Microbiology and Hygiene, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Reinhild Prange
- Department of Medical Microbiology and Hygiene, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
- * E-mail:
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Nagashima S, Takahashi M, Jirintai S, Tanggis, Kobayashi T, Nishizawa T, Okamoto H. The membrane on the surface of hepatitis E virus particles is derived from the intracellular membrane and contains trans-Golgi network protein 2. Arch Virol 2013; 159:979-91. [PMID: 24221250 DOI: 10.1007/s00705-013-1912-3] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Accepted: 10/28/2013] [Indexed: 12/13/2022]
Abstract
Our previous studies demonstrated that hepatitis E virus (HEV) requires the multivesicular body (MVB) pathway to release virus particles, suggesting that HEV utilizes the cellular ESCRT machinery in the cytoplasm, not at the cell surface, to be released from infected cells. In this study, we generated a murine monoclonal antibody (mAb) against the membrane-associated HEV particles to examine whether the membrane is derived from intracellular vesicles or the cell surface. An established mAb, TA1708, was found to capture the membrane-associated HEV particles, but not the membrane-dissociated particles or fecal HEV, in an immunocapture RT-PCR assay. Furthermore, digitonin treatment confirmed that the membrane on the surface of cell-culture-generated HEV particles was a lipid membrane. Double immunofluorescence staining revealed that mAb TA1708 specifically recognizes trans-Golgi network protein 2 (TGOLN2), an intracellular antigen derived from the trans-Golgi network. Supporting these findings, HEV particles with lipid membranes and ORF3 proteins on their surface were found abundantly in the lysates of HEV-infected cells. These results indicate that HEV forms membrane-associated particles in the cytoplasm, most likely by budding into intracellular vesicles, and that the released HEV particles with a lipid membrane retain the antigenicity of TGOLN2 on their surface.
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Affiliation(s)
- Shigeo Nagashima
- Division of Virology, Department of Infection and Immunity, Jichi Medical University School of Medicine, 3311-1 Yakushiji, Shimotsuke, Tochigi, 329-0498, Japan
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25
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Abstract
The endosomal sorting complexes required for transport (ESCRT) pathway was initially defined in yeast genetic screens that identified the factors necessary to sort membrane proteins into intraluminal endosomal vesicles. Subsequent studies have revealed that the mammalian ESCRT pathway also functions in a series of other key cellular processes, including formation of extracellular microvesicles, enveloped virus budding, and the abscission stage of cytokinesis. The core ESCRT machinery comprises Bro1 family proteins and ESCRT-I, ESCRT-II, ESCRT-III, and VPS4 complexes. Site-specific adaptors recruit these soluble factors to assemble on different cellular membranes, where they carry out membrane fission reactions. ESCRT-III proteins form filaments that draw membranes together from the cytoplasmic face, and mechanistic models have been advanced to explain how ESCRT-III filaments and the VPS4 ATPase can work together to catalyze membrane fission.
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Affiliation(s)
- John McCullough
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah 84112-5650, USA
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Ghoujal B, Milev MP, Ajamian L, Abel K, Mouland AJ. ESCRT-II's involvement in HIV-1 genomic RNA trafficking and assembly. Biol Cell 2012; 104:706-21. [PMID: 22978549 DOI: 10.1111/boc.201200021] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Accepted: 09/06/2012] [Indexed: 11/26/2022]
Abstract
BACKGROUND INFORMATION Several host proteins play crucial roles in the HIV-1 replication cycle. The endosomal sorting complex required for transport (ESCRT) exemplifies a large, multi-component host machinery that is required by HIV-1 for viral budding. ESCRT promotes the inward budding of vesicles from the membranes of late endosomes to generate multi-vesicular bodies. However, HIV-1 co-opts the ESCRT to enable outwards budding of virus particles from the plasma membrane, a phenomenon that is topologically similar to multi-vesicular body biogenesis. A role for ESCRTII in mRNA trafficking has been established in Drosophila in which the ESCRT-II components, Vps22 and Vps36, promote the localisation of the bicoid mRNA in the fertilised egg. This is achieved via specific interactions with the Staufen protein. In this work, we investigated a possible implication of ESCRT-II in the HIV-1 replication cycle. RESULTS Co-immunoprecipitation analyses and live cell tri-molecular fluorescence complementation assays revealed that interactions between EAP30 and Gag and another between EAP30 and Staufen1 occur in mammalian cells. We then depleted EAP30 (the orthologue for Vps22) by siRNA to target ESCRT-II in HIV-1 expressing cells. This treatment disrupted ESCRT-II function and leads to the degradation of the two other ESCRT-II complex proteins, EAP45 and EAP20, as well as the associated Rab7-interacting lysosomal protein. The depletion of EAP30 led to dramatically reduced viral structural protein Gag and virus production levels, without any effect on viral RNA levels. On the contrary, the overexpression of EAP30 led to a several-fold increase in virus production. Unexpec-tedly, siRNA-mediated depletion of EAP30 led to a block to HIV-1 genomic RNA trafficking and resulted in the accumulation of genomic RNA in the nucleus and juxtanuclear domains. CONCLUSIONS Our data provide the first evidence that the Staufen1-ESCRT-II interaction is evolutionarily conserved from lower to higher eukaryotes and reveal a novel role for EAP30 in the control of HIV-1 RNA trafficking and gene expression.
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Affiliation(s)
- Bashar Ghoujal
- HIV-1 RNA Trafficking Laboratory, Lady Davis Institute at the Jewish General Hospital and the Department of Medicine, Division of Experimental Medicine, McGill University, Montréal, Québec H3T 1E2, Canada
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HIV Assembly and Budding: Ca(2+) Signaling and Non-ESCRT Proteins Set the Stage. Mol Biol Int 2012; 2012:851670. [PMID: 22761998 PMCID: PMC3384956 DOI: 10.1155/2012/851670] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Accepted: 03/26/2012] [Indexed: 12/16/2022] Open
Abstract
More than a decade has elapsed since the link between the endosomal sorting complex required for transport (ESCRT) machinery and HIV-1 protein trafficking and budding was first identified. L domains in HIV-1 Gag mediate recruitment of ESCRT which function in bud abscission releasing the viral particle from the host cell. Beyond virus budding, the ESCRT machinery is also involved in the endocytic pathway, cytokinesis, and autophagy. In the past few years, the number of non-ESCRT host proteins shown to be required in the assembly process has also grown. In this paper, we highlight the role of recently identified cellular factors that link ESCRT machinery to calcium signaling machinery and we suggest that this liaison contributes to setting the stage for productive ESCRT recruitment and mediation of abscission. Parallel paradigms for non-ESCRT roles in virus budding and cytokinesis will be discussed.
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Budding of Enveloped Viruses: Interferon-Induced ISG15-Antivirus Mechanisms Targeting the Release Process. Adv Virol 2012; 2012:532723. [PMID: 22666250 PMCID: PMC3362814 DOI: 10.1155/2012/532723] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Accepted: 03/12/2012] [Indexed: 11/17/2022] Open
Abstract
Pathogenic strains of viruses that infect humans are encapsulated in membranes derived from the host cell in which they infect. After replication, these viruses are released by a budding process that requires cell/viral membrane scission. As such, this represents a natural target for innate immunity mechanisms to interdict enveloped virus spread and recent advances in this field will be the subject of this paper.
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Ehrlich LS, Medina GN, Carter CA. ESCRT machinery potentiates HIV-1 utilization of the PI(4,5)P(2)-PLC-IP3R-Ca(2+) signaling cascade. J Mol Biol 2011; 413:347-58. [PMID: 21875593 PMCID: PMC3193579 DOI: 10.1016/j.jmb.2011.08.038] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Revised: 08/05/2011] [Accepted: 08/16/2011] [Indexed: 01/09/2023]
Abstract
Human immunodeficiency virus type 1 (HIV-1) release efficiency is directed by late (L) domain motifs in the viral structural precursor polyprotein Gag, which serve as links to the ESCRT (endosomal sorting complex required for transport) machinery. Linkage is normally through binding of Tsg101, an ESCRT-1 component, to the P(7)TAP motif in the p6 region of Gag. In its absence, budding is directed by binding of Alix, an ESCRT adaptor protein, to the LY(36)PX(n)L motif in Gag. We recently showed that budding requires activation of the inositol 1,4,5-triphosphate receptor (IP3R), a protein that "gates" Ca(2+) release from intracellular stores, triggers Ca(2+) cell influx and thereby functions as a major regulator of Ca(2+) signaling. In the present study, we determined whether the L domain links Gag to Ca(2+) signaling machinery. Depletion of IP3R and inactivation of phospholipase C (PLC) inhibited budding whether or not Tsg101 was bound to Gag. PLC hydrolysis of phosphatidylinositol-(4,5)-bisphosphate generates inositol (1,4,5)-triphosphate, the ligand that activates IP3R. However, with Tsg101 bound, Gag release was independent of Gq-mediated activation of PLC, and budding was readily enhanced by pharmacological stimulation of PLC. Moreover, IP3R was redistributed to the cell periphery and cytosolic Ca(2+) was elevated, events indicative of induction of Ca(2+) signaling. The results suggest that L domain function, ESCRT machinery and Ca(2+) signaling are linked events in Gag release.
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Affiliation(s)
- Lorna S. Ehrlich
- Dept. of Molecular Genetics & Microbiology, Stony Brook University, Stony Brook, NY 11794-5222, USA
| | - Gisselle N. Medina
- Dept. of Molecular Genetics & Microbiology, Stony Brook University, Stony Brook, NY 11794-5222, USA
| | - Carol A. Carter
- Dept. of Molecular Genetics & Microbiology, Stony Brook University, Stony Brook, NY 11794-5222, USA
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Nagashima S, Takahashi M, Jirintai S, Tanaka T, Nishizawa T, Yasuda J, Okamoto H. Tumour susceptibility gene 101 and the vacuolar protein sorting pathway are required for the release of hepatitis E virions. J Gen Virol 2011; 92:2838-2848. [PMID: 21880841 DOI: 10.1099/vir.0.035378-0] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
We have previously demonstrated that an intact PSAP motif in the ORF3 protein is required for the formation and release of membrane-associated hepatitis E virus (HEV) particles with ORF3 proteins on their surface. In this study, we investigated the direct interaction between the ORF3 protein and tumour susceptibility gene 101 (Tsg101), a cellular factor involved in the budding of viruses containing the P(T/S)AP late-domain, in PLC/PRF/5 cells expressing the wild-type or PSAP-mutated ORF3 protein and Tsg101 by co-immunoprecipitation. Tsg101 bound to wild-type ORF3 protein, but not to the PSAP-inactive ORF3 protein. To examine whether HEV utilizes the multivesicular body (MVB) pathway to release the virus particles, we analysed the efficiency of virion release from cells upon introduction of small interfering RNA (siRNA) against Tsg101 or dominant-negative (DN) mutants of Vps4 (Vps4A and Vps4B). The relative levels of virus particles released from cells depleted of Tsg101 decreased to 6.4 % of those transfected with negative control siRNA. Similarly, virion egress was significantly reduced by the overexpression of DN forms (Vps4AEQ or Vps4BEQ). The relative levels of virus particles released from cells expressing Vps4AEQ and Vps4BEQ were 19.2 and 15.6 %, respectively, while the overexpression of wild-type Vps4A and Vps4B did not alter the levels of virus release. These results indicate that the ORF3 protein interacts with Tsg101 through the PSAP motifs in infected cells, and that Tsg101 and the enzymic activities of Vps4A and Vps4B are involved in HEV release, thus suggesting that HEV requires the MVB pathway for egress of virus particles.
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Affiliation(s)
- Shigeo Nagashima
- Division of Virology, Department of Infection and Immunity, Jichi Medical University School of Medicine, Tochigi-Ken 329-0498, Japan
| | - Masaharu Takahashi
- Division of Virology, Department of Infection and Immunity, Jichi Medical University School of Medicine, Tochigi-Ken 329-0498, Japan
| | - Suljid Jirintai
- Division of Virology, Department of Infection and Immunity, Jichi Medical University School of Medicine, Tochigi-Ken 329-0498, Japan
| | - Toshinori Tanaka
- Division of Virology, Department of Infection and Immunity, Jichi Medical University School of Medicine, Tochigi-Ken 329-0498, Japan
| | - Tsutomu Nishizawa
- Division of Virology, Department of Infection and Immunity, Jichi Medical University School of Medicine, Tochigi-Ken 329-0498, Japan
| | - Jiro Yasuda
- Department of Emerging Infectious Diseases, Institute of Tropical Medicine, Nagasaki University, Nagasaki-Ken 852-8523, Japan
| | - Hiroaki Okamoto
- Division of Virology, Department of Infection and Immunity, Jichi Medical University School of Medicine, Tochigi-Ken 329-0498, Japan
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31
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Abstract
The endosomal-sorting complex required for transport (ESCRT) apparatus has multiple ubiquitin (Ub)-binding domains and participates in a wide variety of cellular processes. Many of these ESCRT-dependent processes are keenly regulated by Ub, which serves as a lysosomal-sorting signal for membrane proteins targeted into multivesicular bodies (MVBs) and which may serve as a mediator of viral budding from the cell surface. Hints that both ESCRTs and Ub work together in the processes such as cytokinesis, transcription and autophagy are beginning to emerge. Here, we explore the relationship between ESCRTs and Ub in MVB sorting and viral budding.
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Affiliation(s)
- S Brookhart Shields
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, IA 52246, USA
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32
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Kuang Z, Seo EJ, Leis J. Mechanism of inhibition of retrovirus release from cells by interferon-induced gene ISG15. J Virol 2011; 85:7153-61. [PMID: 21543490 PMCID: PMC3126601 DOI: 10.1128/jvi.02610-10] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Accepted: 04/28/2011] [Indexed: 11/20/2022] Open
Abstract
Budding of retroviruses from cell membranes requires ubiquitination of Gag and recruitment of cellular proteins involved in endosome sorting, including endosome sorting complex required for transport III (ESCRT-III) protein complex and vacuolar protein sorting 4 (VPS4) and its ATPase. In response to infection, a cellular mechanism has evolved that blocks virus replication early and late in the budding process through expression of interferon-stimulated gene 15 (ISG15), a dimer homologue of ubiquitin. Interferon treatment of DF-1 cells blocks avian sarcoma/leukosis virus release, demonstrating that this mechanism is functional under physiological conditions. The late block to release is caused in part by a loss in interaction between VPS4 and its coactivator protein LIP5, which is required to promote the formation of the ESCRT III-VPS4 double-hexamer complex to activate its ATPase. ISG15 is conjugated to two different LIP5-ESCRT-III-binding charged multivesicular body proteins, CHMP2A and CHMP5. Upon ISGylation of each, interaction with LIP5 is no longer detected. Two other ESCRT-III proteins, CHMP4B and CHMP6, are also conjugated to ISG15. ISGylation of CHMP2A, CHMP4B, and CHMP6 weakens their binding directly to VPS4, thereby facilitating the release of this protein from the membrane into the cytosol. The remaining budding complex fails to release particles from the cell membrane. Introducing a mutant of ISG15 into cells that cannot be conjugated to proteins prevents the ISG15-dependent mechanism from blocking virus release. CHMP5 is the primary switch to initiate the antiviral mechanism, because removal of CHMP5 from cells prevents ISGylation of CHMP2A and CHMP6.
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Affiliation(s)
- Zhizhou Kuang
- Department of Microbiology and Immunology, Feinberg School of Medicine, Northwestern University, Feinberg School of Medicine, Northwestern University, 303 E. Chicago Ave., Chicago, IL 60611.
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Abstract
In their recent publication, Rossman et al. describe how the inherent budding capability of its M2 protein allows influenza A virus to bypass recruitment of the cellular ESCRT machinery enlisted by several other enveloped RNA and DNA viruses, including HIV, Ebola, rabies, herpes simplex type 1 and hepatitis B. Studies from the same laboratory and other laboratories indicate that budding of plasmid-derived virus-like particles can be mediated by the influenza virus hemagglutinin and neuraminidase proteins in the absence of M2. These events are also independent of canonical ESCRT components. Understanding how intrinsic properties of these influenza virus proteins permit ESCRT-independent budding expands our understanding of the budding process itself.
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34
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Malerød L, Pedersen NM, Sem Wegner CE, Lobert VH, Leithe E, Brech A, Rivedal E, Liestøl K, Stenmark H. Cargo-dependent degradation of ESCRT-I as a feedback mechanism to modulate endosomal sorting. Traffic 2011; 12:1211-26. [PMID: 21564451 DOI: 10.1111/j.1600-0854.2011.01220.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Ligand-mediated lysosomal degradation of growth factor receptors, mediated by the endosomal sorting complex required for transport (ESCRT) machinery, is a mechanism that attenuates the cellular response to growth factors. In this article, we present a novel regulatory mechanism that involves ligand-mediated degradation of a key component of the sorting machinery itself. We have investigated the endosomal localization of subunits of the four ESCRTs-Hrs (ESCRT-0), Tsg101 (ESCRT-I), EAP30/Vps22 (ESCRT-II) and charged multivesicular body protein 3/Vps24 (ESCRT-III). All the components were detected on the limiting membrane of multivesicular endosomes (MVEs). Surprisingly, however, Tsg101 and other ESCRT-I subunits were also detected within intraluminal vesicles (ILVs) of MVEs. Tsg101 was sequestered along with cargo during endosomal sorting into ILVs and further degraded in lysosomes. Importantly, ESCRT-mediated downregulation of two distinct cargoes, epidermal growth factor receptor (EGFR) and connexin43, mutually made cells refractory to degradation of the other cargo. Our observations indicate that the degradation of a key ESCRT component along with cargo represents a novel feedback control of endosomal sorting by preventing collateral degradation of cell surface receptors following stimulation of one specific pathway.
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Affiliation(s)
- Lene Malerød
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Montebello, Oslo, Norway
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35
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Abstract
The four ESCRT (endocytic sorting complexes required for transport) complexes (ESCRT-0, -I, -II, and -III) normally operate sequentially in the trafficking of cellular cargo. HIV-1 Gag trafficking and release as virus-like particles (VLPs) require the participation of ESCRTs; however, its use of ESCRTs is selective and nonsequential. Specifically, Gag trafficking to release sites on the plasma membrane does not require ESCRT-0 or -II. It is known that a bypass of ESCRT-0 is achieved by the direct linkage of the ESCRT-I component, Tsg101, to the primary L domain motif (PTAP) in Gag and that bypass of ESCRT-II is achieved by the linkage of Gag to ESCRT-III through the adaptor protein Alix. However, the mechanism by which Gag suppresses the interaction of bound ESCRT-I with ESCRT-II is unknown. Here we show (i) that VLP release requires the steady-state level of Sprouty 2 (Spry2) in COS-1 cells, (ii) that Spry2 binds the ESCRT-II component Eap20, (iii) that binding Eap20 permits Spry2 to disrupt ESCRT-I interaction with ESCRT-II, and (iv) that coexpression of Gag with a Spry2 fragment that binds Eap20 increases VLP release. Spry2 also facilitated release of P7L-Gag (i.e., release in the absence of Tsg101 binding). In this case, rescue required the secondary L domain (YPX(n)L) in HIV-1 Gag that binds Alix and the region in Spry2 that binds Eap20. The results identify Spry2 as a novel cellular factor that facilitates release driven by the primary and secondary HIV-1 Gag L domains.
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36
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Sudol M. From Rous sarcoma virus to plasminogen activator, src oncogene and cancer management. Oncogene 2011; 30:3003-10. [PMID: 21383693 DOI: 10.1038/onc.2011.38] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Plasminogen activator (PLAU) is a serine protease that converts plasminogen to plasmin, a general protease, which promotes fibrinolysis and degradation of extracellular matrix. PLAU was reported in 1970s as one of the robustly induced enzymatic activities in Rous sarcoma virus (RSV)-transformed chicken cells. More than three decades later, with the completion of the sequencing of the chicken genome and the subsequent availability of Affymetrix GeneChip genome arrays, several laboratories have surveyed the transcriptional program affected by the RSV transformation. Interestingly, the PLAU gene was shown to be the most highly upregulated transcript. The induction of PLAU was a transformation-dependent process because viruses with deleted Src gene did not induce the transcription of the PLAU gene. Both Src and PLAU genes are associated with and contribute to the complex phenotype of human cancer. Although the activity and structures of these two enzymes are well characterized, the precise molecular function of these gene products in signaling networks is still not fully understood. Yet, the knowledge of their association with cancer is already translated into the clinical setting. Src kinase inhibitors are being tested in clinical trials of cancer therapy, and PLAU gene and its inhibitor have been included as biomarkers with strong prognostic and therapeutic predictive values. This vignette reviews the history of PLAU and Src discovery, and illuminates the complexity of their relationship, but also points to their emerging impact on public health.
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Affiliation(s)
- M Sudol
- Laboratory of Signal Transduction and Proteomic Profiling, Weis Center for Research, Geisinger Clinic, Danville, PA 17822-2608, USA.
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37
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Budding capability of the influenza virus neuraminidase can be modulated by tetherin. J Virol 2011; 85:2480-91. [PMID: 21209114 DOI: 10.1128/jvi.02188-10] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
We have determined that, in addition to its receptor-destroying activity, the influenza virus neuraminidase is capable of efficiently forming virus-like particles (VLPs) when expressed individually from plasmid DNA. This observation applies to both human subtypes of neuraminidase, N1 and N2. However, it is not found with every strain of influenza virus. Through gain-of-function and loss-of-function analyses, a critical determinant within the neuraminidase ectodomain was identified that contributes to VLP formation but is not sufficient to accomplish release of plasmid-derived VLPs. This sequence lies on the plasma membrane-proximal side of the neuraminidase globular head. Most importantly, we demonstrate that the antiviral restriction factor tetherin plays a role in determining the strain-specific limitations of release competency. If tetherin is counteracted by small interfering RNA knockdown or expression of the HIV anti-tetherin factor vpu, budding and release capability is bestowed upon an otherwise budding-deficient neuraminidase. These data suggest that budding-competent neuraminidase proteins possess an as-yet-unidentified means of counteracting the antiviral restriction factor tetherin and identify a novel way in which the influenza virus neuraminidase can contribute to virus release.
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Bimolecular Complementation to Visualize Filovirus VP40-Host Complexes in Live Mammalian Cells: Toward the Identification of Budding Inhibitors. Adv Virol 2011; 2011. [PMID: 22102845 PMCID: PMC3217271 DOI: 10.1155/2011/341816] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Virus-host interactions play key roles in promoting efficient egress of many RNA viruses, including Ebola virus (EBOV or “e”) and Marburg virus (MARV or “m”). Late- (L-) domains conserved in viral matrix proteins recruit specific host proteins, such as Tsg101 and Nedd4, to facilitate the budding process. These interactions serve as attractive targets for the development of broad-spectrum budding inhibitors. A major gap still exists in our understanding of the mechanism of filovirus budding due to the difficulty in detecting virus-host complexes and mapping their trafficking patterns in the natural environment of the cell. To address this gap, we used a bimolecular complementation (BiMC) approach to detect, localize, and follow the trafficking patterns of eVP40-Tsg101 complexes in live mammalian cells. In addition, we used the BiMC approach along with a VLP budding assay to test small molecule inhibitors identified by in silico screening for their ability to block eVP40 PTAP-mediated interactions with Tsg101 and subsequent budding of eVP40 VLPs. We demonstrated the potential broad spectrum activity of a lead candidate inhibitor by demonstrating its ability to block PTAP-dependent binding of HIV-1 Gag to Tsg101 and subsequent egress of HIV-1 Gag VLPs.
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39
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Abstract
Components of the ESCRT (endosomal sorting complex required for transport) machinery mediate endosomal sorting of ubiquitinated membrane proteins. They are key regulators of biological processes important for cell growth and survival, such as growth-factor-mediated signalling and cytokinesis. In addition, enveloped viruses, such as HIV-1, hijack and utilize the ESCRTs for budding during virus release and infection. Obviously, the ESCRT-facilitated pathways require tight regulation, which is partly mediated by a group of interacting proteins, for which our knowledge is growing. In this review we discuss the different ESCRT-modulating proteins and how they influence ESCRT-dependent processes, for example, by acting as positive or negative regulators or by providing temporal and spatial control. A number of the interactors influence the classical ESCRT-mediated process of endosomal cargo sorting, for example, by modulating the interaction between ubiquitinated cargo and the ESCRTs. Certain accessory proteins have been implicated in regulating the activity or steady-state expression levels of the ESCRT components, whereas other interactors control the cellular localization of the ESCRTs, for example, by inducing shuttling between cytosol and nucleus or endosomes. In conclusion, the discovery of novel interactors has and will extend our knowledge of the biological roles of ESCRTs.
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The interferon-induced gene ISG15 blocks retrovirus release from cells late in the budding process. J Virol 2010; 84:4725-36. [PMID: 20164219 DOI: 10.1128/jvi.02478-09] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The release of retroviruses from cells requires ubiquitination of Gag and recruitment of cellular proteins involved in endosome sorting, including the ESCRT-III proteins and the Vps4 ATPase. In response to infection, cells have evolved an interferon-induced mechanism to block virus replication through expression of the interferon-stimulated gene 15 (ISG15), a dimer homologue of ubiquitin, which interferes with ubiquitin pathways in cells. Previously, it has been reported that ISG15 expression inhibited the E3 ubiquitin ligase, Nedd4, and prevented association of the ESCRT-I protein Tsg101 with human immunodeficiency virus type 1 (HIV-1) Gag. The budding of avian sarcoma leukosis virus and HIV-1 Gag virus-like particles containing L-domain mutations can be rescued by fusion to ESCRT proteins, which cause entry into the budding pathway beyond these early steps. The release of these fusions from cells was susceptible to inhibition by ISG15, indicating that there was a block late in the budding process. We now demonstrate that the Vps4 protein does not associate with the avian sarcoma leukosis virus or the HIV-1 budding complexes when ISG15 is expressed. This is caused by a loss in interaction between Vps4 with its coactivator protein LIP5 needed to promote the formation of the ESCRT-III-Vps4 double-hexamer complex required for membrane scission and virus release. The inability of LIP5 to interact with Vps4 is the probable result of ISG15 conjugation to the ESCRT-III protein, CHMP5, which regulates the availability of LIP5. Thus, there appear to be multiple levels of ISG15-induced inhibition acting at different stages of the virus release process.
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41
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Corless L, Crump CM, Griffin SDC, Harris M. Vps4 and the ESCRT-III complex are required for the release of infectious hepatitis C virus particles. J Gen Virol 2010; 91:362-72. [PMID: 19828764 PMCID: PMC7615705 DOI: 10.1099/vir.0.017285-0] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The mechanisms by which infectious hepatitis C virus (HCV) particles are assembled and released from infected cells remain poorly characterized. In this regard, many other enveloped viruses, notably human immunodeficiency virus type 1, have been shown to utilize the host vacuolar protein sorting machinery (also known as the endosomal sorting complex required for transport; ESCRT) to traffic through the cell and effect the membrane rearrangements required for the formation of enveloped particles. We postulated that this might also apply to HCV. To test this hypothesis, we established a method of conditional virus-like particle assembly involving trans-complementation of an envelope-deleted JFH-1 genome using plasmid transfection. This system reliably produced virus particles that were infectious and could be enumerated easily by focus-forming assay in Huh7 cells. Following co-transfection with plasmids expressing various dominant-negative forms of either components of the ESCRT-III complex or Vps4 (the AAA ATPase that recycles the ESCRT complexes), a reduction in particle production was seen. No significant effect was observed after co-transfection of dominant-negative ESCRT-I or Alix, an ESCRT associated protein. Dominant-negative Vps4 or ESCRT-III components had no effect on either virus genome replication or the accumulation of intracellular infectious particles. These data were confirmed using cell culture infectious HCV and we conclude that HCV requires late components of the ESCRT pathway for release of infectious virus particles.
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Affiliation(s)
- Lynsey Corless
- Institute of Molecular and Cellular Biology and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, West Yorkshire, UK
| | - Colin M. Crump
- Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
| | - Stephen D. C. Griffin
- Institute of Molecular and Cellular Biology and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, West Yorkshire, UK
| | - Mark Harris
- Institute of Molecular and Cellular Biology and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, West Yorkshire, UK
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Abstract
In mammalian cells, there is evidence of cargo specificity in the requirement for particular ESCRT (endosomal sorting complex required for transport) proteins to sort cargo into the luminal vesicles of MVBs (multivesicular bodies). We have focussed on studying the ESCRT requirements for delivery of MHC class I to lysosomes following polyubiquitination by the Kaposi's sarcoma-associated herpesvirus protein K3. Down-regulation of polyubiquitinated cell-surface MHC class I in HeLa cells stably expressing K3 is achieved via clathrin-mediated endocytosis, followed by sorting into the luminal vesicles of MVBs and eventual delivery to lysosomes. Depletion of ESCRT-I and some ESCRT-III components interferes with this sorting and allows recycling of MHC class I to the cell surface. Depletion of ESCRT-II components has no effect on K3-mediated down-regulation of MHC class I and no gross morphological effect on endocytic compartments. Thus virally polyubiquitinated MHC class I does not require all of the ESCRT proteins in order to be sorted into the luminal vesicles of MVBs. However, there may be a further requirement for ESCRT-III proteins to ensure the efficient fusion of MVBs with lysosomes.
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Pincetic A, Leis J. The Mechanism of Budding of Retroviruses From Cell Membranes. Adv Virol 2009; 2009:6239691-6239699. [PMID: 19865606 PMCID: PMC2768365 DOI: 10.1155/2009/623969] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2008] [Accepted: 12/18/2008] [Indexed: 11/17/2022] Open
Abstract
Retroviruses have evolved a mechanism for the release of particles from the cell membrane that appropriates cellular protein complexes, referred to as ESCRT-I, -II, -III, normally involved in the biogenesis of multivesicular bodies. Three different classes of late assembly (L) domains encoded in Gag, with core sequences of PPXY, PTAP, and YPXL, recruit different components of the ESCRT machinery to form a budding complex for virus release. Here, we highlight recent progress in identifying the role of different ESCRT complexes in facilitating budding, ubiquitination, and membrane targeting of avian sarcoma and leukosis virus (ASLV) and human immunodeficiency virus, type 1 (HIV-1). These findings show that retroviruses adopt parallel budding pathways by recruiting different host factors from common cellular machinery for particle release.
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Affiliation(s)
- Andrew Pincetic
- Department of Microbiology and Immunology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Jonathan Leis
- Department of Microbiology and Immunology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
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Harty RN. No exit: targeting the budding process to inhibit filovirus replication. Antiviral Res 2008; 81:189-97. [PMID: 19114059 DOI: 10.1016/j.antiviral.2008.12.003] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2008] [Revised: 11/25/2008] [Accepted: 12/01/2008] [Indexed: 01/15/2023]
Abstract
The filoviruses, Ebola and Marburg, cause severe hemorrhagic fever in humans and nonhuman primates, with high mortality rates. Although the filovirus replication pathway is now understood in considerable detail, no antiviral drugs have yet been developed that directly inhibit steps in the replication cycle. One potential target is the filovirus VP40 matrix protein, the key viral protein that drives the budding process, in part by mediating specific virus-host interactions to facilitate the efficient release of virions from the infected cell. This review will summarize current knowledge of key structural and functional domains of VP40 believed to be necessary for efficient budding of virions and virus-like particles. A better understanding of the structure and function of these key regions of VP40 will be crucial, as they may represent novel and rational targets for inhibitors of filovirus egress.
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Affiliation(s)
- Ronald N Harty
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, 3800 Spruce Street, Philadelphia, PA 19104, USA.
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