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Abstract
Most enveloped viruses encode viral fusion proteins to penetrate host cell by membrane fusion. Interestingly, many enveloped viruses can also use viral fusion proteins to induce cell-cell fusion, both in vitro and in vivo, leading to the formation of syncytia or multinucleated giant cells (MGCs). In addition, some non-enveloped viruses encode specialized viral proteins that induce cell-cell fusion to facilitate viral spread. Overall, viruses that can induce cell-cell fusion are nearly ubiquitous in mammals. Virus cell-to-cell spread by inducing cell-cell fusion may overcome entry and post-entry blocks in target cells and allow evasion of neutralizing antibodies. However, molecular mechanisms of virus-induced cell-cell fusion remain largely unknown. Here, I summarize the current understanding of virus-induced cell fusion and syncytia formation.
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Affiliation(s)
- Maorong Xie
- Division of Infection and Immunity, UCL, London, UK.
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2
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Boulton S, Crupi MJF, Singh S, Carter-Timofte ME, Azad T, Organ BC, He X, Gill R, Neault S, Jamieson T, Dave J, Kurmasheva N, Austin B, Petryk J, Singaravelu R, Huang BZ, Franco N, Babu K, Parks RJ, Ilkow CS, Olagnier D, Bell JC. Inhibition of Exchange Proteins Directly Activated by cAMP (EPAC) as a Strategy for Broad-Spectrum Antiviral Development. J Biol Chem 2023; 299:104749. [PMID: 37100284 PMCID: PMC10124099 DOI: 10.1016/j.jbc.2023.104749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 04/17/2023] [Accepted: 04/18/2023] [Indexed: 04/28/2023] Open
Abstract
The recent SARS-CoV-2 and mpox outbreaks have highlighted the need to expand our arsenal of broad-spectrum antiviral agents for future pandemic preparedness. Host-directed antivirals are an important tool to accomplish this as they typically offer protection against a broader range of viruses than direct-acting antivirals and have a lower susceptibility to viral mutations that cause drug resistance. In this study, we investigate the Exchange Protein Activated by cAMP (EPAC) as a target for broad-spectrum antiviral therapy. We find that the EPAC-selective inhibitor, ESI-09 provides robust protection against a variety of viruses, including SARS-CoV-2 and Vaccinia (VACV) - an orthopoxvirus from the same family as mpox. We show, using a series of immunofluorescence experiments, that ESI-09 remodels the actin cytoskeleton through Rac1/Cdc42 GTPases and the Arp2/3 complex, impairing internalization of viruses that use clathrin-mediated endocytosis (e.g. VSV) or micropinocytosis (e.g. VACV). Additionally, we find that ESI-09 disrupts syncytia formation and inhibits cell-to-cell transmission of viruses such as measles and VACV. When administered to immune-deficient mice in an intranasal challenge model, ESI-09 protects mice from lethal doses of VACV and prevents formation of pox lesions. Altogether, our finding show that EPAC antagonists such as ESI-09 are promising candidates for broad-spectrum antiviral therapy that can aid in the fight against ongoing and future viral outbreaks.
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Affiliation(s)
- Stephen Boulton
- Ottawa Hospital Research Institute, Ottawa, ON, K1H 8L6, Canada; Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, K1H 8M5, Canada.
| | - Mathieu J F Crupi
- Ottawa Hospital Research Institute, Ottawa, ON, K1H 8L6, Canada; Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, K1H 8M5, Canada
| | - Siddharth Singh
- Ottawa Hospital Research Institute, Ottawa, ON, K1H 8L6, Canada; Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, K1H 8M5, Canada
| | | | - Taha Azad
- Ottawa Hospital Research Institute, Ottawa, ON, K1H 8L6, Canada; Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, K1H 8M5, Canada; Faculty of Medicine and Health Sciences, Department of microbiology and infectious diseases, Université de Sherbrooke, Sherbrooke, QC J1E 4K8, Canada; Centre de Recherche du CHUS, Sherbrooke, QC J1H 5N4, Canada
| | - Bailey C Organ
- Ottawa Hospital Research Institute, Ottawa, ON, K1H 8L6, Canada; Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, K1H 8M5, Canada
| | - Xiaohong He
- Ottawa Hospital Research Institute, Ottawa, ON, K1H 8L6, Canada; Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, K1H 8M5, Canada
| | - Rida Gill
- Ottawa Hospital Research Institute, Ottawa, ON, K1H 8L6, Canada; Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, K1H 8M5, Canada
| | - Serge Neault
- Ottawa Hospital Research Institute, Ottawa, ON, K1H 8L6, Canada; Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, K1H 8M5, Canada
| | - Taylor Jamieson
- Ottawa Hospital Research Institute, Ottawa, ON, K1H 8L6, Canada; Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, K1H 8M5, Canada
| | - Jaahnavi Dave
- Ottawa Hospital Research Institute, Ottawa, ON, K1H 8L6, Canada; Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, K1H 8M5, Canada
| | - Naziia Kurmasheva
- Aarhus University, Department of Biomedicine, Aarhus C, 8000, Denmark
| | - Bradley Austin
- Ottawa Hospital Research Institute, Ottawa, ON, K1H 8L6, Canada
| | - Julia Petryk
- Ottawa Hospital Research Institute, Ottawa, ON, K1H 8L6, Canada
| | - Ragunath Singaravelu
- Ottawa Hospital Research Institute, Ottawa, ON, K1H 8L6, Canada; Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, K1H 8M5, Canada; Public Health Agency of Canada, Ottawa, Ontario, Canada, K1A 0K9
| | - Ben Zhen Huang
- Ottawa Hospital Research Institute, Ottawa, ON, K1H 8L6, Canada; Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, K1H 8M5, Canada
| | - Noah Franco
- Ottawa Hospital Research Institute, Ottawa, ON, K1H 8L6, Canada; Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, K1H 8M5, Canada
| | - Kaaviya Babu
- Ottawa Hospital Research Institute, Ottawa, ON, K1H 8L6, Canada; Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, K1H 8M5, Canada
| | - Robin J Parks
- Ottawa Hospital Research Institute, Ottawa, ON, K1H 8L6, Canada; Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, K1H 8M5, Canada; Department of Medicine, University of Ottawa, Ottawa, ON, K1H 8M5, Canada
| | - Carolina S Ilkow
- Ottawa Hospital Research Institute, Ottawa, ON, K1H 8L6, Canada; Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, K1H 8M5, Canada
| | - David Olagnier
- Aarhus University, Department of Biomedicine, Aarhus C, 8000, Denmark
| | - John C Bell
- Ottawa Hospital Research Institute, Ottawa, ON, K1H 8L6, Canada; Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, K1H 8M5, Canada; Department of Medicine, University of Ottawa, Ottawa, ON, K1H 8M5, Canada.
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3
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Role of Host Small GTPases in Apicomplexan Parasite Infection. Microorganisms 2022; 10:microorganisms10071370. [PMID: 35889089 PMCID: PMC9319929 DOI: 10.3390/microorganisms10071370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 07/01/2022] [Accepted: 07/04/2022] [Indexed: 12/04/2022] Open
Abstract
The Apicomplexa are obligate intracellular parasites responsible for several important human diseases. These protozoan organisms have evolved several strategies to modify the host cell environment to create a favorable niche for their survival. The host cytoskeleton is widely manipulated during all phases of apicomplexan intracellular infection. Moreover, the localization and organization of host organelles are altered in order to scavenge nutrients from the host. Small GTPases are a class of proteins widely involved in intracellular pathways governing different processes, from cytoskeletal and organelle organization to gene transcription and intracellular trafficking. These proteins are already known to be involved in infection by several intracellular pathogens, including viruses, bacteria and protozoan parasites. In this review, we recapitulate the mechanisms by which apicomplexan parasites manipulate the host cell during infection, focusing on the role of host small GTPases. We also discuss the possibility of considering small GTPases as potential targets for the development of novel host-targeted therapies against apicomplexan infections.
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Nickoloff-Bybel EA, Festa L, Meucci O, Gaskill PJ. Co-receptor signaling in the pathogenesis of neuroHIV. Retrovirology 2021; 18:24. [PMID: 34429135 PMCID: PMC8385912 DOI: 10.1186/s12977-021-00569-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 08/11/2021] [Indexed: 12/13/2022] Open
Abstract
The HIV co-receptors, CCR5 and CXCR4, are necessary for HIV entry into target cells, interacting with the HIV envelope protein, gp120, to initiate several signaling cascades thought to be important to the entry process. Co-receptor signaling may also promote the development of neuroHIV by contributing to both persistent neuroinflammation and indirect neurotoxicity. But despite the critical importance of CXCR4 and CCR5 signaling to HIV pathogenesis, there is only one therapeutic (the CCR5 inhibitor Maraviroc) that targets these receptors. Moreover, our understanding of co-receptor signaling in the specific context of neuroHIV is relatively poor. Research into co-receptor signaling has largely stalled in the past decade, possibly owing to the complexity of the signaling cascades and functions mediated by these receptors. Examining the many signaling pathways triggered by co-receptor activation has been challenging due to the lack of specific molecular tools targeting many of the proteins involved in these pathways and the wide array of model systems used across these experiments. Studies examining the impact of co-receptor signaling on HIV neuropathogenesis often show activation of multiple overlapping pathways by similar stimuli, leading to contradictory data on the effects of co-receptor activation. To address this, we will broadly review HIV infection and neuropathogenesis, examine different co-receptor mediated signaling pathways and functions, then discuss the HIV mediated signaling and the differences between activation induced by HIV and cognate ligands. We will assess the specific effects of co-receptor activation on neuropathogenesis, focusing on neuroinflammation. We will also explore how the use of substances of abuse, which are highly prevalent in people living with HIV, can exacerbate the neuropathogenic effects of co-receptor signaling. Finally, we will discuss the current state of therapeutics targeting co-receptors, highlighting challenges the field has faced and areas in which research into co-receptor signaling would yield the most therapeutic benefit in the context of HIV infection. This discussion will provide a comprehensive overview of what is known and what remains to be explored in regard to co-receptor signaling and HIV infection, and will emphasize the potential value of HIV co-receptors as a target for future therapeutic development. ![]()
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Affiliation(s)
- E A Nickoloff-Bybel
- Department of Pharmacology and Physiology, Drexel University College of Medicine, 245 N. 15th Street, Philadelphia, PA, 19102, USA
| | - L Festa
- Department of Basic and Translational Sciences, School of Dental Medicine, University of Pennsylvania, 240 S. 40th Street, Philadelphia, PA, 19104, USA
| | - O Meucci
- Department of Pharmacology and Physiology, Drexel University College of Medicine, 245 N. 15th Street, Philadelphia, PA, 19102, USA.,Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, PA, 19102, USA
| | - P J Gaskill
- Department of Pharmacology and Physiology, Drexel University College of Medicine, 245 N. 15th Street, Philadelphia, PA, 19102, USA.
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5
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Tavares LA, Januário YC, daSilva LLP. HIV-1 Hijacking of Host ATPases and GTPases That Control Protein Trafficking. Front Cell Dev Biol 2021; 9:622610. [PMID: 34307340 PMCID: PMC8295591 DOI: 10.3389/fcell.2021.622610] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 06/07/2021] [Indexed: 12/22/2022] Open
Abstract
The human immunodeficiency virus (HIV-1) modifies the host cell environment to ensure efficient and sustained viral replication. Key to these processes is the capacity of the virus to hijack ATPases, GTPases and the associated proteins that control intracellular protein trafficking. The functions of these energy-harnessing enzymes can be seized by HIV-1 to allow the intracellular transport of viral components within the host cell or to change the subcellular distribution of antiviral factors, leading to immune evasion. Here, we summarize how energy-related proteins deviate from their normal functions in host protein trafficking to aid the virus in different phases of its replicative cycle. Recent discoveries regarding the interplay among HIV-1 and host ATPases and GTPases may shed light on potential targets for pharmacological intervention.
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Affiliation(s)
- Lucas A Tavares
- Department of Cell and Molecular Biology, Center for Virology Research, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
| | - Yunan C Januário
- Department of Cell and Molecular Biology, Center for Virology Research, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
| | - Luis L P daSilva
- Department of Cell and Molecular Biology, Center for Virology Research, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
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Abstract
A critical step in the life cycle of a virus is spread to a new target cell, which generally involves the release of new viral particles from the infected cell which can then initiate infection in the next target cell. While cell-free viral particles released into the extracellular environment are necessary for long distance spread, there are disadvantages to this mechanism. These include the presence of immune system components, the low success rate of infection by single particles, and the relative fragility of viral particles in the environment. Several mechanisms of direct cell-to-cell spread have been reported for animal viruses which would avoid the issues associated with cell-free particles. A number of viruses can utilize several different mechanisms of direct cell-to-cell spread, but our understanding of the differential usage by these pathogens is modest. Although the mechanisms of cell-to-cell spread differ among viruses, there is a common exploitation of key pathways and components of the cellular cytoskeleton. Remarkably, some of the viral mechanisms of cell-to-cell spread are surprisingly similar to those used by bacteria. Here we summarize the current knowledge of the conventional and non-conventional mechanisms of viral spread, the common methods used to detect viral spread, and the impact that these mechanisms can have on viral pathogenesis.
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Affiliation(s)
- Nicolas Cifuentes-Munoz
- Instituto de Ciencias Biomédicas, Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, San Miguel, Santiago, Chile
| | - Farah El Najjar
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY, United States
| | - Rebecca Ellis Dutch
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY, United States.
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Llorente García I, Marsh M. A biophysical perspective on receptor-mediated virus entry with a focus on HIV. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2020; 1862:183158. [PMID: 31863725 PMCID: PMC7156917 DOI: 10.1016/j.bbamem.2019.183158] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 12/12/2019] [Accepted: 12/13/2019] [Indexed: 12/14/2022]
Abstract
As part of their entry and infection strategy, viruses interact with specific receptor molecules expressed on the surface of target cells. The efficiency and kinetics of the virus-receptor interactions required for a virus to productively infect a cell is determined by the biophysical properties of the receptors, which are in turn influenced by the receptors' plasma membrane (PM) environments. Currently, little is known about the biophysical properties of these receptor molecules or their engagement during virus binding and entry. Here we review virus-receptor interactions focusing on the human immunodeficiency virus type 1 (HIV), the etiological agent of acquired immunodeficiency syndrome (AIDS), as a model system. HIV is one of the best characterised enveloped viruses, with the identity, roles and structure of the key molecules required for infection well established. We review current knowledge of receptor-mediated HIV entry, addressing the properties of the HIV cell-surface receptors, the techniques used to measure these properties, and the macromolecular interactions and events required for virus entry. We discuss some of the key biophysical principles underlying receptor-mediated virus entry and attempt to interpret the available data in the context of biophysical mechanisms. We also highlight crucial outstanding questions and consider how new tools might be applied to advance understanding of the biophysical properties of viral receptors and the dynamic events leading to virus entry.
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Affiliation(s)
| | - Mark Marsh
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, UK
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8
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Das SK, Sarkar D, Emdad L, Fisher PB. MDA-9/Syntenin: An emerging global molecular target regulating cancer invasion and metastasis. Adv Cancer Res 2019; 144:137-191. [PMID: 31349898 DOI: 10.1016/bs.acr.2019.03.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
With few exceptions, metastasis is the terminal stage of cancer with limited therapeutic options. Metastasis consists of numerous phenotypic and genotypic alterations of cells that are directly and indirectly induced by multiple intrinsic (cellular) and extrinsic (micro-environmental) factors. To metastasize, a cancer cell often transitions from an epithelial to mesenchymal morphology (EMT), modifies the extracellular matrix, forms emboli and survives in the circulation, escapes immune surveillance, adheres to sites distant from the initial tumor and finally develops a blood supply (angiogenesis) and colonizes in a secondary niche (a micrometastasis). Scientific advances have greatly enhanced our understanding of the precise molecular and genetic changes, operating independently or collectively, that lead to metastasis. This review focuses on a unique gene, melanoma differentiation associated gene-9 (also known as Syntenin-1; Syndecan Binding Protein (sdcbp); mda-9/syntenin), initially cloned and characterized from metastatic human melanoma and shown to be a pro-metastatic gene. In the last two decades, our comprehension of the diversity of actions of MDA-9/Syntenin on cellular phenotype has emerged. MDA-9/Sytenin plays pivotal regulatory roles in multiple signaling cascades and orchestrates both metastatic and non-metastatic events. Considering the relevance of this gene in controlling cancer invasion and metastasis, approaches have been developed to uniquely and selectively target this gene. We also provide recent updates on strategies that have been successfully employed in targeting MDA-9/Syntenin resulting in profound pre-clinical anti-cancer activity.
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Affiliation(s)
- Swadesh K Das
- Department of Human and Molecular Genetics, Virginia Commonwealth University, School of Medicine, Richmond, VA, United States; VCU Institute of Molecular Medicine, Virginia Commonwealth University, School of Medicine, Richmond, VA, United States; VCU Massey Cancer Center, Virginia Commonwealth University, School of Medicine, Richmond, VA, United States.
| | - Devanand Sarkar
- Department of Human and Molecular Genetics, Virginia Commonwealth University, School of Medicine, Richmond, VA, United States; VCU Institute of Molecular Medicine, Virginia Commonwealth University, School of Medicine, Richmond, VA, United States; VCU Massey Cancer Center, Virginia Commonwealth University, School of Medicine, Richmond, VA, United States
| | - Luni Emdad
- Department of Human and Molecular Genetics, Virginia Commonwealth University, School of Medicine, Richmond, VA, United States; VCU Institute of Molecular Medicine, Virginia Commonwealth University, School of Medicine, Richmond, VA, United States; VCU Massey Cancer Center, Virginia Commonwealth University, School of Medicine, Richmond, VA, United States
| | - Paul B Fisher
- Department of Human and Molecular Genetics, Virginia Commonwealth University, School of Medicine, Richmond, VA, United States; VCU Institute of Molecular Medicine, Virginia Commonwealth University, School of Medicine, Richmond, VA, United States; VCU Massey Cancer Center, Virginia Commonwealth University, School of Medicine, Richmond, VA, United States.
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HIV-1 Envelope Glycoproteins Induce the Production of TNF-α and IL-10 in Human Monocytes by Activating Calcium Pathway. Sci Rep 2018; 8:17215. [PMID: 30464243 PMCID: PMC6249280 DOI: 10.1038/s41598-018-35478-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 10/30/2018] [Indexed: 12/19/2022] Open
Abstract
Human HIV-1 infection leads inevitably to a chronic hyper-immune-activation. However, the nature of the targeted receptors and the pathways involved remain to be fully elucidated. We demonstrate that X4-tropic gp120 induced the production of TNF-α and IL-10 by monocytes through activation of a cell membrane receptor, distinct from the CD4, CXCR4, and MR receptors. Gp120 failed to stimulate IL-10 and TNF-α production by monocytes in Ca2+ free medium. This failure was total for IL-10 and partial for TNF-α. However, IL-10 and TNF-α production was fully restored following the addition of exogenous calcium. Accordingly, addition of BAPTA-AM and cyclosporine-A, fully and partially inhibited IL-10 and TNF-α respectively. The PKA pathway was crucial for IL-10 production but only partially involved in gp120-induced TNF-α. The PLC pathway was partially and equivalently involved in gp120-induced TNF-α and IL-10. Moreover, the inhibition of PI3K, ERK1/2, p38 MAP-kinases and NF-κB pathways totally abolished the production of both cytokines. In conclusion, this study revealed the crucial calcium signaling pathway triggered by HIV-1 gp120 to control the production of these two cytokines: TNF-α and IL-10. The finding could help in the development of a new therapeutic strategy to alleviate the chronic hyper-immune-activation observed in HIV-1 infected patients.
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Abstract
Human immunodeficiency virus (HIV)-associated neurocognitive disorders (HAND) remain a common end-organ manifestation of viral infection. Subclinical and mild symptoms lead to neurocognitive and behavioral abnormalities. These are associated, in part, with viral penetrance and persistence in the central nervous system. Infections of peripheral blood monocytes, macrophages, and microglia are the primary drivers of neuroinflammation and neuronal impairments. While current antiretroviral therapy (ART) has reduced the incidence of HIV-associated dementia, milder forms of HAND continue. Depression, comorbid conditions such as infectious liver disease, drugs of abuse, antiretroviral drugs themselves, age-related neurodegenerative diseases, gastrointestinal maladies, and concurrent social and economic issues can make accurate diagnosis of HAND challenging. Increased life expectancy as a result of ART clearly creates this variety of comorbid conditions that often blur the link between the virus and disease. With the discovery of novel biomarkers, neuropsychologic testing, and imaging techniques to better diagnose HAND, the emergence of brain-penetrant ART, adjunctive therapies, longer life expectancy, and better understanding of disease pathogenesis, disease elimination is perhaps a realistic possibility. This review focuses on HIV-associated disease pathobiology with an eye towards changing trends in the face of widespread availability of ART.
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Cuartas-López AM, Hernández-Cuellar CE, Gallego-Gómez JC. Disentangling the role of PI3K/Akt, Rho GTPase and the actin cytoskeleton on dengue virus infection. Virus Res 2018; 256:153-165. [DOI: 10.1016/j.virusres.2018.08.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 07/30/2018] [Accepted: 08/14/2018] [Indexed: 12/22/2022]
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Azab W, Osterrieder K. Initial Contact: The First Steps in Herpesvirus Entry. ADVANCES IN ANATOMY EMBRYOLOGY AND CELL BIOLOGY 2018; 223:1-27. [PMID: 28528437 DOI: 10.1007/978-3-319-53168-7_1] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The entry process of herpesviruses into host cells is complex and highly variable. It involves a sequence of well-orchestrated events that begin with virus attachment to glycan-containing proteinaceous structures on the cell surface. This initial contact tethers virus particles to the cell surface and results in a cascade of molecular interactions, including the tight interaction of viral envelope glycoproteins to specific cell receptors. These interactions trigger intracellular signaling and finally virus penetration after fusion of the viral envelope with cellular membranes. Based on the engaged cellular receptors and co-receptors, and the subsequent signaling cascades, the entry pathway will be decided on the spot. A number of viral glycoproteins and many cellular receptors and molecules have been identified as players in one or several of these events during virus entry. This chapter will review viral glycoproteins, cellular receptors and signaling cascades associated with the very first interactions of herpesviruses with their target cells.
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Affiliation(s)
- Walid Azab
- Institut für Virologie, Robert von Ostertag-Haus, Zentrum für Infektionsmedizin, Freie Universität Berlin, Robert-von-Ostertag-Str. 7-13, 14163, Berlin, Germany.
| | - Klaus Osterrieder
- Institut für Virologie, Robert von Ostertag-Haus, Zentrum für Infektionsmedizin, Freie Universität Berlin, Robert-von-Ostertag-Str. 7-13, 14163, Berlin, Germany
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13
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Ospina Stella A, Turville S. All-Round Manipulation of the Actin Cytoskeleton by HIV. Viruses 2018; 10:v10020063. [PMID: 29401736 PMCID: PMC5850370 DOI: 10.3390/v10020063] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Revised: 01/24/2018] [Accepted: 01/29/2018] [Indexed: 12/21/2022] Open
Abstract
While significant progress has been made in terms of human immunodeficiency virus (HIV) therapy, treatment does not represent a cure and remains inaccessible to many people living with HIV. Continued mechanistic research into the viral life cycle and its intersection with many aspects of cellular biology are not only fundamental in the continued fight against HIV, but also provide many key observations of the workings of our immune system. Decades of HIV research have testified to the integral role of the actin cytoskeleton in both establishing and spreading the infection. Here, we review how the virus uses different strategies to manipulate cellular actin networks and increase the efficiency of various stages of its life cycle. While some HIV proteins seem able to bind to actin filaments directly, subversion of the cytoskeleton occurs indirectly by exploiting the power of actin regulatory proteins, which are corrupted at multiple levels. Furthermore, this manipulation is not restricted to a discrete class of proteins, but rather extends throughout all layers of the cytoskeleton. We discuss prominent examples of actin regulators that are exploited, neutralized or hijacked by the virus, and address how their coordinated deregulation can lead to changes in cellular behavior that promote viral spreading.
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Affiliation(s)
- Alberto Ospina Stella
- The Kirby Institute, University of New South Wales (UNSW), Sydney NSW 2052, Australia.
| | - Stuart Turville
- The Kirby Institute, University of New South Wales (UNSW), Sydney NSW 2052, Australia.
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14
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Aggarwal A, Hitchen TL, Ootes L, McAllery S, Wong A, Nguyen K, McCluskey A, Robinson PJ, Turville SG. HIV infection is influenced by dynamin at 3 independent points in the viral life cycle. Traffic 2017; 18:392-410. [PMID: 28321960 DOI: 10.1111/tra.12481] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 03/16/2017] [Accepted: 03/16/2017] [Indexed: 12/19/2022]
Abstract
CD4 T cells are important cellular targets for HIV-1, yet the primary site of HIV fusion remains unresolved. Candidate fusion sites are either the plasma membrane or from within endosomes. One area of investigation compounding the controversy of this field, is the role of the protein dynamin in the HIV life cycle. To understand the role of dynamin in primary CD4 T cells we combined dynamin inhibition with a series of complementary assays based on single particle tracking, HIV fusion, detection of HIV DNA products and active viral transcription. We identify 3 levels of dynamin influence on the HIV life cycle. Firstly, dynamin influences productive infection by preventing cell cycle progression. Secondly, dynamin influences endocytosis rates and increases the probability of endosomal fusion. Finally, we provide evidence in resting CD4 T cells that dynamin directly regulates the HIV fusion reaction at the plasma membrane. We confirm this latter observation using 2 divergent dynamin modulating compounds, one that enhances dynamin conformations associated with dynamin ring formation (ryngo-1-23) and the other that preferentially targets dynamin conformations that appear in helices (dyngo-4a). This in-depth understanding of dynamin's roles in HIV infection clarifies recent controversies and furthermore provides evidence for dynamin regulation specifically in the HIV fusion reaction.
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Affiliation(s)
- Anupriya Aggarwal
- The Kirby Institute, University of New South Wales, New South Wales, Australia
| | - Tina L Hitchen
- The Kirby Institute, University of New South Wales, New South Wales, Australia
| | - Lars Ootes
- The Kirby Institute, University of New South Wales, New South Wales, Australia
| | - Samantha McAllery
- The Kirby Institute, University of New South Wales, New South Wales, Australia
| | - Andrew Wong
- The Kirby Institute, University of New South Wales, New South Wales, Australia
| | - Khanh Nguyen
- The Kirby Institute, University of New South Wales, New South Wales, Australia
| | - Adam McCluskey
- Centre for Chemical Biology, Chemistry, School of Environmental and Life Sciences, The University of Newcastle, Callaghan, Australia
| | - Phillip J Robinson
- Children's Medical Research Institute, The University of Sydney, New South Wales, Australia
| | - Stuart G Turville
- The Kirby Institute, University of New South Wales, New South Wales, Australia
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Morillon YM, Lessey-Morillon EC, Clark M, Zhang R, Wang B, Burridge K, Tisch R. Antibody Binding to CD4 Induces Rac GTPase Activation and Alters T Cell Migration. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2016; 197:3504-3511. [PMID: 27694496 PMCID: PMC5101163 DOI: 10.4049/jimmunol.1501600] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Accepted: 09/02/2016] [Indexed: 12/18/2022]
Abstract
The use of nondepleting Abs specific for CD4 and CD8 is an effective strategy to tolerize CD4+ and CD8+ T cells in a tissue-specific manner. We reported that coreceptor therapy reverses diabetes in new onset NOD mice. A striking feature of coreceptor-induced remission is the purging of T cells from the pancreatic lymph nodes (PLN) and islets of NOD mice. Evidence indicates that Abs binding to the coreceptors promotes T cell egress from these tissues. The present study examined how coreceptor therapy affects the migration of CD4+ T cells residing in the PLN of NOD mice. Anti-CD4 Ab treatment resulted in an increased frequency of PLN but not splenic CD4+ T cells that exhibited a polarized morphology consistent with a migratory phenotype. Furthermore, PLN CD4+ T cells isolated from anti-CD4 versus control Ab-treated animals displayed increased in vitro chemotaxis to chemoattractants such as sphingosine-1-phosphate and CXCL12. Notably, the latter was dependent on activation of the small Rho GTPases Rac1 and Rac2. Rac1 and Rac2 activation was increased in Ab-bound CD4+ T cells from the PLN but not the spleen, and knockdown of Rac expression blocked the heightened reactivity of Ab-bound PLN CD4+ T cells to CXCL12. Interestingly, Rac1 and Rac2 activation was independent of Rac guanine nucleotide exchange factors known to regulate T cell activity. Therefore, Ab binding to CD4 initiates a novel pathway that involves inflammation-dependent activation of Rac and establishment of altered T cell migratory properties.
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Affiliation(s)
- Y. Maurice Morillon
- Department of Microbiology & Immunology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599 USA
| | - Elizabeth Chase Lessey-Morillon
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599 USA
| | - Matthew Clark
- Department of Microbiology & Immunology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599 USA
| | - Rui Zhang
- Department of Microbiology & Immunology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599 USA
| | - Bo Wang
- Department of Microbiology & Immunology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599 USA
| | - Keith Burridge
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599 USA
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599 USA
- McAllister Heart Institute, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599 USA
| | - Roland Tisch
- Department of Microbiology & Immunology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599 USA
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599 USA
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Binding of alphaherpesvirus glycoprotein H to surface α4β1-integrins activates calcium-signaling pathways and induces phosphatidylserine exposure on the plasma membrane. mBio 2015; 6:e01552-15. [PMID: 26489864 PMCID: PMC4620472 DOI: 10.1128/mbio.01552-15] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Intracellular signaling connected to integrin activation is known to induce cytoplasmic Ca2+ release, which in turn mediates a number of downstream signals. The cellular entry pathways of two closely related alphaherpesviruses, equine herpesviruses 1 and 4 (EHV-1 and EHV-4), are differentially regulated with respect to the requirement of interaction of glycoprotein H (gH) with α4β1-integrins. We show here that binding of EHV-1, but not EHV-4, to target cells resulted in a rapid and significant increase in cytosolic Ca2+ levels. EHV-1 expressing EHV-4 gH (gH4) in lieu of authentic gH1 failed to induce Ca2+ release, while EHV-4 with gH1 triggered significant Ca2+ release. Blocking the interaction between gH1 and α4β1-integrins, inhibiting phospholipase C (PLC) activation, or blocking binding of inositol 1,4,5-triphosphate (IP3) to its receptor on the endoplasmic reticulum (ER) abrogated Ca2+ release. Interestingly, phosphatidylserine (PS) was exposed on the plasma membrane in response to cytosolic calcium increase after EHV-1 binding through a scramblase-dependent mechanism. Inhibition of both Ca2+ release from the ER and scramblase activation blocked PS scrambling and redirected virus entry to the endocytic pathway, indicating that PS may play a role in facilitating virus entry directly at the plasma membrane. Herpesviruses are a large family of enveloped viruses that infect a wide range of hosts, causing a variety of diseases. These viruses have developed a number of strategies for successful entry into different cell types. We and others have shown that alphaherpesviruses, including EHV-1 and herpes simplex virus 1 (HSV-1), can route their entry pathway and do so by manipulation of cell signaling cascades to ensure viral genome delivery to nuclei. We show here that the interaction between EHV-1 gH and cellular α4β1-integrins is necessary to induce emptying of ER calcium stores, which induces phosphatidylserine exposure on the plasma membrane through a scramblase-dependent mechanism. This change in lipid asymmetry facilitates virus entry and might help fusion of the viral envelope at the plasma membrane. These findings will help to advance our understanding of herpesvirus entry mechanism and may facilitate the development of novel drugs that can be implemented for prevention of infection and disease.
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Involvement of the Rac1-IRSp53-Wave2-Arp2/3 Signaling Pathway in HIV-1 Gag Particle Release in CD4 T Cells. J Virol 2015; 89:8162-81. [PMID: 26018170 DOI: 10.1128/jvi.00469-15] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2015] [Accepted: 05/14/2015] [Indexed: 12/18/2022] Open
Abstract
UNLABELLED During HIV-1 assembly, the Gag viral proteins are targeted and assemble at the inner leaflet of the cell plasma membrane. This process could modulate the cortical actin cytoskeleton, located underneath the plasma membrane, since actin dynamics are able to promote localized membrane reorganization. In addition, activated small Rho GTPases are known for regulating actin dynamics and membrane remodeling. Therefore, the modulation of such Rho GTPase activity and of F-actin by the Gag protein during virus particle formation was considered. Here, we studied the implication of the main Rac1, Cdc42, and RhoA small GTPases, and some of their effectors, in this process. The effect of small interfering RNA (siRNA)-mediated Rho GTPases and silencing of their effectors on Gag localization, Gag membrane attachment, and virus-like particle production was analyzed by immunofluorescence coupled to confocal microscopy, membrane flotation assays, and immunoblot assays, respectively. In parallel, the effect of Gag expression on the Rac1 activation level was monitored by G-LISA, and the intracellular F-actin content in T cells was monitored by flow cytometry and fluorescence microscopy. Our results revealed the involvement of activated Rac1 and of the IRSp53-Wave2-Arp2/3 signaling pathway in HIV-1 Gag membrane localization and particle release in T cells as well as a role for actin branching and polymerization, and this was solely dependent on the Gag viral protein. In conclusion, our results highlight a new role for the Rac1-IRSp53-Wave2-Arp2/3 signaling pathway in the late steps of HIV-1 replication in CD4 T lymphocytes. IMPORTANCE During HIV-1 assembly, the Gag proteins are targeted and assembled at the inner leaflet of the host cell plasma membrane. Gag interacts with specific membrane phospholipids that can also modulate the regulation of cortical actin cytoskeleton dynamics. Actin dynamics can promote localized membrane reorganization and thus can be involved in facilitating Gag assembly and particle formation. Activated small Rho GTPases and effectors are regulators of actin dynamics and membrane remodeling. We thus studied the effects of the Rac1, Cdc42, and RhoA GTPases and their specific effectors on HIV-1 Gag membrane localization and viral particle release in T cells. Our results show that activated Rac1 and the IRSp53-Wave2-Arp2/3 signaling pathway are involved in Gag plasma membrane localization and viral particle production. This work uncovers a role for cortical actin through the activation of Rac1 and the IRSp53/Wave2 signaling pathway in HIV-1 particle formation in CD4 T lymphocytes.
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18
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Kondo N, Marin M, Kim JH, Desai TM, Melikyan GB. Distinct requirements for HIV-cell fusion and HIV-mediated cell-cell fusion. J Biol Chem 2015; 290:6558-73. [PMID: 25589785 DOI: 10.1074/jbc.m114.623181] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Whether HIV-1 enters cells by fusing with the plasma membrane or with endosomes is a subject of active debate. The ability of HIV-1 to mediate fusion between adjacent cells, a process referred to as "fusion-from-without" (FFWO), shows that this virus can fuse with the plasma membrane. To compare FFWO occurring at the cell surface with HIV-cell fusion through a conventional entry route, we designed an experimental approach that enabled the measurements of both processes in the same sample. The following key differences were observed. First, a very small fraction of viruses fusing with target cells participated in FFWO. Second, whereas HIV-1 fusion with adherent cells was insensitive to actin inhibitors, post-CD4/coreceptor binding steps during FFWO were abrogated. A partial dependence of HIV-cell fusion on actin remodeling was observed in CD4(+) T cells, but this effect appeared to be due to the actin dependence of virus uptake. Third, deletion of the cytoplasmic tail of HIV-1 gp41 dramatically enhanced the ability of the virus to promote FFWO, while having a modest effect on virus-cell fusion. Distinct efficiencies and actin dependences of FFWO versus HIV-cell fusion are consistent with the notion that, except for a minor fraction of particles that mediate fusion between the plasma membranes of adjacent cells, HIV-1 enters through an endocytic pathway. We surmise, however, that cell-cell contacts enabling HIV-1 fusion with the plasma membrane could be favored at the sites of high density of target cells, such as lymph nodes.
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Affiliation(s)
- Naoyuki Kondo
- From the Division of Pediatric Infectious Diseases, Emory University Children's Center, Atlanta and
| | - Mariana Marin
- From the Division of Pediatric Infectious Diseases, Emory University Children's Center, Atlanta and
| | - Jeong Hwa Kim
- From the Division of Pediatric Infectious Diseases, Emory University Children's Center, Atlanta and
| | - Tanay M Desai
- From the Division of Pediatric Infectious Diseases, Emory University Children's Center, Atlanta and
| | - Gregory B Melikyan
- From the Division of Pediatric Infectious Diseases, Emory University Children's Center, Atlanta and Children's Healthcare of Atlanta, Atlanta, Georgia 30322
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Santos G, Valenzuela-Fernández A, Torres NV. Quantitative analysis of the processes and signaling events involved in early HIV-1 infection of T cells. PLoS One 2014; 9:e103845. [PMID: 25105875 PMCID: PMC4126662 DOI: 10.1371/journal.pone.0103845] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2014] [Accepted: 07/02/2014] [Indexed: 11/24/2022] Open
Abstract
Lymphocyte invasion by HIV-1 is a complex, highly regulated process involving many different types of molecules that is prompted by the virus's association with viral receptors located at the cell-surface membrane that culminates in the formation of a fusion pore through which the virus enters the cell. A great deal of work has been done to identify the key actors in the process and determine the regulatory interactions; however, there have been no reports to date of attempts being made to fully understand the system dynamics through a systemic, quantitative modeling approach. In this paper, we introduce a dynamic mathematical model that integrates the available information on the molecular events involved in lymphocyte invasion. Our model shows that moesin activation is induced by virus signaling, while filamin-A is mobilized by the receptor capping. Actin disaggregation from the cap is facilitated by cofilin. Cofilin is inactivated by HIV-1 signaling in activated lymphocytes, while in resting lymphocytes another signal is required to activate cofilin in the later stages in order to accelerate the decay of the aggregated actin as a restriction factor for the viral entry. Furthermore, stopping the activation signaling of moesin is sufficient to liberate the actin filaments from the cap. The model also shows the positive effect of gelsolin on actin capping by means of the nucleation effect. These findings allow us to propose novel approaches in the search for new therapeutic strategies. In particular, gelsolin inhibition is seen as a promising target for preventing HIV-1 entry into lymphocytes, due to its role in facilitating the capping needed for the invasion. Also it is shown that HIV-1 should overcome the cortical actin barrier during early infection and predicts the different susceptibility of CD4+ T cells to be infected in terms of actin cytoskeleton dynamics driven by associated cellular factors.
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Affiliation(s)
- Guido Santos
- Grupo de Biología de Sistemas y Modelización Matemática, Departamento de Bioquímica, Microbiología, Biología Celular y Genética, Facultad de Biología, Universidad de La Laguna, San Cristóbal de La Laguna, Tenerife, España
- Instituto de Tecnología Biomédica, Universidad de La Laguna, San Cristóbal de La Laguna, Tenerife, Spain
| | - Agustín Valenzuela-Fernández
- Laboratorio de Inmunología Celular y Viral, Departamento de Medicina Física y Farmacología, Facultad de Medicina, Universidad de La Laguna, San Cristóbal de La Laguna, Tenerife, España
- * E-mail: (AV-F); (NVT)
| | - Néstor V. Torres
- Grupo de Biología de Sistemas y Modelización Matemática, Departamento de Bioquímica, Microbiología, Biología Celular y Genética, Facultad de Biología, Universidad de La Laguna, San Cristóbal de La Laguna, Tenerife, España
- Instituto de Tecnología Biomédica, Universidad de La Laguna, San Cristóbal de La Laguna, Tenerife, Spain
- * E-mail: (AV-F); (NVT)
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20
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Zhong Y, Johnson AJ, Byrd JC, Dubovsky JA. Targeting Interleukin-2-Inducible T-cell Kinase (ITK) in T-Cell Related Diseases. ACTA ACUST UNITED AC 2014; 2:1-11. [PMID: 27917390 DOI: 10.14304/surya.jpr.v2n6.1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
IL2-inducible T-cell kinase (ITK), a member of the Tec family tyrosine kinases, is the predominant Tec kinase in T cells and natural killer (NK) cells mediating T cell receptor (TCR) and Fc receptor (Fc R) initiated signal transduction. ITK deficiency results in impaired T and NK cell functions, leading to various disorders including malignancies, inflammation, and autoimmune diseases. In this mini-review, the role of ITK in T cell signaling and the development of small molecule inhibitors of ITK for the treatment of T-cell related disorders is examined.
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Affiliation(s)
- Yiming Zhong
- Division of Hematology, Department of Internal Medicine, The Ohio State University, 320 W. 10th Avenue, Columbus, OH 43210, USA
| | - Amy J Johnson
- Division of Hematology, Department of Internal Medicine, The Ohio State University, 320 W. 10th Avenue, Columbus, OH 43210, USA
| | - John C Byrd
- Division of Hematology, Department of Internal Medicine, The Ohio State University, 320 W. 10th Avenue, Columbus, OH 43210, USA
| | - Jason A Dubovsky
- Division of Hematology, Department of Internal Medicine, The Ohio State University, 320 W. 10th Avenue, Columbus, OH 43210, USA
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Ezrin is a component of the HIV-1 virological presynapse and contributes to the inhibition of cell-cell fusion. J Virol 2014; 88:7645-58. [PMID: 24760896 DOI: 10.1128/jvi.00550-14] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED During cell-to-cell transmission of HIV-1, viral and cellular proteins transiently accumulate at the contact zone between infected (producer) and uninfected (target) cells, forming the virological synapse. Rearrangements of the cytoskeleton in producer and target cells are required for proper targeting of viral and cellular components during synapse formation, yet little is known about how these processes are regulated, particularly within the producer cell. Since ezrin-radixin-moesin (ERM) proteins connect F-actin with integral and peripheral membrane proteins, are incorporated into virions, and interact with cellular components of the virological presynapse, we hypothesized that they play roles during the late stage of HIV-1 replication. Here we document that phosphorylated (i.e., active) ezrin specifically accumulates at the HIV-1 presynapse in T cell lines and primary CD4(+) lymphocytes. To investigate whether ezrin supports virus transmission, we sought to ablate ezrin expression in producer cells. While cells did not tolerate a complete knockdown of ezrin, even a modest reduction of ezrin expression (~50%) in HIV-1-producing cells led to the release of particles with impaired infectivity. Further, when cocultured with uninfected target cells, ezrin-knockdown producer cells displayed reduced accumulation of the tetraspanin CD81 at the synapse and fused more readily with target cells, thus forming syncytia. Such an outcome likely is not optimal for virus dissemination, as evidenced by the fact that, in vivo, only relatively few infected cells form syncytia. Thus, ezrin likely helps secure efficient virus spread not only by enhancing virion infectivity but also by preventing excessive membrane fusion at the virological synapse. IMPORTANCE While viruses, in principal, can propagate through successions of syncytia, HIV-1-infected cells in the majority of cases do not fuse with potential target cells during viral transmission. This mode of spread is coresponsible for key features of HIV-1 pathogenesis, including killing of bystander cells and establishment of latently infected T lymphocytes. Here we identify the ERM protein family member ezrin as a cellular factor that contributes to the inhibition of cell-cell fusion and thus to suppressing excessive syncytium formation. Our analyses further suggest that ezrin, which connects integral membrane proteins with actin, functions in concert with CD81, a member of the tetraspanin family of proteins. Additional evidence, documented here and elsewhere, suggests that ezrin and CD81 cooperate to prevent cytoskeleton rearrangements that need to take place during the fusion of cellular membranes.
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HIV-1 induces cytoskeletal alterations and Rac1 activation during monocyte-blood-brain barrier interactions: modulatory role of CCR5. Retrovirology 2014; 11:20. [PMID: 24571616 PMCID: PMC4015682 DOI: 10.1186/1742-4690-11-20] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Accepted: 01/07/2014] [Indexed: 01/06/2023] Open
Abstract
Background Most HIV strains that enter the brain are macrophage-tropic and use the CCR5 receptor to bind and infect target cells. Because the cytoskeleton is a network of protein filaments involved in cellular movement and migration, we investigated whether CCR5 and the cytoskeleton are involved in endothelial-mononuclear phagocytes interactions, adhesion, and HIV-1 infection. Results Using a cytoskeleton phospho-antibody microarray, we showed that after co-culture with human brain microvascular endothelial cells (HBMEC), HIV-1 infected monocytes increased expression and activation of cytoskeleton-associated proteins, including Rac1/cdc42 and cortactin, compared to non-infected monocytes co-cultured with HBMEC. Analysis of brain tissues from HIV-1-infected patients validated these findings, and showed transcriptional upregulation of Rac1 and cortactin, as well as increased activation of Rac1 in brain tissues of HIV-1-infected humans, compared to seronegative individuals and subjects with HIV-1-encephalitis. Confocal imaging showed that brain cells expressing phosphorylated Rac1 were mostly macrophages and blood vessels. CCR5 antagonists TAK-799 and maraviroc prevented HIV-induced upregulation and phosphorylation of cytoskeleton-associated proteins, prevented HIV-1 infection of macrophages, and diminished viral-induced adhesion of monocytes to HBMEC. Ingenuity pathway analysis suggests that during monocyte-endothelial interactions, HIV-1 alters protein expression and phosphorylation associated with integrin signaling, cellular morphology and cell movement, cellular assembly and organization, and post-translational modifications in monocytes. CCR5 antagonists prevented these HIV-1-induced alterations. Conclusions HIV-1 activates cytoskeletal proteins during monocyte-endothelial interactions and increase transcription and activation of Rac1 in brain tissues. In addition to preventing macrophage infection, CCR5 antagonists could diminish viral-induced alteration and phosphorylation of cytoskeletal proteins, monocyte adhesion to the brain endothelium and viral entry into the central nervous system.
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23
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Flanagan CA. Receptor Conformation and Constitutive Activity in CCR5 Chemokine Receptor Function and HIV Infection. ADVANCES IN PHARMACOLOGY 2014; 70:215-63. [DOI: 10.1016/b978-0-12-417197-8.00008-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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24
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Dürr R, Keppler O, Christ F, Crespan E, Garbelli A, Maga G, Dietrich U. Targeting Cellular Cofactors in HIV Therapy. TOPICS IN MEDICINAL CHEMISTRY 2014. [DOI: 10.1007/7355_2014_45] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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25
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Melikyan GB. HIV entry: a game of hide-and-fuse? Curr Opin Virol 2013; 4:1-7. [PMID: 24525288 DOI: 10.1016/j.coviro.2013.09.004] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 09/19/2013] [Accepted: 09/25/2013] [Indexed: 11/24/2022]
Abstract
Human Immunodeficiency Virus (HIV) initiates infection by fusing its envelope membrane with the cell membrane through a process which is triggered through interactions with the cellular receptor and coreceptor. Although the mechanism of HIV fusion has been extensively studied, the point of its entry into cells remains controversial. HIV has long been thought to fuse directly with the cell plasma membrane. However, several lines of evidence suggest that endocytic entry of HIV can lead to infection and, moreover, that endocytosis could be the predominant HIV entry pathway into different cell types. This review discusses recent findings pertinent to HIV entry routes and novel approaches to pinpoint the sites of virus entry.
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Affiliation(s)
- Gregory B Melikyan
- Division of Pediatric Infectious Diseases, Emory University Children's Center, 2015 Uppergate Drive, Atlanta, GA 30322, USA.
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26
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Gordón-Alonso M, Rocha-Perugini V, Álvarez S, Ursa Á, Izquierdo-Useros N, Martinez-Picado J, Muñoz-Fernández MA, Sánchez-Madrid F. Actin-binding protein drebrin regulates HIV-1-triggered actin polymerization and viral infection. J Biol Chem 2013; 288:28382-97. [PMID: 23926103 DOI: 10.1074/jbc.m113.494906] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
HIV-1 contact with target cells triggers F-actin rearrangements that are essential for several steps of the viral cycle. Successful HIV entry into CD4(+) T cells requires actin reorganization induced by the interaction of the cellular receptor/co-receptor complex CD4/CXCR4 with the viral envelope complex gp120/gp41 (Env). In this report, we analyze the role of the actin modulator drebrin in HIV-1 viral infection and cell to cell fusion. We show that drebrin associates with CXCR4 before and during HIV infection. Drebrin is actively recruited toward cell-virus and Env-driven cell to cell contacts. After viral internalization, drebrin clustering is retained in a fraction of the internalized particles. Through a combination of RNAi-based inhibition of endogenous drebrin and GFP-tagged expression of wild-type and mutant forms, we establish drebrin as a negative regulator of HIV entry and HIV-mediated cell fusion. Down-regulation of drebrin expression promotes HIV-1 entry, decreases F-actin polymerization, and enhances profilin local accumulation in response to HIV-1. These data underscore the negative role of drebrin in HIV infection by modulating viral entry, mainly through the control of actin cytoskeleton polymerization in response to HIV-1.
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Affiliation(s)
- Mónica Gordón-Alonso
- From the Servicio de Inmunología, Instituto de Investigación Sanitaria de la Princesa, Hospital Universitario de la Princesa, 28006 Madrid, Spain
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Salgado APC, Soares-Martins JAP, Andrade LG, Albarnaz JD, Ferreira PCP, Kroon EG, Bonjardim CA. Study of vaccinia and cowpox viruses' replication in Rac1-N17 dominant-negative cells. Mem Inst Oswaldo Cruz 2013; 108:554-62. [PMID: 23903969 DOI: 10.1590/s0074-02762013000500004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Accepted: 05/13/2013] [Indexed: 11/22/2022] Open
Abstract
Interfering with cellular signal transduction pathways is a common strategy used by many viruses to create a propitious intracellular environment for an efficient replication. Our group has been studying cellular signalling pathways activated by the orthopoxviruses Vaccinia (VACV) and Cowpox (CPXV) and their significance to viral replication. In the present study our aim was to investigate whether the GTPase Rac1 was an upstream signal that led to the activation of MEK/ERK1/2, JNK1/2 or Akt pathways upon VACV or CPXV' infections. Therefore, we generated stable murine fibroblasts exhibiting negative dominance to Rac1-N17 to evaluate viral growth and the phosphorylation status of ERK1/2, JNK1/2 and Akt. Our results demonstrated that VACV replication, but not CPXV, was affected in dominant-negative (DN) Rac1-N17 cell lines in which viral yield was reduced in about 10-fold. Viral late gene expression, but not early, was also reduced. Furthermore, our data showed that Akt phosphorylation was diminished upon VACV infection in DN Rac1-N17 cells, suggesting that Rac1 participates in the phosphoinositide-3 kinase pathway leading to the activation of Akt. In conclusion, our results indicate that while Rac1 indeed plays a role in VACV biology, perhaps another GTPase may be involved in CPXV replication.
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Affiliation(s)
- Ana Paula Carneiro Salgado
- Grupo de Transdução de Sinal/Orthopoxvirus e Flavivírus - LABVÍRUS, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brasil
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28
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Salgado APC, Soares-Martins JAP, Andrade LG, Albarnaz JD, Ferreira PCP, Kroon EG, Bonjardim CA. Study of vaccinia and cowpox viruses' replication in Rac1-N17 dominant-negative cells. Mem Inst Oswaldo Cruz 2013; 108. [PMID: 23903969 PMCID: PMC3970603 DOI: 10.1590/0074-0276108052013004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Interfering with cellular signal transduction pathways is a common strategy used by many viruses to create a propitious intracellular environment for an efficient replication. Our group has been studying cellular signalling pathways activated by the orthopoxviruses Vaccinia (VACV) and Cowpox (CPXV) and their significance to viral replication. In the present study our aim was to investigate whether the GTPase Rac1 was an upstream signal that led to the activation of MEK/ERK1/2, JNK1/2 or Akt pathways upon VACV or CPXV' infections. Therefore, we generated stable murine fibroblasts exhibiting negative dominance to Rac1-N17 to evaluate viral growth and the phosphorylation status of ERK1/2, JNK1/2 and Akt. Our results demonstrated that VACV replication, but not CPXV, was affected in dominant-negative (DN) Rac1-N17 cell lines in which viral yield was reduced in about 10-fold. Viral late gene expression, but not early, was also reduced. Furthermore, our data showed that Akt phosphorylation was diminished upon VACV infection in DN Rac1-N17 cells, suggesting that Rac1 participates in the phosphoinositide-3 kinase pathway leading to the activation of Akt. In conclusion, our results indicate that while Rac1 indeed plays a role in VACV biology, perhaps another GTPase may be involved in CPXV replication.
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Affiliation(s)
- Ana Paula Carneiro Salgado
- Grupo de Transdução de Sinal/Orthopoxvirus e Flavivírus - LABVÍRUS , Laboratório de Vírus, Departamento de Microbiologia, Instituto de
Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG,
Brasil
| | - Jamária Adriana Pinheiro Soares-Martins
- Grupo de Transdução de Sinal/Orthopoxvirus e Flavivírus - LABVÍRUS , Laboratório de Vírus, Departamento de Microbiologia, Instituto de
Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG,
Brasil , Department of Microbiology and Molecular Genetics, Medical College
of Wisconsin, Milwaukee, WI, USA
| | - Luciana Garcia Andrade
- Grupo de Transdução de Sinal/Orthopoxvirus e Flavivírus - LABVÍRUS , Laboratório de Vírus, Departamento de Microbiologia, Instituto de
Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG,
Brasil
| | - Jonas Dutra Albarnaz
- Grupo de Transdução de Sinal/Orthopoxvirus e Flavivírus - LABVÍRUS , Laboratório de Vírus, Departamento de Microbiologia, Instituto de
Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG,
Brasil
| | - Paulo César Peregrino Ferreira
- Laboratório de Vírus, Departamento de Microbiologia, Instituto de
Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG,
Brasil
| | - Erna Geessien Kroon
- Laboratório de Vírus, Departamento de Microbiologia, Instituto de
Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG,
Brasil
| | - Cláudio Antônio Bonjardim
- Grupo de Transdução de Sinal/Orthopoxvirus e Flavivírus - LABVÍRUS , Laboratório de Vírus, Departamento de Microbiologia, Instituto de
Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG,
Brasil , Corresponding author:
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Nogalski MT, Chan GCT, Stevenson EV, Collins-McMillen DK, Yurochko AD. The HCMV gH/gL/UL128-131 complex triggers the specific cellular activation required for efficient viral internalization into target monocytes. PLoS Pathog 2013; 9:e1003463. [PMID: 23853586 PMCID: PMC3708883 DOI: 10.1371/journal.ppat.1003463] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Accepted: 05/13/2013] [Indexed: 12/18/2022] Open
Abstract
We have established that HCMV acts as a specific ligand engaging and activating cellular integrins on monocytes. As a result, integrin signaling via Src activation leads to the functional activation of paxillin required for efficient viral entry and for the biological changes in monocytes needed for viral dissemination. These biological/molecular changes allow HCMV to use monocytes as "vehicles" for systemic spread and the establishment of lifelong persistence. However, it remains unresolved how HCMV specifically induces this observed monocyte activation. It was previously demonstrated that the HCMV gH/gL/UL128-131 glycoprotein complex facilitates viral entry into biologically relevant cell types. Nevertheless, the mechanism by which the gH/gL/UL128-131 complex promotes this process is unknown. We now show that only HCMV virions possessing the gH/gL/UL128-131 complex are capable of activating integrin/Src/paxillin-signaling in monocytes. In fibroblasts, this signaling is reversed, such that virus lacking the gH/gL/UL128-131 complex is the only virus able to induce the paxillin activation cascade. The presence of the gH/gL/UL128-131 complex also may have an inhibitory effect on integrin-mediated signaling pathway in fibroblasts. Furthermore, we demonstrate that the presence of the gH/gL/UL128-131 complex on the viral envelope, through its activation of the integrin/Src/paxillin pathway, is necessary for efficient HCMV internalization into monocytes and that appropriate actin and dynamin regulation is critical for this entry process. Importantly, productive infection in monocyte-derived macrophages was seen only in cells exposed to HCMV expressing the gH/gL/UL128-131 complex. From our data, the HCMV gH/gL/U128-131 complex emerges as the specific ligand driving the activation of the receptor-mediated signaling required for the regulation of the actin cytoskeleton and, consequently, for efficient and productive internalization of HCMV into monocytes. To our knowledge, our studies demonstrate a possible molecular mechanism for why the gH/gL/UL128-131 complex dictates HCMV tropism and why the complex is lost as clinical isolates are passaged in the laboratory.
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Affiliation(s)
- Maciej T. Nogalski
- Department of Microbiology and Immunology, Center for Molecular and Tumor Virology, Louisiana State University Health Sciences Center, Shreveport, Louisiana, United States of America
| | - Gary C. T. Chan
- Department of Microbiology and Immunology, Center for Molecular and Tumor Virology, Louisiana State University Health Sciences Center, Shreveport, Louisiana, United States of America
| | - Emily V. Stevenson
- Department of Microbiology and Immunology, Center for Molecular and Tumor Virology, Louisiana State University Health Sciences Center, Shreveport, Louisiana, United States of America
| | - Donna K. Collins-McMillen
- Department of Microbiology and Immunology, Center for Molecular and Tumor Virology, Louisiana State University Health Sciences Center, Shreveport, Louisiana, United States of America
| | - Andrew D. Yurochko
- Department of Microbiology and Immunology, Center for Molecular and Tumor Virology, Louisiana State University Health Sciences Center, Shreveport, Louisiana, United States of America
- Feist-Weiller Cancer Center, Louisiana State University Health Sciences Center, Shreveport, Louisiana, United States of America
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Guo J, Xu X, Rasheed TK, Yoder A, Yu D, Liang H, Yi F, Hawley T, Jin T, Ling B, Wu Y. Genistein interferes with SDF-1- and HIV-mediated actin dynamics and inhibits HIV infection of resting CD4 T cells. Retrovirology 2013; 10:62. [PMID: 23782904 PMCID: PMC3693989 DOI: 10.1186/1742-4690-10-62] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Accepted: 06/10/2013] [Indexed: 11/23/2022] Open
Abstract
Background Binding of HIV to the chemokine coreceptor CXCR4 mediates viral fusion and signal transduction that promotes actin dynamics critical for HIV infection of blood resting CD4 T cells. It has been suggested that this gp120-mediated actin activity resembles the chemotactic actin dynamics mediated by chemokines such as SDF-1. To determine whether inhibiting SDF-1-mediated chemotactic activity can also inhibit HIV infection, we screened several inhibitors known to reduce SDF-1-mediated chemotaxis of T cells. Results We found that a tyrosine kinase inhibitor, genistein, inhibited both SDF-1-mediated chemotaxis and HIV infection of resting CD4 T cells. Genistein was also found to interfere with SDF-1- and HIV-mediated actin dynamics in CD4 T cells. This reduction in actin activity correlates with genistein-mediated inhibition of viral DNA accumulation in resting CD4 T cells. In addition, we also tested two other tyrosine kinase inhibitors, sunitinib and AG1478. Sunitinib, but not AG1478, inhibited HIV infection of resting CD4 T cells. We further tested the safety of genistein in 3 Chinese rhesus macaques (Macaca mulatta), and each animal was given a monotherapy of genistein at 10 mg/kg orally for 12 weeks. No adverse drug effects were observed in these animals. Conclusions Our results suggest that novel therapeutic strategies can be developed based on targeting cellular proteins involved in HIV-dependent signaling. This approach can interfere with HIV-mediated actin dynamics and inhibit HIV infection.
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Affiliation(s)
- Jia Guo
- National Center for Biodefense and Infectious Diseases, Department of Molecular and Microbiology, George Mason University, Manassas VA 20110, USA.
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García-Expósito L, Ziglio S, Barroso-González J, de Armas-Rillo L, Valera MS, Zipeto D, Machado JD, Valenzuela-Fernández A. Gelsolin activity controls efficient early HIV-1 infection. Retrovirology 2013; 10:39. [PMID: 23575248 PMCID: PMC3626799 DOI: 10.1186/1742-4690-10-39] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2012] [Accepted: 03/27/2013] [Indexed: 01/06/2023] Open
Abstract
Background HIV-1 entry into target lymphocytes requires the activity of actin adaptors that stabilize and reorganize cortical F-actin, like moesin and filamin-A. These alterations are necessary for the redistribution of CD4-CXCR4/CCR5 to one pole of the cell, a process that increases the probability of HIV-1 Envelope (Env)-CD4/co-receptor interactions and that generates the tension at the plasma membrane necessary to potentiate fusion pore formation, thereby favouring early HIV-1 infection. However, it remains unclear whether the dynamic processing of F-actin and the amount of cortical actin available during the initial virus-cell contact are required to such events. Results Here we show that gelsolin restructures cortical F-actin during HIV-1 Env-gp120-mediated signalling, without affecting cell-surface expression of receptors or viral co-receptor signalling. Remarkably, efficient HIV-1 Env-mediated membrane fusion and infection of permissive lymphocytes were impaired when gelsolin was either overexpressed or silenced, which led to a loss or gain of cortical actin, respectively. Indeed, HIV-1 Env-gp120-induced F-actin reorganization and viral receptor capping were impaired under these experimental conditions. Moreover, gelsolin knockdown promoted HIV-1 Env-gp120-mediated aberrant pseudopodia formation. These perturbed-actin events are responsible for the inhibition of early HIV-1 infection. Conclusions For the first time we provide evidence that through its severing of cortical actin, and by controlling the amount of actin available for reorganization during HIV-1 Env-mediated viral fusion, entry and infection, gelsolin can constitute a barrier that restricts HIV-1 infection of CD4+ lymphocytes in a pre-fusion step. These findings provide important insights into the complex molecular and actin-associated dynamics events that underlie early viral infection. Thus, we propose that gelsolin is a new factor that can limit HIV-1 infection acting at a pre-fusion step, and accordingly, cell-signals that regulate gelsolin expression and/or its actin-severing activity may be crucial to combat HIV-1 infection.
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Affiliation(s)
- Laura García-Expósito
- Cellular and Viral Immunology Lab, Department of Physical Medicine and Pharmacology, School of Medicine, University of La Laguna, Campus de Ofra s/n, Tenerife 38071, Spain
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Anand AR, Zhao H, Nagaraja T, Robinson LA, Ganju RK. N-terminal Slit2 inhibits HIV-1 replication by regulating the actin cytoskeleton. Retrovirology 2013; 10:2. [PMID: 23294842 PMCID: PMC3562244 DOI: 10.1186/1742-4690-10-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Accepted: 12/17/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Slit2 is a ~ 200 kDa secreted glycoprotein that has been recently shown to regulate immune functions. However, not much is known about its role in HIV (human immunodeficiency virus)-1 pathogenesis. RESULTS In the present study, we have shown that the N-terminal fragment of Slit2 (Slit2N) (~120 kDa) inhibits replication of both CXCR4 and CCR5-tropic HIV-1 viruses in T-cell lines and peripheral blood T-cells. Furthermore, we demonstrated inhibition of HIV-1 infection in resting CD4+ T-cells. In addition, we showed that Slit2N blocks cell-to-cell transmission of HIV-1. We have shown that Slit2N inhibits HIV-1 infection by blocking viral entry into T-cells. We also ruled out Slit2N-mediated inhibition of various other steps in the life cycle including binding, integration and viral transcription. Elucidation of the molecular mechanism revealed that Slit2N mediates its functional effects by binding to Robo1 receptor. Furthermore, we found that Slit2N inhibited Gp120-induced Robo1-actin association suggesting that Slit2N may inhibit cytoskeletal rearrangements facilitating HIV-1 entry. Studies into the mechanism of inhibition of HIV-1 revealed that Slit2N abrogated HIV-1 envelope-induced actin cytoskeletal dynamics in both T-cell lines and primary T-cells. We further showed that Slit2N specifically attenuated the HIV-1 envelope-induced signaling pathway consisting of Rac1, LIMK and cofilin that regulates actin polymerization. CONCLUSIONS Taken together, our results show that Slit2N inhibits HIV-1 replication through novel mechanisms involving modulation of cytoskeletal dynamics. Our study, thus, provides insights into the role of Slit2N in HIV-1 infection and underscores its potential in limiting viral replication in T-cells.
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Affiliation(s)
- Appakkudal R Anand
- Department of Pathology, Ohio State University Wexner Medical Center, 460 W 12th Avenue, 810 Biological Research Tower, Columbus, OH 43210, USA
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Watanabe T, Urano E, Miyauchi K, Ichikawa R, Hamatake M, Misawa N, Sato K, Ebina H, Koyanagi Y, Komano J. The hematopoietic cell-specific Rho GTPase inhibitor ARHGDIB/D4GDI limits HIV type 1 replication. AIDS Res Hum Retroviruses 2012; 28:913-22. [PMID: 21936715 DOI: 10.1089/aid.2011.0180] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Rho GTPases are able to influence the replication of human immunodeficiency virus type 1 (HIV-1). However, little is known about the regulation of HIV-1 replication by guanine nucleotide dissociation inhibitors (GDIs), one of the three major regulators of the Rho GTPase activation cycle. From a T cell-based cDNA library screening, ARHGDIB/RhoGDIβ, a hematopoietic lineage-specific GDI family protein, was identified as a negative regulator of HIV-1 replication. Up-regulation of ARHGDIB attenuated the replication of HIV-1 in multiple T cell lines. The results showed that (1) a significant portion of RhoA and Rac1, but not Cdc42, exists in the GTP-bound active form under steady-state conditions, (2) ectopic ARHGDIB expression reduced the F-actin content and the active forms of both RhoA and Rac1, and (3) HIV-1 infection was attenuated by either ectopic expression of ARHGDIB or inhibition of the RhoA signal cascade at the HIV-1 Env-dependent early phase of the viral life cycle. This is in good agreement with the previous finding that RhoA and Rac1 promote HIV-1 entry by increasing the efficiency of receptor clustering and virus-cell membrane fusion. In conclusion, the ARHGDIB is a lymphoid-specific intrinsic negative regulator of HIV-1 replication that acts by simultaneously inhibiting RhoA and Rac1 functions.
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Affiliation(s)
- Tadashi Watanabe
- Laboratory of Viral Pathogenesis, Institute for Virus Research, Kyoto University, Kyoto, Japan
| | - Emiko Urano
- AIDS Research Center, National Institute of Infectious Diseases, Tokyo, Japan
| | - Kosuke Miyauchi
- AIDS Research Center, National Institute of Infectious Diseases, Tokyo, Japan
| | - Reiko Ichikawa
- AIDS Research Center, National Institute of Infectious Diseases, Tokyo, Japan
| | - Makiko Hamatake
- AIDS Research Center, National Institute of Infectious Diseases, Tokyo, Japan
| | - Naoko Misawa
- Laboratory of Viral Pathogenesis, Institute for Virus Research, Kyoto University, Kyoto, Japan
| | - Kei Sato
- Laboratory of Viral Pathogenesis, Institute for Virus Research, Kyoto University, Kyoto, Japan
| | - Hirotaka Ebina
- Laboratory of Viral Pathogenesis, Institute for Virus Research, Kyoto University, Kyoto, Japan
| | - Yoshio Koyanagi
- Laboratory of Viral Pathogenesis, Institute for Virus Research, Kyoto University, Kyoto, Japan
| | - Jun Komano
- AIDS Research Center, National Institute of Infectious Diseases, Tokyo, Japan
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Spear M, Guo J, Wu Y. The trinity of the cortical actin in the initiation of HIV-1 infection. Retrovirology 2012; 9:45. [PMID: 22640593 PMCID: PMC3416652 DOI: 10.1186/1742-4690-9-45] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Accepted: 05/03/2012] [Indexed: 12/16/2022] Open
Abstract
For an infecting viral pathogen, the actin cortex inside the host cell is the first line of intracellular components that it encounters. Viruses devise various strategies to actively engage or circumvent the actin structure. In this regard, the human immunodeficiency virus-1 (HIV-1) exemplifies command of cellular processes to take control of actin dynamics for the initiation of infection. It has becomes increasingly evident that cortical actin presents itself both as a barrier to viral intracellular migration and as a necessary cofactor that the virus must actively engage, particularly, in the infection of resting CD4 blood T cells, the primary targets of HIV-1. The coercion of this most fundamental cellular component permits infection by facilitating entry, reverse transcription, and nuclear migration, three essential processes for the establishment of viral infection and latency in blood T cells. It is the purpose of this review to examine, in detail, the manifestation of viral dependence on the actin cytoskeleton, and present a model of how HIV utilizes actin dynamics to initiate infection.
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Affiliation(s)
- Mark Spear
- National Center for Biodefense and Infectious Diseases, Department of Molecular and Microbiology, George Mason University, Manassas, VA 20110, USA
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35
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Poxvirus cell entry: how many proteins does it take? Viruses 2012; 4:688-707. [PMID: 22754644 PMCID: PMC3386626 DOI: 10.3390/v4050688] [Citation(s) in RCA: 147] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Revised: 04/21/2012] [Accepted: 04/23/2012] [Indexed: 11/30/2022] Open
Abstract
For many viruses, one or two proteins enable cell binding, membrane fusion and entry. The large number of proteins employed by poxviruses is unprecedented and may be related to their ability to infect a wide range of cells. There are two main infectious forms of vaccinia virus, the prototype poxvirus: the mature virion (MV), which has a single membrane, and the extracellular enveloped virion (EV), which has an additional outer membrane that is disrupted prior to fusion. Four viral proteins associated with the MV membrane facilitate attachment by binding to glycosaminoglycans or laminin on the cell surface, whereas EV attachment proteins have not yet been identified. Entry can occur at the plasma membrane or in acidified endosomes following macropinocytosis and involves actin dynamics and cell signaling. Regardless of the pathway or whether the MV or EV mediates infection, fusion is dependent on 11 to 12 non-glycosylated, transmembrane proteins ranging in size from 4- to 43-kDa that are associated in a complex. These proteins are conserved in poxviruses making it likely that a common entry mechanism exists. Biochemical studies support a two-step process in which lipid mixing of viral and cellular membranes is followed by pore expansion and core penetration.
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36
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Gordón-Alonso M, Rocha-Perugini V, Álvarez S, Moreno-Gonzalo O, Ursa A, López-Martín S, Izquierdo-Useros N, Martínez-Picado J, Muñoz-Fernández MÁ, Yáñez-Mó M, Sánchez-Madrid F. The PDZ-adaptor protein syntenin-1 regulates HIV-1 entry. Mol Biol Cell 2012; 23:2253-63. [PMID: 22535526 PMCID: PMC3374745 DOI: 10.1091/mbc.e11-12-1003] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Syntenin-1 is recruited to the human immunodeficiency virus (HIV)-induced capping area but vanishes once the viral particles have entered the cell. Syntenin-1 limits HIV-1 infection. Moreover, syntenin-1 depletion specifically increases the HIV-1 entry step without affecting viral attachment to the cell surface. Silencing of syntenin-1 expression blocks actin polymerization triggered by HIV-1 contact and enhances phosphatidylinositol 4,5-bisphosphate production. Syntenin-1 is a cytosolic adaptor protein involved in several cellular processes requiring polarization. Human immunodeficiency virus type 1 (HIV-1) attachment to target CD4+ T-cells induces polarization of the viral receptor and coreceptor, CD4/CXCR4, and cellular structures toward the virus contact area, and triggers local actin polymerization and phosphatidylinositol 4,5-bisphosphate (PIP2) production, which are needed for successful HIV infection. We show that syntenin-1 is recruited to the plasma membrane during HIV-1 attachment and associates with CD4, the main HIV-1 receptor. Syntenin-1 overexpression inhibits HIV-1 production and HIV-mediated cell fusion, while syntenin depletion specifically increases HIV-1 entry. Down-regulation of syntenin-1 expression reduces F-actin polymerization in response to HIV-1. Moreover, HIV-induced PIP2 accumulation is increased in syntenin-1–depleted cells. Once the virus has entered the target cell, syntenin-1 polarization toward the viral nucleocapsid is lost, suggesting a spatiotemporal regulatory role of syntenin-1 in actin remodeling, PIP2 production, and the dynamics of HIV-1 entry.
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Affiliation(s)
- Mónica Gordón-Alonso
- Servicio de Inmunología, Instituto de Investigación Sanitaria de la Princesa, Hospital Universitario de la Princesa, 28006 Madrid, Spain
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Jun S, Ke D, Debiec K, Zhao G, Meng X, Ambrose Z, Gibson GA, Watkins SC, Zhang P. Direct visualization of HIV-1 with correlative live-cell microscopy and cryo-electron tomography. Structure 2012; 19:1573-81. [PMID: 22078557 DOI: 10.1016/j.str.2011.09.006] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Revised: 09/13/2011] [Accepted: 09/17/2011] [Indexed: 11/27/2022]
Abstract
Cryo-electron tomography (cryoET) allows 3D visualization of cellular structures at molecular resolution in a close-to-native state and therefore has the potential to help elucidate early events of HIV-1 infection in host cells. However, structural details of infecting HIV-1 have not been observed, due to technological challenges in working with rare and dynamic HIV-1 particles in human cells. Here, we report structural analysis of HIV-1 and host-cell interactions by means of a correlative high-speed 3D live-cell-imaging and cryoET method. Using this method, we showed under near-native conditions that intact hyperstable mutant HIV-1 cores are released into the cytoplasm of host cells. We further obtained direct evidence to suggest that a hyperstable mutant capsid, E45A, showed delayed capsid disassembly compared to the wild-type capsid. Together, these results demonstrate the advantages of our correlative live-cell and cryoET approach for imaging dynamic processes, such as viral infection.
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Affiliation(s)
- Sangmi Jun
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA
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38
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Kuang YQ, Pang W, Zheng YT, Dupré DJ. NHERF1 regulates gp120-induced internalization and signaling by CCR5, and HIV-1 production. Eur J Immunol 2011; 42:299-310. [PMID: 22028271 DOI: 10.1002/eji.201141801] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2011] [Revised: 09/15/2011] [Accepted: 10/21/2011] [Indexed: 11/10/2022]
Abstract
The scaffolding protein Na(+) /H(+) exchanger regulator factor 1 (NHERF1) plays an important role in the trafficking of G protein-coupled receptors. We previously demonstrated that NHERF1 is involved in chemokine receptor CCR5 homodimer internalization and signal transduction. Given the importance of CCR5 internalization during HIV-1 infection, we evaluated NHERF1's contribution in HIV-1 infection. We challenged human osteosarcoma cells coexpressing CD4 and CCR5 cells expressing either NHERF1 fragment domains or WT NHERF1 with an HIV-1 strain to examine the effects of NHERF1 on HIV-1 entry and replication. WT NHERF1 potentiates HIV-1 envelope gp120-induced CCR5 internalization, and promotes the replication of HIV-1. In order to better understand how NHERF1 affects signal transduction, different domains of NHERF1 were overexpressed in cells to analyze their effect on the different signaling pathways. Here, we show that NHERF1 can associate with CCR5, and promote activation of the gp120-induced MAPK/ERK, focal adhesion kinase and RhoA (Ras homolog gene family member A) signaling pathways. NHERF1 overexpression also increases HIV-1 host cell migration triggered by gp120 via focal adhesion kinase (FAK) signaling. Finally, NHERF1 enhanced actin filament rearrangement in host cells, an important step in post-entry HIV-1 replication events. While postsynaptic density 95/disk-large/zonula occludens 2 (PDZ2) appears to be the major contributor in those events, other domains also participate in the regulation of gp120-induced signaling pathways. Altogether, our results suggest a very important role of the scaffold NHERF1 in the regulation of HIV-1 entry and replication.
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Affiliation(s)
- Yi-Qun Kuang
- Department of Pharmacology, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
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Laliberte JP, Weisberg AS, Moss B. The membrane fusion step of vaccinia virus entry is cooperatively mediated by multiple viral proteins and host cell components. PLoS Pathog 2011; 7:e1002446. [PMID: 22194690 PMCID: PMC3240603 DOI: 10.1371/journal.ppat.1002446] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Accepted: 11/03/2011] [Indexed: 01/05/2023] Open
Abstract
For many viruses, one or two proteins allow cell attachment and entry, which occurs through the plasma membrane or following endocytosis at low pH. In contrast, vaccinia virus (VACV) enters cells by both neutral and low pH routes; four proteins mediate cell attachment and twelve that are associated in a membrane complex and conserved in all poxviruses are dedicated to entry. The aim of the present study was to determine the roles of cellular and viral proteins in initial stages of entry, specifically fusion of the membranes of the mature virion and cell. For analysis of the role of cellular components, we used well characterized inhibitors and measured binding of a recombinant VACV virion containing Gaussia luciferase fused to a core protein; viral and cellular membrane lipid mixing with a self-quenching fluorescent probe in the virion membrane; and core entry with a recombinant VACV expressing firefly luciferase and electron microscopy. We determined that inhibitors of tyrosine protein kinases, dynamin GTPase and actin dynamics had little effect on binding of virions to cells but impaired membrane fusion, whereas partial cholesterol depletion and inhibitors of endosomal acidification and membrane blebbing had a severe effect at the later stage of core entry. To determine the role of viral proteins, virions lacking individual membrane components were purified from cells infected with members of a panel of ten conditional-lethal inducible mutants. Each of the entry protein-deficient virions had severely reduced infectivity and except for A28, L1 and L5 greatly impaired membrane fusion. In addition, a potent neutralizing L1 monoclonal antibody blocked entry at a post-membrane lipid-mixing step. Taken together, these results suggested a 2-step entry model and implicated an unprecedented number of viral proteins and cellular components involved in signaling and actin rearrangement for initiation of virus-cell membrane fusion during poxvirus entry. Poxviruses are large DNA viruses that cause diseases in humans and other animals. To initiate infection, the core of the large, membrane-enveloped particle must penetrate into the cytoplasm where replication occurs. For most enveloped viruses only one or two proteins are needed for attachment and penetration. However, at least sixteen poxvirus proteins are dedicated to entry: four for attachment and twelve for penetration. The latter proteins form the entry fusion complex (EFC) and are conserved in all poxviruses indicating that the entry mechanism has been retained since the origin of the family. The purpose of the present study was to determine the cellular processes and poxviral proteins needed for fusion of the viral and cellular membranes. We found that a variety of inhibitors that interfered with cell signaling and reorganization of the actin cytoskeleton prevented membrane fusion as determined by lipid mixing, whereas others targeted the subsequent stage in entry. In addition, seven viral protein components of the EFC were required for the initial membrane fusion step, whereas three were not. A neutralizing monoclonal antibody to one of the latter also did not interfere with membrane lipid mixing but still prevented core entry supporting a 2-step poxvirus entry model.
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Affiliation(s)
- Jason P. Laliberte
- Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Andrea S. Weisberg
- Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Bernard Moss
- Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail:
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Knockdown of MAP4 and DNAL1 produces a post-fusion and pre-nuclear translocation impairment in HIV-1 replication. Virology 2011; 422:13-21. [PMID: 22018492 DOI: 10.1016/j.virol.2011.09.015] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2011] [Revised: 09/02/2011] [Accepted: 09/13/2011] [Indexed: 02/03/2023]
Abstract
DNAL1 and MAP4 are both microtubule-associated proteins. These proteins were identified as HIV-1 dependency factors in a screen with wild-type HIV-1. In this study we demonstrate that knockdown using DNAL1 and MAP4 siRNAs and shRNAs inhibits HIV-1 infection regardless of envelope. Using a fusion assay, we show that DNAL1 and MAP4 do not impact fusion. By assaying for late reverse transcripts and 2-LTR circles, we show that DNAL1 and MAP4 inhibit both by approximately 50%. These results demonstrate that DNAL1 and MAP4 impact reverse transcription but not nuclear translocation. DNAL1 and MAP4 knockdown cells do not display cytoskeletal defects. Together these experiments indicate that DNAL1 and MAP4 may exert their functions in the HIV life cycle at reverse transcription, prior to nuclear translocation.
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Lehmann M, Nikolic DS, Piguet V. How HIV-1 takes advantage of the cytoskeleton during replication and cell-to-cell transmission. Viruses 2011; 3:1757-76. [PMID: 21994805 PMCID: PMC3187690 DOI: 10.3390/v3091757] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Revised: 08/26/2011] [Accepted: 08/30/2011] [Indexed: 12/29/2022] Open
Abstract
Human immunodeficiency virus 1 (HIV-1) infects T cells, macrophages and dendritic cells and can manipulate their cytoskeleton structures at multiple steps during its replication cycle. Based on pharmacological and genetic targeting of cytoskeleton modulators, new imaging approaches and primary cell culture models, important roles for actin and microtubules during entry and cell-to-cell transfer have been established. Virological synapses and actin-containing membrane extensions can mediate HIV-1 transfer from dendritic cells or macrophage cells to T cells and between T cells. We will review the role of the cytoskeleton in HIV-1 entry, cellular trafficking and cell-to-cell transfer between primary cells.
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Affiliation(s)
- Martin Lehmann
- Department of Microbiology and Molecular Medicine, University Hospital and Medical School of Geneva, Geneva 1211, Switzerland; E-Mails: (M.L.); (D.S.N)
- Department of Dermatology and Venereology, University Hospital and Medical School of Geneva, Geneva 1211, Switzerland
| | - Damjan S. Nikolic
- Department of Microbiology and Molecular Medicine, University Hospital and Medical School of Geneva, Geneva 1211, Switzerland; E-Mails: (M.L.); (D.S.N)
- Department of Dermatology and Venereology, University Hospital and Medical School of Geneva, Geneva 1211, Switzerland
| | - Vincent Piguet
- Department of Microbiology and Molecular Medicine, University Hospital and Medical School of Geneva, Geneva 1211, Switzerland; E-Mails: (M.L.); (D.S.N)
- Department of Dermatology and Venereology, University Hospital and Medical School of Geneva, Geneva 1211, Switzerland
- Department of Dermatology and Wound Healing, Cardiff University School of Medicine and University Hospital of Wales, Cardiff, Wales, CF144XN, UK
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +44-(0)-29-20-744721; Fax: +44-(0)-29-20-744312
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Molecular and cellular mechanisms of mammalian cell fusion. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011; 713:33-64. [PMID: 21432013 DOI: 10.1007/978-94-007-0763-4_4] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The fusion of one cell with another occurs in development, injury and disease. Despite the diversity of fusion events, five steps in sequence appear common. These steps include programming fusion-competent status, chemotaxis, membrane adhesion, membrane fusion, and post-fusion resetting. Recent advances in the field start to reveal the molecules involved in each step. This review focuses on some key molecules and cellular events of cell fusion in mammals. Increasing evidence demonstrates that membrane lipid rafts, adhesion proteins and actin rearrangement are critical in the final step of membrane fusion. Here we propose a new model for the formation and expansion of membrane fusion pores based on recent observations on myotube formation. In this model, membrane lipid rafts first recruit adhesion molecules and align with opposing membranes, with the help of a cortical actin "wall" as a rigid supportive platform. Second, the membrane adhesion proteins interact with each other and trigger actin rearrangement, which leads to rapid dispersion of lipid rafts and flow of a highly fluidic phospholipid bilayer into the site. Finally, the opposing phospholipid bilayers are then pushed into direct contact leading to the formation of fusion pores by the force generated through actin polymerization. The actin polymerization generated force also drives the expansion of the fusion pores. However, several key questions about the process of cell fusion still remain to be explored. The understanding of the mechanisms of cell fusion may provide new opportunities in correcting development disorders or regenerating damaged tissues by inhibiting or promoting molecular events associated with fusion.
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Stolp B, Fackler OT. How HIV takes advantage of the cytoskeleton in entry and replication. Viruses 2011; 3:293-311. [PMID: 21994733 PMCID: PMC3185699 DOI: 10.3390/v3040293] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2011] [Revised: 03/11/2011] [Accepted: 03/19/2011] [Indexed: 01/08/2023] Open
Abstract
The host cell cytoskeleton plays a key role in the life cycle of viral pathogens whose propagation depends on mandatory intracellular steps. Accordingly, also the human immunodeficiency virus type 1 (HIV-1) has evolved strategies to exploit and modulate in particular the actin cytoskeleton for its purposes. This review will recapitulate recent findings on how HIV-1 hijacks the cytoskeleton to facilitate entry into, transport within and egress from host cells as well as to commandeer communication of infected with uninfected bystander cells.
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Affiliation(s)
- Bettina Stolp
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany.
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Vorster PJ, Guo J, Yoder A, Wang W, Zheng Y, Xu X, Yu D, Spear M, Wu Y. LIM kinase 1 modulates cortical actin and CXCR4 cycling and is activated by HIV-1 to initiate viral infection. J Biol Chem 2011; 286:12554-64. [PMID: 21321123 DOI: 10.1074/jbc.m110.182238] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Almost all viral pathogens utilize a cytoskeleton for their entry and intracellular transport. In HIV-1 infection, binding of the virus to blood resting CD4 T cells initiates a temporal course of cortical actin polymerization and depolymerization, a process mimicking the chemotactic response initiated from chemokine receptors. The actin depolymerization has been suggested to promote viral intracellular migration through cofilin-mediated actin treadmilling. However, the role of the virus-mediated actin polymerization in HIV infection is unknown, and the signaling molecules involved remain unidentified. Here we describe a pathogenic mechanism for triggering early actin polymerization through HIV-1 envelope-mediated transient activation of the LIM domain kinase (LIMK), a protein that phosphorylates cofilin. We demonstrate that HIV-mediated LIMK activation is through gp120-triggered transient activation of the Rack-PAK-LIMK pathway, and that knockdown of LIMK through siRNA decreases filamentous actin, increases CXCR4 trafficking, and diminishes viral DNA synthesis. These results suggest that HIV-mediated early actin polymerization may directly regulate the CXCR4 receptor during viral entry and is involved in viral DNA synthesis. Furthermore, we also demonstrate that in resting CD4 T cells, actin polymerization can be triggered through transient treatment with a pharmacological agent, okadaic acid, that activates LIMK and promotes HIV latent infection of resting CD4 T cells. Taken together, our results suggest that HIV hijacks LIMK to control the cortical actin dynamics for the initiation of viral infection of CD4 T cells.
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Affiliation(s)
- Paul J Vorster
- Department of Molecular and Microbiology, George Mason University, Manassas, Virginia 20110, USA
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Effects of microtubule modulators on HIV-1 infection of transformed and resting CD4 T cells. J Virol 2011; 85:3020-4. [PMID: 21209111 DOI: 10.1128/jvi.02462-10] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Previous studies have observed fluorescently labeled HIV particles tracking along microtubule networks for nuclear localization. To provide direct evidence for the involvement of microtubules in early steps of HIV infection of human CD4 T cells, we used multiple microtubule modulators such as paclitaxel (originally called taxol; 1 μM), vinblastine (1 and 10 μM), colchicine (10 and 100 μM), and nocodazole (10 and 100 μM) to disturb microtubule networks in transformed and resting CD4 T cells. Although these drugs disrupted microtubule integrity, almost no inhibition of HIV-1 infection was observed. Our results do not appear to support an essential role for microtubules in the initiation of HIV infection of CD4 T cells.
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Carter GC, Bernstone L, Baskaran D, James W. HIV-1 infects macrophages by exploiting an endocytic route dependent on dynamin, Rac1 and Pak1. Virology 2011; 409:234-50. [DOI: 10.1016/j.virol.2010.10.018] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2010] [Revised: 10/04/2010] [Accepted: 10/13/2010] [Indexed: 01/12/2023]
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Melikyan GB. Membrane fusion mediated by human immunodeficiency virus envelope glycoprotein. CURRENT TOPICS IN MEMBRANES 2011; 68:81-106. [PMID: 21771496 DOI: 10.1016/b978-0-12-385891-7.00004-0] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Gregory B Melikyan
- Department of Pediatrics, Infectious Diseases, Emory University, Atlanta, GA, USA
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Roles of small GTPase Rac1 in the regulation of actin cytoskeleton during dengue virus infection. PLoS Negl Trop Dis 2010; 4. [PMID: 20824170 PMCID: PMC2930870 DOI: 10.1371/journal.pntd.0000809] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2010] [Accepted: 08/03/2010] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Increased vascular permeability is a hallmark feature in severe dengue virus (DV) infection, and dysfunction of endothelial cells has been speculated to contribute in the pathogenesis of dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS). Rho-family GTPase Rac1 is a significant element of endothelial barrier function regulation and has been implicated in the regulation of actin remodeling and intercellular junction formation. Yet there is little evidence linking Rac1 GTPase to alteration in endothelial cell function induced by DV infection. METHODS AND FINDINGS Here, we showed that actin is essential for DV serotype 2 (DV2) entry into and release from ECV304 cells, and Rac1 signaling is involved these processes. At early infection, actin cytoskeleton rearranged significantly during 1 hour post infection, and disrupting actin filament dynamics with jasplakinolide or cytochalasin D reduced DV2 entry. DV2 entry induced reduction of Rac1 activity within 1 hour post infection. The expression of dominant-negative forms of Rac1 established that DV2 entry is negatively regulated by Rac1. At late infection, actin drugs also inhibited the DV2 release and induced accumulation of viral proteins in the cytoplasm. Meanwhile, the activity of Rac1 increased significantly with the progression of DV2 infection and was up-regulated in transfected cells expressing E protein. Confocal microscopy showed that DV2 E protein was closely associated with either actin or Rac1 in DV2-infected cells. The interaction between E protein and actin was further confirmed by co-immunoprecipitation assay. CONCLUSIONS These results defined roles for actin integrity in DV2 entry and release, and indicated evidence for the participation of Rac1 signaling pathways in DV2-induced actin reorganizations and E-actin interaction. Our results may provide further insight into the pathogenesis of DHF/DSS.
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Wurth MA, Schowalter RM, Smith EC, Moncman CL, Dutch RE, McCann RO. The actin cytoskeleton inhibits pore expansion during PIV5 fusion protein-promoted cell-cell fusion. Virology 2010; 404:117-26. [PMID: 20537366 PMCID: PMC2885465 DOI: 10.1016/j.virol.2010.04.024] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2010] [Accepted: 04/22/2010] [Indexed: 11/27/2022]
Abstract
Paramyxovirus fusion (F) proteins promote both virus-cell fusion, required for viral entry, and cell-cell fusion, resulting in syncytia formation. We used the F-actin stabilizing drug, jasplakinolide, and the G-actin sequestrant, latrunculin A, to examine the role of actin dynamics in cell-cell fusion mediated by the parainfluenza virus 5 (PIV5) F protein. Jasplakinolide treatment caused a dose-dependent increase in cell-cell fusion as measured by both syncytia and reporter gene assays, and latrunculin A treatment also resulted in fusion stimulation. Treatment with jasplakinolide or latrunculin A partially rescued a fusion pore opening defect caused by deletion of the PIV5 F protein cytoplasmic tail, but these drugs had no effect on fusion inhibited at earlier stages by either temperature arrest or by a PIV5 heptad repeat peptide. These data suggest that the cortical actin cytoskeleton is an important regulator of fusion pore enlargement, an energetically costly stage of viral fusion protein-mediated membrane merger.
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Affiliation(s)
- Mark A. Wurth
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington KY 40536
| | - Rachel M. Schowalter
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington KY 40536
| | - Everett Clinton Smith
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington KY 40536
| | - Carole L. Moncman
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington KY 40536
| | - Rebecca Ellis Dutch
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington KY 40536
| | - Richard O. McCann
- Mercer University School of Medicine, Division of Basic Medical Sciences, Macon, GA 31207
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