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Dobransky A, Root M, Hafner N, Marcum M, Sharifi HJ. CRL4-DCAF1 Ubiquitin Ligase Dependent Functions of HIV Viral Protein R and Viral Protein X. Viruses 2024; 16:1313. [PMID: 39205287 PMCID: PMC11360348 DOI: 10.3390/v16081313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2024] [Revised: 08/04/2024] [Accepted: 08/15/2024] [Indexed: 09/04/2024] Open
Abstract
The Human Immunodeficiency Virus (HIV) encodes several proteins that contort the host cell environment to promote viral replication and spread. This is often accomplished through the hijacking of cellular ubiquitin ligases. These reprogrammed complexes initiate or enhance the ubiquitination of cellular proteins that may otherwise act to restrain viral replication. Ubiquitination of target proteins may alter protein function or initiate proteasome-dependent destruction. HIV Viral Protein R (Vpr) and the related HIV-2 Viral Protein X (Vpx), engage the CRL4-DCAF1 ubiquitin ligase complex to target numerous cellular proteins. In this review we describe the CRL4-DCAF1 ubiquitin ligase complex and its interactions with HIV Vpr and Vpx. We additionally summarize the cellular proteins targeted by this association as well as the observed or hypothesized impact on HIV.
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Affiliation(s)
- Ashley Dobransky
- Department of Biological and Environmental Sciences, Le Moyne College, Syracuse, NY 13214, USA
| | - Mary Root
- Department of Biological and Environmental Sciences, Le Moyne College, Syracuse, NY 13214, USA
| | - Nicholas Hafner
- Department of Biological and Environmental Sciences, Le Moyne College, Syracuse, NY 13214, USA
| | - Matty Marcum
- Department of Biological and Environmental Sciences, Le Moyne College, Syracuse, NY 13214, USA
| | - H John Sharifi
- Department of Biological and Environmental Sciences, Le Moyne College, Syracuse, NY 13214, USA
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Vanegas-Torres CA, Schindler M. HIV-1 Vpr Functions in Primary CD4 + T Cells. Viruses 2024; 16:420. [PMID: 38543785 PMCID: PMC10975730 DOI: 10.3390/v16030420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Revised: 03/05/2024] [Accepted: 03/05/2024] [Indexed: 05/23/2024] Open
Abstract
HIV-1 encodes four accesory proteins in addition to its structural and regulatory genes. Uniquely amongst them, Vpr is abundantly present within virions, meaning it is poised to exert various biological effects on the host cell upon delivery. In this way, Vpr contributes towards the establishment of a successful infection, as evidenced by the extent to which HIV-1 depends on this factor to achieve full pathogenicity in vivo. Although HIV infects various cell types in the host organism, CD4+ T cells are preferentially targeted since they are highly permissive towards productive infection, concomitantly bringing about the hallmark immune dysfunction that accompanies HIV-1 spread. The last several decades have seen unprecedented progress in unraveling the activities Vpr possesses in the host cell at the molecular scale, increasingly underscoring the importance of this viral component. Nevertheless, it remains controversial whether some of these advances bear in vivo relevance, since commonly employed cellular models significantly differ from primary T lymphocytes. One prominent example is the "established" ability of Vpr to induce G2 cell cycle arrest, with enigmatic physiological relevance in infected primary T lymphocytes. The objective of this review is to present these discoveries in their biological context to illustrate the mechanisms whereby Vpr supports HIV-1 infection in CD4+ T cells, whilst identifying findings that require validation in physiologically relevant models.
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Affiliation(s)
| | - Michael Schindler
- Institute for Medical Virology and Epidemiology of Viral Diseases, University Hospital Tuebingen, 72076 Tuebingen, Germany;
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Woottum M, Yan S, Sayettat S, Grinberg S, Cathelin D, Bekaddour N, Herbeuval JP, Benichou S. Macrophages: Key Cellular Players in HIV Infection and Pathogenesis. Viruses 2024; 16:288. [PMID: 38400063 PMCID: PMC10893316 DOI: 10.3390/v16020288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 02/12/2024] [Accepted: 02/13/2024] [Indexed: 02/25/2024] Open
Abstract
Although cells of the myeloid lineages, including tissue macrophages and conventional dendritic cells, were rapidly recognized, in addition to CD4+ T lymphocytes, as target cells of HIV-1, their specific roles in the pathophysiology of infection were initially largely neglected. However, numerous studies performed over the past decade, both in vitro in cell culture systems and in vivo in monkey and humanized mouse animal models, led to growing evidence that macrophages play important direct and indirect roles as HIV-1 target cells and in pathogenesis. It has been recently proposed that macrophages are likely involved in all stages of HIV-1 pathogenesis, including virus transmission and dissemination, but above all, in viral persistence through the establishment, together with latently infected CD4+ T cells, of virus reservoirs in many host tissues, the major obstacle to virus eradication in people living with HIV. Infected macrophages are indeed found, very often as multinucleated giant cells expressing viral antigens, in almost all lymphoid and non-lymphoid tissues of HIV-1-infected patients, where they can probably persist for long period of time. In addition, macrophages also likely participate, directly as HIV-1 targets or indirectly as key regulators of innate immunity and inflammation, in the chronic inflammation and associated clinical disorders observed in people living with HIV, even in patients receiving effective antiretroviral therapy. The main objective of this review is therefore to summarize the recent findings, and also to revisit older data, regarding the critical functions of tissue macrophages in the pathophysiology of HIV-1 infection, both as major HIV-1-infected target cells likely found in almost all tissues, as well as regulators of innate immunity and inflammation during the different stages of HIV-1 pathogenesis.
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Affiliation(s)
- Marie Woottum
- Institut Cochin, Inserm U1016, CNRS UMR-8104, Université Paris Cité, 75014 Paris, France; (M.W.); (S.Y.); (S.S.)
| | - Sen Yan
- Institut Cochin, Inserm U1016, CNRS UMR-8104, Université Paris Cité, 75014 Paris, France; (M.W.); (S.Y.); (S.S.)
| | - Sophie Sayettat
- Institut Cochin, Inserm U1016, CNRS UMR-8104, Université Paris Cité, 75014 Paris, France; (M.W.); (S.Y.); (S.S.)
| | - Séverine Grinberg
- CNRS UMR-8601, Université Paris Cité, 75006 Paris, France; (S.G.); (D.C.); (N.B.); (J.-P.H.)
| | - Dominique Cathelin
- CNRS UMR-8601, Université Paris Cité, 75006 Paris, France; (S.G.); (D.C.); (N.B.); (J.-P.H.)
| | - Nassima Bekaddour
- CNRS UMR-8601, Université Paris Cité, 75006 Paris, France; (S.G.); (D.C.); (N.B.); (J.-P.H.)
| | - Jean-Philippe Herbeuval
- CNRS UMR-8601, Université Paris Cité, 75006 Paris, France; (S.G.); (D.C.); (N.B.); (J.-P.H.)
| | - Serge Benichou
- Institut Cochin, Inserm U1016, CNRS UMR-8104, Université Paris Cité, 75014 Paris, France; (M.W.); (S.Y.); (S.S.)
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4
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Williams ME, Williams AA, Naudé PJW. Viral protein R (Vpr)-induced neuroinflammation and its potential contribution to neuronal dysfunction: a scoping review. BMC Infect Dis 2023; 23:512. [PMID: 37545000 PMCID: PMC10405499 DOI: 10.1186/s12879-023-08495-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Accepted: 07/30/2023] [Indexed: 08/08/2023] Open
Abstract
HIV-associated neurocognitive disorders (HAND) are the result of the activity of HIV-1 within the central nervous system (CNS). While the introduction of antiretroviral therapy (ART) has significantly reduced the occurrence of severe cases of HAND, milder cases still persist. The persistence of HAND in the modern ART era has been linked to a chronic dysregulated inflammatory profile. There is increasing evidence suggesting a potential role of Viral protein R (Vpr) in dysregulating the neuroinflammatory processes in people living with HIV (PLHIV), which may contribute to the development of HAND. Since the role of Vpr in neuroinflammatory mechanisms has not been clearly defined, we conducted a scoping review of fundamental research studies on this topic. The review aimed to assess the size and scope of available research literature on this topic and provide commentary on whether Vpr contributes to neuroinflammation, as highlighted in fundamental studies. Based on the specified selection criteria, 10 studies (6 of which were cell culture-based and 4 that included both animal and cell culture experiments) were eligible for inclusion. The main findings were that (1) Vpr can increase neuroinflammatory markers, with studies consistently reporting higher levels of TNF-α and IL-8, (2) Vpr induces (neuro)inflammation via specific pathways, including the PI3K/AKT, p38-MAPk, JNK-SAPK and Sur1-Trpm4 channels in astrocytes and the p38 and JNK-SAPK in myeloid cells, and (3) Vpr-specific protein amino acid signatures (73R, 77R and 80A) may play an important role in exacerbating neuroinflammation and the neuropathophysiology of HAND. Therefore, Vpr should be investigated for its potential contribution to neuroinflammation in the development of HAND.
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Affiliation(s)
| | | | - Petrus J W Naudé
- Department of Psychiatry and Mental Health, University of Cape Town, Cape Town, South Africa
- Neuroscience Institute, University of Cape Town, Cape Town, South Africa
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Khan H, Sumner RP, Rasaiyaah J, Tan CP, Rodriguez-Plata MT, Van Tulleken C, Fink D, Zuliani-Alvarez L, Thorne L, Stirling D, Milne RSB, Towers GJ. HIV-1 Vpr antagonizes innate immune activation by targeting karyopherin-mediated NF-κB/IRF3 nuclear transport. eLife 2020; 9:e60821. [PMID: 33300875 PMCID: PMC7759385 DOI: 10.7554/elife.60821] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 12/09/2020] [Indexed: 12/13/2022] Open
Abstract
HIV-1 must replicate in cells that are equipped to defend themselves from infection through intracellular innate immune systems. HIV-1 evades innate immune sensing through encapsidated DNA synthesis and encodes accessory genes that antagonize specific antiviral effectors. Here, we show that both particle associated, and expressed HIV-1 Vpr, antagonize the stimulatory effect of a variety of pathogen associated molecular patterns by inhibiting IRF3 and NF-κB nuclear transport. Phosphorylation of IRF3 at S396, but not S386, was also inhibited. We propose that, rather than promoting HIV-1 nuclear import, Vpr interacts with karyopherins to disturb their import of IRF3 and NF-κB to promote replication in macrophages. Concordantly, we demonstrate Vpr-dependent rescue of HIV-1 replication in human macrophages from inhibition by cGAMP, the product of activated cGAS. We propose a model that unifies Vpr manipulation of nuclear import and inhibition of innate immune activation to promote HIV-1 replication and transmission.
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Affiliation(s)
- Hataf Khan
- Division of Infection and Immunity, University College LondonLondonUnited Kingdom
| | - Rebecca P Sumner
- Division of Infection and Immunity, University College LondonLondonUnited Kingdom
| | - Jane Rasaiyaah
- Division of Infection and Immunity, University College LondonLondonUnited Kingdom
| | - Choon Ping Tan
- Division of Infection and Immunity, University College LondonLondonUnited Kingdom
| | | | - Chris Van Tulleken
- Division of Infection and Immunity, University College LondonLondonUnited Kingdom
| | - Douglas Fink
- Division of Infection and Immunity, University College LondonLondonUnited Kingdom
| | | | - Lucy Thorne
- Division of Infection and Immunity, University College LondonLondonUnited Kingdom
| | - David Stirling
- Division of Infection and Immunity, University College LondonLondonUnited Kingdom
| | - Richard SB Milne
- Division of Infection and Immunity, University College LondonLondonUnited Kingdom
| | - Greg J Towers
- Division of Infection and Immunity, University College LondonLondonUnited Kingdom
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Lubow J, Collins KL. Vpr Is a VIP: HIV Vpr and Infected Macrophages Promote Viral Pathogenesis. Viruses 2020; 12:E809. [PMID: 32726944 PMCID: PMC7472745 DOI: 10.3390/v12080809] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 07/17/2020] [Accepted: 07/23/2020] [Indexed: 02/06/2023] Open
Abstract
HIV infects several cell types in the body, including CD4+ T cells and macrophages. Here we review the role of macrophages in HIV infection and describe complex interactions between viral proteins and host defenses in these cells. Macrophages exist in many forms throughout the body, where they play numerous roles in healthy and diseased states. They express pattern-recognition receptors (PRRs) that bind viral, bacterial, fungal, and parasitic pathogens, making them both a key player in innate immunity and a potential target of infection by pathogens, including HIV. Among these PRRs is mannose receptor, a macrophage-specific protein that binds oligosaccharides, restricts HIV replication, and is downregulated by the HIV accessory protein Vpr. Vpr significantly enhances infection in vivo, but the mechanism by which this occurs is controversial. It is well established that Vpr alters the expression of numerous host proteins by using its co-factor DCAF1, a component of the DCAF1-DDB1-CUL4 ubiquitin ligase complex. The host proteins targeted by Vpr and their role in viral replication are described in detail. We also discuss the structure and function of the viral protein Env, which is stabilized by Vpr in macrophages. Overall, this literature review provides an updated understanding of the contributions of macrophages and Vpr to HIV pathogenesis.
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Affiliation(s)
- Jay Lubow
- Department of Microbiology & Immunology, University of Michigan, Ann Arbor, MI 48109, USA;
| | - Kathleen L. Collins
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA
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Khan T, Mayuresh Patkar M, Momin M, Omri A. Macrophage targeted nanocarrier delivery systems in HIV therapeutics. Expert Opin Drug Deliv 2020; 17:903-918. [PMID: 32347124 DOI: 10.1080/17425247.2020.1762565] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
INTRODUCTION Human immunodeficiency virus (HIV) targets and modulates the immune system increasing the risk of other associated infections. Highly active antiretroviral therapy (HAART) has significantly improved AIDS-associated morbidity, but has limitations of adverse effects, frequent dosing regimen leading to medical non-adherence. Drug delivery systems that target HIV reservoirs could potentially reduce dose-dependent toxicity and the duration of treatment. The major cellular HIV reservoirs are macrophages and CD4+ T cells with macrophages being responsible for carrying and spreading the virus. The crucial involvement of macrophages in the pathogenesis of HIV infection has led to development of macrophage targeted nanocarrier delivery systems. AREAS COVERED Eradication of viral reservoirs like HIV-infected macrophages has emerged to be a fundamental barrier and challenge for complete eradication of HIV from the immune system. Literature reports several macrophage targeted nanocarrier delivery systems developed as either functionalized or non-functionalized formulations such as liposomes, ethosomes, polymeric nanoparticles, dendrimers, and solid lipid nanoparticles showcasing superior efficacy over the conventional antiretroviral delivery systems. EXPERT OPINION The development of fixed dose combination of antiretroviral drugs into macrophage targeted delivery systems should factor in the inherent plasticity and heterogeneity of macrophages that is dependent on their microenvironment. A rational selection of nanocarriers will facilitate selectivity and enhanced efficacy of antiretroviral drugs accompanied by reduced dosing and toxicity. Such macrophage targeted delivery systems would positively impact the therapeutic outcomes in the management of HIV infection.
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Affiliation(s)
- Tabassum Khan
- Department of Pharmaceutical Chemistry and Quality Assurance, SVKM's Dr. Bhanuben Nanavati College of Pharmacy , Mumbai, Maharashtra, India
| | - Mayuresh Mayuresh Patkar
- Department of Quality Assurance, SVKM's Dr. Bhanuben Nanavati College of Pharmacy , Mumbai, Maharashtra, India
| | - Munira Momin
- Department of Pharmaceutics, SVKM's Dr. Bhanuben Nanavati College of Pharmacy , Mumbai, Maharashtra, India
| | - Abdelwahab Omri
- The Novel Drug & Vaccine Delivery Systems Facility, Department of Chemistry and Biochemistry, Laurentian University , Sudbury, ON, Canada
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HIV-1 Accessory Protein Vpr Interacts with REAF/RPRD2 To Mitigate Its Antiviral Activity. J Virol 2020; 94:JVI.01591-19. [PMID: 31776272 DOI: 10.1128/jvi.01591-19] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 10/29/2019] [Indexed: 12/18/2022] Open
Abstract
The human immunodeficiency virus type 1 (HIV-1) accessory protein Vpr enhances viral replication in both macrophages and, to a lesser extent, cycling T cells. Virion-packaged Vpr is released in target cells shortly after entry, suggesting it is required in the early phase of infection. Previously, we described REAF (RNA-associated early-stage antiviral factor; RPRD2), a constitutively expressed protein that potently restricts HIV replication at or during reverse transcription. Here, we show that a virus without an intact vpr gene is more highly restricted by REAF and, using delivery by virus-like particles (VLPs), that Vpr alone is sufficient for REAF degradation in primary macrophages. REAF is more highly expressed in macrophages than in cycling T cells, and we detected, by coimmunoprecipitation assay, an interaction between Vpr protein and endogenous REAF. Vpr acts quickly during the early phase of replication and induces the degradation of REAF within 30 min of viral entry. Using Vpr F34I and Q65R viral mutants, we show that nuclear localization and interaction with cullin 4A-DBB1 (DCAF1) E3 ubiquitin ligase are required for REAF degradation by Vpr. In response to infection, cells upregulate REAF levels. This response is curtailed in the presence of Vpr. These findings support the hypothesis that Vpr induces the degradation of a factor, REAF, that impedes HIV infection in macrophages.IMPORTANCE For at least 30 years, it has been known that HIV-1 Vpr, a protein carried in the virion, is important for efficient infection of primary macrophages. Vpr is also a determinant of the pathogenic effects of HIV-1 in vivo A number of cellular proteins that interact with Vpr have been identified. So far, it has not been possible to associate these proteins with altered viral replication in macrophages or to explain why Vpr is carried in the virus particle. Here, we show that Vpr mitigates the antiviral effects of REAF, a protein highly expressed in primary macrophages and one that inhibits virus replication during reverse transcription. REAF is degraded by Vpr within 30 min of virus entry in a manner dependent on the nuclear localization of Vpr and its interaction with the cell's protein degradation machinery.
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Chang H, Siarot L, Matsuura R, Lo CW, Sato H, Otsuki H, Aida Y. Distinct MCM10 Proteasomal Degradation Profiles by Primate Lentiviruses Vpr Proteins. Viruses 2020; 12:v12010098. [PMID: 31952107 PMCID: PMC7019430 DOI: 10.3390/v12010098] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 12/28/2019] [Accepted: 01/10/2020] [Indexed: 12/24/2022] Open
Abstract
Viral protein R (Vpr) is an accessory protein found in various primate lentiviruses, including human immunodeficiency viruses type 1 and 2 (HIV-1 and HIV-2) as well as simian immunodeficiency viruses (SIVs). Vpr modulates many processes during viral lifecycle via interaction with several of cellular targets. Previous studies showed that HIV-1 Vpr strengthened degradation of Mini-chromosome Maintenance Protein10 (MCM10) by manipulating DCAF1-Cul4-E3 ligase in proteasome-dependent pathway. However, whether Vpr from other primate lentiviruses are also associated with MCM10 degradation and the ensuing impact remain unknown. Based on phylogenetic analyses, a panel of primate lentiviruses Vpr/x covering main virus lineages was prepared. Distinct MCM10 degradation profiles were mapped and HIV-1, SIVmus and SIVrcm Vprs induced MCM10 degradation in proteasome-dependent pathway. Colocalization and interaction between MCM10 with these Vprs were also observed. Moreover, MCM10 2-7 interaction region was identified as a determinant region susceptible to degradation. However, MCM10 degradation did not alleviate DNA damage response induced by these Vpr proteins. MCM10 degradation by HIV-1 Vpr proteins was correlated with G2/M arrest, while induction of apoptosis and oligomerization formation of Vpr failed to alter MCM10 proteolysis. The current study demonstrated a distinct interplay pattern between primate lentiviruses Vpr proteins and MCM10.
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Affiliation(s)
- Hao Chang
- Viral Infectious Diseases Unit, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- Laboratory of Viral Infectious Diseases, Department of Computational Biology and Medical Sciences, Graduate School of Frontier Science, The University of Tokyo, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- Photonics Control Technology Team, RIKEN Center for Advanced Photonics, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Lowela Siarot
- Viral Infectious Diseases Unit, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Ryosuke Matsuura
- Viral Infectious Diseases Unit, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- Laboratory of Viral Infectious Diseases, Department of Computational Biology and Medical Sciences, Graduate School of Frontier Science, The University of Tokyo, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Chieh-Wen Lo
- Viral Infectious Diseases Unit, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- Photonics Control Technology Team, RIKEN Center for Advanced Photonics, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- Laboratory of Global Animal Resource Science, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Hirotaka Sato
- Viral Infectious Diseases Unit, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- Nakamura Laboratory, Baton Zone program, Riken Cluster for Science, Technology and Innovation Hub, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Hiroyuki Otsuki
- Viral Infectious Diseases Unit, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Yoko Aida
- Viral Infectious Diseases Unit, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- Laboratory of Viral Infectious Diseases, Department of Computational Biology and Medical Sciences, Graduate School of Frontier Science, The University of Tokyo, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- Laboratory of Global Animal Resource Science, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- Nakamura Laboratory, Baton Zone program, Riken Cluster for Science, Technology and Innovation Hub, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- Correspondence:
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Vpr and Its Cellular Interaction Partners: R We There Yet? Cells 2019; 8:cells8111310. [PMID: 31652959 PMCID: PMC6912716 DOI: 10.3390/cells8111310] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 10/22/2019] [Accepted: 10/23/2019] [Indexed: 12/17/2022] Open
Abstract
Vpr is a lentiviral accessory protein that is expressed late during the infection cycle and is packaged in significant quantities into virus particles through a specific interaction with the P6 domain of the viral Gag precursor. Characterization of the physiologically relevant function(s) of Vpr has been hampered by the fact that in many cell lines, deletion of Vpr does not significantly affect viral fitness. However, Vpr is critical for virus replication in primary macrophages and for viral pathogenesis in vivo. It is generally accepted that Vpr does not have a specific enzymatic activity but functions as a molecular adapter to modulate viral or cellular processes for the benefit of the virus. Indeed, many Vpr interacting factors have been described by now, and the goal of this review is to summarize our current knowledge of cellular proteins targeted by Vpr.
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Wang Q, Su L. Vpr Enhances HIV-1 Env Processing and Virion Infectivity in Macrophages by Modulating TET2-Dependent IFITM3 Expression. mBio 2019; 10:e01344-19. [PMID: 31431548 PMCID: PMC6703422 DOI: 10.1128/mbio.01344-19] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 07/24/2019] [Indexed: 12/28/2022] Open
Abstract
HIV-1 Vpr enhances viral replication in human macrophages via multiple mechanisms that are not clearly defined. It does not affect HIV-1 virion production during the first round of infection. We have recently discovered that Vpr targets the DNA demethylase TET2 for degradation, which leads to sustained interleukin-6 (IL-6) expression and elevated HIV-1 replication. We report here that Vpr enhanced Env processing in infected macrophages, associated with increased Env incorporation into virions with higher infectivity. Interestingly, IFITM3 was constitutively expressed in macrophages in a TET2-dependent fashion. We showed that Vpr-enhanced Env processing depended genetically on TET2 and IFITM3. We further showed that Vpr reduced IFITM3 expression by reducing demethylation of the IFITM3 promoter in macrophages, associated with degradation of TET2 and reduced TET2 binding to the IFITIM3 promoter. Our findings indicate that the Vpr-TET2 axis enhances HIV-1 replication in macrophages via two independent mechanisms: reduced IFTIM3 expression to enhance Env processing and virion infectivity and sustained IL-6 expression to increase HIV-1 replication. The Vpr-TET2 axis may provide a novel target to develop therapeutics to inhibit HIV-1 infection and pathogenesis.IMPORTANCE How Vpr enhances HIV-1 replication in macrophages is still unclear. We report here that Vpr enhanced HIV-1 Env processing during the first round of HIV-1 replication, resulting in virions with higher Env incorporation and viral infectivity. These higher-quality viral particles contributed to elevated infection during the second round and spreading infection in macrophages and other HIV-1 target cells. We have recently discovered that TET2 is a novel host factor degraded by Vpr, which leads to sustained IL-6 expression in macrophages. Interestingly, Vpr-enhanced HIV-1 Env processing depended on both the IFITIM3 and TET2 genes. The constitutive expression of IFITIM3 expression in macrophages was maintained by TET2, which demethylated the IFITIM3 promoter. We conclude that the Vpr degrades TET2 to enhance HIV-1 replication in macrophages by reducing IFITIM3 expression to increase viral Env processing, virion incorporation, and infectivity and by sustaining IL-6 expression to increase HIV-1 gene expression. The Vpr-TET2 axis may serve as a novel target to develop anti-HIV drugs to inhibit HIV-1 infection and pathogenesis.
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Affiliation(s)
- Qi Wang
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Department of Microbiology & Immunology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Lishan Su
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Department of Microbiology & Immunology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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Virion-Associated Vpr Alleviates a Postintegration Block to HIV-1 Infection of Dendritic Cells. J Virol 2017; 91:JVI.00051-17. [PMID: 28424288 DOI: 10.1128/jvi.00051-17] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Accepted: 04/16/2017] [Indexed: 01/23/2023] Open
Abstract
Viral protein R (Vpr) is an HIV-1 accessory protein whose function remains poorly understood. In this report, we sought to determine the requirement of Vpr for facilitating HIV-1 infection of monocyte-derived dendritic cells (MDDCs), one of the first cell types to encounter virus in the peripheral mucosal tissues. In this report, we characterize a significant restriction of Vpr-deficient virus replication and spread in MDDCs alone and in cell-to-cell spread in MDDC-CD4+ T cell cocultures. This restriction of HIV-1 replication in MDDCs was observed in a single round of virus replication and was rescued by the expression of Vpr in trans in the incoming virion. Interestingly, infections of MDDCs with viruses that encode Vpr mutants unable to interact with either the DCAF1/DDB1 E3 ubiquitin ligase complex or a host factor hypothesized to be targeted for degradation by Vpr also displayed a significant replication defect. While the extent of proviral integration in HIV-1-infected MDDCs was unaffected by the absence of Vpr, the transcriptional activity of the viral long terminal repeat (LTR) from Vpr-deficient proviruses was significantly reduced. Together, these results characterize a novel postintegration restriction of HIV-1 replication in MDDCs and show that the interaction of Vpr with the DCAF1/DDB1 E3 ubiquitin ligase complex and the yet-to-be-identified host factor might alleviate this restriction by inducing transcription from the viral LTR. Taken together, these findings identify a robust in vitro cell culture system that is amenable to addressing mechanisms underlying Vpr-mediated enhancement of HIV-1 replication.IMPORTANCE Despite decades of work, the function of the HIV-1 protein Vpr remains poorly understood, primarily due to the lack of an in vitro cell culture system that demonstrates a deficit in replication upon infection with viruses in the absence of Vpr. In this report, we describe a novel cell infection system that utilizes primary human dendritic cells, which display a robust decrease in viral replication upon infection with Vpr-deficient HIV-1. We show that this replication difference occurs in a single round of infection and is due to decreased transcriptional output from the integrated viral genome. Viral transcription could be rescued by virion-associated Vpr. Using mutational analysis, we show that domains of Vpr involved in binding to the DCAF1/DDB1/E3 ubiquitin ligase complex and prevention of cell cycle progression into mitosis are required for LTR-mediated viral expression, suggesting that the evolutionarily conserved G2 cell cycle arrest function of Vpr is essential for HIV-1 replication.
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13
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Staitieh BS, Egea EE, Guidot DM. Pulmonary Innate Immune Dysfunction in Human Immunodeficiency Virus. Am J Respir Cell Mol Biol 2017; 56:563-567. [PMID: 27911588 PMCID: PMC5449488 DOI: 10.1165/rcmb.2016-0213tr] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 11/30/2016] [Indexed: 12/18/2022] Open
Abstract
The advent of antiretroviral therapy has transformed infection by the type 1 human immunodeficiency virus (HIV) from a rapidly fatal disease to a chronic illness with excellent long-term survival rates. Although HIV primarily targets the adaptive arm of host immunity, it simultaneously impacts the innate immune system, and has profound implications for lung health, even when viral suppression is achieved with antiretroviral therapy. The lung has evolved a unique array of innate immune defenses, and the pathophysiological interactions between HIV and the pulmonary innate immune system deserve particular attention. In this review, we discuss work that elucidates how the components of innate immunity both respond to and are perturbed by infection with HIV.
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Affiliation(s)
- Bashar S. Staitieh
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Emory University School of Medicine, Atlanta, Georgia; and
| | - Eduardo E. Egea
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Emory University School of Medicine, Atlanta, Georgia; and
| | - David M. Guidot
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Emory University School of Medicine, Atlanta, Georgia; and
- the Atlanta Veterans Administration Medical Center, Decatur, Georgia
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14
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González ME. The HIV-1 Vpr Protein: A Multifaceted Target for Therapeutic Intervention. Int J Mol Sci 2017; 18:ijms18010126. [PMID: 28075409 PMCID: PMC5297760 DOI: 10.3390/ijms18010126] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 12/22/2016] [Accepted: 01/03/2017] [Indexed: 12/16/2022] Open
Abstract
The human immunodeficiency virus type 1 (HIV-1) Vpr protein is an attractive target for antiretroviral drug development. The conservation both of the structure along virus evolution and the amino acid sequence in viral isolates from patients underlines the importance of Vpr for the establishment and progression of HIV-1 disease. While its contribution to virus replication in dividing and non-dividing cells and to the pathogenesis of HIV-1 in many different cell types, both extracellular and intracellular forms, have been extensively studied, its precise mechanism of action nevertheless remains enigmatic. The present review discusses how the apparently multifaceted interplay between Vpr and host cells may be due to the impairment of basic metabolic pathways. Vpr protein modifies host cell energy metabolism, oxidative status, and proteasome function, all of which are likely conditioned by the concentration and multimerization of the protein. The characterization of Vpr domains along with new laboratory tools for the assessment of their function has become increasingly relevant in recent years. With these advances, it is conceivable that drug discovery efforts involving Vpr-targeted antiretrovirals will experience substantial growth in the coming years.
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Affiliation(s)
- María Eugenia González
- Unidad de Expresión Viral, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Carretera de Majadahonda-Pozuelo Km 2, Majadahonda, 28220 Madrid, Spain.
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15
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Abstract
The HIV genome encodes a small number of viral proteins (i.e., 16), invariably establishing cooperative associations among HIV proteins and between HIV and host proteins, to invade host cells and hijack their internal machineries. As a known example, the HIV envelope glycoprotein GP120 is closely associated with GP41 for viral entry. From a genome-wide perspective, a hypothesis can be worked out to determine whether 16 HIV proteins could develop 120 possible pairwise associations either by physical interactions or by functional associations mediated via HIV or host molecules. Here, we present the first systematic review of experimental evidence on HIV genome-wide protein associations using a large body of publications accumulated over the past 3 decades. Of 120 possible pairwise associations between 16 HIV proteins, at least 34 physical interactions and 17 functional associations have been identified. To achieve efficient viral replication and infection, HIV protein associations play essential roles (e.g., cleavage, inhibition, and activation) during the HIV life cycle. In either a dispensable or an indispensable manner, each HIV protein collaborates with another viral protein to accomplish specific activities that precisely take place at the proper stages of the HIV life cycle. In addition, HIV genome-wide protein associations have an impact on anti-HIV inhibitors due to the extensive cross talk between drug-inhibited proteins and other HIV proteins. Overall, this study presents for the first time a comprehensive overview of HIV genome-wide protein associations, highlighting meticulous collaborations between all viral proteins during the HIV life cycle.
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Affiliation(s)
- Guangdi Li
- Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center, Key Laboratory of Diabetes Immunology, Ministry of Education, National Clinical Research Center for Metabolic Diseases, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China KU Leuven-University of Leuven, Rega Institute for Medical Research, Department of Microbiology and Immunology, Leuven, Belgium
| | - Erik De Clercq
- KU Leuven-University of Leuven, Rega Institute for Medical Research, Department of Microbiology and Immunology, Leuven, Belgium
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16
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Rossenkhan R, MacLeod IJ, Brumme ZL, Magaret CA, Sebunya TK, Musonda R, Gashe BA, Edlefsen PT, Novitsky V, Essex M. Transmitted/Founder HIV-1 Subtype C Viruses Show Distinctive Signature Patterns in Vif, Vpr, and Vpu That Are Under Subsequent Immune Pressure During Early Infection. AIDS Res Hum Retroviruses 2016; 32:1031-1045. [PMID: 27349335 DOI: 10.1089/aid.2015.0330] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Viral variants that predominate during early infection may exhibit constrained diversity compared with those found during chronic infection and could contain amino acid signature patterns that may enhance transmission, establish productive infection, and influence early events that modulate the infection course. We compared amino acid distributions in 17 patients recently infected with HIV-1C with patients with chronic infection. We found significantly lower entropy in inferred transmitted/founder (t/f) compared with chronic viruses and identified signature patterns in Vif and Vpr from inferred t/f viruses. We investigated sequence evolution longitudinally up to 500 days postseroconversion and compared the impact of selected substitutions on predicted human leukocyte antigen (HLA) binding affinities of published and predicted cytotoxic T-lymphocyte epitopes. Polymorphisms in Vif and Vpr during early infection occurred more frequently at epitope-HLA anchor residues and significantly decreased predicted epitope-HLA binding. Transmission-associated sequence signatures may have implications for novel strategies to prevent HIV-1 transmission.
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Affiliation(s)
- Raabya Rossenkhan
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts
- Botswana Harvard AIDS Institute, Gaborone, Botswana
- Department of Biological Sciences, University of Botswana, Gaborone, Botswana
- Vaccine and Infectious Diseases Division, Fred Hutchinson Cancer Research Center, Seattle, Washington
| | - Iain J. MacLeod
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts
- Botswana Harvard AIDS Institute, Gaborone, Botswana
| | - Zabrina L. Brumme
- Faculty of Health Sciences, Simon Fraser University, Burnaby, Canada
- British Columbia Centre for Excellence in HIV/AIDS, Vancouver, Canada
| | - Craig A. Magaret
- Vaccine and Infectious Diseases Division, Fred Hutchinson Cancer Research Center, Seattle, Washington
| | - Theresa K. Sebunya
- Department of Biological Sciences, University of Botswana, Gaborone, Botswana
| | - Rosemary Musonda
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts
- Botswana Harvard AIDS Institute, Gaborone, Botswana
| | - Berhanu A. Gashe
- Department of Biological Sciences, University of Botswana, Gaborone, Botswana
| | - Paul T. Edlefsen
- Vaccine and Infectious Diseases Division, Fred Hutchinson Cancer Research Center, Seattle, Washington
| | - Vlad Novitsky
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts
- Botswana Harvard AIDS Institute, Gaborone, Botswana
| | - M. Essex
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts
- Botswana Harvard AIDS Institute, Gaborone, Botswana
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17
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HIV Genome-Wide Protein Associations: a Review of 30 Years of Research. Microbiol Mol Biol Rev 2016; 80:679-731. [PMID: 27357278 DOI: 10.1128/mmbr.00065-15] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The HIV genome encodes a small number of viral proteins (i.e., 16), invariably establishing cooperative associations among HIV proteins and between HIV and host proteins, to invade host cells and hijack their internal machineries. As a known example, the HIV envelope glycoprotein GP120 is closely associated with GP41 for viral entry. From a genome-wide perspective, a hypothesis can be worked out to determine whether 16 HIV proteins could develop 120 possible pairwise associations either by physical interactions or by functional associations mediated via HIV or host molecules. Here, we present the first systematic review of experimental evidence on HIV genome-wide protein associations using a large body of publications accumulated over the past 3 decades. Of 120 possible pairwise associations between 16 HIV proteins, at least 34 physical interactions and 17 functional associations have been identified. To achieve efficient viral replication and infection, HIV protein associations play essential roles (e.g., cleavage, inhibition, and activation) during the HIV life cycle. In either a dispensable or an indispensable manner, each HIV protein collaborates with another viral protein to accomplish specific activities that precisely take place at the proper stages of the HIV life cycle. In addition, HIV genome-wide protein associations have an impact on anti-HIV inhibitors due to the extensive cross talk between drug-inhibited proteins and other HIV proteins. Overall, this study presents for the first time a comprehensive overview of HIV genome-wide protein associations, highlighting meticulous collaborations between all viral proteins during the HIV life cycle.
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18
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Datta PK, Deshmane S, Khalili K, Merali S, Gordon JC, Fecchio C, Barrero CA. Glutamate metabolism in HIV-1 infected macrophages: Role of HIV-1 Vpr. Cell Cycle 2016; 15:2288-98. [PMID: 27245560 DOI: 10.1080/15384101.2016.1190054] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
HIV-1 infected macrophages play a significant role in the neuropathogenesis of AIDS. HIV-1 viral protein R (Vpr) not only facilitates HIV-1 infection but also contribute to long-lived persistence in macrophages. Our previous studies using SILAC-based proteomic analysis showed that the expression of critical metabolic enzymes in the glycolytic pathway and tricarboxylic acid (TCA) cycle were altered in response to Vpr expression in macrophages. We hypothesized that Vpr-induced modulation of glycolysis and TCA cycle regulates glutamate metabolism and release in HIV-1 infected macrophages. We assessed the amount of specific metabolites induced by Vpr and HIV-1 in macrophages at the intracellular and extracellular level in a time-dependent manner utilizing multiple reaction monitoring (MRM) targeted metabolomics. In addition, stable isotope-labeled glucose and an MRM targeted metabolomics assay were used to evaluate the de novo synthesis and release of glutamate in Vpr overexpressing macrophages and HIV-1 infected macrophages, throughout the metabolic flux of glycolytic pathway and TCA cycle activation. The metabolic flux studies demonstrated an increase in glucose uptake, glutamate release and accumulation of α-ketoglutarate (α-KG) and glutamine in the extracellular milieu in Vpr expressing and HIV-1 infected macrophages. Interestingly, glutamate pools and other intracellular intermediates (glucose-6-phosphate (G6P), fructose-6-phosphate (F6P), citrate, malate, α-KG, and glutamine) showed a decreased trend except for fumarate, in contrast to the glutamine accumulation observed in the extracellular space in Vpr overexpressing macrophages. Our studies demonstrate that dysregulation of mitochondrial glutamate metabolism induced by Vpr in HIV-1 infected macrophages commonly seen, may contribute to neurodegeneration via excitotoxic mechanisms in the context of NeuroAIDS.
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Affiliation(s)
- Prasun K Datta
- a Department of Neuroscience and Comprehensive NeuroAIDS Center , Lewis Katz School of Medicine at Temple University , Philadelphia , PA , USA
| | - Satish Deshmane
- a Department of Neuroscience and Comprehensive NeuroAIDS Center , Lewis Katz School of Medicine at Temple University , Philadelphia , PA , USA
| | - Kamel Khalili
- a Department of Neuroscience and Comprehensive NeuroAIDS Center , Lewis Katz School of Medicine at Temple University , Philadelphia , PA , USA
| | - Salim Merali
- a Department of Neuroscience and Comprehensive NeuroAIDS Center , Lewis Katz School of Medicine at Temple University , Philadelphia , PA , USA.,b Department of Pharmaceutical Sciences and Moulder Center for Drug Discovery Research , Temple University School of Pharmacy , Philadelphia , PA , USA
| | - John C Gordon
- b Department of Pharmaceutical Sciences and Moulder Center for Drug Discovery Research , Temple University School of Pharmacy , Philadelphia , PA , USA
| | - Chiara Fecchio
- b Department of Pharmaceutical Sciences and Moulder Center for Drug Discovery Research , Temple University School of Pharmacy , Philadelphia , PA , USA
| | - Carlos A Barrero
- a Department of Neuroscience and Comprehensive NeuroAIDS Center , Lewis Katz School of Medicine at Temple University , Philadelphia , PA , USA.,b Department of Pharmaceutical Sciences and Moulder Center for Drug Discovery Research , Temple University School of Pharmacy , Philadelphia , PA , USA
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19
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Abstract
ATR (Ataxia Telangiectasia and Rad3-related) is a member of the Phosphatidylinositol 3-kinase-related kinases (PIKKs) family, amongst six other vertebrate proteins known so far. ATR is indispensable for cell survival and its essential role is in sensing DNA damage and initiating appropriate repair responses. In this review we highlight emerging and recent observations connecting ATR to alternative roles in controlling the nuclear envelope, nucleolus, centrosome and other organelles in response to both internal and external stress conditions. We propose that ATR functions control cell plasticity by sensing structural deformations of different cellular components, including DNA and initiating appropriate repair responses, most of which are yet to be understood completely.
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Affiliation(s)
- Gururaj Rao Kidiyoor
- Istituto FIRC di Oncologia Molecolare, Milan, Italy; University of Milan, Milan, Italy
| | - Amit Kumar
- Developmental Toxicology Laboratory, Systems Toxicology and Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research, M.G. Marg, Lucknow 226001, India; Academy of Scientific and Innovative Research (AcSIR), India
| | - Marco Foiani
- Istituto FIRC di Oncologia Molecolare, Milan, Italy; University of Milan, Milan, Italy.
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20
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Abstract
Viruses often interfere with the DNA damage response to better replicate in their hosts. The human immunodeficiency virus 1 (HIV-1) viral protein R (Vpr) protein has been reported to modulate the activity of the DNA repair structure-specific endonuclease subunit (SLX4) complex and to promote cell cycle arrest. Vpr also interferes with the base-excision repair pathway by antagonizing the uracil DNA glycosylase (Ung2) enzyme. Using an unbiased quantitative proteomic screen, we report that Vpr down-regulates helicase-like transcription factor (HLTF), a DNA translocase involved in the repair of damaged replication forks. Vpr subverts the DDB1-cullin4-associated-factor 1 (DCAF1) adaptor of the Cul4A ubiquitin ligase to trigger proteasomal degradation of HLTF. This event takes place rapidly after Vpr delivery to cells, before and independently of Vpr-mediated G2 arrest. HLTF is degraded in lymphocytic cells and macrophages infected with Vpr-expressing HIV-1. Our results reveal a previously unidentified strategy for HIV-1 to antagonize DNA repair in host cells.
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21
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Charles TP, Shellito JE. Human Immunodeficiency Virus Infection and Host Defense in the Lungs. Semin Respir Crit Care Med 2016; 37:147-56. [PMID: 26974294 DOI: 10.1055/s-0036-1572553] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Immunosuppression associated with human immunodeficiency virus (HIV) infection impacts all components of host defense against pulmonary infection. Cells within the lung have altered immune function and are important reservoirs for HIV infection. The host immune response to infected lung cells further compromises responses to a secondary pathogenic insult. In the upper respiratory tract, mucociliary function is impaired and there are decreased levels of salivary immunoglobulin A. Host defenses in the lower respiratory tract are controlled by alveolar macrophages, lymphocytes, and polymorphonuclear leukocytes. As HIV infection progresses, lung CD4 T cells are reduced in number causing a lack of activation signals from CD4 T cells and impaired defense by macrophages. CD8 T cells, on the other hand, are increased in number and cause lymphocytic alveolitis. Specific antibody responses by B-lymphocytes are decreased and opsonization of microorganisms is impaired. These observed defects in host defense of the respiratory tract explain the susceptibility of HIV-infected persons for oropharyngeal candidiasis, bacterial pneumonia, Pneumocystis pneumonia, and other opportunistic infections.
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Affiliation(s)
- Tysheena P Charles
- Section of Pulmonary/Critical Care & Allergy/Immunology, Department of Medicine, Louisiana State University Health Sciences Center, New Orleans, Louisiana
| | - Judd E Shellito
- Section of Pulmonary/Critical Care & Allergy/Immunology, Department of Medicine, Louisiana State University Health Sciences Center, New Orleans, Louisiana
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22
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Dumas A, Lê-Bury G, Marie-Anaïs F, Herit F, Mazzolini J, Guilbert T, Bourdoncle P, Russell DG, Benichou S, Zahraoui A, Niedergang F. The HIV-1 protein Vpr impairs phagosome maturation by controlling microtubule-dependent trafficking. J Cell Biol 2016; 211:359-72. [PMID: 26504171 PMCID: PMC4621833 DOI: 10.1083/jcb.201503124] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The HIV protein Vpr interacts with EB1, p150Glued, and dynein heavy chain and perturbs the centripetal movement of phagosomes and their maturation, resulting in impaired phagolysosome biogenesis, which is important for bacterial clearance and cytokine production. Human immunodeficiency virus type 1 (HIV-1) impairs major functions of macrophages but the molecular basis for this defect remains poorly characterized. Here, we show that macrophages infected with HIV-1 were unable to respond efficiently to phagocytic triggers and to clear bacteria. The maturation of phagosomes, defined by the presence of late endocytic markers, hydrolases, and reactive oxygen species, was perturbed in HIV-1–infected macrophages. We showed that maturation arrest occurred at the level of the EHD3/MICAL-L1 endosomal sorting machinery. Unexpectedly, we found that the regulatory viral protein (Vpr) was crucial to perturb phagosome maturation. Our data reveal that Vpr interacted with EB1, p150Glued, and dynein heavy chain and was sufficient to critically alter the microtubule plus end localization of EB1 and p150Glued, hence altering the centripetal movement of phagosomes and their maturation. Thus, we identify Vpr as a modulator of the microtubule-dependent endocytic trafficking in HIV-1–infected macrophages, leading to strong alterations in phagolysosome biogenesis.
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Affiliation(s)
- Audrey Dumas
- Institut National de la Santé et de la Recherche Médicale U1016, Institut Cochin, Paris, France Centre National de la Recherche Scientifique UMR 8104, Paris, France Université Paris Descartes, Sorbonne Paris Cité, 75006 Paris, France
| | - Gabrielle Lê-Bury
- Institut National de la Santé et de la Recherche Médicale U1016, Institut Cochin, Paris, France Centre National de la Recherche Scientifique UMR 8104, Paris, France Université Paris Descartes, Sorbonne Paris Cité, 75006 Paris, France
| | - Florence Marie-Anaïs
- Institut National de la Santé et de la Recherche Médicale U1016, Institut Cochin, Paris, France Centre National de la Recherche Scientifique UMR 8104, Paris, France Université Paris Descartes, Sorbonne Paris Cité, 75006 Paris, France
| | - Floriane Herit
- Institut National de la Santé et de la Recherche Médicale U1016, Institut Cochin, Paris, France Centre National de la Recherche Scientifique UMR 8104, Paris, France Université Paris Descartes, Sorbonne Paris Cité, 75006 Paris, France
| | - Julie Mazzolini
- Institut National de la Santé et de la Recherche Médicale U1016, Institut Cochin, Paris, France Centre National de la Recherche Scientifique UMR 8104, Paris, France Université Paris Descartes, Sorbonne Paris Cité, 75006 Paris, France
| | - Thomas Guilbert
- Institut National de la Santé et de la Recherche Médicale U1016, Institut Cochin, Paris, France Centre National de la Recherche Scientifique UMR 8104, Paris, France Université Paris Descartes, Sorbonne Paris Cité, 75006 Paris, France
| | - Pierre Bourdoncle
- Institut National de la Santé et de la Recherche Médicale U1016, Institut Cochin, Paris, France Centre National de la Recherche Scientifique UMR 8104, Paris, France Université Paris Descartes, Sorbonne Paris Cité, 75006 Paris, France
| | - David G Russell
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853
| | - Serge Benichou
- Institut National de la Santé et de la Recherche Médicale U1016, Institut Cochin, Paris, France Centre National de la Recherche Scientifique UMR 8104, Paris, France Université Paris Descartes, Sorbonne Paris Cité, 75006 Paris, France
| | - Ahmed Zahraoui
- Institut National de la Santé et de la Recherche Médicale U1016, Institut Cochin, Paris, France Centre National de la Recherche Scientifique UMR 8104, Paris, France Université Paris Descartes, Sorbonne Paris Cité, 75006 Paris, France
| | - Florence Niedergang
- Institut National de la Santé et de la Recherche Médicale U1016, Institut Cochin, Paris, France Centre National de la Recherche Scientifique UMR 8104, Paris, France Université Paris Descartes, Sorbonne Paris Cité, 75006 Paris, France
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Desai TM, Marin M, Sood C, Shi J, Nawaz F, Aiken C, Melikyan GB. Fluorescent protein-tagged Vpr dissociates from HIV-1 core after viral fusion and rapidly enters the cell nucleus. Retrovirology 2015; 12:88. [PMID: 26511606 PMCID: PMC4625717 DOI: 10.1186/s12977-015-0215-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Accepted: 10/16/2015] [Indexed: 02/06/2023] Open
Abstract
Background HIV-1 Vpr is recruited into virions during assembly and appears to remain associated with the viral core after the reverse transcription and uncoating steps of entry. This feature has prompted the use of fluorescently labeled Vpr to visualize viral particles and to follow trafficking of post-fusion HIV-1 cores in the cytoplasm. Results Here, we tracked single pseudovirus entry and fusion and observed that fluorescently tagged Vpr gradually dissociates from post-fusion viral cores over the course of several minutes and accumulates in the nucleus. Kinetics measurements showed that fluorescent Vpr released from the cores very rapidly entered the cell nucleus. More than 10,000 Vpr molecules can be delivered into the cell nucleus within 45 min of infection by HIV-1 particles pseudotyped with the avian sarcoma and leukosis virus envelope glycoprotein. The fraction of Vpr from cell-bound viruses that accumulated in the nucleus was proportional to the extent of virus-cell fusion and was fully blocked by viral fusion inhibitors. Entry of virus-derived Vpr into the nucleus occurred independently of envelope glycoproteins or target cells. Fluorescence correlation spectroscopy revealed two forms of nuclear Vpr—monomers and very large complexes, likely involving host factors. The kinetics of viral Vpr entering the nucleus after fusion was not affected by point mutations in the capsid protein that alter the stability of the viral core. Conclusions The independence of Vpr shedding of capsid stability and its relatively rapid dissociation from post-fusion cores suggest that this process may precede capsid uncoating, which appears to occur on a slower time scale. Our results thus demonstrate that a bulk of fluorescently labeled Vpr incorporated into HIV-1 particles is released shortly after fusion. Future studies will address the question whether the quick and efficient nuclear delivery of Vpr derived from incoming viruses can regulate subsequent steps of HIV-1 infection. Electronic supplementary material The online version of this article (doi:10.1186/s12977-015-0215-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Tanay M Desai
- Division of Pediatric Infectious Diseases, Emory University School of Medicine, Atlanta, GA, USA.
| | - Mariana Marin
- Division of Pediatric Infectious Diseases, Emory University School of Medicine, Atlanta, GA, USA.
| | - Chetan Sood
- Division of Pediatric Infectious Diseases, Emory University School of Medicine, Atlanta, GA, USA.
| | - Jiong Shi
- Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville, TN, 37232, USA.
| | - Fatima Nawaz
- Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville, TN, 37232, USA.
| | - Christopher Aiken
- Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville, TN, 37232, USA.
| | - Gregory B Melikyan
- Division of Pediatric Infectious Diseases, Emory University School of Medicine, Atlanta, GA, USA. .,Children's Healthcare of Atlanta, Atlanta, GA, USA.
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24
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Vpr Enhances Tumor Necrosis Factor Production by HIV-1-Infected T Cells. J Virol 2015; 89:12118-30. [PMID: 26401039 DOI: 10.1128/jvi.02098-15] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Accepted: 09/16/2015] [Indexed: 02/06/2023] Open
Abstract
UNLABELLED The HIV-1 accessory protein Vpr displays different activities potentially impacting viral replication, including the arrest of the cell cycle in the G2 phase and the stimulation of apoptosis and DNA damage response pathways. Vpr also modulates cytokine production by infected cells, but this property remains partly characterized. Here, we investigated the effect of Vpr on the production of the proinflammatory cytokine tumor necrosis factor (TNF). We report that Vpr significantly increases TNF secretion by infected lymphocytes. De novo production of Vpr is required for this effect. Vpr mutants known to be defective for G2 cell cycle arrest induce lower levels of TNF secretion, suggesting a link between these two functions. Silencing experiments and the use of chemical inhibitors further implicated the cellular proteins DDB1 and TAK1 in this activity of Vpr. TNF secreted by HIV-1-infected cells triggers NF-κB activity in bystander cells and allows viral reactivation in a model of latently infected cells. Thus, the stimulation of the proinflammatory pathway by Vpr may impact HIV-1 replication in vivo. IMPORTANCE The role of the HIV-1 accessory protein Vpr remains only partially characterized. This protein is important for viral pathogenesis in infected individuals but is dispensable for viral replication in most cell culture systems. Some of the functions described for Vpr remain controversial. In particular, it remains unclear whether Vpr promotes or instead prevents proinflammatory and antiviral immune responses. In this report, we show that Vpr promotes the release of TNF, a proinflammatory cytokine associated with rapid disease progression. Using Vpr mutants or inhibiting selected cellular genes, we show that the cellular proteins DDB1 and TAK1 are involved in the release of TNF by HIV-infected cells. This report provides novel insights into how Vpr manipulates TNF production and helps clarify the role of Vpr in innate immune responses and inflammation.
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25
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Blondot ML, Dragin L, Lahouassa H, Margottin-Goguet F. How SLX4 cuts through the mystery of HIV-1 Vpr-mediated cell cycle arrest. Retrovirology 2014; 11:117. [PMID: 25496524 PMCID: PMC4271344 DOI: 10.1186/s12977-014-0117-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Accepted: 11/27/2014] [Indexed: 01/16/2023] Open
Abstract
Vpr is one of the most enigmatic viral auxiliary proteins of HIV. During the past twenty years, several activities have been ascribed to this viral protein, but one, its ability to mediate cell cycle arrest at the G2 to M transition has been the most extensively studied. Nonetheless, the genuine role of Vpr and its pathophysiological relevance in the viral life cycle have remained mysterious. Recent work by Laguette et al. (Cell 156:134-145, 2014) provides important insight into the molecular mechanism of Vpr-mediated G2 arrest. This study highlights for the first time how Vpr recruits the SLX4 endonuclease complex and how Vpr-induced inappropriate activation of this complex leads to G2 arrest. Here, we will discuss these findings in the light of previous work to show how they change the view of Vpr’s mechanism of action. We will also discuss how these findings open new questions towards the understanding of the biological function of Vpr regarding innate immune sensing.
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Affiliation(s)
- Marie-Lise Blondot
- Inserm, U1016, Institut Cochin, Paris, France. .,Cnrs, UMR8104, Paris, France. .,Université Paris Descartes, Sorbonne Paris Cité, France.
| | - Loic Dragin
- Inserm, U1016, Institut Cochin, Paris, France. .,Cnrs, UMR8104, Paris, France. .,Université Paris Descartes, Sorbonne Paris Cité, France.
| | - Hichem Lahouassa
- Inserm, U1016, Institut Cochin, Paris, France. .,Cnrs, UMR8104, Paris, France. .,Université Paris Descartes, Sorbonne Paris Cité, France.
| | - Florence Margottin-Goguet
- Inserm, U1016, Institut Cochin, Paris, France. .,Cnrs, UMR8104, Paris, France. .,Université Paris Descartes, Sorbonne Paris Cité, France.
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Le Sage V, Mouland AJ, Valiente-Echeverría F. Roles of HIV-1 capsid in viral replication and immune evasion. Virus Res 2014; 193:116-29. [PMID: 25036886 DOI: 10.1016/j.virusres.2014.07.010] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Revised: 07/04/2014] [Accepted: 07/07/2014] [Indexed: 02/07/2023]
Abstract
The primary roles of the human immunodeficiency virus type 1 (HIV-1) capsid (CA) protein are to encapsidate and protect the viral RNA genome. It is becoming increasing apparent that HIV-1 CA is a multifunctional protein that acts early during infection to coordinate uncoating, reverse transcription, nuclear import of the pre-integration complex and integration of double stranded viral DNA into the host genome. Additionally, numerous recent studies indicate that CA is playing a crucial function in HIV-1 immune evasion. Here we summarize the current knowledge on HIV-1 CA and its interactions with the host cell to promote infection. The fact that CA engages in a number of different protein-protein interactions with the host makes it an interesting target for the development of new potent antiviral agents.
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Affiliation(s)
- Valerie Le Sage
- HIV-1 RNA Trafficking Laboratory, Lady Davis Institute, Jewish General Hospital, Montréal, Québec H3T1E2, Canada; Department of Medicine, Division of Experimental Medicine, McGill University, Montréal, Québec H3A 1A3, Canada
| | - Andrew J Mouland
- HIV-1 RNA Trafficking Laboratory, Lady Davis Institute, Jewish General Hospital, Montréal, Québec H3T1E2, Canada; Department of Medicine, Division of Experimental Medicine, McGill University, Montréal, Québec H3A 1A3, Canada; Department of Microbiology and Immunology, McGill University, Montréal, Québec, H3A2B4, Canada
| | - Fernando Valiente-Echeverría
- HIV-1 RNA Trafficking Laboratory, Lady Davis Institute, Jewish General Hospital, Montréal, Québec H3T1E2, Canada; Department of Medicine, Division of Experimental Medicine, McGill University, Montréal, Québec H3A 1A3, Canada.
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27
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Kumar A, Herbein G. The macrophage: a therapeutic target in HIV-1 infection. MOLECULAR AND CELLULAR THERAPIES 2014; 2:10. [PMID: 26056579 PMCID: PMC4452058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Subscribe] [Scholar Register] [Received: 10/27/2013] [Accepted: 01/27/2014] [Indexed: 11/21/2023]
Abstract
Human immunodeficiency virus (HIV) is still a serious global health concern responsible for more than 25 million deaths in last three decades. More than 34 million people are living with HIV infection. Macrophages and CD4+ T cells are the principal targets of HIV-1. The pathogenesis of HIV-1 takes different routes in macrophages and CD4+ T cells. Macrophages are resistant to the cytopathic effect of HIV-1 and produce virus for longer periods of time. In addition, macrophages being present in every organ system thus can disseminate virus to the different anatomical sites leading to the formation of viral sanctuaries. Complete cure of HIV-1 needs better understanding of viral pathogenesis in these reservoirs and implementation of knowledge into robust therapeutic products. In this review we will focus on the unique relationship between HIV-1 and macrophages. Furthermore, we will describe how successful antiretroviral therapy (ART) is in suppressing HIV and novel molecular and cellular strategies against HIV-1 in macrophages.
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Affiliation(s)
- Amit Kumar
- />Department of Virology, UPRES EA4266 Pathogens & Inflammation, University of Franche-Comte, SFR FED 4234, F-25030 Besançon, France
| | - Georges Herbein
- />Department of Virology, UPRES EA4266 Pathogens & Inflammation, University of Franche-Comte, SFR FED 4234, F-25030 Besançon, France
- />Department of Virology, Hôpital Saint-Jacques, CHRU Besançon, 2 place Saint-Jacques, F-25030 Besançon cedex, France
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28
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Kumar A, Herbein G. The macrophage: a therapeutic target in HIV-1 infection. MOLECULAR AND CELLULAR THERAPIES 2014; 2:10. [PMID: 26056579 PMCID: PMC4452058 DOI: 10.1186/2052-8426-2-10] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/27/2013] [Accepted: 01/27/2014] [Indexed: 12/21/2022]
Abstract
Human immunodeficiency virus (HIV) is still a serious global health concern responsible for more than 25 million deaths in last three decades. More than 34 million people are living with HIV infection. Macrophages and CD4+ T cells are the principal targets of HIV-1. The pathogenesis of HIV-1 takes different routes in macrophages and CD4+ T cells. Macrophages are resistant to the cytopathic effect of HIV-1 and produce virus for longer periods of time. In addition, macrophages being present in every organ system thus can disseminate virus to the different anatomical sites leading to the formation of viral sanctuaries. Complete cure of HIV-1 needs better understanding of viral pathogenesis in these reservoirs and implementation of knowledge into robust therapeutic products. In this review we will focus on the unique relationship between HIV-1 and macrophages. Furthermore, we will describe how successful antiretroviral therapy (ART) is in suppressing HIV and novel molecular and cellular strategies against HIV-1 in macrophages.
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Affiliation(s)
- Amit Kumar
- Department of Virology, UPRES EA4266 Pathogens & Inflammation, University of Franche-Comte, SFR FED 4234, F-25030 Besançon, France
| | - Georges Herbein
- Department of Virology, UPRES EA4266 Pathogens & Inflammation, University of Franche-Comte, SFR FED 4234, F-25030 Besançon, France ; Department of Virology, Hôpital Saint-Jacques, CHRU Besançon, 2 place Saint-Jacques, F-25030 Besançon cedex, France
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29
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Guenzel CA, Hérate C, Benichou S. HIV-1 Vpr-a still "enigmatic multitasker". Front Microbiol 2014; 5:127. [PMID: 24744753 PMCID: PMC3978352 DOI: 10.3389/fmicb.2014.00127] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Accepted: 03/12/2014] [Indexed: 11/13/2022] Open
Abstract
Like other HIV-1 auxiliary proteins, Vpr is conserved within all the human (HIV-1, HIV-2) and simian (SIV) immunodeficiency viruses. However, Vpr and homologous HIV-2, and SIV Vpx are the only viral auxiliary proteins specifically incorporated into virus particles through direct interaction with the Gag precursor, indicating that this presence in the core of the mature virions is mainly required for optimal establishment of the early steps of the virus life cycle in the newly infected cell. In spite of its small size, a plethora of effects and functions have been attributed to Vpr, including induction of cell cycle arrest and apoptosis, modulation of the fidelity of reverse transcription, nuclear import of viral DNA in macrophages and other non-dividing cells, and transcriptional modulation of viral and host cell genes. Even if some more recent studies identified a few cellular targets that HIV-1 Vpr may utilize in order to perform its different tasks, the real role and functions of Vpr during the course of natural infection are still enigmatic. In this review, we will summarize the main reported functions of HIV-1 Vpr and their significance in the context of the viral life cycle.
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Affiliation(s)
- Carolin A Guenzel
- Cochin Institute, INSERM U1016, Centre National de la Recherche Scientifique UMR8104, Université Paris-Descartes Paris, France
| | - Cécile Hérate
- Cochin Institute, INSERM U1016, Centre National de la Recherche Scientifique UMR8104, Université Paris-Descartes Paris, France
| | - Serge Benichou
- Cochin Institute, INSERM U1016, Centre National de la Recherche Scientifique UMR8104, Université Paris-Descartes Paris, France
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30
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Viral subversion of the nuclear pore complex. Viruses 2013; 5:2019-42. [PMID: 23959328 PMCID: PMC3761240 DOI: 10.3390/v5082019] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 07/29/2013] [Accepted: 08/08/2013] [Indexed: 12/17/2022] Open
Abstract
The nuclear pore complex (NPC) acts as a selective barrier between the nucleus and the cytoplasm and is responsible for mediating communication by regulating the transport of RNA and proteins. Numerous viral pathogens have evolved different mechanisms to hijack the NPC in order to regulate trafficking of viral proteins, genomes and even capsids into and out of the nucleus thus promoting virus replication. The present review examines the different strategies and the specific nucleoporins utilized during viral infections as a means of promoting their life cycle and inhibiting host viral defenses.
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31
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Barrero CA, Datta PK, Sen S, Deshmane S, Amini S, Khalili K, Merali S. HIV-1 Vpr modulates macrophage metabolic pathways: a SILAC-based quantitative analysis. PLoS One 2013; 8:e68376. [PMID: 23874603 PMCID: PMC3709966 DOI: 10.1371/journal.pone.0068376] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2013] [Accepted: 05/29/2013] [Indexed: 01/09/2023] Open
Abstract
Human immunodeficiency virus type 1 encoded viral protein Vpr is essential for infection of macrophages by HIV-1. Furthermore, these macrophages are resistant to cell death and are viral reservoir. However, the impact of Vpr on the macrophage proteome is yet to be comprehended. The goal of the present study was to use a stable-isotope labeling by amino acids in cell culture (SILAC) coupled with mass spectrometry-based proteomics approach to characterize the Vpr response in macrophages. Cultured human monocytic cells, U937, were differentiated into macrophages and transduced with adenovirus construct harboring the Vpr gene. More than 600 proteins were quantified in SILAC coupled with LC-MS/MS approach, among which 136 were significantly altered upon Vpr overexpression in macrophages. Quantified proteins were selected and clustered by biological functions, pathway and network analysis using Ingenuity computational pathway analysis. The proteomic data illustrating increase in abundance of enzymes in the glycolytic pathway (pentose phosphate and pyruvate metabolism) was further validated by western blot analysis. In addition, the proteomic data demonstrate down regulation of some key mitochondrial enzymes such as glutamate dehydrogenase 2 (GLUD2), adenylate kinase 2 (AK2) and transketolase (TKT). Based on these observations we postulate that HIV-1 hijacks the macrophage glucose metabolism pathway via the Vpr-hypoxia inducible factor 1 alpha (HIF-1 alpha) axis to induce expression of hexokinase (HK), glucose-6-phosphate dehyrogenase (G6PD) and pyruvate kinase muscle type 2 (PKM2) that facilitates viral replication and biogenesis, and long-term survival of macrophages. Furthermore, dysregulation of mitochondrial glutamate metabolism in macrophages can contribute to neurodegeneration via neuroexcitotoxic mechanisms in the context of NeuroAIDS.
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Affiliation(s)
- Carlos A. Barrero
- Department of Biochemistry, Temple University School of Medicine, Fels Institute, Philadelphia, Pennsylvania, United States of America
- Center for Neurovirology, Temple University School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Prasun K. Datta
- Department of Neuroscience, Temple University School of Medicine, Philadelphia, Pennsylvania, United States of America
- Center for Neurovirology, Temple University School of Medicine, Philadelphia, Pennsylvania, United States of America
- * E-mail:
| | - Satarupa Sen
- Department of Neuroscience, Temple University School of Medicine, Philadelphia, Pennsylvania, United States of America
- Department of Biology, Temple University, Philadelphia, Pennsylvania, United States of America
| | - Satish Deshmane
- Department of Neuroscience, Temple University School of Medicine, Philadelphia, Pennsylvania, United States of America
- Center for Neurovirology, Temple University School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Shohreh Amini
- Department of Neuroscience, Temple University School of Medicine, Philadelphia, Pennsylvania, United States of America
- Center for Neurovirology, Temple University School of Medicine, Philadelphia, Pennsylvania, United States of America
- Department of Biology, Temple University, Philadelphia, Pennsylvania, United States of America
| | - Kamel Khalili
- Department of Neuroscience, Temple University School of Medicine, Philadelphia, Pennsylvania, United States of America
- Center for Neurovirology, Temple University School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Salim Merali
- Department of Biochemistry, Temple University School of Medicine, Fels Institute, Philadelphia, Pennsylvania, United States of America
- Center for Neurovirology, Temple University School of Medicine, Philadelphia, Pennsylvania, United States of America
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32
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HIV-1 Vpr activates both canonical and noncanonical NF-κB pathway by enhancing the phosphorylation of IKKα/β. Virology 2013; 439:47-56. [PMID: 23453579 DOI: 10.1016/j.virol.2013.01.020] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Revised: 01/24/2013] [Accepted: 01/25/2013] [Indexed: 11/21/2022]
Abstract
The human immunodeficiency virus type I (HIV-1) Vpr plays an essential role in viral replication. A number of studies have reported that Vpr modulates the nuclear factor-κB (NF-κB) pathway. Yet, the reported effects of Vpr on NF-κB signaling are controversial. In this study, we investigate the interplay between Vpr and NF-κB pathway. We discover that HIV-1 infection elevates the phosphorylation of IκBα and p100, and that this increase is greatly reduced when a Vpr-negative HIV-1 is used for infection. Our data further show that Vpr regulates the activity of IKKα/β through interactions. In addition, Vpr modulates the phosphorylation of p65 and p100, suggesting that Vpr activates both canonical and noncanonical NF-κB pathway. Knock down of endogenous IKKα/β result in a decrease in Vpr-mediated NF-κB and HIV-1 LTR activation. Given that Vpr is present in HIV-1 particles, our data suggest that Vpr activates the NF-κB pathway immediately after HIV-1 entry.
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33
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Lyonnais S, Gorelick RJ, Heniche-Boukhalfa F, Bouaziz S, Parissi V, Mouscadet JF, Restle T, Gatell JM, Le Cam E, Mirambeau G. A protein ballet around the viral genome orchestrated by HIV-1 reverse transcriptase leads to an architectural switch: from nucleocapsid-condensed RNA to Vpr-bridged DNA. Virus Res 2013; 171:287-303. [PMID: 23017337 PMCID: PMC3552025 DOI: 10.1016/j.virusres.2012.09.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2012] [Revised: 09/13/2012] [Accepted: 09/14/2012] [Indexed: 12/15/2022]
Abstract
HIV-1 reverse transcription is achieved in the newly infected cell before viral DNA (vDNA) nuclear import. Reverse transcriptase (RT) has previously been shown to function as a molecular motor, dismantling the nucleocapsid complex that binds the viral genome as soon as plus-strand DNA synthesis initiates. We first propose a detailed model of this dismantling in close relationship with the sequential conversion from RNA to double-stranded (ds) DNA, focusing on the nucleocapsid protein (NCp7). The HIV-1 DNA-containing pre-integration complex (PIC) resulting from completion of reverse transcription is translocated through the nuclear pore. The PIC nucleoprotein architecture is poorly understood but contains at least two HIV-1 proteins initially from the virion core, namely integrase (IN) and the viral protein r (Vpr). We next present a set of electron micrographs supporting that Vpr behaves as a DNA architectural protein, initiating multiple DNA bridges over more than 500 base pairs (bp). These complexes are shown to interact with NCp7 bound to single-stranded nucleic acid regions that are thought to maintain IN binding during dsDNA synthesis, concurrently with nucleocapsid complex dismantling. This unexpected binding of Vpr conveniently leads to a compacted but filamentous folding of the vDNA that should favor its nuclear import. Finally, nucleocapsid-like aggregates engaged in dsDNA synthesis appear to efficiently bind to F-actin filaments, a property that may be involved in targeting complexes to the nuclear envelope. More generally, this article highlights unique possibilities offered by in vitro reconstitution approaches combined with macromolecular imaging to gain insights into the mechanisms that alter the nucleoprotein architecture of the HIV-1 genome, ultimately enabling its insertion into the nuclear chromatin.
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MESH Headings
- DNA Packaging
- DNA, Viral/chemistry
- DNA, Viral/genetics
- DNA, Viral/metabolism
- Genome, Viral
- HIV Integrase/genetics
- HIV Integrase/metabolism
- HIV Reverse Transcriptase/genetics
- HIV Reverse Transcriptase/metabolism
- HIV-1/chemistry
- HIV-1/enzymology
- HIV-1/genetics
- HIV-1/metabolism
- Humans
- RNA, Viral/chemistry
- RNA, Viral/genetics
- RNA, Viral/metabolism
- Reverse Transcription
- gag Gene Products, Human Immunodeficiency Virus/genetics
- gag Gene Products, Human Immunodeficiency Virus/metabolism
- vpr Gene Products, Human Immunodeficiency Virus
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Affiliation(s)
| | - Robert J. Gorelick
- AIDS and Cancer Virus Program; SAIC-Frederick, Inc.; Frederick National Laboratory for Cancer Research; Frederick, MD USA
| | - Fatima Heniche-Boukhalfa
- Maintenance des génomes, Microscopies Moléculaire et Bionanosciences; UMR 8126 CNRS-Université Paris Sud, Villejuif, F-94805, France
| | - Serge Bouaziz
- Laboratoire de Cristallographie et RMN biologiques; UMR 8015 CNRS-Université Paris Descartes; Paris, F-75006, France
| | - Vincent Parissi
- Laboratoire de Microbiologie Fondamentale et Pathogénicité, UMR5234 CNRS-Université Bordeaux Segalen, France
| | | | - Tobias Restle
- Institute of Molecular Medicine, University of Lübeck, Center for Structural and Cell Biology in Medicine (CSCM), D-23538 Lübeck, Germany
| | | | - Eric Le Cam
- Maintenance des génomes, Microscopies Moléculaire et Bionanosciences; UMR 8126 CNRS-Université Paris Sud, Villejuif, F-94805, France
| | - Gilles Mirambeau
- AIDS Research Group; IDIBAPS; E-08036 Barcelona, Spain
- Faculté de Biologie; UPMC Sorbonne Universités; Paris, F-75005, France
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Fujita M, Nomaguchi M, Adachi A, Otsuka M. SAMHD1-Dependent and -Independent Functions of HIV-2/SIV Vpx Protein. Front Microbiol 2012; 3:297. [PMID: 22908011 PMCID: PMC3415948 DOI: 10.3389/fmicb.2012.00297] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2012] [Accepted: 07/25/2012] [Indexed: 12/20/2022] Open
Abstract
Both human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) encode a unique set of accessory proteins that enhance viral replication in the host. Two similar accessory proteins, Vpx and Vpr, are encoded by HIV-2. In contrast, HIV-1 encodes Vpr but not Vpx. Recent studies have indicated that Vpx counteracts a particular host restriction factor, thereby facilitating reverse transcription in myeloid cells such as monocyte-derived macrophages and monocyte-derived dendritic cells. This mechanism of counteraction is similar to that of the accessory proteins Vif and Vpu which antagonize other host factors. In 2011, the protein SAMHD1 was identified as the restriction factor counteracted by Vpx. Studies have since revealed that SAMHD1 degrades deoxynucleoside triphosphates (dNTPs), which are components of viral genomic cDNA, in order to deprive viruses of dNTPs. Although interactions between SAMHD1 and Vpx continue to be a major research focus, Vpx has also been shown to have an apparent ability to enhance nuclear import of the viral genome in T lymphocytes. This review summarizes the current knowledge regarding SAMHD1-dependent and -independent functions of Vpx, and discusses possible reasons why HIV-2 encodes both Vpx and Vpr, unlike HIV-1.
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Affiliation(s)
- Mikako Fujita
- Research Institute for Drug Discovery, School of Pharmacy, Kumamoto University Kumamoto, Japan
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35
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Sörgel S, Fraedrich K, Votteler J, Thomas M, Stamminger T, Schubert U. Perinuclear localization of the HIV-1 regulatory protein Vpr is important for induction of G2-arrest. Virology 2012; 432:444-51. [PMID: 22832123 DOI: 10.1016/j.virol.2012.06.027] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2012] [Revised: 04/07/2012] [Accepted: 06/21/2012] [Indexed: 11/30/2022]
Abstract
The HIV-1 accessory protein Vpr induces G2 cell cycle arrest and apoptosis. Previous studies indicate that the induction of G2-arrest requires the localization of Vpr to the nuclear envelope. Here we show that treatment of Vpr-expressing HeLa cells with the caspase 3 inhibitor Z-DEVD-fmk induced accumulation of Vpr at the nuclear lamina, while other proteins or structures of the nuclear envelope were not influenced. Furthermore, Z-DEVD-fmk enhances the Vpr-mediated G2-arrest that even occurred in HIV-1(NL4-3)-infected T-cells. Mutation of Pro-35, which is important for the integrity of helix-α1 in Vpr, completely abrogated the Z-DEVD-fmk-mediated accumulation of Vpr at the nuclear lamina and the enhancement of G2-arrest. As expected, inhibition of caspase 3 reduced the induction of apoptosis by Vpr. Taken together, we could show that besides its role in Vpr-mediated apoptosis induction caspase 3 influences the localization of Vpr at the nuclear envelope and thereby augments the Vpr-induced G2-arrest.
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Affiliation(s)
- Stefan Sörgel
- Institute of Virology, University of Erlangen-Nuremberg, Erlangen 91054, Germany.
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36
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HIV-1 induces telomerase activity in monocyte-derived macrophages, possibly safeguarding one of its reservoirs. J Virol 2012; 86:10327-37. [PMID: 22787205 DOI: 10.1128/jvi.01495-12] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Monocyte-derived macrophages (MDM) are widely distributed in all tissues and organs, including the central nervous system, where they represent the main part of HIV-infected cells. In contrast to activated CD4(+) T lymphocytes, MDM are resistant to cytopathic effects and survive HIV infection for a long period of time. The molecular mechanisms of how HIV is able to persist in macrophages are not fully elucidated yet. In this context, we have studied the effect of in vitro HIV-1 infection on telomerase activity (TA), telomere length, and DNA damage. Infection resulted in a significant induction of TA. This increase was directly proportional to the efficacy of HIV infection and was found in both nuclear and cytoplasmic extracts, while neither UV light-inactivated HIV nor exogenous addition of the viral protein Tat or gp120 affected TA. Furthermore, TA was not modified during monocyte-macrophage differentiation, MDM activation, or infection with vaccinia virus. HIV infection did not affect telomere length. However, HIV-infected MDM showed less DNA damage after oxidative stress than noninfected MDM, and this resistance was also increased by overexpressing telomerase alone. Taken together, our results suggest that HIV induces TA in MDM and that this induction might contribute to cellular protection against oxidative stress, which could be considered a viral strategy to make macrophages better suited as longer-lived, more resistant viral reservoirs. In the light of the clinical development of telomerase inhibitors as anticancer therapeutics, inhibition of TA in HIV-infected macrophages might also represent a novel therapeutic target against viral reservoirs.
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37
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Jayappa KD, Ao Z, Yao X. The HIV-1 passage from cytoplasm to nucleus: the process involving a complex exchange between the components of HIV-1 and cellular machinery to access nucleus and successful integration. INTERNATIONAL JOURNAL OF BIOCHEMISTRY AND MOLECULAR BIOLOGY 2012; 3:70-85. [PMID: 22509482 PMCID: PMC3325773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Accepted: 02/22/2012] [Indexed: 05/31/2023]
Abstract
The human immunodeficiency virus 1 (HIV-1) synthesizes its genomic DNA in cytoplasm as soon as it enters the cell. The newly synthesized DNA remains associated with viral/cellular proteins as a high molecular weight pre-integration complex (PIC), which precludes passive diffusion across intact nuclear membrane. However, HIV-1 successfully overcomes nuclear membrane barrier by actively delivering its DNA into nucleus with the help of host nuclear import machinery. Such ability allows HIV-1 to productively infect non-dividing cells as well as dividing cells at interphase. Further, HIV-1 nuclear import is also found important for the proper integration of viral DNA. Thus, nuclear import plays a crucial role in establishment of infection and disease progression. While several viral components, including matrix, viral protein R, integrase, capsid, and central DNA flap are implicated in HIV-1 nuclear import, their molecular mechanism remains poorly understood. In this review, we will elaborate the role of individual viral factors and some of current insights on their molecular mechanism(s) associated with HIV-1 nuclear import. In addition, we will discuss the importance of nuclear import for subsequent step of viral DNA integration. Hereby we aim to further our understanding on molecular mechanism of HIV-1 nuclear import and its potential usefulness for anti-HIV-1 strategies.
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Affiliation(s)
- Kallesh Danappa Jayappa
- Laboratory of Molecular Human Retrovirology, Department of Medical Microbiology, Faculty of Medicine, University of Manitoba Winnipeg, MB, Canada
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38
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Wen X, Casey Klockow L, Nekorchuk M, Sharifi HJ, de Noronha CMC. The HIV1 protein Vpr acts to enhance constitutive DCAF1-dependent UNG2 turnover. PLoS One 2012; 7:e30939. [PMID: 22292079 PMCID: PMC3265533 DOI: 10.1371/journal.pone.0030939] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Accepted: 12/26/2011] [Indexed: 02/01/2023] Open
Abstract
Background The HIV1 protein Vpr assembles with and acts through an ubiquitin ligase complex that includes DDB1 and cullin 4 (CRL4) to cause G2 cell cycle arrest and to promote degradation of both uracil DNA glycosylase 2 (UNG2) and single-strand selective mono-functional uracil DNA glycosylase 1 (SMUG1). DCAF1, an adaptor protein, is required for Vpr-mediated G2 arrest through the ubiquitin ligase complex. In work described here, we used UNG2 as a model substrate to study how Vpr acts through the ubiquitin ligase complex. We examined whether DCAF1 is essential for Vpr-mediated degradation of UNG2 and SMUG1. We further investigated whether Vpr is required for recruiting substrates to the ubiquitin ligase or acts to enhance its function and whether this parallels Vpr-mediated G2 arrest. Methodology/Principal Findings We found that DCAF1 plays an important role in Vpr-independent UNG2 and SMUG1 depletion. UNG2 assembled with the ubiquitin ligase complex in the absence of Vpr, but Vpr enhanced this interaction. Further, Vpr-mediated enhancement of UNG2 degradation correlated with low Vpr expression levels. Vpr concentrations exceeding a threshold blocked UNG2 depletion and enhanced its accumulation in the cell nucleus. A similar dose-dependent trend was seen for Vpr-mediated cell cycle arrest. Conclusions/Significance This work identifies UNG2 and SMUG1 as novel targets for CRL4DCAF1-mediated degradation. It further shows that Vpr enhances rather than enables the interaction between UNG2 and the ubiquitin ligase. Vpr augments CRL4DCAF1-mediated UNG2 degradation at low concentrations but antagonizes it at high concentrations, allowing nuclear accumulation of UNG2. Further, the protein that is targeted to cause G2 arrest behaves much like UNG2. Our findings provide the basis for determining whether the CRL4DCAF1 complex is alone responsible for cell cycle-dependent UNG2 turnover and will also aid in establishing conditions necessary for the identification of additional targets of Vpr-enhanced degradation.
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Affiliation(s)
- Xiaoyun Wen
- Center for Immunology and Microbial Disease, Albany Medical College, Albany, New York, United States of America
| | - Laurieann Casey Klockow
- Center for Immunology and Microbial Disease, Albany Medical College, Albany, New York, United States of America
| | - Michael Nekorchuk
- Center for Immunology and Microbial Disease, Albany Medical College, Albany, New York, United States of America
| | - Hamayun J. Sharifi
- Center for Immunology and Microbial Disease, Albany Medical College, Albany, New York, United States of America
| | - Carlos M. C. de Noronha
- Center for Immunology and Microbial Disease, Albany Medical College, Albany, New York, United States of America
- * E-mail:
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Solbak SMØ, Wray V, Horvli O, Raae AJ, Flydal MI, Henklein P, Henklein P, Nimtz M, Schubert U, Fossen T. The host-pathogen interaction of human cyclophilin A and HIV-1 Vpr requires specific N-terminal and novel C-terminal domains. BMC STRUCTURAL BIOLOGY 2011; 11:49. [PMID: 22185200 PMCID: PMC3269379 DOI: 10.1186/1472-6807-11-49] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Accepted: 12/20/2011] [Indexed: 12/26/2022]
Abstract
BACKGROUND Cyclophilin A (CypA) represents a potential key molecule in future antiretroviral therapy since inhibition of CypA suppresses human immunodeficiency virus type 1 (HIV-1) replication. CypA interacts with the virus proteins Capsid (CA) and Vpr, however, the mechanism through which CypA influences HIV-1 infectivity still remains unclear. RESULTS Here the interaction of full-length HIV-1 Vpr with the host cellular factor CypA has been characterized and quantified by surface plasmon resonance spectroscopy. A C-terminal region of Vpr, comprising the 16 residues 75GCRHSRIGVTRQRRAR90, with high binding affinity for CypA has been identified. This region of Vpr does not contain any proline residues but binds much more strongly to CypA than the previously characterized N-terminal binding domain of Vpr, and is thus the first protein binding domain to CypA described involving no proline residues. The fact that the mutant peptide Vpr75-90 R80A binds more weakly to CypA than the wild-type peptide confirms that Arg-80 is a key residue in the C-terminal binding domain. The N- and C-terminal binding regions of full-length Vpr bind cooperatively to CypA and have allowed a model of the complex to be created. The dissociation constant of full-length Vpr to CypA was determined to be approximately 320 nM, indicating that the binding may be stronger than that of the well characterized interaction of HIV-1 CA with CypA. CONCLUSIONS For the first time the interaction of full-length Vpr and CypA has been characterized and quantified. A non-proline-containing 16-residue region of C-terminal Vpr which binds specifically to CypA with similar high affinity as full-length Vpr has been identified. The fact that this is the first non-proline containing binding motif of any protein found to bind to CypA, changes the view on how CypA is able to interact with other proteins. It is interesting to note that several previously reported key functions of HIV-1 Vpr are associated with the identified N- and C-terminal binding domains of the protein to CypA.
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Affiliation(s)
- Sara M Ø Solbak
- Centre of Pharmacy, University of Bergen, N-5007 Bergen Norway
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Fourati S, Malet I, Guenzel CA, Soulie C, Maidou-Peindara P, Morand-Joubert L, Wirden M, Sayon S, Peytavin G, Simon A, Katlama C, Benichou S, Calvez V, Marcelin AG. E17A mutation in HIV-1 Vpr confers resistance to didanosine in association with thymidine analog mutations. Antiviral Res 2011; 93:167-74. [PMID: 22138483 DOI: 10.1016/j.antiviral.2011.11.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Revised: 11/02/2011] [Accepted: 11/16/2011] [Indexed: 11/18/2022]
Abstract
BACKGROUND HIV-1 accessory Vpr protein is involved in the reverse transcription process and has been shown to modulate the virus mutation rate. This process may play a role in the kinetics of appearance of drug resistance mutations under antiretroviral treatment. METHODS Vpr sequences were analyzed from plasma viruses derived from 97 HIV-1-infected individuals failing antiretroviral treatment and 63 antiretroviral-naïve patients. Vpr genetic variability was analyzed for association with specific drug treatment and drug resistance mutations. Biological and virological experiments were employed to characterize a mutation in Vpr found to be associated with virological failure. RESULTS E17A mutation located in the first α-helix of Vpr was more prevalent in HAART-treated individuals compared to untreated individuals. E17A was associated with thymidine analog mutations (TAMs) in reverse transcriptase M41L, L210W and T215Y and with the use of didanosine in the patients' treatment histories. E17A had no impact on the biochemical and functional properties of Vpr, and did not affect kinetics of replication of wild-type or TAMs-containing viruses. However, its association with TAMs and the use of didanosine was consistent with phenotypic susceptibility assays showing a significant 3-fold decrease in didanosine susceptibility of viruses harboring Vpr E17A combined with TAMs compared to viruses harboring TAMs alone. CONCLUSION These findings highlight a novel role of Vpr in HIV-1 drug resistance. Vpr E17A confers resistance to didanosine when associated with TAMs. Whether Vpr E17A facilitates excision of didanosine is still to be determined.
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Affiliation(s)
- Slim Fourati
- Université Pierre et Marie Curie, Paris, France.
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Takeda E, Murakami T, Matsuda G, Murakami H, Zako T, Maeda M, Aida Y. Nuclear exportin receptor CAS regulates the NPI-1-mediated nuclear import of HIV-1 Vpr. PLoS One 2011; 6:e27815. [PMID: 22110766 PMCID: PMC3218035 DOI: 10.1371/journal.pone.0027815] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2011] [Accepted: 10/26/2011] [Indexed: 11/24/2022] Open
Abstract
Vpr, an accessory protein of human immunodeficiency virus type 1, is a multifunctional protein that plays an important role in viral replication. We have previously shown that the region between residues 17 and 74 of Vpr (VprN17C74) contained a bona fide nuclear localization signal and it is targeted VprN17C74 to the nuclear envelope and then imported into the nucleus by importin α (Impα) alone. The interaction between Impα and Vpr is important not only for the nuclear import of Vpr but also for HIV-1 replication in macrophages; however, it was unclear whether full-length Vpr enters the nucleus in a manner similar to VprN17C74. This study investigated the nuclear import of full-length Vpr using the three typical Impα isoforms, Rch1, Qip1 and NPI-1, and revealed that full-length Vpr is selectively imported by NPI-1, but not Rch1 and Qip1, after it makes contact with the perinuclear region in digitonin-permeabilized cells. A binding assay using the three Impα isoforms showed that Vpr bound preferentially to the ninth armadillo repeat (ARM) region (which is also essential for the binding of CAS, the export receptor for Impα) in all three isoforms. Comparison of biochemical binding affinities between Vpr and the Impα isoforms using surface plasmon resonance analysis demonstrated almost identical values for the binding of Vpr to the full-length isoforms and to their C-terminal domains. By contrast, the data showed that, in the presence of CAS, Vpr was released from the Vpr/NPI-1 complex but was not released from Rch1 or Qip1. Finally, the NPI-1–mediated nuclear import of Vpr was greatly reduced in semi-intact CAS knocked-down cells and was recovered by the addition of exogenous CAS. This report is the first to show the requirement for and the regulation of CAS in the functioning of the Vpr-Impα complex.
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Affiliation(s)
- Eri Takeda
- Viral Infectious Diseases Unit, RIKEN, Hirosawa, Wako, Saitama, Japan
| | - Tomoyuki Murakami
- Viral Infectious Diseases Unit, RIKEN, Hirosawa, Wako, Saitama, Japan
- Laboratory of Viral Infectious Diseases, Department of Medical Genome Sciences, Graduate School of Frontier Science, The University of Tokyo, Wako, Saitama, Japan
| | - Go Matsuda
- Viral Infectious Diseases Unit, RIKEN, Hirosawa, Wako, Saitama, Japan
| | - Hironobu Murakami
- Viral Infectious Diseases Unit, RIKEN, Hirosawa, Wako, Saitama, Japan
- Japan Foundation for AIDS Prevention, Chiyoda-ku, Tokyo, Japan
| | - Tamotsu Zako
- Bioengineering Laboratory, RIKEN, Hirosawa, Wako, Saitama, Japan
| | - Mizuo Maeda
- Bioengineering Laboratory, RIKEN, Hirosawa, Wako, Saitama, Japan
| | - Yoko Aida
- Viral Infectious Diseases Unit, RIKEN, Hirosawa, Wako, Saitama, Japan
- Laboratory of Viral Infectious Diseases, Department of Medical Genome Sciences, Graduate School of Frontier Science, The University of Tokyo, Wako, Saitama, Japan
- * E-mail:
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Mukerjee R, Chang JR, Del Valle L, Bagashev A, Gayed MM, Lyde RB, Hawkins BJ, Brailoiu E, Cohen E, Power C, Azizi SA, Gelman BB, Sawaya BE. Deregulation of microRNAs by HIV-1 Vpr protein leads to the development of neurocognitive disorders. J Biol Chem 2011; 286:34976-85. [PMID: 21816823 PMCID: PMC3186354 DOI: 10.1074/jbc.m111.241547] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Revised: 08/02/2011] [Indexed: 12/23/2022] Open
Abstract
Studies have shown that HIV-infected patients develop neurocognitive disorders characterized by neuronal dysfunction. The lack of productive infection of neurons by HIV suggests that viral and cellular proteins, with neurotoxic activities, released from HIV-1-infected target cells can cause this neuronal deregulation. The viral protein R (Vpr), a protein encoded by HIV-1, has been shown to alter the expression of various important cytokines and inflammatory proteins in infected and uninfected cells; however the mechanisms involved remain unclear. Using a human neuronal cell line, we found that Vpr can be taken up by neurons causing: (i) deregulation of calcium homeostasis, (ii) endoplasmic reticulum-calcium release, (iii) activation of the oxidative stress pathway, (iv) mitochondrial dysfunction and v- synaptic retraction. In search for the cellular factors involved, we performed microRNAs and gene array assays using human neurons (primary cultures or cell line, SH-SY5Y) that we treated with recombinant Vpr proteins. Interestingly, Vpr deregulates the levels of several microRNAs (e.g. miR-34a) and their target genes (e.g. CREB), which could lead to neuronal dysfunctions. Therefore, we conclude that Vpr plays a major role in neuronal dysfunction through deregulating microRNAs and their target genes, a phenomenon that could lead to the development of neurocognitive disorders.
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Affiliation(s)
| | | | - Luis Del Valle
- the Department of Medicine, Section of Hematology/Oncology, and Department of Pathology, Stanley S. Scott Cancer Center, Louisiana State University School of Medicine, New Orleans, Louisiana 70112
| | | | | | | | - Brian J. Hawkins
- Anesthesiology and Pain Medicine, Mitochondria and Metabolism Center, University of Washington, Seattle, Washington 98109
| | - Eugen Brailoiu
- Pharmacology, Molecular Studies of Neurodegenerative Diseases Laboratory, Temple University School of Medicine, Philadelphia, Pennsylvania 19140
| | - Eric Cohen
- the Institut de Recherches Cliniques de Montréal (IRCM) and Department of Microbiology and Immunology, Université de Montréal, Quebec, Canada
| | - Chris Power
- the Departments of Medicine (Neurology), Medical Microbiology & Immunology, and Psychiatry, University of Alberta, Edmonton, Alberta T6G 2S2, Canada, and
| | | | - Benjamin B. Gelman
- the Departments of Pathology and Neuroscience & Cell Biology, Texas NeuroAIDS Research Center, University of Texas Medical Branch, Galveston, Texas 77555-0609
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Greiner VJ, Shvadchak V, Fritz J, Arntz Y, Didier P, Frisch B, Boudier C, Mély Y, de Rocquigny H. Characterization of the mechanisms of HIV-1 Vpr(52–96) internalization in cells. Biochimie 2011; 93:1647-58. [DOI: 10.1016/j.biochi.2011.05.033] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Accepted: 05/31/2011] [Indexed: 02/08/2023]
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44
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Cellular phenotype impacts human immunodeficiency virus type 1 viral protein R subcellular localization. Virol J 2011; 8:397. [PMID: 21831263 PMCID: PMC3168423 DOI: 10.1186/1743-422x-8-397] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Accepted: 08/10/2011] [Indexed: 01/01/2023] Open
Abstract
Background Human immunodeficiency virus type 1 (HIV-1) viral protein R (Vpr) is a virion-associated regulatory protein that functions at several points within the viral life cycle and has been shown to accumulate primarily in the nucleus and at the nuclear envelope. However, most studies have investigated Vpr localization employing cell types irrelevant to HIV-1 pathogenesis. To gain a better understanding of how cellular phenotype might impact HIV-1 Vpr intracellular localization, Vpr localization was examined in several cell lines representing major cellular targets for HIV-1 infection within the peripheral blood, bone marrow, and central nervous system (CNS). Results Utilizing a green fluorescent protein-tagged Vpr, we detected Vpr mainly in foci inside the nucleus, at the nuclear envelope, and around the nucleoli, with dispersed accumulation in the cytoplasm of human endothelial kidney 293T cells. No differences were observed in Vpr localization pattern with respect to either the location of the tag (N- or C-terminus) or the presence of other viral proteins. Subsequently, the Vpr localization pattern was explored in two primary HIV-1 target cells within the peripheral blood: the CD4+ T lymphocyte (represented by the Jurkat CD4+ T-cell line) and the monocyte-macrophage (represented by the U-937 cell line). Vpr was found primarily in speckles within the cytoplasm of the Jurkat T cells, whereas it accumulated predominantly intranuclearly in U-937 monocytic cells. These patterns differ from that observed in a bone marrow progenitor cell line (TF-1), wherein Vpr localized mainly at the nuclear envelope with some intranuclear punctuate staining. Within the CNS, we examined two astroglioma cell lines and found that Vpr displayed a perinuclear and cytoplasmic distribution. Conclusions The results suggest that the pattern of Vpr localization depends on cellular phenotype, probably owing to interactions between Vpr and cell type-specific host factors. These interactions, in turn, are likely coupled to specific roles that Vpr plays in each cell type within the context of the viral life cycle. Phenotype-specific Vpr localization patterns might also provide an explanation with respect to Vpr secretion or release from HIV-1-infected cells within the peripheral blood and CNS.
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Maudet C, Bertrand M, Le Rouzic E, Lahouassa H, Ayinde D, Nisole S, Goujon C, Cimarelli A, Margottin-Goguet F, Transy C. Molecular insight into how HIV-1 Vpr protein impairs cell growth through two genetically distinct pathways. J Biol Chem 2011; 286:23742-52. [PMID: 21566118 DOI: 10.1074/jbc.m111.220780] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Vpr, a small HIV auxiliary protein, hijacks the CUL4 ubiquitin ligase through DCAF1 to inactivate an unknown cellular target, leading to cell cycle arrest at the G(2) phase and cell death. Here we first sought to delineate the Vpr determinants involved in the binding to DCAF1 and to the target. On the one hand, the three α-helices of Vpr are necessary and sufficient for binding to DCAF1; on the other hand, nonlinear determinants in Vpr are required for binding to the target, as shown by using protein chimeras. We also underscore that a SRIG motif conserved in the C-terminal tail of Vpr proteins from HIV-1/SIVcpz and HIV-2/SIVsmm lineages is critical for G(2) arrest. Our results suggest that this motif may be predictive of the ability of Vpr proteins from other SIV lineages to mediate G(2) arrest. We took advantage of the characterization of a subset of G(2) arrest-defective, but DCAF1 binding-proficient mutants, to investigate whether Vpr interferes with cell viability independently of its ability to induce G(2) arrest. These mutants inhibited cell colony formation in HeLa cells and are cytotoxic in lymphocytes, unmasking a G(2) arrest-independent cytopathic effect of Vpr. Furthermore these mutants do not block cell cycle progression at the G(1) or S phases but trigger apoptosis through caspase 3. Disruption of DCAF1 binding restored efficiency of colony formation. However, DCAF1 binding per se is not sufficient to confer cytopathicity. These data support a model in which Vpr recruits DCAF1 to induce the degradation of two host proteins independently required for proper cell growth.
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Ong EBB, Watanabe N, Saito A, Futamura Y, Abd El Galil KH, Koito A, Najimudin N, Osada H. Vipirinin, a coumarin-based HIV-1 Vpr inhibitor, interacts with a hydrophobic region of VPR. J Biol Chem 2011; 286:14049-56. [PMID: 21357691 PMCID: PMC3077605 DOI: 10.1074/jbc.m110.185397] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2010] [Revised: 02/27/2011] [Indexed: 11/06/2022] Open
Abstract
The human immunodeficiency virus 1 (HIV-1) viral protein R (Vpr) is an accessory protein that has been shown to have multiple roles in HIV-1 pathogenesis. By screening chemical libraries in the RIKEN Natural Products Depository, we identified a 3-phenyl coumarin-based compound that inhibited the cell cycle arrest activity of Vpr in yeast and Vpr-dependent viral infection of human macrophages. We determined its minimal pharmacophore through a structure-activity relationship study and produced more potent derivatives. We detected direct binding, and by assaying a panel of Vpr mutants, we found the hydrophobic region about residues Glu-25 and Gln-65 to be potentially involved in the binding of the inhibitor. Our findings exposed a targeting site on Vpr and delineated a convenient approach to explore other targeting sites on the protein using small molecule inhibitors as bioprobes.
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Affiliation(s)
- Eugene Boon Beng Ong
- From the Chemical Biology Core Facility, Chemical Biology Department, RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
- the School of Biological Sciences, Universiti Sains Malaysia, 11800 Penang, Malaysia, and
| | - Nobumoto Watanabe
- From the Chemical Biology Core Facility, Chemical Biology Department, RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
- the School of Biological Sciences, Universiti Sains Malaysia, 11800 Penang, Malaysia, and
| | - Akiko Saito
- From the Chemical Biology Core Facility, Chemical Biology Department, RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
| | - Yushi Futamura
- From the Chemical Biology Core Facility, Chemical Biology Department, RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
| | - Khaled Hussein Abd El Galil
- the Department of Retrovirology and Self-Defense, Faculty of Life Sciences, Kumamoto University, Kumamoto 860-8556, Japan
| | - Atsushi Koito
- the Department of Retrovirology and Self-Defense, Faculty of Life Sciences, Kumamoto University, Kumamoto 860-8556, Japan
| | - Nazalan Najimudin
- the School of Biological Sciences, Universiti Sains Malaysia, 11800 Penang, Malaysia, and
| | - Hiroyuki Osada
- From the Chemical Biology Core Facility, Chemical Biology Department, RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
- the School of Biological Sciences, Universiti Sains Malaysia, 11800 Penang, Malaysia, and
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Kogan M, Rappaport J. HIV-1 accessory protein Vpr: relevance in the pathogenesis of HIV and potential for therapeutic intervention. Retrovirology 2011; 8:25. [PMID: 21489275 PMCID: PMC3090340 DOI: 10.1186/1742-4690-8-25] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2010] [Accepted: 04/13/2011] [Indexed: 01/11/2023] Open
Abstract
The HIV protein, Vpr, is a multifunctional accessory protein critical for efficient viral infection of target CD4+ T cells and macrophages. Vpr is incorporated into virions and functions to transport the preintegration complex into the nucleus where the process of viral integration into the host genome is completed. This action is particularly important in macrophages, which as a result of their terminal differentiation and non-proliferative status, would be otherwise more refractory to HIV infection. Vpr has several other critical functions including activation of HIV-1 LTR transcription, cell-cycle arrest due to DCAF-1 binding, and both direct and indirect contributions to T-cell dysfunction. The interactions of Vpr with molecular pathways in the context of macrophages, on the other hand, support accumulation of a persistent reservoir of HIV infection in cells of the myeloid lineage. The role of Vpr in the virus life cycle, as well as its effects on immune cells, appears to play an important role in the immune pathogenesis of AIDS and the development of HIV induced end-organ disease. In view of the pivotal functions of Vpr in virus infection, replication, and persistence of infection, this protein represents an attractive target for therapeutic intervention.
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Affiliation(s)
- Michael Kogan
- Department of Neuroscience, Department of Neuroscience, Center for Neurovirology, Temple University School of Medicine, 3500 North Broad Street, Philadelphia, PA 19140, USA
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Belzile JP, Abrahamyan LG, Gérard FCA, Rougeau N, Cohen ÉA. Formation of mobile chromatin-associated nuclear foci containing HIV-1 Vpr and VPRBP is critical for the induction of G2 cell cycle arrest. PLoS Pathog 2010; 6:e1001080. [PMID: 20824083 PMCID: PMC2932712 DOI: 10.1371/journal.ppat.1001080] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2010] [Accepted: 07/28/2010] [Indexed: 02/06/2023] Open
Abstract
HIV-1 Viral protein R (Vpr) induces a cell cycle arrest at the G2/M phase by activating the ATR DNA damage/stress checkpoint. Recently, we and several other groups showed that Vpr performs this activity by recruiting the DDB1-CUL4A (VPRBP) E3 ubiquitin ligase. While recruitment of this E3 ubiquitin ligase complex has been shown to be required for G2 arrest, the subcellular compartment where this complex forms and functionally acts is unknown. Herein, using immunofluorescence and confocal microscopy, we show that Vpr forms nuclear foci in several cell types including HeLa cells and primary CD4+ T-lymphocytes. These nuclear foci contain VPRBP and partially overlap with DNA repair foci components such as γ-H2AX, 53BP1 and RPA32. While treatment with the non-specific ATR inhibitor caffeine or depletion of VPRBP by siRNA did not inhibit formation of Vpr nuclear foci, mutations in the C-terminal domain of Vpr and cytoplasmic sequestration of Vpr by overexpression of Gag-Pol resulted in impaired formation of these nuclear structures and defective G2 arrest. Consistently, we observed that G2 arrest-competent sooty mangabey Vpr could form these foci but not its G2 arrest-defective paralog Vpx, suggesting that formation of Vpr nuclear foci represents a critical early event in the induction of G2 arrest. Indeed, we found that Vpr could associate to chromatin via its C-terminal domain and that it could form a complex with VPRBP on chromatin. Finally, analysis of Vpr nuclear foci by time-lapse microscopy showed that they were highly mobile and stable structures. Overall, our results suggest that Vpr recruits the DDB1-CUL4A (VPRBP) E3 ligase to these nuclear foci and uses these mobile structures to target a chromatin-bound cellular substrate for ubiquitination in order to induce DNA damage/replication stress, ultimately leading to ATR activation and G2 cell cycle arrest. HIV-1, the causative agent of AIDS, encodes several proteins termed accessory, which play a critical role in viral pathogenesis. One of these accessory proteins, viral protein R (Vpr), has been found to block normal cell division. This impairment of cell division by Vpr is thought to increase viral replication and to trigger immune cell death. However, how Vpr is able to block cell growth remains unknown. We and other investigators recently showed that Vpr was performing this activity by interacting with a cellular protein complex involved in ubiquitination. Ubiquitination is characterized by the conjugation of a small protein called ubiquitin to various other proteins to regulate their degradation or activities. In this report, we demonstrate that Vpr forms mobile punctuate structures called foci on the DNA of host cells. We also show that formation of these foci by Vpr is required to block cell division. We propose that Vpr recruits the ubiquitination complex to these nuclear foci and uses these mobile structures to target a DNA-bound cellular protein for degradation, resulting in the activation of a host cell response leading to a cell division block. Identification of the unknown cellular factor targeted by Vpr will contribute to the understanding of the role of Vpr during HIV infection and AIDS pathogenesis.
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Affiliation(s)
- Jean-Philippe Belzile
- Laboratory of Human Retrovirology, Institut de Recherches Cliniques de Montréal (IRCM), Montreal, Quebec, Canada
| | - Levon G. Abrahamyan
- Laboratory of Human Retrovirology, Institut de Recherches Cliniques de Montréal (IRCM), Montreal, Quebec, Canada
| | - Francine C. A. Gérard
- Laboratory of Human Retrovirology, Institut de Recherches Cliniques de Montréal (IRCM), Montreal, Quebec, Canada
| | - Nicole Rougeau
- Laboratory of Human Retrovirology, Institut de Recherches Cliniques de Montréal (IRCM), Montreal, Quebec, Canada
| | - Éric A. Cohen
- Laboratory of Human Retrovirology, Institut de Recherches Cliniques de Montréal (IRCM), Montreal, Quebec, Canada
- Department of Microbiology and Immunology, Université de Montréal, Montreal, Quebec, Canada
- * E-mail:
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Fritz JV, Briant L, Mély Y, Bouaziz S, de Rocquigny H. HIV-1 viral protein r: from structure to function. Future Virol 2010. [DOI: 10.2217/fvl.10.47] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The viral protein r (Vpr) of HIV-1 binds several host proteins leading to pleiotropic functions, such as G2/M cell cycle arrest, apoptosis induction and gene transactivation. Vpr is encapsidated through the Gag C-terminus into the nascent viral particles, suggesting that Vpr plays several important functions in the early stages of the viral lifecycle. In this regard, Vpr interacts with nucleic acids and membranes to facilitate the preintegration complex migration and incorporation into the nucleus of nondividing cells. Thus, Vpr has to recruit several host and viral factors to promote its functions during HIV-1 pathogenesis. This article focuses on its interacting partners by giving an overview of the functional outcome of the different Vpr complexes, as well as the structural determinants of Vpr required for its binding properties.
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Affiliation(s)
- Joëlle V Fritz
- Department of Infectious Diseases, Virology, Universitätsklinikum, Im Neuenheimer Feld, 324, D-69120, Heidelberg, Germany
| | - Laurence Briant
- Université Montpellier 1, Centre d’études d’agents Pathogènes et Biotechnologies pour la Santé, CNRS, UMR 5236, CPBS, F-34965 Montpellier, France
| | - Yves Mély
- Laboratoire de Biophotonique et Pharmacologie, UMR 7213 CNRS, Université de Strasbourg, Faculté de Pharmacie, 74, Route du Rhin, 67401 ILLKIRCH Cedex, France
| | - Serge Bouaziz
- Laboratoire de Cristallographie et RMN Biologiques, CNRS UMR8015 UFR des Sciences Pharmaceutiques et Biologiques 4, Avenue de L’observatoire, 75006 Paris, France: Université de Strasbourg, Faculté de Pharmacie, 74, Route du Rhin, 67401 ILLKIRCH Cedex, France
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Romani B, Glashoff RH, Engelbrecht S. Functional integrity of naturally occurring mutants of HIV-1 subtype C Vpr. Virus Res 2010; 153:288-98. [PMID: 20801175 DOI: 10.1016/j.virusres.2010.08.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2010] [Revised: 08/02/2010] [Accepted: 08/19/2010] [Indexed: 02/01/2023]
Abstract
HIV-1 Vpr, an accessory protein with multiple functions, is involved in the induction of apoptosis, cell cycle G2 arrest, and modulation of gene expression. Many functions of this protein have been documented for the wild-type subtype B Vpr, however the functionality of other subtypes has not sufficiently been addressed. In this study, the functionality of Subtype B Vpr, 6 subtype C mutant Vpr proteins and the consensus sequence of subtype C Vpr were compared with each other. All the subtype B and C Vpr proteins localized to the nucleus of human 293T cells. Subtype C Vpr proteins induced cell cycle G2 arrest in a lower proportion of human 293T cells compared to subtype B Vpr. Subtype B and the naturally mutant Vpr proteins induced apoptosis in a similar manner, ranging from 95.33% to 98.64%. However, an artificially designed Vpr protein containing the consensus sequences of subtype C Vpr indicated a reduced ability in induction of apoptosis. The study of mRNA profile of the transfected cells indicated that all Vpr proteins modulated the apoptotic genes triggering the intrinsic pathway of apoptosis. Our results indicate that subtype C Vpr is able to exert the same functions previously reported for subtype B Vpr. Most natural mutations in Vpr not only do not disturb the functions of the protein but also potentiate the protein for an increased functionality. The natural mutations of Vpr may thus not always be regarded as defective mutations. The study suggests the adaptive role of the natural mutations commonly found in subtype C Vpr.
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Affiliation(s)
- Bizhan Romani
- Division of Medical Virology, Department of Pathology, University of Stellenbosch, Tygerberg 7505, South Africa.
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