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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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2
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Multifactorial role of HIV-Vpr in cell apoptosis revealed by a naturally truncated 54aa variant. Chin Med J (Engl) 2020; 134:845-847. [PMID: 33323824 PMCID: PMC8104139 DOI: 10.1097/cm9.0000000000001297] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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3
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Baeyens A, Naessens E, Van Nuffel A, Weening KE, Reilly AM, Claeys E, Trypsteen W, Vandekerckhove L, Eyckerman S, Gevaert K, Verhasselt B. HIV-1 Vpr N-terminal tagging affects alternative splicing of the viral genome. Sci Rep 2016; 6:34573. [PMID: 27721439 PMCID: PMC5056386 DOI: 10.1038/srep34573] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Accepted: 09/12/2016] [Indexed: 01/11/2023] Open
Abstract
To facilitate studies on Vpr function in replicating HIV-1, we aimed to tag the protein in an infectious virus. First we showed that N-, but not C-terminal HA/FLAG tagging of Vpr protein preserves Vpr cytopathicity. Cloning the tags into proviral DNA however ablated viral production and replication. By construction of additional viral variants we could show this defect was not protein- but RNA-dependent and sequence specific, and characterized by oversplicing of the genomic RNA. Simulation of genomic RNA folding suggested that introduction of the tag sequence induced an alternative folding structure in a region enriched in splice sites and splicing regulatory sequences. In silico predictions identified the HA/His6-Vpr tagging in HIV-1 to affect mRNA folding less than HA/FLAG-Vpr tagging. In vitro infectivity and mRNA splice pattern improved but did not reach wild-type values. Thus, sequence-specific insertions may interfere with mRNA splicing, possibly due to altered RNA folding. Our results point to the complexity of viral RNA genome sequence interactions. This should be taken into consideration when designing viral manipulation strategies, for both research as for biological interventions.
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Affiliation(s)
- Ann Baeyens
- Department of Clinical Chemistry, Microbiology, and Immunology, Ghent University, Ghent, Belgium
| | - Evelien Naessens
- Department of Clinical Chemistry, Microbiology, and Immunology, Ghent University, Ghent, Belgium
| | - Anouk Van Nuffel
- Department of Clinical Chemistry, Microbiology, and Immunology, Ghent University, Ghent, Belgium
| | - Karin E Weening
- Department of Clinical Chemistry, Microbiology, and Immunology, Ghent University, Ghent, Belgium
| | - Anne-Marie Reilly
- Department of Clinical Chemistry, Microbiology, and Immunology, Ghent University, Ghent, Belgium
| | - Eva Claeys
- Department of Clinical Chemistry, Microbiology, and Immunology, Ghent University, Ghent, Belgium
| | - Wim Trypsteen
- HIV Translational Research Unit, Department of Internal Medicine, Faculty of Medicine and Health Sciences, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Linos Vandekerckhove
- HIV Translational Research Unit, Department of Internal Medicine, Faculty of Medicine and Health Sciences, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Sven Eyckerman
- VIB Medical Biotechnology Center, B-9000 Ghent, Belgium.,Department of Biochemistry, Ghent University, B-9000 Ghent, Belgium
| | - Kris Gevaert
- VIB Medical Biotechnology Center, B-9000 Ghent, Belgium.,Department of Biochemistry, Ghent University, B-9000 Ghent, Belgium
| | - Bruno Verhasselt
- Department of Clinical Chemistry, Microbiology, and Immunology, Ghent University, Ghent, Belgium
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Abstract
UNLABELLED HIV-1 modulates key host cellular pathways for successful replication and pathogenesis through viral proteins. By evaluating the hijacking of the host ubiquitination pathway by HIV-1 at the whole-cell level, we now show major perturbations in the ubiquitinated pool of the host proteins post-HIV-1 infection. Our overexpression- and infection-based studies of T cells with wild-type and mutant HIV-1 proviral constructs showed that Vpr is necessary and sufficient for reducing whole-cell ubiquitination. Mutagenic analysis revealed that the three leucine-rich helical regions of Vpr are critical for this novel function of Vpr, which was independent of its other known cellular functions. We also validated that this effect of Vpr was conserved among different subtypes (subtypes B and C) and circulating recombinants from Northern India. Finally, we establish that this phenomenon is involved in HIV-1-mediated diversion of host ubiquitination machinery specifically toward the degradation of various restriction factors during viral pathogenesis. IMPORTANCE HIV-1 is known to rely heavily on modulation of the host ubiquitin pathway, particularly for counteraction of antiretroviral restriction factors, i.e., APOBEC3G, UNG2, and BST-2, etc.; viral assembly; and release. Reports to date have focused on the molecular hijacking of the ubiquitin machinery by HIV-1 at the level of E3 ligases. Interaction of a viral protein with an E3 ligase alters its specificity to bring about selective protein ubiquitination. However, in the case of infection, multiple viral proteins can interact with this multienzyme pathway at various levels, making it much more complicated. Here, we have addressed the manipulation of ubiquitination at the whole-cell level post-HIV-1 infection. Our results show that HIV-1 Vpr is necessary and sufficient to bring about the redirection of the host ubiquitin pathway toward HIV-1-specific outcomes. We also show that the three leucine-rich helical regions of Vpr are critical for this effect and that this ability of Vpr is conserved across circulating recombinants. Our work, the first of its kind, provides novel insight into the regulation of the ubiquitin system at the whole-cell level by HIV-1.
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Zych C, Domling A, Ayyavoo V. Development of a robust cell-based high-throughput screening assay to identify targets of HIV-1 viral protein R dimerization. Drug Des Devel Ther 2013; 7:403-12. [PMID: 23737660 PMCID: PMC3668091 DOI: 10.2147/dddt.s44139] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Targeting protein-protein interactions (PPI) is an emerging field in drug discovery. Dimerization and PPI are essential properties of human immunodeficiency virus (HIV)-1 proteins, their mediated functions, and virus biology. Additionally, dimerization is required for the functional interaction of HIV-1 proteins with many host cellular components. In this study, a bimolecular fluorescence complementation (BiFC)-based screening assay was developed that can quantify changes in dimerization, using HIV-1 viral protein R (Vpr) dimerization as a "proof of concept." Results demonstrated that Venus Vpr (generated by BiFC Vpr constructs) could be competed off in a dose-dependent manner using untagged, full-length Vpr as a competitor molecule. The change in signal intensity was measured quantitatively through flow cytometry and fluorescence microscopy in a high content screening assay. High content imaging was used to screen a library of small molecules for an effect on Vpr dimerization. Among the tested molecules, a few of the small molecules demonstrate an effect on Vpr dimerization in a dose-dependent manner.
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Affiliation(s)
- Courtney Zych
- Department of Infectious Diseases and Microbiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA 15261, USA
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Zhang M, Mao X, Wang C, Zeng W, Zhang C, Li Z, Fang Y, Yang Y, Liang W, Wang C. The effect of graphene oxide on conformation change, aggregation and cytotoxicity of HIV-1 regulatory protein (Vpr). Biomaterials 2013; 34:1383-90. [DOI: 10.1016/j.biomaterials.2012.10.067] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2012] [Accepted: 10/28/2012] [Indexed: 10/27/2022]
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7
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Neogi U, Sood V, Ronsard L, Singh J, Lata S, Ramachandran VG, Das S, Wanchu A, Banerjea AC. Genetic architecture of HIV-1 genes circulating in north India & their functional implications. Indian J Med Res 2012; 134:769-78. [PMID: 22310812 PMCID: PMC3284088 DOI: 10.4103/0971-5916.92624] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
This review presents data on genetic and functional analysis of some of the HIV-1 genes derived from HIV-1 infected individuals from north India (Delhi, Punjab and Chandigarh). We found evidence of novel B/C recombinants in HIV-1 LTR region showing relatedness to China/Myanmar with 3 copies of Nfκb sites; B/C/D mosaic genomes for HIV-1 Vpr and novel B/C Tat. We reported appearance of a complex recombinant form CRF_02AG of HIV-1 envelope sequences which is predominantly found in Central/Western Africa. Also one Indian HIV-1 envelope subtype C sequence suggested exclusive CXCR4 co-receptor usage. This extensive recombination, which is observed in about 10 per cent HIV-1 infected individuals in the Vpr genes, resulted in remarkably altered functions when compared with prototype subtype B Vpr. The Vpu C was found to be more potent in causing apoptosis when compared with Vpu B when analyzed for subG1 DNA content. The functional implications of these changes as well as in other genes of HIV-1 are discussed in detail with possible implications for subtype-specific pathogenesis highlighted.
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Affiliation(s)
- Ujjwal Neogi
- Department of Virology, National Institute of Immunology, New Delhi, India
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8
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Barnitz RA, Chaigne-Delalande B, Bolton DL, Lenardo MJ. Exposed hydrophobic residues in human immunodeficiency virus type 1 Vpr helix-1 are important for cell cycle arrest and cell death. PLoS One 2011; 6:e24924. [PMID: 21949789 PMCID: PMC3174981 DOI: 10.1371/journal.pone.0024924] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Accepted: 08/24/2011] [Indexed: 12/28/2022] Open
Abstract
The human immunodeficiency virus type 1 (HIV-1) accessory protein viral protein R (Vpr) is a major determinant for virus-induced G2/M cell cycle arrest and cytopathicity. Vpr is thought to perform these functions through the interaction with partner proteins. The NMR structure of Vpr revealed solvent exposed hydrophobic amino acids along helices 1 and 3 of Vpr, which could be putative protein binding domains. We previously showed that the hydrophobic patch along helix-3 was important for G2/M blockade and cytopathicity. Mutations of the exposed hydrophobic residues along helix-1 were found to reduce Vpr-induced cell cycle arrest and cell death as well. The levels of toxicity during virion delivery of Vpr correlated with G2/M arrest. Thus, the exposed hydrophobic amino acids in the amino-terminal helix-1 are important for the cell cycle arrest and cytopathicity functions of Vpr.
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Affiliation(s)
- R. Anthony Barnitz
- Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
- Immunology Graduate Group, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Benjamin Chaigne-Delalande
- Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Diane L. Bolton
- Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Michael J. Lenardo
- Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
- Immunology Graduate Group, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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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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10
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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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11
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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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Venkatachari NJ, Walker LA, Tastan O, Le T, Dempsey TM, Li Y, Yanamala N, Srinivasan A, Klein-Seetharaman J, Montelaro RC, Ayyavoo V. Human immunodeficiency virus type 1 Vpr: oligomerization is an essential feature for its incorporation into virus particles. Virol J 2010; 7:119. [PMID: 20529298 PMCID: PMC2894018 DOI: 10.1186/1743-422x-7-119] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2010] [Accepted: 06/07/2010] [Indexed: 01/05/2023] Open
Abstract
HIV-1 Vpr, a nonstructural viral protein associated with virus particles, has a positive role in the efficient transport of PIC into the nucleus of non-dividing target cells and enhances virus replication in primary T cells. Vpr is a 96 amino acid protein and the structure by NMR shows three helical domains. Vpr has been shown to exist as dimers and higher order oligomers. Considering the multifunctional nature of Vpr, the contribution of distinct helical domains to the dimer/oligomer structure of Vpr and the relevance of this feature to its functions are not clear. To address this, we have utilized molecular modeling approaches to identify putative models of oligomerization. The predicted interface residues were subjected to site-directed mutagenesis and evaluated their role in intermolecular interaction and virion incorporation. The interaction between Vpr molecules was monitored by Bimolecular Fluorescence complementation (BiFC) method. The results show that Vpr forms oligomers in live cells and residues in helical domains play critical roles in oligomerization. Interestingly, Vpr molecules defective in oligomerization also fail to incorporate into the virus particles. Based on the data, we suggest that oligomerization of Vpr is essential for virion incorporation property and may also have a role in the events associated with virus infection.
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Affiliation(s)
- Narasimhan J Venkatachari
- Department of Infectious Diseases and Microbiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
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13
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Hapgood JP, Tomasicchio M. Modulation of HIV-1 virulence via the host glucocorticoid receptor: towards further understanding the molecular mechanisms of HIV-1 pathogenesis. Arch Virol 2010; 155:1009-19. [PMID: 20446002 DOI: 10.1007/s00705-010-0678-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2009] [Accepted: 03/26/2010] [Indexed: 10/19/2022]
Abstract
The glucocorticoid receptor (GR) is a steroid receptor that regulates diverse functions, which include the immune response. In humans, the GR acts via binding to cortisol, resulting in the transcriptional modulation of key host genes. Several lines of evidence suggest that the host GR could be a key protein exploited by HIV at multiple levels to ensure its pathogenic success. Endogenous and therapeutic glucocorticoids play important roles in patients with HIV due to their well-established effects on immune function. AIDS patients develop glucocorticoid hypersensitivity, consistent with a mechanism involving an HIV-1-induced increase in expression or activity of the GR. Both the HIV-1 accessory protein Vpr and the host GR affect transcription of viral proteins from the long terminal repeat (LTR) region of the HIV-1 promoter. In addition, Vpr modulates host GR function to affect transcription of host genes, most likely via direct interaction with the GR. Vpr appears to regulate GR function by acting as a co-activator for the GR. Since both the GR and Vpr are involved in apoptosis in T cells and dendritic cells, crosstalk between these proteins may also regulate apoptosis in these and other cells. Given that cortisol is not the only ligand that activates the GR, other endogenous as well as synthetic GR ligands such as progestins may also modulate HIV pathogenesis, in particular in the cervicovaginal environment. Investigating the molecular determinants, ligand-selectivity and role in HIV pathogenesis of the GR-Vpr interaction may lead to new strategies for development of anti-HIV drugs.
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Affiliation(s)
- Janet Patricia Hapgood
- Department of Molecular and Cell Biology, University of Cape Town, Rondebosch 7701, South Africa.
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Genetic and functional characterization of human immunodeficiency virus type 1 VprC variants from north India: presence of unique recombinants with mosaic genomes from B, C and D subtypes within the open reading frame of Vpr. J Gen Virol 2009; 90:2768-2776. [DOI: 10.1099/vir.0.011080-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The human immunodeficiency virus type 1 (HIV-1) epidemic in India is predominantly caused by genetic subtype C, though other minor subtypes have also been reported. One of the major accessory proteins of HIV-1, namely Vpr, is known to influence key steps in viral replication, cell cycle progression, promoter activation, apoptosis and pathogenesis. Therefore, we carried out a genetic and functional analysis of the Vpr variants from eight HIV-1-infected individuals from north India. The sequence analyses revealed that six of eight samples clustered with ancestral subtype C. Remarkably, five of these showed a conserved and region-specific L64P mutation, located in the predicted third α-helix. This change adversely affected their ability to activate the HIV-1 long terminal repeat promoter without compromising their ability to cause apoptosis. Bootscan, phylogenetic and SimPlot analysis of the remaining two samples (VprS2 and A6) revealed very interesting mosaic genomes derived from B, C and D subtypes. The N-terminal half of the VprS2 gene consisted of genomic segments derived from subtypes B/D, C and D but the C-terminal half was derived predominantly from subtype C. Interestingly the N-terminal half of sample A6 also showed similar B/D, C and D inter-subtype recombinant structure but the C-terminal half was entirely derived from the consensus B subtype. Multiple breakpoints in a short stretch of 291 nt encoding the Vpr gene strongly suggest that this region is a potential hot-spot for the formation of inter-subtype recombinants and also highlight the importance of the rapidly evolving HIV-1 epidemic in the north Indian region due to multiple genetic subtypes.
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Romani B, Glashoff R, Engelbrecht S. Molecular and phylogenetic analysis of HIV type 1 vpr sequences of South African strains. AIDS Res Hum Retroviruses 2009; 25:357-62. [PMID: 19271970 DOI: 10.1089/aid.2008.0251] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
HIV-1 subtype C is the prevalent subtype in South Africa, with non-C subtypes being sporadically detected. The accessory genes of subtype C have not been well studied in South Africa. In this study the HIV-1 vpr region of 58 strains was amplified, sequenced, and subtyped. Phylogenetic analysis characterized 54 strains as HIV-1 subtype C and 4 strains as HIV-1 subtype B. The amino acid sequence of the protein was also investigated. The overall amino acid sequence of Vpr was conserved as well as the motifs FPRPWL (34-39: IH1) and TYGDTW (49-54: IH2). The C-terminal was more variable. The importance of these motifs and variability needs to be addressed.
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Affiliation(s)
- Bizhan Romani
- Department of Pathology, Division of Medical Virology, University of Stellenbosch, Tygerberg 7505, South Africa
| | - Richard Glashoff
- Department of Pathology, Division of Medical Virology, University of Stellenbosch, Tygerberg 7505, South Africa
| | - Susan Engelbrecht
- Department of Pathology, Division of Medical Virology, University of Stellenbosch, Tygerberg 7505, South Africa
- National Health Laboratory Services (NHLS), Tygerberg 7505, South Africa
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16
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Srinivasan A, Ayyavoo V, Mahalingam S, Kannan A, Boyd A, Datta D, Kalyanaraman VS, Cristillo A, Collman RG, Morellet N, Sawaya BE, Murali R. A comprehensive analysis of the naturally occurring polymorphisms in HIV-1 Vpr: potential impact on CTL epitopes. Virol J 2008; 5:99. [PMID: 18721481 PMCID: PMC2553080 DOI: 10.1186/1743-422x-5-99] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2008] [Accepted: 08/23/2008] [Indexed: 12/20/2022] Open
Abstract
The enormous genetic variability reported in HIV-1 has posed problems in the treatment of infected individuals. This is evident in the form of HIV-1 resistant to antiviral agents, neutralizing antibodies and cytotoxic T lymphocytes (CTLs) involving multiple viral gene products. Based on this, it has been suggested that a comprehensive analysis of the polymorphisms in HIV proteins is of value for understanding the virus transmission and pathogenesis as well as for the efforts towards developing anti-viral therapeutics and vaccines. This study, for the first time, describes an in-depth analysis of genetic variation in Vpr using information from global HIV-1 isolates involving a total of 976 Vpr sequences. The polymorphisms at the individual amino acid level were analyzed. The residues 9, 33, 39, and 47 showed a single variant amino acid compared to other residues. There are several amino acids which are highly polymorphic. The residues that show ten or more variant amino acids are 15, 16, 28, 36, 37, 48, 55, 58, 59, 77, 84, 86, 89, and 93. Further, the variant amino acids noted at residues 60, 61, 34, 71 and 72 are identical. Interestingly, the frequency of the variant amino acids was found to be low for most residues. Vpr is known to contain multiple CTL epitopes like protease, reverse transcriptase, Env, and Gag proteins of HIV-1. Based on this, we have also extended our analysis of the amino acid polymorphisms to the experimentally defined and predicted CTL epitopes. The results suggest that amino acid polymorphisms may contribute to the immune escape of the virus. The available data on naturally occurring polymorphisms will be useful to assess their potential effect on the structural and functional constraints of Vpr and also on the fitness of HIV-1 for replication.
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Affiliation(s)
- Alagarsamy Srinivasan
- Department of Microbiology and Immunology, Thomas Jefferson University, Philadelphia, PA 19107, USA.
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17
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Wiegers K, Schwarck D, Reimer R, Bohn W. Activation of the glucocorticoid receptor releases unstimulated PBMCs from an early block in HIV-1 replication. Virology 2008; 375:73-84. [PMID: 18295813 DOI: 10.1016/j.virol.2008.01.037] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2007] [Revised: 10/19/2007] [Accepted: 01/19/2008] [Indexed: 10/22/2022]
Abstract
Infection of resting peripheral mononuclear blood cells (PBMCs) with HIV-1 is not productive due to a block prior to integration of the provirus into the host genome. Here we show that a unique restriction is determined by the status of the glucocorticoid receptor (GR). Proviral integration increases after addition of a GR ligand. The ligand dependent effect is confined to an early time period after infection and requires GR and the GR binding viral protein Vpr. Endogenous GR and transiently expressed Vpr are localized in the cytoplasm in unstimulated PMCs and comigrate into the nucleus upon ligand addition. Thus, the predominant cytoplasmic localization of GR seems to be a specific obstacle for HIV replication. Accordingly, efficient proviral integration in a cell line with a constitutive cytoplasmic GR requires addition of a GR ligand. The data suggest that steroids can overcome the restriction on HIV provirus formation and thereby increase the reservoir of virus producing cells.
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Affiliation(s)
- Klaus Wiegers
- Heinrich-Pette-Institut für Experimentelle Virologie und Immunologie an der Universität Hamburg, 20251 Hamburg, Germany.
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18
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Jacquot G, Le Rouzic E, David A, Mazzolini J, Bouchet J, Bouaziz S, Niedergang F, Pancino G, Benichou S. Localization of HIV-1 Vpr to the nuclear envelope: impact on Vpr functions and virus replication in macrophages. Retrovirology 2007; 4:84. [PMID: 18039376 PMCID: PMC2211753 DOI: 10.1186/1742-4690-4-84] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2007] [Accepted: 11/26/2007] [Indexed: 12/23/2022] Open
Abstract
Background HIV-1 Vpr is a dynamic protein that primarily localizes in the nucleus, but a significant fraction is concentrated at the nuclear envelope (NE), supporting an interaction between Vpr and components of the nuclear pore complex, including the nucleoporin hCG1. In the present study, we have explored the contribution of Vpr accumulation at the NE to the Vpr functions, including G2-arrest and pro-apoptotic activities, and virus replication in primary macrophages. Results In order to define the functional role of Vpr localization at the NE, we have characterized a set of single-point Vpr mutants, and selected two new mutants with substitutions within the first α-helix of the protein, Vpr-L23F and Vpr-K27M, that failed to associate with hCG1, but were still able to interact with other known relevant host partners of Vpr. In mammalian cells, these mutants failed to localize at the NE resulting in a diffuse nucleocytoplasmic distribution both in HeLa cells and in primary human monocyte-derived macrophages. Other mutants with substitutions in the first α-helix (Vpr-A30L and Vpr-F34I) were similarly distributed between the nucleus and cytoplasm, demonstrating that this helix contains the determinants required for localization of Vpr at the NE. All these mutations also impaired the Vpr-mediated G2-arrest of the cell cycle and the subsequent cell death induction, indicating a functional link between these activities and the Vpr accumulation at the NE. However, this localization is not sufficient, since mutations within the C-terminal basic region of Vpr (Vpr-R80A and Vpr-R90K), disrupted the G2-arrest and apoptotic activities without altering NE localization. Finally, the replication of the Vpr-L23F and Vpr-K27M hCG1-binding deficient mutant viruses was also affected in primary macrophages from some but not all donors. Conclusion These results indicate that the targeting of Vpr to the nuclear pore complex may constitute an early step toward Vpr-induced G2-arrest and subsequent apoptosis; they also suggest that Vpr targeting to the nuclear pore complex is not absolutely required, but can improve HIV-1 replication in macrophages.
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Affiliation(s)
- Guillaume Jacquot
- Institut Cochin, Université Paris Descartes, CNRS (UMR 8104), Paris, France.
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19
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Janket ML, DeRicco JS, Borowski L, Ayyavoo V. Human immunodeficiency virus (HIV-1) Vpr induced downregulation of NHE1 induces alteration in intracellular pH and loss of ERM complex in target cells. Virus Res 2007; 126:76-85. [PMID: 17349711 PMCID: PMC1950453 DOI: 10.1016/j.virusres.2007.01.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2006] [Revised: 01/28/2007] [Accepted: 01/30/2007] [Indexed: 11/30/2022]
Abstract
Human immunodeficiency virus type 1 (HIV-1) Vpr is known to dysregulate host cellular functions through its interaction with cellular proteins. Using a protein array we assessed Vpr-mediated differential regulation of host cellular proteins expression. Results demonstrated that Vpr differentially regulated host factors that are involved in functions, such as cell proliferation, differentiation and apoptosis. One of the most highly downregulated proteins attained was the sodium hydrogen exchanger, isoform 1 (NHE1), which showed a significant (60%) decrease in HIV-1 Vpr(+) virus infected cells as compared to HIV-1 Vpr(-) virus infected control. NHE1 downregulation further led to acidification of cells and was directly correlated with loss of ezrin, radixin and moesin (ERM) protein complex and decreased AKT phosphorylation. Vpr-mediated NHE1 dyregulation is in part through GR pathway as GR antagonist, mifepristone reversed Vpr-induced NHE1 downregulation.
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Affiliation(s)
- Michelle L. Janket
- Department of Infectious Diseases & Microbiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA
| | - Jeremy S. DeRicco
- Department of Infectious Diseases & Microbiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA
| | - LuAnn Borowski
- Department of Infectious Diseases & Microbiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA
| | - Velpandi Ayyavoo
- Department of Infectious Diseases & Microbiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA
- *Corresponding author: Velpandi Ayyavoo, Ph.D., University of Pittsburgh, Department of Infectious Diseases & Microbiology, 130 DeSoto Street, Pittsburgh, PA 15261, Phone: (412) 624-3070, Fax: (412) 383-8926,
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20
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Zhao RY, Elder RT, Bukrinsky M. Interactions of HIV-1 viral protein R with host cell proteins. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2007; 55:233-60. [PMID: 17586317 DOI: 10.1016/s1054-3589(07)55007-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Richard Y Zhao
- Department of Pathology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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21
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Wheeler EDA, Achim CL, Ayyavoo V. Immunodetection of human immunodeficiency virus type 1 (HIV-1) Vpr in brain tissue of HIV-1 encephalitic patients. J Neurovirol 2006; 12:200-10. [PMID: 16877301 DOI: 10.1080/13550280600827377] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Human immunodeficiency virus (HIV) encephalitis (HIVE), the most severe neurological complication associated with HIV-1 infection, leads to the onset of HIV-1-associated dementia (HAD). Several HIV-1 viral proteins have been implicated in HIVE-associated neurodegeneration. HIV-1 viral protein R (Vpr), a virion associated gene product known to induce apoptosis in nonproliferating cells, including neurons, is thought to contribute to the neuropathogenesis associated with HIVE. Though current research suggests that Vpr plays a significant role in neuropathogenesis, the presence of Vpr in the brain tissue of HIVE patients has not been assessed. Using a panel of HIVE patient brain tissue, the authors have shown that Vpr is present in detectable amounts in both the basal ganglia and frontal cortex of all HIVE brain tissue samples tested. Double immunofluorescence indicated that Vpr was found in the macrophages and neurons, but not in the astrocytes, of HIVE patients. These results for the first time show the presence of Vpr in vivo and further support the role of Vpr in neuropathogenesis.
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Affiliation(s)
- Elizabeth D A Wheeler
- Department of Infectious Diseases and Microbiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA
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22
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Schafer EA, Venkatachari NJ, Ayyavoo V. Antiviral effects of mifepristone on human immunodeficiency virus type-1 (HIV-1): targeting Vpr and its cellular partner, the glucocorticoid receptor (GR). Antiviral Res 2006; 72:224-32. [PMID: 16889838 DOI: 10.1016/j.antiviral.2006.06.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2006] [Revised: 05/16/2006] [Accepted: 06/19/2006] [Indexed: 10/24/2022]
Abstract
The HIV-1 viral protein R, Vpr, increases virus replication in T cells and is necessary for the optimal infection of primary monocytes/macrophages and other non-dividing cells. Vpr interacts with the cellular glucocorticoid receptor (GR) and transactivates the HIV-1 LTR through glucocorticoid response element (GRE), an event that can be blocked by the GR antagonist, mifepristone. Results demonstrated that Vpr-induced transactivation of the HIV-1 LTR was inhibited by mifepristone in a dose-dependent manner by >60% at a 10 microM concentration. Infectivity assays using X4 and R5 viruses demonstrated antiviral effects on a dose-dependent regimen of mifepristone. The effects of mifepristone were also tested in latently infected cells that could be activated with extracellular Vpr protein and results indicated specific inhibition of virus reactivation in the presence of this antagonist.
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MESH Headings
- Anti-HIV Agents/pharmacology
- Cell Line
- Cells, Cultured
- Dose-Response Relationship, Drug
- Gene Expression Regulation, Viral/drug effects
- Gene Products, vpr/metabolism
- HIV Core Protein p24/biosynthesis
- HIV Long Terminal Repeat/genetics
- HIV Long Terminal Repeat/physiology
- HIV-1/drug effects
- HIV-1/physiology
- HeLa Cells
- Humans
- Leukocytes, Mononuclear/cytology
- Leukocytes, Mononuclear/drug effects
- Leukocytes, Mononuclear/virology
- Macrophages/cytology
- Macrophages/drug effects
- Macrophages/virology
- Mifepristone/pharmacology
- Promoter Regions, Genetic
- Receptors, Glucocorticoid/metabolism
- Transcriptional Activation
- Virus Activation
- Virus Latency
- Virus Replication/drug effects
- vpr Gene Products, Human Immunodeficiency Virus
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Affiliation(s)
- Elizabeth A Schafer
- Department of Infectious Diseases & Microbiology, University of Pittsburgh, Graduate School of Public Health, 130 Desoto Street, Pittsburgh, PA 15261, USA
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23
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Varin A, Decrion AZ, Sabbah E, Quivy V, Sire J, Van Lint C, Roques BP, Aggarwal BB, Herbein G. Synthetic Vpr protein activates activator protein-1, c-Jun N-terminal kinase, and NF-kappaB and stimulates HIV-1 transcription in promonocytic cells and primary macrophages. J Biol Chem 2005; 280:42557-67. [PMID: 16243842 DOI: 10.1074/jbc.m502211200] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The human immunodeficiency virus (HIV) Vpr protein plays a critical role in AIDS pathogenesis, especially by allowing viral replication within nondividing cells such as mononuclear phagocytes. Most of the data obtained so far have been in experiments with endogenous Vpr protein; therefore the effects of extracellular Vpr protein remain largely unknown. We used synthetic Vpr protein to activate nuclear transcription factors activator protein-1 (AP-1) and NF-kappaB in the promonocytic cell line U937 and in primary macrophages. Synthetic HIV-1 Vpr protein activated AP-1, c-Jun N-terminal kinase, and MKK7 in both U937 cells and primary macrophages. Synthetic Vpr activated NF-kappaB in primary macrophages and to a lesser extent in U937 cells. Because synthetic Vpr activated AP-1 and NF-kappaB, which bind to the HIV-1 long terminal repeat, we investigated the effect of synthetic Vpr on HIV-1 replication. We observed that synthetic Vpr stimulated HIV-1 long terminal repeat in U937 cells and enhanced viral replication in chronically infected U1 promonocytic cells. Similarly, synthetic Vpr stimulated HIV-1 replication in acutely infected primary macrophages. Activation of transcription factors and enhancement of viral replication in U937 cells and primary macrophages were mediated by both the N-terminal and the C-terminal moieties of synthetic Vpr. Therefore, our results suggest that extracellular Vpr could fuel the progression of AIDS via stimulation of HIV-1 provirus present in such cellular reservoirs as mononuclear phagocytes in HIV-infected patients.
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Affiliation(s)
- Audrey Varin
- Department of Virology, EA3186, IFR133, Franche-Comté University, F-25030 Besançon, France
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24
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Cali L, Wang B, Mikhail M, Gill MJ, Beckthold B, Salemi M, Jans DA, Piller SC, Saksena NK. Evidence for host-driven selection of the HIV type 1 vpr gene in vivo during HIV disease progression in a transfusion-acquired cohort. AIDS Res Hum Retroviruses 2005; 21:728-33. [PMID: 16131313 DOI: 10.1089/aid.2005.21.728] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
An epidemiologically linked HIV-1-infected cohort, in which a nonprogressor donor infected two recipients who progressed to AIDS, was examined. Sequence analysis, over time, of HIV-1 vpr gene quasispecies from uncultured peripheral blood cells revealed an insertion of arginine at position 90 altering a highly conserved C-terminal motif, believed to play a role in Vpr nuclear targeting. Full genome analysis from each patient showed no gene defects in other gene regions, implying that the mutational selection was unique to the vpr gene. A detailed analysis of the vpr quasispecies showed very little amino acid diversity in the nonprogressing donor, whereas, following viral transmission, the amino acid diversity increased dramatically over time in tandem with disease progression in the two recipients. Although the R insertion at position 90 was present in all three individuals, the variable degree of additional amino acid changes over time may have influenced HIV disease in the nonprogressor donor and the two progressing recipients. These data provide the first evidence in favor of vpr gene evolution over time, which was host-driven. The status of the nonprogressing donor was consistent with a highly protective B-57 HLA type, which was absent in the two progressing recipients, implying a role for host HLA type and other immunologic selective pressures in vpr gene selection in vivo.
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Affiliation(s)
- Leon Cali
- Nuclear Signalling Laboratory, Department of Biochemistry and Molecular Biology, Monash University, Monash, VIC 3800, Australia
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