1
|
Love M, Samora L, Barker D, Zukosky P, Kummet N, Ahmad A, Bernhardt D, Tripathi M, Klotz S, Ahmad N. Genetic Analysis of HIV-1 vpr Sequences from HIV-Infected Older Patients on Long-Term Antiretroviral Therapy. Curr HIV Res 2022; 20:309-320. [PMID: 35792120 DOI: 10.2174/1570162x20666220705124341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 04/20/2022] [Accepted: 04/28/2022] [Indexed: 01/27/2023]
Abstract
BACKGROUND Many HIV-infected individuals have achieved undetectable viral load and increased CD4 T cell counts due to the success of Antiretroviral Therapy (ART). However, HIV persists in resting T cells, monocytes/macrophages and other quiescent cells. Furthermore, the HIV- 1 vpr accessory gene may play an important role in the persistence of HIV in these infected patients. OBJECTIVES Therefore, we characterized the HIV-1 vpr gene from PBMC DNA of 14 HIV-infected older patients on long-term ART with mostly undetectable viral load and increased CD4 T cell counts. METHODS Peripheral Blood Mononuclear Cells (PBMC) were isolated from 14 HIV-infected individuals, followed by extraction of genomic DNA, amplification of HIV-1 vpr gene by polymerase chain reaction (PCR), cloning of vpr gene in TOPO vector and characterization of correct size recombinant inserts containing vpr genes. An average of 13 clones were sequenced from each patient, followed by sequence analysis by bioinformatic tools. RESULTS Phylogenetic analysis of 182 vpr sequences demonstrated that the vpr sequences of each patient were well separated and discriminated from other patients' sequences and formed distinct clusters. The vpr sequences showed a low degree of viral heterogeneity, lower estimates of genetic diversity and about half of the patients' sequences were under positive selection pressure. While the majority of the vpr deduced amino acid sequences from most patients contained intact open reading frames, several sequences, mostly from two patients, had stop codons. Numerous patient-specific and common amino acid motifs were found in deduced vpr sequences. The functional domains required for vpr activity, including virion incorporation, nuclear import of pre-integration complex and cell cycle arrest, were generally conserved in most vpr sequences. Several of the known Cytotoxic T-lymphocytes (CTL) epitopes in vpr showed variation in our patients' sequences. CONCLUSION In summary, a low degree of genetic variability, conservation of functional domains and variations in CTL epitopes were the features of vpr sequences from the 14 HIV-infected older patients with controlled viremia on long-term ART.
Collapse
Affiliation(s)
- Maria Love
- Department of Immunobiology, College of Medicine, University of Arizona, Tucson, AZ 85721, Arizona, USA
| | - Luiza Samora
- Department of Immunobiology, College of Medicine, University of Arizona, Tucson, AZ 85721, Arizona, USA
| | - Danae Barker
- Department of Immunobiology, College of Medicine, University of Arizona, Tucson, AZ 85721, Arizona, USA
| | - Priya Zukosky
- Department of Immunobiology, College of Medicine, University of Arizona, Tucson, AZ 85721, Arizona, USA
| | - Nathan Kummet
- Department of Immunobiology, College of Medicine, University of Arizona, Tucson, AZ 85721, Arizona, USA
| | - Aasim Ahmad
- Department of Immunobiology, College of Medicine, University of Arizona, Tucson, AZ 85721, Arizona, USA
| | - Dana Bernhardt
- Department of Immunobiology, College of Medicine, University of Arizona, Tucson, AZ 85721, Arizona, USA
| | - Meghna Tripathi
- Department of Immunobiology, College of Medicine, University of Arizona, Tucson, AZ 85721, Arizona, USA
| | - Stephen Klotz
- Department of Medicine, College of Medicine, University of Arizona, Tucson, AZ 85721, Arizona, USA
| | - Nafees Ahmad
- Department of Immunobiology, College of Medicine, University of Arizona, Tucson, AZ 85721, Arizona, USA
| |
Collapse
|
2
|
Mifsud S, Gauci Z, Gruppetta M, Mallia Azzopardi C, Fava S. Adrenal insufficiency in HIV/AIDS: a review. Expert Rev Endocrinol Metab 2021; 16:351-362. [PMID: 34521306 DOI: 10.1080/17446651.2021.1979393] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 08/24/2021] [Indexed: 01/11/2023]
Abstract
INTRODUCTION Adrenal insufficiency (AI) is one of the most common potentially life-threatening endocrine complications in people living with human immunodeficiency virus (PLHIV) infection and acquired immunodeficiency syndrome (AIDS). AREAS COVERED In this review, the authors explore the definitions of relative AI, primary AI, secondary AI and peripheral glucocorticoid resistance in PLHIV. It also focuses on the pathophysiology, etiology, diagnosis and management of this endocrinopathy in PLHIV. A literature review was conducted through Medline and Google Scholar search on the subject. EXPERT OPINION Physicians need to be aware of the endocrinological implications of HIV infection and its treatment, especially CYP3A4 enzyme inhibitors. A high index of clinical suspicion is needed in the detection of AI, especially in PLHIV, as it may present insidiously with nonspecific signs and symptoms and may be potentially life threatening if left untreated. Patients with overt primary and secondary AI require glucocorticoid replacement therapy. Overt primary AI also necessitates mineralocorticoid replacement. On the other hand, the management of relative AI remains controversial. In order to reduce the risk of adrenal crisis during periods of stress, the short-term use of glucocorticoids may be necessary in relative AI.
Collapse
Affiliation(s)
- Simon Mifsud
- Department of Diabetes, Endocrinology and General Medicine, Mater Dei Hospital, Msida, Malta
| | - Zachary Gauci
- Department of Diabetes, Endocrinology and General Medicine, Mater Dei Hospital, Msida, Malta
| | - Mark Gruppetta
- Department of Diabetes, Endocrinology and General Medicine, Mater Dei Hospital, Msida, Malta
| | | | - Stephen Fava
- Department of Diabetes, Endocrinology and General Medicine, Mater Dei Hospital, Msida, Malta
| |
Collapse
|
3
|
HIV-1 Tat Protein Promotes Neuroendocrine Dysfunction Concurrent with the Potentiation of Oxycodone's Psychomotor Effects in Female Mice. Viruses 2021; 13:v13050813. [PMID: 33946474 PMCID: PMC8147167 DOI: 10.3390/v13050813] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Revised: 04/23/2021] [Accepted: 04/27/2021] [Indexed: 02/06/2023] Open
Abstract
Human immunodeficiency virus (HIV) is associated with neuroendocrine dysfunction which may contribute to co-morbid stress-sensitive disorders. The hypothalamic-pituitary-adrenal (HPA) or -gonadal (HPG) axes are perturbed in up to 50% of HIV patients. The mechanisms are not known, but we have found the HIV-1 trans-activator of transcription (Tat) protein to recapitulate the clinical phenotype in male mice. We hypothesized that HPA and/or HPG dysregulation contributes to Tat-mediated interactions with oxycodone, an opioid often prescribed to HIV patients, in females. Female mice that conditionally-expressed the Tat1-86 protein [Tat(+) mice] or their counterparts that did not [Tat(-) control mice] were exposed to forced swim stress (or not) and behaviorally-assessed for motor and anxiety-like behavior. Some mice had glucocorticoid receptors (GR) or corticotropin-releasing factor receptors (CRF-R) pharmacologically inhibited. Some mice were ovariectomized (OVX). As seen previously in males, Tat elevated basal corticosterone levels and potentiated oxycodone's psychomotor activity in females. Unlike males, females did not demonstrate adrenal insufficiency and oxycodone potentiation was not regulated by GRs or CRF-Rs. Rather OVX attenuated Tat/oxycodone interactions. Either Tat or oxycodone increased anxiety-like behavior and their combination increased hypothalamic allopregnanolone. OVX increased basal hypothalamic allopregnanolone and obviated Tat or oxycodone-mediated fluctuations. Together, these data provide further evidence for Tat-mediated dysregulation of the HPA axis and reveal the importance of HPG axis regulation in females. HPA/HPG disruption may contribute vulnerability to affective and substance use disorders.
Collapse
|
4
|
Schmitt K, Curlin J, Remling-Mulder L, Moriarty R, Goff K, O'Connor S, Stenglein M, Marx P, Akkina R. Cross-Species Transmission and Evolution of SIV Chimpanzee Progenitor Viruses Toward HIV-1 in Humanized Mice. Front Microbiol 2020; 11:1889. [PMID: 32849468 PMCID: PMC7432304 DOI: 10.3389/fmicb.2020.01889] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 07/20/2020] [Indexed: 12/22/2022] Open
Abstract
The genetic evolution of HIV-1 from its progenitor virus SIV following cross-species transmission is not well understood. Here we simulated the SIVcpz initial transmission to humans using humanized mice and followed the viral evolution during serial passages lasting more than a year. All three SIVcpz progenitor viruses used, namely LB715 and MB897 (group M) as well as EK505 (group N) readily infected hu-mice resulting in chronic viremia. Viral loads increased progressively to higher set-points and the CD4+ T cell decline became more pronounced by the end of the second serial passage indicating viral adaptation and increased pathogenicity. Viral genomes sequenced at different time points revealed many non-synonymous variants not previously reported that occurred throughout the viral genome, including the gag, pol, env, and nef genes. These results shed light on the potential changes that the SIVcpz genome had undergone during the initial stages of human infection and subsequent spread.
Collapse
Affiliation(s)
- Kimberly Schmitt
- Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO, United States
| | - James Curlin
- Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO, United States
| | - Leila Remling-Mulder
- Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO, United States
| | - Ryan Moriarty
- Department of Pathology and Laboratory Medicine, School of Medicine and Public Health, University of Wisconsin, Madison, WI, United States
| | - Kelly Goff
- Tulane National Primate Research Center, Tulane University, Covington, LA, United States
| | - Shelby O'Connor
- Department of Pathology and Laboratory Medicine, School of Medicine and Public Health, University of Wisconsin, Madison, WI, United States
| | - Mark Stenglein
- Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO, United States
| | - Preston Marx
- Tulane National Primate Research Center, Tulane University, Covington, LA, United States.,Department of Tropical Medicine, School of Public Health & Tropical Medicine, Tulane University, New Orleans, LA, United States
| | - Ramesh Akkina
- Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO, United States
| |
Collapse
|
5
|
Marquette A, Leborgne C, Schartner V, Salnikov E, Bechinger B, Kichler A. Peptides derived from the C-terminal domain of HIV-1 Viral Protein R in lipid bilayers: Structure, membrane positioning and gene delivery. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183149. [PMID: 31816324 DOI: 10.1016/j.bbamem.2019.183149] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 12/03/2019] [Accepted: 12/04/2019] [Indexed: 12/19/2022]
Abstract
Viral protein R (Vpr) is a small accessory protein of 96 amino acids that is present in Human and simian immunodeficiency viruses. Among the very different properties that Vpr possesses we can find cell penetrating capabilities. Based on this and on its capacity to interact with nucleic acids we previously investigated the DNA transfection properties of Vpr and subfragments thereof. We found that fragments of the C-terminal helical domain of Vpr are able to deliver efficiently plasmid DNA into different cell lines. As the amphipathic helix may play a role in the interactions with membranes, we investigated whether insertion of a proline residue in the α-helix modifies the transfection properties of Vpr. Unexpectedly, we found that the resulting Vpr55-82 Pro70 peptide was even more efficient than wild type Vpr55-82 in the gene delivery assays. Using circular dichroism, light scattering and solid-state NMR techniques, we characterized the secondary structure and interactions of Vpr and several mutants with model membranes. A model is proposed where the proline shifts the dissociation equilibrium of the peptide-cargo complex and thereby its endosomal release.
Collapse
Affiliation(s)
- Arnaud Marquette
- Université de Strasbourg, CNRS, UMR7177, IUF, Institut de Chimie, 4, Rue Blaise Pascal, 67070 Strasbourg, France
| | | | - Vanessa Schartner
- Laboratoire de Conception et Application de Molécules Bioactives UMR7199 CNRS - Université de Strasbourg, Faculté de Pharmacie, 67401 Illkirch, France
| | - Evgeniy Salnikov
- Université de Strasbourg, CNRS, UMR7177, IUF, Institut de Chimie, 4, Rue Blaise Pascal, 67070 Strasbourg, France
| | - Burkhard Bechinger
- Université de Strasbourg, CNRS, UMR7177, IUF, Institut de Chimie, 4, Rue Blaise Pascal, 67070 Strasbourg, France.
| | - Antoine Kichler
- Laboratoire de Conception et Application de Molécules Bioactives UMR7199 CNRS - Université de Strasbourg, Faculté de Pharmacie, 67401 Illkirch, France.
| |
Collapse
|
6
|
Womersley JS, Clauss LB, Varathan O, Engelbrecht S, Hemmings SMJ, Seedat S, Spies G. The effect of childhood trauma, ApoE genotype and HIV-1 viral protein R variants on change in cognitive performance. BMC Res Notes 2019; 12:828. [PMID: 31881924 PMCID: PMC6935155 DOI: 10.1186/s13104-019-4869-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 12/19/2019] [Indexed: 11/10/2022] Open
Abstract
OBJECTIVE Gene-environment interactions contribute to the development of HIV-associated neurocognitive disorders. We examined whether childhood trauma, apolipoprotein E isoforms and viral protein R (Vpr) variants were associated with change in cognitive performance. Seventy-three seropositive women completed neuropsychological assessments at baseline and 1-year follow-up. We conducted genetic analyses using DNA obtained from blood and calculated risk scores based on Vpr amino acid 37, 41 and 55 variants that were previously associated with cognitive performance. RESULTS Global cognitive scores declined significantly over the 1-year study period (p = 0.029). A reduction in global cognitive scores was associated with childhood trauma experience (p = 0.039).
Collapse
Affiliation(s)
- Jacqueline S Womersley
- Department of Psychiatry, Faculty of Medicine and Health Sciences, Stellenbosch University, Francie van Zijl Drive, Tygerberg, 7505, South Africa.
- South African Medical Research Council/Stellenbosch University Genomics of Brain Disorders Research Unit, Francie van Zijl Drive, Tygerberg, 7505, South Africa.
| | - Lara B Clauss
- Department of Psychiatry, Faculty of Medicine and Health Sciences, Stellenbosch University, Francie van Zijl Drive, Tygerberg, 7505, South Africa
- Joint Master in Neuroscience, Faculty of Life Sciences, University of Strasbourg, Strasbourg, France
| | - Olivette Varathan
- Division of Medical Virology, Faculty of Medicine and Health Sciences, Stellenbosch University, Francie van Zijl Drive, Tygerberg, 7505, South Africa
| | - Susan Engelbrecht
- Division of Medical Virology, Faculty of Medicine and Health Sciences, Stellenbosch University, Francie van Zijl Drive, Tygerberg, 7505, South Africa
- National Health Laboratory Services (NHLS), Tygerberg Coastal, Tygerberg, Western Cape Region, South Africa
| | - Sian M J Hemmings
- Department of Psychiatry, Faculty of Medicine and Health Sciences, Stellenbosch University, Francie van Zijl Drive, Tygerberg, 7505, South Africa
- South African Medical Research Council/Stellenbosch University Genomics of Brain Disorders Research Unit, Francie van Zijl Drive, Tygerberg, 7505, South Africa
| | - Soraya Seedat
- Department of Psychiatry, Faculty of Medicine and Health Sciences, Stellenbosch University, Francie van Zijl Drive, Tygerberg, 7505, South Africa
- South African Medical Research Council/Stellenbosch University Genomics of Brain Disorders Research Unit, Francie van Zijl Drive, Tygerberg, 7505, South Africa
| | - Georgina Spies
- Department of Psychiatry, Faculty of Medicine and Health Sciences, Stellenbosch University, Francie van Zijl Drive, Tygerberg, 7505, South Africa
- South African Medical Research Council/Stellenbosch University Genomics of Brain Disorders Research Unit, Francie van Zijl Drive, Tygerberg, 7505, South Africa
| |
Collapse
|
7
|
Abstract
HIV infection and antiretroviral therapy (ART) treatment exert diverse effects on adipocytes and stromal-vascular fraction cells, leading to changes in adipose tissue quantity, distribution, and energy storage. A HIV-associated lipodystrophic condition was recognized early in the epidemic, characterized by clinically apparent changes in subcutaneous, visceral, and dorsocervical adipose depots. Underlying these changes is altered adipose tissue morphology and expression of genes central to adipocyte maturation, regulation, metabolism, and cytokine signaling. HIV viral proteins persist in circulation and locally within adipose tissue despite suppression of plasma viremia on ART, and exposure to these proteins impairs preadipocyte maturation and reduces adipocyte expression of peroxisome proliferator-activated receptor gamma (PPAR-γ) and other genes involved in cell regulation. Several early nucleoside reverse transcriptase inhibitor and protease inhibitor antiretroviral drugs demonstrated substantial adipocyte toxicity, including reduced mitochondrial DNA content and respiratory chain enzymes, reduced PPAR-γ and other regulatory gene expression, and increased proinflammatory cytokine production. Newer-generation agents, such as integrase inhibitors, appear to have fewer adverse effects. HIV infection also alters the balance of CD4+ and CD8+ T cells in adipose tissue, with effects on macrophage activation and local inflammation, while the presence of latently infected CD4+ T cells in adipose tissue may constitute a protected viral reservoir. This review provides a synthesis of the literature on how HIV virus, ART treatment, and host characteristics interact to affect adipose tissue distribution, immunology, and contribution to metabolic health, and adipocyte maturation, cellular regulation, and energy storage. © 2017 American Physiological Society. Compr Physiol 7:1339-1357, 2017.
Collapse
Affiliation(s)
- John R Koethe
- Division of Infectious Diseases, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| |
Collapse
|
8
|
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.
Collapse
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.
| |
Collapse
|
9
|
Guichard A, Humbert P, Tissot M, Muret P, Courderot-Masuyer C, Viennet C. Effects of topical corticosteroids on cell proliferation, cell cycle progression and apoptosis: in vitro comparison on HaCaT. Int J Pharm 2014; 479:422-9. [PMID: 25556056 DOI: 10.1016/j.ijpharm.2014.12.066] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Accepted: 12/26/2014] [Indexed: 11/27/2022]
Abstract
Topical-corticosteroids are mainly used for the treatment of inflammatory or hyperproliferative skin diseases. The in vivo assay to rank topical-corticosteroids potency, based on the skin blanching, is not adapted to compare their anti-proliferative efficacy. We have compared the antiproliferative effect of six topical-corticosteroids on a model of hyperproliferant keratinocytes (HaCaT). Betamethasone-dipropionate; clobetasol-propionate; betamethasone-valerate; desonide; hydrocortisone-butyrate and hydrocortisone-base, at different concentrations (10(-8)-10(-4)M) have been compared. HaCaT proliferation has been evaluated by MTT-assay and the mechanism of the death was evaluated by annexin V/propidium iodide staining and cell cycle phases analysis. Topical corticosteroids reduced cell growth in a dose-dependent manner. At 10(-4)M, betamethasone dipropionate was the most antiproliferative compound while hydrocortisone-butyrate was the less. Hydrocortisone-base which is usually considered as the less potent topical-corticosteroids showed a clear cytotoxic effect. Betamethasone-dipropionate and betamethasone-valerate induced more apoptosis than necrosis whereas the reverse has been observed for other topical-corticosteroids. All topical-corticosteroids, except clobetasol-propionate, arrested cell cycle mainly in G2-phase. Clobetasol-propionate arrested cell cycle in S-phase population. At 10(-8)M, topical-corticosteroids induced HaCaT proliferation. In terms of antiproliferative effect at 10(-4)M, we propose to rank topical corticosteroids as follow: betamethasone-dipropionate>desonide≥betamethasone-valerate=hydrocortisone-base=clobetasol-propionate>hydrocortisone-butyrate. This classification differs from the current ranking, based on the vasoconstrictive effect, but is more adapted for hyperproliferative disease treatment.
Collapse
Affiliation(s)
- Alexandre Guichard
- Research and Studies Center on the Integument (CERT), Department of Dermatology, Clinical Investigation Center (CIC INSERM 1431), Besançon University Hospital, France; Engineering and Cutaneous Biology Laboratory, INSERM UMR 1098, SFR FED 4234, University of Franche-Comte, Besançon, France.
| | - Philippe Humbert
- Research and Studies Center on the Integument (CERT), Department of Dermatology, Clinical Investigation Center (CIC INSERM 1431), Besançon University Hospital, France; Engineering and Cutaneous Biology Laboratory, INSERM UMR 1098, SFR FED 4234, University of Franche-Comte, Besançon, France.
| | - Marion Tissot
- Engineering and Cutaneous Biology Laboratory, INSERM UMR 1098, SFR FED 4234, University of Franche-Comte, Besançon, France.
| | - Patrice Muret
- Engineering and Cutaneous Biology Laboratory, INSERM UMR 1098, SFR FED 4234, University of Franche-Comte, Besançon, France.
| | | | - Céline Viennet
- Engineering and Cutaneous Biology Laboratory, INSERM UMR 1098, SFR FED 4234, University of Franche-Comte, Besançon, France.
| |
Collapse
|
10
|
Webster Marketon JI, Corry J, Teng MN. The respiratory syncytial virus (RSV) nonstructural proteins mediate RSV suppression of glucocorticoid receptor transactivation. Virology 2014; 449:62-9. [PMID: 24418538 PMCID: PMC3904736 DOI: 10.1016/j.virol.2013.11.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Revised: 07/12/2013] [Accepted: 11/06/2013] [Indexed: 12/22/2022]
Abstract
Respiratory syncytial virus (RSV)-induced bronchiolitis in infants is not responsive to glucocorticoids. We have shown that RSV infection impairs glucocorticoid receptor (GR) function. In this study, we have investigated the mechanism by which RSV impairs GR function. We have shown that RSV repression of GR-induced transactivation is not mediated through a soluble autocrine factor. Knock-down of mitochondrial antiviral signaling protein (MAVS), but not retinoic acid-inducible gene 1 (RIG-I) or myeloid differentiation primary response gene 88 (MyD88), impairs GR-mediated gene activation even in mock-infected cells. Over-expression of the RSV nonstructural protein NS1, but not NS2, impairs glucocorticoid-induced transactivation and viruses deleted in NS1 and/or NS2 are unable to repress glucocorticoid-induction of the known GR regulated gene glucocorticoid-inducible leucine zipper (GILZ). These data suggest that the RSV nonstructural proteins mediate RSV repression of GR-induced transactivation and that inhibition of the nonstructural proteins may be a viable target for therapy against RSV-related disease.
Collapse
Affiliation(s)
- Jeanette I Webster Marketon
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Internal Medicine, Wexner Medical Center at The Ohio State University, Columbus, OH 43210, United States; Institute for Behavioral Medicine Research, Wexner Medical Center at The Ohio State University, Columbus, OH 43210, United States.
| | - Jacqueline Corry
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Internal Medicine, Wexner Medical Center at The Ohio State University, Columbus, OH 43210, United States.
| | - Michael N Teng
- Joy McCann Culverhouse Airway Disease Research Center, Division of Allergy and Immunology, Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, United States
| |
Collapse
|
11
|
Casey Klockow L, Sharifi HJ, Wen X, Flagg M, Furuya AKM, Nekorchuk M, de Noronha CMC. The HIV-1 protein Vpr targets the endoribonuclease Dicer for proteasomal degradation to boost macrophage infection. Virology 2013; 444:191-202. [PMID: 23849790 DOI: 10.1016/j.virol.2013.06.010] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Accepted: 06/09/2013] [Indexed: 12/13/2022]
Abstract
The HIV-1 protein Vpr enhances macrophage infection, triggers G2 cell cycle arrest, and targets cells for NK-cell killing. Vpr acts through the CRL4(DCAF1) ubiquitin ligase complex to cause G2 arrest and trigger expression of NK ligands. Corresponding ubiquitination targets have not been identified. UNG2 and SMUG1 are the only known substrates for Vpr-directed depletion through CRL4(DCAF1). Here we identify the endoribonuclease Dicer as a target of HIV-1 Vpr-directed proteasomal degradation through CRL4(DCAF1). We show that HIV-1 Vpr inhibits short hairpin RNA function as expected upon reduction of Dicer levels. Dicer inhibits HIV-1 replication in T cells. We demonstrate that Dicer also restricts HIV-1 replication in human monocyte-derived macrophages (MDM) and that reducing Dicer expression in MDMs enhances HIV-1 infection in a Vpr-dependent manner. Our results support a model in which Vpr complexes with human Dicer to boost its interaction with the CRL4(DCAF1) ubiquitin ligase complex and its subsequent degradation.
Collapse
Affiliation(s)
- Laurieann Casey Klockow
- Center for Immunology and Microbial Disease, Albany Medical College, 47 New Scotland Avenue, Albany, NY 12208, USA
| | | | | | | | | | | | | |
Collapse
|
12
|
Tomasicchio M, Avenant C, Du Toit A, Ray RM, Hapgood JP. The progestin-only contraceptive medroxyprogesterone acetate, but not norethisterone acetate, enhances HIV-1 Vpr-mediated apoptosis in human CD4+ T cells through the glucocorticoid receptor. PLoS One 2013; 8:e62895. [PMID: 23658782 PMCID: PMC3643923 DOI: 10.1371/journal.pone.0062895] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Accepted: 03/26/2013] [Indexed: 12/25/2022] Open
Abstract
The glucocorticoid receptor (GR) regulates several physiological functions, including immune function and apoptosis. The HIV-1 virus accessory protein, viral protein R (Vpr), can modulate the transcriptional response of the GR. Glucocorticoids (GCs) and Vpr have been reported to induce apoptosis in various cells, including T-cells. We have previously shown that the injectable contraceptive, medroxyprogesterone acetate (MPA) is a partial to full agonist for the GR, unlike norethisterone acetate (NET-A). We investigated the functional cross talk between the GR and Vpr in inducing apoptosis in CD4(+) T-cells, in the absence and presence of GCs and these progestins, as well as progesterone. By using flow cytometry, we show that, in contrast to NET-A and progesterone, the synthetic GR ligand dexamethasone (Dex), cortisol and MPA induce apoptosis in primary CD4(+) T-cells. Furthermore, the C-terminal part of the Vpr peptide, or HIV-1 pseudovirus, together with Dex or MPA further increased the apoptotic phenotype, unlike NET-A and progesterone. By a combination of Western blotting, PCR and the use of receptor- selective agonists, we provide evidence that the GR and the estrogen receptor are the only steroid receptors expressed in peripheral blood mononuclear cells. These results, together with the findings that RU486, a GR antagonist, prevents Dex-, MPA- and Vpr-mediated apoptosis, provide evidence for the first time that GR agonists or partial agonists increase apoptosis in primary CD4(+) T-cells via the GR. We show that apoptotic induction involves differential expression of key apoptotic genes by both Vpr and GCs/MPA. This work suggests that contraceptive doses of MPA but not NET-A or physiological doses of progesterone could potentially accelerate depletion of CD4(+) T-cells in a GR-dependent fashion in HIV-1 positive women, thereby contributing to immunodeficiency. The results imply that choice of progestin used in contraception may be critical to susceptibility and progression of diseases such as HIV-1.
Collapse
Affiliation(s)
- Michele Tomasicchio
- Department of Molecular and Cell Biology, University of Cape Town, Cape Town, Western Province, South Africa
| | - Chanel Avenant
- Department of Molecular and Cell Biology, University of Cape Town, Cape Town, Western Province, South Africa
| | - Andrea Du Toit
- Department of Molecular and Cell Biology, University of Cape Town, Cape Town, Western Province, South Africa
| | - Roslyn M. Ray
- Department of Molecular and Cell Biology, University of Cape Town, Cape Town, Western Province, South Africa
| | - Janet P. Hapgood
- Department of Molecular and Cell Biology, University of Cape Town, Cape Town, Western Province, South Africa
| |
Collapse
|
13
|
Fuchs S, Nguyen HD, Phan TTP, Burton MF, Nieto L, de Vries-van Leeuwen IJ, Schmidt A, Goodarzifard M, Agten SM, Rose R, Ottmann C, Milroy LG, Brunsveld L. Proline primed helix length as a modulator of the nuclear receptor-coactivator interaction. J Am Chem Soc 2013; 135:4364-71. [PMID: 23437920 DOI: 10.1021/ja311748r] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Nuclear receptor binding to coactivator proteins is an obligate first step in the regulation of gene transcription. Nuclear receptors preferentially bind to an LXXLL peptide motif which is highly conserved throughout the 300 or so natural coactivator proteins. This knowledge has shaped current understanding of this fundamental protein-protein interaction, and continues to inspire the search for new drug therapies. However, sequence specificity beyond the LXXLL motif and the molecular functioning of flanking residues still requires urgent addressing. Here, ribosome display has been used to reassess the estrogen receptor for new and enlarged peptide recognition motifs, leading to the discovery of a potent and highly evolved PXLXXLLXXP binding consensus. Molecular modeling and X-ray crystallography studies have provided the molecular insights on the role of the flanking prolines in priming the length of the α-helix and enabling optimal interactions of the α-helix dipole and its surrounding amino acids with the surface charge clamp and the receptor activation function 2. These findings represent new structural parameters for modulating the nuclear receptor-coactivator interaction based on linear sequences of proteinogenic amino acids and for the design of chemically modified inhibitors.
Collapse
Affiliation(s)
- Sascha Fuchs
- Laboratory of Chemical Biology, Department of Biomedical Engineering, Technische Universiteit Eindhoven, Den Dolech 2, 5612 AZ Eindhoven, The Netherlands
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
14
|
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]
|
15
|
Miller MS, Mymryk JS. An unhealthy relationship: viral manipulation of the nuclear receptor superfamily. Future Microbiol 2011; 6:999-1019. [PMID: 21958141 DOI: 10.2217/fmb.11.80] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The nuclear receptor (NR) superfamily is a diverse group of over 50 proteins whose function is to regulate the transcription of a vast array of cellular genes. These proteins are able to tune transcription over an extremely dynamic range due to the fact that they may act as either transcriptional activators or repressors depending on promoter context and ligand status. Due to these unique properties, diverse families of viruses have evolved strategies to exploit NRs in order to regulate expression of their own genes and to optimize the cellular milieu to facilitate the viral lifecycle. While the specific NRs targeted by these viruses vary, the strategies used to target them are common. This is accomplished at the cis-level by incorporation of nuclear receptor response elements into the viral genome and at the trans-level by viral proteins that target NRs directly or indirectly to modulate their function. The specific NR(s) targeted by a particular virus are likely to be reflective of the tissue tropism of the virus in question. Thus, the essential role played by NRs in the replication cycles of such diverse viruses underscores the importance of understanding their functions in the context of specific infections. This knowledge will allow appropriate considerations to be made when treating infected individuals with hormone-associated diseases and will potentially assist in the rational design of novel antiviral therapeutics.
Collapse
Affiliation(s)
- Matthew S Miller
- Department of Microbiology & Immunology, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, Ontario, N6A 5C1, Canada
| | | |
Collapse
|
16
|
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.
Collapse
|
17
|
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.
Collapse
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
| | | |
Collapse
|
18
|
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.
Collapse
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
| | | |
Collapse
|
19
|
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.
Collapse
Affiliation(s)
- Janet Patricia Hapgood
- Department of Molecular and Cell Biology, University of Cape Town, Rondebosch 7701, South Africa.
| | | |
Collapse
|
20
|
Abstract
Like most viral regulatory proteins, HIV-1 Vpr and homologous proteins from primate lentiviruses are small and multifunctional. They are associated with a plethora of effects and functions, including induction of cell cycle arrest in the G(2) phase, induction of apoptosis, transactivation, enhancement of the fidelity of reverse transcription, and nuclear import of viral DNA in macrophages and other nondividing cells. This review focuses on the cellular proteins that have been reported to interact with Vpr and their significance with respect to the known functions and effects of Vpr on cells and on viral replication.
Collapse
Affiliation(s)
- Vicente Planelles
- Division of Cell Biology and Immunology, Department of Pathology, University of Utah School of Medicine, 15 North Medical Drive East #2100-Room 2520, Salt Lake City, Utah 84112, USA.
| | | |
Collapse
|
21
|
Cotter EJ, Mallon PW, Doran PP. Is PPARγ a prospective player in HIV-1-associated bone disease? PPAR Res 2009; 2009:421376. [PMID: 19325916 PMCID: PMC2659551 DOI: 10.1155/2009/421376] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2008] [Revised: 12/03/2008] [Accepted: 01/21/2009] [Indexed: 12/13/2022] Open
Abstract
Currently infection with the human immunodeficiency virus-1 (HIV-1) is in most instances a chronic disease that can be controlled by effective antiretroviral therapy (ART). However, chronic use of ART has been associated with a number of toxicities; including significant reductions in bone mineral density (BMD) and disorders of the fat metabolism. The peroxisome proliferator-activated receptor γ (PPARγ) transcription factor is vital for the development and maintenance of mature and developing adipocytes. Alterations in PPARγ expression have been implicated as a factor in the mechanism of HIV-1-associated lipodystrophy. Both reduced BMD and lipodystrophy have been well described as complications of HIV-1 infection and treatment, and a question remains as to their interdependence. Interestingly, both adipocytes and osteoblasts are derived from a common precursor cell type; the mesenchymal stem cell. The possibility that dysregulation of PPARγ (and the subsequent effect on both osteoblastogenesis and adipogenesis) is a contributory factor in the lipid- and bone-abnormalities observed in HIV-1 infection and treatment has also been investigated. This review deals with the hypothesis that dysregulation of PPARγ may underpin the bone abnormalities associated with HIV-1 infection, and treats the current knowledge and prospective developments, in our understanding of PPARγ involvement in HIV-1-associated bone disease.
Collapse
Affiliation(s)
- Eoin J Cotter
- Clinical Research Center, University College Dublin, Belfield, 4 Dublin, Ireland.
| | | | | |
Collapse
|
22
|
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.
Collapse
Affiliation(s)
- Alagarsamy Srinivasan
- Department of Microbiology and Immunology, Thomas Jefferson University, Philadelphia, PA 19107, USA.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
23
|
Andersen JL, Le Rouzic E, Planelles V. HIV-1 Vpr: mechanisms of G2 arrest and apoptosis. Exp Mol Pathol 2008; 85:2-10. [PMID: 18514189 DOI: 10.1016/j.yexmp.2008.03.015] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2007] [Accepted: 03/04/2008] [Indexed: 02/05/2023]
Abstract
Since the first isolation of HIV-1 from a patient with generalized lymphadenopathy in 1983, great progress has been made in understanding the viral life cycle and the functional nuances of each of the nine genes encoded by HIV-1. Considerable attention has been paid to four small HIV-1 open reading frames, vif, vpr, vpu and nef. These genes were originally termed "accessory" because their deletion failed to completely disable viral replication in vitro. More than twenty years after the cloning and sequencing of HIV-1, a great deal of information is available regarding the multiple functions of the accessory proteins and it is well accepted that, collectively, these gene products modulate the host cell biology to favor viral replication, and that they are largely responsible for the pathogenesis of HIV-1. Expression of Vpr, in particular, leads to cell cycle arrest in G(2), followed by apoptosis. Here we summarize our current understanding of Vpr biology with a focus on Vpr-induced G(2) arrest and apoptosis.
Collapse
Affiliation(s)
- Joshua L Andersen
- Center for the Study of Aging and Human Development, Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA
| | | | | |
Collapse
|
24
|
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.
Collapse
Affiliation(s)
- Klaus Wiegers
- Heinrich-Pette-Institut für Experimentelle Virologie und Immunologie an der Universität Hamburg, 20251 Hamburg, Germany.
| | | | | | | |
Collapse
|
25
|
Xiao Y, Chen G, Richard J, Rougeau N, Li H, Seidah NG, Cohen EA. Cell-surface processing of extracellular human immunodeficiency virus type 1 Vpr by proprotein convertases. Virology 2007; 372:384-97. [PMID: 18061232 DOI: 10.1016/j.virol.2007.10.036] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2007] [Revised: 09/27/2007] [Accepted: 10/30/2007] [Indexed: 10/22/2022]
Abstract
Increasing evidence suggests that extracellular Vpr could contribute to HIV pathogenesis through its effect on bystander cells. Soluble forms of Vpr have been detected in the sera and cerebrospinal fluids of HIV-1-infected patients, and in vitro studies have implicated extracellular Vpr as an effector of cellular responses, including G2 arrest, apoptosis and induction of cytokines and chemokines production, presumably through its ability to transduce into multiple cell types. However, the mechanism underlying Vpr release from HIV-1-producing cells remains undefined and the biological modifications that the extracellular protein may undergo are largely unknown. We provide evidence indicating that soluble forms of Vpr are present in the extracellular medium of HIV-1-producing cells. Release of Vpr in the extracellular medium did not originate from decaying or disrupted HIV-1 virions that package Vpr but rather appeared associated with HIV-1-mediated cytopathicity. Interestingly, Vpr was found to undergo proteolytic processing at a very well conserved proprotein convertase (PC) cleavage site, R(85)QRR(88) downward arrow, located within the functionally important C-terminal arginine-rich domain of the protein. Vpr processing occurred extracellularly upon close contact to cells and most likely involved a cell surface-associated PC. Consistently, PC inhibitors suppressed Vpr processing, while expression of extracellular matrix-associated PC5 and PACE4 enhanced Vpr cleavage. PC-mediated processing of extracellular Vpr led to the production of a truncated Vpr product that was defective for the induction of cell cycle arrest and apoptosis when expressed in human cells. Collectively, these results suggest that cell surface processing of extracellular Vpr by PCs might regulate the levels of active soluble Vpr.
Collapse
Affiliation(s)
- Yong Xiao
- Laboratory of Human Retrovirology, Institut de recherches cliniques de Montréal, Montreal, Quebec, Canada
| | | | | | | | | | | | | |
Collapse
|
26
|
Shrivastav S, Kino T, Cunningham T, Ichijo T, Schubert U, Heinklein P, Chrousos GP, Kopp JB. Human immunodeficiency virus (HIV)-1 viral protein R suppresses transcriptional activity of peroxisome proliferator-activated receptor {gamma} and inhibits adipocyte differentiation: implications for HIV-associated lipodystrophy. Mol Endocrinol 2007; 22:234-47. [PMID: 17932108 DOI: 10.1210/me.2007-0124] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
HIV-1-infected patients may develop lipodystrophy and insulin resistance. We investigated the effect of the HIV-1 accessory protein viral protein R (Vpr) on the activity of the peroxisome proliferator-activating receptor-gamma (PPARgamma), a key regulator of adipocyte differentiation and tissue insulin sensitivity. We studied expression of PPARgamma-responsive reporter genes in 3T3-L1 mouse adipocytes. We investigated Vpr interaction with the PPAR/retinoid X receptor (RXR)-binding site of the c-Cbl-associating protein (CAP) gene using the chromatin immunoprecipitation assay as well as the interaction of Vpr and PPARgamma using coimmunoprecipitation. Finally, we studied the ability of exogenous Vpr protein to enter cultured adipocytes and retard differentiation. We found that Vpr suppressed PPARgamma-induced transactivation in both undifferentiated and differentiated 3T3-L1 cells. Transcriptional suppression by Vpr required an intact LXXLL coactivator motif. Vpr suppressed mRNA expression of PPARgamma-responsive genes in undifferentiated 3T3-L1 cells and associated with the PPAR/RXR-binding site located in the promoter region of the CAP gene. Vpr interacted with the ligand-binding domain of PPARgamma in an agonist-dependent fashion in vitro. Vpr delivered either by an expression plasmid or as protein added to media suppressed PPARgamma agonist-induced adipocyte differentiation, assessed as lipid accumulation and mRNA expression of the adipocyte differentiation marker adipocyte P2 in 3T3-L1 cells. In conclusion, circulating Vpr or, alternatively, Vpr produced as a consequence of direct infection of adipocytes could suppress in vivo differentiation of preadipocytes by acting as a corepressor of PPARgamma-mediated gene transcription. Vpr may alter sensitivity to insulin and thereby contribute to the development of lipodystrophy and insulin resistance observed in HIV-1-infected patients.
Collapse
Affiliation(s)
- Shashi Shrivastav
- Kidney Disease Section, National Institute of Diabetes and Digestive and Kidney Disease/NIH, 10 Center Drive MSC 1268, Bethesda, MD 20892-1268, USA
| | | | | | | | | | | | | | | |
Collapse
|
27
|
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.
Collapse
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,
| |
Collapse
|
28
|
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.
Collapse
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
Collapse
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
| | | | | |
Collapse
|
29
|
Muthumani K, Choo AY, Premkumar A, Hwang DS, Thieu KP, Desai BM, Weiner DB. Human immunodeficiency virus type 1 (HIV-1) Vpr-regulated cell death: insights into mechanism. Cell Death Differ 2006; 12 Suppl 1:962-70. [PMID: 15832179 DOI: 10.1038/sj.cdd.4401583] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The destruction of CD4(+) T cells and eventual induction of immunodeficiency is a hallmark of the human immunodeficiency virus type 1 infection (HIV-1). However, the mechanism of this destruction remains unresolved. Several auxiliary proteins have been proposed to play a role in this aspect of HIV pathogenesis including a 14 kDa protein named viral protein R (Vpr). Vpr has been implicated in the regulation of various cellular functions including apoptosis, cell cycle arrest, differentiation, and immune suppression. However, the mechanism(s) involved in Vpr-mediated apoptosis remains unresolved, and several proposed mechanisms for these effects are under investigation. In this review, we discuss the possibility that some of these proposed pathways might converge to modulate Vpr's behavior. Further, we also discuss caveats and future directions for investigation of the interesting biology of this HIV accessory gene.
Collapse
Affiliation(s)
- K Muthumani
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
| | | | | | | | | | | | | |
Collapse
|
30
|
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.
Collapse
Affiliation(s)
- Audrey Varin
- Department of Virology, EA3186, IFR133, Franche-Comté University, F-25030 Besançon, France
| | | | | | | | | | | | | | | | | |
Collapse
|
31
|
SILVERMAN MARNIN, PEARCE BRADD, BIRON CHRISTINEA, MILLER ANDREWH. Immune modulation of the hypothalamic-pituitary-adrenal (HPA) axis during viral infection. Viral Immunol 2005; 18:41-78. [PMID: 15802953 PMCID: PMC1224723 DOI: 10.1089/vim.2005.18.41] [Citation(s) in RCA: 325] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Compelling data has been amassed indicating that soluble factors, or cytokines, emanating from the immune system can have profound effects on the neuroendocrine system, in particular the hypothalamic- pituitary-adrenal (HPA) axis. HPA activation by cytokines (via the release of glucocorticoids), in turn, has been found to play a critical role in restraining and shaping immune responses. Thus, cytokine-HPA interactions represent a fundamental consideration regarding the maintenance of homeostasis and the development of disease during viral infection. Although reviews exist that focus on the bi-directional communication between the immune system and the HPA axis during viral infection (188,235), others have focused on the immunomodulatory effects of glucocorticoids during viral infection (14,225). This review, however, concentrates on the other side of the bi-directional loop of neuroendocrine-immune interactions, namely, the characterization of HPA axis activity during viral infection and the mechanisms employed by cytokines to stimulate glucocorticoid release.
Collapse
Affiliation(s)
- MARNI N. SILVERMAN
- Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, Georgia
| | - BRAD D. PEARCE
- Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, Georgia
| | - CHRISTINE A. BIRON
- Department of Molecular Microbiology and Immunology, Division of Biology and Medicine, Brown University, Providence, Rhode Island
| | - ANDREW H. MILLER
- Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, Georgia
- Address reprint requests to: Dr. Andrew H. Miller, Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, 101 Woodruff Circle, WMRB Suite 4000, Atlanta, Georgia 30322, E-mail:
| |
Collapse
|
32
|
Jin S, Chen C, Montelaro RC. Equine infectious anemia virus Gag p9 function in early steps of virus infection and provirus production. J Virol 2005; 79:8793-801. [PMID: 15994773 PMCID: PMC1168773 DOI: 10.1128/jvi.79.14.8793-8801.2005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2004] [Accepted: 03/18/2005] [Indexed: 01/14/2023] Open
Abstract
We have previously reported that serial truncation of the Gag p9 protein of equine infectious anemia virus (EIAV) revealed a progressive loss in replication phenotypes in transfected cells, such that a proviral mutant (E32) expressing the N-terminal 31 amino acids of p9 produced infectious virus particles similarly to parental provirus, while a proviral mutant (K30) with two fewer amino acids produced replication-defective virus particles, despite containing apparently normal levels of processed Gag and Pol proteins (C. Chen, F. Li, and R. C. Montelaro, J. Virol. 75:9762-9760, 2001). Based on these observations, we sought in the current study to identify the precise defect in K30 virion infection of permissive equine dermal (ED) cells. The results of these experiments clearly demonstrated that K30 virions entered target ED cells and produced early (minus-strand strong-stop) and late (Gag) viral DNA products as efficiently as did the replication-competent E32 mutant and parental EIAV(UK) viruses. However, in contrast to the replication-competent E32 mutant and parental viruses, infection with K30 mutant virus failed to produce detectable two-long-terminal-repeat DNA circles, stable integrated provirus, virus-specific Gag mRNA expression, or intracellular viral protein expression. Taken together, these data demonstrate that the K30 mutant is defective in the ability to produce sufficient nuclear viral DNA to establish a productive infection in ED cells. Thus, these observations indicate for the first time that the EIAV Gag p9 protein performs a critical role in viral DNA production and processing to provirus during EIAV infection, in addition to its previously defined role in viral budding mediated by the p9 L domain.
Collapse
Affiliation(s)
- Sha Jin
- Department of Molecular Genetics and Biochemistry, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | | | | |
Collapse
|
33
|
Tomkowicz B, Singh SP, Lai D, Singh A, Mahalingham S, Joseph J, Srivastava S, Srinivasan A. Mutational analysis reveals an essential role for the LXXLL motif in the transformation function of the human herpesvirus-8 oncoprotein, kaposin. DNA Cell Biol 2005; 24:10-20. [PMID: 15684715 DOI: 10.1089/dna.2005.24.10] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Human herpesvirus-8 (HHV-8) is causally linked to Kaposi's sarcoma (KS). Sequence analysis of the genome and subsequent studies revealed several genes including kaposin, with transformation properties in cell culture. In this study, we have analyzed the requirement of Kaposin A for cellular transformation in an effort to understand its contribution towards KS pathogenesis. Comparative analysis of Kaposin with other proteins identified the LXXLL motif spanning from residues 31-35 (LVCLL). The observation that the LXXLL motif is present in nuclear receptor coactivators that mediate the interaction of coactivators with nuclear receptors has prompted us to investigate the relevance of this motif for Kaposin's function(s). Kaposin A coding sequences were cloned into a eukaryotic expression plasmid with the Flag (FL) epitope fused in-frame at the C-terminus (Kap-FL). To evaluate the role of leucine residues in the motif, site-directed mutagenesis was utilized, whereby alanine was substituted for the leucine residues (Kap-AXXAA-FL). Both Kap-FL and Kap- AXXAA-FL exhibited similar levels of expression in cells. Interestingly, the Kap-AXXAA-FL mutant failed to show transforming activity by two independent assays: anchorage-independent growth, and focus formation. Immunofluorescence (IFA) and FACS analysis indicated that Kap-FL was localized around the nucleus and at the cell surface, respectively. However, Kap-AXXAA-FL exhibited diffuse cytoplasmic staining as measured by IFA yet was still detectable on the cell surface by FACS. Ironically, both Kap-FL and Kap-AXXAAFL were able to activate the AP-1 promoter. These results support an important role for the LXXLL motif in the ability of Kaposin to induce transformation.
Collapse
MESH Headings
- Amino Acid Motifs/genetics
- Amino Acid Sequence
- Animals
- Cell Nucleus/immunology
- Cell Transformation, Neoplastic/genetics
- Cell Transformation, Viral/genetics
- DNA Mutational Analysis
- Herpesvirus 8, Human/genetics
- Humans
- Leucine/genetics
- Mice
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Mutation/genetics
- NIH 3T3 Cells
- Oncogene Proteins, Viral/chemistry
- Oncogene Proteins, Viral/genetics
- Oncogene Proteins, Viral/metabolism
- Promoter Regions, Genetic/genetics
- Sarcoma, Kaposi/genetics
- Sarcoma, Kaposi/metabolism
- Sarcoma, Kaposi/virology
- Transcription Factor AP-1/genetics
- Transfection
- Viral Proteins/chemistry
- Viral Proteins/genetics
- Viral Proteins/metabolism
Collapse
Affiliation(s)
- Brian Tomkowicz
- Department of Microbiology and Immunology, Kimmel Cancer Institute, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
| | | | | | | | | | | | | | | |
Collapse
|
34
|
Le Rouzic E, Benichou S. The Vpr protein from HIV-1: distinct roles along the viral life cycle. Retrovirology 2005; 2:11. [PMID: 15725353 PMCID: PMC554975 DOI: 10.1186/1742-4690-2-11] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2005] [Accepted: 02/22/2005] [Indexed: 12/30/2022] Open
Abstract
The genomes of human and simian immunodeficiency viruses (HIV and SIV) encode the gag, pol and env genes and contain at least six supplementary open reading frames termed tat, rev, nef, vif, vpr, vpx and vpu. While the tat and rev genes encode regulatory proteins absolutely required for virus replication, nef, vif, vpr, vpx and vpu encode for small proteins referred to "auxiliary" (or "accessory"), since their expression is usually dispensable for virus growth in many in vitro systems. However, these auxiliary proteins are essential for viral replication and pathogenesis in vivo. The two vpr- and vpx-related genes are found only in members of the HIV-2/SIVsm/SIVmac group, whereas primate lentiviruses from other lineages (HIV-1, SIVcpz, SIVagm, SIVmnd and SIVsyk) contain a single vpr gene. In this review, we will mainly focus on vpr from HIV-1 and discuss the most recent developments in our understanding of Vpr functions and its role during the virus replication cycle.
Collapse
Affiliation(s)
- Erwann Le Rouzic
- Institut Cochin, Department of Infectious Diseases, INSERM U567, CNRS UMR8104, Université Paris 5, Paris, France
| | - Serge Benichou
- Institut Cochin, Department of Infectious Diseases, INSERM U567, CNRS UMR8104, Université Paris 5, Paris, France
| |
Collapse
|
35
|
Thotala D, Schafer EA, Tungaturthi PK, Majumder B, Janket ML, Wagner M, Srinivasan A, Watkins S, Ayyavoo V. Structure–functional analysis of human immunodeficiency virus type 1 (HIV-1) Vpr: role of leucine residues on Vpr-mediated transactivation and virus replication. Virology 2004; 328:89-100. [PMID: 15380361 DOI: 10.1016/j.virol.2004.07.013] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2004] [Accepted: 07/13/2004] [Indexed: 11/21/2022]
Abstract
HIV-1 Vpr has been shown to transactivate LTR-directed expression through its interaction with several proteins of cellular origin including the glucocorticoid receptor (GR). Upon activation, steroid receptors bind to proteins containing the signature motif LxxLL, translocate into the nucleus, bind to their response element, and activate transcription. The presence of such motifs in HIV-1 Vpr has prompted us to undertake the analysis of the role of specific leucine residue(s) involved in Vpr-GR interaction, subcellular localization and its effect on Vpr-GR-mediated transactivation. The individual leucine residues present in H I, II, and III were mutated in the Vpr molecule and evaluated for their ability to interact with GR, transactivate GRE and HIV-1 LTR promoters, and their colocalization with GR. While Vpr mutants L42 and L67 showed reduced activation, substitutions at L20, L23, L26, L39, L64, and L68 exhibited a similar and slightly higher level of activation compared to Vprwt. Interestingly, a substitution at residue L22 resulted in a significantly higher GRE and HIV-1 LTR transactivation (8- to 11-fold higher) in comparison to wild type. Confocal microscopy indicated that Vpr L22A exhibited a distinct condensed nuclear localization pattern different from the nuclear/perinuclear pattern noted with Vprwt. Further, electrophoretic mobility shift assay (EMSA) revealed that the VprL22A-GR complex had higher DNA-binding activity when compared to the wild type Vpr-GR complex. These results suggest a contrasting role for the leucine residues on HIV-1 LTR-directed transactivation dependent upon their location in Vpr.
Collapse
Affiliation(s)
- Dineshkumar Thotala
- Department of Infectious Diseases and Microbiology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
36
|
Tungaturthi PK, Sawaya BE, Ayyavoo V, Murali R, Srinivasan A. HIV-1 Vpr: Genetic Diversity and Functional Features from the Perspective of Structure. DNA Cell Biol 2004; 23:207-22. [PMID: 15142378 DOI: 10.1089/104454904773819798] [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] [Indexed: 11/13/2022] Open
Abstract
RNA viruses are well known for the enormous genetic variation. Retroviruses share this feature with other RNA viruses, and human immunodeficiency virus type 1 (HIV-1) has been extensively investigated in this regard. Based on the DNA sequence analysis, HIV-1 has been classified into three groups; M, N, and O, with viral subtypes in each group. While the genetic variation between viral isolates has been documented throughout the genome, specifically, the env gene exhibits high variation. Analysis of the env gene from the sequential samples from HIV-1-infected patients reveals variation in the range of 1% per year. The variation observed in individual HIV-1 genes in the form of changes at the nucleotide level, as expected, should result in one of the possible scenarios: (1) no change in the amino acid, (2) conservative change in the amino acid, (3) nonconservative change in the amino acid, and (4) premature stop codon resulting in a truncated protein. Hence, it is likely that the variation may impact on the function of the protein, depending on the nature of the mutation. The goal of this review is to summarize the polymorphisms in Vpr using the available sequence information and discuss their effects on the functions of Vpr from the point of view of its structure. The data generated by several groups provide a base for understanding the consequences of natural polymorphisms in specific regions of the Vpr molecule. However, it is also clear that secondary changes (second site or compensatory mutations) may modify the effect of a specific mutation and a comprehensive analysis is needed to delineate the role of specific residues in Vpr molecule. This is an area which, we hope, will attract investigators for further studies, and may provide information for understanding the molecular basis of Vpr functions.
Collapse
Affiliation(s)
- Parithosh K Tungaturthi
- Department of Microbiology and Immunology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
| | | | | | | | | |
Collapse
|
37
|
Muthumani K, Desai BM, Hwang DS, Choo AY, Laddy DJ, Thieu KP, Rao RG, Weiner DB. HIV-1 Vpr and Anti-Inflammatory Activity. DNA Cell Biol 2004; 23:239-47. [PMID: 15142381 DOI: 10.1089/104454904773819824] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
New and effective approaches for inflammatory diseases based on novel mechanisms of action are needed. One potential source of anti-inflammatory drugs exists among viruses. Viruses have evolved to infect, replicate within, and kill human cells through diverse mechanisms. They accomplish this fact by finding ways to out with the host's complex immune machinery. It is possible that the viral proteins and pathways involved in the downregulation of host immune function during infection can be exploited as a therapeutic in diseases that result in the overactivity of the immune system. Indeed, the human immunodeficiency virus type 1 (HIV-1) protein, Vpr, affects cells in a number of ways that may prove useful for exploitation for the treatment of inflammatory diseases. Vpr has effects on T-cell proliferation, cytokine production, chemokine production, and Nuclear Factor kappa B (NF-kappaB)-mediated transcription. Importantly, it has been observed that Vpr downregulates NF-kappaB and the production of pro-inflammatory cytokines such as TNF-alpha, and IL-12. These activities are worthy of further examination for control of hyperinflammatory and hyperproliferative conditions.
Collapse
Affiliation(s)
- Karuppiah Muthumani
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
| | | | | | | | | | | | | | | |
Collapse
|
38
|
Janket ML, Manickam P, Majumder B, Thotala D, Wagner M, Schafer EA, Collman RG, Srinivasan A, Ayyavoo V. Differential regulation of host cellular genes by HIV-1 viral protein R (Vpr): cDNA microarray analysis using isogenic virus. Biochem Biophys Res Commun 2004; 314:1126-32. [PMID: 14751250 DOI: 10.1016/j.bbrc.2004.01.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
HIV-1 Vpr is a protein with multiple functions. It has been suggested that such pleiotropic effects by a viral protein may be mediated by its association with viral and cellular proteins or through modulation of expression of specific cellular genes. To address this, we used cDNA microarray techniques to analyze the regulation of a panel of host cellular genes by HIV-1 Vpr using isogenic HIV-1 either with or without Vpr expression. Results indicate that Vpr downregulated the expression of genes involved in cell cycle/proliferation regulation, DNA repair, tumor antigens, and immune activation factors, and upregulated many ribosomal and structural proteins. These results for the first time reveal the involvement of several potential cellular genes, which may be useful, both for understanding Vpr functions and for the development of therapeutics targeting the Vpr molecule.
Collapse
Affiliation(s)
- Michelle L Janket
- Department of Infectious Diseases and Microbiology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
39
|
Rohr O, Marban C, Aunis D, Schaeffer E. Regulation of HIV-1 gene transcription: from lymphocytes to microglial cells. J Leukoc Biol 2003; 74:736-49. [PMID: 12960235 DOI: 10.1189/jlb.0403180] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Transcription is a crucial step for human immunodeficiency virus type 1 (HIV-1) expression in all infected host cells, from T lymphocytes, thymocytes, monocytes, macrophages, and dendritic cells in the immune system up to microglial cells in the central nervous system. To maximize its replication, HIV-1 adapts transcription of its integrated proviral genome by ideally exploiting the specific cellular environment and by forcing cellular stimulatory events and impairing transcriptional inhibition. Multiple cell type-specific interplays between cellular and viral factors perform the challenge for the virus to leave latency and actively replicate in a great diversity of cells, despite the variability of its long terminal repeat region in different HIV strains. Knowledge about the molecular mechanisms underlying transcriptional regulatory events helps in the search for therapeutic agents that target the step of transcription in anti-HIV strategies.
Collapse
Affiliation(s)
- Olivier Rohr
- Institut National de la Santé Recherche Médicale Unité, Strasbourg, France
| | | | | | | |
Collapse
|
40
|
Bruns K, Fossen T, Wray V, Henklein P, Tessmer U, Schubert U. Structural characterization of the HIV-1 Vpr N terminus: evidence of cis/trans-proline isomerism. J Biol Chem 2003; 278:43188-201. [PMID: 12881523 DOI: 10.1074/jbc.m305413200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The 96-residue human immunodeficiency virus (HIV) accessory protein Vpr serves manifold functions in the retroviral life cycle including augmentation of viral replication in non-dividing host cells, induction of G2 cell cycle arrest, and modulation of HIV-induced apoptosis. Using a combination of dynamic light scattering, circular dichroism, and NMR spectroscopy the N terminus of Vpr is shown to be a unique domain of the molecule that behaves differently from the C-terminal domain in terms of self-association and secondary structure folding. Interestingly, the four highly conserved proline residues in the N terminus are predicted to have a high propensity for cis/trans isomerism. Thus the high resolution structure and folding of a synthetic N-terminal peptide (Vpr1-40) and smaller fragments thereof have been investigated. 1H NMR data indicate Vpr1-40 possesses helical structure between residues 17-32, and for the first time, this helix, which is bound by proline residues, was observed even in aqueous solution devoid of any detergent supplements. In addition, NMR data revealed that all of the proline residues undergo a cis/ trans isomerism to such an extent that approximately 40% of all Vpr molecules possess at least one proline in a cis conformation. This phenomenon of cis/trans isomerism, which is unprecedented for HIV-1 Vpr, not only provides an explanation for the molecular heterogeneity observed in the full-length molecule but also indicates that in vivo the folding and function of Vpr should depend on a cis/trans-proline isomerase activity, particularly as two of the proline residues in positions 14 and 35 show considerable amounts of cis isomers. This prediction correlates well with our recent observation (Zander, K., Sherman, M. P., Tessmer, U., Bruns, K., Wray, V., Prechtel, A. T., Schubert, E., Henklein, P., Luban, J., Neidleman, J., Greene, W. C., and Schubert, U. (2003) J. Biol. Chem. 278, 43170-43181) of a functional interaction between the major cellular isomerase cyclophilin A and Vpr, both of which are incorporated into HIV-1 virions.
Collapse
Affiliation(s)
- Karsten Bruns
- Department of Structural Biology, Gesellschaft für Biotechnologische Forschung, D-38124 Braunschweig, Germany.
| | | | | | | | | | | |
Collapse
|
41
|
Zander K, Sherman MP, Tessmer U, Bruns K, Wray V, Prechtel AT, Schubert E, Henklein P, Luban J, Neidleman J, Greene WC, Schubert U. Cyclophilin A interacts with HIV-1 Vpr and is required for its functional expression. J Biol Chem 2003; 278:43202-13. [PMID: 12881522 DOI: 10.1074/jbc.m305414200] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Viral protein R (Vpr) of human immunodeficiency virus, type 1 (HIV-1) is the major virion-associated accessory protein that affects a number of biological functions in the retroviral life cycle, including promotion of the transport of the preintegration complex into the nucleus and the induction of G2 host cell cycle arrest. Our recent investigation of the conformational heterogeneity of the proline residues in the N terminus of Vpr suggested a functional interaction between Vpr and a host peptidylprolyl cis/trans isomerase (PPIase) that might regulate the cis/trans interconversion of the imidic bond within the conserved proline residues of Vpr in vivo. Using surface plasmon resonance spectroscopy, Far Western blot, and pulldown experiments a physical interaction of Vpr with the major host PPIase cyclophilin A (CypA) is now demonstrated. The interaction domain involves the N-terminal region of Vpr including an essential role for proline in position 35. The CypA inhibitor cyclosporin A and non-immunosuppressive PPIase inhibitors such as NIM811 and sanglifehrin A block expression of Vpr without affecting pre- or post-translational events such as transcription, intracellular transport, or virus incorporation of Vpr. Similarly to CypA inhibition, Vpr expression is also reduced in HIV-1 infected CypA-/- knock-out T cells. This study thus shows that in addition to the interaction between CypA and HIV-1 capsid occurring during early steps in virus replication, CypA is also important for the de novo synthesis of Vpr and that in the absence of CypA activity, the Vpr-mediated cell cycle arrest is completely lost in HIV-1-infected T cells.
Collapse
Affiliation(s)
- Kerstin Zander
- Heinrich-Pette-Institute of Experimental Virology and Immunology, University of Hamburg, D-20251 Hamburg, Germany
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
42
|
Sherman MP, de Noronha CMC, Eckstein LA, Hataye J, Mundt P, Williams SAF, Neidleman JA, Goldsmith MA, Greene WC. Nuclear export of Vpr is required for efficient replication of human immunodeficiency virus type 1 in tissue macrophages. J Virol 2003; 77:7582-9. [PMID: 12805458 PMCID: PMC164827 DOI: 10.1128/jvi.77.13.7582-7589.2003] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Retroviruses must gain access to the host cell nucleus for subsequent replication and viral propagation. Human immunodeficiency virus type 1 (HIV-1) and other primate lentiviruses are distinguished from the gammaretroviruses by their ability to infect nondividing cells such as macrophages, an important viral reservoir in vivo. Rather than requiring nuclear membrane breakdown during cell division, the HIV-1 preintegration complex (PIC) enters the nucleus by traversing the central aqueous channel of the limiting nuclear pore complex. The HIV-1 PIC contains three nucleophilic proteins, matrix, integrase, and Vpr, all of which have been implicated in nuclear targeting. The mechanism by which Vpr can display such nucleophilic properties and yet also be available for incorporation into virions assembling at the plasma membrane is unresolved. We recently characterized Vpr as a nucleocytoplasmic shuttling protein that contains two novel nuclear import signals and an exportin-1-dependent nuclear export signal (NES). We now demonstrate that mutation of this NES impairs the incorporation of Vpr into newly formed virions. Furthermore, we find that the Vpr NES is required for efficient HIV replication in tissue macrophages present in human spleens and tonsils. These findings underscore how the nucleocytoplasmic shuttling of Vpr not only contributes to nuclear import of the HIV-1 PIC but also enables Vpr to be present in the cytoplasm for incorporation into virions, leading to enhancement of viral spread within nondividing tissue macrophages.
Collapse
Affiliation(s)
- Michael P Sherman
- Gladstone Institute of Virology and Immunology, San Francisco, California 94141, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
43
|
Lahti AL, Manninen A, Saksela K. Regulation of T cell activation by HIV-1 accessory proteins: Vpr acts via distinct mechanisms to cooperate with Nef in NFAT-directed gene expression and to promote transactivation by CREB. Virology 2003; 310:190-6. [PMID: 12788643 DOI: 10.1016/s0042-6822(03)00164-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Nef and Vpr are lentiviral accessory proteins that have been implicated in regulation of cellular gene expression. We noticed that Vpr can potentiate Nef-induced activation of nuclear factor of activated T cells (NFAT)-dependent transcription. Unlike Nef, which stimulated calcium signaling to activate NFAT, Vpr functioned farther downstream. Similar to the positive effects of Vpr on most of the transcriptional test systems that we used, potentiation of NFAT-directed gene expression was relatively modest in magnitude (two- to threefold) and depended on the cell cycle-arresting capacity of Vpr. By contrast, we found that Vpr could cause more than fivefold upregulation of cyclic AMP response element (CRE)-directed transcription via a mechanism that did not require Vpr-induced G2/M arrest. This effect, however, was only evident under suboptimal conditions known to lead to serine phosphorylation of the CRE binding factor (CREB) but not to CREB-dependent gene expression. This suggested that Vpr may act by stabilizing interactions with CREB and its transcriptional cofactor CREB binding protein (CBP). Indeed, this effect could be blocked by cotransfection of the adenoviral CBP inhibitor E1A. These results provide additional evidence for cell cycle-independent regulation of gene expression by Vpr and implicate CREB as a potentially important target for Vpr action in HIV-infected host cells.
Collapse
Affiliation(s)
- Anna L Lahti
- Institute of Medical Technology, FIN-33014 University of Tampere, Tampere, Finland
| | | | | |
Collapse
|
44
|
Bruland T, Lavik LAS, Dai HY, Dalen A. A glucocorticoid response element in the LTR U3 region of Friend murine leukaemia virus variant FIS-2 enhances virus production in vitro and is a major determinant for sex differences in susceptibility to FIS-2 infection in vivo. J Gen Virol 2003; 84:907-916. [PMID: 12655091 DOI: 10.1099/vir.0.18625-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The nucleotide sequence of the Friend murine leukaemia virus variant FIS-2 LTR has high identity with the closely related Friend murine leukaemia virus (F-MuLV) LTR, except for the deletion of one direct repeat, a few point mutations and the generation of a glucocorticoid response element (GRE) in the U3 region. The GRE can mediate gene induction by glucocorticoids, mineral corticoids, progesterone and androgens, and it has been shown that incorporation of a GRE(s) within the LTR can increase the transcriptional activity of retroviral enhancers. We have previously reported an increased early virus replication in male mice compared with female mice when infected with a virus containing the FIS-2 LTR and have proposed that the GRE might contribute to this sex difference. In the present study, we introduced a single point mutation in the GRE and performed comparative studies in NIH 3T3 cells and in young adult male and female NMRI mice. We found that significantly more virus was produced from NIH 3T3 cells infected with wt FIS-2 than from cells infected with the FIS-2 GRE mutant and that this difference was further augmented by glucocorticoids. The glucocorticoid antagonist RU486 inhibited virus production in a dose-dependent manner. The wt FIS-2 disseminated significantly faster than the FIS-2 GRE mutant in both male and female mice. There was no significant difference in the dissemination rate between male and female mice infected with the FIS-2 GRE mutant. Hence, the GRE in the FIS-2 LTR is one determinant of the significant sex difference in susceptibility to FIS-2 infection.
Collapse
Affiliation(s)
- Torunn Bruland
- Department of Laboratory Medicine, Children's and Women's Health, Faculty of Medicine, Norwegian University of Science and Technology, MTFS Olav Kyrresg. 3, N-7489 Trondheim, Norway
| | | | | | - Are Dalen
- St Olavs Hospital HF, Trondheim, Norway
- Department of Laboratory Medicine, Children's and Women's Health, Faculty of Medicine, Norwegian University of Science and Technology, MTFS Olav Kyrresg. 3, N-7489 Trondheim, Norway
| |
Collapse
|
45
|
Abstract
The human immunodeficiency virus type 1 (HIV-1) genome encodes a highly conserved regulatory gene product, Vpr (96 residues, 14kDa), which is incorporated into virions. In the infected cells, Vpr, expressed late in the virus cycle, is believed to function in the early phases of HIV-1 replication, such as nuclear migration of pre-integration complex, transcription of the proviral genome, viral multiplication by blocking cells in G2 phase and regulation of apoptosis phenomenon. Vpr has a critical role in long term AIDS disease by inducing infection in non-dividing cells such as monocytes and macrophages. To gain insight into the structure-function relationships of Vpr, the (1-96)Vpr protein was synthesized with 22 labeled amino acids. Its 3D structure was analyzed in the presence of CD(3)CN and in pure water at low pH and refined by restrained simulated annealing. The structure of the protein is characterized by three well-defined alpha-helices: 17-33, 38-50 and 56-77 surrounded by flexible N and C-terminal domains. In contrast to the structure obtained in the presence of TFE, the three alpha-helices are folded around a hydrophobic core constituted of Leu, Ile, Val and aromatic residues as illustrated by numerous long range NOEs. This structure accounts for the interaction of Vpr with different targets.
Collapse
Affiliation(s)
- N Morellet
- Département de Pharmacochimie Moléculaire et Structurale, INSERM U266-CNRS FRE 2463, UFR des Sciences Pharmaceutiques et Biologiques, 4 Avenue de l'Observatoire, 75270 Paris Cedex 06, France.
| | | | | | | |
Collapse
|
46
|
Mirani M, Elenkov I, Volpi S, Hiroi N, Chrousos GP, Kino T. HIV-1 protein Vpr suppresses IL-12 production from human monocytes by enhancing glucocorticoid action: potential implications of Vpr coactivator activity for the innate and cellular immunity deficits observed in HIV-1 infection. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 169:6361-8. [PMID: 12444143 DOI: 10.4049/jimmunol.169.11.6361] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The HIV-1 protein Vpr has glucocorticoid receptor coactivator activity, potently increasing the sensitivity of glucocorticoid target tissues to cortisol. Patients with AIDS and normal cortisol secretion have manifestations compatible with glucocorticoid hypersensitivity of the immune system, such as suppression of innate and cellular immunities. The latter can be explained by glucocorticoid-induced inhibition of cytokine networks regulating innate and Th1-driven cellular immunity. We demonstrated that extracellularly administered Vpr protein dose-dependently potentiated glucocorticoid-induced suppression of both mRNA expression and secretion of IL-12 subunit p35 and IL-12 holo-protein, but not IL-12 subunit p40 or IL-10, by human monocytes/macrophages stimulated with LPS or heat-killed, formalin-fixed Staphylococcus aureus (Cowan strain 1). This effect was inhibited by the glucocorticoid receptor antagonist RU 486. Also, Vpr changed the expression of an additional five glucocorticoid-responsive genes in the same direction as dexamethasone and was active in potentiating the trans-activation, but not the trans-repression, properties of the glucocorticoid receptor on nuclear factor kappaB- or activating protein 1-regulated simple promoters. Thus, extracellular Vpr enhances the suppressive actions of the ligand-activated glucocorticoid receptor on IL-12 secretion by human monocytes/macrophages. Through this effect, Vpr may contribute to the suppression of innate and cellular immunities of HIV-1-infected individuals and AIDS patients.
Collapse
Affiliation(s)
- Marco Mirani
- Pediatric and Reproductive Endocrinology Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | | | | | | | | | | |
Collapse
|
47
|
Sherman MP, Schubert U, Williams SA, de Noronha CMC, Kreisberg JF, Henklein P, Greene WC. HIV-1 Vpr displays natural protein-transducing properties: implications for viral pathogenesis. Virology 2002; 302:95-105. [PMID: 12429519 DOI: 10.1006/viro.2002.1576] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The 14-kDa Vpr protein of human immunodeficiency virus type 1 (HIV-1) serves multiple functions in the retroviral life cycle, including the enhancement of viral replication in nondividing macrophages, the induction of G2 cell-cycle arrest in proliferating T lymphocytes, and the modulation of HIV-1-induced apoptosis. Extracellular Vpr has been detected in the sera and cerebral spinal fluid of HIV-infected patients. However, it is not known whether such forms of Vpr are biologically active. Vpr contains a carboxy-terminal basic amino acid rich segment stretch that is homologous to domains that mediate the energy- and receptor-independent cellular uptake of polypeptides by a process termed protein transduction. Similar functional protein-transducing domains are present in HIV-1 Tat, herpes simplex virus-1 DNA-binding protein VP22, and the Drosophila antennapedia homeotic transcription factor. We now demonstrate effective transduction of biologically active, synthetic Vpr (sVpr) as well as the Vpr-beta-galactosidase fusion protein. However, in contrast to other transducing proteins, Vpr transduction is not enhanced by protein denaturation, and Vpr's carboxy-terminal basic domain alone is not sufficient for its transduction across biological membranes. In contrast, the full-length Vpr protein effectively transduces a broad array of cells, leading to dose-dependent G2 cell-cycle arrest and apoptosis. Addition of Vpr into the extracellular medium also rescues the replication of Vpr-deficient strains of HIV-1 in human macrophage cultures. Native Vpr may thus be optimized for protein transduction, a feature that might enhance and extend the pathological effects of HIV infection.
Collapse
Affiliation(s)
- Michael P Sherman
- Gladstone Institute of Virology and Immunology, San Fransisco, California 94141, USA
| | | | | | | | | | | | | |
Collapse
|
48
|
Kino T, Gragerov A, Slobodskaya O, Tsopanomichalou M, Chrousos GP, Pavlakis GN. Human immunodeficiency virus type 1 (HIV-1) accessory protein Vpr induces transcription of the HIV-1 and glucocorticoid-responsive promoters by binding directly to p300/CBP coactivators. J Virol 2002; 76:9724-34. [PMID: 12208951 PMCID: PMC136530 DOI: 10.1128/jvi.76.19.9724-9734.2002] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The accessory Vpr protein of human immunodeficiency virus type 1 (HIV-1) is a promiscuous activator of viral and cellular promoters. We report that Vpr enhances expression of the glucocorticoid receptor-induced mouse mammary tumor virus (MMTV) promoter and of the Tat-induced HIV-1 long terminal repeat promoter by directly binding to p300/CBP coactivators. In contrast, Vpr does not bind to p/CAF or to members of the p160 family of nuclear receptor coactivators, such as steroid receptor coactivator 1a and glucocorticoid receptor (GR)-interacting protein 1. Vpr forms a stable complex with p300 and also interacts with the ligand-bound glucocorticoid receptor in vivo. Mutation analysis showed that the C-terminal part of Vpr binds to the C-terminal portion of p300/CBP within amino acids 2045 to 2191. The same p300 region interacts with the p160 coactivators and with the adenovirus E1A protein. Accordingly, E1A competed for binding to p300 in vitro. Coexpression of E1A or of small fragments of p300 containing the Vpr binding site resulted in inhibition of Vpr's transcriptional effects. The C-terminal part of p300 containing the transactivating region is required for Vpr transactivation, whereas the histone acetyltransferase enzymatic region is dispensable. Vpr mutants that bind p300 but not the GR did not activate expression of the MMTV promoter and had dominant-negative effects. These results indicate that Vpr activates transcription by acting as an adapter linking transcription components and coactivators.
Collapse
Affiliation(s)
- Tomoshige Kino
- Pediatric and Reproductive Endocrinology Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-1583, USA.
| | | | | | | | | | | |
Collapse
|
49
|
Sherman MP, De Noronha CMC, Williams SA, Greene WC. Insights into the biology of HIV-1 viral protein R. DNA Cell Biol 2002; 21:679-88. [PMID: 12396611 DOI: 10.1089/104454902760330228] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
HIV-1 viral protein R (Vpr) is a small, highly conserved accessory protein encoded by the HIV genome that serves many functions in the viral life cycle. Vpr induces G2 cell cycle arrest, which is thought to indirectly enhance viral replication by increasing transcription from the LTR. Vpr has also been implicated in facilitating infection of nondividing cells, most notably macrophages. Because Vpr is a nucleo-cytoplasmic shuttling protein, its role in enhancing viral replication in macrophages may be mediated through enhanced entry of the HIV preintegration complex through the limiting nuclear pore. Free Vpr is detectable in the serum of patients, and in vitro studies implicate extracellular forms of Vpr as an effector of cellular responses mediated through its ability to transduce through intact cytoplasmic membranes. We review the biologic properties of Vpr, focusing on its mechanism of action, role in HIV replication, and significance for host pathogenesis.
Collapse
Affiliation(s)
- Michael P Sherman
- Gladstone Institute of Virology and Immunology and Department of Medicine, University of California, San Francisco, California 94141-9100, USA
| | | | | | | |
Collapse
|
50
|
Muthumani K, Hwang DS, Dayes NS, Kim JJ, Weiner DB. The HIV-1 accessory gene vpr can inhibit antigen-specific immune function. DNA Cell Biol 2002; 21:689-95. [PMID: 12396612 DOI: 10.1089/104454902760330237] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The 14-kDa HIV-1 accessory gene vpr has been reported to have effects on host cell biology. These activities include inhibition of cell proliferation, inhibition of NF-kappaB activation, inhibition of CD4 T-cell proliferation, and induction of apoptosis in tissue culture. This collection of activities could, in theory, impact host cell immune responses. We tested the activity of recombinant Vpr protein to inhibit T-cell activation in vitro. Here, we present data illustrating that the Vpr protein can significantly suppress T-cell activation-related cytokine elaboration and proliferation. In vivo, we observed that covaccination with plasmids expressing the vpr gene product profoundly reduces antigen-specific CD8-mediated cytotoxic T lymphocyte (CTL) activity. This supports that vpr might compromise T-cell immunity in vivo during infection. To study this aspect of Vpr biology, we developed an Adenoviral Vpr expression vector for delivery of Vpr to immune cells and to study Vpr function in the absence of other lentiviral gene products. This vector delivers a functional Vpr protein to immune cells including antigen-presenting cells (APCs). We observe that the Adeno-Vpr vector suppresses human CD4 T-cell proliferation driven by immune activation in vitro. Further study of the biology of Vpr will likely have importance for a clearer understanding of host pathogenesis as well as have important implications for HIV vaccine development.
Collapse
|