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Acs-Szabo L, Papp LA, Miklos I. Understanding the molecular mechanisms of human diseases: the benefits of fission yeasts. MICROBIAL CELL (GRAZ, AUSTRIA) 2024; 11:288-311. [PMID: 39104724 PMCID: PMC11299203 DOI: 10.15698/mic2024.08.833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Revised: 07/04/2024] [Accepted: 07/10/2024] [Indexed: 08/07/2024]
Abstract
The role of model organisms such as yeasts in life science research is crucial. Although the baker's yeast (Saccharomyces cerevisiae) is the most popular model among yeasts, the contribution of the fission yeasts (Schizosaccharomyces) to life science is also indisputable. Since both types of yeasts share several thousands of common orthologous genes with humans, they provide a simple research platform to investigate many fundamental molecular mechanisms and functions, thereby contributing to the understanding of the background of human diseases. In this review, we would like to highlight the many advantages of fission yeasts over budding yeasts. The usefulness of fission yeasts in virus research is shown as an example, presenting the most important research results related to the Human Immunodeficiency Virus Type 1 (HIV-1) Vpr protein. Besides, the potential role of fission yeasts in the study of prion biology is also discussed. Furthermore, we are keen to promote the uprising model yeast Schizosaccharomyces japonicus, which is a dimorphic species in the fission yeast genus. We propose the hyphal growth of S. japonicus as an unusual opportunity as a model to study the invadopodia of human cancer cells since the two seemingly different cell types can be compared along fundamental features. Here we also collect the latest laboratory protocols and bioinformatics tools for the fission yeasts to highlight the many possibilities available to the research community. In addition, we present several limiting factors that everyone should be aware of when working with yeast models.
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Affiliation(s)
- Lajos Acs-Szabo
- Department of Genetics and Applied Microbiology, Faculty of Science and Technology, University of DebrecenDebrecen, 4032Hungary
| | - Laszlo Attila Papp
- Department of Genetics and Applied Microbiology, Faculty of Science and Technology, University of DebrecenDebrecen, 4032Hungary
| | - Ida Miklos
- Department of Genetics and Applied Microbiology, Faculty of Science and Technology, University of DebrecenDebrecen, 4032Hungary
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Vanegas-Torres CA, Schindler M. HIV-1 Vpr Functions in Primary CD4 + T Cells. Viruses 2024; 16:420. [PMID: 38543785 PMCID: PMC10975730 DOI: 10.3390/v16030420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Revised: 03/05/2024] [Accepted: 03/05/2024] [Indexed: 05/23/2024] Open
Abstract
HIV-1 encodes four accesory proteins in addition to its structural and regulatory genes. Uniquely amongst them, Vpr is abundantly present within virions, meaning it is poised to exert various biological effects on the host cell upon delivery. In this way, Vpr contributes towards the establishment of a successful infection, as evidenced by the extent to which HIV-1 depends on this factor to achieve full pathogenicity in vivo. Although HIV infects various cell types in the host organism, CD4+ T cells are preferentially targeted since they are highly permissive towards productive infection, concomitantly bringing about the hallmark immune dysfunction that accompanies HIV-1 spread. The last several decades have seen unprecedented progress in unraveling the activities Vpr possesses in the host cell at the molecular scale, increasingly underscoring the importance of this viral component. Nevertheless, it remains controversial whether some of these advances bear in vivo relevance, since commonly employed cellular models significantly differ from primary T lymphocytes. One prominent example is the "established" ability of Vpr to induce G2 cell cycle arrest, with enigmatic physiological relevance in infected primary T lymphocytes. The objective of this review is to present these discoveries in their biological context to illustrate the mechanisms whereby Vpr supports HIV-1 infection in CD4+ T cells, whilst identifying findings that require validation in physiologically relevant models.
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Affiliation(s)
| | - Michael Schindler
- Institute for Medical Virology and Epidemiology of Viral Diseases, University Hospital Tuebingen, 72076 Tuebingen, Germany;
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Zhao RY. Yeast for virus research. MICROBIAL CELL (GRAZ, AUSTRIA) 2017; 4:311-330. [PMID: 29082230 PMCID: PMC5657823 DOI: 10.15698/mic2017.10.592] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 08/27/2017] [Indexed: 12/25/2022]
Abstract
Budding yeast (Saccharomyces cerevisiae) and fission yeast (Schizosaccharomyces pombe) are two popular model organisms for virus research. They are natural hosts for viruses as they carry their own indigenous viruses. Both yeasts have been used for studies of plant, animal and human viruses. Many positive sense (+) RNA viruses and some DNA viruses replicate with various levels in yeasts, thus allowing study of those viral activities during viral life cycle. Yeasts are single cell eukaryotic organisms. Hence, many of the fundamental cellular functions such as cell cycle regulation or programed cell death are highly conserved from yeasts to higher eukaryotes. Therefore, they are particularly suited to study the impact of those viral activities on related cellular activities during virus-host interactions. Yeasts present many unique advantages in virus research over high eukaryotes. Yeast cells are easy to maintain in the laboratory with relative short doubling time. They are non-biohazardous, genetically amendable with small genomes that permit genome-wide analysis of virologic and cellular functions. In this review, similarities and differences of these two yeasts are described. Studies of virologic activities such as viral translation, viral replication and genome-wide study of virus-cell interactions in yeasts are highlighted. Impacts of viral proteins on basic cellular functions such as cell cycle regulation and programed cell death are discussed. Potential applications of using yeasts as hosts to carry out functional analysis of small viral genome and to develop high throughput drug screening platform for the discovery of antiviral drugs are presented.
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Affiliation(s)
- Richard Yuqi Zhao
- Department of Pathology, Department of Microbiology and Immunology, Institute of Global Health, and Institute of Human Virology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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Gonzalez G, DaFonseca S, Errazuriz E, Coric P, Souquet F, Turcaud S, Boulanger P, Bouaziz S, Hong SS. Characterization of a novel type of HIV-1 particle assembly inhibitor using a quantitative luciferase-Vpr packaging-based assay. PLoS One 2011; 6:e27234. [PMID: 22073298 PMCID: PMC3207847 DOI: 10.1371/journal.pone.0027234] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Accepted: 10/12/2011] [Indexed: 12/02/2022] Open
Abstract
The HIV-1 auxiliary protein Vpr and Vpr-fusion proteins can be copackaged with Gag precursor (Pr55Gag) into virions or membrane-enveloped virus-like particles (VLP). Taking advantage of this property, we developed a simple and sensitive method to evaluate potential inhibitors of HIV-1 assembly in a living cell system. Two proteins were coexpressed in recombinant baculovirus-infected Sf9 cells, Pr55Gag, which formed the VLP backbone, and luciferase fused to the N-terminus of Vpr (LucVpr). VLP-encapsidated LucVpr retained the enzymatic activity of free luciferase. The levels of luciferase activity present in the pelletable fraction recovered from the culture medium correlated with the amounts of extracellular VLP released by Sf9 cells assayed by conventional immunological methods. Our luciferase-based assay was then applied to the characterization of betulinic acid (BA) derivatives that differed from the leader compound PA-457 (or DSB) by their substituant on carbon-28. The beta-alanine-conjugated and lysine-conjugated DSB could not be evaluated for their antiviral potentials due to their high cytotoxicity, whereas two other compounds with a lesser cytotoxicity, glycine-conjugated and ε-NH-Boc-lysine-conjugated DSB, exerted a dose-dependent negative effect on VLP assembly and budding. A fifth compound with a low cytotoxicity, EP-39 (ethylene diamine-conjugated DSB), showed a novel type of antiviral effect. EP-39 provoked an aberrant assembly of VLP, resulting in nonenveloped, morula-like particles of 100-nm in diameter. Each morula was composed of nanoparticle subunits of 20-nm in diameter, which possibly mimicked transient intermediates of the HIV-1 Gag assembly process. Chemical cross-linking in situ suggested that EP-39 favored the formation or/and persistence of Pr55Gag trimers over other oligomeric species. EP-39 showed a novel type of negative effect on HIV-1 assembly, targeting the Pr55Gag oligomerisation. The biological effect of EP-39 underlined the critical role of the nature of the side chain at position 28 of BA derivatives in their anti-HIV-1 activity.
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Affiliation(s)
- Gaëlle Gonzalez
- Université Lyon I & INRA UMR-754, Retrovirus & Comparative Pathology, Lyon, France
| | - Sandrina DaFonseca
- Université Lyon I & INRA UMR-754, Retrovirus & Comparative Pathology, Lyon, France
| | - Elisabeth Errazuriz
- Centre Commun d'Imagerie Laënnec, Université Lyon I, Faculté de Medicine, Lyon, France
| | - Pascale Coric
- Laboratoire de Cristallographie et RMN Biologiques, CNRS UMR-8015, UFR des Sciences Pharmaceutiques et Biologiques, Université Paris Descartes, Paris, France
| | - Florence Souquet
- Laboratoire Synthèse et Structure de Molécules d'Intérêt Pharmacologique, CNRS UMR-8638, UFR des Sciences Pharmaceutiques et Biologiques, Université Paris Descartes, Paris, France
| | - Serge Turcaud
- Laboratoire Synthèse et Structure de Molécules d'Intérêt Pharmacologique, CNRS UMR-8638, UFR des Sciences Pharmaceutiques et Biologiques, Université Paris Descartes, Paris, France
| | - Pierre Boulanger
- Université Lyon I & INRA UMR-754, Retrovirus & Comparative Pathology, Lyon, France
| | - Serge Bouaziz
- Laboratoire de Cristallographie et RMN Biologiques, CNRS UMR-8015, UFR des Sciences Pharmaceutiques et Biologiques, Université Paris Descartes, Paris, France
| | - Saw See Hong
- Université Lyon I & INRA UMR-754, Retrovirus & Comparative Pathology, Lyon, France
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Dafonseca S, Coric P, Gay B, Hong SS, Bouaziz S, Boulanger P. The inhibition of assembly of HIV-1 virus-like particles by 3-O-(3',3'-dimethylsuccinyl) betulinic acid (DSB) is counteracted by Vif and requires its Zinc-binding domain. Virol J 2008; 5:162. [PMID: 19105849 PMCID: PMC2628355 DOI: 10.1186/1743-422x-5-162] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2008] [Accepted: 12/23/2008] [Indexed: 01/02/2023] Open
Abstract
Background DSB, the 3-O-(3',3'dimethylsuccinyl) derivative of betulinic acid, blocks the last step of protease-mediated processing of HIV-1 Gag precursor (Pr55Gag), which leads to immature, noninfectious virions. When administered to Pr55Gag-expressing insect cells (Sf9), DSB inhibits the assembly and budding of membrane-enveloped virus-like particles (VLP). In order to explore the possibility that viral factors could modulate the susceptibility to DSB of the VLP assembly process, several viral proteins were coexpressed individually with Pr55Gag in DSB-treated cells, and VLP yields assayed in the extracellular medium. Results Wild-type Vif (Vifwt) restored the VLP production in DSB-treated cells to levels observed in control, untreated cells. DSB-counteracting effect was also observed with Vif mutants defective in encapsidation into VLP, suggesting that packaging and anti-DSB effect were separate functions in Vif. The anti-DSB effect was abolished for VifC133S and VifS116V, two mutants which lacked the zinc binding domain (ZBD) formed by the four H108C114C133H139 coordinates with a Zn atom. Electron microscopic analysis of cells coexpressing Pr55Gag and Vifwt showed that a large proportion of VLP budded into cytoplasmic vesicles and were released from Sf9 cells by exocytosis. However, in the presence of mutant VifC133S or VifS116V, most of the VLP assembled and budded at the plasma membrane, as in control cells expressing Pr55Gag alone. Conclusion The function of HIV-1 Vif protein which negated the DSB inhibition of VLP assembly was independent of its packaging capability, but depended on the integrity of ZBD. In the presence of Vifwt, but not with ZBD mutants VifC133S and VifS116V, VLP were redirected to a vesicular compartment and egressed via the exocytic pathway.
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Affiliation(s)
- Sandrina Dafonseca
- Université de Lyon I-Claude Bernard, Faculté de Médecine Laënnec, Laboratoire de Virologie & Pathologie Humaine, CNRS FRE-3011, 69372 Lyon Cedex 08, France.
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Human immunodeficiency virus type 1 Vpr binds to the N lobe of the Wee1 kinase domain and enhances kinase activity for CDC2. J Virol 2008; 82:5672-82. [PMID: 18385244 DOI: 10.1128/jvi.01330-07] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human immunodeficiency virus type 1 Vpr is a virion-associated accessory protein that has multiple activities within an infected cell. One of the most dramatic effects of Vpr is the induction of cell cycle arrest at the G(2)/M boundary, followed by apoptosis. This effect has implications for CD4(+) cell loss in AIDS. In normal cell cycle regulation, Wee1, a key regulator for G(2)-M progression, phosphorylates Tyr15 on Cdc2 and thereby blocks the progression of cells into M phase. We demonstrate that Vpr physically interacts with Wee1 at the N lobe of the kinase domain analogous to that present in other kinases. This interaction with Vpr enhances Wee1 kinase activity for Cdc2. Overexpression of Wee1 kinase-deficient mutants competes for Vpr-mediated cell cycle arrest, and deletion of the region of Wee1 that binds Vpr abrogates that competition. However, the Vpr mutants I74P and I81P, which fail to induce G(2) arrest, can bind to and increase the kinase activity of Wee1 to the same extent as wild-type Vpr. Therefore, we conclude that the binding of Vpr to Wee1 is not sufficient for Vpr to activate the G(2) checkpoint, and it may reflect an independent function of Vpr.
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Benko Z, Liang D, Agbottah E, Hou J, Taricani L, Young PG, Bukrinsky M, Zhao RY. Antagonistic interaction of HIV-1 Vpr with Hsf-mediated cellular heat shock response and Hsp16 in fission yeast (Schizosaccharomyces pombe). Retrovirology 2007; 4:16. [PMID: 17341318 PMCID: PMC1828740 DOI: 10.1186/1742-4690-4-16] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2007] [Accepted: 03/07/2007] [Indexed: 01/08/2023] Open
Abstract
Background Expression of the HIV-1 vpr gene in human and fission yeast cells displays multiple highly conserved activities, which include induction of cell cycle G2 arrest and cell death. We have previously characterized a yeast heat shock protein 16 (Hsp16) that suppresses the Vpr activities when it is overproduced in fission yeast. Similar suppressive effects were observed when the fission yeast hsp16 gene was overexpressed in human cells or in the context of viral infection. In this study, we further characterized molecular actions underlying the suppressive effect of Hsp16 on the Vpr activities. Results We show that the suppressive effect of Hsp16 on Vpr-dependent viral replication in proliferating T-lymphocytes is mediated through its C-terminal end. In addition, we show that Hsp16 inhibits viral infection in macrophages in a dose-dependent manner. Mechanistically, Hsp16 suppresses Vpr activities in a way that resembles the cellular heat shock response. In particular, Hsp16 activation is mediated by a heat shock factor (Hsf)-dependent mechanism. Interestingly, vpr gene expression elicits a moderate increase of endogenous Hsp16 but prevents its elevation when cells are grown under heat shock conditions that normally stimulate Hsp16 production. Similar responsive to Vpr elevation of Hsp and counteraction of this elevation by Vpr were also observed in our parallel mammalian studies. Since Hsf-mediated elevation of small Hsps occurs in all eukaryotes, this finding suggests that the anti-Vpr activity of Hsps is a conserved feature of these proteins. Conclusion These data suggest that fission yeast could be used as a model to further delineate the potential dynamic and antagonistic interactions between HIV-1 Vpr and cellular heat shock responses involving Hsps.
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Affiliation(s)
- Zsigmond Benko
- Children's Memorial Research Center, Departments of Pediatrics, Microbiology-Immunology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Dong Liang
- Children's Memorial Research Center, Departments of Pediatrics, Microbiology-Immunology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
- Departments of Pathology, Microbiology-Immunology, Institute of Human Virology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Emmanuel Agbottah
- Department of Microbiology and Tropical Medicine, George Washington University, Washington, DC, USA
| | - Jason Hou
- Children's Memorial Research Center, Departments of Pediatrics, Microbiology-Immunology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Lorena Taricani
- Department of Biology, Queen's University, Kingston, Ontario, Canada
| | - Paul G Young
- Department of Biology, Queen's University, Kingston, Ontario, Canada
| | - Michael Bukrinsky
- Department of Microbiology and Tropical Medicine, George Washington University, Washington, DC, USA
| | - Richard Y Zhao
- Children's Memorial Research Center, Departments of Pediatrics, Microbiology-Immunology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
- Departments of Pathology, Microbiology-Immunology, Institute of Human Virology, University of Maryland School of Medicine, Baltimore, Maryland, USA
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Desfarges S, San Filippo J, Fournier M, Calmels C, Caumont-Sarcos A, Litvak S, Sung P, Parissi V. Chromosomal integration of LTR-flanked DNA in yeast expressing HIV-1 integrase: down regulation by RAD51. Nucleic Acids Res 2006; 34:6215-24. [PMID: 17090598 PMCID: PMC1693895 DOI: 10.1093/nar/gkl843] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
HIV-1 integrase (IN) is the key enzyme catalyzing the proviral DNA integration step. Although the enzyme catalyzes the integration step accurately in vitro, whether IN is sufficient for in vivo integration and how it interacts with the cellular machinery remains unclear. We set up a yeast cellular integration system where integrase was expressed as the sole HIV-1 protein and targeted the chromosomes. In this simple eukaryotic model, integrase is necessary and sufficient for the insertion of a DNA containing viral LTRs into the genome, thereby allowing the study of the isolated integration step independently of other viral mechanisms. Furthermore, the yeast system was used to identify cellular mechanisms involved in the integration step and allowed us to show the role of homologous recombination systems. We demonstrated physical interactions between HIV-1 IN and RAD51 protein and showed that HIV-1 integrase activity could be inhibited both in the cell and in vitro by RAD51 protein. Our data allowed the identification of RAD51 as a novel in vitro IN cofactor able to down regulate the activity of this retroviral enzyme, thereby acting as a potential cellular restriction factor to HIV infection.
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Affiliation(s)
- S. Desfarges
- UMR 5097-CNRS, BordeauxFrance
- Université Victor Segalen Bordeaux 2, BordeauxFrance
- IFR 66 ‘Pathologies Infectieuses et Cancers’, BordeauxFrance
- 146 rue Léo Saignat, 33076 Bordeaux cedexFrance
| | - J. San Filippo
- Deptartment of Molecular Biophysics and Biochemistry, Yale University School of Medicine333 Cedar Street, SHM C130, New Haven, CT 06520, USA
| | - M. Fournier
- UMR 5097-CNRS, BordeauxFrance
- Université Victor Segalen Bordeaux 2, BordeauxFrance
- IFR 66 ‘Pathologies Infectieuses et Cancers’, BordeauxFrance
- 146 rue Léo Saignat, 33076 Bordeaux cedexFrance
| | - C. Calmels
- UMR 5097-CNRS, BordeauxFrance
- Université Victor Segalen Bordeaux 2, BordeauxFrance
- IFR 66 ‘Pathologies Infectieuses et Cancers’, BordeauxFrance
- 146 rue Léo Saignat, 33076 Bordeaux cedexFrance
| | - A. Caumont-Sarcos
- UMR 5097-CNRS, BordeauxFrance
- Université Victor Segalen Bordeaux 2, BordeauxFrance
- IFR 66 ‘Pathologies Infectieuses et Cancers’, BordeauxFrance
- 146 rue Léo Saignat, 33076 Bordeaux cedexFrance
| | - S. Litvak
- UMR 5097-CNRS, BordeauxFrance
- Université Victor Segalen Bordeaux 2, BordeauxFrance
- IFR 66 ‘Pathologies Infectieuses et Cancers’, BordeauxFrance
- 146 rue Léo Saignat, 33076 Bordeaux cedexFrance
| | - P. Sung
- Deptartment of Molecular Biophysics and Biochemistry, Yale University School of Medicine333 Cedar Street, SHM C130, New Haven, CT 06520, USA
| | - V. Parissi
- UMR 5097-CNRS, BordeauxFrance
- Université Victor Segalen Bordeaux 2, BordeauxFrance
- IFR 66 ‘Pathologies Infectieuses et Cancers’, BordeauxFrance
- 146 rue Léo Saignat, 33076 Bordeaux cedexFrance
- To whom correspondence should be addressed. Tel: +33 5 57 57 1740; Fax: +33 5 57 57 1766;
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Watanabe N, Nishihara Y, Yamaguchi T, Koito A, Miyoshi H, Kakeya H, Osada H. Fumagillin suppresses HIV-1 infection of macrophages through the inhibition of Vpr activity. FEBS Lett 2006; 580:2598-602. [PMID: 16631749 DOI: 10.1016/j.febslet.2006.04.007] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2006] [Revised: 03/23/2006] [Accepted: 04/03/2006] [Indexed: 11/16/2022]
Abstract
HIV-1 viral protein R (Vpr) is one of the human immunodeficiency virus type 1 encoded proteins that have important roles in viral pathogenesis. However, no clinical drug for AIDS therapy that targets Vpr has been developed. Here, we have established a screening system to isolate Vpr inhibitors using budding yeast cells. We purified a Vpr inhibitory compound from fungal metabolites and identified it as fumagillin, a chemical already known to be a potent inhibitor of angiogenesis. Fumagillin not only reversed the growth inhibitory activity of Vpr in yeast and human cells, but also inhibited Vpr-dependent viral gene expression upon the infection of human macrophages.
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Affiliation(s)
- Nobumoto Watanabe
- Antibiotics Laboratory, Discovery Research Institute, RIKEN, 2-1, Hirosawa, Wako, 351-0198, Japan.
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Nakazawa J, Watanabe N, Imoto M, Osada H. Mutational analysis of growth arrest and cellular localization of human immunodeficiency virus type 1 Vpr in the budding yeast, Saccharomyces cerevisiae. J GEN APPL MICROBIOL 2005; 51:245-56. [PMID: 16205032 DOI: 10.2323/jgam.51.245] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Viral protein R (Vpr), one of the accessory gene products of human immunodeficiency virus type 1 (HIV-1), is responsible for the incorporation of a viral genome into the nucleus upon infection. Vpr also arrests the cell cycle and induces apoptosis in infected cells. Similarly, in yeast, Vpr localizes in the nucleus and shows growth inhibitory activity; however, the molecular mechanism of growth inhibition remains unknown. To elucidate this mechanism, several point mutations of Vpr, which are known to perturb several phenotypes of Vpr in mammalian cells, were introduced in the budding yeast, Saccharomyces cerevisiae. For the first time, we found that growth inhibition by Vpr occurred independently of intracellular localization in yeast, as has previously been reported in mammals. We also identified several amino acid residues, the mutation of which cancels growth inhibitory activity, and/or alters localization, both in yeast and mammalian cells, suggesting the importance of these residues for the phenotypes.
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Affiliation(s)
- Junko Nakazawa
- Antibiotics Laboratory, Discovery Research Institute, RIKEN, Wako, Saitama, Japan
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11
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Yoshizuka N, Yoshizuka-Chadani Y, Krishnan V, Zeichner SL. Human immunodeficiency virus type 1 Vpr-dependent cell cycle arrest through a mitogen-activated protein kinase signal transduction pathway. J Virol 2005; 79:11366-81. [PMID: 16103188 PMCID: PMC1193619 DOI: 10.1128/jvi.79.17.11366-11381.2005] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The human immunodeficiency virus type 1 (HIV-1) Vpr protein has important functions in advancing HIV pathogenesis via several effects on the host cell. Vpr mediates nuclear import of the preintegration complex, induces host cell apoptosis, and inhibits cell cycle progression at G(2), which increases HIV gene expression. Some of Vpr's activities have been well described, but some functions, such as cell cycle arrest, are not yet completely characterized, although components of the ATR DNA damage repair pathway and the Cdc25C and Cdc2 cell cycle control mechanisms clearly play important roles. We investigated the mechanisms underlying Vpr-mediated cell cycle arrest by examining global cellular gene expression profiles in cell lines that inducibly express wild-type and mutant Vpr proteins. We found that Vpr expression is associated with the down-regulation of genes in the MEK2-ERK pathway and with decreased phosphorylation of the MEK2 effector protein ERK. Exogenous provision of excess MEK2 reverses the cell cycle arrest associated with Vpr, confirming the involvement of the MEK2-ERK pathway in Vpr-mediated cell cycle arrest. Vpr therefore appears to arrest the cell cycle at G(2)/M through two different mechanisms, the ATR mechanism and a newly described MEK2 mechanism. This redundancy suggests that Vpr-mediated cell cycle arrest is important for HIV replication and pathogenesis. Our findings additionally reinforce the idea that HIV can optimize the host cell environment for viral replication.
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Affiliation(s)
- Naoto Yoshizuka
- HIV and AIDS Malignancy Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20817, USA
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12
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Zhu H, Jian H, Zhao LJ. Identification of the 15FRFG domain in HIV-1 Gag p6 essential for Vpr packaging into the virion. Retrovirology 2004; 1:26. [PMID: 15363109 PMCID: PMC521086 DOI: 10.1186/1742-4690-1-26] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2004] [Accepted: 09/13/2004] [Indexed: 01/15/2023] Open
Abstract
The auxiliary regulatory protein Vpr of HIV-1 is packaged in the virion through interaction with the Gag C-terminal p6 domain. Virion packaging of Vpr is critical for Vpr to exert functions in the HIV-1 life cycle. Previous studies suggest that Vpr interacts with a (Lxx)4 domain in p6 for virion packaging. In the present study, mutational analysis of HIV-1 Gag p6 domain was performed in the context of the HIV-1 genome to examine the effect on virion packaging of Vpr. Surprisingly, Ala substitutions for Leu44 and Phe45 in the (Lxx)4 domain or deletion of the whole (Lxx)4 domain (amino acid #35–52 of the Gag p6 domain) did not affect Vpr virion packaging. Vpr virion packaging was normal when amino acid #1–23 of the Gag p6 domain was preserved. Most importantly, Ala substitutions for Phe15, Arg16 and Phe17 in the context of amino acid #1–23 of the Gag p6 domain abolished Vpr virion packaging. Single Ala substitutions for Phe15 and Phe17 also abolished Vpr virion packaging, whereas Ala substitution for Arg16 had no effect. Our studies have revealed a novel signal sequence for Vpr packaging into the HIV-1 virion. The 15FRFG domain in p6 resembles the FxFG repeat sequences commonly found in proteins of the nuclear pore complex. These results have provided novel insights into the process of virion packaging of Vpr and suggest for the first time that Vpr may recognize the FxFG domain for both virion packaging and association with nuclear pores.
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Affiliation(s)
- Henghu Zhu
- Institute for Molecular Virology, St. Louis University School of Medicine, St. Louis, USA
| | - Heng Jian
- Institute for Molecular Virology, St. Louis University School of Medicine, St. Louis, USA
- Department of Plant Pathology, China Agricultural University, Beijing, China
| | - Ling-Jun Zhao
- Institute for Molecular Virology, St. Louis University School of Medicine, St. Louis, USA
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