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Marrero-Hernández S, Márquez-Arce D, Cabrera-Rodríguez R, Estévez-Herrera J, Pérez-Yanes S, Barroso-González J, Madrid R, Machado JD, Blanco J, Valenzuela-Fernández A. HIV-1 Nef Targets HDAC6 to Assure Viral Production and Virus Infection. Front Microbiol 2019; 10:2437. [PMID: 31736889 PMCID: PMC6831784 DOI: 10.3389/fmicb.2019.02437] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 10/10/2019] [Indexed: 12/11/2022] Open
Abstract
HIV Nef is a central auxiliary protein in HIV infection and pathogenesis. Our results indicate that HDAC6 promotes the aggresome/autophagic degradation of the viral polyprotein Pr55Gag to inhibit HIV-1 production. Nef counteracts this antiviral activity of HDAC6 by inducing its degradation and subsequently stabilizing Pr55Gag and Vif viral proteins. Nef appears to neutralize HDAC6 by an acidic/endosomal-lysosomal processing and does not need the downregulation function, since data obtained with the non-associated cell-surface Nef-G2A mutant - the cytoplasmic location of HDAC6 - together with studies with chemical inhibitors and other Nef mutants, point to this direction. Hence, the polyproline rich region P72xxP75 (69-77 aa) and the di-Leucin motif in the Nef-ExxxLL160-165 sequence of Nef, appear to be responsible for HDAC6 clearance and, therefore, required for this novel Nef proviral function. Nef and Nef-G2A co-immunoprecipitate with HDAC6, whereas the Nef-PPAA mutant showed a reduced interaction with the anti-HIV-1 enzyme. Thus, the P72xxP75 motif appears to be responsible, directly or indirectly, for the interaction of Nef with HDAC6. Remarkably, by neutralizing HDAC6, Nef assures Pr55Gag location and aggregation at plasma membrane, as observed by TIRFM, promotes viral egress, and enhances the infectivity of viral particles. Consequently, our results suggest that HDAC6 acts as an anti-HIV-1 restriction factor, limiting viral production and infection by targeting Pr55Gag and Vif. This function is counteracted by functional HIV-1 Nef, in order to assure viral production and infection capacities. The interplay between HIV-1 Nef and cellular HDAC6 may determine viral infection and pathogenesis, representing both molecules as key targets to battling HIV.
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Affiliation(s)
- Sara Marrero-Hernández
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Sección de Medicina, Facultad de Medicina, Universidad de La Laguna (ULL), La Laguna, Spain.,Unidad Virología y Microbiología del IUETSPC, Universidad de La Laguna (ULL), La Laguna, Spain
| | - Daniel Márquez-Arce
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Sección de Medicina, Facultad de Medicina, Universidad de La Laguna (ULL), La Laguna, Spain.,Unidad Virología y Microbiología del IUETSPC, Universidad de La Laguna (ULL), La Laguna, Spain
| | - Romina Cabrera-Rodríguez
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Sección de Medicina, Facultad de Medicina, Universidad de La Laguna (ULL), La Laguna, Spain.,Unidad Virología y Microbiología del IUETSPC, Universidad de La Laguna (ULL), La Laguna, Spain
| | - Judith Estévez-Herrera
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Sección de Medicina, Facultad de Medicina, Universidad de La Laguna (ULL), La Laguna, Spain.,Unidad Virología y Microbiología del IUETSPC, Universidad de La Laguna (ULL), La Laguna, Spain
| | - Silvia Pérez-Yanes
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Sección de Medicina, Facultad de Medicina, Universidad de La Laguna (ULL), La Laguna, Spain.,Unidad Virología y Microbiología del IUETSPC, Universidad de La Laguna (ULL), La Laguna, Spain
| | - Jonathan Barroso-González
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Sección de Medicina, Facultad de Medicina, Universidad de La Laguna (ULL), La Laguna, Spain
| | - Ricardo Madrid
- BioAssays SL, Campus de Cantoblanco, Madrid, Spain.,Departmento de Genética, Fisiología y Microbiología, Facultad de Biología, Universidad Complutense de Madrid (UCM), Madrid, Spain
| | - José-David Machado
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Sección de Medicina, Facultad de Medicina, Universidad de La Laguna (ULL), La Laguna, Spain
| | - Julià Blanco
- AIDS Research Institute IrsiCaixa, Institut de Recerca en Ciències de la Salut Germans Trias i Pujol (IGTP), Badalona, Spain.,Universitat de Vic-Central de Catalunya, UVIC-UCC, Catalonia, Spain
| | - Agustín Valenzuela-Fernández
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Sección de Medicina, Facultad de Medicina, Universidad de La Laguna (ULL), La Laguna, Spain.,Unidad Virología y Microbiología del IUETSPC, Universidad de La Laguna (ULL), La Laguna, Spain
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2
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Saribas AS, Coric P, Bouaziz S, Safak M. Expression of novel proteins by polyomaviruses and recent advances in the structural and functional features of agnoprotein of JC virus, BK virus, and simian virus 40. J Cell Physiol 2018; 234:8295-8315. [PMID: 30390301 DOI: 10.1002/jcp.27715] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Accepted: 10/18/2018] [Indexed: 12/30/2022]
Abstract
Polyomavirus family consists of a highly diverse group of small DNA viruses. The founding family member (MPyV) was first discovered in the newborn mouse in the late 1950s, which induces solid tumors in a wide variety of tissue types that are the epithelial and mesenchymal origin. Later, other family members were also isolated from a number of mammalian, avian and fish species. Some of these viruses significantly contributed to our current understanding of the fundamentals of modern biology such as transcription, replication, splicing, RNA editing, and cell transformation. After the discovery of first two human polyomaviruses (JC virus [JCV] and BK virus [BKV]) in the early 1970s, there has been a rapid expansion in the number of human polyomaviruses in recent years due to the availability of the new technologies and brought the present number to 14. Some of the human polyomaviruses cause considerably serious human diseases, including progressive multifocal leukoencephalopathy, polyomavirus-associated nephropathy, Merkel cell carcinoma, and trichodysplasia spinulosa. Emerging evidence suggests that the expression of the polyomavirus genome is more complex than previously thought. In addition to encoding universally expressed regulatory and structural proteins (LT-Ag, Sm t-Ag, VP1, VP2, and VP3), some polyomaviruses express additional virus-specific regulatory proteins and microRNAs. This review summarizes the recent advances in polyomavirus genome expression with respect to the new viral proteins and microRNAs other than the universally expressed ones. In addition, a special emphasis is devoted to the recent structural and functional discoveries in the field of polyomavirus agnoprotein which is expressed only by JCV, BKV, and simian virus 40 genomes.
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Affiliation(s)
- A Sami Saribas
- Laboratory of Molecular Neurovirology, Department of Neuroscience, Lewis Katz School of Medicine at Temple University, Philadelphia, Pennsylvania
| | - Pascale Coric
- Laboratoire de Cristallographie et RMN Biologiques, Université Paris Descartes, Sorbonne Paris Cité, UMR 8015 CNRS, Paris, France
| | - Serge Bouaziz
- Laboratoire de Cristallographie et RMN Biologiques, Université Paris Descartes, Sorbonne Paris Cité, UMR 8015 CNRS, Paris, France
| | - Mahmut Safak
- Laboratory of Molecular Neurovirology, Department of Neuroscience, Lewis Katz School of Medicine at Temple University, Philadelphia, Pennsylvania
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3
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Schmitt K, Mohan Kumar D, Curlin J, Remling-Mulder L, Stenglein M, O'Connor S, Marx P, Akkina R. Modeling the evolution of SIV sooty mangabey progenitor virus towards HIV-2 using humanized mice. Virology 2017; 510:175-184. [PMID: 28750321 PMCID: PMC5906053 DOI: 10.1016/j.virol.2017.07.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 07/03/2017] [Accepted: 07/05/2017] [Indexed: 11/27/2022]
Abstract
HIV-2 is thought to have originated from an SIV progenitor native to sooty mangabeys. To model the initial human transmission and understand the sequential viral evolution, humanized mice were infected with SIVsm and serially passaged for five generations. Productive infection was seen by week 3 during the initial challenge followed by chronic viremia and gradual CD4+ T cell decline. Viral loads increased by the 5th generation resulting in more rapid CD4+ T cell decline. Genetic analysis revealed several amino acid substitutions that were nonsynonymous and fixed in multiple hu-mice across each of the 5 generations in the nef, env and rev regions. The highest rate of substitution occurred in the nef and env regions and most were observed within the first two generations. These data demonstrated the utility of hu-mice in modeling the SIVsm transmission to the human and to evaluate its potential sequential evolution into a human pathogen of HIV-2 lineage.
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Affiliation(s)
- Kimberly Schmitt
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523, USA
| | - Dipu Mohan Kumar
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523, USA
| | - James Curlin
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523, USA
| | - Leila Remling-Mulder
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523, USA
| | - Mark Stenglein
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523, USA
| | - Shelby O'Connor
- University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Preston Marx
- Department of Tropical Medicine, School Public Health and Tropical Medicine, New Orleans, LA 70112, USA; Tulane National Primate Research Center, Covington, LA 70433, USA
| | - Ramesh Akkina
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523, USA.
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4
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Saribas AS, Coric P, Hamazaspyan A, Davis W, Axman R, White MK, Abou-Gharbia M, Childers W, Condra JH, Bouaziz S, Safak M. Emerging From the Unknown: Structural and Functional Features of Agnoprotein of Polyomaviruses. J Cell Physiol 2016; 231:2115-27. [PMID: 26831433 DOI: 10.1002/jcp.25329] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 02/01/2016] [Indexed: 12/15/2022]
Abstract
Agnoprotein is an important regulatory protein of polyomaviruses, including JCV, BKV, and SV40. In the absence of its expression, these viruses are unable to sustain their productive life cycle. It is a highly basic phosphoprotein that localizes mostly to the perinuclear area of infected cells, although a small amount of the protein is also found in nucleus. Much has been learned about the structure and function of this important regulatory protein in recent years. It forms highly stable dimers/oligomers in vitro and in vivo through its Leu/Ile/Phe-rich domain. Structural NMR studies revealed that this domain adopts an alpha-helix conformation and plays a critical role in the stability of the protein. It associates with cellular proteins, including YB-1, p53, Ku70, FEZ1, HP1α, PP2A, AP-3, PCNA, and α-SNAP; and viral proteins, including small t antigen, large T antigen, HIV-1 Tat, and JCV VP1; and significantly contributes the viral transcription and replication. This review summarizes the recent advances in the structural and functional properties of this important regulatory protein. J. Cell. Physiol. 231: 2115-2127, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- A Sami Saribas
- Department of Neuroscience, Laboratory of Molecular Neurovirology, MERB-757, Temple University Lewis Katz School of Medicine, Philadelphia, Pennsylvania
| | - Pascale Coric
- Université Paris Descartes, Sorbonne Paris Cité, Laboratoire de Cristallographie et RMN Biologiques, 4 av. de l'Observatoire, Paris, France
| | - Anahit Hamazaspyan
- Department of Neuroscience, Laboratory of Molecular Neurovirology, MERB-757, Temple University Lewis Katz School of Medicine, Philadelphia, Pennsylvania
| | - William Davis
- Department of Neuroscience, Laboratory of Molecular Neurovirology, MERB-757, Temple University Lewis Katz School of Medicine, Philadelphia, Pennsylvania
| | - Rachel Axman
- Department of Neuroscience, Laboratory of Molecular Neurovirology, MERB-757, Temple University Lewis Katz School of Medicine, Philadelphia, Pennsylvania
| | - Martyn K White
- Department of Neuroscience, Laboratory of Molecular Neurovirology, MERB-757, Temple University Lewis Katz School of Medicine, Philadelphia, Pennsylvania
| | - Magid Abou-Gharbia
- Moulder Center for Drug Discovery Research, Temple University School of Pharmacy, Philadelphia, Pennsylvania
| | - Wayne Childers
- Moulder Center for Drug Discovery Research, Temple University School of Pharmacy, Philadelphia, Pennsylvania
| | - Jon H Condra
- Moulder Center for Drug Discovery Research, Temple University School of Pharmacy, Philadelphia, Pennsylvania
| | - Serge Bouaziz
- Université Paris Descartes, Sorbonne Paris Cité, Laboratoire de Cristallographie et RMN Biologiques, 4 av. de l'Observatoire, Paris, France
| | - Mahmut Safak
- Department of Neuroscience, Laboratory of Molecular Neurovirology, MERB-757, Temple University Lewis Katz School of Medicine, Philadelphia, Pennsylvania
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Consequences of HLA-B*13-Associated Escape Mutations on HIV-1 Replication and Nef Function. J Virol 2015; 89:11557-71. [PMID: 26355081 DOI: 10.1128/jvi.01955-15] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 08/31/2015] [Indexed: 01/05/2023] Open
Abstract
UNLABELLED HLA-B*13 is associated with superior in vivo HIV-1 viremia control. Protection is thought to be mediated by sustained targeting of key cytotoxic T lymphocyte (CTL) epitopes and viral fitness costs of CTL escape in Gag although additional factors may contribute. We assessed the impact of 10 published B*13-associated polymorphisms in Gag, Pol, and Nef, in 23 biologically relevant combinations, on HIV-1 replication capacity and Nef-mediated reduction of cell surface CD4 and HLA class I expression. Mutations were engineered into HIV-1NL4.3, and replication capacity was measured using a green fluorescent protein (GFP) reporter T cell line. Nef-mediated CD4 and HLA-A*02 downregulation was assessed by flow cytometry, and T cell recognition of infected target cells was measured via coculture with an HIV-specific luciferase reporter cell line. When tested individually, only Gag-I147L and Gag-I437L incurred replicative costs (5% and 17%, respectively), consistent with prior reports. The Gag-I437L-mediated replication defect was rescued to wild-type levels by the adjacent K436R mutation. A novel B*13 epitope, comprising 8 residues and terminating at Gag147, was identified in p24(Gag) (GQMVHQAIGag140-147). No other single or combination Gag, Pol, or Nef mutant impaired viral replication. Single Nef mutations did not affect CD4 or HLA downregulation; however, the Nef double mutant E24Q-Q107R showed 40% impairment in HLA downregulation with no evidence of Nef stability defects. Moreover, target cells infected with HIV-1-NefE24Q-Q107R were recognized better by HIV-specific T cells than those infected with HIV-1NL4.3 or single Nef mutants. Our results indicate that CTL escape in Gag and Nef can be functionally costly and suggest that these effects may contribute to long-term HIV-1 control by HLA-B*13. IMPORTANCE Protective effects of HLA-B*13 on HIV-1 disease progression are mediated in part by fitness costs of CTL escape mutations in conserved Gag epitopes, but other mechanisms remain incompletely known. We extend our knowledge of the impact of B*13-driven escape on HIV-1 replication by identifying Gag-K436R as a compensatory mutation for the fitness-costly Gag-I437L. We also identify Gag-I147L, the most rapidly and commonly selected B*13-driven substitution in HIV-1, as a putative C-terminal anchor residue mutation in a novel B*13 epitope. Most notably, we identify a novel escape-driven fitness defect: B*13-driven substitutions E24Q and Q107R in Nef, when present together, substantially impair this protein's ability to downregulate HLA class I. This, in turn, increases the visibility of infected cells to HIV-specific T cells. Our results suggest that B*13-associated escape mutations impair HIV-1 replication by two distinct mechanisms, that is, by reducing Gag fitness and dampening Nef immune evasion function.
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Fan X, Wei J, Xiong H, Liu X, Benichou S, Gao X, Liu L. A homogeneous time-resolved fluorescence-based high-throughput screening for discovery of inhibitors of Nef-sdAb19 interaction. Int J Oncol 2015; 47:1485-93. [PMID: 26315450 DOI: 10.3892/ijo.2015.3132] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 07/28/2015] [Indexed: 11/05/2022] Open
Abstract
The human immunodeficiency virus (HIV) protein negative factor (Nef) is important for AIDS pathogenesis. An anti-Nef single-domain antibody (sdAb19) derived from camelids has been previously generated and shown to effectively block the physiological functions of Nef in vitro and in vivo in nef-transgenic mice. However, sdAb19 must be ectopically expressed within the target cell to be able to exert its neutralizing effect on Nef, while the extra-cellular administration method turned out to be ineffective. This might suggest a default of the stability or/and deliverability of sdAb19. The identification of small molecule compounds capable of inhibiting the Nef-sdAb19 interaction and mimicking the neutralizing activity of sdAb19 in vivo would therefore be the means of circumventing the problem encountered with sdAb19. Here we describe the development of a high-throughput screening method combining the homogeneous time-resolved fluorescence (HTRF) and the microscale thermophoresis (MST) techniques for the identification of small-molecule compounds inhibiting the Nef-sdAb19 interaction by binding to Nef protein. Eight small-molecule compounds have been selected for their ability to significantly inhibit the Nef-sdAb19 interaction and to bind to Nef. These molecules could be further assessed for their potential of being the Nef-neutralizing agents in the future.
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Affiliation(s)
- Xiaoqin Fan
- Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, Jinan University, Guangzhou 510632, P.R. China
| | - Jinmei Wei
- Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, Jinan University, Guangzhou 510632, P.R. China
| | - Haiting Xiong
- Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, Jinan University, Guangzhou 510632, P.R. China
| | - Xiaohui Liu
- Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, Jinan University, Guangzhou 510632, P.R. China
| | - Serge Benichou
- Cochin Institute, INSERM U1016, Centre National de la Recherche Scientifique UMR8104, Université Paris-Descartes, Paris, France
| | - Xuejuan Gao
- Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, Jinan University, Guangzhou 510632, P.R. China
| | - Langxia Liu
- Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, Jinan University, Guangzhou 510632, P.R. China
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Pramanik S, Kutzner A, Heese K. 3D Structure, Dimerization Modeling, and Lead Discovery by Ligand-protein Interaction Analysis of p60 Transcription Regulator Protein (p60TRP). Mol Inform 2015; 35:99-108. [DOI: 10.1002/minf.201500035] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Accepted: 05/20/2015] [Indexed: 12/28/2022]
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HIV-1 Env and Nef Cooperatively Contribute to Plasmacytoid Dendritic Cell Activation via CD4-Dependent Mechanisms. J Virol 2015; 89:7604-11. [PMID: 25972534 DOI: 10.1128/jvi.00695-15] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 05/05/2015] [Indexed: 12/14/2022] Open
Abstract
UNLABELLED Plasmacytoid dendritic cells (pDCs) are the major source of type I IFN (IFN-I) in response to human immunodeficiency virus type 1 (HIV-1) infection. pDCs are rapidly activated during HIV-1 infection and are implicated in reducing the early viral load, as well as contributing to HIV-1-induced pathogenesis. However, most cell-free HIV-1 isolates are inefficient in activating human pDCs, and the mechanisms of HIV-1 recognition by pDCs and pDC activation are not clearly defined. In this study, we report that two genetically similar HIV-1 variants (R3A and R3B) isolated from a rapid progressor differentially activated pDCs to produce alpha interferon (IFN-α). The highly pathogenic R3A efficiently activated pDCs to induce robust IFN-α production, while the less pathogenic R3B did not. The viral determinant for efficient pDC activation was mapped to the V1V2 region of R3A Env, which also correlated with enhanced CD4 binding activity. Furthermore, we showed that the Nef protein was also required for the activation of pDCs by R3A. Analysis of a panel of R3A Nef functional mutants demonstrated that Nef domains involved in CD4 downregulation were necessary for R3A to activate pDCs. Our data indicate that R3A-induced pDC activation depends on (i) the high affinity of R3A Env for binding the CD4 receptor and (ii) Nef activity, which is involved in CD4 downregulation. Our findings provide new insights into the mechanism by which HIV-1 induces IFN-α in pDCs, which contributes to pathogenesis. IMPORTANCE Plasmacytoid dendritic cells (pDCs) are the major type I interferon (IFN-I)-producing cells, and IFN-I actually contributes to pathogenesis during chronic viral infections. How HIV-1 activates pDCs and the roles of pDCs/IFN-I in HIV-1 pathogenesis remain unclear. We report here that the highly pathogenic HIV R3A efficiently activated pDCs to induce IFN-α production, while most HIV-1 isolates are inefficient in activating pDCs. We have discovered that R3A-induced pDC activation depends on (i) the high affinity of R3A Env for binding the CD4 receptor and (ii) Nef activity, which is involved in CD4 downregulation. Our findings thus provide new insights into the mechanism by which HIV-1 induces IFN-α in pDCs and contributes to HIV-1 pathogenesis. These novel findings will be of great interest to those working on the roles of IFN and pDCs in HIV-1 pathogenesis in general and on the interaction of HIV-1 with pDCs in particular.
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9
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Damtie D, Yismaw G, Woldeyohannes D, Anagaw B. Common opportunistic infections and their CD4 cell correlates among HIV-infected patients attending at antiretroviral therapy clinic of Gondar University Hospital, Northwest Ethiopia. BMC Res Notes 2013; 6:534. [PMID: 24330921 PMCID: PMC3866565 DOI: 10.1186/1756-0500-6-534] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Accepted: 12/10/2013] [Indexed: 11/12/2022] Open
Abstract
Background Human immunodeficiency virus (HIV) pandemic is among the greatest health crises ever faced by humanity. Morbidity and mortality in HIV disease is due to immunosuppression leading to life-threatening opportunistic infections (OIs) during the natural course of the disease. This study was aimed to assess the prevalence and CD4 correlates of OIs among adult HIV-infected patients attending at Gondar University Hospital. Methods Cross sectional study was conducted on 360 adult HIV-infected patients attending antiretroviral therapy clinic from February 2012-April 2012. Patients’ OI status was determined through clinical diagnosis and laboratory investigations. CD4 count was determined using flow cytometry technique. Sociodemographic and clinical data were obtained from interview and patients’ medical records. Bivariate and multivariate logistic regression analysis was done using SPSS version 16 statistical soft ware and odds ratio was used as the measure of association. P-value less than 0.05 was considered statistically significant for all tests. Results In this study, 360 HIV-infected patients were included; of whom (n = 216/360, 60%) were females. The majority of patients (n = 153/360, 42.5%) were 25-34 years old with mean age of 35.5+ 8.8 standard deviation. The overall prevalence of OIs was (n = 71/360, 19.7%). Tuberculosis (n = 35/360, 9.72%) followed by oral candidiasis (n = 18/360, 5%) and diarrhea (n = 12/360, 3.3%) were the most frequently observed OIs. CD4 count less than 200/mm3 (OR = 4.933, P < 0.001), World Health Organization (WHO) clinical stage III (OR = 9.418, P < 0.001) and IV (OR = 22.665, P < 0.001) were found to have strong association with acquisition of OIs. Conclusions Tuberculosis, oral candidiasis and diarrhea were the leading OIs encountered by HIV-infected patients. CD4 count less than 200/mm3 and advanced WHO clinical stages of the disease were found to be predictors of OIs. Interventions aimed at preventing and treating HIV associated OIs are crucial. Initiation of ART before the CD4 count drops below 350 should be encouraged.
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Affiliation(s)
- Debasu Damtie
- Department of Immunology and Molecular biology, School of Biomedical and Laboratory Sciences, College of Medicine and Health Sciences, University of Gondar, Gondar, Ethiopia.
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Cruz NVG, Amorim R, Oliveira FE, Speranza FAC, Costa LJ. Mutations in the nef and vif genes associated with progression to AIDS in elite controller and slow-progressor patients. J Med Virol 2013; 85:563-74. [PMID: 23417613 DOI: 10.1002/jmv.23512] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/26/2012] [Indexed: 11/07/2022]
Abstract
Progression towards AIDS can vary from 5 to 10 years from the establishment of the primary infection by HIV-1 to more than 10 years in the complete absence of antiretroviral therapy. Several factors can contribute to the outcome of HIV infection, including host genetic and viral replicating characteristics. Historically, nef-deleted viral genomes have been associated with disease progression. Therefore, the lentiviral Nef protein is regarded as a progression factor. The objective of this work was to characterize the nef gene from a group of treatment naive patients infected with HIV-1 for more than 10 years. These patients were classified as long-term non-progressors, elite controller, and slow-progressors according to clinical and laboratorial data. A premature stop codon within the nef gene leading to the expression of a truncated peptide was observed on samples from the elite controller patient. For the slow-progressor patients, several degrees of deletions at the C-terminal of Nef were observed predicting a loss of function of this protein. The vif gene was characterized for these patients and a rare mutation that predicts a miss localization of the Vif protein to the nucleus of infected cells that could prevent its function as an APOBEC neutralization factor was also observed. These data indicate the importance of the HIV accessory proteins as factors that contribute to the outcome of AIDS.
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Affiliation(s)
- Nadia V G Cruz
- Department of Virology, Institute of Microbiology Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
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11
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Kammula EC, Mötter J, Gorgels A, Jonas E, Hoffmann S, Willbold D. Brain transcriptome-wide screen for HIV-1 Nef protein interaction partners reveals various membrane-associated proteins. PLoS One 2012; 7:e51578. [PMID: 23284715 PMCID: PMC3524239 DOI: 10.1371/journal.pone.0051578] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Accepted: 11/02/2012] [Indexed: 01/23/2023] Open
Abstract
HIV-1 Nef protein contributes essentially to the pathology of AIDS by a variety of protein-protein-interactions within the host cell. The versatile functionality of Nef is partially attributed to different conformational states and posttranslational modifications, such as myristoylation. Up to now, many interaction partners of Nef have been identified using classical yeast two-hybrid screens. Such screens rely on transcriptional activation of reporter genes in the nucleus to detect interactions. Thus, the identification of Nef interaction partners that are integral membrane proteins, membrane-associated proteins or other proteins that do not translocate into the nucleus is hampered. In the present study, a split-ubiquitin based yeast two-hybrid screen was used to identify novel membrane-localized interaction partners of Nef. More than 80% of the hereby identified interaction partners of Nef are transmembrane proteins. The identified hits are GPM6B, GPM6A, BAP31, TSPAN7, CYB5B, CD320/TCblR, VSIG4, PMEPA1, OCIAD1, ITGB1, CHN1, PH4, CLDN10, HSPA9, APR-3, PEBP1 and B3GNT, which are involved in diverse cellular processes like signaling, apoptosis, neurogenesis, cell adhesion and protein trafficking or quality control. For a subfraction of the hereby identified proteins we present data supporting their direct interaction with HIV-1 Nef. We discuss the results with respect to many phenotypes observed in HIV infected cells and patients. The identified Nef interaction partners may help to further elucidate the molecular basis of HIV-related diseases.
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Affiliation(s)
- Ellen C. Kammula
- Institute of Complex Systems, ICS-6: Structural Biochemistry, Forschungszentrum Jülich, Jülich, Germany
- Institute of Physical Biology, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany
| | - Jessica Mötter
- Institute of Complex Systems, ICS-6: Structural Biochemistry, Forschungszentrum Jülich, Jülich, Germany
- Institute of Physical Biology, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany
| | - Alexandra Gorgels
- Institute of Complex Systems, ICS-6: Structural Biochemistry, Forschungszentrum Jülich, Jülich, Germany
| | - Esther Jonas
- Institute of Physical Biology, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany
| | - Silke Hoffmann
- Institute of Complex Systems, ICS-6: Structural Biochemistry, Forschungszentrum Jülich, Jülich, Germany
| | - Dieter Willbold
- Institute of Complex Systems, ICS-6: Structural Biochemistry, Forschungszentrum Jülich, Jülich, Germany
- Institute of Physical Biology, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany
- * E-mail:
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Kuo LS, Baugh LL, Denial SJ, Watkins RL, Liu M, Garcia JV, Foster JL. Overlapping effector interfaces define the multiple functions of the HIV-1 Nef polyproline helix. Retrovirology 2012; 9:47. [PMID: 22651890 PMCID: PMC3464899 DOI: 10.1186/1742-4690-9-47] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Accepted: 05/31/2012] [Indexed: 11/20/2022] Open
Abstract
Background HIV-1 Nef is a multifunctional protein required for full pathogenicity of the virus. As Nef has no known enzymatic activity, it necessarily functions through protein-protein interaction interfaces. A critical Nef protein interaction interface is centered on its polyproline segment (P69VRPQVPLRP78) which contains the helical SH3 domain binding protein motif, PXXPXR. We hypothesized that any Nef-SH3 domain interactions would be lost upon mutation of the prolines or arginine of PXXPXR. Further, mutation of the non-motif “X” residues, (Q73, V74, and L75) would give altered patterns of inhibition for different Nef/SH3 domain protein interactions. Results We found that mutations of either of the prolines or the arginine of PXXPXR are defective for Nef-Hck binding, Nef/activated PAK2 complex formation and enhancement of virion infectivity (EVI). Mutation of the non-motif “X” residues (Q, V and L) gave similar patterns of inhibition for Nef/activated PAK2 complex formation and EVI which were distinct from the pattern for Hck binding. These results implicate an SH3 domain containing protein other than Hck for Nef/activated PAK2 complex formation and EVI. We have also mutated Nef residues at the N-and C-terminal ends of the polyproline segment to explore interactions outside of PXXPXR. We discovered a new locus GFP/F (G67, F68, P69 and F90) that is required for Nef/activated PAK2 complex formation and EVI. MHC Class I (MHCI) downregulation was only partially inhibited by mutating the PXXPXR motif residues, but was fully inhibited by mutating the C-terminal P78. Further, we observed that MHCI downregulation strictly requires G67 and F68. Our mutational analysis confirms the recently reported structure of the complex between Nef, AP-1 μ1 and the cytoplasmic tail of MHCI, but does not support involvement of an SH3 domain protein in MHCI downregulation. Conclusion Nef has evolved to be dependent on interactions with multiple SH3 domain proteins. To the N- and C- terminal sides of the polyproline helix are multifunctional protein interaction sites. The polyproline segment is also adapted to downregulate MHCI with a non-canonical binding surface. Our results demonstrate that Nef polyproline helix is highly adapted to directly interact with multiple host cell proteins.
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Affiliation(s)
- Lillian S Kuo
- Department of Internal Medicine, University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Boulevard, Y9.206, Dallas, TX 75390, USA
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Vermeire J, Vanbillemont G, Witkowski W, Verhasselt B. The Nef-infectivity enigma: mechanisms of enhanced lentiviral infection. Curr HIV Res 2012; 9:474-89. [PMID: 22103831 PMCID: PMC3355465 DOI: 10.2174/157016211798842099] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2011] [Revised: 10/24/2011] [Accepted: 10/27/2011] [Indexed: 11/22/2022]
Abstract
The Nef protein is an essential factor for lentiviral pathogenesis in humans and other simians. Despite a multitude of functions attributed to this protein, the exact role of Nef in disease progression remains unclear. One of its most intriguing functions is the ability of Nef to enhance the infectivity of viral particles. In this review we will discuss current insights in the mechanism of this well-known, yet poorly understood Nef effect. We will elaborate on effects of Nef, on both virion biogenesis and the early stage of the cellular infection, that might be involved in infectivity enhancement. In addition, we provide an overview of different HIV-1 Nef domains important for optimal infectivity and briefly discuss some possible sources of the frequent discrepancies in the field. Hereby we aim to contribute to a better understanding of this highly conserved and therapeutically attractive Nef function.
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Affiliation(s)
- Jolien Vermeire
- Department of Clinical Chemistry, Microbiology and Immunology, Ghent University, Belgium
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14
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Singh P, Yadav GP, Gupta S, Tripathi AK, Ramachandran R, Tripathi RK. A novel dimer-tetramer transition captured by the crystal structure of the HIV-1 Nef. PLoS One 2011; 6:e26629. [PMID: 22073177 PMCID: PMC3206816 DOI: 10.1371/journal.pone.0026629] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Accepted: 09/29/2011] [Indexed: 11/19/2022] Open
Abstract
HIV-1 Nef modulates disease progression through interactions with over 30 host proteins. Individual chains fold into membrane-interacting N-terminal and C-terminal core (Nef(core)) domains respectively. Nef exists as small oligomers near membranes and associates into higher oligomers such as tetramers or hexadecamers in the cytoplasm. Earlier structures of the Nef(core) in apo and complexed forms with the Fyn-kinase SH3 domain revealed dimeric association details and the role of the conserved PXXP recognition motif (residues 72-78) of Nef in SH3-domain interactions. The crystal structure of the tetrameric Nef reported here corresponds to the elusive cytoplasmic stage. Comparative analyses show that subunits of Nef(core) dimers (open conformation) swing out with a relative displacement of ~22 Å and rotation of ~174° to form the 'closed' tetrameric structure. The changes to the association are around Asp125, a conserved residue important for viral replication and the important XR motif (residues 107-108). The tetramer associates through C4 symmetry instead of the 222 symmetry expected when two dimers associate together. This novel dimer-tetramer transition agrees with earlier solution studies including small angle X-ray scattering, analytical ultracentrifugation, dynamic laser light scattering and our glutaraldehyde cross-linking experiments. Comparisons with the Nef(core)--Fyn-SH3 domain complexes reveal that the PXXP motif that interacts with the SH3-domain in the dimeric form is sterically occluded in the tetramer. However the 151-180 loop that is distal to the PXXP motif and contains several protein interaction motifs remains accessible. The results suggest how changes to the oligomeric state of Nef can help it distinguish between protein partners.
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Affiliation(s)
- Pankaj Singh
- Toxicology Division, Central Drug Research Institute (Council of Scientific & Industrial Research), Chattar Manzil, Mahatma Gandhi Marg, Lucknow, Uttar Pradesh, India
| | - Gaya Prasad Yadav
- Molecular and Structural Biology Division, Central Drug Research Institute (Council of Scientific & Industrial Research), Chattar Manzil, Mahatma Gandhi Marg, Lucknow, Uttar Pradesh, India
| | - Sudeepti Gupta
- Toxicology Division, Central Drug Research Institute (Council of Scientific & Industrial Research), Chattar Manzil, Mahatma Gandhi Marg, Lucknow, Uttar Pradesh, India
| | - Anil Kumar Tripathi
- Chatrapati Shahuji Maharaj Medical University, Chowk, Lucknow, Uttar Pradesh, India
| | - Ravishankar Ramachandran
- Molecular and Structural Biology Division, Central Drug Research Institute (Council of Scientific & Industrial Research), Chattar Manzil, Mahatma Gandhi Marg, Lucknow, Uttar Pradesh, India
| | - Raj Kamal Tripathi
- Toxicology Division, Central Drug Research Institute (Council of Scientific & Industrial Research), Chattar Manzil, Mahatma Gandhi Marg, Lucknow, Uttar Pradesh, India
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15
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Human polyomavirus JC small regulatory agnoprotein forms highly stable dimers and oligomers: implications for their roles in agnoprotein function. Virology 2011; 420:51-65. [PMID: 21920573 DOI: 10.1016/j.virol.2011.08.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Revised: 08/09/2011] [Accepted: 08/19/2011] [Indexed: 11/22/2022]
Abstract
JC virus (JCV) encodes a small basic phosphoprotein from the late coding region called agnoprotein, which has been shown to play important regulatory roles in the viral replication cycle. In this study, we report that agnoprotein forms highly stable dimers and higher order oligomer complexes. This was confirmed by immunoblotting and mass spectrometry studies. These complexes are extremely resistant to strong denaturing agents, including urea and SDS. Central portion of the protein, amino acids spanning from 17 to 42 is important for dimer/oligomer formation. Removal of 17 to 42 aa region from the viral background severely affected the efficiency of the JCV replication. Extracts prepared from JCV-infected cells showed a double banding pattern for agnoprotein in vivo. Collectively, these findings suggest that agnoprotein forms functionally active homodimer/oligomer complexes and these may be important for its function during viral propagation and thus for the progression of PML.
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16
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Horenkamp FA, Breuer S, Schulte A, Lülf S, Weyand M, Saksela K, Geyer M. Conformation of the dileucine-based sorting motif in HIV-1 Nef revealed by intermolecular domain assembly. Traffic 2011; 12:867-77. [PMID: 21477083 DOI: 10.1111/j.1600-0854.2011.01205.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The human immunodeficiency virus 1 (HIV-1) Nef protein is a pathogenicity factor required for effective progression to AIDS, which modulates host cell signaling pathways and T-cell receptor internalization. We have determined the crystal structure of Nef, allele SF2, in complex with an engineered SH3 domain of human Hck showing unnaturally tight binding and inhibitory potential toward Nef. This complex provides the most complete Nef structure described today, and explains the structural basis of the high affinity of this interaction. Intriguingly, the 33-residue C-terminal flexible loop is resolved in the structure by its interactions with a highly conserved hydrophobic groove on the core domain of an adjacent Nef molecule. The loop mediates the interaction of Nef with the cellular adaptor protein machinery for the stimulated internalization of surface receptors. The endocytic dileucine-based sorting motif is exposed at the tip of the acidic loop, giving the myristoylated Nef protein a distinctly dipolar character. The intermolecular domain assembly of Nef provides insights into a possible regulation mechanism for cargo trafficking.
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Affiliation(s)
- Florian A Horenkamp
- Abteilung Physikalische Biochemie, Max-Planck-Institut für molekulare Physiologie, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany
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Tokarev A, Guatelli J. Misdirection of membrane trafficking by HIV-1 Vpu and Nef: Keys to viral virulence and persistence. CELLULAR LOGISTICS 2011; 1:90-102. [PMID: 21922073 PMCID: PMC3173656 DOI: 10.4161/cl.1.3.16708] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2011] [Revised: 06/14/2011] [Accepted: 06/15/2011] [Indexed: 11/19/2022]
Abstract
The HIV-1 accessory protein Nef is well known for its manipulation of host cell endosomal trafficking. By linking transmembrane proteins to endosomal coats, Nef removes them from the surface of infected cells. Modulation of MHC proteins leads to viral evasion of cellular adaptive immunity, whereas modulation of receptors for the HIV envelope glycoprotein, including CD4, enhances viral infectivity. The other HIV-1 accessory proteins, Vif, Vpr and Vpu, share a mechanism of action distinct from Nef in that each interacts with a multi-subunit ubiquitin ligase complex to target cellular proteins for proteosomal degradation. However, newly uncovered functions and mechanistic aspects of Vpu likely involve endosomal trafficking: these include counteraction of the innate antiviral activity of the cellular transmembrane protein BST-2 (tetherin), as well as the removal of the lipid-antigen presenting protein CD1d and the natural killer cell ligand NTB-A from the cell surface. This review focuses on how Nef and Vpu interfere with normal intracellular membrane trafficking to facilitate the spread and virulence of HIV-1.
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Affiliation(s)
- Andrey Tokarev
- Department of Medicine; University of California, San Diego; and the San Diego Veterans Affairs Healthcare System; La Jolla, CA USA
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Foster JL, Denial SJ, Temple BRS, Garcia JV. Mechanisms of HIV-1 Nef function and intracellular signaling. J Neuroimmune Pharmacol 2011; 6:230-46. [PMID: 21336563 DOI: 10.1007/s11481-011-9262-y] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Accepted: 02/01/2011] [Indexed: 11/29/2022]
Abstract
Advances in the last several years have enhanced mechanistic understanding of Nef-induced CD4 and MHCI downregulation and have suggested a new paradigm for analyzing Nef function. In both of these cases, Nef acts by forming ternary complexes with significant contributions to stability imparted by non-canonical interactions. The mutational analyses and binding assays that have led to these conclusions are discussed. The recent progress has been dependent on conservative mutations and multi-protein binding assays. The poorly understood Nef functions of p21 activated protein kinase (PAK2) activation, enhancement of virion infectivity, and inhibition of immunoglobulin class switching are also likely to involve ternary complexes and non-canonical interactions. Hence, investigation of these latter Nef functions should benefit from a similar approach. Six historically used alanine substitutions for determining structure-function relationships of Nef are discussed. These are M20A, E62A/E63A/E64A/E65A (AAAA), P72A/P75A (AXXA), R106A, L164A/L165A, and D174A/D175A. Investigations of less-disruptive mutations in place of AAAA and AXXA have led to different interpretations of mechanism. Two recent examples of this alternate approach, F191I for studying PAK2 activation and D123E for the critical residue D123 are discussed. The implications of the new findings and the resulting new paradigm for Nef structure-function are discussed with respect to creating a map of Nef functions on the protein surface. We report the results of a PPI-Pred analysis for protein-protein interfaces. There are three predicted patches produced by the analysis which describe regions consistent with the currently known mutational analyses of Nef function.
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Affiliation(s)
- John L Foster
- Division of Infectious Diseases, Center for AIDS Research, Chapel Hill, NC 27599-7042, USA.
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