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Lawrence SP, Elser SE, Torben W, Blair RV, Pahar B, Aye PP, Schiro F, Szeltner D, Doyle-Meyers LA, Haggarty BS, Jordan APO, Romano J, Leslie GJ, Alvarez X, O’Connor DH, Wiseman RW, Fennessey CM, Li Y, Piatak M, Lifson JD, LaBranche CC, Lackner AA, Keele BF, Maness NJ, Marsh M, Hoxie JA. A cellular trafficking signal in the SIV envelope protein cytoplasmic domain is strongly selected for in pathogenic infection. PLoS Pathog 2022; 18:e1010507. [PMID: 35714165 PMCID: PMC9275724 DOI: 10.1371/journal.ppat.1010507] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 07/12/2022] [Accepted: 04/07/2022] [Indexed: 01/01/2023] Open
Abstract
The HIV/SIV envelope glycoprotein (Env) cytoplasmic domain contains a highly conserved Tyr-based trafficking signal that mediates both clathrin-dependent endocytosis and polarized sorting. Despite extensive analysis, the role of these functions in viral infection and pathogenesis is unclear. An SIV molecular clone (SIVmac239) in which this signal is inactivated by deletion of Gly-720 and Tyr-721 (SIVmac239ΔGY), replicates acutely to high levels in pigtail macaques (PTM) but is rapidly controlled. However, we previously reported that rhesus macaques and PTM can progress to AIDS following SIVmac239ΔGY infection in association with novel amino acid changes in the Env cytoplasmic domain. These included an R722G flanking the ΔGY deletion and a nine nucleotide deletion encoding amino acids 734-736 (ΔQTH) that overlaps the rev and tat open reading frames. We show that molecular clones containing these mutations reconstitute signals for both endocytosis and polarized sorting. In one PTM, a novel genotype was selected that generated a new signal for polarized sorting but not endocytosis. This genotype, together with the ΔGY mutation, was conserved in association with high viral loads for several months when introduced into naïve PTMs. For the first time, our findings reveal strong selection pressure for Env endocytosis and particularly for polarized sorting during pathogenic SIV infection in vivo.
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Affiliation(s)
- Scott P. Lawrence
- MRC Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
| | - Samra E. Elser
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Workineh Torben
- Tulane National Primate Research Center, Covington, Louisiana, United States of America
| | - Robert V. Blair
- Tulane National Primate Research Center, Covington, Louisiana, United States of America
| | - Bapi Pahar
- Tulane National Primate Research Center, Covington, Louisiana, United States of America
| | - Pyone P. Aye
- Tulane National Primate Research Center, Covington, Louisiana, United States of America
| | - Faith Schiro
- Tulane National Primate Research Center, Covington, Louisiana, United States of America
| | - Dawn Szeltner
- Tulane National Primate Research Center, Covington, Louisiana, United States of America
| | - Lara A. Doyle-Meyers
- Tulane National Primate Research Center, Covington, Louisiana, United States of America
| | - Beth S. Haggarty
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Andrea P. O. Jordan
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Josephine Romano
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - George J. Leslie
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Xavier Alvarez
- Tulane National Primate Research Center, Covington, Louisiana, United States of America
| | - David H. O’Connor
- Wisconsin National Primate Research Center, Madison, Wisconsin, United States of America
| | - Roger W. Wiseman
- Wisconsin National Primate Research Center, Madison, Wisconsin, United States of America
| | - Christine M. Fennessey
- AIDS and Cancer Virus Program, Frederick National Laboratory for Cancer Research, Frederick, Maryland, United States of America
| | - Yuan Li
- AIDS and Cancer Virus Program, Frederick National Laboratory for Cancer Research, Frederick, Maryland, United States of America
| | - Michael Piatak
- AIDS and Cancer Virus Program, Frederick National Laboratory for Cancer Research, Frederick, Maryland, United States of America
| | - Jeffrey D. Lifson
- AIDS and Cancer Virus Program, Frederick National Laboratory for Cancer Research, Frederick, Maryland, United States of America
| | - Celia C. LaBranche
- Duke University Medical Center, Durham, North Carolina, United States of America
| | - Andrew A. Lackner
- Tulane National Primate Research Center, Covington, Louisiana, United States of America
| | - Brandon F. Keele
- AIDS and Cancer Virus Program, Frederick National Laboratory for Cancer Research, Frederick, Maryland, United States of America
| | - Nicholas J. Maness
- Tulane National Primate Research Center, Covington, Louisiana, United States of America
| | - Mark Marsh
- MRC Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
| | - James A. Hoxie
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
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Szojka Z, Mótyán JA, Miczi M, Mahdi M, Tőzsér J. Y44A Mutation in the Acidic Domain of HIV-2 Tat Impairs Viral Reverse Transcription and LTR-Transactivation. Int J Mol Sci 2020; 21:ijms21165907. [PMID: 32824587 PMCID: PMC7460587 DOI: 10.3390/ijms21165907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 08/10/2020] [Accepted: 08/15/2020] [Indexed: 11/28/2022] Open
Abstract
HIV transactivator protein (Tat) plays a pivotal role in viral replication through modulation of cellular transcription factors and transactivation of viral genomic transcription. The effect of HIV-1 Tat on reverse transcription has long been described in the literature, however, that of HIV-2 is understudied. Sequence homology between Tat proteins of HIV-1 and 2 is estimated to be less than 30%, and the main difference lies within their N-terminal region. Here, we describe Y44A-inactivating mutation of HIV-2 Tat, studying its effect on capsid production, reverse transcription, and the efficiency of proviral transcription. Investigation of the mutation was performed using sequence- and structure-based in silico analysis and in vitro experiments. Our results indicate that the Y44A mutant HIV-2 Tat inhibited the activity and expression of RT (reverse transcriptase), in addition to diminishing Tat-dependent LTR (long terminal repeat) transactivation. These findings highlight the functional importance of the acidic domain of HIV-2 Tat in the regulation of reverse transcription and transactivation of the integrated provirions.
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Affiliation(s)
- Zsófia Szojka
- Laboratory of Retroviral Biochemistry, Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (Z.S.); (J.A.M.); (M.M.)
- Doctoral School of Molecular Cell and Immune Biology, University of Debrecen, 4032 Debrecen, Hungary
| | - János András Mótyán
- Laboratory of Retroviral Biochemistry, Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (Z.S.); (J.A.M.); (M.M.)
| | - Márió Miczi
- Laboratory of Retroviral Biochemistry, Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (Z.S.); (J.A.M.); (M.M.)
- Doctoral School of Molecular Cell and Immune Biology, University of Debrecen, 4032 Debrecen, Hungary
| | - Mohamed Mahdi
- Laboratory of Retroviral Biochemistry, Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (Z.S.); (J.A.M.); (M.M.)
- Correspondence: (M.M.); (J.T.)
| | - József Tőzsér
- Laboratory of Retroviral Biochemistry, Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (Z.S.); (J.A.M.); (M.M.)
- Correspondence: (M.M.); (J.T.)
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3
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Williams ME, Zulu SS, Stein DJ, Joska JA, Naudé PJW. Signatures of HIV-1 subtype B and C Tat proteins and their effects in the neuropathogenesis of HIV-associated neurocognitive impairments. Neurobiol Dis 2019; 136:104701. [PMID: 31837421 DOI: 10.1016/j.nbd.2019.104701] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 11/18/2019] [Accepted: 12/08/2019] [Indexed: 11/16/2022] Open
Abstract
HIV-associated neurocognitive impairments (HANI) are a spectrum of neurological disorders due to the effects of HIV-1 on the central nervous system (CNS). The HIV-1 subtypes; HIV-1 subtype B (HIV-1B) and HIV-1 subtype C (HIV-1C) are responsible for the highest prevalence of HANI and HIV infections respectively. The HIV transactivator of transcription (Tat) protein is a major contributor to the neuropathogenesis of HIV. The effects of the Tat protein on cells of the CNS is determined by the subtype-associated amino acid sequence variations. The extent to which the sequence variation between Tat-subtypes contribute to underlying mechanisms and neurological outcomes are not clear. In this review of the literature, we discuss how amino acid variations between HIV-1B Tat (TatB) and HIV-1C Tat (TatC) proteins contribute to the potential underlying neurobiological mechanisms of HANI. Tat-C is considered to be a more effective transactivator, whereas Tat-B may exert increased neurovirulence, including neuronal apoptosis, monocyte infiltration into the brain, (neuro)inflammation, oxidative stress and blood-brain barrier damage. These findings support the premise that Tat variants from different HIV-1 subtypes may direct neurovirulence and neurological outcomes in HANI.
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Affiliation(s)
- Monray E Williams
- Department of Psychiatry and Mental Health and Neuroscience Institute, Brain Behaviour Unit, University of Cape Town, Cape Town, South Africa.
| | - Simo S Zulu
- Department of Psychiatry and Mental Health and Neuroscience Institute, Brain Behaviour Unit, University of Cape Town, Cape Town, South Africa
| | - Dan J Stein
- Department of Psychiatry and Mental Health and Neuroscience Institute, Brain Behaviour Unit, University of Cape Town, Cape Town, South Africa; SAMRC Unit on Risk and Resilience in Mental Disorders and Department of Psychiatry and Mental Health, University of Cape Town, Cape Town, South Africa
| | - John A Joska
- Division of Neuropsychiatry, Department of Psychiatry and Mental Health, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Petrus J W Naudé
- Department of Psychiatry and Mental Health and Neuroscience Institute, Brain Behaviour Unit, University of Cape Town, Cape Town, South Africa
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Hategan A, Masliah E, Nath A. HIV and Alzheimer's disease: complex interactions of HIV-Tat with amyloid β peptide and Tau protein. J Neurovirol 2019; 25:648-660. [PMID: 31016584 DOI: 10.1007/s13365-019-00736-z] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 01/15/2019] [Accepted: 02/14/2019] [Indexed: 12/21/2022]
Abstract
In patients infected with the human immunodeficiency virus (HIV), the HIV-Tat protein may be continually produced despite adequate antiretroviral therapy. As the HIV-infected population is aging, it is becoming increasingly important to understand how HIV-Tat may interact with proteins such as amyloid β and Tau which accumulate in the aging brain and eventually result in Alzheimer's disease. In this review, we examine the in vivo data from HIV-infected patients and animal models and the in vitro experiments that show how protein complexes between HIV-Tat and amyloid β occur through novel protein-protein interactions and how HIV-Tat may influence the pathways for amyloid β production, degradation, phagocytosis, and transport. HIV-Tat may also induce Tau phosphorylation through a cascade of cellular processes that lead to the formation of neurofibrillary tangles, another hallmark of Alzheimer's disease. We also identify gaps in knowledge and future directions for research. Available evidence suggests that HIV-Tat may accelerate Alzheimer-like pathology in patients with HIV infection which cannot be impacted by current antiretroviral therapy.
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Affiliation(s)
- Alina Hategan
- Section of Infections of the Nervous System, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bldg 10; Room 7C-103, 10 Center Drive, Bethesda, MD, 20892, USA
| | - Eliezer Masliah
- Division of Neuroscience, National Institute of Aging, National Institutes of Health, 7201 Wisconsin Ave, Bethesda, MD, 20892, USA
| | - Avindra Nath
- Section of Infections of the Nervous System, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bldg 10; Room 7C-103, 10 Center Drive, Bethesda, MD, 20892, USA.
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5
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van der Kuyl AC, Vink M, Zorgdrager F, Bakker M, Wymant C, Hall M, Gall A, Blanquart F, Berkhout B, Fraser C, Cornelissen M. The evolution of subtype B HIV-1 tat in the Netherlands during 1985-2012. Virus Res 2018; 250:51-64. [PMID: 29654800 DOI: 10.1016/j.virusres.2018.04.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Revised: 04/05/2018] [Accepted: 04/05/2018] [Indexed: 12/18/2022]
Abstract
For the production of viral genomic RNA, HIV-1 is dependent on an early viral protein, Tat, which is required for high-level transcription. The quantity of viral RNA detectable in blood of HIV-1 infected individuals varies dramatically, and a factor involved could be the efficiency of Tat protein variants to stimulate RNA transcription. HIV-1 virulence, measured by set-point viral load, has been observed to increase over time in the Netherlands and elsewhere. Investigation of tat gene evolution in clinical isolates could discover a role of Tat in this changing virulence. A dataset of 291 Dutch HIV-1 subtype B tat genes, derived from full-length HIV-1 genome sequences from samples obtained between 1985-2012, was used to analyse the evolution of Tat. Twenty-two patient-derived tat genes, and the control TatHXB2 were analysed for their capacity to stimulate expression of an LTR-luciferase reporter gene construct in diverse cell lines, as well as for their ability to complement a tat-defective HIV-1LAI clone. Analysis of 291 historical tat sequences from the Netherlands showed ample amino acid (aa) variation between isolates, although no specific mutations were selected for over time. Of note, however, the encoded protein varied its length over the years through the loss or gain of stop codons in the second exon. In transmission clusters, a selection against the shorter Tat86 ORF was apparent in favour of the more common Tat101 version, likely due to negative selection against Tat86 itself, although random drift, transmission bottlenecks, or linkage to other variants could also explain the observation. There was no correlation between Tat length and set-point viral load; however, the number of non-intermediate variants in our study was small. In addition, variation in the length of Tat did not significantly change its capacity to stimulate transcription. From 1985 till 2012, variation in the length of the HIV-1 subtype B tat gene is increasingly found in the Dutch epidemic. However, as Tat proteins did not differ significantly in their capacity to stimulate transcription elongation in vitro, the increased HIV-1 virulence seen in recent years could not be linked to an evolving viral Tat protein.
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Affiliation(s)
- Antoinette C van der Kuyl
- Laboratory of Experimental Virology, Department of Medical Microbiology, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ, Amsterdam, The Netherlands.
| | - Monique Vink
- Laboratory of Experimental Virology, Department of Medical Microbiology, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ, Amsterdam, The Netherlands
| | - Fokla Zorgdrager
- Laboratory of Experimental Virology, Department of Medical Microbiology, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ, Amsterdam, The Netherlands
| | - Margreet Bakker
- Laboratory of Experimental Virology, Department of Medical Microbiology, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ, Amsterdam, The Netherlands
| | - Chris Wymant
- Medical Research Council Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, W21PG, United Kingdom; Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Matthew Hall
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Astrid Gall
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA, United Kingdom
| | - François Blanquart
- Medical Research Council Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, W21PG, United Kingdom; Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Ben Berkhout
- Laboratory of Experimental Virology, Department of Medical Microbiology, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ, Amsterdam, The Netherlands
| | - Christophe Fraser
- Medical Research Council Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, W21PG, United Kingdom; Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Marion Cornelissen
- Laboratory of Experimental Virology, Department of Medical Microbiology, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ, Amsterdam, The Netherlands
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HIV Tat protein and amyloid-β peptide form multifibrillar structures that cause neurotoxicity. Nat Struct Mol Biol 2017; 24:379-386. [PMID: 28218748 PMCID: PMC5383535 DOI: 10.1038/nsmb.3379] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 01/16/2017] [Indexed: 11/08/2022]
Abstract
Deposition of amyloid-β plaques is increased in the brains of HIV-infected individuals, and the HIV transactivator of transcription (Tat) protein affects amyloidogenesis through several indirect mechanisms. Here, we investigated direct interactions between Tat and amyloid-β peptide. Our in vitro studies showed that in the presence of Tat, uniform amyloid fibrils become double twisted fibrils and further form populations of thick unstructured filaments and aggregates. Specifically, Tat binding to the exterior surfaces of the Aβ fibrils increases β-sheet formation and lateral aggregation into thick multifibrillar structures, thus producing fibers with increased rigidity and mechanical resistance. Furthermore, Tat and Aβ aggregates in complex synergistically induced neurotoxicity both in vitro and in animal models. Increased rigidity and mechanical resistance of the amyloid-β-Tat complexes coupled with stronger adhesion due to the presence of Tat in the fibrils may account for increased damage, potentially through pore formation in membranes.
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Kamori D, Ueno T. HIV-1 Tat and Viral Latency: What We Can Learn from Naturally Occurring Sequence Variations. Front Microbiol 2017; 8:80. [PMID: 28194140 PMCID: PMC5276809 DOI: 10.3389/fmicb.2017.00080] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 01/11/2017] [Indexed: 01/25/2023] Open
Abstract
Despite the effective use of antiretroviral therapy, the remainder of a latently HIV-1-infected reservoir mainly in the resting memory CD4+ T lymphocyte subset has provided a great setback toward viral eradication. While host transcriptional silencing machinery is thought to play a dominant role in HIV-1 latency, HIV-1 protein such as Tat, may affect both the establishment and the reversal of latency. Indeed, mutational studies have demonstrated that insufficient Tat transactivation activity can result in impaired transcription of viral genes and the establishment of latency in cell culture experiments. Because Tat protein is one of highly variable proteins within HIV-1 proteome, it is conceivable that naturally occurring Tat mutations may differentially modulate Tat functions, thereby influencing the establishment and/or the reversal of viral latency in vivo. In this mini review, we summarize the recent findings of Tat naturally occurring polymorphisms associating with host immune responses and we highlight the implication of Tat sequence variations in relation to HIV latency.
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Affiliation(s)
- Doreen Kamori
- Center for AIDS Research, Kumamoto University Kumamoto, Japan
| | - Takamasa Ueno
- Center for AIDS Research, Kumamoto UniversityKumamoto, Japan; International Research Center for Medical Sciences, Kumamoto UniversityKumamoto, Japan
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Es-Salah-Lamoureux Z, Jouni M, Malak OA, Belbachir N, Al Sayed ZR, Gandon-Renard M, Lamirault G, Gauthier C, Baró I, Charpentier F, Zibara K, Lemarchand P, Beaumelle B, Gaborit N, Loussouarn G. HIV-Tat induces a decrease in I Kr and I Ks via reduction in phosphatidylinositol-(4,5)-bisphosphate availability. J Mol Cell Cardiol 2016; 99:1-13. [DOI: 10.1016/j.yjmcc.2016.08.022] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Revised: 08/23/2016] [Accepted: 08/29/2016] [Indexed: 02/07/2023]
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Zhao X, Qian L, Zhou D, Qi D, Liu C, Kong X. Stability of HIV-1 subtype B and C Tat is associated with variation in the carboxyl-terminal region. Virol Sin 2016; 31:199-206. [PMID: 27007880 DOI: 10.1007/s12250-016-3681-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Accepted: 03/01/2016] [Indexed: 12/14/2022] Open
Abstract
The multifunctional trans-activator Tat is an essential regulatory protein for HIV-1 replication and is characterized by high sequence diversity. Numerous experimental studies have examined Tat in HIV-1 subtype B, but research on subtype C Tat is lacking, despite the high prevalence of infections caused by subtype C worldwide. We hypothesized that amino acid differences contribute to functional differences among Tat proteins. In the present study, we found that subtype B NL4-3 Tat and subtype C isolate HIV1084i Tat exhibited differences in stability by overexpressing the fusion protein Tat-Flag. In addition, 1084i Tat can activate LTR and NF-κB more efficiently than NL4-3 Tat. In analyses of the activities of the truncated forms of Tat, we found that the carboxyl-terminal region of Tat regulates its stability and transactivity. According to our results, we speculated that the differences in stability between B-Tat and C-Tat result in differences in transactivation ability.
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Affiliation(s)
- Xuechao Zhao
- Laboratory of Medical Molecular Virology, School of Medicine, Nankai University, Tianjin, 300071, China
| | - Lingyu Qian
- Laboratory of Medical Molecular Virology, School of Medicine, Nankai University, Tianjin, 300071, China
| | - Deyu Zhou
- Laboratory of Medical Molecular Virology, School of Medicine, Nankai University, Tianjin, 300071, China
| | - Di Qi
- Laboratory of Medical Molecular Virology, School of Medicine, Nankai University, Tianjin, 300071, China
| | - Chang Liu
- Laboratory of Medical Molecular Virology, School of Medicine, Nankai University, Tianjin, 300071, China
| | - Xiaohong Kong
- Laboratory of Medical Molecular Virology, School of Medicine, Nankai University, Tianjin, 300071, China.
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To V, Dzananovic E, McKenna SA, O’Neil J. The Dynamic Landscape of the Full-Length HIV-1 Transactivator of Transcription. Biochemistry 2016; 55:1314-25. [DOI: 10.1021/acs.biochem.5b01178] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Vu To
- Department of Chemistry, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada
| | - Edis Dzananovic
- Department of Chemistry, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada
| | - Sean A. McKenna
- Department of Chemistry, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada
| | - Joe O’Neil
- Department of Chemistry, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada
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11
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Roy CN, Khandaker I, Furuse Y, Oshitani H. Molecular characterization of full-length Tat in HIV-1 subtypes B and C. Bioinformation 2015; 11:151-60. [PMID: 25914449 PMCID: PMC4403036 DOI: 10.6026/97320630011151] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 03/02/2015] [Indexed: 12/13/2022] Open
Abstract
HIV-1Tat (trans-acting activator of transcription) plays essential roles in the replication through viral mRNA and genome transcription from the HIV-1 LTR promoter. However, Tat undergoes continuous amino acid substitutions. As a consequence, the virus escapes from host immunity indicating that genetic diversity of Tat protein in major HIV-1 subtypes is required to be continuously monitored. We analyzed available full-length HIV-1 sequences of subtypes B (n=493) and C (n=280) strains circulating worldwide. We observed 81% and 84% nucleotide sequence identities of HIV-1 Tat for subtypes B and C, respectively. Based on phylogenetic and mutation analyses, global diversity of subtype B was apparently higher compared to that of subtype C. Positively selected sites, such as positions Ser68 and Ser70 in both subtypes, were located in the Tat-transactivation responsive RNA (TAR) interaction domain. We also found positively selected sites in exon 2, such as positions Ser75, Pro77, Asp80, Pro81 and Ser87 for both subtypes. Our study provides useful information on the full-length HIV-1 Tat sequences in globally circulating strains.
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Affiliation(s)
- Chandra Nath Roy
- Department of Virology, Tohoku University Graduate School of Medicine, 2-1 Seiryomachi, Aoba-ku, Sendai city, Miyagi, Japan-9808575
| | - Irona Khandaker
- Department of Virology, Tohoku University Graduate School of Medicine, 2-1 Seiryomachi, Aoba-ku, Sendai city, Miyagi, Japan-9808575
| | - Yuki Furuse
- Department of Virology, Tohoku University Graduate School of Medicine, 2-1 Seiryomachi, Aoba-ku, Sendai city, Miyagi, Japan-9808575
| | - Hitoshi Oshitani
- Department of Virology, Tohoku University Graduate School of Medicine, 2-1 Seiryomachi, Aoba-ku, Sendai city, Miyagi, Japan-9808575
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12
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Zhang L, Qin J, Li Y, Wang J, He Q, Zhou J, Liu M, Li D. Modulation of the stability and activities of HIV-1 Tat by its ubiquitination and carboxyl-terminal region. Cell Biosci 2014; 4:61. [PMID: 25328666 PMCID: PMC4201738 DOI: 10.1186/2045-3701-4-61] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Accepted: 09/27/2014] [Indexed: 11/28/2022] Open
Abstract
Background The transactivator of transcription (Tat) protein of human immunodeficiency virus type 1 (HIV-1) is known to undergo ubiquitination. However, the roles of ubiquitination in regulating Tat stability and activities are unclear. In addition, although the 72- and 86-residue forms are commonly used for in vitro studies, the 101-residue form is predominant in the clinical isolates of HIV-1. The influence of the carboxyl-terminal region of Tat on its functions remains unclear. Results In this study, we find that Tat undergoes lysine 48-linked ubiquitination and is targeted to proteasome-dependent degradation. Expression of various ubiquitin mutants modulates Tat activities, including the transactivation of transcription, induction of apoptosis, interaction with tubulin, and stabilization of microtubules. Moreover, the 72-, 86- and 101-residue forms of Tat also exhibit different stability and aforementioned activities. Conclusions Our findings demonstrate that the ubiquitination and carboxyl-terminal region of Tat are critical determinants of its stability and activities.
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Affiliation(s)
- Linlin Zhang
- State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin, 300071 China
| | - Juan Qin
- State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin, 300071 China
| | - Yuanyuan Li
- State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin, 300071 China
| | - Jian Wang
- State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin, 300071 China
| | - Qianqian He
- State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin, 300071 China
| | - Jun Zhou
- State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin, 300071 China
| | - Min Liu
- State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin, 300071 China
| | - Dengwen Li
- State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin, 300071 China
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Moran LM, Fitting S, Booze RM, Webb KM, Mactutus CF. Neonatal intrahippocampal HIV-1 protein Tat(1-86) injection: neurobehavioral alterations in the absence of increased inflammatory cytokine activation. Int J Dev Neurosci 2014; 38:195-203. [PMID: 25285887 DOI: 10.1016/j.ijdevneu.2014.09.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Revised: 09/11/2014] [Accepted: 09/12/2014] [Indexed: 01/05/2023] Open
Abstract
Pediatric AIDS caused by human immunodeficiency virus type 1 (HIV-1) remains one of the leading worldwide causes of childhood morbidity and mortality. HIV-1 proteins, such as Tat and gp120, are believed to play a crucial role in the neurotoxicity of pediatric HIV-1 infection. Detrimental effects on development, behavior, and neuroanatomy follow neonatal exposure to the HIV-1 viral toxins Tat1-72 and gp120. The present study investigated the neurobehavioral effects induced by the HIV-1 neurotoxic protein Tat1-86, which encodes the first and second exons of the Tat protein. In addition, the potential effects of HIV-1 toxic proteins Tat1-86 and gp120 on inflammatory pathways were examined in neonatal brains. Vehicle, 25 μg Tat1-86 or 100 ng gp120 was injected into the hippocampus of male Sprague-Dawley pups on postnatal day 1 (PD1). Tat1-86 induced developmental neurotoxic effects, as witnessed by delays in eye opening, delays in early reflex development and alterations in prepulse inhibition (PPI) and between-session habituation of locomotor activity. Overall, the neurotoxic profile of Tat1-86 appeared more profound in the developing nervous system in vivo relative to that seen with the first exon encoded Tat1-72 (Fitting et al., 2008b), as noted on measures of eye opening, righting reflex, and PPI. Neither the direct PD1 CNS injection of the viral HIV-1 protein variant Tat1-86, nor the HIV-1 envelope protein gp120, at doses sufficient to induce neurotoxicity, necessarily induced significant expression of the inflammatory cytokine IL-1β or inflammatory factors NF-κβ and I-κβ. The findings agree well with clinical observations that indicate delays in developmental milestones of pediatric HIV-1 patients, and suggest that activation of inflammatory pathways is not an obligatory response to viral protein-induced neurotoxicity that is detectable with behavioral assessments. Moreover, the amino acids encoded by the second tat exon may have unique actions on the developing hippocampus.
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Affiliation(s)
- Landhing M Moran
- University of South Carolina, Behavioral Neuroscience Program, Department of Psychology, Columbia, SC 29208, USA
| | - Sylvia Fitting
- University of South Carolina, Behavioral Neuroscience Program, Department of Psychology, Columbia, SC 29208, USA
| | - Rosemarie M Booze
- University of South Carolina, Behavioral Neuroscience Program, Department of Psychology, Columbia, SC 29208, USA
| | - Katy M Webb
- University of South Carolina, Behavioral Neuroscience Program, Department of Psychology, Columbia, SC 29208, USA
| | - Charles F Mactutus
- University of South Carolina, Behavioral Neuroscience Program, Department of Psychology, Columbia, SC 29208, USA.
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Kukkonen S, Martinez-Viedma MDP, Kim N, Manrique M, Aldovini A. HIV-1 Tat second exon limits the extent of Tat-mediated modulation of interferon-stimulated genes in antigen presenting cells. Retrovirology 2014; 11:30. [PMID: 24742347 PMCID: PMC4036831 DOI: 10.1186/1742-4690-11-30] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 03/27/2014] [Indexed: 12/14/2022] Open
Abstract
Background We have shown that HIV-1 Tat interaction with MAP2K3, MAP2K6, and IRF7 promoters is key to IFN-stimulated genes (ISG) activation in immature dendritic cells and macrophages. Results We evaluated how Tat alleles and mutants differ in cellular gene modulation of immature dendritic cells and monocyte-derived macrophages and what similarities this modulation has with that induced by interferons. The tested alleles and mutants modulated to different degrees ISG, without concomitant induction of interferons. The first exon TatSF21-72 and the minimal transactivator TatSF21-58, all modulated genes to a significantly greater extent than full-length wild type, two-exon Tat, indicating that Tat second exon is critical in reducing the innate response triggered by HIV-1 in these cells. Mutants with reduced LTR transactivation had a substantially reduced effect on host gene expression modulation than wild type TatSF2. However, the more potent LTR transactivator TatSF2A58T modulated ISG expression to a lower degree compared to TatSF2. A cellular gene modulation similar to that induced by Tat and Tat mutants in immature dendritic cells could be observed in monocyte-derived macrophages, with the most significant pathways affected by Tat being the same in both cell types. Tat expression in cells deleted of the type I IFN locus or receptor resulted in a gene modulation pattern similar to that induced in primary immature dendritic cells and monocyte-derived macrophages, excluding the involvement of type I IFNs in Tat-mediated gene modulation. ISG activation depends on Tat interaction with MAP2K3, MAP2K6, and IRF7 promoters and a single exon Tat protein more strongly modulated the luciferase activity mediated by MAP2K3, MAP2K6, and IRF7 promoter sequences located 5′ of the RNA start site than the wild type two-exon Tat, while a cysteine and lysine Tat mutants, reduced in LTR transactivation, had negligible effects on these promoters. Chemical inhibition of CDK9 or Sp1 decreased Tat activation of MAP2K3-, MAP2K6-, and IRF7-mediated luciferase transcription. Conclusions Taken together, these data indicate that the second exon of Tat is critical to the containment of the innate response stimulated by Tat in antigen presenting cells and support a role for Tat in stimulating cellular transcription via its interaction with transcription factors present at promoters.
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Affiliation(s)
| | | | | | | | - Anna Aldovini
- Department of Pediatrics, Harvard Medical School, Department of Medicine, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA.
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Identification of a cluster of HIV-1 controllers infected with low replicating viruses. PLoS One 2013; 8:e77663. [PMID: 24204910 PMCID: PMC3813686 DOI: 10.1371/journal.pone.0077663] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Accepted: 09/12/2013] [Indexed: 11/19/2022] Open
Abstract
Long term non-progressor patients (LTNPs) are characterized by the natural control of HIV-1 infection. This control is related to host genetic, immunological and virological factors. In this work, phylogenetic analysis of the proviral nucleotide sequences in env gene from a Spanish HIV-1 LTNPs cohort identified a cluster of 6 HIV-1 controllers infected with closely-related viruses. The patients of the cluster showed common clinical and epidemiological features: drug user practices, infection in the same city (Madrid, Spain) and at the same time (late 70's-early 80's). All cluster patients displayed distinct host alleles associated with HIV control. Analysis of the virus envelope nucleotide sequences showed ancestral characteristic, lack of evolution and presence of rare amino-acids. Biological characterization of recombinant viruses with the envelope proteins from the cluster viruses showed very low replicative capacity in TZMbl and U87-CD4/CCR5 cells. The lack of clinical progression in the viral cluster patients with distinct combinations of protective host genotypes, but infected by low replicating viruses, indicate the important role of the virus in the non-progressor phenotype in these patients.
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tat Exon 1 exhibits functional diversity during HIV-1 subtype C primary infection. J Virol 2013; 87:5732-45. [PMID: 23487450 DOI: 10.1128/jvi.03297-12] [Citation(s) in RCA: 11] [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 (HIV-1) Tat is a mediator of viral transcription and is involved in the control of virus replication. However, associations between HIV-1 Tat diversity and functional effects during primary HIV-1 infection are still unclear. We estimated selection pressures in tat exon 1 using the mixed-effects model of evolution with 672 viral sequences generated from 20 patients infected with HIV-1 subtype C (HIV-1C) over 500 days postseroconversion. tat exon 1 residues 3, 4, 21, 24, 29, 39, and 68 were under positive selection, and we established that specific amino acid signature patterns were apparent in primary HIV-1C infection compared with chronic infection. We assessed the impact of these mutations on long terminal repeat (LTR) activity and found that Tat activity was negatively affected by the Ala(21) substitution identified in 13/20 (65%) of patients, which reduced LTR activity by 88% (± 1%) (P < 0.001). The greatest increase in Tat activity was seen with the Gln(35)/Lys(39) double mutant that resulted in an additional 49% (± 14%) production of LTR-driven luciferase (P = 0.012). There was a moderate positive correlation between Tat-mediated LTR activity and HIV-1 RNA in plasma (P = 0.026; r = 0.400) after 180 days postseroconversion that was reduced by 500 days postseroconversion (P = 0.043; r = 0.266). Although Tat activation of the LTR is not a strong predictor of these clinical variables, there are significant linear relationships between Tat transactivation and patients' plasma viral loads and CD4 counts, highlighting the complex interplay between Tat mutations in early HIV-1C infection.
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López-Huertas MR, Mateos E, Sánchez Del Cojo M, Gómez-Esquer F, Díaz-Gil G, Rodríguez-Mora S, López JA, Calvo E, López-Campos G, Alcamí J, Coiras M. The presence of HIV-1 Tat protein second exon delays fas protein-mediated apoptosis in CD4+ T lymphocytes: a potential mechanism for persistent viral production. J Biol Chem 2013; 288:7626-7644. [PMID: 23364796 DOI: 10.1074/jbc.m112.408294] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
HIV-1 replication is efficiently controlled by the regulator protein Tat (101 amino acids) and codified by two exons, although the first exon (1-72 amino acids) is sufficient for this process. Tat can be released to the extracellular medium, acting as a soluble pro-apoptotic factor in neighboring cells. However, HIV-1-infected CD4(+) T lymphocytes show a higher resistance to apoptosis. We observed that the intracellular expression of Tat delayed FasL-mediated apoptosis in both peripheral blood lymphocytes and Jurkat cells, as it is an essential pathway to control T cell homeostasis during immune activation. Jurkat-Tat cells showed impairment in the activation of caspase-8, deficient release of mitochondrial cytochrome c, and delayed activation of both caspase-9 and -3. This protection was due to a profound deregulation of proteins that stabilized the mitochondrial membrane integrity, such as heat shock proteins, prohibitin, or nucleophosmin, as well as to the up-regulation of NF-κB-dependent anti-apoptotic proteins, such as BCL2, c-FLIPS, XIAP, and C-IAP2. These effects were observed in Jurkat expressing full-length Tat (Jurkat-Tat101) but not in Jurkat expressing the first exon of Tat (Jurkat-Tat72), proving that the second exon, and particularly the NF-κB-related motif ESKKKVE, was necessary for Tat-mediated protection against FasL apoptosis. Accordingly, the protection exerted by Tat was independent of its function as a regulator of both viral transcription and elongation. Moreover, these data proved that HIV-1 could have developed strategies to delay FasL-mediated apoptosis in infected CD4(+) T lymphocytes through the expression of Tat, thus favoring the persistent replication of HIV-1 in infected T cells.
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Affiliation(s)
- María Rosa López-Huertas
- Unidad de Inmunopatología del SIDA, Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Majadahonda, Spain
| | - Elena Mateos
- Unidad de Inmunopatología del SIDA, Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Majadahonda, Spain
| | - María Sánchez Del Cojo
- Unidad de Inmunopatología del SIDA, Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Majadahonda, Spain
| | - Francisco Gómez-Esquer
- Facultad de Ciencias de la Salud, Universidad Rey Juan Carlos, 28922 Alcorcón, Madrid, Spain
| | - Gema Díaz-Gil
- Facultad de Ciencias de la Salud, Universidad Rey Juan Carlos, 28922 Alcorcón, Madrid, Spain
| | - Sara Rodríguez-Mora
- Unidad de Inmunopatología del SIDA, Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Majadahonda, Spain
| | - Juan Antonio López
- Unidad de Proteómica, Centro Nacional de Investigaciones Cardiovasculares, 28029 Madrid, Spain
| | - Enrique Calvo
- Unidad de Proteómica, Centro Nacional de Investigaciones Cardiovasculares, 28029 Madrid, Spain
| | - Guillermo López-Campos
- Health and Biomedical Informatics Research Unit, Melbourne Medical School, 3010 Melbourne, Australia
| | - José Alcamí
- Unidad de Inmunopatología del SIDA, Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Majadahonda, Spain
| | - Mayte Coiras
- Unidad de Inmunopatología del SIDA, Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Majadahonda, Spain.
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Abstract
PURPOSE OF REVIEW Much of the current HIV-1 vaccine research focuses on harnessing the cytotoxic T-lymphocyte arm of the immune response. However, HIV-1 appears to have an unerring ability to evade cytotoxic T-lymphocyte responses, through the process of escape mutation, and thus the potential benefit of a cytotoxic T-lymphocyte-based vaccine remains uncertain. This review focuses on several recent studies that question whether escape mutation is always detrimental to the host, and may provide new hope for the success of a cytotoxic T-lymphocyte-based vaccine against HIV. RECENT FINDINGS Several recent studies, in both natural HIV-1 infection and the SIV model, have identified examples of cytotoxic T-lymphocyte escape mutants that revert on transmission to individuals lacking the selecting major histocompatibility complex alleles. The obvious implication of these data is that some cytotoxic T-lymphocyte responses can only be evaded through escape mutations that actually reduce the replicative fitness of the virus. In addition, a recent vaccine study in macaques found that the control of immunodeficiency virus to undetectable levels was only achieved in animals that were able to force the virus to make such detrimental escape mutations. These data raise the intriguing possibility that, rather than undermining cytotoxic T-lymphocyte vaccines, escape mutation may be one of the keys to their success. SUMMARY Clearly, not all escape mutations help to control viral replication. We discuss how these new data may assist in the struggle to develop a successful cytotoxic T-lymphocyte-based HIV vaccine, and what they tell us about the responses such a vaccine should aim to elicit.
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19
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Impact of Tat Genetic Variation on HIV-1 Disease. Adv Virol 2012; 2012:123605. [PMID: 22899925 PMCID: PMC3414192 DOI: 10.1155/2012/123605] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Accepted: 05/14/2012] [Indexed: 01/08/2023] Open
Abstract
The human immunodeficiency virus type 1 (HIV-1) promoter or long-terminal repeat (LTR) regulates viral gene expression by interacting with multiple viral and host factors. The viral transactivator protein Tat plays an important role in transcriptional activation of HIV-1 gene expression. Functional domains of Tat and its interaction with transactivation response element RNA and cellular transcription factors have been examined. Genetic variation within tat of different HIV-1 subtypes has been shown to affect the interaction of the viral transactivator with cellular and/or viral proteins, influencing the overall level of transcriptional activation as well as its action as a neurotoxic protein. Consequently, the genetic variability within tat may impact the molecular architecture of functional domains of the Tat protein that may impact HIV pathogenesis and disease. Tat as a therapeutic target for anti-HIV drugs has also been discussed.
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20
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Liao W, Tan G, Zhu Z, Chen Q, Lou Z, Dong X, Zhang W, Pan W, Chai Y. HIV-1 Tat induces biochemical changes in the serum of mice. Virology 2012; 422:288-96. [DOI: 10.1016/j.virol.2011.11.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2011] [Revised: 09/22/2011] [Accepted: 11/06/2011] [Indexed: 10/15/2022]
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21
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Strazza M, Pirrone V, Wigdahl B, Nonnemacher MR. Breaking down the barrier: the effects of HIV-1 on the blood-brain barrier. Brain Res 2011; 1399:96-115. [PMID: 21641584 DOI: 10.1016/j.brainres.2011.05.015] [Citation(s) in RCA: 150] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Revised: 05/06/2011] [Accepted: 05/07/2011] [Indexed: 01/13/2023]
Abstract
Human immunodeficiency virus type 1 (HIV-1) primarily infects CD4(+) T cells and cells of the monocyte-macrophage lineage, resulting in immunodeficiency in an infected patient. Along with this immune deficiency, HIV-1 has been linked to a number of neurological symptoms in the absence of opportunistic infections or other co-morbidities, suggesting that HIV-1 is able to cross the blood-brain barrier (BBB), enter the central nervous system (CNS), and cause neurocognitive impairment. HIV-1-infected monocyte-macrophages traverse the BBB and enter the CNS throughout the course of HIV-1 disease. Once in the brain, both free virus and virus-infected cells are able to infect neighboring resident microglia and astrocytes and possibly other cell types. HIV-1-infected cells in both the periphery and the CNS give rise to elevated levels of viral proteins, including gp120, Tat, and Nef, and of host inflammatory mediators such as cytokines and chemokines. It has been shown that the viral proteins may act alone or in concert with host cytokines and chemokines, affecting the integrity of the BBB. The pathological end point of these interactions may facilitate a positive feedback loop resulting in increased penetration of HIV into the CNS. It is proposed in this review that the dysregulation of the BBB during and after neuroinvasion is a critical component of the neuropathogenic process and that dysregulation of this protective barrier is caused by a combination of viral and host factors including secreted viral proteins, components of the inflammatory process, the aging process, therapeutics, and drug or alcohol abuse.
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Affiliation(s)
- Marianne Strazza
- Department of Microbiology and Immunology, and Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, Philadelphia, PA 19102, USA
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22
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McQueen P, Donald LJ, Vo TN, Nguyen DH, Griffiths H, Shojania S, Standing KG, O'Neil JD. Tat peptide-calmodulin binding studies and bioinformatics of HIV-1 protein-calmodulin interactions. Proteins 2011; 79:2233-46. [DOI: 10.1002/prot.23048] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Revised: 03/18/2011] [Accepted: 03/22/2011] [Indexed: 01/08/2023]
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23
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Shojania S, Henry GD, Chen VC, Vo TN, Perreault H, O’Neil JD. High yield expression and purification of HIV-1 Tat1−72 for structural studies. J Virol Methods 2010; 164:35-42. [DOI: 10.1016/j.jviromet.2009.11.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2009] [Revised: 11/17/2009] [Accepted: 11/17/2009] [Indexed: 12/11/2022]
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24
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López-Huertas MR, Callejas S, Abia D, Mateos E, Dopazo A, Alcamí J, Coiras M. Modifications in host cell cytoskeleton structure and function mediated by intracellular HIV-1 Tat protein are greatly dependent on the second coding exon. Nucleic Acids Res 2010; 38:3287-307. [PMID: 20139419 PMCID: PMC2879518 DOI: 10.1093/nar/gkq037] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The human immunodeficiency virus type 1 (HIV-1) regulator Tat is essential for viral replication because it achieves complete elongation of viral transcripts. Tat can be released to the extracellular space and taken up by adjacent cells, exerting profound cytoskeleton rearrangements that lead to apoptosis. In contrast, intracellular Tat has been described as protector from apoptosis. Tat gene is composed by two coding exons that yield a protein of 101 amino acids (aa). First exon (1–72aa) is sufficient for viral transcript elongation and second exon (73–101 aa) appears to contribute to non-transcriptional functions. We observed that Jurkat cells stably expressing intracellular Tat101 showed gene expression deregulation 4-fold higher than cells expressing Tat72. Functional experiments were performed to evaluate the effect of this deregulation. First, NF-κB-, NF-AT- and Sp1-dependent transcriptional activities were greatly enhanced in Jurkat-Tat101, whereas Tat72 induced milder but efficient activation. Second, cytoskeleton-related functions as cell morphology, proliferation, chemotaxis, polarization and actin polymerization were deeply altered in Jurkat-Tat101, but not in Jurkat-Tat72. Finally, expression of several cell surface receptors was dramatically impaired by intracellular Tat101 but not by Tat72. Consequently, these modifications were greatly dependent on Tat second exon and they could be related to the anergy observed in HIV-1-infected T cells.
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Affiliation(s)
- M R López-Huertas
- AIDS Immunopathology Unit, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Madrid, Spain
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25
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Caputo A, Gavioli R, Bellino S, Longo O, Tripiciano A, Francavilla V, Sgadari C, Paniccia G, Titti F, Cafaro A, Ferrantelli F, Monini P, Ensoli F, Ensoli B. HIV-1 Tat-based vaccines: an overview and perspectives in the field of HIV/AIDS vaccine development. Int Rev Immunol 2009; 28:285-334. [PMID: 19811313 DOI: 10.1080/08830180903013026] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
The HIV epidemic continues to represent one of the major problems worldwide, particularly in the Asia and Sub-Saharan regions of the world, with social and economical devastating effects. Although antiretroviral drugs have had a dramatically beneficial impact on HIV-infected individuals that have access to treatment, it has had a negligible impact on the global epidemic. Hence, the inexorable spreading of the HIV pandemic and the increasing deaths from AIDS, especially in developing countries, underscore the urgency for an effective vaccine against HIV/AIDS. However, the generation of such a vaccine has turned out to be extremely challenging. Here we provide an overview on the rationale for the use of non-structural HIV proteins, such as the Tat protein, alone or in combination with other HIV early and late structural HIV antigens, as novel, promising preventative and therapeutic HIV/AIDS vaccine strategies.
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Affiliation(s)
- Antonella Caputo
- Department of Histology, Microbiology and Medical Biotechnology, University of Padova, Padova, Italy
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26
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Turbant S, Martinon F, Moine G, Le Grand R, Léonetti M. Cynomolgus macaques immunized with two HIV-1 Tat stabilized proteins raise strong and long-lasting immune responses with a pattern of Th1/Th2 response differing from that in mice. Vaccine 2009; 27:5349-56. [DOI: 10.1016/j.vaccine.2009.06.083] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2009] [Revised: 06/15/2009] [Accepted: 06/24/2009] [Indexed: 10/20/2022]
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Campbell GR, Loret EP. What does the structure-function relationship of the HIV-1 Tat protein teach us about developing an AIDS vaccine? Retrovirology 2009; 6:50. [PMID: 19467159 PMCID: PMC2693501 DOI: 10.1186/1742-4690-6-50] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2009] [Accepted: 05/25/2009] [Indexed: 11/03/2022] Open
Abstract
The human immunodeficiency virus type 1 (HIV-1) trans-activator of transcription protein Tat is an important factor in viral pathogenesis. In addition to its function as the key trans-activator of viral transcription, Tat is also secreted by the infected cell and taken up by neighboring cells where it has an effect both on infected and uninfected cells. In this review we will focus on the relationship between the structure of the Tat protein and its function as a secreted factor. To this end we will summarize some of the exogenous functions of Tat that have been implicated in HIV-1 pathogenesis and the impact of structural variations and viral subtype variants of Tat on those functions. Finally, since in some patients the presence of Tat-specific antibodies or CTL frequencies are associated with slow or non-progression to AIDS, we will also discuss the role of Tat as a potential vaccine candidate, the advances made in this field, and the importance of using a Tat protein capable of eliciting a protective or therapeutic immune response to viral challenge.
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Affiliation(s)
- Grant R Campbell
- Department of Pediatrics, Division of Infectious Diseases, University of California San Diego, La Jolla, California 92093-0672, USA.
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28
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Caputo A, Gavioli R, Bellino S, Longo O, Tripiciano A, Francavilla V, Sgadari C, Paniccia G, Titti F, Cafaro A, Ferrantelli F, Monini P, Ensoli F, Ensoli B. HIV-1 Tat-Based Vaccines: An Overview and Perspectives in the Field of HIV/AIDS Vaccine Development. Int Rev Immunol 2009. [DOI: 10.1080/08830180903013026 10.1080/08830180903013026] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
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29
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Houzet L, Yeung ML, de Lame V, Desai D, Smith SM, Jeang KT. MicroRNA profile changes in human immunodeficiency virus type 1 (HIV-1) seropositive individuals. Retrovirology 2008; 5:118. [PMID: 19114009 PMCID: PMC2644721 DOI: 10.1186/1742-4690-5-118] [Citation(s) in RCA: 174] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2008] [Accepted: 12/29/2008] [Indexed: 12/12/2022] Open
Abstract
MicroRNAs (miRNAs) play diverse roles in regulating cellular and developmental functions. We have profiled the miRNA expression in peripheral blood mononuclear cells from 36 HIV-1 seropositive individuals and 12 normal controls. The HIV-1-positive individuals were categorized operationally into four classes based on their CD4+ T-cell counts and their viral loads. We report that specific miRNA signatures can be observed for each of the four classes.
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Affiliation(s)
- Laurent Houzet
- Molecular Virology Section, Laboratory of Molecular Microbiology National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD 20892, USA.
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Passiatore G, Rom S, Eletto D, Peruzzi F. HIV-1 Tat C-terminus is cleaved by calpain 1: implication for Tat-mediated neurotoxicity. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1793:378-87. [PMID: 19022302 DOI: 10.1016/j.bbamcr.2008.10.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2008] [Revised: 09/24/2008] [Accepted: 10/14/2008] [Indexed: 01/15/2023]
Abstract
HIV-Encephalopathy (HIVE) is a common neurological disorder associated with HIV-1 infection and AIDS. The activity of the HIV trans-activating protein Tat is thought to contribute to neuronal pathogenesis. While Tat proteins from primary virus isolates consist of 101 or more amino acids, 72 and 86 amino acids forms of Tat are commonly used for in vitro studies. Although Tat72 contains the minimal domain required for viral replication, other activities of Tat appear to vary according to its length, sub-cellular localization, cell type and the stage of cellular differentiation. In this study, we investigated the stability of intracellular Tat101 during proliferation and differentiation of neuronal cells in culture. We have utilized rat neuronal progenitors as a model of neuronal cell proliferation and differentiation, as well as rat primary cortical neurons as a model of fully differentiated cells. Our results indicate that, upon internalization, Tat101 was degraded more rapidly in proliferating cells than in cells which either underwent neuronal differentiation or were fully differentiated. Intracellular degradation of Tat was prevented by the calpain 1 inhibitor, ALLN, in both proliferating and differentiated cells. Inhibition of calpain 1 by calpastatin peptide also prevented Tat cleavage. In vitro calpain digestion and mass spectrometry analysis further demonstrated that the sequence of Tat sensitive to calpain cleavage was located in the C-terminus of this viral protein, between amino acids 68 and 69. Moreover, cleavage of Tat101 by calpain 1 increased neurotoxic effect of this viral protein and presence of the calpain inhibitor protected neuronal cells from Tat-mediated toxicity.
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Affiliation(s)
- Giovanni Passiatore
- Department of Neuroscience and Center for Neurovirology, Temple University School of Medicine, 1900 North 12th Street, Philadelphia, Pennsylvania 19122, USA
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Watkins JD, Campbell GR, Halimi H, Loret EP. Homonuclear 1H NMR and circular dichroism study of the HIV-1 Tat Eli variant. Retrovirology 2008; 5:83. [PMID: 18808674 PMCID: PMC2557015 DOI: 10.1186/1742-4690-5-83] [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: 04/30/2008] [Accepted: 09/22/2008] [Indexed: 11/30/2022] Open
Abstract
Background The HIV-1 Tat protein is a promising target to develop AIDS therapies, particularly vaccines, due to its extracellular role that protects HIV-1-infected cells from the immune system. Tat exists in two different lengths, 86 or 87 residues and 99 or 101 residues, with the long form being predominant in clinical isolates. We report here a structural study of the 99 residue Tat Eli variant using 2D liquid-state NMR, molecular modeling and circular dichroism. Results Tat Eli was obtained from solid-phase peptide synthesis and the purified protein was proven biologically active in a trans-activation assay. Circular dichroism spectra at different temperatures up to 70°C showed that Tat Eli is not a random coil at 20°C. Homonuclear 1H NMR spectra allowed us to identify 1639 NMR distance constraints out of which 264 were interresidual. Molecular modeling satisfying at least 1474 NMR constraints revealed the same folding for different model structures. The Tat Eli model has a core region composed of a part of the N-terminus including the highly conserved Trp 11. The extra residues in the Tat Eli C-terminus protrude from a groove between the basic region and the cysteine-rich region and are well exposed to the solvent. Conclusion We show that active Tat variants share a similar folding pattern whatever their size, but mutations induce local structural changes.
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Affiliation(s)
- Jennifer D Watkins
- Faculté de Pharmacie, Unité Mixte de Recherche Université de la Méditerranée/INSERM U911, Université de la Méditerranée, Marseille, France.
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Lecoq A, Moine G, Bellanger L, Drevet P, Thai R, Lajeunesse E, Ménez A, Léonetti M. Increasing the humoral immunogenic properties of the HIV-1 Tat protein using a ligand-stabilizing strategy. Vaccine 2008; 26:2615-26. [PMID: 18394763 DOI: 10.1016/j.vaccine.2008.02.057] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2007] [Revised: 02/19/2008] [Accepted: 02/27/2008] [Indexed: 10/22/2022]
Abstract
Tat is regarded as an attractive target for the development of an AIDS vaccine. However, works suggest that Tat is a poorly immunogenic protein and therefore we attempted to increase its immunogenic potency. As we observed that Tat is highly sensitive to enzymatic degradation in vitro we tried to make it less susceptible to proteolysis using ligands. We complexed Tat101 with various sulfated sugars and observed that some of these ligands made the protein more resistant to proteolysis and more immunogenic. In a more thorough study, we observed that a low-molecular-weight heparin fragment, called Hep6000, altered both the cell-binding capacity and transactivating activity of Tat101, suggesting that this sulfated polysaccharide can make the protein less toxic. Sera raised against Tat101 and Tat101/Hep6000 similarly bound mainly to the N-terminal region of the protein, indicating that formation of the complex does not alter the B-cell immunodominant region. Anti-Tat101/Hep6000 antisera neutralized the transactivating activity of Tat101 more efficiently than anti-Tat101 antisera. Altogether, these results indicate that stabilization of Tat101 using sulfated sugars increases its immunogenicity and might be of value in increasing its vaccine efficacy.
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Affiliation(s)
- Alain Lecoq
- Commissariat de l'Energie Atomique, DSV, iBiTec-S, SIMOPRO, LCV, Gif-Sur-Yvette, France
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Setiyaningsih S, Desport M, Stewart ME, Hartaningsih N, Wilcox GE. Sequence analysis of mRNA transcripts encoding Jembrana disease virus Tat-1 in vivo. Virus Res 2008; 132:220-5. [DOI: 10.1016/j.virusres.2007.11.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2007] [Revised: 11/07/2007] [Accepted: 11/08/2007] [Indexed: 10/22/2022]
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Mahlknecht U, Dichamp I, Varin A, Van Lint C, Herbein G. NF-kappaB-dependent control of HIV-1 transcription by the second coding exon of Tat in T cells. J Leukoc Biol 2007; 83:718-27. [PMID: 18070983 DOI: 10.1189/jlb.0607405] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
HIV-1 two-exon transactivator protein (Tat) is a 101-aa protein. We investigated the possible contribution of the extreme C terminus of HIV-1 Tat to maximize nuclear transcription factor NF-kappaB activation, long terminal repeat (LTR) transactivation, and viral replication in T cells. C-terminal deletion and substitution mutants made with the infectious clone HIV-89.6 were assayed for their ability to transactivate NF-kappaB-secreted alkaline phosphatase and HIV-1 LTR-luciferase reporter constructs for low concentrations of Tat. A mutant infectious clone of HIV-89.6 engineered by introducing a stop codon at aa 72 in the Tat open-reading frame (HIVDeltatatexon2) replicated at a significantly lower rate than the wild-type HIV-89.6 in phytohemagglutinin-A/IL-2-stimulated primary peripheral blood lymphocytes. Altogether, our results suggest a critical role for the glutamic acids at positions 92, 94, and 96 or lysines at positions 88, 89, and 90, present in the second encoding Tat exon in activating NF-kappaB, transactivating the HIV-1 LTR and enhancing HIV-1 replication in T cells.
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Affiliation(s)
- Ulrich Mahlknecht
- Franche-Comté School of Medicine, Hôpital Saint-Jacques, 2 Place Saint-Jacques, F-25030 Besançon Cedex, France
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35
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Gorry PR, McPhee DA, Verity E, Dyer WB, Wesselingh SL, Learmont J, Sullivan JS, Roche M, Zaunders JJ, Gabuzda D, Crowe SM, Mills J, Lewin SR, Brew BJ, Cunningham AL, Churchill MJ. Pathogenicity and immunogenicity of attenuated, nef-deleted HIV-1 strains in vivo. Retrovirology 2007; 4:66. [PMID: 17888184 PMCID: PMC2075523 DOI: 10.1186/1742-4690-4-66] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2007] [Accepted: 09/23/2007] [Indexed: 11/10/2022] Open
Abstract
In efforts to develop an effective vaccine, sterilizing immunity to primate lentiviruses has only been achieved by the use of live attenuated viruses carrying major deletions in nef and other accessory genes. Although live attenuated HIV vaccines are unlikely to be developed due to a myriad of safety concerns, opportunities exist to better understand the correlates of immune protection against HIV infection by studying rare cohorts of long-term survivors infected with attenuated, nef-deleted HIV strains such as the Sydney blood bank cohort (SBBC). Here, we review studies of viral evolution, pathogenicity, and immune responses to HIV infection in SBBC members. The studies show that potent, broadly neutralizing anti-HIV antibodies and robust CD8+ T-cell responses to HIV infection were not necessary for long-term control of HIV infection in a subset of SBBC members, and were not sufficient to prevent HIV sequence evolution, augmentation of pathogenicity and eventual progression of HIV infection in another subset. However, a persistent T-helper proliferative response to HIV p24 antigen was associated with long-term control of infection. Together, these results underscore the importance of the host in the eventual outcome of infection. Thus, whilst generating an effective antibody and CD8+ T-cell response are an essential component of vaccines aimed at preventing primary HIV infection, T-helper responses may be important in the generation of an effective therapeutic vaccine aimed at blunting chronic HIV infection.
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Affiliation(s)
- Paul R Gorry
- Macfarlane Burnet Institute for Medical Research and Public Health, Melbourne, Victoria, Australia
- Department of Microbiology and Immunology, University of Melbourne, Melbourne, Victoria, Australia
- Department of Medicine, Monash University, Melbourne, Victoria, Australia
| | - Dale A McPhee
- Department of Microbiology and Immunology, University of Melbourne, Melbourne, Victoria, Australia
- Department of Microbiology, Monash University, Melbourne, Victoria, Australia
- National Serology Reference Laboratory, St. Vincent's Institute for Medical Research, Fitzroy, Victoria, Australia
| | - Erin Verity
- Macfarlane Burnet Institute for Medical Research and Public Health, Melbourne, Victoria, Australia
- Department of Microbiology, Monash University, Melbourne, Victoria, Australia
- National Serology Reference Laboratory, St. Vincent's Institute for Medical Research, Fitzroy, Victoria, Australia
| | - Wayne B Dyer
- Australian Red Cross Blood Service, Sydney, New South Wales, Australia
- Faculty of Medicine, University of Sydney, Sydney, New South Wales, Australia
| | - Steven L Wesselingh
- Macfarlane Burnet Institute for Medical Research and Public Health, Melbourne, Victoria, Australia
- Department of Microbiology and Immunology, University of Melbourne, Melbourne, Victoria, Australia
- Department of Medicine, Monash University, Melbourne, Victoria, Australia
| | - Jennifer Learmont
- Australian Red Cross Blood Service, Sydney, New South Wales, Australia
| | - John S Sullivan
- Australian Red Cross Blood Service, Sydney, New South Wales, Australia
- Faculty of Medicine, University of Sydney, Sydney, New South Wales, Australia
| | - Michael Roche
- Macfarlane Burnet Institute for Medical Research and Public Health, Melbourne, Victoria, Australia
| | - John J Zaunders
- Center for Immunology, St. Vincent's Hospital, Sydney, New South Wales, Australia
| | - Dana Gabuzda
- Dana-Farber Cancer Institute, Boston, MA, USA
- Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Suzanne M Crowe
- Macfarlane Burnet Institute for Medical Research and Public Health, Melbourne, Victoria, Australia
- Department of Medicine, Monash University, Melbourne, Victoria, Australia
| | - John Mills
- Department of Medicine, Monash University, Melbourne, Victoria, Australia
- Department of Microbiology, Monash University, Melbourne, Victoria, Australia
- Department of Epidemiology & Community Medicine, Monash University, Melbourne, Victoria, Australia
| | - Sharon R Lewin
- Department of Medicine, Monash University, Melbourne, Victoria, Australia
- Infectious Diseases Unit, Alfred Hospital, Melbourne, Victoria, Australia
| | - Bruce J Brew
- Department of Neurology, St. Vincent's Hospital, Sydney, New South Wales, Australia
| | | | - Melissa J Churchill
- Macfarlane Burnet Institute for Medical Research and Public Health, Melbourne, Victoria, Australia
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36
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Mayol K, Munier S, Beck A, Verrier B, Guillon C. Design and characterization of an HIV-1 Tat mutant: Inactivation of viral and cellular functions but not antigenicity. Vaccine 2007; 25:6047-60. [PMID: 17604883 DOI: 10.1016/j.vaccine.2007.05.048] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2006] [Revised: 04/02/2007] [Accepted: 05/13/2007] [Indexed: 11/19/2022]
Abstract
Among HIV-1 proteins, Tat is a promising antigen for consideration as a component of anti-HIV-1 vaccine formulations. Nevertheless, this viral protein is able to affect the expression of several cellular genes that are implicated in immune response. In this study, we designed and characterized a mutant form of Tat ("STLA Tat"), which is unable to transactivate viral transcription, and which has lost the deleterious effects on the expression of MHC I, IL-2, and CD25 genes compared with wild-type Tat, as observed in lymphoid Jurkat cells that stably express the tat genes. In vivo experiments in mice revealed that STLA Tat induces anti-Tat antibodies at the same titers as wild-type Tat, which recognize both autologous and heterologous Tat antigens. Finally, STLA Tat did not induce the immunosuppression observed after injection of wild-type Tat. Therefore, this STLA Tat mutant appears to be a safe and promising antigen for further evaluation in anti-HIV-1 vaccine strategies.
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Affiliation(s)
- Katia Mayol
- FRE2736 CNRS/bioMérieux, IFR128 BioSciences Lyon Gerland, 21 avenue Tony Garnier, 69365 Lyon cedex 07, France
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37
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Abstract
Tat (transactivator of transcription) is a small RNA-binding protein that plays a central role in the regulation of human immunodeficiency virus type 1 replication and in approaches to treating latently infected cells. Its interactions with a wide variety of both intracellular and extracellular molecules is well documented. A molecular understanding of the multitude of Tat activities requires a determination of its structure and interactions with cellular and viral partners. To increase the dispersion of NMR signals and permit dynamics analysis by multinuclear NMR spectroscopy, we have prepared uniformly 15N- and 15N/13C-labeled Tat-(1-72) protein. The cysteine-rich protein is unambiguously reduced at pH 4.1, and NMR chemical shifts and coupling constants suggest that it exists in a random coil conformation. Line broadening and multiple peaks in the Cys-rich and core regions suggest that transient folding occurs in two of the five sequence domains. NMR relaxation parameters were measured and analyzed by spectral density and Lipari-Szabo approaches, both confirming the lack of structure throughout the length of the molecule. The absence of a fixed conformation and the observation of fast dynamics are consistent with the ability of Tat protein to interact with a wide variety of proteins and nucleic acid and support the concept of a natively unfolded protein.
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Affiliation(s)
- Shaheen Shojania
- Department of Chemistry, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada
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38
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Klase Z, Donio MJ, Blauvelt A, Marx PA, Jeang KT, Smith SM. A peptide-loaded dendritic cell based cytotoxic T-lymphocyte (CTL) vaccination strategy using peptides that span SIV Tat, Rev, and Env overlapping reading frames. Retrovirology 2006; 3:1. [PMID: 16398928 PMCID: PMC1360091 DOI: 10.1186/1742-4690-3-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2005] [Accepted: 01/06/2006] [Indexed: 11/17/2022] Open
Abstract
CTL based vaccine strategies in the macaque model of AIDS have shown promise in slowing the progression to disease. However, rapid CTL escape viruses can emerge rendering such vaccination useless. We hypothesized that such escape is made more difficult if the immunizing CTL epitope falls within a region of the virus that has a high density of overlapping reading frames which encode several viral proteins. To test this hypothesis, we immunized macaques using a peptide-loaded dendritic cell approach employing epitopes in the second coding exon of SIV Tat which spans reading frames for both Env and Rev. We report here that autologous dendritic cells, loaded with SIV peptides from Tat, Rev, and Env, induced a distinct cellular immune response measurable ex vivo. However, conclusive in vivo control of a challenge inoculation of SIVmac239 was not observed suggesting that CTL epitopes within densely overlapping reading frames are also subject to escape mutations.
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MESH Headings
- Animals
- CD4 Lymphocyte Count
- DNA Primers
- Dendritic Cells/immunology
- Enzyme-Linked Immunosorbent Assay
- Gene Products, env/chemistry
- Gene Products, env/genetics
- Gene Products, env/immunology
- Gene Products, rev/chemistry
- Gene Products, rev/genetics
- Gene Products, rev/immunology
- Gene Products, tat/chemistry
- Gene Products, tat/genetics
- Gene Products, tat/immunology
- Macaca mulatta
- Molecular Sequence Data
- Mutation
- Peptide Fragments/immunology
- Polymerase Chain Reaction
- Reading Frames/genetics
- Simian Immunodeficiency Virus/immunology
- T-Lymphocytes, Cytotoxic/immunology
- Vaccination
- Vaccines, Subunit
- Viral Load
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Affiliation(s)
- Zachary Klase
- Department of Infectious Diseases, Saint Michael's Medical Center, Newark, New Jersey, USA
| | - Michael J Donio
- Department of Infectious Diseases, Saint Michael's Medical Center, Newark, New Jersey, USA
| | - Andrew Blauvelt
- Department of Dermatology, Oregon Health & Science University, Portland, Oregon, USA
- Department of Molecular Microbiology and Immunology, Oregon Health & Science University, Portland, Oregon, USA
- Dermatology Service, VA Medical Center, Portland, Oregon, USA
| | - Preston A Marx
- Tulane National Primate Research Center, Tulane University Health Sciences Center, Department of Tropical Medicine, Covington, Louisiana, USA
| | - Kuan-Teh Jeang
- Molecular Virology Section, Laboratory of Molecular Medicine, NIAID, NIH, Bethesda, Maryland, USA
| | - Stephen M Smith
- Department of Infectious Diseases, Saint Michael's Medical Center, Newark, New Jersey, USA
- Department of Preventive Medicine and Community Health, New Jersey Medical School, Newark, New Jersey, USA
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39
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Campbell GR, Watkins JD, Esquieu D, Pasquier E, Loret EP, Spector SA. The C terminus of HIV-1 Tat modulates the extent of CD178-mediated apoptosis of T cells. J Biol Chem 2005; 280:38376-82. [PMID: 16155003 DOI: 10.1074/jbc.m506630200] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
HIV infection and the progression to AIDS are characterized by the depletion of CD4(+) T cells through apoptosis of the uninfected bystander cells and the direct killing of HIV-infected cells. This is mediated in part by the human immunodeficiency virus, type 1 Tat protein, which is secreted by virally infected cells and taken up by uninfected cells and CD178 gene expression, which is critically involved in T cell apoptosis. The differing ability of HIV strains to induce death of infected and uninfected cells may play a role in the clinical and biological differences displayed by HIV strains. We chemically synthesized the 86-residue truncated short variant of Tat and its full-length form. We show that the trans-activation ability of Tat at the long terminal repeat does not correlate with T cell apoptosis but that the ability of Tat to up-regulate CD178 mRNA expression and induce apoptosis in T cells is critically dependent on the C terminus of Tat. Moreover, the greater 86-residue Tat-induced apoptosis is via the extrinsic pathway of CD95-CD178.
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Affiliation(s)
- Grant R Campbell
- Department of Pediatrics, Division of Infectious Diseases, University of California San Diego, La Jolla, California 92093-0672, USA
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40
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Ramakrishna L, Anand KK, Mohankumar KM, Ranga U. Codon optimization of the tat antigen of human immunodeficiency virus type 1 generates strong immune responses in mice following genetic immunization. J Virol 2004; 78:9174-89. [PMID: 15308713 PMCID: PMC506957 DOI: 10.1128/jvi.78.17.9174-9189.2004] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
DNA vaccines have been successful in eliciting potent immune responses in mice. Their efficiency, however, is restricted in larger animals. One reason for the limited performance of the DNA vaccines is the lack of molecular strategies to enhance immune responses. Additionally, genes directly cloned from pathogenic organisms may not be efficiently translated in a heterologous host expression system as a consequence of codon bias. To evaluate the influence of codon optimization on the immune response, we elected to use the Tat antigens of human immunodeficiency virus type 1 (HIV-1) (subtype C) and HIV-2, as these viral antigens are poorly immunogenic in natural infection and in experimental immunization and they are functionally important in viral infectivity and pathogenesis. Substituting codons that are optimally used in the mammalian system, we synthetically assembled Tat genes and compared them with the wild-type counterparts in two different mouse strains. Codon-optimized Tat genes induced qualitatively and quantitatively superior immune responses as measured in a T-cell proliferation assay, enzyme-linked immunospot assay, and chromium release assay. Importantly, while the wild-type genes promoted a mixed Th1-Th2-type cytokine profile, the codon-optimized genes induced a predominantly Th1 profile. Using a pepscan strategy, we mapped an immunodominant T-helper epitope to the core and basic domains of HIV-1 Tat. We also identified cross-clade immune responses between HIV-1 subtype B and C Tat proteins mapped to this T-helper epitope. Developing molecular strategies to optimize the immunogenicity of DNA vaccines is critical for inducing strong immune responses, especially to antigens like Tat. Our identification of a highly conserved T-helper epitope in the first exon of HIV-1 Tat of subtype C and the demonstration of a cross-clade immune response between subtypes B and C are important for a more rational design of an HIV vaccine.
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MESH Headings
- AIDS Vaccines/genetics
- AIDS Vaccines/immunology
- Amino Acid Sequence
- Animals
- Cell Division
- Codon/genetics
- Epitopes, T-Lymphocyte/chemistry
- Epitopes, T-Lymphocyte/immunology
- Gene Products, tat/biosynthesis
- Gene Products, tat/chemistry
- Gene Products, tat/genetics
- Gene Products, tat/immunology
- Genes, Viral/genetics
- Genetic Vectors/genetics
- HIV Antibodies/analysis
- HIV Antigens/biosynthesis
- HIV Antigens/chemistry
- HIV Antigens/genetics
- HIV Antigens/immunology
- HIV-1/classification
- HIV-1/genetics
- HIV-1/immunology
- Immunization
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Molecular Sequence Data
- Protein Biosynthesis
- T-Lymphocytes, Cytotoxic/immunology
- Th1 Cells/immunology
- Transcription, Genetic/genetics
- Vaccines, DNA/genetics
- Vaccines, DNA/immunology
- tat Gene Products, Human Immunodeficiency Virus
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Affiliation(s)
- Lakshmi Ramakrishna
- Molecular Virology Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore, India
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Campbell GR, Pasquier E, Watkins J, Bourgarel-Rey V, Peyrot V, Esquieu D, Barbier P, de Mareuil J, Braguer D, Kaleebu P, Yirrell DL, Loret EP. The glutamine-rich region of the HIV-1 Tat protein is involved in T-cell apoptosis. J Biol Chem 2004; 279:48197-204. [PMID: 15331610 DOI: 10.1074/jbc.m406195200] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Human immunodeficiency virus (HIV) infection and the progression to AIDS are characterized by the depletion of CD4(+) T-cells. HIV-1 infection leads to apoptosis of uninfected bystander cells and the direct killing of HIV-infected cells. This is mediated, in part, by the HIV-1 Tat protein, which is secreted by virally infected cells and taken up by uninfected cells. We chemically synthesized two 86-residue subtype D Tat proteins, Ug05RP and Ug11LTS, from two Ugandan patients who were clinically categorized as either rapid progressor or long-term survivor, with non-conservative mutations located essentially in the glutamine-rich region. Structural heterogeneities were revealed by CD, which translate into differing trans-activational and apoptotic effects. CD data analysis and molecular modeling indicated that the short alpha-helix observed in subtype D Tat proteins from rapid progressor patients such as Tat Mal and Tat Ug05RP is not present in Ug11LTS. We show that Tat Ug05RP is more efficient than Tat Ug11LTS in its trans-activational role and in inducing apoptosis in binding tubulin via the mitochondrial pathway. The glutamine-rich region of Tat appears to be involved in the Tat-mediated apoptosis of T-cells.
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Affiliation(s)
- Grant R Campbell
- CNRS Formation de Recherche en Evolution 2737, Faculté de Pharmacie, Université de la Méditerranée, 27, Boulevard Jean Moulin, 13385 Marseille, France
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42
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Abstract
Recent data have established the HIV-1 and SIV escape CTL through epitope mutation. However, three novel studies prove that such escape comes at a "cost" to overall viral fitness. Understanding how HIV-1/SIV escape CTL and the impact of the escape mutations has tremendous importance in developing CTL based vaccines. Further, a CTL based HIV-1 vaccine is likely to have long-term protective effect against disease only if the escape virus is significantly weakened compared with wild type.
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Affiliation(s)
- Stephen M Smith
- Saint Michael's Medical Center and The New Jersey Medical School, Newark, New Jersey 07102, USA.
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43
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Neuveut C, Scoggins RM, Camerini D, Markham RB, Jeang KT. Requirement for the second coding exon of Tat in the optimal replication of macrophage-tropic HIV-1. J Biomed Sci 2003. [DOI: 10.1007/bf02256316] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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