1
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Pimenta de Paiva L, Coelho-dos-Reis JGA, Trindade BC, Peruhype-Magalhães V, Silva Araújo MS, Gonçalves JJ, Nogueira-Souza AC, Pereira Martins J, Lopes Ribeiro Á, Starling AL, Alcântara LCJ, Ribeiro MA, Carneiro-Proietti ABDF, Sabino EC, Alves Bicalho K, Teixeira-Carvalho A, Martins-Filho OA. A New Flow Cytometry-Based Single Platform for Universal and Differential Serodiagnosis of HTLV-1/2 Infection. Front Immunol 2022; 13:795815. [PMID: 35493505 PMCID: PMC9047958 DOI: 10.3389/fimmu.2022.795815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 03/18/2022] [Indexed: 11/28/2022] Open
Abstract
In the present work, we developed and evaluated the performance of a new flow cytometry-based single platform, referred to as “FC-Duplex IgG1 (HTLV-1/2)”, for universal and differential serodiagnosis of HTLV-1/2 infection. The proposed technology employs a system for detection of IgG1 antibodies in a single competitive immunofluorescence platform by flow cytometry using fluorescently labeled MT-2/MoT cell line mix coupled to a highly sensitive development system (Biotin/Streptavidin/Phycoerythrin). The stability of fluorescent labeling and the antigenicity of MT-2 and MoT cell lines were confirmed upon storage at −20°C for 2, 6, and 12 months. The anti-HTLV-1/2 IgG1 reactivity, expressed as percentage of positive fluorescent cells (PPFC), was evaluated for each target antigen along the titration curve of test serum samples (1:32 to 1:4,096). Upon selection of target cell line and serum dilutions with higher segregation score between groups, the performance of “FIX” and “FIX & PERM” protocols was evaluated. The “FIX” protocol presented excellent performance indices (Se = 92%/Sp = 94%/AUC = 0.96; Se = 96%/Sp = 100%/AUC = 0.99) for the universal (HTLV-1/2 vs. NI) and differential (HTLV-1 vs. HTLV-2) diagnosis of HTLV-1 infection, respectively. Optimization of the “FIX” protocol using the principle of synchronous and asynchronous pairwise analysis further improved the performance of “FC-Duplex IgG1 (HTLV-1/2)”, using the “FIX” protocol for differential diagnosis of HTLV-1 and HTLV-2 infections (Se = 100%/Sp = 100%/AUC = 1.00). In conclusion, the “FC-Duplex IgG1 (HTLV-1/2)” method represents an innovation in the biotechnology segment with the potential to compose a serological kit for differential diagnosis of HTLV-1/2 infection for reference laboratories and blood centers.
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Affiliation(s)
| | - Jordana Grazziela Alves Coelho-dos-Reis
- Instituto René Rachou, Fundação Oswaldo Cruz (FIOCRUZ)-Minas, Belo Horizonte, Brazil
- Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
- *Correspondence: Jordana Grazziela Alves Coelho-dos-Reis,
| | | | | | | | | | | | - Júlia Pereira Martins
- Instituto René Rachou, Fundação Oswaldo Cruz (FIOCRUZ)-Minas, Belo Horizonte, Brazil
| | - Ágata Lopes Ribeiro
- Instituto René Rachou, Fundação Oswaldo Cruz (FIOCRUZ)-Minas, Belo Horizonte, Brazil
- Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Ana Lucia Starling
- Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | | | - Maísa Aparecida Ribeiro
- Fundação Centro de Hematologia e Hemoterapia do Estado de Minas Gerais- Hemominas (HEMOMINAS), Belo Horizonte, Brazil
| | | | | | - Kelly Alves Bicalho
- Instituto René Rachou, Fundação Oswaldo Cruz (FIOCRUZ)-Minas, Belo Horizonte, Brazil
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2
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Martinez MP, Al-Saleem J, Green PL. Comparative virology of HTLV-1 and HTLV-2. Retrovirology 2019; 16:21. [PMID: 31391116 PMCID: PMC6686503 DOI: 10.1186/s12977-019-0483-0] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Accepted: 08/01/2019] [Indexed: 12/22/2022] Open
Abstract
Human T cell leukemia virus type 1 (HTLV-1) was the first discovered human retrovirus and the etiologic agent of adult T-cell leukemia and HTLV-1-associated myelopathy/tropical spastic paraparesis. Shortly after the discovery of HTLV-1, human T-cell leukemia virus type 2 (HTLV-2) was isolated from a patient with hairy cell leukemia. Despite possession of similar structural features to HTLV-1, HTLV-2 has not been definitively associated with lymphoproliferative disease. Since their discovery, studies have been performed with the goal of highlighting the differences between HTLV-1 and HTLV-2. A better understanding of these differences will shed light on the specific pathogenic mechanisms of HTLV-1 and lead to novel therapeutic targets. This review will compare and contrast the two oldest human retroviruses with regards to epidemiology, genomic structure, gene products, and pathobiology.
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Affiliation(s)
- Michael P Martinez
- Center for Retrovirus Research, The Ohio State University, Columbus, OH, USA.,Department of Veterinary Biosciences, The Ohio State University, Columbus, OH, USA
| | - Jacob Al-Saleem
- Center for Retrovirus Research, The Ohio State University, Columbus, OH, USA.,Department of Veterinary Biosciences, The Ohio State University, Columbus, OH, USA
| | - Patrick L Green
- Center for Retrovirus Research, The Ohio State University, Columbus, OH, USA. .,Department of Veterinary Biosciences, The Ohio State University, Columbus, OH, USA. .,Comprehensive Cancer Center, The Ohio State University, Columbus, OH, USA.
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3
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Assil S, Futsch N, Décembre E, Alais S, Gessain A, Cosset FL, Mahieux R, Dreux M, Dutartre H. Sensing of cell-associated HTLV by plasmacytoid dendritic cells is regulated by dense β-galactoside glycosylation. PLoS Pathog 2019; 15:e1007589. [PMID: 30818370 PMCID: PMC6413949 DOI: 10.1371/journal.ppat.1007589] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 03/12/2019] [Accepted: 01/22/2019] [Indexed: 01/20/2023] Open
Abstract
Human T Lymphotropic virus (HTLV) infection can persist in individuals resulting, at least in part, from viral escape of the innate immunity, including inhibition of type I interferon response in infected T-cells. Plasmacytoid dendritic cells (pDCs) are known to bypass viral escape by their robust type I interferon production. Here, we demonstrated that pDCs produce type I interferons upon physical cell contact with HTLV-infected cells, yet pDC activation inversely correlates with the ability of the HTLV-producing cells to transmit infection. We show that pDCs sense surface associated-HTLV present with glycan-rich structure referred to as biofilm-like structure, which thus represents a newly described viral structure triggering the antiviral response by pDCs. Consistently, heparan sulfate proteoglycans and especially the cell surface pattern of terminal β-galactoside glycosylation, modulate the transmission of the immunostimulatory RNA to pDCs. Altogether, our results uncover a function of virus-containing cell surface-associated glycosylated structures in the activation of innate immunity.
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Affiliation(s)
- Sonia Assil
- CIRI–Centre International de Recherche en Infectiologie, Univ Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, ENS Lyon, Lyon, France
| | - Nicolas Futsch
- CIRI–Centre International de Recherche en Infectiologie, Univ Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, ENS Lyon, Lyon, France
| | - Elodie Décembre
- CIRI–Centre International de Recherche en Infectiologie, Univ Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, ENS Lyon, Lyon, France
| | - Sandrine Alais
- CIRI–Centre International de Recherche en Infectiologie, Univ Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, ENS Lyon, Lyon, France
| | - Antoine Gessain
- Epidémiologie et Physiopathologie des Virus Oncogènes, Institut Pasteur, Paris France
| | - François-Loïc Cosset
- CIRI–Centre International de Recherche en Infectiologie, Univ Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, ENS Lyon, Lyon, France
| | - Renaud Mahieux
- CIRI–Centre International de Recherche en Infectiologie, Univ Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, ENS Lyon, Lyon, France
| | - Marlène Dreux
- CIRI–Centre International de Recherche en Infectiologie, Univ Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, ENS Lyon, Lyon, France
- * E-mail: (MD); (HD)
| | - Hélène Dutartre
- CIRI–Centre International de Recherche en Infectiologie, Univ Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, ENS Lyon, Lyon, France
- * E-mail: (MD); (HD)
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4
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Mizuguchi M, Sasaki Y, Hara T, Higuchi M, Tanaka Y, Funato N, Tanaka N, Fujii M, Nakamura M. Induction of Cell Death in Growing Human T-Cells and Cell Survival in Resting Cells in Response to the Human T-Cell Leukemia Virus Type 1 Tax. PLoS One 2016; 11:e0148217. [PMID: 26829041 PMCID: PMC4734616 DOI: 10.1371/journal.pone.0148217] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Accepted: 01/14/2016] [Indexed: 12/21/2022] Open
Abstract
Tax1 encoded by the human T-cell leukemia virus type 1 (HTLV-1) has been believed to dysregulate the expression of cellular genes involved in cell survival and mortality, leading to the development of adult T-cell leukemia (ATL). The function of Tax1 in ATL development however is still controversial, primarily because Tax1 induces cell cycle progression and apoptosis. To systemically understand cell growth phase-dependent induction of cell survival or cell death by Tax1, we established a single experimental system using an interleukin 2 (IL-2)-dependent human T-cell line Kit 225 that can be forced into resting phase by IL-2 deprivation. Introduction of Tax1 and HTLV-2 Tax (Tax2B) decreased mitochondrial activity alongside apoptosis in growing cells but not in resting cells. Cell cycle profile analysis indicated that Tax1 and Tax2B were likely to perturb the S phase in growing cells. Studies with Tax1 mutants and siRNA for NF-κB/RelA revealed that Tax1-mediated cell growth inhibition and apoptosis in growing Kit 225 cells depend on RelA. Interestingly, inactivation of the non-canonical NF-κB and p38 MAPK pathways relieved Tax1-mediated apoptosis, suggesting that the Tax1-NF-κB-p38 MAPK axis may be associated with apoptosis in growing cells. Inflammatory mediators such as CCL3 and CCL4, which are involved in oncogene-induced senescence (OIS), were induced by Tax1 and Tax2B in growing cells. In contrast, RelA silencing in resting cells reduced mitochondrial activity, indicating that NF-κB/RelA is also critical for Tax1-mediated cell survival. These findings suggest that Tax1-mediated cell survival and death depend on the cell growth phase. Both effects of Tax1 may be implicated in the long latency of HTLV-1 infection.
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Affiliation(s)
- Mariko Mizuguchi
- Human Gene Sciences Center, Tokyo Medical and Dental University, Tokyo, Japan
| | - Yuka Sasaki
- Human Gene Sciences Center, Tokyo Medical and Dental University, Tokyo, Japan
| | - Toshifumi Hara
- Division of Virology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Masaya Higuchi
- Division of Virology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Yuetsu Tanaka
- Department of Immunology, Graduate School and Faculty of Medicine, University of the Ryukyus, Okinawa, Japan
| | - Noriko Funato
- Human Gene Sciences Center, Tokyo Medical and Dental University, Tokyo, Japan
| | - Nobuyuki Tanaka
- Division of Cancer Biology and Therapeutics, Miyagi Cancer Center Research Institute, Miyagi, Japan
| | - Masahiro Fujii
- Division of Virology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Masataka Nakamura
- Human Gene Sciences Center, Tokyo Medical and Dental University, Tokyo, Japan
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5
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Preclinical efficacy of the synthetic retinoid ST1926 for treating adult T-cell leukemia/lymphoma. Blood 2014; 124:2072-80. [PMID: 25035162 DOI: 10.1182/blood-2014-03-560060] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Adult T-cell leukemia/lymphoma (ATL) is an aggressive neoplasm caused by human T-cell leukemia virus type 1 (HTLV-1). The HTLV-1 oncoprotein Tax plays an important role in ATL pathogenesis. ATL carries a poor prognosis due to chemotherapy resistance, stressing the need for alternative therapies. Here, we investigate the preclinical efficacy of the synthetic retinoid ST1926 in ATL and peripheral T-cell lymphomas. Clinically achievable concentrations of ST1926 induced a dramatic inhibition of cell proliferation in malignant T-cell lines and primary ATL cells with minimal effect on resting or activated normal lymphocytes. ST1926 induced apoptosis, DNA damage, and upregulation of p53 proteins in malignant T cells, whereas it caused an early downregulation of Tax proteins in HTLV-1-positive cells. In murine ATL, oral treatment with ST1926 prolonged survival and reduced leukemia cell infiltration, white blood cell counts, and spleen mass. In spleens of ST1926-treated animals, p53 and p21 proteins were upregulated, poly (ADP-ribose) polymerase was cleaved, and Tax transcripts were reduced. These results highlight the promising use of ST1926 as a targeted therapy for ATL.
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6
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Romanelli MG, Diani E, Bergamo E, Casoli C, Ciminale V, Bex F, Bertazzoni U. Highlights on distinctive structural and functional properties of HTLV Tax proteins. Front Microbiol 2013; 4:271. [PMID: 24058363 PMCID: PMC3766827 DOI: 10.3389/fmicb.2013.00271] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Accepted: 08/20/2013] [Indexed: 12/15/2022] Open
Abstract
Human T cell leukemia viruses (HTLVs) are complex human retroviruses of the Deltaretrovirus genus. Four types have been identified thus far, with HTLV-1 and HTLV-2 much more prevalent than HTLV-3 or HTLV-4. HTLV-1 and HTLV-2 possess strictly related genomic structures, but differ significantly in pathogenicity, as HTLV-1 is the causative agent of adult T cell leukemia and of HTLV-associated myelopathy/tropical spastic paraparesis, whereas HTLV-2 is not associated with neoplasia. HTLVs code for a protein named Tax that is responsible for enhancing viral expression and drives cell transformation. Much effort has been invested to dissect the impact of Tax on signal transduction pathways and to identify functional differences between the HTLV Tax proteins that may explain the distinct oncogenic potential of HTLV-1 and HTLV-2. This review summarizes our current knowledge of Tax-1 and Tax-2 with emphasis on their structure, role in activation of the NF-κB (nuclear factor kappa-B) pathway, and interactions with host factors.
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7
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Shirinian M, Kfoury Y, Dassouki Z, El-Hajj H, Bazarbachi A. Tax-1 and Tax-2 similarities and differences: focus on post-translational modifications and NF-κB activation. Front Microbiol 2013; 4:231. [PMID: 23966989 PMCID: PMC3744011 DOI: 10.3389/fmicb.2013.00231] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Accepted: 07/29/2013] [Indexed: 11/13/2022] Open
Abstract
Although human T cell leukemia virus type 1 and 2 (HTLV-1 and HTLV-2) share similar genetic organization, they have major differences in their pathogenesis and disease manifestation. HTLV-1 is capable of transforming T lymphocytes in infected patients resulting in adult T cell leukemia/lymphoma whereas HTLV-2 is not clearly associated with lymphoproliferative diseases. Numerous studies have provided accumulating evidence on the involvement of the viral transactivators Tax-1 versus Tax-2 in T cell transformation. Tax-1 is a potent transcriptional activator of both viral and cellular genes. Tax-1 post-translational modifications and specifically ubiquitylation and SUMOylation have been implicated in nuclear factor-kappaB (NF-κB) activation and may contribute to its transformation capacity. Although Tax-2 has similar protein structure compared to Tax-1, the two proteins display differences both in their protein–protein interaction and activation of signal transduction pathways. Recent studies on Tax-2 have suggested ubiquitylation and SUMOylation independent mechanisms of NF-κB activation. In this present review, structural and functional differences between Tax-1 and Tax-2 will be summarized. Specifically, we will address their subcellular localization, nuclear trafficking and their effect on cellular regulatory proteins. A special attention will be given to Tax-1/Tax-2 post-translational modification such as ubiquitylation, SUMOylation, phosphorylation, acetylation, NF-κB activation, and protein–protein interactions involved in oncogenecity both in vivo and in vitro.
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Affiliation(s)
- Margret Shirinian
- Department of Internal Medicine, Faculty of Medicine, American University of Beirut Beirut, Lebanon
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8
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Currer R, Van Duyne R, Jaworski E, Guendel I, Sampey G, Das R, Narayanan A, Kashanchi F. HTLV tax: a fascinating multifunctional co-regulator of viral and cellular pathways. Front Microbiol 2012; 3:406. [PMID: 23226145 PMCID: PMC3510432 DOI: 10.3389/fmicb.2012.00406] [Citation(s) in RCA: 103] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Accepted: 11/12/2012] [Indexed: 12/18/2022] Open
Abstract
Human T-cell lymphotropic virus type 1 (HTLV-1) has been identified as the causative agent of adult T-cell leukemia (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). The virus infects between 15 and 20 million people worldwide of which approximately 2-5% develop ATL. The past 35 years of research have yielded significant insight into the pathogenesis of HTLV-1, including the molecular characterization of Tax, the viral transactivator, and oncoprotein. In spite of these efforts, the mechanisms of oncogenesis of this pleiotropic protein remain to be fully elucidated. In this review, we illustrate the multiple oncogenic roles of Tax by summarizing a recent body of literature that refines our understanding of cellular transformation. A focused range of topics are discussed in this review including Tax-mediated regulation of the viral promoter and other cellular pathways, particularly the connection of the NF-κB pathway to both post-translational modifications (PTMs) of Tax and subcellular localization. Specifically, recent research on polyubiquitination of Tax as it relates to the activation of the IkappaB kinase (IKK) complex is highlighted. Regulation of the cell cycle and DNA damage responses due to Tax are also discussed, including Tax interaction with minichromosome maintenance proteins and the role of Tax in chromatin remodeling. The recent identification of HTLV-3 has amplified the importance of the characterization of emerging viral pathogens. The challenge of the molecular determination of pathogenicity and malignant disease of this virus lies in the comparison of the viral transactivators of HTLV-1, -2, and -3 in terms of transformation and immortalization. Consequently, differences between the three proteins are currently being studied to determine what factors are required for the differences in tumorogenesis.
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Affiliation(s)
- Robert Currer
- National Center for Biodefense and Infectious Diseases, George Mason University Manassas, VA, USA
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9
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Bidoia C. Human T-lymphotropic virus proteins and post-translational modification pathways. World J Virol 2012; 1:115-30. [PMID: 24175216 PMCID: PMC3782272 DOI: 10.5501/wjv.v1.i4.115] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Revised: 06/04/2012] [Accepted: 07/13/2012] [Indexed: 02/05/2023] Open
Abstract
Cell life from the cell cycle to the signaling transduction and response to stimuli is finely tuned by protein post-translational modifications (PTMs). PTMs alter the conformation, the stability, the localization, and hence the pattern of interactions of the targeted protein. Cell pathways involve the activation of enzymes, like kinases, ligases and transferases, that, once activated, act on many proteins simultaneously, altering the state of the cell and triggering the processes they are involved in. Viruses enter a balanced system and hijack the cell, exploiting the potential of PTMs either to activate viral encoded proteins or to alter cellular pathways, with the ultimate consequence to perpetuate through their replication. Human T-lymphotropic virus type 1 (HTLV-1) is known to be highly oncogenic and associates with adult T-cell leukemia/lymphoma, HTLV-1-associated myelopathy/tropical spastic paraparesis and other inflammatory pathological conditions. HTLV-1 protein activity is controlled by PTMs and, in turn, viral activity is associated with the modulation of cellular pathways based on PTMs. More knowledge is acquired about the PTMs involved in the activation of its proteins, like Tax, Rex, p12, p13, p30, HTLV-I basic leucine zipper factor and Gag. However, more has to be understood at the biochemical level in order to counteract the associated fatal outcomes. This review will focus on known PTMs that directly modify HTLV-1 components and on enzymes whose activity is modulated by viral proteins.
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Affiliation(s)
- Carlo Bidoia
- Carlo Bidoia, Centre for Research in Infectious Diseases, School of Medicine and Medical Science, University College Dublin, Belfield, Dublin 4, Ireland
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10
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The transcription profile of Tax-3 is more similar to Tax-1 than Tax-2: insights into HTLV-3 potential leukemogenic properties. PLoS One 2012; 7:e41003. [PMID: 22911729 PMCID: PMC3401231 DOI: 10.1371/journal.pone.0041003] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2012] [Accepted: 06/15/2012] [Indexed: 11/19/2022] Open
Abstract
Human T-cell Lymphotropic Viruses type 1 (HTLV-1) is the etiological agent of Adult T-cell Leukemia/Lymphoma. Although associated with lymphocytosis, HTLV-2 infection is not associated with any malignant hematological disease. Similarly, no infection-related symptom has been detected in HTLV-3-infected individuals studied so far. Differences in individual Tax transcriptional activity might account for these distinct physiopathological outcomes. Tax-1 and Tax-3 possess a PDZ binding motif in their sequence. Interestingly, this motif, which is critical for Tax-1 transforming activity, is absent from Tax-2. We used the DNA microarray technology to analyze and compare the global gene expression profiles of different T- and non T-cell types expressing Tax-1, Tax-2 or Tax-3 viral transactivators. In a T-cell line, this analysis allowed us to identify 48 genes whose expression is commonly affected by all Tax proteins and are hence characteristic of the HTLV infection, independently of the virus type. Importantly, we also identified a subset of genes (n = 70) which are specifically up-regulated by Tax-1 and Tax-3, while Tax-1 and Tax-2 shared only 1 gene and Tax-2 and Tax-3 shared 8 genes. These results demonstrate that Tax-3 and Tax-1 are closely related in terms of cellular gene deregulation. Analysis of the molecular interactions existing between those Tax-1/Tax-3 deregulated genes then allowed us to highlight biological networks of genes characteristic of HTLV-1 and HTLV-3 infection. The majority of those up-regulated genes are functionally linked in biological processes characteristic of HTLV-1-infected T-cells expressing Tax such as regulation of transcription and apoptosis, activation of the NF-κB cascade, T-cell mediated immunity and induction of cell proliferation and differentiation. In conclusion, our results demonstrate for the first time that, in T- and non T-cells types, Tax-3 is a functional analogue of Tax-1 in terms of transcriptional activation and suggest that HTLV-3 might share pathogenic features with HTLV-1 in vivo.
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Human T-cell leukemia virus type 2 antisense viral protein 2 is dispensable for in vitro immortalization but functions to repress early virus replication in vivo. J Virol 2012; 86:8412-21. [PMID: 22623800 DOI: 10.1128/jvi.00717-12] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Human T-cell leukemia virus type 1 (HTLV-1) and HTLV-2 are closely related but pathogenically distinct human retroviruses. The antisense strand of the HTLV-1 genome encodes HTLV-1 basic leucine zipper (b-ZIP) protein (HBZ), a protein that inhibits Tax-mediated viral transcription, enhances T-cell proliferation, and promotes viral persistence. Recently, an HTLV-2 antisense viral protein (APH-2) was identified. Despite its lack of a typical b-ZIP domain, APH-2, like HBZ, interacts with cyclic AMP response element binding protein (CREB) and downregulates Tax-mediated viral transcription. Here, we provide evidence that the APH-2 C-terminal LXXLL motif is important for CREB binding and Tax repression. In order to investigate the functional role of APH-2 in the HTLV-2-mediated immortalization of primary T lymphocytes in vitro and in HTLV-2 infection in vivo, we generated APH-2 mutant viruses. In cell cultures, the immortalization capacities of APH-2 mutant viruses were indistinguishable from that of wild-type HTLV-2 (wtHTLV-2), indicating that, like HBZ, APH-2 is dispensable for viral infection and cellular transformation. In vivo, rabbits inoculated with either wtHTLV-2 or APH-2 mutant viruses established a persistent infection. However, the APH-2 knockout virus displayed an increased replication rate, as measured by an increased viral antibody response and a higher proviral load. In contrast to HTLV-1 HBZ, we show that APH-2 is dispensable for the establishment of an efficient infection and persistence in a rabbit animal model. Therefore, antisense proteins of HTLV-1 and HTLV-2 have evolved different functions in vivo, and further comparative studies will provide fundamental insights into the distinct pathobiologies of these two viruses.
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Comparison of the Genetic Organization, Expression Strategies and Oncogenic Potential of HTLV-1 and HTLV-2. LEUKEMIA RESEARCH AND TREATMENT 2011; 2012:876153. [PMID: 23213551 PMCID: PMC3504254 DOI: 10.1155/2012/876153] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Accepted: 09/24/2011] [Indexed: 11/30/2022]
Abstract
Human T cell leukemia virus types 1 and 2 (HTLV-1 and HTLV-2) are genetically related complex retroviruses that are capable of immortalizing human T-cells in vitro and establish life-long persistent infections in vivo. In spite of these apparent similarities, HTLV-1 and HTLV-2 exhibit a significantly different pathogenic potential. HTLV-1 is recognized as the causative agent of adult T-cell leukemia/lymphoma (ATLL) and tropical spastic paraparesis/HTLV-1-associated myelopathy (TSP/HAM). In contrast, HTLV-2 has not been causally linked to human malignancy, although it may increase the risk of developing inflammatory neuropathies and infectious diseases. The present paper is focused on the studies aimed at defining the viral genetic determinants of the pathobiology of HTLV-1 and HTLV-2 through a comparison of the expression strategies and functional properties of the different gene products of the two viruses.
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13
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Bertazzoni U, Turci M, Avesani F, Di Gennaro G, Bidoia C, Romanelli MG. Intracellular localization and cellular factors interaction of HTLV-1 and HTLV-2 Tax proteins: similarities and functional differences. Viruses 2011; 3:541-560. [PMID: 21994745 PMCID: PMC3185761 DOI: 10.3390/v3050541] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2011] [Accepted: 04/26/2011] [Indexed: 12/24/2022] Open
Abstract
Human T-lymphotropic viruses type 1 (HTLV-1) and type 2 (HTLV-2) present very similar genomic structures but HTLV-1 is more pathogenic than HTLV-2. Is this difference due to their transactivating Tax proteins, Tax-1 and Tax-2, which are responsible for viral and cellular gene activation? Do Tax-1 and Tax-2 differ in their cellular localization and in their interaction pattern with cellular factors? In this review, we summarize Tax-1 and Tax-2 structural and phenotypic properties, their interaction with factors involved in signal transduction and their localization-related behavior within the cell. Special attention will be given to the distinctions between Tax-1 and Tax-2 that likely play an important role in their transactivation activity.
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Affiliation(s)
- Umberto Bertazzoni
- Department of Life and Reproduction Sciences, University of Verona, Strada le Grazie 8, 37134, Verona, Italy; E-Mails: (M.T.); (F.A.); (G.D.G.)
- Authors to whom correspondence should be addressed; E-Mails: (U.B.); (M.G.R); Tel.: +39-0458027182; Fax: +390458027180
| | - Marco Turci
- Department of Life and Reproduction Sciences, University of Verona, Strada le Grazie 8, 37134, Verona, Italy; E-Mails: (M.T.); (F.A.); (G.D.G.)
| | - Francesca Avesani
- Department of Life and Reproduction Sciences, University of Verona, Strada le Grazie 8, 37134, Verona, Italy; E-Mails: (M.T.); (F.A.); (G.D.G.)
| | - Gianfranco Di Gennaro
- Department of Life and Reproduction Sciences, University of Verona, Strada le Grazie 8, 37134, Verona, Italy; E-Mails: (M.T.); (F.A.); (G.D.G.)
| | - Carlo Bidoia
- Centre for Research in Infectious Diseases, University College Dublin, Belfield, Dublin 4, Ireland; E-Mail: (C.B.)
| | - Maria Grazia Romanelli
- Department of Life and Reproduction Sciences, University of Verona, Strada le Grazie 8, 37134, Verona, Italy; E-Mails: (M.T.); (F.A.); (G.D.G.)
- Authors to whom correspondence should be addressed; E-Mails: (U.B.); (M.G.R); Tel.: +39-0458027182; Fax: +390458027180
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Human T Lymphotropic Virus Type 1 (HTLV-1): Molecular Biology and Oncogenesis. Viruses 2010; 2:2037-2077. [PMID: 21994719 PMCID: PMC3185741 DOI: 10.3390/v2092037] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2010] [Revised: 08/25/2010] [Accepted: 09/15/2010] [Indexed: 12/13/2022] Open
Abstract
Human T lymphotropic viruses (HTLVs) are complex deltaretroviruses that do not contain a proto-oncogene in their genome, yet are capable of transforming primary T lymphocytes both in vitro and in vivo. There are four known strains of HTLV including HTLV type 1 (HTLV-1), HTLV-2, HTLV-3 and HTLV-4. HTLV-1 is primarily associated with adult T cell leukemia (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). HTLV-2 is rarely pathogenic and is sporadically associated with neurological disorders. There have been no diseases associated with HTLV-3 or HTLV-4 to date. Due to the difference in the disease manifestation between HTLV-1 and HTLV-2, a clear understanding of their individual pathobiologies and the role of various viral proteins in transformation should provide insights into better prognosis and prevention strategies. In this review, we aim to summarize the data accumulated so far in the transformation and pathogenesis of HTLV-1, focusing on the viral Tax and HBZ and citing appropriate comparisons to HTLV-2.
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Human T-cell leukemia virus type 2 produces a spliced antisense transcript encoding a protein that lacks a classic bZIP domain but still inhibits Tax2-mediated transcription. Blood 2009; 114:2427-38. [PMID: 19602711 DOI: 10.1182/blood-2008-09-179879] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Human T-cell leukemia virus type 1 (HTLV-1) and type 2 (HTLV-2) retroviruses infect T lymphocytes. The minus strand of the HTLV-1 genome encodes HBZ, a protein that could play a role in the development of leukemia in infected patients. Herein, we demonstrate that the complementary strand of the HTLV-2 genome also encodes a protein that we named APH-2 for "antisense protein of HTLV-2." APH-2 mRNA is spliced, polyadenylated, and initiates in the 3'-long terminal repeat at different positions. This transcript was detected in all HTLV-2-infected cell lines and short-term culture of lymphocytes obtained from HTLV-2 African patients tested and in 4 of 15 HTLV-2-infected blood donors. The APH-2 protein is 183 amino acids long, is localized in the cell nucleus, and is detected in vivo. Despite the lack of a consensus basic leucine zipper domain, APH-2 interacts with cyclic adenosine monophosphate-response element binding protein (CREB) and represses Tax2-mediated transcription in Tax2-expressing cells and in cells transfected with an HTLV-2 molecular clone. Altogether, our results demonstrate the existence of an antisense strand-encoded protein in HTLV-2, which could represent an important player in the development of disorders, such as lymphocytosis, which is frequently observed in HTLV-2 patients.
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Turci M, Lodewick J, Righi P, Polania A, Romanelli MG, Bex F, Bertazzoni U. HTLV-2B Tax oncoprotein is modified by ubiquitination and sumoylation and displays intracellular localization similar to its homologue HTLV-1 Tax. Virology 2009; 386:6-11. [PMID: 19195675 DOI: 10.1016/j.virol.2009.01.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2008] [Revised: 11/21/2008] [Accepted: 01/07/2009] [Indexed: 01/28/2023]
Abstract
HTLV-1 is more pathogenic than HTLV-2B. The difference is generally attributed to the properties of their individual transactivating Tax proteins. By using internal Flag-6His tagged Tax-1 and Tax-2B, which display transcriptional activities comparable to the untagged proteins and can be recognized by a single anti-Flag antibody, we demonstrate that Tax-2B is modified by ubiquitination and sumoylation. In addition, Tax2B is distributed in punctuate nuclear structures that include the RelA subunit of NF-kappaB, as has been previously demonstrated for Tax-1.
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Affiliation(s)
- Marco Turci
- Department of Mother and Child, Biology and Genetics, Section of Biology and Genetics, University of Verona, Strada Le Grazie 8, I-37134 Verona, Italy
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Human T-cell leukemia virus type 1 infection leads to arrest in the G1 phase of the cell cycle. J Virol 2008; 82:8442-55. [PMID: 18596104 DOI: 10.1128/jvi.00091-08] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Infection by the human T-cell leukemia virus type 1 (HTLV-1) is thought to cause dysregulated T-cell proliferation, which in turn leads to adult T-cell leukemia/lymphoma. Early cellular changes after HTLV-1 infection have been difficult to study due to the poorly infectious nature of HTLV-1 and the need for cell-to-cell contact for HTLV-1 transmission. Using a series of reporter systems, we show that HeLa cells cease proliferation within one or two division cycles after infection by HTLV-1 or transduction of the HTLV-1 tax gene. HTLV-1-infected HeLa cells, like their tax-transduced counterparts, expressed high levels of p21(CIP1/WAF1) and p27(KIP1), developed mitotic abnormalities, and became arrested in G(1) in senescence. In contrast, cells of a human osteosarcoma lineage (HOS) continued to divide after HTLV-1 infection or Tax expression, albeit at a reduced growth rate and with mitotic aberrations. Unique to HOS cells is the dramatic reduction of p21(CIP1/WAF1) and p27(KIP1) expression, which is in part associated with the constitutive activation of the phosphatidylinositol-3-kinase (PI3K)-protein kinase B (Akt) pathway. The loss of p21(CIP1/WAF1) and p27(KIP1) in HOS cells apparently allows HTLV-1- and Tax-induced G(1) arrest to be bypassed. Finally, HTLV-1 infection and Tax expression also cause human SupT1 T cells to arrest in the G(1) phase of the cell cycle. These results suggest that productive HTLV-1 infection ordinarily leads to Tax-mediated G(1) arrest. However, T cells containing somatic mutations that inactivate p21(CIP1/WAF1) and p27(KIP1) may continue to proliferate after HTLV-1 infection and Tax expression. These infected cells can expand clonally, accumulate additional chromosomal abnormalities, and progress to cancer.
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Montanheiro P, Olah I, Fukumori LMI, Smid J, Oliveira ACPD, Kanzaki LIB, Fonseca LAM, Duarte AJS, Casseb J. Low DNA HTLV-2 proviral load among women in São Paulo City. Virus Res 2008; 135:22-5. [PMID: 18343520 DOI: 10.1016/j.virusres.2008.01.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2007] [Revised: 01/28/2008] [Accepted: 01/30/2008] [Indexed: 12/01/2022]
Abstract
BACKGROUND HTLV-2 infections are almost always asymptomatic, and diseases associated with the infection are rarely reported. Little information is available on the relationship between HTLV-2 proviral load and gender or expression of disease, especially among patients with HIV-1 co-infection. METHODS We studied 77 HTLV-2-infected subjects followed in our clinic for the last 9 years; 53 (69%) of them were co-infected with HIV-1. HTLV-2 DNA proviral load (PVL) was measured by real time PCR, a test with a sensitivity of 10 in 10(4) PBMCs. RESULTS Six of 53HTLV-2/HIV-1 cases had a myelopathy (all of them had undetectable PVL of HTLV-2). Only 3 of 35 women (2 out of 3 co-infected with HIV) had a detectable PVL, whereas 10 of 42 men had a detectable PVL. Regardless of their HIV status women had significantly lower PVL than men (10 vs. 43 copies/10(4) PBMCs, p<0.05). CONCLUSIONS We noticed the occurrence of myelopathy in HTLV-2/HIV-1 co-infected patients, with undetectable HTLV-2 viral load. There was a sex difference in viral load for HTLV-2, what may be the result in mode of transmission or acquisition of the virus.
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Affiliation(s)
- Patrícia Montanheiro
- Laboratory of Dermatology and Immunology, São Paulo University Medical School, Sao Paulo, Brazil
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EAPB0203, a member of the imidazoquinoxaline family, inhibits growth and induces caspase-dependent apoptosis in T-cell lymphomas and HTLV-I-associated adult T-cell leukemia/lymphoma. Blood 2008; 111:3770-7. [PMID: 18218850 DOI: 10.1182/blood-2007-11-121913] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Imiquimod is an immune response modifier currently used as a topical treatment of genital warts, basal cell carcinoma, cutaneous metastasis of malignant melanoma, and vascular tumors. We developed more efficient killers from the same family of compounds that can induce apoptosis without the prominent pro-inflammatory response associated with imiquimod. Among these new products, tk;4EAPB0203, a member of the imidazo[1,2-a]quinoxalines, exhibits an important cytotoxic activity in vitro. HTLV-I-associated adult T-cell leukemia (ATL) and HTLV-I-negative peripheral T-cell lymphomas are associated with poor prognosis. Using potentially achievable concentrations of EAPB0203, we demonstrate inhibition of cell proliferation, G2/M cell- cycle arrest, and induction of apoptosis in HTLV-I-transformed and HTLV-I-negative malignant T cells and fresh ATL cells, whereas normal resting or activated T lymphocytes were resistant. EAPB0203 treatment significantly down-regulated the antiapoptotic proteins c-IAP-1 and Bcl-XL and resulted in a significant loss of mitochondrial membrane potential, cytoplasmic release of cytochrome c, and caspase-dependent apoptosis. Moreover, in HTLV-I-transformed cells only, EAPB0203 treatment stabilized p21 and p53 proteins but had no effect on NF-kappaB activation. These results support a potential therapeutic role for EAPB0203 in ATL and HTLV-I-negative T-cell lymphomas, either as a systemic or topical therapy for skin lesions.
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20
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Lacoste V, Nicot C, Gessain A, Valensi F, Gabarre J, Matta H, Chaudhary PM, Mahieux R. In primary effusion lymphoma cells, MYB transcriptional repression is associated with v-FLIP expression during latent KSHV infection while both v-FLIP and v-GPCR become involved during the lytic cycle. Br J Haematol 2007; 138:487-501. [PMID: 17659053 DOI: 10.1111/j.1365-2141.2007.06697.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Primary effusion lymphoma (PEL) is a rare, distinct subtype of non-Hodgkin lymphoma, which is associated with Kaposi sarcoma-associated herpesvirus (KSHV) infection. Although MYB levels are high in most neoplastic B cells, we found that, unexpectedly, both PEL cells and uncultured PEL patients' samples contained very low levels of MYB mRNA when compared to B-cell leukaemia samples obtained from KSHV(-) patients. These results were further confirmed at the protein level. Both latent viral FLICE inhibitory protein (v-FLIP) and early lytic viral G protein coupled receptor (v-GPCR) KSHV proteins were found to activate nuclear factor (NF)-kappaB and transrepress a MYB promoter reporter construct. In contrast, a dominant negative inhibitor of NF-kappaB (IkappaB-alpha) mutant prevented v-FLIP and v-GPCR from inhibiting MYB functions while a v-GPCR mutant that was impaired for NF-kappaB activation could not repress the MYB construct. Transduction of a v-FLIP expressing vector or stable transfection of v-GPCR both resulted in a marked downregulation of the endogenous MYB protein expression. However, MYB expression transactivated the lytic switch Replication and Transcription Activator (RTA) promoter in transient transfection assays. Taken together, our results demonstrate that, contrary to a number of other haematological malignancies, MYB expression is not required for PEL cell proliferation. Repressing MYB expression also helps in maintaining the virus in latency.
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MESH Headings
- CASP8 and FADD-Like Apoptosis Regulating Protein/metabolism
- Cell Line, Tumor
- Cell Transformation, Viral
- Gene Expression
- Gene Expression Regulation, Viral
- Genes, myb
- Herpesvirus 8, Human/physiology
- Humans
- Immediate-Early Proteins/metabolism
- Lymphoma, AIDS-Related/metabolism
- Lymphoma, AIDS-Related/virology
- Lymphoma, Non-Hodgkin/metabolism
- Lymphoma, Non-Hodgkin/virology
- NF-kappa B/metabolism
- Proto-Oncogene Proteins c-myb/analysis
- Receptors, G-Protein-Coupled/metabolism
- Sarcoma, Kaposi/metabolism
- Sarcoma, Kaposi/virology
- Trans-Activators/metabolism
- Transcription, Genetic
- Transduction, Genetic
- Transfection
- Viral Proteins/metabolism
- Virus Activation
- Virus Latency
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Affiliation(s)
- Vincent Lacoste
- Unité d'Epidémiologie et Physiopathologie des Virus Oncogènes, Institut Pasteur, Paris, France
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21
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Merling R, Chen C, Hong S, Zhang L, Liu M, Kuo YL, Giam CZ. HTLV-1 Tax mutants that do not induce G1 arrest are disabled in activating the anaphase promoting complex. Retrovirology 2007; 4:35. [PMID: 17535428 PMCID: PMC1894815 DOI: 10.1186/1742-4690-4-35] [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: 01/31/2007] [Accepted: 05/29/2007] [Indexed: 11/17/2022] Open
Abstract
HTLV-1 Tax is a potent activator of viral transcription and NF-κB. Recent data indicate that Tax activates the anaphase promoting complex/cyclosome (APC/C) ahead of schedule, causing premature degradation of cyclin A, cyclin B1, securin, and Skp2. Premature loss of these mitotic regulators is accompanied by mitotic aberrations and leads to rapid senescence and cell cycle arrest in HeLa and S. cerevisiae cells. Tax-induced rapid senescence (tax-IRS) of HeLa cells is mediated primarily by a dramatic stabilization of p27KIP and is also accompanied by a great surge in the level of p21CIP1mRNA and protein. Deficiencies in p27KIP prevent Tax-IRS. A collection of tax point mutants that permit normal growth of S. cerevisiae have been isolated. Like wild-type tax, many of them (C23W, A108T, L159F, and L235F) transactivate both the HTLV-LTR and the NF-κB reporters. One of them, V19M, preferentially activates NF-κB, but is attenuated for LTR activation. None of the mutants significantly elevated the levels of p21CIP1and p27KIP1, indicating that the dramatic surge in p21CIP1/WAF1and p27KIP 1induced by Tax is brought about by a mechanism distinct from NF-κB or LTR activation. Importantly, the ability of these mutants to activate APC/C is attenuated or abrogated. These data indicate that Tax-induced rapid senescence is causally associated with APC/C activation.
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Affiliation(s)
- Randall Merling
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Rd., Bethesda, MD 20814, USA
| | - Chunhua Chen
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Rd., Bethesda, MD 20814, USA
| | - Sohee Hong
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Rd., Bethesda, MD 20814, USA
| | - Ling Zhang
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Rd., Bethesda, MD 20814, USA
| | - Meihong Liu
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Rd., Bethesda, MD 20814, USA
| | - Yu-Liang Kuo
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Rd., Bethesda, MD 20814, USA
| | - Chou-Zen Giam
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Rd., Bethesda, MD 20814, USA
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Banerjee P, Rochford R, Antel J, Canute G, Wrzesinski S, Sieburg M, Feuer G. Proinflammatory cytokine gene induction by human T-cell leukemia virus type 1 (HTLV-1) and HTLV-2 Tax in primary human glial cells. J Virol 2007; 81:1690-700. [PMID: 17121800 PMCID: PMC1797548 DOI: 10.1128/jvi.01513-06] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2006] [Accepted: 11/14/2006] [Indexed: 01/04/2023] Open
Abstract
Infection with human T-cell leukemia virus type 1 (HTLV-1) can result in the development of HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), a chronic inflammatory disease of the central nervous system (CNS). HTLV-2 is highly related to HTLV-1 at the genetic level and shares a high degree of sequence homology, but infection with HTLV-2 is relatively nonpathogenic compared to HTLV-1. Although the pathogenesis of HAM/TSP remains to be fully elucidated, previous evidence suggests that elevated levels of the proinflammatory cytokines in the CNS are associated with neuropathogenesis. We demonstrate that HTLV-1 infection in astrogliomas results in a robust induction of interleukin-1beta (IL-1beta), IL-1alpha, tumor necrosis factor alpha (TNF-alpha), TNF-beta, and IL-6 expression. HTLV encodes for a viral transcriptional transactivator protein named Tax that also induces the transcription of cellular genes. To investigate and compare the effects of Tax1 and Tax2 expression on the dysregulation of proinflammatory cytokines, lentivirus vectors were used to transduce primary human astrocytomas and oligodendrogliomas. The expression of Tax1 in primary human astrocytomas and oligodendrogliomas resulted in significantly higher levels of proinflammatory cytokine gene expression compared to Tax2. Notably, Tax1 expression uniquely sensitized primary human astrocytomas to apoptosis. A Tax2/Tax1 chimera encoding the C-terminal 53 amino acids of the Tax1 fused to the Tax2 gene (Tax(221)) demonstrated a phenotype that resembled Tax1, with respect to proinflammatory cytokine gene expression and sensitization to apoptosis. The patterns of differential cytokine induction and sensitization to apoptosis displayed by Tax1 and Tax2 may reflect differences relating to the heightened neuropathogenicity associated with HTLV-1 infection and the development of HAM/TSP.
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Affiliation(s)
- Prabal Banerjee
- Department of Microbiology and Immunology, SUNY Upstate Medical University, 750 East Adams Street, Syracuse, NY 13210, USA
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Tosi G, Pilotti E, Mortara L, Barbaro ADL, Casoli C, Accolla RS. Inhibition of human T cell leukemia virus type 2 replication by the suppressive action of class II transactivator and nuclear factor Y. Proc Natl Acad Sci U S A 2006; 103:12861-6. [PMID: 16908858 PMCID: PMC1568938 DOI: 10.1073/pnas.0601589103] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2006] [Indexed: 11/18/2022] Open
Abstract
The master regulator of MHC-II gene transcription, class II transactivator (CIITA), acts as a potent inhibitor of human T cell leukemia virus type 2 (HTLV-2) replication by blocking the activity of the viral Tax-2 transactivator. Here, we show that this inhibitory effect takes place at the nuclear level and maps to the N-terminal 1-321 region of CIITA, where we identified a minimal domain, from positions 64-144, that is strictly required to suppress Tax-2 function. Furthermore, we show that Tax-2 specifically cooperates with cAMP response element binding protein-binding protein (CBP) and p300, but not with p300/CBP-associated factor, to enhance transcription from the viral promoter. This finding represents a unique difference with respect to Tax-1, which uses all three coactivators to transactivate the human T cell leukemia virus type 1 LTR. Direct sequestering of CBP or p300 is not the primary mechanism by which CIITA causes suppression of Tax-2. Interestingly, we found that the transcription factor nuclear factor Y, which interacts with CIITA to increase transcription of MHC-II genes, exerts a negative regulatory action on the Tax-2-mediated HTLV-2 LTR transactivation. Thus, CIITA may inhibit Tax-2 function, at least in part, through nuclear factor Y. These findings demonstrate the dual defensive role of CIITA against pathogens: it increases the antigen-presenting function for viral determinants and suppresses HTLV-2 replication in infected cells.
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Affiliation(s)
- Giovanna Tosi
- *Department of Clinical and Biological Sciences, University of Insubria, 21100 Varese, Italy; and
| | - Elisabetta Pilotti
- Department of Clinical Medicine, Nephrology, and Health Sciences, University of Parma, 43100 Parma, Italy
| | - Lorenzo Mortara
- *Department of Clinical and Biological Sciences, University of Insubria, 21100 Varese, Italy; and
| | - Andrea De Lerma Barbaro
- *Department of Clinical and Biological Sciences, University of Insubria, 21100 Varese, Italy; and
| | - Claudio Casoli
- Department of Clinical Medicine, Nephrology, and Health Sciences, University of Parma, 43100 Parma, Italy
| | - Roberto S. Accolla
- *Department of Clinical and Biological Sciences, University of Insubria, 21100 Varese, Italy; and
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Affiliation(s)
- Ethel Cesarman
- Department of Pathology and Laboratory Medicine, Division of Hematology-Oncology, Department of Medicine, Weill Medical College of Cornell University and The New York Presbyterian Hospital, New York, NY, USA
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25
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Sheehy N, Lillis L, Watters K, Lewis M, Gautier V, Hall W. Functional analysis of human T lymphotropic virus type 2 Tax proteins. Retrovirology 2006; 3:20. [PMID: 16551350 PMCID: PMC1462996 DOI: 10.1186/1742-4690-3-20] [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: 10/24/2005] [Accepted: 03/21/2006] [Indexed: 12/03/2022] Open
Abstract
Background The Tax proteins encoded by human T lymphotropic virus type 1 (HTLV-1) and type 2 (HTLV-2) are transcriptional activators of both the viral long terminal repeat (LTR) and cellular promoters via the CREB and NFkB pathways. In contrast to HTLV-1, HTLV-2 has been classified into four distinct genetic subtypes A, B, C and D defined by phylogenetic analysis of their nucleotide sequences and the size and amino acid sequence of their Tax proteins. In the present study we have analysed and compared the transactivating activities of three Tax 2A and one Tax 2B proteins using LTR and NFkB reporter assays. Results We found that with the exception of the prototype Tax 2A Mo protein, the other two Tax 2A proteins failed to transactivate either the viral LTR or NFkB promoter in Jurkat and 293T cells. Loss of activity was not associated with either expression levels or an alteration in subcellular distribution as all Tax 2 proteins were predominantly located in the cytoplasm of transfected cells. Analysis of the sequence of the two inactive Tax 2A proteins relative to Mo indicated that one had six amino acid changes and the other had one change in the central region of the protein. Mutations present at the amino and the extreme carboxy termini of Mo resulted in the loss of LTR but not NFkB activation whereas those occurring in the central region of the protein appeared to abolish transactivation of both promoters. Analysis of the transactivation phenotypes of Tax 1, Tax 2A Mo and Tax 2B containing mutations identified in the present study or previously characterised Tax mutations showed that domains required for LTR and NFkB activation are very similar but not identical in all three Tax proteins. Conclusion Our results suggest that loss of activity of two Tax 2A proteins derived from different isolates is associated with multiple amino acid changes relative to Mo in domains required for the activation of the CREB or CREB and NFkB pathways and that these domains are very similar but not identical in Tax 2B and Tax 1. The loss of Tax function in 2A viruses may have implications for their biological and pathogenic properties.
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Affiliation(s)
- Noreen Sheehy
- Centre for Research in Infectious Disease, School of Medicine & Medical Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Lorraine Lillis
- Centre for Research in Infectious Disease, School of Medicine & Medical Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Karen Watters
- Centre for Research in Infectious Disease, School of Medicine & Medical Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Martha Lewis
- University of California, Department of Medicine, UCLA Centre for Health Sciences, Los Angeles, California, USA
| | - Virginie Gautier
- Centre for Research in Infectious Disease, School of Medicine & Medical Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - William Hall
- Centre for Research in Infectious Disease, School of Medicine & Medical Science, University College Dublin, Belfield, Dublin 4, Ireland
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26
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Xie L, Yamamoto B, Haoudi A, Semmes OJ, Green PL. PDZ binding motif of HTLV-1 Tax promotes virus-mediated T-cell proliferation in vitro and persistence in vivo. Blood 2006; 107:1980-8. [PMID: 16263794 PMCID: PMC1895710 DOI: 10.1182/blood-2005-03-1333] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2005] [Accepted: 10/13/2005] [Indexed: 12/12/2022] Open
Abstract
HTLV-1 cellular transformation and disease induction is dependent on expression of the viral Tax oncoprotein. PDZ is a modular protein interaction domain used in organizing signaling complexes in eukaryotic cells through recognition of a specific binding motif in partner proteins. Tax-1, but not Tax-2, contains a PDZ-binding domain motif (PBM) that promotes the interaction with several cellular PDZ proteins. Herein, we investigate the contribution of the Tax-1 PBM in HTLV-induced proliferation and immortalization of primary T cells in vitro and viral survival in an infectious rabbit animal model. We generated several HTLV-1 and HTLV-2 Tax viral mutants, including HTLV-1deltaPBM, HTLV-2+C22(+PBM), and HTLV-2+ C18(deltaPBM). All Tax mutants maintained the ability to significantly activate the CREB/ATF or NFkappaB signaling pathways. Microtiter proliferation assays revealed that the Tax-1 PBM significantly increases both HTLV-1- and HTLV-2-induced primary T-cell proliferation. In addition, Tax-1 PBM was responsible for the micronuclei induction activity of Tax-1 relative to that of Tax-2. Viral infection and persistence were severely attenuated in rabbits inoculated with HTLV-1deltaPBM. Our results provide the first direct evidence suggesting that PBM-mediated associations between Tax-1 and cellular proteins play a key role in HTLV-induced cell proliferation and genetic instability in vitro and facilitate viral persistence in vivo.
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Affiliation(s)
- Li Xie
- Department of Veterinary Biosciences, The Ohio State University, 1925 Coffey Rd, Columbus, OH 43210, USA
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Turci M, Romanelli MG, Lorenzi P, Righi P, Bertazzoni U. Localization of human T-cell lymphotropic virus type II Tax protein is dependent upon a nuclear localization determinant in the N-terminal region. Gene 2005; 365:119-24. [PMID: 16337343 DOI: 10.1016/j.gene.2005.09.043] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2005] [Revised: 09/05/2005] [Accepted: 09/27/2005] [Indexed: 11/17/2022]
Abstract
Human T-cell lymphotropic viruses (HTLV) types I and II are closely related oncogenic retroviruses that have been associated with lymphoproliferative and neurological disorders. The proviral genome encodes a trans-regulatory Tax protein that activates viral genes and upregulates various cellular genes involved in both cell growth and transformation. Tax proteins of HTLV-I (Tax-I) and HTLV-II (Tax-II) exhibit more than 77% aa homology and expression of either Tax-I or Tax-II is sufficient for immortalization of cultured T lymphocytes. Tax-I shuttles from the nucleus to the cytoplasm and accumulates within the nucleus, whereas Tax-II is found mainly in the cytoplasm. In the present study we have used recombinant vectors to analyze the size and structure of the nuclear localization domain within the Tax-II protein sequence. The Tax-II protein was expressed in HeLa cells either as the complete protein, or regions thereof, that were individually fused to the green fluorescent protein (GFP). Immunoblot analysis of the fused Tax-II products confirmed their expression and size. Fluorescence microscopy studies indicated that the complete Tax-II as well as N-truncated forms presented a punctuate cytoplasmic distribution and that a nuclear localization determinant is confined to within the first 60 aa of Tax-II. Accordingly, site directed mutagenesis and deletion of specific sequences within the first 60 aa showed that the nuclear determinant lies within the first 41 residues of Tax-II. These results point to a direct involvement of the amino-terminal residues of Tax-II protein in determining its nuclear functionality.
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Affiliation(s)
- Marco Turci
- Department of Mother and Child, Biology and Genetics, University of Verona, Strada Le Grazie 8, 37134 Verona, Italy
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Chevalier SA, Meertens L, Calattini S, Gessain A, Kiemer L, Mahieux R. Presence of a functional but dispensable nuclear export signal in the HTLV-2 Tax protein. Retrovirology 2005; 2:70. [PMID: 16285885 PMCID: PMC1308865 DOI: 10.1186/1742-4690-2-70] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2005] [Accepted: 11/14/2005] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Human T-cell leukemia virus type 1 and type 2 are related human retroviruses. HTLV-1 is the etiological agent of the Adult T-cell Leukemia/Lymphoma and of the Tropical Spastic Paraparesis/HTLV-1 Associated Myelopathy, whereas, HTLV-2 infection has not been formally associated with any T-cell malignancy. HTLV-1 and 2 genomes encode, respectively, the Tax1 and Tax2 proteins whose role is to transactivate the viral promoter. HTLV-1 and HTLV-2 Tax sequences display 28% divergence at the amino acid level. Tax1 is a shuttling protein that possesses both a non canonical nuclear import (NLS) and a nuclear export (NES) signal. We have recently demonstrated that Tax1 and Tax2 display different subcellular localization and that residues 90-100 are critical for this process. We investigate in the present report, whether Tax2 also possesses a functional NES. RESULTS We first used a NES prediction method to determine whether the Tax2 protein might contain a NES and the results do suggest the presence of a NES sequence in Tax2. Using Green Fluorescent Protein-NES (GFP-NES) fusion proteins, we demonstrate that the Tax2 sequence encompasses a functional NES (NES2). As shown by microscope imaging, NES2 is able to mediate translocation of GFP from the nucleus, without the context of a full length Tax protein. Furthermore, point mutations or leptomycin B treatment abrogate NES2 function. However, within the context of full length Tax2, similar point mutations in the NES2 leucine rich stretch do not modify Tax2 localization. Finally, we also show that Tax1 NES function is dependent upon the positioning of the nuclear export signal "vis-à-vis" GFP. CONCLUSION HTLV-2 Tax NES is functional but dispensable for the protein localization in vitro.
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Affiliation(s)
- Sébastien A Chevalier
- Unité d'Epidémiologie et Physiopathologie des Virus Oncogènes, Institut Pasteur, Paris, France
| | - Laurent Meertens
- Unité d'Epidémiologie et Physiopathologie des Virus Oncogènes, Institut Pasteur, Paris, France
| | - Sara Calattini
- Unité d'Epidémiologie et Physiopathologie des Virus Oncogènes, Institut Pasteur, Paris, France
| | - Antoine Gessain
- Unité d'Epidémiologie et Physiopathologie des Virus Oncogènes, Institut Pasteur, Paris, France
| | - Lars Kiemer
- Center for Biological Sequence Analysis, BioCentrum-DTU, The Technical University of Denmark, Building 208 DK-2800, Lyngby, Denmark
| | - Renaud Mahieux
- Unité d'Epidémiologie et Physiopathologie des Virus Oncogènes, Institut Pasteur, Paris, France
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Tripp A, Banerjee P, Sieburg M, Planelles V, Li F, Feuer G. Induction of cell cycle arrest by human T-cell lymphotropic virus type 1 Tax in hematopoietic progenitor (CD34+) cells: modulation of p21cip1/waf1 and p27kip1 expression. J Virol 2005; 79:14069-78. [PMID: 16254341 PMCID: PMC1280183 DOI: 10.1128/jvi.79.22.14069-14078.2005] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2005] [Accepted: 08/23/2005] [Indexed: 11/20/2022] Open
Abstract
Human T-cell lymphotropic virus type 1 (HTLV-1) is the etiologic agent of adult T-cell leukemia, an aggressive CD4(+) malignancy. Although HTLV-2 is highly homologous to HTLV-1, infection with HTLV-2 has not been associated with lymphoproliferative disorders. Lentivirus-mediated transduction of CD34(+) cells with HTLV-1 Tax (Tax1) induced G(0)/G(1) cell cycle arrest and resulted in the concomitant suppression of multilineage hematopoiesis in vitro. Tax1 induced transcriptional upregulation of the cdk inhibitors p21(cip1/waf1) (p21) and p27(kip1) (p27), and marked suppression of hematopoiesis in immature (CD34(+)/CD38(-)) hematopoietic progenitor cells in comparison to CD34(+)/CD38(+) cells. HTLV-1 infection of CD34(+) cells also induced p21 and p27 expression. Tax1 also protected CD34(+) cells from serum withdrawal-mediated apoptosis. In contrast, HTLV-2 Tax (Tax2) did not detectably alter p21 or p27 gene expression, failed to induce cell cycle arrest, failed to suppress hematopoiesis in CD34(+) cells, and did not protect cells from programmed cell death. A Tax2/Tax1 chimera encoding the C-terminal 53 amino acids of Tax1 fused to Tax2 (Tax(221)) displayed a phenotype in CD34(+) cells similar to that of Tax1, suggesting that unique domains encoded within the C terminus of Tax1 may account for the phenotypes displayed in human hematopoietic progenitor cells. These remarkable differences in the activities of Tax1 and Tax2 in CD34(+) hematopoietic progenitor cells may underlie the sharp differences observed in the pathogenesis resulting from infection with HTLV-1 and HTLV-2.
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Affiliation(s)
- Adam Tripp
- Department of Microbiology & Immunology, SUNY Upstate Medical University, 750 East Adams St., Syracuse, NY 13210, USA
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Abstract
HTLV-1 and HTLV-2 are highly related complex retroviruses that have been studied intensely for nearly three decades because of their association with neoplasia, neuropathology, and/or their capacity to transform primary human T lymphocytes. The study of HTLV also represents an attractive model that has allowed investigators to dissect the mechanism of various cellular processes, several of which may be critical steps in HTLV-mediated pathogenesis. Both HTLV-1 and HTLV-2 can efficiently immortalize and transform T lymphocytes in cell culture and persist in infected individuals or experimental animals. However, the clinical manifestations of these two viruses differ significantly. HTLV-1 is associated with adult T-cell leukemia (ATL) and a variety of immune-mediated disorders including the chronic neurological disease termed HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). In contrast, HTLV-2 is much less pathogenic with reports of only a few cases of variant hairy cell leukemia and neurological disease associated with infection. The limited number of individuals shown to harbor HTLV-2 in association with specific diseases has, to date, precluded convincing epidemiological demonstration of a definitive etiologic role of HTLV-2 in human disease. Therefore, it has become clear that comparative studies designed to elucidate the mechanisms by which HTLV-1 and HTLV-2 determine distinct outcomes are likely to provide fundamental insights into the initiation of multistep leukemogenesis.
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Affiliation(s)
- Gerold Feuer
- Department of Microbiology and Immunology, SUNY Upstate Medical University, Syracuse, New York 13210, USA
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31
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Nasr R, El-Sabban ME, Karam JA, Dbaibo G, Kfoury Y, Arnulf B, Lepelletier Y, Bex F, de Thé H, Hermine O, Bazarbachi A. Efficacy and mechanism of action of the proteasome inhibitor PS-341 in T-cell lymphomas and HTLV-I associated adult T-cell leukemia/lymphoma. Oncogene 2004; 24:419-30. [PMID: 15543232 DOI: 10.1038/sj.onc.1208212] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
HTLV-I associated adult T-cell leukemia (ATL) and HTLV-I-negative peripheral T-cell lymphomas are associated with poor prognosis. Using pharmacological concentrations of the proteasome inhibitor PS-341, we demonstrate inhibition of cell proliferation and induction of apoptosis in fresh ATL cells, HTLV-I transformed and HTLV-I-negative malignant T cells, while normal resting or activated T lymphocytes were resistant. Combination of PS-341 and doxorubicin or etoposide resulted in an additive growth inhibition. In HTLV-I-negative malignant cells, PS-341 treatment significantly downregulated the antiapoptotic protein X-IAP and to a lesser extent c-IAP-1 and bcl-X(L) and resulted in caspase-dependent apoptosis. In HTLV-I transformed cells, the inhibition of the proteasomal degradation of Tax by PS-341 likely explains the relative protection of HTLV-I infected cells against caspase-dependent apoptosis. PS-341 treatment of these cells stabilized IkappaBalpha, IkappaBbeta, IkappaBvarepsilon, p21, p27 and p53 proteins and selectively inhibited Rel-A DNA binding NF-kappaB complexes. In both HTLV-I-positive and -negative cells, PS-341 treatment induced ceramide accumulation that correlated with apoptosis. We conclude that PS-341 affects multiple pathways critical for the survival of HTLV-I-positive and -negative malignant T cells supporting a potential therapeutic role for PS-341 in both ATL and HTLV-I-negative T-cell lymphomas, whether alone or in combination with chemotherapy.
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Affiliation(s)
- Rihab Nasr
- Department of Internal Medicine, Faculty of Medicine, American University of Beirut, Beirut, Lebanon
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32
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Sieburg M, Tripp A, Ma JW, Feuer G. Human T-cell leukemia virus type 1 (HTLV-1) and HTLV-2 tax oncoproteins modulate cell cycle progression and apoptosis. J Virol 2004; 78:10399-409. [PMID: 15367606 PMCID: PMC516438 DOI: 10.1128/jvi.78.19.10399-10409.2004] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2003] [Accepted: 05/25/2004] [Indexed: 11/20/2022] Open
Abstract
Human T-cell leukemia virus type 1 (HTLV-1) is the etiologic agent of adult T-cell leukemia and lymphoma, an aggressive clonal malignancy of human CD4-bearing T lymphocytes. HTLV-2, although highly related to HTLV-1 at the molecular level, has not been conclusively linked to development of lymphoproliferative disorders. Differences between the biological activities of the respective tax gene products (Tax1 and Tax2) may be one factor which accounts for the differential pathogenicities associated with infection. To develop an in vitro model to investigate and compare the effects of constitutive expression of Tax1 and Tax2, Jurkat T-cell lines were infected with lentivirus vectors encoding Tax1 and Tax2 in conjunction with green fluorescent protein, and stably transduced clonal cell lines were generated by serial dilution in the absence of drug selection. Jurkat cells that constitutively express Tax1 and Tax2 (Tax1/Jurkat and Tax2/Jurkat, respectively) showed notably reduced kinetics of cellular replication, and Tax1 inhibited cellular replication to a higher degree in comparison to Tax2. Tax1 markedly activated transcription from the cdk inhibitor p21(cip1/waf1) promoter in comparison to Tax2, suggesting that upregulation of p21(cip1/waf1) may account for the differential inhibition of cellular replication kinetics displayed by Tax1/Jurkat and Tax2/Jurkat cells. The presence of binucleated and multinucleated cells, reminiscent of large lymphocytes with cleaved or cerebriform nuclei often seen in HTLV-1- and -2-seropositive patients, was noted in cultures expressing Tax1 and Tax2. Although Tax1 and Tax2 expression mediated elevated resistance to apoptosis in Jurkat cells after serum deprivation, Tax1 was unique in protection from apoptosis after exposure to camptothecin and etoposide, inhibitors of topoisomerase I and II, respectively. Characterization of the unique phenotypes displayed by Tax1 and Tax2 in vitro will provide information as to the relative roles of these oncoproteins and their contribution to HTLV-1 and -2 pathogenesis in vivo.
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Affiliation(s)
- Michelle Sieburg
- SUNY Upstate Medical University, Department of Microbiology and Immunology, 750 East Adams St., Syracuse, NY 13210, USA
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33
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Meertens L, Chevalier S, Weil R, Gessain A, Mahieux R. A 10-amino acid domain within human T-cell leukemia virus type 1 and type 2 tax protein sequences is responsible for their divergent subcellular distribution. J Biol Chem 2004; 279:43307-20. [PMID: 15269214 DOI: 10.1074/jbc.m400497200] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human T-cell leukemia virus type 1 and type 2 (HTLV-1/2) are related retroviruses that infect T-lymphocytes. Whereas HTLV-1 infection can cause leukemia, HTLV-2 has not been demonstrated to be the agent of a hematological malignant disease. Nevertheless, the virally encoded Tax-1 and Tax-2 transactivators display a high percentage of similarity. Tax-1 is a shuttling protein that contains a noncanonical nuclear localization signal as well as a nuclear export signal. The presence of the nuclear localization signal and the nuclear export signal domains in the Tax-2 sequence has not been determined. The distribution of Tax-2 in infected cells is not known but has been assumed to be similar to that of Tax-1. By using a Tax-2-specific antibody, we report here that Tax-2 is located predominantly in the cytoplasm of the HTLV-2 immortalized or transformed infected T-cells. These results were confirmed after transient transfection of untagged Tax-1 and Tax-2 constructs, histidine tag Tax1/Tax2, GFP-Tax, and Tax-GFP fusion constructs in several cell lines. We show that this unanticipated localization is not due to a default in the Tax-2 nuclear localization signal functions nor to major differences in Tax-2 versus Tax-1 binding to the IKKgamma/NEMO protein. In addition, we demonstrate that inhibiting the proteasome results in a relocalization of Tax-1 in the cytoplasm, similar to that of Tax-2. By using a series of Tax-1/Tax-2 chimeras, we determined that the minimal domain that is necessary for Tax-2 peculiar distribution encompasses amino acids 90-100. Finally, we show a high correlation between intracellular localization of Tax and their NF-kappaB or CREB transactivating ability.
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Affiliation(s)
- Laurent Meertens
- Unité d'Epidémiologie et Physiopathologie des Virus Oncogènes, Institut Pasteur, 75724 Paris Cedex 15, France.
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34
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Meertens L, Pise-Masison C, Quere N, Brady J, Gessain A, Mahieux R. Utilization of the CBP but not the p300 co-activator by human T-lymphotropic virus type-2 Tax for p53 inhibition. Oncogene 2004; 23:5447-58. [PMID: 15156194 DOI: 10.1038/sj.onc.1207719] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We previously reported, both in transfected cells and in human T-cell leukemia virus type-2 subtype B infected cells, that the viral transactivator Tax-2B protein could inhibit p53 functions. We have now investigated the mechanism through which Tax-2B represses p53 using GFPTax-2B fusion proteins. We present evidence that Tax-2B inhibition of p53 function is not linked to CREB/ATF activation, but is uniquely correlated with the interaction of CREB binding protein (CBP), but not p300, with the C-terminus of Tax-2B. Wild type, but not a Tax-2B-M47 mutant, inhibits p53 function in adherent cells. We demonstrate that both Tax-2B and Tax-2B-M47 can bind p300, while Tax-2B-M47 is impaired for CBP binding. Importantly, transfection of increasing amounts of CBP but not p300 or p300/CBP-associated factor (P/CAF) could rescue p53 transcriptional activity in the presence of Tax-2B in nonlymphocytic cells. In lymphoid cells, Tax-2B mediated inhibition of p53 is correlated with the NF-kappaB pathway activation and could be prevented by the overexpression of an IkappaBalpha mutant. Given the similarities between the functional domains of CBP and p300, these results are intriguing and suggest that Tax-2B must bind the CR2 domain of CBP, but not that of p300 in order to repress p53.
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Affiliation(s)
- Laurent Meertens
- Unité d'Epidémiologie et Physiopathologie des Virus Oncogènes, Institut Pasteur, 28 rue du Docteur Roux, 75724 Paris cedex 15, France
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35
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Tripp A, Liu Y, Sieburg M, Montalbano J, Wrzesinski S, Feuer G. Human T-cell leukemia virus type 1 tax oncoprotein suppression of multilineage hematopoiesis of CD34+ cells in vitro. J Virol 2003; 77:12152-64. [PMID: 14581552 PMCID: PMC254283 DOI: 10.1128/jvi.77.22.12152-12164.2003] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2003] [Accepted: 08/13/2003] [Indexed: 11/20/2022] Open
Abstract
Human T-cell leukemia virus type 1 (HTLV-1) and HTLV-2 are highly related viruses that differ in disease manifestation. HTLV-1 is the etiologic agent of adult T-cell leukemia and lymphoma, an aggressive clonal malignancy of human CD4-bearing T lymphocytes. Infection with HTLV-2 has not been conclusively linked to lymphoproliferative disorders. We previously showed that human hematopoietic progenitor (CD34(+)) cells can be infected by HTLV-1 and that proviral sequences were maintained after differentiation of infected CD34(+) cells in vitro and in vivo. To investigate the role of the Tax oncoprotein of HTLV on hematopoiesis, bicistronic lentiviral vectors were constructed encoding the HTLV-1 or HTLV-2 tax genes (Tax1 and Tax2, respectively) and the green fluorescent protein marker gene. Human hematopoietic progenitor (CD34(+)) cells were infected with lentivirus vectors, and transduced cells were cultured in a semisolid medium permissive for the development of erythroid, myeloid, and primitive progenitor colonies. Tax1-transduced CD34(+) cells displayed a two- to fivefold reduction in the total number of hematopoietic clonogenic colonies that arose in vitro, in contrast to Tax2-transduced cells, which showed no perturbation of hematopoiesis. The ratio of colony types that developed from Tax1-transduced CD34(+) cells remained unaffected, suggesting that Tax1 inhibited the maturation of relatively early, uncommitted hematopoietic stem cells. Since previous reports have linked Tax1 expression with initiation of apoptosis, lentiviral vector-mediated transduction of Tax1 or Tax2 was investigated in CEM and Jurkat T-cell lines. Ectopic expression of either Tax1 or Tax2 failed to induce apoptosis in T-cell lines. These data demonstrate that Tax1 expression perturbs development and maturation of pluripotent hematopoietic progenitor cells, an activity that is not displayed by Tax2, and that the suppression of hematopoiesis is not attributable to induction of apoptosis. Since hematopoietic progenitor cells may serve as a latently infected reservoir for HTLV infection in vivo, the different abilities of HTLV-1 and -2 Tax to suppress hematopoiesis may play a role in the respective clinical outcomes after infection with HTLV-1 or -2.
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Affiliation(s)
- Adam Tripp
- Department of Microbiology and Immunology, SUNY Upstate Medical University, Syracuse, New York 13210, USA
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36
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Ye J, Xie L, Green PL. Tax and overlapping rex sequences do not confer the distinct transformation tropisms of human T-cell leukemia virus types 1 and 2. J Virol 2003; 77:7728-35. [PMID: 12829812 PMCID: PMC161933 DOI: 10.1128/jvi.77.14.7728-7735.2003] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2003] [Accepted: 04/15/2003] [Indexed: 11/20/2022] Open
Abstract
Human T-cell leukemia virus type 1 (HTLV-1) and HTLV-2 are distinct oncogenic retroviruses that infect several cell types but display their biological and pathogenic activity only in T cells. Previous studies have indicated that in vivo HTLV-1 has a preferential tropism for CD4+ T cells, whereas HTLV-2 in vivo tropism is less clear but appears to favor CD8+ T cells. Both CD4+ and CD8+ T cells are susceptible to HTLV-1 and HTLV-2 infection in vitro, and HTLV-1 has a preferential immortalization and transformation tropism of CD4+ T cells, whereas HTLV-2 immortalizes and transforms primarily CD8+ T cells. The molecular mechanism that determines this tropism of HTLV-1 and HTLV-2 has not been determined. HTLV-1 and HTLV-2 carry the tax and rex transregulatory genes in separate but partially overlapping reading frames. Since Tax has been shown to be critical for cellular transformation in vitro and interacts with numerous cellular processes, we hypothesized that the viral determinant of transformation tropism is encoded by tax. Using molecular clones of HTLV-1 (Ach) and HTLV-2 (pH6neo), we constructed recombinants in which tax and overlapping rex genes of the two viruses were exchanged. p19 Gag expression from proviral clones transfected into 293T cells indicated that both recombinants contained functional Tax and Rex but with significantly altered activity compared to the wild-type clones. Stable transfectants expressing recombinant viruses were established, irradiated, and cocultured with peripheral blood mononuclear cells. Both recombinants were competent to transform T lymphocytes with an efficiency similar to that of the parental viruses. Flow cytometry analysis indicated that HTLV-1 and HTLV-1/TR2 had a preferential tropism for CD4+ T cells and that HTLV-2 and HTLV-2/TR1 had a preferential tropism for CD8(+) T cells. Our results indicate that tax/rex in different genetic backgrounds display altered functional activity but ultimately do not contribute to the different in vitro transformation tropisms. This first study with recombinants between HTLV-1 and HTLV-2 is the initial step in elucidating the different pathobiologies of HTLV-1 and HTLV-2.
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Affiliation(s)
- Jianxin Ye
- Department of Veterinary Bioscience, The Ohio State University, 1925 Coffey Road, Columbus, OH 43210, USA
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Marriott SJ, Lemoine FJ, Jeang KT. Damaged DNA and miscounted chromosomes: human T cell leukemia virus type I tax oncoprotein and genetic lesions in transformed cells. J Biomed Sci 2002; 9:292-8. [PMID: 12145525 DOI: 10.1007/bf02256583] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Genetic instability is a recurring theme in human cancers. Although the molecular mechanisms mediating this effect commonly observed in transformed cells are not completely understood, it has been proposed to involve either the loss of DNA repair capabilities or the loss of chromosomal stability. The transforming retrovirus human T cell leukemia virus type I (HTLV-I) encodes a viral oncoprotein Tax, which is believed to cause the genomic instability characteristic of HTLV-I-infected cells. This review focuses on the ability of HTLV-I Tax to disrupt the cellular processes of DNA repair and chromosomal segregation. The consequences of these effects as well as the evolutionary advantage this may provide to HTLV-I are discussed.
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Affiliation(s)
- Susan J Marriott
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030, USA.
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38
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Meertens L, Mahieux R, Mauclère P, Lewis J, Gessain A. Complete sequence of a novel highly divergent simian T-cell lymphotropic virus from wild-caught red-capped mangabeys (Cercocebus torquatus) from Cameroon: a new primate T-lymphotropic virus type 3 subtype. J Virol 2002; 76:259-68. [PMID: 11739691 PMCID: PMC135714 DOI: 10.1128/jvi.76.1.259-268.2002] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Among 65 samples obtained from a primate rescue center located in Cameroon, two female adult red-capped mangabeys (Cercocebus torquatus) (CTO-602 and CTO-604), of wild-caught origin, had a peculiar human T-cell lymphotropic virus type 2 (HTLV-2)-like Western blot seroreactivity (p24, RGD21, +/-K55). Analyses of the simian T-cell lymphotropic virus type 3 (STLV-3)/CTO-604 complete proviral sequence (8,919 bp) indicated that this novel strain was highly divergent from HTLV-1 (60% nucleotide similarity), HTLV-2 (62%), or STLV-2 (62%) prototypes. It was, however, related to STLV-3/PH-969 (87%), a divergent STLV strain previously isolated from an Eritrean baboon. The STLV-3/CTO-604 sequence possesses the major open reading frames corresponding to the structural, enzymatic, and regulatory proteins. However, its long terminal repeat is shorter, with only two 21-bp repeats. Furthermore, as demonstrated by reverse transcriptase PCR, this new STLV exhibits significant differences from STLV-3/PH-969 at the mRNA splice junction position level. In all phylogenetic analyses, STLV-3/CTO-604 and STLV-3/PH-969 clustered in a highly supported single clade, indicating an evolutionary lineage independent from primate T-lymphotropic virus type 1 (PTLV-1) and PTLV-2. Nevertheless, the nucleotide divergence between STLV-3/PH-969 and STLV-3/CTO-604 is equivalent to or higher than the divergence observed between the different HTLV-1 or HTLV-2 subtypes. Thus, the STLV-3/CTO-604 strain can be considered the prototype of a second subtype in the PTLV-3 type. The presence of two related viruses in evolutionarily distantly related African monkeys species, living in two opposite ecosystems (rain forest versus desert), reinforces the possible African origin of PTLV and opens new avenues regarding the search for a possible human counterpart of these viruses in individuals exhibiting such HTLV-2-like seroreactivities.
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Affiliation(s)
- Laurent Meertens
- Unité d'Epidémiologie et Physiopathologie des Virus Oncogènes, Département du SIDA et des Rétrovirus, Institut Pasteur, 75724 Paris Cedex 15, France
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