scholarly journals Human T-Cell Leukemia Virus Type 1 Tax Oncoprotein Suppression of Multilineage Hematopoiesis of CD34+ Cells In Vitro

2003 ◽  
Vol 77 (22) ◽  
pp. 12152-12164 ◽  
Author(s):  
Adam Tripp ◽  
Yingxian Liu ◽  
Michelle Sieburg ◽  
Joanne Montalbano ◽  
Stephen Wrzesinski ◽  
...  
Keyword(s):  
T Cell ◽  
Leukemia Virus ◽  
T Cell Leukemia ◽  
Cell Leukemia ◽  
Hematopoietic Progenitor ◽  
Cell Leukemia Virus Type ◽  
Human T Cell ◽  
T Cell Lines

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.

scholarly journals Tax and Overlapping Rex Sequences Do Not Confer the Distinct Transformation Tropisms of Human T-Cell Leukemia Virus Types 1 and 2

2003 ◽  
Vol 77 (14) ◽  
pp. 7728-7735 ◽  
Author(s):  
Jianxin Ye ◽  
Li Xie ◽  
Patrick L. Green
Keyword(s):  
T Cells ◽  
T Cell ◽  
Leukemia Virus ◽  
T Cell Leukemia ◽  
Cell Leukemia ◽  
Cell Leukemia Virus Type ◽  
Human T Cell ◽  
T Cell Leukemia Virus

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.

scholarly journals 5′-Long Terminal Repeat-Selective CpG Methylation of Latent Human T-Cell Leukemia Virus Type 1 Provirus In Vitro and In Vivo

2002 ◽  
Vol 76 (18) ◽  
pp. 9389-9397 ◽  
Author(s):  
Tsukasa Koiwa ◽  
Akiko Hamano-Usami ◽  
Takaomi Ishida ◽  
Akihiko Okayama ◽  
Kazunari Yamaguchi ◽  
...  
Keyword(s):  
Gene Expression ◽  
T Cell ◽  
Leukemia Virus ◽  
Cpg Methylation ◽  
T Cell Leukemia ◽  
Cell Leukemia ◽  
Cell Leukemia Virus Type ◽  
Human T Cell

ABSTRACT CpG methylation of the human T-cell leukemia virus type 1 (HTLV-1) long terminal repeat (LTR) has been implicated in proviral latency, but there is presently little information available regarding the pattern of LTR methylation and its effect on viral gene expression. To gain insight into the mechanisms of HTLV-1 latency, we have studied methylation of individual CpG sites in the U3-R region of the integrated proviral LTR by using bisulfite genomic sequencing methods. Surprisingly, our results reveal selective hypermethylation of the 5′ LTR and accompanying hypomethylation of the 3′ LTR in both latently infected cell lines and adult T-cell leukemia (ATL) cells having a complete provirus. Moreover, we observed a lack of CpG methylation in the LTRs of 5′-defective proviruses recovered from ATL samples, which is consistent with the selective hypomethylation of the 3′ LTR. Thus, the integrated HTLV-1 provirus in these carriers appears to be hypermethylated in the 5′ LTR and hypomethylated in the 3′ LTR. These results, together with the observation that proviral gene expression is reactivated by 5-azacytidine in latently infected cell lines, indicate that selective hypermethylation of the HTLV-1 5′ LTR is common both in vivo and in vitro. Thus, hypermethylation of the 5′ LTR appears to be an important mechanism by which HTLV-1 gene expression is repressed during viral latency.

scholarly journals Biochemical Characterization, Specificity and Inhibition Studies of HTLV-1, HTLV-2, and HTLV-3 Proteases

Life ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 127
Author(s):  
Norbert Kassay ◽  
János András Mótyán ◽  
Krisztina Matúz ◽  
Mária Golda ◽  
József Tőzsér
Keyword(s):  
T Cell ◽  
Biochemical Characterization ◽  
Leukemia Virus ◽  
T Cell Leukemia ◽  
Cell Leukemia ◽  
Cell Leukemia Virus Type ◽  
Adult T Cell Leukemia ◽  
Human T Cell ◽  
T Cell Leukemia Virus

The human T-lymphotropic viruses (HTLVs) are causative agents of severe diseases including adult T-cell leukemia. Similar to human immunodeficiency viruses (HIVs), the viral protease (PR) plays a crucial role in the viral life-cycle via the processing of the viral polyproteins. Thus, it is a potential target of anti-retroviral therapies. In this study, we performed in vitro comparative analysis of human T-cell leukemia virus type 1, 2, and 3 (HTLV-1, -2, and -3) proteases. Amino acid preferences of S4 to S1′ subsites were studied by using a series of synthetic oligopeptide substrates representing the natural and modified cleavage site sequences of the proteases. Biochemical characteristics of the different PRs were also determined, including catalytic efficiencies and dependence of activity on pH, temperature, and ionic strength. We investigated the effects of different HIV-1 PR inhibitors (atazanavir, darunavir, DMP-323, indinavir, ritonavir, and saquinavir) on enzyme activities, and inhibitory potentials of IB-268 and IB-269 inhibitors that were previously designed against HTLV-1 PR. Comparative biochemical analysis of HTLV-1, -2, and -3 PRs may help understand the characteristic similarities and differences between these enzymes in order to estimate the potential of the appearance of drug-resistance against specific HTLV-1 PR inhibitors.

scholarly journals Functional Comparison of HBZ and the Related APH-2 Protein Provides Insight into Human T-Cell Leukemia Virus Type 1 Pathogenesis

2016 ◽  
Vol 90 (7) ◽  
pp. 3760-3772 ◽  
Author(s):  
Amanda R. Panfil ◽  
Nathan J. Dissinger ◽  
Cory M. Howard ◽  
Brandon M. Murphy ◽  
Kristina Landes ◽  
...  
Keyword(s):  
T Cell ◽  
Leukemia Virus ◽  
Antisense Strand ◽  
T Cell Leukemia ◽  
Cell Leukemia ◽  
Cell Leukemia Virus Type ◽  
Human T Cell ◽  
T Cell Leukemia Virus

ABSTRACTHuman T-cell leukemia virus type 1 (HTLV-1) and type 2 (HTLV-2) are highly related retroviruses that transform T cellsin vitrobut have distinct pathological outcomesin vivo. HTLV-1 encodes a protein from the antisense strand of its proviral genome, the HTLV-1 basic leucine zipper factor (HBZ), which inhibits Tax-1-mediated viral transcription and promotes cell proliferation, a high proviral load, and persistencein vivo. In adult T-cell leukemia/lymphoma (ATL) cell lines and patient T cells,hbzis often the only viral gene expressed. The antisense strand of the HTLV-2 proviral genome also encodes a protein termed APH-2. Like HBZ, APH-2 is able to inhibit Tax-2-mediated viral transcription and is detectable in most primary lymphocytes from HTLV-2-infected patients. However, unlike HBZ, the loss of APH-2in vivoresults in increased viral replication and proviral loads, suggesting that HBZ and APH-2 modulate the virus and cellular pathways differently. Herein, we examined the effect of APH-2 on several known HBZ-modulated pathways: NF-κB (p65) transactivation, transforming growth factor β (TGF-β) signaling, and interferon regulatory factor 1 (IRF-1) transactivation. Like HBZ, APH-2 has the ability to inhibit p65 transactivation. Conversely, HBZ and APH-2 have divergent effects on TGF-β signaling and IRF-1 transactivation. Quantitative PCR and protein half-life experiments revealed a substantial disparity between HBZ and APH-2 transcript levels and protein stability, respectively. Taken together, our data further elucidate the functional differences between HBZ and APH-2 and how these differences can have profound effects on the survival of infected cells and, ultimately, pathogenesis.IMPORTANCEHuman T-cell leukemia virus type 1 (HTLV-1) and type 2 (HTLV-2) are highly related retroviruses that have distinct pathological outcomes in infected hosts. Functional comparisons of HTLV-1 and HTLV-2 proteins provide a better understanding about how HTLV-1 infection is associated with disease and HTLV-2 infection is not. The HTLV genome antisense-strand geneshbzandaph-2are often the only viral genes expressed in HTLV-infected T cells. Previously, our group found that HTLV-1 HBZ and HTLV-2 APH-2 had distinct effectsin vivoand hypothesized that the differences in the interactions of HBZ and APH-2 with important cell signaling pathways dictate whether cells undergo proliferation, apoptosis, or senescence. Ultimately, these functional differences may affect how HTLV-1 causes disease but HTLV-2 generally does not. In the current study, we compared the effects of HBZ and APH-2 on several HTLV-relevant cellular pathways, including the TGF-β signaling, NF-κB activation, and IRF-1 transactivation pathways.

scholarly journals Essential Role of Human T Cell Leukemia Virus Type 1orf-Iin Lethal Proliferation of CD4+Cells in Humanized Mice

2019 ◽  
Vol 93 (19) ◽  
Author(s):  
Veronica Galli ◽  
Christopher C. Nixon ◽  
Natasa Strbo ◽  
Maria Artesi ◽  
Maria F. de Castro-Amarante ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Leukemia Virus ◽  
Humanized Mice ◽  
T Cell Leukemia ◽  
Cell Leukemia ◽  
Cell Leukemia Virus Type ◽  
Human T Cell ◽  
T Cell Leukemia Virus

ABSTRACTHuman T cell leukemia virus type 1 (HTLV-1) is the ethological agent of adult T cell leukemia/lymphoma (ATLL) and a number of lymphocyte-mediated inflammatory conditions, including HTLV-1-associated myelopathy/tropical spastic paraparesis. HTLV-1orf-Iencodes two proteins, p8 and p12, whose functions in humans are to counteract innate and adaptive responses and to support viral transmission. However, thein vivorequirements fororf-Iexpression vary in different animal models. In macaques, the ablation oforf-Iexpression by mutation of its ATG initiation codon abolishes the infectivity of the molecular clone HTLV-1p12KO. In rabbits, HTLV-1p12KOis infective and persists efficiently. We used humanized mouse models to assess the infectivity of both wild-type HTLV-1 (HTLV-1WT) and HTLV-1p12KO. We found that NOD/SCID/γC−/−c-kit+mice engrafted with human tissues 1 day after birth (designated NSG-1d mice) were highly susceptible to infection by HTLV-1WT, with a syndrome characterized by the rapid polyclonal proliferation and infiltration of CD4+CD25+T cells into vital organs, weight loss, and death. HTLV-1 clonality studies revealed the presence of multiple clones of low abundance, confirming the polyclonal expansion of HTLV-1-infected cellsin vivo. HTLV-1p12KOinfection in a bone marrow-liver-thymus (BLT) mouse model prone to graft-versus-host disease occurred only following reversion of theorf-Iinitiation codon mutation within weeks after exposure and was associated with high levels of HTLV-1 DNA in blood and the expansion of CD4+CD25+T cells. Thus, the incomplete reconstitution of the human immune system in BLT mice may provide a window of opportunity for HTLV-1 replication and the selection of viral variants with greater fitness.IMPORTANCEHumanized mice constitute a useful model for studying the HTLV-1-associated polyclonal proliferation of CD4+T cells and viral integration sites in the human genome. The rapid death of infected animals, however, appears to preclude the clonal selection typically observed in human ATLL, which normally develops in 2 to 5% of individuals infected with HTLV-1. Nevertheless, the expansion of multiple clones of low abundance in these humanized mice mirrors the early phase of HTLV-1 infection in humans, providing a useful model to investigate approaches to inhibit virus-induced CD4+T cell proliferation.

scholarly journals Pentosan Polysulfate Demonstrates Anti-human T-Cell Leukemia Virus Type 1 ActivitiesIn VitroandIn Vivo

2019 ◽  
Vol 93 (16) ◽  
Author(s):  
Guangyong Ma ◽  
Jun-ichirou Yasunaga ◽  
Koichi Ohshima ◽  
Tadashi Matsumoto ◽  
Masao Matsuoka
Keyword(s):  
T Cell ◽  
Leukemia Virus ◽  
Spastic Paraparesis ◽  
T Cell Leukemia ◽  
Pentosan Polysulfate ◽  
Cell Leukemia ◽  
Cell Leukemia Virus Type ◽  
Human T Cell ◽  
Infected Cells

ABSTRACTHuman T-cell leukemia virus type 1 (HTLV-1) infection causes T-cell leukemia and inflammatory diseases, most notably including HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). The underlying mechanism for the pathogenesis of HAM/TSP remains unclear. According to a recent clinical trial, a humanized antibody that targets CCR4+cells ameliorates inflammation by reducing the number of infected cells in the central nervous system; this result suggests that the transmigration of HTLV-1-infected cells plays a crucial role in HAM/TSP. Partly due to the blood-brain barrier, current treatments for HAM/TSP are mostly palliative. Pentosan polysulfate (PPS), a semisynthetic glycosaminoglycan, has recently been used to treat HAM/TSP and was found to alleviate the symptoms. In this study, we investigated the effect of PPS on HTLV-1-infected cells and provide evidence for its efficacy in HAM/TSP. PPS was cytotoxic to certain HTLV-1-infected cells and significantly suppressed HTLV-1 virion production. PPS also efficiently inhibited HTLV-1 cell-cell transmission in T cells. In addition, PPS blocked HTLV-1 infection of primary endothelial cells (human umbilical vascular endothelial cells) and suppressed the subsequent induction of proinflammatory cytokine expression. Furthermore, PPS was found to inhibit the adhesion and transmigration of HTLV-1-infected cells. We also confirmed the anti-HTLV-1 effect of PPSin vivousing two mouse models. PPS blocked HTLV-1 infection in a mouse model with peripheral blood mononuclear cell (PBMC)-humanized NOD-scid IL2Rgammanull(huPBMC NSG) mice. PPS was also found to suppress the development of dermatitis and lung damage in HTLV-1 bZIP factor (HBZ)-transgenic (HBZ-Tg) mice, an HTLV-1 transgenic mouse model in which the mice develop systemic inflammation.IMPORTANCEHTLV-1 is the first human retrovirus to have been identified and is endemic in certain areas worldwide. HTLV-1 infection leads to the development of an inflammatory disease called HAM/TSP, a myelopathy characterized by slowly progressive spastic paraparesis. There have been no effective therapeutics available for HAM/TSP, but recently, a semisynthetic glycosaminoglycan, named pentosan polysulfate (PPS), has been found to alleviate the symptoms of HAM/TSP. Here we conducted a comprehensive study on the effect of PPS bothin vitroandin vivo. PPS demonstrated anti-HTLV-1 potential in infected cell lines, as shown by its suppressive effects on HTLV-1 replication and transmission and on the transmigration of infected T cells. Moreover, results obtained from two HTLV-1 mouse models demonstrate that PPS inhibits HTLV-1 infection and inflammation developmentin vivo. Our work offers insights into the treatment of HAM/TSP by PPS and also suggests its possible use for treating other HTLV-1-induced inflammatory diseases.

scholarly journals Hyperediting of human T-cell leukemia virus type 2 and simian T-cell leukemia virus type 3 by the dsRNA adenosine deaminase ADAR-1

2012 ◽  
Vol 93 (12) ◽  
pp. 2646-2651 ◽  
Author(s):  
Nga Ling Ko ◽  
Emmanuel Birlouez ◽  
Simon Wain-Hobson ◽  
Renaud Mahieux ◽  
Jean-Pierre Vartanian
Keyword(s):  
T Cell ◽  
Virus Type ◽  
Leukemia Virus ◽  
T Cell Leukemia ◽  
Cell Leukemia ◽  
Cell Leukemia Virus Type ◽  
Human T Cell ◽  
T Cell Leukemia Virus ◽  
Type 3

RNA editing mediated by adenosine deaminases acting on RNA (ADARs) converts adenosine (A) to inosine (I) residues in dsRNA templates. While ADAR-1-mediated editing was essentially described for RNA viruses, the present work addresses the issue for two δ-retroviruses, human T-cell leukemia virus type 2 and simian T-cell leukemia virus type 3 (HTLV-2 and STLV-3). We examined whether ADAR-1 could edit HTLV-2 and STLV-3 virus genomes in cell culture and in vivo. Using a highly sensitive PCR-based method, referred to as 3DI-PCR, we showed that ADAR-1 could hypermutate adenosine residues in HTLV-2. STLV-3 hypermutation was obtained without using 3DI-PCR, suggesting a higher mutation frequency for this virus. Detailed analysis of the dinucleotide editing context showed preferences for 5′ ArA and 5′ UrA. In conclusion, the present observations demonstrate that ADAR-1 massively edits HTLV-2 and STLV-3 retroviruses in vitro, but probably remains a rare phenomenon in vivo.

Human T-Cell Leukemia Virus Type I Tax Activates CD69 Gene Expression.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 2256-2256
Author(s):  
Chie Ishikawa ◽  
Taeko Okudaira ◽  
Tetsuro Nakazato ◽  
Mariko Tomita ◽  
Naoki Mori
Keyword(s):  
T Cell ◽  
Cell Lines ◽  
Leukemia Virus ◽  
Type I ◽  
T Cell Leukemia ◽  
Cell Leukemia ◽  
Cell Leukemia Virus Type ◽  
Human T Cell ◽  
Cd69 Expression ◽  
T Cell Lines

Abstract The human T-cell leukemia virus type I (HTLV-I) is an oncogenic retrovirus that is etiologically linked to the genesis of adult T-cell leukemia (ATL). Emerging evidence suggests that the pathogenicity of ATL involves suppression of the overall immune response, although the underlying mechanism remains unclear. In this study, we demonstrated that HTLV-I transactivator Tax induces the aberrant expression of CD69, an early leukocyte activation molecule that plays an important role in downregulation of the immune response. In a panel of HTLV-I-infected T-cell lines, CD69 expression was highly elevated compared to HTLV-I-negative T-cell lines at both mRNA and protein levels. Furthermore, CD69 expression correlated with Tax expression. Peripheral blood mononuclear cells from ATL patients also showed an increased expression of CD69 compared with controls. In vitro infection of a T-cell line with HTLV-I was associated with CD69 expression in conjunction with the increasing Tax expression. Expression of CD69 was dependent upon Tax expression in the inducible Tax-expressing cell line JPX-9. Tax transactivated the CD69 gene promoter in a transient transfection assay. Using Tax mutants and dominant negative mutants of IκBs, IKKs, NIK, and CREB, we demonstrated that Tax-induced CD69 expression required the NF-κB and CREB signaling pathways. A series of deletion and mutation analyses of the CD69 gene promoter indicated that two NF-κB, two EGR, and a CRE sequences were critical for Tax transactivation. Electrophoretic mobility shift assay showed the formation of specific protein-DNA complexes in HTLV-I-infected T-cell lines. These results suggest that Tax directly transactivated CD69 gene expression, through multiple cis-acting elements and by the interplay of transcription factors of the NF-κB, EGR, and CREB families. Tax-induced CD69 expression may be involved in immune suppression in ATL.

Sign in / Sign up

Export Citation Format

Share Document