記述言語：英語   掲載種別：研究論文（学術雑誌）  

N-myc downstream-regulated gene 2 (NDRG2) is a candidate tumor suppressor that is frequently downregulated in adult T-cell leukemia/lymphoma (ATLL) and functions to negatively regulate several cellular signaling pathways as PP2A recruiter. To clarify the molecular mechanisms of suppression of NDRG2 expression, we initially determined the expression pattern of NDRG2 in various types of T-cells and ATLL cells. NDRG2 expression was significantly upregulated in HTLV-1/Tax-immortalized T-cells, which was mediated by NF-κB activation through Tax expression. On the other hand, NDRG2 expression was suppressed in HTLV-1-infected cell lines and various types of ATLL cells, which was dependent on the DNA methylation of the NDRG2 promoter. We found that the expression of enhancer of zeste homolog 2 (EZH2), a member of the polycomb family, is increased in ATLL, and that EZH2 directly binds to the NDRG2 promoter and induces DNA methylation of the NDRG2 promoter. Since the expression of EZH2 were anti-parallelly regulated with the NDRG2 expression, EZH2 might be one of the most important regulators of the downregulation of NDRG2, contributing to enhanced activation of signaling pathways during ATLL development.

DOI： 10.1016/j.bbadis.2019.07.001

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1038/s41598-019-46237-1

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Tau aggregates in neurons of brain lesions is a hallmark pathology of tauopathies, including Alzheimer's disease (AD). Recent studies suggest that the RNA-binding protein TIA1 initiates Tau aggregation by inducing the formation of stress granules (SGs) containing Tau. SGs are stress-inducible cytoplasmic protein aggregates containing many RNA-binding proteins that has been implicated as an initial site of multiple pathogenic protein aggregates in several neurodegenerative diseases. In this study, we found that ubiquitin-specific protease 10 (USP10) is a critical factor for the formation of Tau/TIA1/USP10-positive SGs. Proteasome inhibition or TIA1-overexpression in HT22 neuronal cells induced the formation of TIA1/Tau-positive SGs, and the formations were severely attenuated by depletion of USP10. In addition, the overexpression of USP10 without stress stimuli in HT22 cells induced TIA1/Tau/USP10-positive SGs in a deubiquitinase-independent manner. In AD brain lesions, USP10 was colocalized with Tau aggregates in the cell body of neurons. The present findings suggest that USP10 plays a key role in the initiation of pathogenic Tau aggregation in AD through SG formation.

DOI： 10.1038/s41598-019-47033-7

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1038/s41598-019-39424-7

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.isci.2018.11.006

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DOI： 10.1186/s12977-018-0454-x

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Tokyo  

Membrane-associated guanylate kinase with inverted orientation protein 1 (MAGI-1) is a cytoplasmic scaffold protein that interacts with various signaling molecules
it negatively controls the cell growth of various types of cells and positively controls cell–cell interaction. In T cells, MAGI-1 has been shown to inhibit Akt activity through its interaction with PTEN and MEK1. In this study we found that MAGI-1 expression is decreased in multiple (9 out of 15) human T-cell leukemia cell lines, including adult T-cell leukemia (ATL), T-cell acute lymphoblastic leukemia and chronic T-cell lymphocytic leukemia. The overexpression of MAGI-1 protein in a MAGI-1-low ATL cell line reduced cellular growth. While the overexpression of MAGI-1 protein in a MAGI-1-low ATL cell line reduced the Akt and MEK activities, the knockdown of MAGI-1 in a MAGI-1-high ATL cell line augmented the Akt and MEK activities. Collectively, the findings of the present study suggest that the decreased expression of MAGI-1 in human T cells contributes to the development of several types of T-cell leukemia, partly through the stimulation of the Akt and MEK pathways.

DOI： 10.1007/s12185-017-2359-1

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記述言語：英語  

Sex-determining region Y-box 2 (SOX2) is an essential factor involved in the self-renewal and pluripotency of embryonic stem cells and has functions in cell survival and progression in many types of cancers. Here, we found that several endometrial cancer cell lines expressed SOX2, which was required for cell growth. Additionally, SOX2 overexpression regulated the expression of cyclin-dependent kinase inhibitor 1A (CDKN1A), and SOX2 specifically bound to p21 promoter DNA in endometrial cancer cell lines expressing SOX2. Expressions of SOX2 in endometrial cancer patients were significantly correlated with histological grade and poor prognosis. Moreover, low p21 together with high SOX2 expressions in advanced endometrial cancer patients were associated with the most unfavorable outcomes of patients. These results indicated that simultaneous measurement of SOX2 and p21 expression in endometrial cancer patients may be a useful biomarker for patient prognosis.

DOI： 10.1111/cas.13196

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：CELL PRESS  

Self-renewal, replication, and differentiation of hematopoietic stem cells (HSCs) are regulated by cytokines produced by niche cells in fetal liver and bone marrow. HSCs must overcome stresses induced by cytokine deprivation during normal development. In this study, we found that ubiquitin-specific peptidase 10 (USP10) is a crucial deubiquitinase for mouse hematopoiesis. All USP10 knockout (KO) mice died within 1 year because of bone marrow failure with pancytopenia. Bone marrow failure in these USP10-KO mice was associated with remarkable reductions of long-term HSCs (LT-HSCs) in bone marrow and fetal liver. Such USP10-KO fetal liver exhibited enhanced apoptosis of hematopoietic stem/progenitor cells (HSPCs) including LT-HSCs but not of lineage-committed progenitor cells. Transplantation of USP10-competent bone marrow cells into USP10-KO mice reconstituted multilineage hematopoiesis. These results suggest that USP10 is an essential deubiquitinase in hematopoiesis and functions by inhibiting apoptosis of HSPCs including LT-HSCs.

DOI： 10.1016/j.stemcr.2016.11.003

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PUBLIC LIBRARY SCIENCE  

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-kappa B/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-kappa B and p38 MAPK pathways relieved Tax1-mediated apoptosis, suggesting that the Tax1-NF-kappa B-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-kappa B/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.

DOI： 10.1371/journal.pone.0148217

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER  

Human T-cell leukemia virus type 1 (HTLV-1) is a causative retrovirus of adult T-cell leukemia and HTLV-1-associated myelopathy. Unlike HTLV-1, the same group of retrovirus HTLV-2 has not been found to be associated with these diseases. HTLV-1 and HTLV-2 encode transforming proteins Tax1 and Tax2, and a few distinct activities of Tax1 from those of Tax2 have been proposed to contribute to the HTLV-1-specific pathogenesis of disease. One significant difference of Tax1 from Tax2 is the activation of transcription factor NF-kappa B2/p100/p52. We found that Tax1 but not Tax2 induces the expression of OX40 ligand (OX40L) in a human T-cell line. To induce the OX40L expression, Tax1 but not Tax2 was observed to interact with NF-kappa B2/p100/p52 and RelB and the distinct interaction activity was mediated by the Tax1 amino acid region of 225-232. In addition, Tax1 but not Tax2 or Tax1/225-232 interacted with p65, p50, and c-Rel; however, the interactions were much less than those noted with NF-kappa B2/p100/p52 and RelB. OX40L is a T-cell costimulatory molecule of the tumor necrosis factor family, and its signal plays a critical role in establishing adaptive immunity by inducing the polarized differentiation of T-cells to cells such as T helper type 2 and T follicular helper cells. Therefore, the present findings suggest that Tax1 might alter the immune response to HTLV-1 and/or differentiation of HTLV-1-infected T-cells via OX40L induction, thereby acting as a factor mediating the distinct phenotypes and pathogenesis of HTLV-1 from that of HTLV-2.

DOI： 10.1007/s11262-015-1277-7

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：BIOMED CENTRAL LTD  

BACKGROUND: Adult T-cell leukemia (ATL) is a CD4(+) T-cell neoplasm with a poor prognosis. A previous study has shown that there is a strong correlation between the secreted matricellular protein osteopontin (OPN) level and disease severity in ATL patients. Here, we investigated the role of OPN in ATL pathogenesis and the possible application of anti-OPN monoclonal antibody (mAb) for ATL immunotherapy in NOD/Shi-scid,IL-2Rg (null) (NOG) mice. RESULTS: Subcutaneous inoculation of ATL cell lines into NOG mice increased the plasma level of OPN, which significantly correlated with metastasis of the inoculated cells and survival time. Administration of an SVVYGLR motif-recognizing anti-OPN mAb resulted in inhibition not only of tumor growth but also of tumor invasion and metastasis. The number of fibroblast activating protein-positive fibroblasts was also reduced by this mAb. We then co-inoculated mouse embryonic fibroblasts (MEFs) isolated from wild-type (WT) or OPN knockout mice together with ATL-derived TL-OmI cells into the NOG mice. The mice co-inoculated with WT MEFs displayed a significant decrease in survival relative to those injected with TL-OmI cells alone and the absence of OPN in MEFs markedly improved the survival rate of TL-OmI-inoculated mice. In addition, tumor volume and metastasis were also reduced in the absence of OPN. CONCLUSION: We showed that the xenograft NOG mice model can be a useful system for assessment of the physiological role of OPN in ATL pathogenesis. Using this xenograft model, we found that fibroblast-derived OPN was involved in tumor growth and metastasis, and that this tumor growth and metastasis was significantly suppressed by administration of the anti-OPN mAbs. Our findings will lead to a novel mAb-mediated immunotherapeutic strategy targeting against the interaction of OPN with integrins on the tumor of ATL patients.

DOI： 10.1186/s12977-015-0225-x

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1128/JVI.00983-15

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1038/srep12841

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：WILEY-BLACKWELL  

Ras GTPase-activating proteins negatively regulate the Ras/Erk signaling pathway, thereby playing crucial roles in the proliferation, function, and development of various types of cells. In this study, we identified a novel Ras GTPase-activating proteins protein, RASAL3, which is predominantly expressed in cells of hematopoietic lineages, including NKT, B, and Tcells. We established systemic RASAL3-deficient mice, and the mice exhibited a severe decrease in NKT cells in the liver at 8 weeks of age. The treatment of RASAL3-deficient mice with -GalCer, a specific agonist for NKT cells, induced liver damage, but the level was less severe than that in RASAL3-competent mice, and the attenuated liver damage was accompanied by a reduced production of interleukin-4 and interferon- from NKT cells. RASAL3-deficient NKT cells treated with -GalCer in vitro presented augmented Erk phosphorylation, suggesting that there is dysregulated Ras signaling in the NKT cells of RASAL3-deficient mice. Taken together, these results suggest that RASAL3 plays an important role in the expansion and functions of NKT cells in the liver by negatively regulating Ras/Erk signaling, and might be a therapeutic target for NKT-associated diseases.

DOI： 10.1002/eji.201444977

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：WILEY-BLACKWELL  

Human T-cell leukemia virus type 1 (HTLV-1) is the etiological agent of adult T cell leukemia (ATL), which is an aggressive form of T-cell malignancy. HTLV-1 oncoproteins, Tax and HBZ, play crucial roles in the immortalization of T-cells and/or leukemogenesis by dysregulating the cellular functions in the host. Recent studies show that HTLV-1-infected T-cells have reduced expression of the BCL11B tumor suppressor protein. In the present study, we explored whether Tax and/or HBZ play a role in downregulating BCL11B in HTLV-1-infected T-cells. Lentiviral transduction of Tax in a human T-cell line repressed the expression of BCL11B at both the protein and mRNA levels, whereas the transduction of HBZ had little effect on the expression. Tax mutants with a decreased activity for the NF-B, CREB or PDZ protein pathways still showed a reduced expression of the BCL11B protein, thereby implicating a different function of Tax in BCL11B downregulation. In addition, the HTLV-2 Tax2 protein reduced the BCL11B protein expression in T-cells. Seven HTLV-1-infected T-cell lines, including three ATL-derived cell lines, showed reduced BCL11B mRNA and protein expression relative to an uninfected T-cell line, and the greatest reductions were in the cells expressing Tax. Collectively, these results indicate that Tax is responsible for suppressing BCL11B protein expression in HTLV-1-infected T-cells; Tax-mediated repression of BCL11B is another mechanism that Tax uses to promote oncogenesis of HTLV-1-infected T-cells.

DOI： 10.1111/cas.12618

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1074/jbc.M114.610386

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：WILEY-BLACKWELL  

Human T-cell leukemia virus type 1 (HTLV-1), an etiological agent of adult T-cell leukemia, immortalizes and transforms primary human T cells in vitro in both an interleukin (IL)-2-dependent and IL-2-independent manner. Expression of the HTLV-1 oncoprotein Tax transforms the growth of the mouse T-cell line CTLL-2 from being IL-2-dependent to IL-2-independent. Withdrawal of IL-2 from normal activated T cells induces apoptosis, which is mediated through the inducible expression of several proapoptotic proteins, including Bim. In this study, we found that Tax protects IL-2-depleted T cells against Bim-induced apoptosis. Withdrawal of IL-2 from CTLL-2 cells induced a prominent increase in the level of Bim protein in CTLL-2 cells, but not in Tax-transformed CTLL-2 cells. This inhibition of Bim in Tax-transformed CTLL-2 cells was mediated by two mechanisms: downregulation of Bim mRNA and posttranscriptional reduction of Bim protein. Transient expression of Tax in CTLL-2 cells also inhibited IL-2 depletion-induced expression of Bim, however, this decrease in Bim protein expression was not due to downregulation of Bim mRNA, thus indicating that Bim mRNA downregulation in Tax-transformed CTLL-2 occurs only after long-term expression of Tax. Transient expression of Tax in CTLL-2 cells also induced Erk activation, however, this was not involved in the reduction of Bim protein. Knockdown of Bim expression in CTLL-2 cells augmented Tax-induced IL-2-independent transformation. HTLV-1 infection of human T cells also reduced their levels of Bim protein, and restoring Bim expression in HTLV-1-infected cells reduced their proliferation by inducing apoptosis. Taken together, these results indicate that Tax-induced downregulation of Bim in HTLV-1-infected T cells promotes their IL-2-independent growth, thereby supporting the persistence of HTLV-1 infection in vivo.

DOI： 10.1002/cam4.329

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.virol.2013.04.032

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER SOC HEMATOLOGY  

Human T-cell leukemia virus type 1 (HTLV-1) is the etiological agent of adult T-cell leukemia (ATL), and the viral oncoprotein Tax plays key roles in the immortalization of human T cells, lifelong persistent infection, and leukemogenesis. We herein identify the ubiquitin-specific protease 10 (USP10) as a Tax-interactor in HTLV-1-infected T cells. USP10 is an antistress factor against various environmental stresses, including viral infections and oxidative stress. On exposure to arsenic, an oxidative stress inducer, USP10 is recruited into stress granules (SGs), and USP10-containing SGs reduce reactive oxygen species (ROS) production and inhibit ROS-dependent apoptosis. We found that interaction of Tax with USP10 inhibits arsenic-induced SG formation, stimulates ROS production, and augments ROS-dependent apoptosis in HTLV-1-infected T cells. These findings suggest that USP10 is a host factor that inhibits stress-induced ROS production and apoptosis in HTLV-1-infected T cells; however, its activities are attenuated by Tax. A clinical study showed that combination therapy containing arsenic is effective against some forms of ATL. Therefore, these findings may be relevant to chemotherapy against ATL.

DOI： 10.1182/blood-2013-03-493718

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：WILEY-BLACKWELL  

Human T-cell leukemia virus type 1 (HTLV-1) is the etiological agent of adult T-cell leukemia (ATL). HTLV-1 encodes the oncoprotein Tax1, which is essential for immortalization of human T-cells and persistent HTLV-1 infection in vivo. Tax1 has a PDZ binding motif (PBM) at its C-terminus. This motif is crucial for the transforming activity of Tax1 to a T-cell line and persistent HTLV-1 infection. Tax1 through the PBM interacts with PDZ domain proteins such as Dlg1 and Scribble, but it has not been determined yet, which cellular PDZ proteins mediate the functions of Tax1 PBM. Here we demonstrate that Tax1 interacts with the PDZ domain protein MAGI-1 in a PBM-dependent manner, and the interaction mislocalizes MAGI-1 from the detergent-soluble to the detergent-insoluble cellular fraction in 293T cells and in HTLV-1-infected T-cells. In addition, Tax1-transformation of a T-cell line from interleukin (IL)-2-dependent to IL-2-independent growth selects cells with irreversibly reduced expression of MAGI-1 at mRNA level. These findings imply that Tax1, like other viral oncoproteins, targets MAGI-1 as a mechanism to suppress its anti-tumor functions in HTLV-1-infected cells to contribute to the transforming activity of T-cells and persistent HTLV-1 infection.

DOI： 10.1111/cas.12087

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：WILEY-BLACKWELL  

Upon exposure to various environmental stresses such as arsenite, hypoxia, and heat shock, cells inhibit their translation and apoptosis and then repair stress-induced alterations, such as DNA damage and the accumulation of misfolded proteins. These types of stresses induce the formation of cytoplasmic RNA granules called stress granules (SGs). SGs are storage sites for the many mRNAs released from disassembled polysomes under these stress conditions and are essential for the selective translation of stress-inducible genes. Ras-GTPase-activating protein SH3 domain-binding protein 1 (G3BP1) is a component of SGs that initiates the assembly of SGs by forming a multimer. In this study, we examined the role of G3BP2, a close relative of G3BP1, in SG formation. Although single knockdown of either G3BP1 or G3BP2 in 293T cells partially reduced the number of SG-positive cells induced by arsenite, the knockdowns of both genes significantly reduced the number. G3BP2 formed a homo-multimer and a hetero-multimer with G3BP1. Moreover, like G3BP1, the overexpression of G3BP2 induced SGs even without stress stimuli. Collectively, these results suggest that both G3BP1 and G3BP2 play a role in the formation of SGs in various human cells and thereby recovery from these cellular stresses.

DOI： 10.1111/gtc.12023

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER  

While human T cell leukemia virus type 1 (HTLV-1) is the causative agent of adult T cell leukemia, a close relative, HTLV-2, is not associated with any leukemia. HTLV-1 and HTLV-2 encode the Tax1 and Tax2 proteins, respectively, which are essential for the immortalization of human T cells by the respective viruses, thereby causing persistent infection. In this study, we compared Tax1 and Tax2 with respect to their immortalization activity in human T cells. Lentivirus-mediated transduction of the tax2 gene into human peripheral blood mononuclear cells stimulated with phytohemagglutinin and interleukin-2 in 96-well plates induced outgrowing T cells in most wells, but the cells infected with the control viruses died within 3 weeks. Surprisingly, the number of outgrowing cells induced by Tax2 was much higher than that induced by Tax1, and the appearance of outgrowing cells by Tax2 was earlier than that induced by Tax1. Nevertheless, both Tax2 and Tax1 preferentially immortalized CD4(+) T cells, but not CD8(+) T cells. Our study showed that HTLV-2 Tax2 can immortalize human CD4(+) T cells, and the activity is much higher than that of Tax1. The distinct T cell immortalization activities of Tax2 and Tax1 might therefore play a role in the different pathogeneses observed for these two viruses.

DOI： 10.1007/s11262-012-0831-9

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Cells can undergo two alternative fates following exposure to environmental stress: they either induce apoptosis or inhibit apoptosis and then repair the stress-induced alterations. These processes minimize cell loss and prevent the survival of cells with aberrant DNA and protein alterations. These two alternative fates are partly controlled by stress granules (SGs). While arsenite, hypoxia, and heat shock induce the formation of SGs that inhibit apoptosis, X-ray irradiation and genotoxic drugs do not induce SGs, and they are more prone to trigger apoptosis. However, it is unclear precisely how SGs control apoptosis. This study found that SGs suppress the elevation of reactive oxygen species (ROS), and this suppression is essential for inhibiting ROS-dependent apoptosis. This antioxidant activity of SGs is controlled by two SG components, GTPase-activating protein SH3 domain binding protein 1 (G3BP1) and ubiquitin-specific protease 10 (USP10). G3BP1 elevates the steady-state ROS level by inhibiting the antioxidant activity of USP10. However, following exposure to arsenite, G3BP1 and USP10 induce the formation of SGs, which uncovers the antioxidant activity of USP10. We also found that the antioxidant activity of USP10 requires the protein kinase activity of ataxia telangiectasia mutated (ATM). This work reveals that SGs are critical redox regulators that control cell fate under stress conditions. © 2013, American Society for Microbiology.

DOI： 10.1128/MCB.00763-12

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：WILEY-BLACKWELL  

Human T-cell leukemia virus type 1 (HTLV-1) is a causative agent of adult T-cell leukemia, and it immortalizes and transforms human T cells in both an interleukin (IL)-2-dependent and -independent manner. HTLV-1 encodes Tax, which plays crucial roles in HTLV-1-mediated immortalization and transformation of human T cells. A previous study showed that Tax can transform a mouse T-cell line, CTLL-2, from having IL-2-dependent growth to IL-2-independent growth. Given that the Akt/mTOR pathway is essential for IL-2-induced cell growth in T cells, we examined whether the Akt/mTOR pathway is involved in Tax-induced transformation to IL-2-independent growth. The stable and transient expression of Tax in CTLL-2 induced the phosphorylation of p70S6 kinase and ribosomal protein S6, downstream targets of the mTOR kinase, whereas that of Akt was only minimally induced. Studies with Tax mutants indicated that the activation of mTOR by Tax was correlated with the transformation of CTLL-2 cells to IL-2-independent growth. Rapamycin, an inhibitor of mTOR kinase, reduced the growth of Tax-transformed CTLL-2 cells. Moreover, the transduction of a constitutively active form of Akt in the CTLL-2 cells also induced IL-2-independent growth. Like CTLL-2/Tax, constitutive phosphorylation of p70S6 kinase was detected in the absence of IL-2 in all of the HTLV-1-infected human T-cell lines. These results suggest that Tax activates the mTOR pathway in T cells, and that this activation plays a crucial role in the growth of HTLV-1-infected T cells when a limited amount of IL-2 is available. (Cancer Sci 2012; 103: 369374)

DOI： 10.1111/j.1349-7006.2011.02123.x

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER  

Several tumor viruses, such as human T-cell leukemia virus (HTLV), human papilloma virus (HPV), human adenovirus, have high-oncogenic and low-oncogenic subtypes, and such subtype-specific oncogenesis is associated with the PDZ-domain binding motif (PBM) in their transforming proteins. HTLV-1, the causative agent of adult T-cell leukemia, encodes Tax1 with PBM as a transforming protein. The Tax1 PBM was substituted with those from other oncoviruses, and the transforming activity was examined. Tax1 mutants with PBM from either HPV-16 E6 or adenovirus type 9 E4ORF1 are fully active in the transformation of a mouse T-cell line from interleukin-2-dependent growth into independent growth. Interestingly, one such Tax1 PBM mutant had an extra amino acid insertion derived from E6 between PBM and the rest of Tax1, thus suggesting that the amino acid sequences of the peptides between PBM and the rest of Tax1 and the numbers only slightly affect the function of PBM in the transformation. Tax1 and Tax1 PBM mutants interacted with tumor suppressors Dlg1 and Scribble with PDZ-domains. Unlike E6, Tax1 PBM mutants as well as Tax1 did not or minimally induced the degradations of Dlg1 and Scribble, but instead induced their subcellular translocation from the detergent-soluble fraction into the insoluble fraction, thus suggesting that the inactivation mechanism of these tumor suppressor proteins is distinct. The present results suggest that PBMs of high-risk oncoviruses have a common function(s) required for these three tumor viruses to transform cells, which is likely associated with the subtype-specific oncogenesis of these tumor viruses.

DOI： 10.1007/s11262-009-0447-x

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記述言語：英語   出版者・発行元：BIOMED CENTRAL LTD  

While the human T-cell leukemia virus type 1 (HTLV-1) is the etiologic agent of adult T-cell leukemia/lymphoma (ATL), to date, its close relative HTLV-2 is not associated with ATL or other types of malignancies. Accumulating evidence shows that HTLV-1 Tax1 and HTLV-2 Tax2 have many shared activities, but the two proteins have a limited number of significantly distinct activities, and these distinctions appear to play key roles in HTLV-1 specific pathogenesis. In this review, we summarize the functions of Tax1 associated with cell survival, cell proliferation, persistent infection as well as pathogenesis. We emphasize special attention to distinctions between Tax1 and Tax2.

DOI： 10.1186/1742-4690-6-117

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：BIOMED CENTRAL LTD  

Background: Human T-cell leukemia virus type 1 (HTLV-1) is a causative agent of adult T-cell leukemia (ATL), whereas its relative HTLV-2 is not associated with any malignancies including ATL. HTLV-1 Tax1 transformed a T-cell line from interleukin (IL)-2-dependent growth to IL-2-independent growth, with an activity that was much more potent in comparison to HTLV-2 Tax2. This distinction was mediated by at least two Tax1 specific functions, an interaction with host cellular factors through the PDZ domain binding motif (PBM) and the activation of NF-kappaB2 (NF-kappa B2)/p100.
Results: Using a series of Tax1 chimeric proteins with Tax2, we found that amino acids 225-232 of Tax1, the Tax1(225-232) region, was essential for the activation of NF-kappa B2 as well as for the high transforming activity. The strict amino acid conservation of Tax1(225-232) among HTLV-1 and simian T-cell leukemia virus type 1 (STLV-1), but not HTLV-2 and STLV-2, indicates that function(s) through the Tax1(225-232) region are biologically significant. Interestingly, another HTLV-1 relative, HTLV-3, has a PBM, but does not conserve the Tax1(225-232) motif in Tax3, thus indicating that these two motifs classify the three HTLVs into the separate groups.
Conclusion: These results suggest that the combinatory functions through Tax1(225-232) and PBM play crucial roles in the distinct biological properties of the three HTLVs, perhaps also including their pathogenesis.

DOI： 10.1186/1742-4690-6-83

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC  

At the incipient stages of the development of adult T-cell leukemia, T-cells infected with human T-cell leukemia virus type 1 (HTLV-1) suffer disregulation in cell growth caused by aberrant expression of host genes by the HTLV-1 transactivator protein Tax (Tax1). Tax1-mediated growth promotion is thought to result from, at least in part, up-regulation of genes for growth factors and their receptors that induce T-cell growth. In the present study, we demonstrate that Tax1 transactivates the interleukin-21 (IL-21) and its receptor (IL-21R) genes in human T-cells. Introduction of Tax1 via recombinant adenoviruses induced expression of endogenous IL-21 and IL-21R. Isolated promoters of the IL-21 and IL-21R genes were activated by Tax1 in reporter assays, which further revealed that there were at least two Tax1-responsive elements in either the IL-21 promoter or the IL-21R promoter. Chromatin immunoprecipitation assay and gel mobility shift assay exhibited that the IL-21 promoter elements bound transcription factors AP-1 and NF-kappa B, and the IL-21R promoter elements were associated with AP-1 and interferon regulatory factor. Collectively, Tax1-dependent activation of these transcriptional factors presumably contributes to expression of the IL-21 gene and its receptor gene. The related virus HTLV-2 with Tax2 similar to Tax1 is known not to be pathogenic. Tax2 exhibited little, if any, or no induction of the IL-21 transcription in CD4(+) T-cells, in contrast to Tax1. The study suggests insights into cytokine-dependent aberrant growth of HTLV-1-infected T-cells and the molecular basis of different pathogenicity between HTLV-1 and HTLV-2.

DOI： 10.1074/jbc.M109.010959

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER SOC HEMATOLOGY  

Adult T-cell leukemia (ATL) is a highly aggressive T-cell malignancy caused by human T-cell leukemia virus type 1 (HTLV-1). The activation of NF-kappa B by Tax has been reported to play a crucial role in HTLV-1-induced transformation. The HTLV-1 bZIP factor (HBZ), which is encoded by an mRNA of the opposite polarity of the viral genomic RNA, is involved in both T cell proliferation and suppression of Tax-mediated viral gene transcription, suggesting that HBZ cooperates closely with Tax. In the present study, we observed that HBZ specifically suppressed NF-kappa B-driven transcription mediated by p65 (the classical pathway) without inhibiting the alternative NF-kappa B signaling pathway. In an immunoprecipitation assay, HBZ bound to p65 and diminished the DNA binding capacity of p65. In addition, HBZ induced p65 degradation through increasing the expression of the PDLIM2 gene, which encodes a ubiquitin E3 ligase for p65. Finally, HBZ actually repressed the transcription of some classical NF-kappa B target genes, such as IL-8, IL2RA, IRF4, VCAM-1, and VEGF. Selective suppression of the classical NF-kappa B pathway by HBZ renders the alternative NF-kappa B pathway predominant after activation of NF-kappa B by Tax or other stimuli, which might be critical for oncogenesis. (Blood. 2009;113:2755-2764)

DOI： 10.1182/blood-2008-06-161729

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER  

Human T-cell leukemia virus type 1 (HTLV-1) is a causative agent of adult T-cell leukemia. HTLV-1 Tax1 transforming protein interacts with several PDZ domain-containing proteins, and the interaction is associated with the transforming activities of Tax1 as well as persistent HTLV-1 infection. In this study, we show that Tax1 interacts with the tumor suppressor Scribble containing PDZ domains. Unlike other Tax1-interacting PDZ domain proteins, the PDZ domain-binding motif (PBM) of Tax1 was not required for the interaction with transiently expressed Scribble in 293T cells, but it was essential for the interaction with endogenous Scribble. Endogenous Scribble in 293T cells was primarily localized at the plasma membrane and colocalized with Tax1 but not Tax1 Delta C lacking PBM, whereas transiently expressed Scribble was localized in the cytoplasm and colocalized with Tax1 Delta C as well as Tax1, thus suggesting that Tax1 is recruited to the site of endogenous Scribble, such as the plasma membrane, in a PBM-dependent manner, and thereafter it interacts with Scribble in a PBM-independent and PBM-dependent manner. Endogenous Scribble was diffusely localized at the plasma membrane of HTLV-1-uninfected T-cell lines, whereas it colocalized with Tax1 as small and large aggregate at the plasma membranes. These results suggest that Tax1 through two binding sites induce aberrant clustering of Scribble, thereby altering the functions in HTLV-1-infected cells, which may thus play a role in persistent HTLV-1 infection and the pathogenesis.

DOI： 10.1007/s11262-008-0259-4

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER  

Human T-cell leukemia virus type 1 (HTLV-1) spreads through cell-to-cell contact by forming a virological synapse. Based on the finding that HTLV-1 envelope glycoprotein (Env) binds to a PDZ domain containing scaffold protein Dlg1, whose function has been implicated in the organization of neuronal and immunological synapses, we examined the role of Dlg1 in the cell-cell infection by HTLV-1. The coculture of an HTLV-1-infected T-cell line MT-2 with an uninfected MOLT-4 induced syncytium, a marker of cell-cell HTLV-1 infection, but an RNA interference-mediated knockdown of Dlg1 in both cells cooperatively reduced the syncytium formation. In HTLV-1-uninfected 293T cells, Dlg1 induced the clustering of GLUT1, a cellular receptor for HTLV-1, but such clustering was abrogated by a deletion of the PDZ domain binding motif of GLUT1 (GLUT1 Delta C). GLUT1 expression in MDBK cells induced HTLV-1-mediated syncytium formation, and the activity was much greater than that of GLUT1 Delta C. These results suggest that Dlg1, through the interaction with GLUT1 as well as Env, plays a positive role in the syncytium formation induced by HTLV-1.

DOI： 10.1007/s11262-008-0234-0

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：NATURE PUBLISHING GROUP  

Adult T-cell leukemia (ATL) is a mature CD4(+) T-cell malignancy etiologically associated with human T-cell leukemia virus type 1 (HTLV-1). Primary ATL cells frequently express CCR4 at high levels. Since HTLV-1 Tax does not induce CCR4 expression, transcription factor(s) constitutively active in ATL may be responsible for its strong expression. We identified an activator protein-1 (AP-1) site in the CCR4 promoter as the major positive regulatory element in ATL cells. Among the AP-1 family members, Fra-2, JunB and JunD are highly expressed in fresh primary ATL cells. Consistently, the Fra-2/JunB and Fra-2/JunD heterodimers strongly activated the CCR4 promoter in Jurkat cells. Furthermore, Fra-2 small interfering RNA (siRNA) or JunD siRNA, but not JunB siRNA, effectively reduced CCR4 expression and cell growth in ATL cells. Conversely, Fra-2 or JunD overexpression promoted cell growth in Jurkat cells. We identified 49 genes, including c-Myb, BCL-6 and MDM2, which were downregulated by Fra-2 siRNA in ATL cells. c-Myb, BCL-6 and MDM2 were also downregulated by JunD siRNA. As Fra-2, these proto-oncogenes were highly expressed in primary ATL cells but not in normal CD4(+) T cells. Collectively, aberrantly expressed Fra-2 in association with JunD may play a major role in CCR4 expression and oncogenesis in ATL.

DOI： 10.1038/sj.onc.1210984

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：BLACKWELL PUBLISHING  

Adult T-cell leukemia (ATL) is an aggressive type of leukemia, originating from T-cells infected with human T-cell leukemia virus type 1. Accumulating evidence suggests the aberrant activation of NF-kappa B to be a causative factor mediating the abnormal proliferation of leukemic cells, thus resulting in the development of ATL. A rearranged NF-kappa B2/p100 gene was isolated from an ATL-derived cell line, which was generated by a chromosomal translocation. The isolated NF-kappa B2 mutant is fused with the with no (lysine) deficient protein kinase 1 gene, coding for a 58 kDa protein that retains the DNA binding Rel homology domain, but it lacks the entire ankyrin repeat inhibitory domain, thus suggesting its constitutive activation. This rearranged NF-kappa B2 gene product (p58) was localized in the nucleus, and formed a complex with NF-kappa B p65 or RelB. Moreover, a T-cell line expressing p58 increased the amount of an NF-kappa B2-inducible gene, NF-kappa B2/p100 by itself. These results suggest that such NF-kappa B2 gene rearrangement may therefore be a factor in the constitutive activation of NF-kappa B in ATL, and thereby playing a role in the ATL pathogenesis.

DOI： 10.1111/j.1349-7006.2008.00750.x

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER SOC MICROBIOLOGY  

Human T-cell leukemia virus type 1 (HTLV-1) but not HTLV-2 is associated with adult T-cell leukemia, and the distinct pathogenicity of these two closely related viruses is thought to stem from the distinct biological functions of the respective transforming proteins, HTLV-1 Tax1 and HTLV-2 Tax2. In this study, we demonstrate that Tax1 but not Tax2 interacts with NF-kappa B2/p100 and activates it by inducing the cleavage of p100 into the active transcription factor p52. Using RNA interference methods, we further show that NF-kappa B2/p100 is required for the transformation induced by Tax1, as determined by the ability to convert a T-cell line (CTLL-2) from interleukin-2 (IL-2)-dependent to -independent growth. While Tax2 shows a reduced transforming activity relative to Tax1, Tax2 fused with a PDZ domain binding motif (PBM) present only in Tax1 shows transforming activity equivalent to that of Tax1 in CTLL-2 cells expressing an inducer of p52 processing. These results reveal that the activation of NF-kappa B2/p100 plays a crucial role in the Tax1-mediated transformation of T cells and that NF-kappa B2/p100 activation and PBM function are both responsible for the augmented transforming activity of Tax1 relative to Tax2, thus suggesting that these Tax1-specific functions play crucial roles in HTLV-1 leukemogenesis.

DOI： 10.1128/JVI.00532-07

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：CENTER DISEASE CONTROL  

Vero cells, we isolated a virus (NII561-2000) from a cerebrospinal fluid specimen of a 1-year-old girl with Reye syndrome. The determined amino acid sequence of the virus indicated that the isolate was a human parechovirus (HPeV), a member of Picornaviridae. Neutralization test showed that the NII561-2000 virus had distinct antigenicity to HPeV-1, HPeV-2, and HPeV-3, and that the sequence was distinct from these types as well as from HPeV-4 and HPeV-5. Thus, we propose the virus (NII561-2000) as the prototype of HPeV-6. We isolated 10 NII561-2000-related viruses, 14 HPeV-1, 16 HPeV-3, and 1 HPeV-4 of 41 HPeVs from various clinical samples collected in Niigata, Japan. Clinical symptoms of the persons infected with the NII5612000-related viruses were infectious gastroenteritis, rash, upper respiratory tract infection, and paralysis, in addition to Reye syndrome in the 1-year-old girl.

DOI： 10.3201/eid1306.060896

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER  

Kaposi's sarcoma-associated herpesvirus (KSHV) establishes latent infection in various cells in vitro as well as KSHV-associated tumor cells in vivo. The latency-associated nuclear antigen (LANA) of KSHV is one of a small number of genes expressed in the latent phase of KSHV infection. This antigen is crucial for establishment of the latent infection, such as replication of KSHV genomic DNA and maintenance of infection via direct interaction with terminal repeats (TRs) in the viral genome. Using a yeast two-hybrid screening method, we isolated a novel LANA-interacting protein (designated as KZLP; KRAB Zinc finger LANA Protein) from a human peripheral leukocyte cDNA library. KZLP encodes a KRAB domain and 12 Kruppel-type zinc fingers. Reverse transcription polymerase chain reaction showed that KZLP was expressed ubiquitously in various cell lines including those infected with KSHV. A luciferase assay showed that KZLP could activate the KSHV open reading frame K1 promoter containing TRs in 293T cells, and that such activation required multiple TR sequences. In contrast, LANA repressed the activity of the K1 promoter through TRs, and again this repression required multiple TR units. Moreover, LANA almost completely abrogated the KZLP-mediated transcriptional activation. Our results suggest that KZLP and LANA regulate gene expression through TRs in the KSHV viral genome, including the K1 gene in latent KSHV-infected cells.

DOI： 10.1007/s11262-006-0048-x

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：BIOMED CENTRAL LTD  

Background: While human T-cell leukemia virus type 1 (HTLV-1) is a causative agent of adult Tcell leukemia, HTLV type 2 (HTLV-2) is not associated with this malignancy. Accumulating evidence suggests that Tax, a transforming protein of HTLV-1 or HTLV-2, plays a crucial role in the distinctive pathogenesis of these two infections. We herein examined whether Tax2 by itself has a growth promoting activity in a mouse T-cell line CTLL-2, and compared the activity with that of Tax1.
Results: We found that Tax2 converts the cell growth of CTLL-2 from an interleukin(IL)-2-dependent growth into an independent one. Cyclosporine A, an inhibitor of transcription factor NFAT, inhibited the growth of two out of four Tax2-transformed CTLL-2 cells, but it had little effect on two Tax1-transformed cells. While the HTLV-2-transformed human T-cell lines produce a significant amount of IL-2, Tax2-transformed CTLL-2 cells only produced a minimal amount of IL-2. These results thus suggest that NFAT-inducible gene(s) other than IL-2 play a role in the cell growth of Tax2-transformed CTLL-2 cells.
Conclusion: These results show that HTLV-2 Tax2 by itself has a growth promoting activity toward a T-cell line CTLL-2, and the CTLL-2 assay used in this study may therefore be a useful tool for comparing the activity of Tax2 with that of Tax1 in T-cells, thereby elucidating the mechanism of HTLV-1 specific leukemogenesis.

DOI： 10.1186/1742-4690-3-88

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：BIOMED CENTRAL LTD  

Background: The interaction of human T-cell leukemia virus type 1 (HTLV-1) Tax1 protein with the tumor suppressor Dlg1 is correlated with cellular transformation.
Results: Here, we show that Dlg1 knockdown by RNA interference increases the ability of Tax1 to transform a mouse T-cell line (CTLL-2), as measured interleukin (IL)-2-independent growth. A Tax1 mutant defective for the Dlg1 interaction showed reduced transformation of CTLL-2 compared to wild type Tax1, but the transformation was minimally affected by Dlg1 reduction. The few Tax1 Delta C-transduced CTLL-2 cells that became transformed expressed less Dlg1 than parental cells, suggesting that Dlg1-low cells were selectively transformed by Tax1 Delta C. Moreover, all human T-cell lines immortalized by HTLV-1, including the recombinant HTLV-1-containing Tax1 Delta C, expressed less Dlg1 than control T-cell lines.
Conclusion: These results suggest that inactivation of Dlg1 augments Tax1-mediated transformation of CTLL-2, and PDZ protein(s) other than Dlg1 are critically involved in the transformation.

DOI： 10.1186/1742-4690-3-71

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記述言語：英語   出版者・発行元：BIOMED CENTRAL LTD  

Background: Adult T-cell leukemia (ATL) is a complex and multifaceted disease associated with human T-cell leukemia virus type I (HTLV-I) infection. Tax, the viral oncoprotein, is considered a major contributor to cell cycle deregulation in HTLV-I transformed cells by either directly disrupting cellular factors (protein-protein interactions) or altering their transcription profile. Tax transactivates these cellular promoters by interacting with transcription factors such as CREB/ATF, NF-kappa B, and SRF. Therefore by examining which factors upregulate a particular set of promoters we may begin to understand how Tax orchestrates leukemia development. Results: We observed that CTLL cells stably expressing wild-type Tax (CTLL/WT) exhibited aneuploidy as compared to a Tax clone deficient for CREB transactivation (CTLL/703). To better understand the contribution of Tax transactivation through the CREB/ATF pathway to the aneuploid phenotype, we performed microarray analysis comparing CTLL/WT to CTLL/703 cells. Promoter analysis of altered genes revealed that a subset of these genes contain CREB/ATF consensus sequences. While these genes had diverse functions, smaller subsets of genes were found to be involved in G2/M phase regulation, in particular kinetochore assembly. Furthermore, we confirmed the presence of CREB, Tax and RNA Polymerase II at the p97Vcp and SgtI promoters in vivo through chromatin immunoprecipitation in CTLL/WT cells. Conclusion: These results indicate that the development of aneuploidy in Tax-expressing cells may occur in response to an alteration in the transcription profile, in addition to direct protein interactions.

DOI： 10.1186/1742-4690-3-43

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記述言語：英語   出版者・発行元：NATURE PUBLISHING GROUP  

Human T-lymphotropic virus type 1 (HTLV-1) infection is associated with the clonal expansion and transformation of mature T lymphocytes. While the mechanisms involved are incompletely understood the viral regulatory protein Tax plays a central role in these processes. Recent studies employing genomic and proteomic approaches have demonstrated the marked complexity of gene deregulation associated with Tax expression and confirmed the remarkable pleiotropism of this protein as evidenced by the numerous Tax-cellular protein interactions in infected cells. In this review, we summarize the role of Tax in the deregulation of selected cellular-signaling pathways. Specifically, this has focused on the influence and interaction of Tax with the AP-1 and NF-AT transcription factors, PDZ domain-containing proteins, RhoGTPases, and the Janus kinase/signal transducer and activator of transcription and transforming growth factor-beta-signaling pathways. In addition to identifying the deregulation of events within these pathways, attempts have been made to highlight differences between HTLV-1 and -2, which may relate to differences in their pathogenic properties.

DOI： 10.1038/sj.onc.1208975

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER SOC MICROBIOLOGY  

Human T-cell leukemia virus type 1 (HTLV-1) but not HTLV-2 is associated with adult T-cell leukemia. We found that HTLV-2 Tax2 protein stimulated reporter gene expression regulated by the interleukin (IL)-2 promoter through the nuclear factor of activated T cells (NFAT) in a human T-cell line (Jurkat). However, the activity of HTLV-1 Tax1 was minimal in this system. T-cell lines immortalized by HTLV-2 but not HTLV-1 constitutively exhibited activated NFAT in the nucleus and constitutively expressed IL-2 mRNA. Cyclosporine A, an inhibitor of NFAT activation, abrogated the induction of IL-2 mRNA in HTLV-2-immortalized T-cell lines and concomitantly inhibited cell growth. This growth inhibition was rescued by the addition of IL-2 to the culture. Furthermore, anti-IL-2 receptor antibodies significantly reduced the proliferation of HTLV-2-infected T-cell lines but not that of HTLV-1-infected cells. Our results suggest that Tax2 activates an IL-2 autocrine loop mediated through NFAT that supports the growth of HTLV-2-infected cells under low-IL-2 conditions. This mechanism would be especially important in vivo, where this autocrine mechanism establishes a non-leukemogenic life-long HTLV-2 infection. The results also suggest that differences in long-term cytokine production between HTLV-1 and HTLV-2 infection are another factor for the differences in pathogenesis.

DOI： 10.1128/JVI.79.18.11925-11934.2005

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：BIOMED CENTRAL LTD  

Background: Human T-cell leukemia virus type 1 (HTLV-1) is the etiologic agent of adult T-cell leukemia (ATL), whereas HTLV type 2 (HTLV-2), is not associated with ATL or any other leukemia. HTLV-1 encodes the transforming gene tax1, whose expression in an interleukin (IL)-2-dependent T-cell line (CTLL-2) induces IL-2-independent growth.
Results: In this study, we demonstrated that IL-2-independent growth induction by Tax1 was abrogated by mutations of the PDZ domain-binding motif (PBM) at the Tax1 C-terminus. HTLV-2 Tax2, which shares 75% amino acid identity with Tax1 but does not have a PBM, was not able to induce IL-2-independent growth of CTLL-2.
Conclusion: Our results suggest that Tax1, through interaction with PDZ domain protein(s) induces IL-2-independent growth, which may be a factor in multi-step leukemogenesis caused by HTLV-1.

DOI： 10.1186/1742-4690-2-46

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：WILEY-LISS  

Survivin, a unique member of the inhibitor of apoptosis protein family, is overexpressed in many cancers and considered to play an important role in oncogenesis. We previously reported the survivin expression profile in ATL, a CD4-positive T-cell malignancy caused by HTLV-1. HTLV-1 Tax is thought to play an important role in immortalization of T cells. We have shown also that the expression of Tax protected the mouse T-cell line CTLL-2 against apoptosis induced by deprivation of IL-2 and converted its growth from being IL-2 dependent to being IL-2 independent through the NF-kappa B pathway. In our study, we demonstrate that constitutive expression of survivin was associated with resistance to apoptosis after IL-2 deprivation in Tax-expressing CTLL-2 cells. Transient transfection assays showed that survivin promoter was transactivated by Tax, via the activation of NF-kappa B. Pharmacological NF-kappa B inhibition resulted in suppression of survivin expression and caused apoptosis of Tax-expressing CTLL-2 cells. Our findings suggest that activated NF-kappa B signaling contributes directly to malignant progression of ATL by preventing apoptosis, acting through the prosurvival protein survivin. (c) 2005 Wiley-Liss, Inc.

DOI： 10.1002/ijc.20954

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：BIOMED CENTRAL LTD  

Background: Human T-cell leukemia virus type 1 (HTLV-1) is associated with the development of adult T-cell leukemia (ATL). HTLV-1 encoded Tax1 oncoprotein activates the transcription of genes involved in cell growth and anti-apoptosis through the NF-kappa B pathway, and is thought to play a critical role in the pathogenesis of ATL. While Tax1 expression is usually lost or minimal in ATL cells, these cells still show high constitutive NF-kappa B activity, indicating that genetic or epigenetic changes in ATL cells induce activation independent of Tax1. The aim of this study was to identify the molecules responsible for the constitutive activation of NF-kappa B in ATL cells using a retroviral functional cloning strategy.
Results: Using enhanced green fluorescent protein (EGFP) expression and blasticidin-resistance as selection markers, several retroviral cDNA clones exhibiting constitutive NF-kappa B activity in Rat-1 cells, including full-length CD30, were obtained from an ATL cell line. Exogenous stable expression of CD30 in Rat-1 cells constitutively activated NF-kappa B. Elevated expression of CD30 was identified in all ATL lines examined, and primary ATL cells from a small number of patients (8 out of 66 cases).
Conclusion: Elevated CD30 expression is considered one of the causes of constitutive NF-kappa B activation in ATL cells, and may be involved in ATL development.

DOI： 10.1186/1742-4690-2-29

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER  

Epstein-Barr virus (EBV) infection is associated with salivary gland lymphoepithelial carcinoma (SLEC) and nasopharyngeal carcinoma (NPC). EBV is a ubiquitous herpes virus world wide, but EBV-associated SLEC and NPC are prevalent in restricted regions such as south areas of China, Southeastern Asia and Greenland ( Eskimos). To examine whether particular EBV variants play roles in the development of SLEC and NPC, we isolated the complete EBV LMP1 genes from 12 paraffin-embedded biopsy samples of SLECs isolated from China, Taiwan and Russia, and compared these LMP1 genes with those of NPC (CAO) and the prototype B95-8 EBV. Nucleotide sequence analysis showed that SLECs LMP1 is more similar to that of CAO than that of prototype B95-8. The analysis also identified several conserved ( 67 - 100%) variations in SLEC-LMP1 and CAO-LMP1 distinct from B95-8-LMP1. These included 10-amino acid deletion, 5-amino acid deletion and 12-single amino acid variations. A SLEC- LMP1 gene with the aforementioned conserved variations inhibited the growth of an embryonic kidney cell line (293T), highly activated the NF-kappaB pathway, and these activities were equivalent to those of B95-8 and CAO. These findings suggest that the biological functions of SLEC-LMP 1 are similar to those of B95-8-LMP1 and CAO-LMP1, and that these amino acid variations including the well-known 10-aa deletion did not affect these two prominent activities. While the present results could not uncover functional differences between SLEC- LMP1 and B95-8-LMP1, the nucleotide sequences and the molecular clone of LMP1 directly isolated from SLEC patients will be a useful tool to identify the high-pathogenic EBV strain(s), associated with SLEC and NPC.

DOI： 10.1007/s11262-004-5630-5

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD  

In a previous study, we described the structure-activity relationships (SARs) for a series of thiazolidenebenzenesulfonamide derivatives. These compounds were found to be highly potent inhibitors of the wild type (WT) and Y181C mutant reverse transcriptases (RTs) and modest inhibitors of K 103N RT. These molecules are thus considered to be a novel class of non-nucleoside HIV-1 RT inhibitors (NNRTIs). In this paper, we have examined the effects of substituents on both the thiazolidene and benzenesulfonamide moieties. Introduction of a 2-cyanophenyl ring into these moieties significantly enhanced anti-HIV-1 activity, whereas a 2-hydroxyphenyl group endowed potent activity against RTs, including K103N and Y181C mutants. Among the series of molecules examined, 101 and 18b (YM-228855), combinations of 2-cyanophenyl and 4-methyl-5-isopropylthiazole moieties, showed extremely potent anti-HIV-1 activity. The EC50 values of 101 and 18b were 0.0017 and 0.0018 muM, respectively. These values were lower than that of efavirenz (3). Compound 11g (YM-215389), a combination of 2-hydroxyphenyl and 4-chloro-5-isopropylthiazole moieties, proved to be the most active against both K103N and Y181C RTs with IC50 values of 0.043 and 0.013 muM, respectively. (C) 2004 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.bmc.2004.11.045

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その他リンク： http://orcid.org/0000-0002-0473-754X

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：KLUWER ACADEMIC PUBL  

The latency-associated nuclear antigen ( LANA) of Kaposi's saroma-associated herpesvirus ( KSHV) can maintain a plasmid containing the KSHV origin of DNA replication (oriP) as episomes in dividing human cells. Hence, LANA is considered to play crucial roles in persistent KSHV infection in human cells. In this study, we characterized a LANA fusion protein of green fluorescent protein (GFP-LANA). Like the wild-type LANA, GFP-LANA interacted tightly with mitotic chromosomes, and maintained the plasmid selectively with the KSHV oriP for more than three weeks in a human B cell line. Moreover, equivalent amount of GFP-LANA protein was segregated into two daughter cells in living metaphase cells. Our results suggested that the activity of LANA serves the segregation of equivalent amounts of viral genomes tethered with LANA into two daughter progeny cells during cell division. Thus, GFP-LANA is a useful tool for the analyses of the functions and dynamics of LANA in living cells.

DOI： 10.1023/B:VIRU.0000036377.48454.d8

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ACADEMIC PRESS INC ELSEVIER SCIENCE  

Human T-cell leukemia virus type 1 (HTLV-1) is the causative agent of adult T-cell leukemia (ATL), whereas the closely related virus HTLV-2 has not been associated with such malignant conditions. HTLV-1 Tax1 oncoprotein transforms a rat fibroblast cell line (Rat-1) much more efficiently than does HTLV-2 Tax2. By using a differential display analysis, we isolated MAGI-3 as a Tax1-inducible gene in Rat-1 cells. Reverse transcription-polymerase chain reaction (RT-PCR) analysis confirmed that Tax1 induced MAGI-3 in Rat-1 cells. MAGI-3 has multiple PDZ domains and interacted with Tax1 but not Tax2 in 293 T cells. The interaction of Tax1 with MAGI-3 was dependent on a PDZ domain-binding motif, which is missing in Tax2. The interaction of Tax1 with MAGI-3 altered their respective subcellular localization, and moreover, the interaction correlated well with the high transforming activities of Tax1 in Rat-1 cells relative to Tax2. MAGI-3 mRNA and the allied MAGI-1, but not MAGI-2, were expressed in HTLV-1-infected T-cell lines. Our results suggest that the interaction of Tax1 and MAGI-3 alters their respective biological activities, which may play a role in transformation by Tax1 as well as in the pathogenesis of HTLV-1-associated diseases. (C) 2004 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.virol.2003.11.014

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ACADEMIC PRESS INC ELSEVIER SCIENCE  

While human T-cell leukemia virus type 1 (HTLV-1) is associated with the development of adult T-cell leukemia (ATL), HTLV-2 has not been reported to be associated with such malignant leukemias. HTLV-1 Tax1 oncoprotein transforms a rat fibroblast cell line (Rat-1) to form multiple large colonies in soft agar, and this activity is much greater than that of HTLV-2 Tax2. We have demonstrated here that the increased number of transformed colonies induced by Tax 1 relative to Tax2 was mediated by a PDZ domain-binding motif (PBM) in Tax1, which is absent in Tax2. Taxi PBM mediated the interaction of Tax1 with the discs large (Dlg) tumor suppressor containing PDZ domains, and the interaction correlated well with the transforming activities of Tax1 and the mutants. Through this interaction, Taxi altered the subcellular localization of Diu from the detergent-soluble to the detergent-insoluble fraction in a fibroblast cell line as well as in HTLV-1-infected T-cell lines. These results suggest that the interaction of Tax1 with PDZ domain protein(s) is critically involved in the transforming activity of Tax1, the activity of which may be a crucial factor in malignant transformation of HTLV-1-infected cells in vivo. (C) 2003 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.virol.2003.10.006

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：KLUWER ACADEMIC PUBL  

Kaposi's sarcoma-associated herpesvirus (KSHV)/human herpes virus type 8 (HHV-8) is tightly linked to the development of Kaposi's sarcoma, primary effusion lymphoma (PEL) and some cases of multicentric Castleman's disease. Latency-associated nuclear antigen (LANA) is one of a limited number of KSHV genes consistently expressed in these diseases as well as in KSHV-infected cell lines derived from PEL, and has been shown to play crucial role in persistence of KSHV genomes in the infected cells. In this study, we explored the cellular factors that interact with LANA using yeast two-hybrid screening, and isolated a part of gene encoding human myeloid cell nuclear differentiation antigen (MNDA). MNDA is a hematopoietic interferon-inducible nuclear proteins with a HIN-200 family member with conserved 200-amino acid repeats. Immunoprecipitation assay revealed that LANA interacted with MNDA in a mammalian embryonic kidney cell line. MNDA transcript was undetectable in three PEL cell lines by reverse-transcription polymerase chain reaction, but it was induced by interferon alpha (IFNalpha). Moreover, LANA and MNDA were co-localized in the nuclei of MNDA-expressing PEL cells. Our results suggest that LANA interacts with MNDA in KSHV-infected cells exposed to IFNalpha. Such interaction may modulate IFN-mediated host defense activities.

DOI： 10.1023/A:1026391715071

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER SOC MICROBIOLOGY  

We established a novel experimental model for human T-cell leukemia virus type 1(HTLV-1)-induced tumor using NOD-SCID/gammac(null) (NOG) mice. This model is very useful for investigating the mechanism of tumorigenesis and malignant cell growth of adult T-cell leukemia (ATL)/lymphoma, which still remains unclear. Nine HTLV-1-infected cell lines were inoculated subcutaneously in the postauricular region of NOG mice. As early as 2 to 3 weeks after inoculation, seven cell lines produced a visible tumor while two transformed cell lines failed to do so. Five of seven lines produced a progressively growing large tumor with leukemic infiltration of the cells in various organs that eventually killed the animals. Leukemic cell lines formed soft tumors, whereas some transformed cell lines developed into hemorrhagic hard tumors in NOG mice. One of the leukemic cell lines, ED-40515(-), was unable to produce visible tumors in NOD-SCID mice with a common gamma-chain after 2 weeks. In vivo NF-kappaB DNA binding activity of the ED-40515(-) cell line was higher and the NF-kappaB components were changed compared to cells in vitro. Bay 11-7082, a specific and effective NF-kappaB inhibitor, prevented tumor growth at the sites of the primary region and leukemic infiltration in various organs of NOG mice. This in vivo model of ATL could provide a novel system for use in clarifying the mechanism of growth of HTLV-1-infected cells as well as for the development of new drugs against ATL.

DOI： 10.1128/JVI.77.9.5286-5294.2003

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：JAPAN SCIENTIFIC SOC PRESS  

Adult T-cell leukemia (ATL) is a fatal T-lymphoproliferative disorder, and its development is associated with infection by human T-cell leukemia virus type I (HTLV-I). Several studies have suggested that aberrant transcription of cellular genes in HTLV-I infected cells plays a key role in the development of the disease. For instance, two transcription factors, nuclear factor kappa B (NF-kappaB)/Rel and activating protein-1 (AP-1), are transiently activated in normal T cells by growth-signals, whereas they are constitutively activated in HTLV-I infected T cells in vitro as well as in vivo. The HTLV-I oncoprotein Tax is responsible for the activation of NF-kappaB/Rel and AP-1 in HTLV-T transformed T-cell lines, and it induces a variety of cellular genes through NF-kappaB/Rel and AP-1. Unlike HTLV-I transformed T-cell lines, leukemic cells of ATL patients express extremely low levels of Tax protein, but NF-kappaB/Rel and AP-1 in leukemic cells are constitutively activated. Thus, the aberrant activation of NF-kappaB/Rel and AP-1 may be a key factor underlying the prolonged survival and proliferation of HTLV-I infected T cells both at the initial and late stages of leukemogenesis, although the mechanisms are different. In this review, we discuss the involvement of NF-kappaB/Rel and AP-1 in Tax-dependent and independent steps of leukemogenesis, and their role as potential therapeutic targets for treatment of ATL.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER SOC MICROBIOLOGY  

Latency-associated nuclear antigen 1 (LANA1) of Kaposi's sarcoma-associated herpesvirus (KSHV; human herpesvirus 8) persistently maintains a plasmid containing the KSHV latent origin of replication (oriP) as a closed circular episome in dividing cells. In this study, we investigated the involvement of chromosome binding activity of LANA1 in persistent episome maintenance. Deletion of the N-terminal 22 amino acids of LANA1 (DeltaN-LANA) inhibited the interaction with mitotic chromosomes in a human cell line, and the mutant concomitantly lost activity for the long-term episome maintenance of a plasmid containing viral oriP in a human B-cell line. However, a chimera of DeltaN-LANA with histone H1, a cellular chromosome component protein, rescued the association with mitotic chromosomes as well as the long-term episome maintenance of the oriP-containing plasmid. Our results suggest that tethering of KSHV episomes to mitotic chromosomes by LANA1 is crucial in mediating the long-term maintenance of viral episomes in dividing cells.

DOI： 10.1128/JVI.76.24.12917-12924.2002

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ACADEMIC PRESS INC ELSEVIER SCIENCE  

Cell-cell adhesion is involved in the processes of cell growth, activation and migration, and inflammation. T cells infected with human T cell leukemia virus type 1 (HTLV-1) exhibit a high degree of homotypic cell-cell adhesion in vitro. In this study, we investigated the involvement of the viral protein Tax in such process. Expression of Tax in an interleukin (IL)-2-dependent mouse T cell line (CTLL-2) increased homotypic cell-cell adhesion; however, less cell adhesion was induced by Tax than that observed in HTLV-1-infected T cell lines. Moreover, Tax induced cell-cell adhesion in a human T cell line, in which the expression of Tax is inducible. Microscopic examination also revealed Tax-induced morphologic changes, including rounding of CTLL-2 cells, increased cell volume, and increased nucleus size. Taken together, our results suggest that Tax induces cell-cell adhesion and morphologic changes in HTLV-1-infected cells. Tax may thus play a role in persistent HTLV-1 infection and the pathogenesis of associated disease. (C) 2002 Elsevier Science (USA).

DOI： 10.1006/viro.2002.1629

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER SOC HEMATOLOGY  

Human T-cell leukemia virus type I (HTLV-I) Is the causative agent of an aggressive form of leukemia designated adult T-cell leukemia (ATL). We have previously demonstrated that all T-cell lines Infected with HTLV-I and primary leukemic cells from ATL patients display constitutively high activity of transcription factor NF-B-K. In this study we showed that Bay 11-7082, an Inhibitor of NF-KB, Induced apoptosis of HTLV-I-infected T-cell lines but only negligible apoptosis of HTLV-I-negative T cells. Bay 11-7082 rapidly and efficiently reduced the DNA binding of NF-KB In HTLV-I-infected T-cell lines and down-regulated the expression of the antiapoptotic gene, Bcl-x(L), regulated by NF-KB, whereas It had little effect on the DNA binding of another transcription factor, AP-1. Although the viral protein Tax Is an activator of NF-KB, Bay 11-7082-induced apoptosis of HTLV-I-infected cells was not associated with reduced expression of Tax. Furthermore, Bay 11-7082-induced apoptosis of primary ATL cells was more prominent than that of normal peripheral blood mononuclear cells, and apoptosis of these cells was also associated with down-regulation of NF-KB activity. Our results Indicate that NF-KB plays a crucial role In the pathogenesis and survival of HTLV-I-infected leukemic cells and that It Is a suitable target for the prevention and treatment of ATL.

DOI： 10.1182/blood-2002-01-0151

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：WILEY-LISS  

Our aim was to examine the involvement of G 1 cell-cycle regulators in cell growth dysregulation induced by HTLV-1. Compared to uninfected cells, higher expression levels of cyclin D1 and D2 mRNA were detected in HTLV-1-infected T-cell lines, which were at least in part mediated by the viral transforming protein Tax since Tax activated both cyclin D I and D2 promoters in the human T-cell line jurkat. A Tax mutant that did not activate NF-kappaB failed to activate cyclin D I and D2 promoters. Inhibitors of NF-kappaB (dominant negative IkappaBs mutants) suppressed Tax-dependent activation of cyclin D1 and D2 promoters, indicating that Tax-induced activation was mediated by NF-kappaB. Wild-type and mutant Tax capable of activating NF-kappaB, but not Tax mutant incapable of activating NF-kappaB, converted cell growth of a T-cell line from being IL-2-dependent to being IL-2-independent; and this conversion was associated with IL-2-independent induction of cyclins D I and D2. Our data suggest that induction of cyclins D I and D2 by Tax is involved in IL-2-independent cell-cycle progression as well as IL-2-independent transformation of primary human T cells by HTLV-1. High expression levels of cyclin D1 and D2 mRNAs were also detected in some patients with ATL. Our findings link HTLV-1 infection to changes in cellular D-type cyclin gene expression, transformation of T cells and subsequent development of T-cell leukemia. (C) 2002 Wiley-Liss, Inc.

DOI： 10.1002/ijc.10388

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER SOC MICROBIOLOGY  

Human T-cell leukemia virus type I (HTLV-1) and HTLV-2 are retroviruses with similar biological properties. Whereas HTLV-1 is the causative agent of an aggressive T-cell leukemia, HTLV-2 has been associated with only a few cases of lymphoproliferative disorders. Taxi and Tax2 are the transcriptional activators of HTLV-1 and HTLV-2, respectively. Here we show that Tax2 transformed a Rat-1 fibroblast cell line to form colonies in soft agar, but the size and number of the colonies were lower than those of Taxi. Use of a chimeric Tax protein showed that the C-terminal amino acids 300 to 353 were responsible for the high transforming activity of Taxi. Activation of cellular genes by Taxi through transcription factor NF-kappaB is reportedly essential for the transformation of Rat-1 cells. Tax2 also activated the transcription through NF-kappaB in Rat-1 cells, and such activity was equivalent to that induced by Taxi. Thus, the high transforming activity of Taxi is mediated by mechanisms other than NF-kappaB activation. Our results showed that Tax2 has a lower transforming activity than Taxi and suggest that the high transforming activity of Taxi is involved in the leukemogenic property of HTLV-1.

DOI： 10.1128/JVI.76.6.2648-2653.2002

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：MOSBY, INC  

A case of Castleman's disease occurring in the buccal mucosa is described. An 84-year-old woman noticed that a mass in the left buccal mucosa that had been present for half a year. Computed tomography revealed a well-demarcated submucosal tumor, measuring 4.0 x 3.0 x 2.0 cm. The patient received no treatment at this time, and continued growth of the mass was observed. After incisional biopsy, the lesion was surgically removed. Histologically, the tumor consisted of an enlarged lymph node with conspicuous lymph follicles, in which vascular channels and deposits of eosinophilic material were noted. Laboratory examination showed an increase of serum antibody level of cytomegalovirus but of no other viruses. The patient was followed up for 11/2 years, with no clinical evidence of recurrence. This is the first report of Castleman's disease presenting in an oral site.

DOI： 10.1067/moe.2002.120026

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER SOC MICROBIOLOGY  

Human T-cell leukemia virus type I (HTLV-1) and HTLV-2 are retroviruses with similar biological properties. Whereas HTLV-1 is the causative agent of an aggressive T-cell leukemia, HTLV-2 has been associated with only a few cases of lymphoproliferative disorders. Taxi and Tax2 are the transcriptional activators of HTLV-1 and HTLV-2, respectively. Here we show that Tax2 transformed a Rat-1 fibroblast cell line to form colonies in soft agar, but the size and number of the colonies were lower than those of Taxi. Use of a chimeric Tax protein showed that the C-terminal amino acids 300 to 353 were responsible for the high transforming activity of Taxi. Activation of cellular genes by Taxi through transcription factor NF-kappaB is reportedly essential for the transformation of Rat-1 cells. Tax2 also activated the transcription through NF-kappaB in Rat-1 cells, and such activity was equivalent to that induced by Taxi. Thus, the high transforming activity of Taxi is mediated by mechanisms other than NF-kappaB activation. Our results showed that Tax2 has a lower transforming activity than Taxi and suggest that the high transforming activity of Taxi is involved in the leukemogenic property of HTLV-1.

DOI： 10.1128/JVI.76.6.2648-2653.2002

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記述言語：日本語   出版者・発行元：日本ウイルス学会  

DOI： 10.2222/jsv.52.281

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ACADEMIC PRESS INC  

Human T-cell leukemia virus type I (HTLV-I) Tax protein induces the expression of various family members of the transcription factor AP-I, such as c-Jun, JunD, c-Fos, and Fra-1, at the level of RNA expression in T cells. We examined the activity of Tax in transcription through AP-1-binding sites (AP-1 site) in T cells. Transient transfection studies showed that Tax activated the expression of a luciferase gene regulated by two copies of an AP-1 site in the human Jurkat T-cell line. Tax activates the expression of viral and cellular genes through two different enhancers: a cAMP-responsive (CRE)-like element and a KB element. Two Tax mutants differentially activated expression of these two elements. Tax703 preferentially activated the KB element but not the CRE-like one, whereas TaxM22 showed the reverse. In addition, Tax703 and Tax, but not TaxM22, converted cell growth of a mouse T-cell line from being interleukin (IL)-2-dependent to being Ii-a-independent. Unlike the wild-type Tax, Tax703 and TaxM22 only weakly activated the AP-1 site in the T-cell line. Thus, Tax seems to activate the AP-1 site via mechanisms distinct from those of KB Or CRE-like elements, and the activation of the AP-1 site is dispensable for IL-2-independent growth of CTLL-2. Electrophoretic mobility shift assays showed that Tax induced strong binding activity to an AP-1 site in CTLL-2, whereas Tax703 did not, indicating that the induction of binding activity to the AP-1 site is essential for the transcriptional activation by Tax. The binding complex induced by Tax in CTLL-2 contained JunD and Fra-2. Other AP-1 proteins were undetectable. Activation of transcription through the AP-1 site in Jurkat cells by JunD and/or Fra-2 was weak. c-Jun, JunB, and c-Fos activation was greater, although the level was still less than that with Tax. Thus, the induction of AP-1 mRNA by Tax may not be sufficient for a complete activation of AP-1 site by Tax. Our results suggest that Tax activates the transcription of cellular genes with AP-1 sites by inducing the DNA-binding activity of AP-1 proteins in T cells. a mechanism distinct from those of CRE-like and KB elements. (C) 2001 Academic Press.

DOI： 10.1006/viro.2000.0669

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：KLUWER ACADEMIC PUBL  

Human T-cell leukemia virus type I (HTLV-I) is the etiologic agent of adult T-cell leukemia (ATL), which is an aggressive form of human T-cell malignancy. The viral protein, Tax, immortalizes human T-cells and inhibits various types of apoptosis, and is thought to play crucial roles in the development of ATL. We have recently demonstrated that Tax induces the constitutive expression of the anti-apoptotic protein, Bcl-x(L), in a mouse T-cell line. The mouse, however, is not a natural host of HTLV-I, and HTLV-I does not induce this malignancy in mice. We thus examined whether Tax also activates the expression of Bcl-x(L) in human T-cells. Expression of Tax in a human T-cell line, Jurkat, induced the expression of the Bcl-x(L) gene, but did not significantly affect the expression of the other apoptosis-related genes, Bcl-2 and Bax. Transient transfection assays showed that Tax stimulated human Bcl-x(L) promoter activity in Jurkat cells. Deletion of the two potential nuclear factor (NF)-kappaB binding sites in the human Bcl-x(L) promoter significantly decreased Tax-induced transactivation. In addition to NF-kappaB, Tax activates transcription through the c-AMP responsive element binding protein (CREB). Tax mutants segregating these two pathways showed that both the NF-kappaB and CREB pathways of Tax are required for maximum activation of a human Bcl-x(L) promoter, nevertheless, NF-kappaB alone was sufficient for that of a mouse Bcl-x(L) promoter. Northern blot analysis showed that all the human T-cell lines expressing Tax had higher levels of Bcl-x(L) mRNA than HTLV-I-uninfected ones. Furthermore, the sample from one patient with ATL expressed higher levels of Bcl-x(L) mRNA compared with levels from uninfected peripheral blood mononuclear cells. Our results suggest that Tax induces the expression of Bc-x(L) through the NF-kappaB and CREB pathways in HTLV-I-infected human T-cells, and then inhibits apoptosis, and such inhibition is necessary for the infected cells to advance to the leukemia in vivo.

DOI： 10.1023/A:1011158021749

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：KLUWER ACADEMIC PUBL  

Human T-cell leukemia virus type 1 (HTLV-1) is an etiologic agent of adult T-cell leukemia. HTLV-1 is exclusively detected in CD45RO+ T-cells in infected individuals, but CD45RO is weakly expressed in HTLV-1-transformed T-cell lines in vitro. The aim of this study was to investigate the role of CD45RO in the persistent HTLV-1 infection in vivo. Flow cytometry showed that only two out of eight interleukin(IL)-2-independent HTLV-1-transformed T-cell lines expressed CD45RO, whereas all five IL-2-dependent ones expressed CD45RO, and the level of expression was higher in IL-2-dependent than in IL-2-independent cells. The high CD45RO expression in IL-2-dependent cell lines was not due to IL-2, since IL-2 had little effect on the expression of CD45RO in T-cell lines. Using western blotting, we showed that IL-2-dependent HTLV-1-transformed T-cell lines expressed a lower level of expression of the viral transcriptional regulatory protein Tax than IL-2-independent ones, and that the level of expression correlated inversely with that of CD45RO. However, the expression of Tax in one HTLV-1-negative T-cell line little affected the expression of CD45RO, suggesting that Tax at least alone does not suppress the expression of CD45RO in HTLV-1-infected T-cell lines, and that other viral or cellular factor(s) are probably involved in such suppression. Our results suggest that CD45RO+ Tax-low IL-2-dependent T-cell lines in vitro correspond to the persistent HTLV-1-infected cells in vivo, and HTLV-1-infected cells in vivo are immortalized in IL-2-dependent manner.

DOI： 10.1023/A:1012565105098

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

A sandwich enzyme-linked immunosorbent assay (ELISA) using rabbit anti-hepatocyte growth factor (HGF) IgG for human HGF, also known as the scatter factor, has previously been developed for determining increases in serum HGF levels in various liver diseases. The sensitivity limit of the ELISA is, however, approximately 0.2 ng/ml sample, and HGF concentrations in about 50% of normal subjects are not accurately measurable by this method, because the mean level of HGF in normal serum is close to the sensitivity limit. In the present study, chicken Fab' from egg yolk anti-HGF immunoglobulin Y and rabbit Fab' from rabbit anti-HGF Ige were conjugated with beta -D-galactosidase. With these conjugates as the second antibodies, we developed two sandwich ELISAs for human HGF and found that the sensitivities were about 20 pg/ml with the former conjugate and 2, pg/ml with the latter. The HGF concentration in sera from 138 normal subjects determined by the ELISA with the rabbit conjugate was 244+/-65 (SD) pg/ml serum, and it correlated very well with the number of leukocytes. Moreover, the ELISA with the rabbit conjugate permitted the determination of HGF levels in urine from normal subjects without first concentrating the sample. The determination of HGF in various biological fluids other than blood and urine by these ELISAs may aid the diagnosis and prognosis of various diseases. (C) 2000 Elsevier Science B.V. All rights reserved.

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER SOC MICROBIOLOGY  

Human T-cell leukemia virus type 1 (HTLV-1) is the etiologic agent for adult T-cell leukemia/lymphoma (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis. Tax(1) is a 40-kDa phosphoprotein, predominantly localized in the nucleus of the host cell, which functions to transactivate both viral and cellular promoters. It seems likely that HTLV-1, through expression of the viral regulatory protein Tax(1), provides some initial alteration in cell metabolism predisposing the development of ATL. Here, we demonstrate that HTLV-1 infection in T-cell lines and patient samples causes overexpression of an early G(1) cyclin, cyclin D2. The transcriptional up-regulation of the cyclin D2 gene is due to activation of Tax on the cyclin D2 gene. More important, we find that overexpression of cyclin D2 is accompanied by acquisition of new partners such as cyclin-dependent kinase 2 (cdk2), cdk4, and cdk6 in infected cells, This is in contrast to uninfected T cells, where cyclin D2 associates only with cdk6, Functional effects of these cyclin-cdk complexes in infected cells are shown by hyperphosphorylation of Rb and histone H1, indicators of active progression into S phase as well as changes in cellular chromatin and transcription machinery. These studies link HTLV-1 infection with changes of cellular cyclin gene expression, hence providing clues to development of T-cell leukemia.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER SOC MICROBIOLOGY  

Human T-cell leukemia virus type 1 (HTLV-1) Tax is thought to play a pivotal role in immortalization of T cells. We have recently shown that the expression of Tax protected the mouse T-cell line CTLL-2 against apoptosis induced by interleukin-2 (IL-2) deprivation and converted its growth from being IL-2 dependent to being IL-2 independent. In this study, we demonstrate that constitutive expression of bcl-xl but not bcl-2, bcl-xs, bak, bad, or bar was associated with apoptosis resistance after IL-2 deprivation in CTLL-2 cells that expressed Tax. Transient-transfection assays showed that bcl-x promoter was transactivated by wild-type Tax. Similar effects were observed in mutant Tax retaining transactivating ability through NF-kappa B. Deletion or substitution of a putative NF-kappa B binding site identified in the bcl-x promoter significantly decreased Tax-induced transactivation. This NF-kappa B-like element was able to form a complex with NF-kappa B family proteins in vitro. Furthermore, Tax-induced transactivation of the bcl-x promoter was also diminished by the mutant I kappa B alpha, which specifically inhibits NF-kappa B activity. Our findings suggest that constitutive expression of Bcl-x(L) induced by Tax through the NF-kappa B pathway contributes to the inhibition of apoptosis in CTLL-2 cells after IL-2 deprivation.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：STOCKTON PRESS  

Human T-cell leukemia virus type 1 (HTLV-1) Tax transforms normal T-cells in the presence of interleukin (IL)-2 in vitro. STAT is a family of transcription factors that play a pivotal role in cytokine-induced functions of a various type of cells. We investigated the involvement of STATs in the transformation of T-cells by HTLV-1, HTLV-1-transformed T-cell lines expressed higher amounts of STAT1, STAT3 and STAT5 RNA and proteins than virus-negative T cells. The expression of STAT1 and STAT5 in a human T-cell line was induced by Tax, IL-2 induced the DNA binding activity of STAT3 and STAT5 of a HTLV-1-transformed cell line and then stimulated its proliferation. In contrast, IL-2 did neither in a cell line lacking STAT3 and STAT5. The expression of STAT1, STAT3 and STAT5 mRNAs were also induced by a T-cell mitogen in normal human peripheral blood mononuclear cells, Our results suggest that the induction of STAT1 and STAT5 by Tax enhances cytokine-induced functions of virus-infected T-cells, hence the induction may play a role in IL-2-dependent transformation steps of T-cells by HTLV-1.

DOI： 10.1038/sj.onc.1202608

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER SOC MICROBIOLOGY  

Human T-cell leukemia virus type 1 (HTLV-1) is the etiologic agent of adult T-cell leukemia. Tax, the viral protein, is thought to be crucial in the development of the disease; since it transforms healthy T cells in vitro and induces tumors in transgenic animals. We examined the effect of Tax activity on the growth of the interleukin-2 (IL-2)-dependent T-cell line CTLL-2. Stable expression of Tax in CTLL-2 transformed cell growth from being IL-2 dependent to IL-2 independent. Tax stimulated transcription through NF-kappa B and the cyclic AMP-responsive element-like sequence in the HTLV-1 promoter. The finding of Tax mutants segregating these two pathways suggested that the NF-kappa B pathway was essential for IL-2-independent growth of CTLL-2 cells while the CRE pathway was unnecessary. However, both pathways were necessary for another transformation-related activity (colony formation in soft agar) of CTLL-2/Tax. Our results show that Tax has at least two distinct activities on T cells, and suggest that Tax plays a crucial role in IL-2-independent T-cell transformation induced by HTLV-1, in addition to its well-known IL-2-dependent cell transformation.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SOC GENERAL MICROBIOLOGY  

CD8(+) T lymphocytes of asymptomatic human immunodeficiency virus type 1 (HIV-1) carriers (ACs) are capable of suppressing HIV-1 replication in CD4(+) peripheral blood mononuclear cells (PBMC) by a variety of known and unknown mechanisms. In the present study, cell contact-dependent, major histocompatibility complex type I (MHC I)-unrestricted, CD8(+) cell-mediated suppression of HIV-1 LAI replication was detected. CD8+ PBMC of ACs suppressed HIV-1 replication more efficiently in MHC I-matched CD4(+) PBMC than in mismatched cells. However, even when MHC I was totally mismatched, CD8(+) cells still suppressed replication to a considerable extent in CD4(+) PBMC, This MHC I-unrestricted, CD8(+) cell-mediated HIV-1 suppression required cell contact and was not effective against cells of the established T cell line ILT-KK, In contrast, MHC I-restricted HIV-1 suppression by CD8(+) T cells was detected when ILT-KK cells were used as a target. By using these systems, we examined MHC I-restricted and -unrestricted suppressive activities of CD8(+) cells in various donors in more detail. Although both types of CD8(+) cell-mediated HIV-1 suppression diminished at the advanced stage of the infection, MHC I-unrestricted suppression diminished earlier than MHC I-restricted suppression, in parallel with the decline in CD4(+) T cells. These results suggest that suppression by the MHC I-restricted mechanism alone may fail to protect against CD4(+) T-cell loss at the late stage of infection.

DOI： 10.1099/0022-1317-80-1-209

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Human T-cell leukemia virus type 1 (HTLV-1) is the etiologic agent of adult T-cell leukemia. Tax, the viral protein, is thought to be crucial in the development of the disease, since it transforms healthy T cells in vitro and induces tumors in transgenic animals. We examined the effect of Tax activity on the growth of the interleukin-2 (IL-2)-dependent T-cell line CTLL-2. Stable expression of Tax in CTLL-2 transformed cell growth from being IL-2 dependent to IL-2 independent. Tax stimulated transcription through NF- κB and the cyclic Amp-responsive element-like sequence in the HTLV-1 promoter. The finding of Tax mutants segregating these two pathways suggested that the NF-κB pathway was essential for IL-2-independent growth of CTLL-2 cells while the CRE pathway was unnecessary. However, both pathways were necessary for another transformation-related activity (colony formation in soft agar) of CTLL-2/tax. Our results show that Tax has at least two distinct activities on T cells, and suggest that Tax plays a crucial role in IL-2- independent T-cell transformation induced by HTLV-1, in addition to its well- known IL-2-dependent cell transformation.

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Human T-cell leukemia virus type 1 (HTLV-1) causes T-cell malignancies in a small percentage of the population infected with the virus after a long carrier state. In the present study, we established a seronegative HTLV-1 carrier state in rats inoculated with a newly established HTLV-1-infected rat T cell line, FPM1. FPM1 originated from rat thymocytes cocultured with a human HTLV-1 producer, MT-2 cells, and expressed rat CD4, CD5, CD25, and HTLV-1 Tax. However, FPM1 scarcely expressed other major HTLV-1 structural proteins and failed to induce typical antibody responses against HTLV-1 in inoculated rats. In contrast, control rats inoculated with MT-2 cells generated significant levels of anti-HTLV-1 antibodies. HTLV-1 proviruses were detected in peripheral blood cells of syngeneic rats inoculated with FPM1 for more than 1 year. Analysis of the flanking region of HTLV-1 provirus integrated into host cells suggested that FPM1 cells remained in these animals over a relatively long period of time. However, a similar seronegative HTLV-1 carrier state was induced in the rats inoculated with mitomycin C-treated FPM1 cells and also in FPM1-inoculated allogeneic rats, suggesting that FPM1 could also transmit HTLV-1 into host cells in vivo. Our findings indicated that (i) HTLV-1-immortalized T cells which preferentially express HTLV-1 Tax persisted in vivo but failed to induce any diseases in immunocompetent syngeneic rats and that (ii) suboptimal levels of HTLV-1 for antibody responses allowed the establishment of persistent HTLV-1 infection.

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Human T-cell leukemia virus type 1 (HTLV-1) has been shown to be the etiologic agent of adult T-cell leukemia (ATL), but the in vivo mechanism by which the virus causes the malignant transformation is largely unknown. In order to investigate the mechanisms of HTLV-1 leukemogenesis, we developed a rat model system in which ATL-like disease was reproducibly observed, following inoculation of various rat HTLV-1-immortalized cell lines. When previously established cell lines, F344-S1 and TARS-1, but not TART-1 or W7TM-1, were inoculated, systemic multiple tumor development was observed in adult nude (nu/nu) rats. FPM1 cells, newly established from a heterozygous (nu/+) rat syngeneic to nu/nu rats, caused transient tumors only at the injection site in adult nu/nu rats, but could progressively grow in newborn nu/nu rats and metastasize in lymph nodes. The derivative cell line (FPM1- V1AX) serially passed through newborn nu/nu rats acquired the potency to grow in adult nu/nu rats. These results indicated that only some with additional changes but not all of the in vitro HTLV-1-immortalized cell lines possessed in vivo tumorigenicity. Using the syngeneic system, we further showed the inhibition of tumor development by transferring splenic T cells from immunized rats. Suggesting the involvement of T cells in the regression of tumors. This novel and reproducible nude rat model of human ATL would be useful for investigation of leukemogenesis and antitumor immune responses in HTLV-1 infection.

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

The major route of human T-cell leukemia virus type 1 (HTLV-1) infection is mother-to-child transmission caused by breast-feeding. We investigated the host immune responses to orally established persistent HTLV-1 infection in adult rats. HTLV-1-producing MT-2 cells were inoculated into immunocompetent adult rats either orally, intravenously, or intraperitoneally. HTLV-1 proviruses were detected in the peripheral blood and several organs for at least 12 weeks. Transmission of HTLV-1 to these animals was confirmed by analysis of HTLV-1 flanking regions. Despite persistent HTLV-1 presence, none of the orally inoculated rats produced detectable levels of anti-HTLV-1 antibodies, whereas all intravenously or intraperitoneally inoculated rats showed significant anti-HTLV-1 antibody responses. T-cell proliferative responses against HTLV-1 were also absent in orally inoculated rats. Our findings suggest that gastrointestinal exposure of adult rats to HTLV-1- infected cells induces persistent HTLV-1 infection in the absence of both humoral and cellular immune responses against HTLV-1. This immune unresponsiveness at primary infection may subsequently affect the host defense ability against HTLV-1.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ACADEMIC PRESS INC  

Stromal cell-derived factor 1 (SDF-1) inhibits T-cell tropic (T-tropic) HIV-1 infection in vitro. In this study, we examined the regulatory role of SDF-1 on HIV-1 replication in peripheral blood mononuclear cells (PBMC) of HIV-infected individuals. We found that the amount of SDF-1 mRNA in freshly isolated PBMC of HIV-1 carriers was higher than in healthy donors. Moreover, PBMC from some asymptomatic carriers (ACs) exhibited high levels of SDF-1 mRNA expression. The level of SDF-1 expression in PBMC did not correlate with the magnitude of CD8(+) T cell-mediated suppression of HIV-1 among ACs. SDF-1 inhibited HIV-1 replication at the viral entry step, whereas a single-cycle HIV-I infection system showed that the major part of the CD8(+) T-cell-mediated suppression occurs after intracellular penetration of the virus. Our results suggest that SDF-1 acts as a suppressor of virus replication in a CD8(+) T-cell-independent mechanism in HIV-infected individuals. (C) 1998 Academic Press.

DOI： 10.1006/viro.1998.9151

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Academic Press Inc.  

We investigated the mechanism of lymphocyte infiltration into tissues infected with human T-cell leukemia virus type 1 (HTLV-1). The cytokine SDF- 1/PBSF is a highly efficient chemoattractant for lymphocytes. Reverse transcription-PCR analysis showed that among various human T-cell lines, those infected with HTLV-1 selectively expressed the SDF-1 gene. Expression of the viral protein Tax in a human T-cell line induced the expression of the SDF-1 gene, indicating that the constitutive expression of SDF-1 in virus- infected cell lines is at least in part mediated by Tax. HTLV-1-infected T- cell lines also expressed CXCR-4, a receptor for SDF-1. Moreover, chemotaxis assay showed that a HTLV-1-infected cell line migrated toward synthetic SDF- 1. Thus, HTLV-1-infected cells are themselves responders for SDF-1. Our results suggest that SDF-1 induced by Tax may alter the distribution of HTLV- 1-infected cells in vivo
hence it may contribute to their infiltration into affected tissues in HTLV-1-associated inflammatory diseases.

DOI： 10.1006/viro.1997.8968

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER SOC MICROBIOLOGY  

CD8(+) T lymphocytes of asymptomatic human immunodeficiency virus type 1 (HIV-1) carriers (AC) suppress HIV-1 replication in vitro, Failure of host defense mechanisms and increased virus proliferation are associated with disease progression, The exact mechanisms inducing these changes at the advanced stage of the disease are still obscure. In this study, we searched for experimental conditions favoring the abrogation of the suppression of viral replication in peripheral blood mononuclear cells (PBMC) of AC by' using various pharmacological and biological probes modifying cell activation. Among such agents, staphylococcal enterotosin B (SEB) and phorbol 12-myristate 13-acetate (PMA) markedly increased otherwise low levels of HIV-1 replication in cultures of phytohemagglutinin-stimulated AC PBMC following in vitro HIV-1 LAI infection, A similar but less pronounced virus induction was also observed in macrophage-tropic HIV-1. Individual pretreatment of CD4(+) and CD8(+) PBMC fractions with these agents caused a reduction in CD8(+) cell proliferation and enhanced HIV-1 replication in CD4(+) cells, SEB- and PMA-mediated augmentation of HIV-1 replication in AC PBMC was significantly blocked by neutralizing antibody to tumor necrosis factor-alpha (TNF-alpha), although recombinant TNF-alpha alone failed to reproduce the effects of SEE or PMA. Our results suggest that the induction of TNF-alpha may be one of the mechanisms that overcomes the CD8(+)-induced suppression of HIV-1 replication in AC and that it may induce HIV-1 replication.

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Transgenic mice carrying tHe env-pX region of human T lymphocyte virus type I (HTLV-I) develop autoimmune arthropathy in high incidence. Adopting the approach that Fas-mediated apoptosis has a critical function in the elimination of self-reactive T cells, we examined the involvement of this apoptosis in the induction of autoimmunity in HTLV-I transgenic mice. Splenic T cells derived from the transgenic mice were more resistant to apoptosis induced by anti-Fas mAb than those of the nontransgenic mice, whereas no appreciable difference in apoptosis was detected for thymocytes from either mouse's type. The resistance of transgenic T cells may be due to Tax coded in the pX region, since Tax mediates the inhibition of anti-Fas-induced apoptosis in mature T cell line, Jurkat. Among the transgenic mice, the extent of the resistance to Fas-mediated apoptosis was further enhanced in transgenic T cells with disease. These results suggest that the escape of self-reactive T cells from Fas-mediated apoptosis in the periphery, is critical for the development of autoimmune arthropathy in HTLV-I transgenic mice.

DOI： 10.1084/jem.186.1.57

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Nature Publishing Group  

v-Rel is a transforming protein of the reticuloendotheliosis virus, and is a transcription factor regulating various cellular genes. We found that v-Rel activates the promoter of the proto-oncogene c-jun in a transient transfection assay system. Moreover, the expression of endogenous c-jun was augmented in cells expressing exogenous v-Rel, but not c-Rel. The transcriptional activities of v-Rel to the tested promoters containing the kB-site are lower than that of c-Rel, but that to the c-jun promoter was much higher than that of c-Rel. The N-terminal DNA binding domain of v-Rel, which is responsible for its high transforming activity of v-Rel was also responsible for the high transcriptional activity to the c-jun promoter. Thus, the activity of v-Rel upon the c-jun promoter correlates well with its transforming ability. Since c-Jun plays pivotal roles on cell proliferation in various types of cells, the activation of c-jun expression by v-Rel may be an essential step for the oncogenic transformation caused by v-Rel.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Nature Publishing Group  

Replication of human immunodeficiency virus type 1 (HIV-1) is suppressed in asymptomatic HIV-1 carriers (ACs). By using an in vitro experimental system, the mechanism of this suppression was investigated. Following in vitro infection of a laboratory HIV-1 strain, the peripheral blood mononuclear cells (PBMC) of ACs transiently supported a low level of viral replication, then the virus production rapidly decreased. PCR analysis revealed that HIV-1 proviral DNA integrated in the PBMC of ACs following infection gradually decreased. Such tapering consequences of in vitro HIV-1 infection in the PBMC of ACs were abrogated by depletion of CD8+ T cells from the culture. Furthermore, the viruses subsequently produced by the PBMC of an AC were less able to replicate than the virus produced by CD8+ cell-depleted PBMC of the same donor. These observations suggested that the CD8+ T cell-mediated suppression of HIV-1 replication in ACs may involve both cytocidal and cytostatic mechanisms: the former kills the cells producing viruses, and the latter inhibits viral spread by reducing viral infectivity.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Nature Publishing Group  

Replication of human immunodeficiency virus type 1 (HIV-1) is suppressed in asymptomatic HIV-1 carriers (ACs). By using an in vitro experimental system, the mechanism of this suppression was investigated. Following in vitro infection of a laboratory HIV-1 strain, the peripheral blood mononuclear cells (PBMC) of ACs transiently supported a low level of viral replication, then the virus production rapidly decreased. PCR analysis revealed that HIV-1 proviral DNA integrated in the PBMC of ACs following infection gradually decreased. Such tapering consequences of in vitro HIV-1 infection in the PBMC of ACs were abrogated by depletion of CD8+ T cells from the culture. Furthermore, the viruses subsequently produced by the PBMC of an AC were less able to replicate than the virus produced by CD8+ cell-depleted PBMC of the same donor. These observations suggested that the CD8+ T cell-mediated suppression of HIV-1 replication in ACs may involve both cytocidal and cytostatic mechanisms: the former kills the cells producing viruses, and the latter inhibits viral spread by reducing viral infectivity.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：STOCKTON PRESS  

The transcription factor v-Rel is a transforming protein of the reticuloendotheliosis virus. We found that v-Rel activates the promoter of the proto-oncogene c-jun, Two elements in the c-jun promoter were required for the activation by v-Rel, One was a kB-site (v-Rel binding site), and the other was a c-jun promoter region between -52 and +148 (c-jun promoter (-52/+148)). Two promoters with the kB-site(s), those of human immunodeficiency virus (HIV) and SV40, were not activated by v-Rel, but their kB-sites were activated when introduced upstream of the c-jun promoter (-52/+148), Thus, the c-jun promoter (-52/+148) had information for the selective activation of the c-jun promoter by v-Rel, v-Rel bound to the c-jun kB-site with the higher affinity than c-Rel, thereby activating the c-jun promoter more efficiently than c-Rel, Moreover, the activity of v-Rel mutants upon the c-jun promoter correlates with their transforming activity, Thus, the c-jun promoter activation by v-Rel may play a role in the transformation caused by v-Rel.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：KARGER  

Transcription of human T-cell leukemia virus type I is regulated by a viral transactivatior Tax, through the 21-bp sequence in the long terminal repeat (LTR). We found that cellular transcription factor AP-1 (c-Jun/c-Fos hetero-complex) bound to the 21-bp sequence. The binding affinity of the complex increased in proportion to the number of the 21-bp sequence, and the transcriptional activation by AP-1 became evident only when the reporters had more than three 21-bp sequences. Thus, AP-1 may play a role in the viral transcription from the LTR with three 21-bp sequences in the absence of Tax, such as in the early stage of the virus infection.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER SOC MICROBIOLOGY  

We have shown that Tax1 of human T-cell leukemia virus type 1 stimulates the expression of several cellular immediate-early genes (M. Fujii, T. Niki, T. Mori, T. Matsuda, M. Matsui, N. Nomura, and M. Seiki, Oncogene 6:1023-1029, 1991). In this study, the 5'-flanking region of the human fra-1 gene, which is a Tax1-inducible fos-related gene, was isolated and Tax1 or serum-responsive cis elements were analyzed to obtain further insight into the mechanism of Tax1 action. The 62-bp sequence starting 46 nucleotides upstream from the translation initiation site showed 71% homology with the sequence surrounding the TATA box of the c-fos promoter. Regulatory motifs identified in the c-fos promoter, such as an Ets-binding site, E boxes, a CArG box, c-fos AP-1 sites, and two retinoblastoma control elements, were also found upstream of the c-fos homology region. A 502-bp fragment containing these motifs mediated transcriptional activation by Tax1 or by serum in a transient transfection assay. Three independent Tax1-responsive regions (TRRs) were identified, and mutations in each revealed that one of the retinoblastoma control elements in TRR1 and the c-fos AP-1 sites in TRR2 and TRR3 were essential for the activation. Although TRR2 contains a CArG box-like sequence, it was a weak binding site for p67SRF, if it bound at all, and was not required for activation. All three TRRs could also mediate the signals stimulated by serum. Thus, Tax1 appears to activate fra-1 gene expression by means of a part of the cellular machinery similar to that which mediates growth signals.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：COLD SPRING HARBOR LAB PRESS  

Tax1 of human T-cell leukemia virus type 1 (HTLV-1) is a transcriptional activator for viral gene expression and is also a transforming protein through inducing the expression of several cellular genes under the control of mitogenic signals. We identified the CArG boxes as a Tax1-responsive cis-acting element for the cellular immediate early genes c-fos, egr-1, and egr-2. Using a chimeric protein consisting of the CArG-binding factor p67SRF and the heterologous DNA-binding domain of a yeast transcription factor GAL4, we demonstrated that Tax1 activates the transcriptional activity of p67SRF through the GAL4-binding site. The carboxy-terminal half of p67SRF, which lacks domains for DNA-binding, dimerization, and ternary complex formation with p62TCF, was sufficient for the activation by Tax1. Tax1 produced in Escherichia coli bound p67SRF in vitro. The complex formation in vivo was also indicated by the finding that the acidic activation domain of VP16, by fusion to p67SRF, can complement the transcriptional activation function of a mutant Tax1 in trans. Thus, Tax1 activates CArG-mediated transcription without mitogenic signals through interaction with a CArG-binding factor, p67SRF. This must be one of the primary steps by which Tax1 causes aberration in growth control of the infected cells.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：WILEY-LISS  

DOI： 10.1002/jcp.1041360215

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：CENTER ACADEMIC PUBL JAPAN  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Kluwer Academic Publishers  

The expression of transcripts of the c-myb and c-myc protooncogenes and the interleukin 2 receptor (IL-2R) gene in human T cells infected with human T-cell leukemia virus type 1 (HTLV-1) after exposure to interleukin 2 (IL-2) were examined. Infection with HTLV-1 is known to be associated with constitutive expression of IL-2R, although infected cells do not require IL-2 for growth. Northern blot analysis showed that expression of the mRNAs of the c-myb, c-myc, and IL-2R genes were markedly increased by addition of IL-2 into the cultures, indicating that IL-2R transduced signals for gene expression in these cells as in normal T cells. Studies on distinct HTLV-1-infected T cell clones that differed in numbers of high-affinity IL-2R, showed that the extents of increase in mRNA expression by IL-2 were correlated with the number of high-affinity IL-2R. This correlation was confirmed by demonstration that the levels of mRNA expression were proportional to the numbers of IL-2-bound high-affinity but not low-affinity receptors. Thus, the signals induced by IL-2 for gene expression may be through high-affinity IL-2R. © 1987 Martinus Nijhoff Publishing.

DOI： 10.1007/BF00125684

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記述言語：英語   出版者・発行元：VCH PUBLISHERS INC  

DOI： 10.1002/eji.1830170925

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER ASSOC IMMUNOLOGISTS  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ROCKEFELLER UNIV PRESS  

DOI： 10.1084/jem.163.3.550

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記述言語：英語   出版者・発行元：ROCKEFELLER UNIV PRESS  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：NATL ACAD SCIENCES  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：WILEY-LISS  

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記述言語：日本語

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記述言語：英語   出版者・発行元：BIOMED CENTRAL LTD  

DOI： 10.1186/1742-4690-10-38

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記述言語：英語   出版者・発行元：BIOMED CENTRAL LTD  

DOI： 10.1186/1742-4690-10-28

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記述言語：英語   出版者・発行元：日本癌学会  

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記述言語：日本語  

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記述言語：日本語   出版者・発行元：診断と治療社  

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その他リンク： http://search.jamas.or.jp/link/ui/2011301891

記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）   出版者・発行元：MARY ANN LIEBERT INC  

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記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）   出版者・発行元：MARY ANN LIEBERT INC  

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記述言語：日本語  

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記述言語：英語   出版者・発行元：(一社)日本血液学会-東京事務局  

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記述言語：英語   出版者・発行元：日本癌学会  

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記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）   出版者・発行元：MARY ANN LIEBERT INC  

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記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）   出版者・発行元：MARY ANN LIEBERT INC  

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記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）   出版者・発行元：MARY ANN LIEBERT INC  

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記述言語：英語  

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記述言語：日本語   出版者・発行元：医薬ジャーナル社  

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その他リンク： http://search.jamas.or.jp/link/ui/2007341585

記述言語：英語   出版者・発行元：BIOMED CENTRAL LTD  

The 12(th) International Conference on Human Retrovirology: HTLV and Related Retroviruses, was held at the Half Moon Hotel in Montego Bay, Jamaica, from June 22(nd) to June 25(th) 2005. The scientific conference, sponsored by the International Retrovirology Association, is held biennially at rotating international venues around the world. The meeting brings together basic scientists, epidemiologists and clinical researchers to discuss findings to prevent HTLV infection or develop new therapies against HTLV-mediated diseases. The Association fosters the education and training of young scientists to bring new approaches to the complex problems of HTLV research, such as translational research to bring findings from the laboratory into clinical trials that benefit HTLV-infected patients. The breadth and quality of research presentations and workshops at the 12th International Conference indicate that these goals are being accomplished. As HTLV research enters its third decade a new generation of scientists face many challenges. However, HTLV scientists and clinicians displayed exciting new approaches and discoveries during plenary talks and poster sessions. The conference encouraged research in HTLV infections and disease, fostered collaborations, and stimulated new partnerships between clinicians and scientists to encourage clinical trials and novel therapeutic interventions.

DOI： 10.1186/1742-4690-2-61

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記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）   出版者・発行元：MARY ANN LIEBERT INC  

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記述言語：英語  

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記述言語：日本語  

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記述言語：日本語   出版者・発行元：日本ウイルス学会  

DOI： 10.2222/jsv.52.103

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その他リンク： https://jlc.jst.go.jp/DN/JALC/00154219891?from=CiNii

記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）   出版者・発行元：STOCKTON PRESS  

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記述言語：英語   出版者・発行元：STOCKTON PRESS  

Tax of human T-cell leukemia virus type I (HTLV-I) activates transcription at a CArG box of various immediate early genes such as the proto-oncogene c-fos. To do this, Tax does not directly bind to the CArG box, but instead binds to the CArG binding factor SRF. In this study, we investigated the domain of SRF required for the activation by Tax and studied the role of this domain on transcriptional regulation at the CArG box. Using a fusion protein of SRF with a yeast transcription factor GAL4, the 14 amino acid (aa) portion (aa 422-435) of SRF was identified as the domain required for Tax activation [Tax-responsive region of SRF (TRRS)]. By means of a two hybrid system, we showed that TRRS was essential for the interaction of SRF with Tax in vivo. The over-expression of SRF with a deletion of TRRS inhibited the Tax activation at the CArG box. Thus, TRRS is the domain of SRF that is essential for Tax activation at the CArG box. Unlike to Tax activation, TRRS was not required for TPA (12-o-tetradecanoylphobol-13-acetate) induction at the CArG box, but a TRRS deletion enhanced the basal activity at the CArG box both under serum-starved and TPA-stimulated conditions. These results suggest that TRRS negatively regulates the transcriptional activation function of SRF, and consequently contributes to the low basal activity at the CArG box before TPA induction.

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記述言語：英語   出版者・発行元：AMER SOC MICROBIOLOGY  

We previously reported that Tax1 of human T-cell leukemia virus type I interacts directly with serum response factor (SRF) and that Tax1 activates the transcription of several cellular immediate-early genes through the SRF binding site (CArG box). This activation required the transcriptional activation function of Tax1, identified as an activity of GALTax (a chimeric Tax1 with the yeast transcription factor GAL4) at the GAL4-binding site. In this study, we examined whether SRF plays a role in the transcriptional activation function of Tax1. Expression of Tax1 suppressed the GALTax activity at the GAL4 site as a result of squelching, and the suppressed activity was recovered by the overexpression of SRF, suggesting that SRF is a factor that is required for GALTax activity and that is inhibited by competition with Tax1. The expression of antisense SRF RNA specifically inhibited GALTax activity to less than 20%. Deletion of the Tax1 interaction domain of SRF at its C terminus converted SRF from an activator of GALTax to an inhibitor. These results suggest that SRF is an essential component of the transcriptional activation of Tax1 in addition to a mediator of CArG box binding.

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記述言語：英語   出版者・発行元：AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC  

A growth factor-like activity for erythroid cells (erythroid-potentiating activity) is produced by the T cells infected with human T cell leukemia virus type 2 (HTLV-2) (Gasson, J. C., Golde, D, W, Kaufman, S. E., Westbrook, C. A, Hewick, R. M., Kaufmann, R. J., Wong, G. G., Temple, P.A., Leary, A. C., Brown, E. L., Orr, E. C., and Clark, S. C. (1985) Nature 315, 768-771) and is reportedly identical with tissue inhibitors of matrix metalloproteinases-l (TIMP-1) (Docherty, A. J. P., Lyons, A., Smith, B. J., Wright, E. M., Stephens, P. E., Harris, T J. R., Murphy, G., and Reynolds, J. J. (1985) Nature 318, 66-69). We found that adult T-cell leukemia cell lines infected with HTLV-1 also express high levels of a TMIP-1 transcript. A viral transactivator of HTLV-1, Taxi, in a human T-cell line (Jurkat), was sufficient to stimulate transcription of the TIMP-1 gene. Deletion and mutation analysis of the TIMP-1 gene promoter showed that the AP-1 binding site in the 38-base pair sequence conserved between the human and mouse genes was essential for activation by Taxi. The transactivator of HTLV-2 also stimulated the promoter through the same cis-element. The reported growth promoting activity of TIMP-1 against erythroid cells and potentially against HTLV-1-infected T-cells may modulate the clinical course of adult T-cell leukemia.

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記述言語：英語   掲載種別：記事・総説・解説・論説等（学術雑誌）   出版者・発行元：STOCKTON PRESS  

Taxi of human T-cell leukemia virus type 1 (HTLV-1) is an enigmatic viral transactivator that regulates expression of the viral gene and also several cellular genes normally controlled by various mitogenic signals. However, previous studies have failed to define the functional domains of Taxi for enhancer specificities and for transcriptional activation (95% of the protein portion was indispensable for the activation function). This complexity has hampered understanding of the molecular basis of Taxi action. In this study, we analysed the activation function of a Taxi fused to the heterologous DNA-binding domain of the yeast transcription factor GAL4 and dissected the domain required for the activation function by using derivatives of a Taxi mutant with an insertion between amino acids (a.a.) 170 and 171. Analysis of the derivatives of the mutant fusion protein having various partial overlaps encompassing the interrupted site suggested that two contiguous stretches, AD-I (2-255 a.a.) and AD-II (227-337 a.a.), should be both intact for the activation function of Taxi and that they form a functional activation domain.

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記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）   出版者・発行元：WILEY-LISS  

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記述言語：英語   掲載種別：記事・総説・解説・論説等（学術雑誌）   出版者・発行元：STOCKTON PRESS  

Tax1 of human T-cell leukemia virus type 1 (HTLV-1) activates viral transcription dependent upon three 21-bp enhancer elements in the long terminal repeat. Difficulties in detecting any association of Tax1 with the viral enhancer have hampered elucidation of the molecular mechanisms of Tax1-mediated transcriptional activation. By constructing a fusion protein with the heterologous DNA-binding domain of yeast GAL4, Tax1 was shown to be a potent transcriptional activator dependent on the presence of GAL4-binding sites. Deletions of the Tax1 portion of the fusion protein revealed that almost the entire region of Tax1 (amino acids 2-337) is required for activation, and the activity correlated well with that of the viral enhancer. The GAL/Tax1 mutant lacking 41 residues of the C-terminus of Tax1. GAL/Tax1(2-312). was inactive for the viral enhancer, but activity was recovered by adding the heterologous activation domain of herpes simplex virus VP16. These results indicate that Tax1 has two distinct but overlapping functional domains for transcriptional activation and for enhancer specificity. Thus, Tax1 is thought to be a transcription factor acting in the enhancer complex rather than as a catalytic or allosteric modifier of pre-existing cellular transcription factors.

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記述言語：英語   出版者・発行元：STOCKTON PRESS  

Human T-cell leukemia virus type 1 (HTLV-1) is an etiological agent of adult T-cell leukemia (ATL). We showed here by mobility-shift assay that T-cell lines transformed with the virus contained high levels of AP-1 activities. Consistent with this result, these cell lines expressed increased levels of mRNAs encoding the AP-1 proteins, c-Fos, Fra-1, c-Jun, JunB, and JunD. Previously, transcription of the c-fos gene has been reported to be transactivated by the viral transcription factor, Tax1. By using the human T-cell line (JPX-9), in which expression of the Tax1 is inducible, we showed that expression of mRNAs for Fra-1, c-Jun, and JunD was also transactivated by Tax1. Moreover, Tax1 activated expression of two other transcription factors having zinc finger motifs, Egr-1 and Egr-2, in the same cells. The Tax1-inducible transcription factors identified here are encoded by the members of immediate early genes under the control of growth signals. Thus, Tax1 was suggested to replace growth signals, at least in part, by this mechanism.

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DOI： 10.1016/0014-5793(87)80308-3

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記述言語：英語   出版者・発行元：JAPAN CANCER ASSN CANCER INST  

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記述言語：英語   出版者・発行元：AMER ASSOC IMMUNOLOGISTS  

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記述言語：英語   掲載種別：記事・総説・解説・論説等（学術雑誌）   出版者・発行元：AMER ASSOC IMMUNOLOGISTS  

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