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ABSTRACT: 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.
Genes to Cells 12/2012; · 2.68 Impact Factor
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ABSTRACT: 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 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 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.
Cancer Science 12/2012; · 3.33 Impact Factor
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ABSTRACT: 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 to inhibit ROS-dependent apoptosis. This antioxidant activity of SGs is controlled by two SG components, G3BP1 and 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 the cell fate under stress conditions.
Molecular and cellular biology 12/2012; · 6.06 Impact Factor
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ABSTRACT: 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.
Virus Genes 09/2012; · 1.85 Impact Factor
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ABSTRACT: 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 Science 02/2012; 103(2):369-74. · 3.33 Impact Factor
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ABSTRACT: 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.
Virus Genes 04/2010; 40(2):193-9. · 1.85 Impact Factor
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Shigeki Sawada,
Chie Ishikawa,
Hiroe Tanji,
Sawako Nakachi,
Masachika Senba,
Taeko Okudaira,
Jun-Nosuke Uchihara,
Naoya Taira,
Kazuiku Ohshiro,
Yasuaki Yamada,
Yuetsu Tanaka,
Hiroshi Uezato,
Koichi Ohshima,
Ken Sasai,
Boudewijn M T Burgering,
Madeleine Duc Dodon, Masahiro Fujii,
Hajime Sunakawa,
Naoki Mori
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ABSTRACT: Caveolin-1 is implicated in the regulation of signal pathways. Adult T-cell leukemia (ATL) is a T-cell malignancy causatively associated with human T-cell leukemia virus type 1 (HTLV-1). To determine the role of caveolin-1 in leukemogenesis, we examined caveolin-1 expression levels in HTLV-1-infected T-cell lines and ATL cells. These cells expressed high levels of caveolin-1 compared with uninfected T-cell lines and normal peripheral blood mononuclear cells (PBMCs). Caveolin-1-positive ATL cells were detected in ATL lymph nodes and skin lesions, and caveolin-1 was also detected in the plasma of patients with ATL. Infection of a human T-cell line, an epithelial cell line, and normal PBMCs with HTLV-1 induced caveolin-1 expression. The viral protein Tax transcriptionally activated caveolin-1 gene through nuclear factor-kappaB and cAMP response element binding protein signal pathways. HTLV-1-infected T-cell lines, and ATL cells are known to be resistant to transforming growth factor beta (TGF-beta)-induced growth inhibition. Caveolin-1 was colocalized with TGF-beta type I receptor in HTLV-1-infected T-cell lines and suppressed TGF-beta signaling. Caveolin-1 knockdown in an HTLV-1-infected T-cell line exhibited susceptibility to TGF-beta. Thus, we describe a new function for Tax, repression of TGF-beta signaling through caveolin-1 expression, which may play a critical role in ATL leukemogenesis.
Blood 03/2010; 115(11):2220-30. · 9.90 Impact Factor
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ABSTRACT: 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.
Retrovirology 12/2009; 6:117. · 6.47 Impact Factor
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ABSTRACT: 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-kappa B2 (NF-kappa B2)/p100.
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.
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.
Retrovirology 09/2009; 6:83. · 6.47 Impact Factor
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ABSTRACT: 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-kappaB, 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.
Journal of Biological Chemistry 08/2009; 284(38):25501-11. · 4.77 Impact Factor
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ABSTRACT: 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-kappaB 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-kappaB-driven transcription mediated by p65 (the classical pathway) without inhibiting the alternative NF-kappaB 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-kappaB target genes, such as IL-8, IL2RA, IRF4, VCAM-1, and VEGF. Selective suppression of the classical NF-kappaB pathway by HBZ renders the alternative NF-kappaB pathway predominant after activation of NF-kappaB by Tax or other stimuli, which might be critical for oncogenesis.
Blood 01/2009; 113(12):2755-64. · 9.90 Impact Factor
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ABSTRACT: 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 Tax1C lacking PBM, whereas transiently expressed Scribble was localized in the cytoplasm and colocalized with Tax1C 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.
Virus Genes 10/2008; 37(2):231-40. · 1.85 Impact Factor
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ABSTRACT: 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 (GLUT1DeltaC). GLUT1 expression in MDBK cells induced HTLV-1-mediated syncytium formation, and the activity was much greater than that of GLUT1DeltaC. 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.
Virus Genes 09/2008; 37(1):9-15. · 1.85 Impact Factor
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ABSTRACT: 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-kappaB 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-kappaB 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-kappaB in ATL, and thereby playing a role in the ATL pathogenesis.
Cancer Science 05/2008; 99(4):792-8. · 3.33 Impact Factor
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ABSTRACT: 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-κB to be a causative factor mediating the abnormal proliferation of leukemic cells, thus resulting in the development of ATL. A rearranged NF-κB2/p100 gene was isolated from an ATL-derived cell line, which was generated by a chromosomal translocation. The isolated NF-κB2 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-κB2 gene product (p58) was localized in the nucleus, and formed a complex with NF-κB p65 or RelB. Moreover, a T-cell line expressing p58 increased the amount of an NF-κB2-inducible gene, NF-κB2/p100 by itself. These results suggest that such NF-κB2 gene rearrangement may therefore be a factor in the constitutive activation of NF-κB in ATL, and thereby playing a role in the ATL pathogenesis. (Cancer Sci 2008; 99: 792–798)
Cancer Science 03/2008; 99(4):792 - 798. · 3.33 Impact Factor
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Eiichi Kodama,
Masaya Orita,
Naoyuki Masuda,
Osamu Yamomoto, Masahiro Fujii,
Tetsuro Ohgami,
Shunji Kageyama,
Mitsuaki Ohta,
Toshifumi Hatta,
Hiroshi Inoue,
Hiroshi Suzuki,
Kenji Sudo,
Yasuaki Shimizu,
Masao Matsuoka
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ABSTRACT: YM-215389 and YM-228855 are thiazolidenebenzenesulfonamide (TBS) derivatives and novel non-nucleoside reverse transcriptase inhibitors (NNRTIs) that inhibit not only wild-type, but also the K103N- and Y181C-substituted reverse transcriptase (RT) of HIV type-1 (HIV-1).
To characterize the binding modes of the TBS derivatives in detail, the anti-HIV-1 activities of YM-215389 and YM-228855 against various NNRTI-resistant clones were examined. Docking studies with HIV-1 RT were also performed.
YM-215389, which effectively inhibits various NNRTI-resistant clones, interacted with L100, K103, V106 and Y318 through the benzene ring and with E138, V179, Y181, Y188 and W229 through the thiazole ring. A single amino acid substitution confers only moderate resistance to YM-215389; indeed, four amino acid substitutions (V106L, V108I, E138K and L214F) were necessary for high-level resistance. Although the activity of YM-228855, a derivative of YM-215389 that has two bulky and rigid cyano-moieties on the benzene ring, was 10x more potent against HIV-1 than YM-215389, its anti-HIV-1 activity was readily reduced with single substitutions as with Y181I and K103N.
These results provide structural information for optimizing the TBS derivatives in an attempt to construct ideal NNRTIs that maintain anti-HIV-1 activity to various HIV-1 variants.
Antiviral chemistry & chemotherapy 02/2008; 19(3):133-41.
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ABSTRACT: 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-kappaB2/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-kappaB2/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-kappaB2/p100 plays a crucial role in the Tax1-mediated transformation of T cells and that NF-kappaB2/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.
Journal of Virology 12/2007; 81(21):11900-7. · 5.40 Impact Factor
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ABSTRACT: Using 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 NII561-2000-related viruses were infectious gastroenteritis, rash, upper respiratory tract infection, and paralysis, in addition to Reye syndrome in the 1-year-old girl.
Emerging infectious diseases 07/2007; 13(6):889-95. · 6.17 Impact Factor
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ABSTRACT: 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 interacting 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.
Virus Genes 05/2007; 34(2):127-36. · 1.85 Impact Factor
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Tatsuaki Morokata,
Keiko Suzuki,
Yohei Masunaga,
Katsunari Taguchi,
Koichiro Morihira,
Ippei Sato, Masahiro Fujii,
Satoko Takizawa,
Yuichi Torii,
Naoyoshi Yamamoto,
Masayuki Kaneko,
Toshimitsu Yamada,
Koichiro Takahashi,
Yasuaki Shimizu
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ABSTRACT: CC chemokine ligand 11 (CCL11/eotaxin) and other CC chemokine receptor 3 (CCR3) ligands (CCL24/eotaxin-2, CCL26/eotaxin-3, CCL13/monocyte chemotactic protein-4, etc.) play important roles in the chemotaxis and activation of eosinophils and other CCR3-expressing cells (basophils, mast cells, and CD4(+) T helper 2 cells) in allergic inflammation incidents, including asthma and rhinitis. A newly synthesized compound, N-{(3R)-1-[(6-fluoro-2-naphthyl)methyl]pyrrolidin-3-yl}-2-{1-[(5-hydroxy-3-methylpyridin-2-yl)carbonyl]piperidin-4-ylidene}-acetamide hemifumarate (YM-355179), inhibited the binding of CCL11 and CCL5/regulated on activation normal T cell expressed and secreted to CCR3-expressing B300-19 cells with IC(50) values of 7.6 and 24 nM, respectively. In contrast, YM-355179 did not affect the binding of CCL5 to CCR1 or CCR5. In functional assays, YM-355179 inhibited CCL11-induced, intracellular Ca(2+) influx, chemotaxis, and eosinophil degranulation with IC(50) values of 8.0, 24, and 29 nM, respectively. YM-355179 did not, however, affect any CC chemokine receptor (CCR1, CCR2, CCR4, or CCR5)-mediated Ca(2+) influx signals. Furthermore, oral administration of YM-355179 (1 mg/kg) inhibited CCL11-induced shape change of whole blood eosinophils in cynomolgus monkeys. Intravenous injection of YM-355179 (1 mg/kg) also inhibited eosinophil infiltration into airways of cynomolgus monkeys after segmental bronchoprovocation with CCL11. These results indicate that YM-355179 is a novel, selective, and orally available CCR3 antagonist with therapeutic potential for treating eosinophil-related allergic inflammatory diseases.
Journal of Pharmacology and Experimental Therapeutics 05/2006; 317(1):244-50. · 3.83 Impact Factor
