Are you Chiyoko Nukuzuma?

Claim your profile

Publications (8)16.04 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: JC polyomavirus (JCV) causes progressive multifocal leukoencephalopathy (PML), a fatal demyelinating disease of the central nervous system (CNS) in immunocompromised patients, and particularly in the severe immunosuppression associated with acquired immunodeficiency syndrome (AIDS). HIV-1 can lead to the production of tumor necrosis factor-alpha (TNF-α) in the CNS. Our aim was to examine the effects of TNF-α on JCV gene expression and replication using a human neuroblastoma cell line, IMR-32, transfected with JCV DNA, M1-IMRb. Quantitative RT-PCR analysis of JCV large T antigen and VP1 mRNA, the viral DNA replication assay, and the DNase protection assay were carried out. TNF-α treatment of IMR-32 cells transfected with JCV DNA induced large T antigen mRNA and JCV DNA replication, while other effects on VP1 mRNA expression and virus production were marginal. In addition, ELISA analysis of the nuclear p65 subunit of nuclear factor κB (NF-κB), which is a hallmark of NF-κB pathway activation, of IMR-32 cells upon TNF-α treatment showed that TNF-α treatment activated the NF-κB pathway in IMR-32 cells. Taken together, our results suggest that TNF-α stimulation could induce JCV replication associated with the induction of JCV large T antigen mRNA through the NF-κB pathway in IMR-32 cells transfected with JCV DNA. Our findings may contribute to further understanding of the pathogenesis of AIDS-related PML. J. Med. Virol. © 2014 Wiley Periodicals, Inc.
    Journal of Medical Virology 01/2014; · 2.37 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The incidence of progressive multifocal leukoencephalopathy (PML) has increased due to the AIDS pandemic, hematological malignancies, and immunosuppressive therapies. Recently, the number of cases of monoclonal antibody-associated PML has increased in patients treated with immunomodulatory drugs such as natalizumab. However, no common consensus regarding PML therapy has been reached in clinical studies. In order to examine the suppression of JC virus (JCV) replication by 3-aminobenzamide (3-AB), a representative PARP-1 inhibitor, a DNA replication assay was carried out using the neuroblastoma cell line IMR-32 and IMR-adapted JCV. The suppression of JCV propagation by 3-AB was also examined using JCI cells, which are a carrier culture producing continuously high JCV titers. The results indicated that PARP-1 inhibitors, such as 3-aminobenzamide (3-AB), suppress JCV replication and propagation significantly in vitro, as judged by DNA replication assay, hemagglutination, and real-time PCR analysis. It has been also shown that 3-AB reduced PARP-1 activity in IMR-32 cells. According to the results of the MTT assay, the enzyme activity of 3-AB-treated cells was slightly lower than that of DMSO-treated cells. However, the significant suppression of JCV propagation is not related to the slight decrease in cell growth. To our knowledge, this is the first report that PARP-1 inhibitor suppresses the replication of JCV significantly in neuroblastoma cell lines via the reduction of PARP-1 activity. Thus, PARP-1 inhibitors also may be a novel therapeutic drug for PML. J. Med. Virol. © 2012 Wiley Periodicals, Inc.
    Journal of Medical Virology 10/2012; · 2.37 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The high incidence of progressive multifocal leukoencephalopathy (PML) among individuals with acquired immunodeficiency syndrome (AIDS) is similar to the incidence of other immunocompromised diseases. The pathogenic JC virus (JCV) with rearranged regulatory regions (PML-type) causes PML, a demyelinating disease in the brains of immunocompromised patients. In a previous study, Tat protein, encoded by human immunodeficiency virus type 1 (HIV-1), markedly enhanced the expression of a reporter gene under control of the JCV late promoter. In order to examine the enhancement of JCV replication by Tat protein, the neuroblastoma cell line IMR-32 was used because it enables IMR-32-adapted JCV. The extent of JCV replication in IMR-32 cells treated with Tat protein was significantly higher than that in untreated IMR-32 cells. The enhancement of JCV propagation by Tat protein was also examined using IMR-32-derived JCV producing (JCI) cells which continuously produce JCV. Treatment of JCI cells with Tat protein led to a significant increase in the titers of progeny viruses. It has also been shown that Tat protein leads to a decrease in the expression of purine-rich element binding protein α (Purα) as an important mediator of JCV replication in IMR-32 cells. Thus, it is probable that Tat protein enhances JCV replication in IMR-32 cells via the down-regulation of Purα expression and cell proliferation. To our knowledge, this is the first report that exogenous Tat protein enhances the replication of JCV efficiently in neuroblastoma cell lines.
    Journal of Medical Virology 04/2012; 84(4):555-61. · 2.37 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The high incidence of progressive multifocal leukoencephalopathy (PML) in AIDS patients compared with many other immunosuppressive diseases suggests that HIV-1 infection is strictly related to the activation of JC virus (JCV) propagation. In this report, propagation of PML-type JCV in COS-7-derived cell lines stably expressing HIV-1 Tat (COS-tat cells) has been examined. In COS-tat cells, production of viral particles and replication of genomic DNA were markedly increased compared to COS-7 cells, as judged by HA and real-time PCR analyses. These results demonstrate that COS-tat cells provide a useful model system for studying HIV-1 Tat-mediated propagation of PML-type JCV.
    Microbiology and Immunology 12/2010; 54(12):758-62. · 1.55 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Pathogenic JCV with rearranged regulatory regions (PML-type) causes PML, a demyelinating disease, in the brains of immunocompromised patients. On the other hand, archetype JCV persistently infecting the kidney is thought to be converted to PML-type virus during JCV replication in the infected host under immunosuppressed conditions. In addition, Tat protein, encoded by HIV-1, markedly enhances the expression of a reporter gene under control of the JCV late promoter. In order to examine the influence of Tat on JCV propagation, we used kidney-derived COS-7 cells, which only permit archetype JCV, and established COS-tat cells, which express HIV-1 Tat stably. We found that the extent of archetype JCV propagation in COS-tat cells is significantly greater than in COS-7 cells. On the other hand, COS-7 cells express SV40 T antigen, which is a strong stimulator of archetype JCV replication. The expression of SV40 T antigen was enhanced by HIV-1 Tat slightly according to real-time RT-PCR, this was not closely related to JCV replication in COS-tat cells. The efficiency of JCV propagation depended on the extent of expression of functional Tat. To our knowledge, this is the first report of increased production of archetype JCV in a culture system using cell lines stably expressing HIV-1 Tat. We propose here that COS-tat cells are a useful tool for studying the role of Tat in archetype JCV replication in the development of PML.
    Microbiology and Immunology 11/2009; 53(11):621-8. · 1.55 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Human polyomavirus, JCV, causes fatal demyelinating disease, progressive multifocal leukoencephalopathy (PML). It has been shown that 5HT(2A)R acts as a cellular receptor for JCV on human glial cells. In the current study, we examined the inhibitory effects of 5HT(2A)R antagonists, ketanserin and ritanserin, both on JCV infection and on propagation by using human neuroblastoma cells IMR-32 and JCI, which continuously produce JCV. Transcriptional analysis revealed that 5HT(2A)R was constitutively expressed in JCI cells. Treatments with 5HT(2A)R antagonists led to a significant reduction in the titers of progeny viruses and the population of infected JCI cells. In addition, the amount of JCV genomic DNA was decreased in JCI cells in the presence of 5HT(2A)R antagonists. These results indicate that 5HT(2A)R antagonists have an inhibitory effect on JCV infection and reproduction, and JCI cells are applicable to an experimental model for pharmacological evaluation of antiviral agents against JCV.
    Microbiology and Immunology 10/2009; 53(9):496-501. · 1.55 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: At present it remains unknown if the JC virus (JCV), the causative agent of progressive multifocal leukoencephalopathy, employs specific cellular receptors or cell membrane factors for viral entry. To investigate this, we have examined the cell-specific replication of a chimeric JCV, which contains the control region (CR) cloned from JCI and the coding sequences of the prototype Mad-1 virus. We examined and compared the hemagglutination (HA) titers produced during viral multiplication following microinjection, transfection with chloramphenicol acetyl-transferase (CAT) assays, and inoculation using a permissive cell line IMR-32 and three non-permissive cell lines COS-7, CV-1, and A431. Virus microinjected into cells proliferated well in both IMR-32 and COS-7, but not in the non-permissive CV-1 and A431 cell lines. When cells were infected with the chimeric JCV, the HA titers were high in IMR-32, low in COS-7, and negative in the other cell lines. Chloramphenicol acetyltransferase assays demonstrated that the CR was active in IMR-32, COS-7, and CV-1, and inactive in A431 cells. The results suggest that not only nuclear, but also cell membrane factors play an important role in the susceptibility of cells to JCV infection.
    Neuropathology 05/2007; 18(1):67 - 72. · 1.91 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: This report concerns a carrier cell culture (designated JCI) infected persistently with JC virus (JCV). Immunostaining with an anti-JCV antiserum revealed that JCI was a carrier culture in which only a small fraction of the cells (approximately 1.5%) produced the virus. The JCV titre was increased strikingly by incubating confluent JCI cells for 4-6 days in medium containing a low concentration of fetal bovine serum (2%). Viral genomes cloned from the persistently infected JCI cells were heterogeneous with respect to size, but most clones had an alteration of the same regulatory region (designated CR-JCI). Transfection experiments with a chimeric JCV DNA (Mad-1/CR-JCI), in which the regulatory region was CR-JCI and the other region was derived from an infectious JCV (Mad-1) DNA, showed that CR-JCI was less efficient in inducing viral growth than the regulatory regions of IMR-32-adapted JCVs. The transfected cells could be readily subcultured, and they continued to produce JCV. It is concluded that a decrease in the activity of the JCV regulatory region is of importance for the maintenance of the carrier state of JCI cells.
    Journal of Medical Virology 01/1996; 47(4):370-7. · 2.37 Impact Factor