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Biomedical subjects

Naoko Kato

Publications and source records attributed to Naoko Kato.

At least 19 recordsLinked to original sources
PubMed2007

Serine/threonine kinase PKR: a sentinel kinase that discriminates a signaling pathway mediated by TLR4 from those mediated by TLR3 and TLR9.

Cells of the innate immune system discriminate between "noninfectious self" and "infectious nonself" via pattern recognition receptors known as Toll-like receptors (TLRs). Though TLRs and the related interleukin 1 receptors share considerable homology in their cytoplasmic domains and adaptor molecules, signaling cascades may substantially differ from one another depending on the adaptor proteins recruited. Here we show that ectopic overexpression of catalytically inactive dominant-negative PKR expression system suppressed NF- kappa B activation mediated by TLR3, TLR9, TNF receptor 1 and 2 (TNF-R 1/2), but not by TLR4. Physiological relevance of the observations described here are discussed.

Animals↗
PubMed2006

Intrinsic kinase activity and SQ/TQ domain of Chk2 kinase as well as N-terminal domain of Wip1 phosphatase are required for regulation of Chk2 by Wip1.

The anti-oncogenic Chk2 kinase plays a crucial role in DNA damage-induced cell cycle checkpoint regulation. Recently, we have shown that Chk2 associates with the oncogenic Wip1 (PPM1D) phosphatase and that Wip1 acts as a negative regulator of Chk2 during DNA damage response by dephosphorylating phosphorylated Thr-68 in activated Chk2 (Fujimoto, H., Onishi, N., Kato, N., Takekawa, M., Xu, X. Z., Kosugi, A., Kondo, T., Imamura, M., Oishi, I., Yoda, A., and Minami, Y. (2006) Cell Death Differ. 13, 1170-1180). Here, we performed structure-function analyses of Chk2 and Wip1 by using a series of deletion or amino acid-substituted mutant proteins of Chk2 and Wip1. We show that nuclear localization of both Chk2 and Wip1 is required for their association in cultured cells and that the serine-glutamine (SQ)/threonine-glutamine (TQ) domain of Chk2, containing Thr-68, and the N-terminal domain of Wip1, comprising about 100 amino acids, are necessary and sufficient for the association of both molecules. However, it was found that an intrinsic kinase activity of Chk2, but not phosphatase activity of Wip1, is required for the association of fulllength Chk2 and Wip1. Interestingly, we also show that the mutant Wip1 proteins, bearing the N-terminal domain of Wip1 alone or lacking an intrinsic phosphatase activity, exhibit dominant negative effects on the functions of the wild-type Wip1, i.e. ectopic expression of either of these Wip1 mutants inhibits dephosphorylation of Thr-68 in Chk2 by Wip1 and anti-apoptotic function of Wip1. These results provide a molecular basis for developing novel anti-cancer drugs, targeting oncogenic Wip1 phosphatase.

Animals↗
PubMed2006

Effect of macrophage migration inhibitory factor (MIF) on acute graft-versus-host disease in a murine model of allogeneic stem cell transplantation.

Macrophage migration inhibitory factor (MIF) may play an important role in the pathogenesis of acute graft-versus-host disease (aGVHD) after allogeneic hematopoietic stem cell transplantation (HSCT). We examined whether MIF has an influence on the development of aGVHD and survival using BALB/c-based MIF knock-out (MIF KO) mice. Although MIF expression was observed in lymphocytes that had infiltrated the liver during aGVHD in both wild-type (WT) and MIF KO mice that received bone marrow cells (BM) and spleen cells (SP) from C57BL/6N mice, no significant difference was found in severity of aGVHD or survival rate between the two groups of mice. However, MIF level had decreased at 1 week after HSCT when MIF KO mice were used as the recipients. In the experiment using MIF KO mice as the donors, the recipient mice transplanted with BM and SP from MIF KO mice had significantly lower aGVHD scores on days 14, 21, and 35 than those in the recipient mice transplanted with BM and SP from WT-BALB/c mice. Histopathological findings supported these observations, showing that the bile ducts and lobules in the liver were destroyed by infiltrating MIF-expressing lymphocytes in the recipients of BM and SP from WT-BALB/c mice, while the bile ducts were not destroyed even by infiltrating MIF-deficient lymphocytes in the recipients of BM and SP from MIF KO mice. Therefore, these findings suggest that MIF has an effect on the development of aGVHD in a murine model of allogeneic stem cell transplantation.

Acute Disease↗
PubMed2006

Effect of chlorpromazine on bone sialoprotein (BSP) gene transcription.

Bone sialoprotein (BSP), an early marker of osteoblast differentiation. Whereas physical forces may play an important role in the regulation of bone cell function, little is known about how cells are able to sense mechanical loads. Chlorpromazine, a tranquilizing agent for treatments of psychiatric disorders, mimics hypotonic stress and causes membrane deformation. Application of 10 microg/ml of chlorpromazine suppressed BSP mRNA levels after 12 and 24 h in osteoblast-like ROS17/2.8 cells and rat stromal bone marrow cells (SBMC-D8). Chlorpromazine (10 microg/ml) decreased luciferase activity of the construct (pLUC3; -116 to +60 of the rat BSP gene promoter) after 12 h, the effect was inhibited by the tyrosine kinase inhibitor herbimycin A (HA) and MAP kinase kinase inhibitor U0126. Introduction of 2-bp mutation in the pLUC3 construct showed that the chlorpromazine effects were mediated by cAMP response element (CRE) and FGF2 response element (FRE). In gel shift assays, using radiolabeled double-stranded CRE and FRE oligonucleotides, which revealed decreased binding of nuclear proteins from chlorpromazine-stimulated cells. These studies, therefore, show that chlorpromazine suppresses BSP gene transcription through tyrosine and MAP kinases-dependent pathways and that the chlorpromazine effects are mediated by CRE and FRE elements in the proximal promoter of the BSP gene.

Animals↗
PubMed2006

Fibroblast growth factor 2 and cyclic AMP synergistically regulate bone sialoprotein gene expression.

Bone sialoprotein (BSP) is a noncollagenous protein of the mineralized bone extracellular matrix. We here report that FGF2 and cAMP act synergistically to stimulate BSP gene expression. Treatment of ROS 17/2.8 cells with either 10 ng/ml FGF2 or 1 microM FSK for 6 h resulted in 5.4- and 8.2-fold increases, respectively, in the levels of BSP mRNA. However, in the presence of both FGF2 and forskolin (FGF/FSK), BSP mRNA levels were increased synergistically by 20.4-fold. Using a luciferase reporter construct, encompassing BSP promoter nucleotides -116 to +60, transcription was also increased synergistically by 15.0-fold with FGF/FSK, compared to stimulations of 2.6- and 5.3-fold, respectively, for FGF2 and FSK alone. Transcriptional stimulation by FGF/FSK abrogated in constructs included 2 bp mutations in the inverted CCAAT, CRE, FRE and Pit-1 elements. Whereas the FRE-protein complex was increased by FGF2 and FGF/FSK, the Pit-1-protein complex was decreased by FSK and FGF/FSK. Notably, transcriptional activity induced by FGF/FSK was blocked by protein kinase A, tyrosine kinase and MEK inhibitors. These studies indicate that the combinatorial effects of FGF and FSK act through PKA, tyrosine kinase and MAP-kinase-dependent pathways, which target the inverted CCAAT, CRE, FRE and Pit-1 elements in the BSP gene to synergistically increase BSP expression.

Animals↗
PubMed2006

Regulation of bone sialoprotein (BSP) gene transcription by lipopolysaccharide.

Lipopolysaccharide (LPS) is a major mediator of inflammatory responses in periodontal disease that inhibits bone formation and stimulates bone resorption. To determine the molecular mechanisms involved in the suppression of bone formation, we have analyzed the effects of LPS on BSP gene expression. Bone sialoprotein (BSP) is a mineralized tissue-specific protein that appears to function in the initial mineralization of bone. Treatment of osteoblast-like ROS 17/2.8 cells with LPS (1 microg/ml) for 12 h caused a marked reduction in BSP mRNA levels. The addition of antioxidant N-acetylcysteine (NAC; 20 mM) 30 min prior to stimulation with LPS attenuated the inhibition of BSP mRNA levels. Transient transfection analyses, using chimeric constructs of the rat BSP gene promoter linked to a luciferase reporter gene, revealed that LPS (1 microg/ml) suppressed expression of luciferase construct, encompassing BSP promoter nucleotides -108 to +60, transfected into ROS17/2.8 cells. The effects of LPS were inhibited by protein kinase A (PKA) inhibitor, H89 and the tyrosine kinase inhibitor, herbimycin A (HA). Introduction of 2 bp mutations in the inverted CCAAT box (ATTGG; nts -50 and -46), a cAMP response element (CRE; nts -75 to -68), a FGF response element (FRE; nts -92 to -85), and a pituitary specific transcription factor binding element (Pit-1; nts -111 to -105) showed that the LPS effects were mediated by the CRE and FRE. Whereas the FRE and 3'-FRE DNA-protein complexes were decreased by LPS, CRE DNA-protein complex did not change after LPS treatment. These studies, therefore, show that LPS suppresses BSP gene transcription through PKA and tyrosine kinase-dependent pathways and that the LPS effects are mediated through CRE and FRE elements in the proximal BSP gene promoter.

Animals↗
PubMed2006

Insulin-like growth factor-I increases bone sialoprotein (BSP) expression through fibroblast growth factor-2 response element and homeodomain protein-binding site in the proximal promoter of the BSP gene.

Insulin-like growth factor-I (IGF-I) promotes bone formation by stimulating proliferation and differentiation of osteoblasts. Bone sialoprotein (BSP), is thought to function in the initial mineralization of bone, is selectively expressed by differentiated osteoblast. To determine the molecular mechanism of IGF-I regulation of osteogenesis, we analyzed the effects of IGF-I on the expression of BSP in osteoblast-like Saos2 and in rat stromal bone marrow (RBMC-D8) cells. IGF-I (50 ng/ml) increased BSP mRNA levels at 12 h in Saos2 cells. In RBMC-D8 cells, IGF-I increased BSP mRNA levels at 3 h. From transient transfection assays, a twofold increase in transcription by IGF-I was observed at 12 h in pLUC3 construct that included the promoter sequence from -116 to +60. Effect of IGF-I was abrogated by 2-bp mutations in either the FGF2 response element (FRE) or homeodomain protein-binding site (HOX). Gel shift analyses showed that IGF-I increased binding of nuclear proteins to the FRE and HOX elements. Notably, the HOX-protein complex was supershifted by Smad1 antibody, while the FRE-protein complex was shifted by Smad1 and Cbfa1 antibodies. Dlx2 and Dlx5 antibodies disrupted the formation of the FRE- and HOX-protein complexes. The IGF-I effects on the formation of FRE-protein complexes were abolished by tyrosine kinase inhibitor herbimycin A (HA), PI3-kinase/Akt inhibitor LY249002, and MAP kinase kinase inhibitor U0126, while IGF-I effects on HOX-protein complexes were abolished by HA and LY249002. These studies demonstrate that IGF-I stimulates BSP transcription by targeting the FRE and HOX elements in the proximal promoter of BSP gene.

Animals↗
PubMed2006

Mechanisms of giant papillary formation in vernal keratoconjunctivitis.

PURPOSE: Tissue remodeling, known to accompany exacerbation of bronchial asthma (BA) and characterized by thickening of reticular basement membrane, increased fibrosis, and angiogenesis, is believed to be an important mechanism in giant papillary formation in vernal keratoconjunctivitis (VKC). This study was conducted to confirm the difference of tissue remodeling between BA and VKC and to determine the most relevant factor for VKC exacerbation. METHODS: Histopathologic analysis of conjunctival specimens from 6 patients with VKC and 4 normal controls was performed. Immunohistochemistry tests for collagen types 1, 3, and 5, fibronectin, laminin (a marker of the basement membrane of the epithelium or vessels), fibroblast (prolyl 4-hydroxylase), and alpha-smooth muscle actin (alpha-SMA) were performed. Morphometric analysis evaluated immunoreactive areas for collagens and fibronectin and the number of cell nuclei in VKC papillae and normal control specimens. RESULTS: In histopathologic sections of VKC papillae, mononuclear cells were mainly observed in the central region and granulocytes preferentially in the peripheral stroma. Immunohistochemistry showed increased vascularity and existence of fibroblasts and alpha-SMA-positive cells in VKC papillae. Morphometric analysis showed that the number of cell nuclei in VKC papillae was 7.3 times higher versus in normal controls (P < 0.05). Furthermore, the immunoreactive area for fibronectin was 4.5 times larger versus in normal controls (P < 0.05), although collagens were not significantly different between the 2 groups. CONCLUSION: Giant papillary formation in VKC is thought to occur in relation to tissue remodeling. However, the most relevant factor for the exacerbation of VKC seems to be inflammation rather than fibrosis.

Actins↗
PubMed2006

The spectrum of cutaneous lymphomas in Japan: a study of 62 cases based on the World Health Organization Classification.

BACKGROUND: The relative incidence of malignant lymphoma subtypes differs according to geographic location. This study investigated the epidemiology of cutaneous lymphoma subtypes in Japan and compared it with other countries. METHODS: Sixty-two patients with cutaneous lymphoma attending the Department of Dermatology, National Hospital Organization Hokkaido Cancer Center were reviewed. The World Health Organization classification of hematopoietic and lymphoid malignancies was adopted. RESULTS: Of the 62 patients, 31 had primary cutaneous lymphoma (PCL) and 31 had secondary cutaneous lymphoma (SCL). T- and natural killer (NK)-cell lymphoma accounted for 80% of PCL, of which, mycosis fungoides accounted for almost 35%. Of the 31 patients with secondary cutaneous lymphoma, 17 patients (54%) had T- and NK-cell lymphoma, including nine adult T-cell leukemia/lymphoma patients, and 14 patients (46%) had B-cell lymphoma, including 11 diffuse large B-cell lymphoma patients. The majority of patients with SCL and NK-cell lymphoma with primary or secondary skin lesions had a poor outcome. CONCLUSIONS: PCL in this study showed a similar incidence to that of other institutions in Japan, while also demonstrating different frequencies from that of other countries, suggesting that the relative frequency of different PCL subtypes differ according to geographical location, similar to previous reports of systemic malignant lymphoma.

Adult↗
PubMed2006

[Relationship between abnormalities of genes involved in DNA damage responses and malignant tumors/autoimmune diseases].

The maintenance of genomic stability is an essential cellular function for a variety of well-coordinated regulation of biological activities of organisms, and a failure in its function results in the accumulation of mutations and/or abnormality in the induction of apoptosis, eventually leading to onsets of various diseases, including malignant tumors. DNA damage responses, in particular cell-cycle checkpoint regulation, play important roles in maintaining genomic integrity. In response to DNA damages induced by gamma-irradiation, ultraviolet irradiation, various chemicals, or reactive oxygen species (ROS), intrinsic cell-cycle checkpoint machinery is rapidly activated to arrest cells at particular cell-cycle points, and during cell-cycle checkpoint arrest cells may try to repair damaged DNAs, and then re-start cell-cycle upon the completion of DNA repair. Alternatively, if the extents of DNA damage overwhelm the capacity of the cellular repair machinery, cells may undergo apoptosis to prevent the accumulation of mutations within the organisms. In this article, we will first explain about our current view of DNA damage responses, in particular cell-cycle checkpoint regulation, and summarize our knowledge of the relationships between abnormalities of genes involved in DNA damage responses and malignant tumors, including hematopoietic malignancies. We will also discuss a possible implication of DNA damage responses in autoimmune diseases, such as rheumatoid arthritis.

Apoptosis↗
PubMed2005

The immunosuppressive agent FK506 enhances the cytolytic activity of inhibitory natural killer cell receptor (CD94/NKG2A)-expressing CD8 T cells.

Tacrolimus (FK506) is a potent immunosuppressive agent that inhibit transcription of cytokines such as IL-2 in T cells. The C-type lectin superfamily inhibitory NKR CD94/NKG2A-expressing cells can monitor the global status of HLA class I on tumor and leukemic cells through the recognition of HLA-E and induce cytolytic attack without an inhibitory signal against HLA class I-decreased target cells. We found that there was no effect of FK506 on the expansion of inhibitory NKR CD94/NKG2A-expressing T cells from granulocyte colony-stimulating factor (G-CSF)-mobilized peripheral blood mononuclear cells (G-PBMCs). However, cytolytic activity levels of purified CD94-expressing cells from 7-day cultures with FK506 were much higher than those from 7-day cultures without FK506. These data suggested that FK506 did not inhibit cytolytic activities of inhibitory NKR-expressing T cells and that there was a possibility of cytolytic activities being enhanced through the induction of cytotoxic molecules such as NKG2D and granzyme during a seven-day culture with FK506.

CD8-Positive T-Lymphocytes↗
PubMed2005

Immune responses to oral infection with Echinococcus multilocularis protoscoleces in gerbils: modified lymphocyte responses due to the parasite antigen.

Immune responses to oral infection with Echinococcus multilocularis protoscoleces in Mongolian gerbils were investigated. Gerbils not treated with prednisolone expelled most of the parasites within 3 days post-infection and induced parasite-specific intestinal IgA secretion after the oral inoculation with protoscoleces. In contrast, prednisolone-treated gerbils harbored notable numbers of parasites, and the parasite-specific intestinal IgA secretion was lower. In gerbils not treated and orally inoculated with protoscoleces (infected group), parasite-specific antibody levels in sera and intestinal washings were elevated, but blastogenesis against protoscolex antigens was observed only in cells from Peyer's patches at 14 days post-infection. Concanavalin A-induced proliferative lymphocytes from both infected and naive gerbils were suppressed by adding protoscolex somatic antigen. These data indicate that while parasite-specific antibody responses were observed, lymphocyte proliferative responses were suppressed by parasite infection/antigens in the Mongolian gerbil, prednisolone-untreated rodent definitive host model.

Administration, Oral↗
PubMed2005

Modified cellular immune responses in dogs infected with Echinococcus multilocularis.

Parasite-specific antigen responses and lymphocyte blastogenesis in dogs orally inoculated with Echinococcus multilocuralis metacestodes were examined. Serum IgG1 (Th2-oriented) and IgG2 (Th 1-oriented) levels against somatic and excretory-secretory (ES) antigens of protoscoleces and adult worms increased from 7 days post-infection (DPI), with the highest responses against protoscolex excretory-secretory antigen (PES). Specific blastogenesis of peripheral blood mononuclear cells (PBMC) against the parasite antigens was not observed during the 21-day infection period, but Peyer's patches cells from one out of two dogs at 21 DPI showed blastogenesis against PES (stimulation index: 4.65). Interestingly, only at 7 DPI were concanavalin A (ConA)-induce proliferative responses of PBMC reduced. Moreover, ConA-induced proliferative responses of lymphocytes from various origins were suppressed by the addition of parasite antigens, especially with PES. These data suggest that although both Th1- and Th2-oriented humoral immune responses were observed in E. multilocularis infected dogs, the parasite antigens, especially PES, may have incompletely suppressed lymphocyte responses in these dogs.

Animals↗
PubMed2005

A randomized controlled trial of Japanese patients with obsessive-compulsive disorder--effectiveness of behavior therapy and fluvoxamine.

BACKGROUND: The aim of this study was to confirm and compare the efficacy of fluvoxamine (the only licensed SSRI for treatment for OCD in Japan) and behavior therapy in treating Japanese patients with OCD. In addition, we investigated predictors of these treatments. METHODS: Thirty-one outpatients meeting the DSM-III-R criteria for OCD without any axis I disorder were randomly assigned to one of three treatment conditions: BT (behavior therapy +/- pill placebo), FLV [autogenic training (a psychological placebo for OCD) +/- fluvoxamine] and control group [autogenic training (psychological placebo) +/- pill placebo] for 12 weeks of treatment. The Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) and the Clinical Global Impression-Improvement Scale (CGI-I) were administered blindly at baseline and week 4, 8 and 12. RESULTS: Twenty-eight patients completed this study. Patients in the BT and FLV groups showed significantly more improvement than those in the control group in the mean score of total Y-BOCS; moreover, the BT group showed significantly more reduction in total Y-BOCS score at the end of treatment than the FLV group (BT > FLV, p < 0.01). Patients with lower baseline total Y-BOCS, past history of a major depressive episode and absence of cleaning compulsion improved more with fluvoxamine. CONCLUSIONS: We confirmed the effectiveness of behavior therapy and fluvoxamine for Japanese patients with OCD. Behavior therapy improved the condition of OCD patients more than fluvoxamine.

Adolescent↗
PubMed2005

Amelogenin stimulates bone sialoprotein (BSP) expression through fibroblast growth factor 2 response element and transforming growth factor-beta1 activation element in the promoter of the BSP gene.

BACKGROUND: Amelogenins are a complex mixture of hydrophobic proteins that are the major organic component of developing enamel. The principal function of the amelogenins and their degradation products has been assigned to structural roles in creating the space and milieu for promoting enamel mineralization. Enamel matrix derivative (EMD) has been used clinically for periodontal regeneration and its therapeutic effectiveness has been attributed to amelogenin, non-amelogenin enamel matrix proteins, and growth factors. While EMD is believed to induce periodontal regeneration, the precise mechanism is not known. Bone sialoprotein (BSP), an early phenotypic marker of osteoblast and cementoblast differentiation, has been implicated in the nucleation of hydroxyapatite during bone formation. In this study, we examined the ability of amelogenin to regulate BSP gene transcription in osteoblast like cells. METHODS: We conducted Northern hybridization, transient transfection analyses, and gel mobility shift assays using full-length recombinant amelogenin to determine the molecular basis of the transcriptional regulation of BSP gene by amelogenin. RESULTS: Recombinant amelogenin (1 microg/ml, 12 hours) increased BSP mRNA levels approximately 2.4-fold. In transient transfection analyses, amelogenin (1 microg/ml, 12 hours) increased luciferase activity approximately 1.5-fold in pLUC3 (nucleotides -116 to +60) and further increased pLUC5 (nucleotides -801 to +60) activity approximately 2.3-fold transfected into ROS 17/2.8 cells. Amelogenin also increased luciferase activities in rat stromal bone marrow cells. The effect of amelogenin was inhibited by the tyrosine kinase inhibitor herbimycin A. Transcriptional stimulation by amelogenin was almost completely abrogated in cells expressing a BSP promoter construct with a mutation in the fibroblast growth factor 2 (FGF2) response element (FRE). Gel mobility shift assays with radiolabeled FRE and transforming growth factor-beta1 (TGF-beta1) activation element (TAE) ds-oligonucleotides revealed increased binding of nuclear proteins from amelogenin-stimulated ROS 17/2.8 cells. CONCLUSION: Amelogenin stimulation alters BSP gene transcription by inducing nuclear proteins that bind to the FRE and TAE in the rat BSP gene promoter.

Amelogenin↗