Kenji Ishihara

Tohoku University, Sendai-shi, Miyagi-ken, Japan

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Publications (36)93.94 Total impact

  • Article: Induction of thymic stromal lymphopoietin production by xylene and exacerbation of picryl chloride-induced allergic inflammation in mice.
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    ABSTRACT: Some chemical compounds in the environment worsen allergic inflammation. In this study, we examined whether organic solvents induce the production of thymic stromal lymphopoietin (TSLP) which elicits Th2-type immune responses. Organic solvents were painted on the earlobes of BALB/c mice. The expression of TSLP in the ear was determined by ELISA. Xylene and toluene, but not chloroform or ethyl acetate, induced the expression of mRNA for TSLP in the earlobe tissue. Among the aromatic compounds, xylene, especially m-xylene, and trimethylbenzene caused apparent TSLP production. The level of TSLP in the xylene-treated earlobes reached a maximum at 24 h, and TSLP was expressed in epithelial tissues. Production of TSLP was unaffected in mast cell-deficient W/W(v) mice but apparently diminished in TNF-α knockout mice and IL-4 receptor knockout mice. Repeated painting of xylene for 7 days induced an increase in the weight of cervical lymph nodes and expression of OX40 ligand, both of which were inhibited in TSLP receptor knockout mice. Xylene promoted the picryl chloride-induced thickening of the ear and IL-4 production, which were reversed in TSLP receptor knockout mice. Xylene induced TSLP production, resulting in an exacerbation of allergic inflammation. Thus, xylene might be a good tool for examining the roles of TSLP in eliciting allergy in experimental animals.
    International Archives of Allergy and Immunology 01/2012; 157(2):194-201. · 2.40 Impact Factor
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    Article: Induction of thymic stromal lymphopoietin by chemical compounds in vivo and exacerbation of allergy
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    ABSTRACT: Exposure to several chemical compounds in the environment might worsen allergies. However, it remains unclear which chemicals except for contact-sensitizing compounds mod-ify inflammatory and immune responses and how. Thymic stromal lymphopoietin (TSLP), an IL-7-like cytokine produced mainly by epithelial cells, plays important roles in the initiation of allergic inflammation. We found that the painting of xylene on ear lobes induced produc-tion of TSLP and exacerbated the picryl chloride-induced allergic dermatitis. Thus, there are chemical compounds in the environment which do not have contact-sensitizing activity but cause the production of TSLP and on exacerbation of allergic dermatitis.
    Inflammation and Regeneration 04/2011; 31.
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    Article: Assessment of the release of nickel from biomaterials in vivo and in vitro: enhancement by lipopolysaccharide
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    ABSTRACT: Biodevices are implanted for long periods of time, so the release of metal ions from alloys should be tested in tissues to assess the risk of inducing metal allergies. However there is little evidence that the release of metal ions from alloys in vivo is similar to that in vitro. We im-planted metal wires in mice and determined the concentration of metal ions in tissue to ana-lyze the mechanisms responsible for metal allergies. The release of ions from the Ni wire was detected within 8 h and attained a plateau 72 h after the implantation. Furthermore, it was sig-nificantly increased by an injection of LPS. The results indicated that the release of Ni was apparently enhanced by inflammatory responses. We also established an in vitro assay system using the murine macrophage cell line RAW 264. The addition of LPS apparently increased the amount of Ni released into the medium, indicating the activation of the cells to have en-hanced the elution of ions from the Ni plate. Our in vitro model using LPS-stimulated RAW264 cells might reflect the elution of Ni in inflamed tissue.
    Inflammation and Regeneration 04/2011; 31.
  • Article: Suppression of intracellular calcium levels and inhibition of degranulation in RBL-2H3 mast cells by the sesquiterpene lactone parthenolide.
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    ABSTRACT: Pretreatment with parthenolide for 60 min inhibited the antigen-induced degranulation of RBL-2H3 mast cells; the IC(50) value being 4.5 ± 0.4 µM. The inhibition was not due to suppression of the phosphatidylinositol 3-kinase pathway because the antigen-induced phosphorylation of Akt was not inhibited by parthenolide. The antigen-induced increase in intracellular calcium levels was prevented by parthenolide, suggesting that parthenolide inhibited the antigen-induced degranulation by suppressing an increase in intracellular calcium levels. In support of this, parthenolide was found to prevent ionomycin-induced degranulation by inhibiting an increase in intracellular calcium levels. Therefore, parthenolide inhibits the degranulation of mast cells by preventing an increase in intracellular calcium levels.
    Planta Medica 02/2011; 77(3):252-6. · 2.15 Impact Factor
  • Article: Enhancement of nickel elution by lipopolysaccharide-induced inflammation.
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    ABSTRACT: Implantations of metallic biomedical devices into bodies are increasing. The elution of Ni ions from these devices can lead to metal allergies. However, the molecular mechanisms of the elution have not been fully examined. Furthermore, it is not clear whether infection and inflammation affect the corrosion of metals. We examined whether the elution of Ni from metal wires and plates was enhanced by inflammation in vivo and in vitro. A Ni or SUS316L wire was implanted subcutaneously in the dorsum of mice. Lipopolysaccharide (LPS) was injected at the site immediately following the implantation. After 8, 24, and 72 h, the tissue around the wire was excised. RAW 264 cells were seeded on a Ni plate and incubated for 24h in medium containing LPS. The amount of Ni in the tissue or conditioned medium was determined fluorometrically. The release of Ni ions from the wire was significantly increased from 8 to 72 h, and further increased by LPS. LPS also enhanced the release of Ni ions by the cells, but only when they were attached to the Ni plate. Chloroquine, bafilomycin A(1) and amiloride markedly inhibited the effects of LPS. The activation of inflammatory cells on metals enhanced the elution of Ni probably via the release of protons at the interface of the cells and material.
    Journal of dermatological science 01/2011; 62(1):50-7. · 3.71 Impact Factor
  • Article: Salicylate restores transport function and anion exchanger activity of missense pendrin mutations.
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    ABSTRACT: The SLC26A4 gene encodes the transmembrane protein pendrin, which is involved in the homeostasis of the ion concentration of the endolymph of the inner ear, most likely by acting as a chloride/bicarbonate transporter. Mutations in the SLC26A4 gene cause sensorineuronal hearing loss. However, the mechanisms responsible for such loss have remained unknown. Therefore, in this study, we focused on the function of ten missense pendrin mutations (p.P123S (Pendred syndrome), p.M147V (NSEVA), p.K369E (NSEVA), p.A372V (Pendred syndrome/NSEVA), p.N392Y (Pendred syndrome), p.C565Y (NSEVA), p.S657N (NSEVA), p.S666F (NSEVA), p.T721M (NSEVA) and p.H723R (Pendred syndrome/NSEVA)) reported in Japanese patients, and analyzed their cellular localization and anion exchanger activity using HEK293 cells transfected with each mutant gene. Immunofluorescent staining of the cellular localization of the pendrin mutants revealed that p.K369E and p.C565Y, as well as wild-type pendrin, were transported to the plasma membrane, while 8 other mutants were retained in the cytoplasm. Furthermore, we analyzed whether salicylate, as a pharmacological chaperone, restores normal plasma membrane localization of 8 pendrin mutants retained in the cytoplasm to the plasma membrane. Incubation with 10 mM of salicylate of the cells transfected with the mutants induced the transport of 4 pendrin mutants (p.P123S, p.M147V, p.S657Y and p.H723R) from the cytoplasm to the plasma membrane and restored the anion exchanger activity. These findings suggest that salicylate might contribute to development of a new method of medical treatment for sensorineuronal hearing loss caused by the mutation of the deafness-related proteins, including pendrin.
    Hearing research 12/2010; 270(1-2):110-8. · 2.18 Impact Factor
  • Article: Salicylate-induced translocation of prestin having mutation in the GTSRH sequence to the plasma membrane.
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    ABSTRACT: Prestin is a key molecule for mammalian hearing. The present study investigated changes in characteristics of prestin by culturing prestin-transfected cells with salicylate, an antagonist of prestin. As a result, the plasma membrane localization of prestin bearing a mutation in the GTSRH sequence, which normally accumulates in the cytoplasm, was recovered. Moreover, the nonlinear capacitance of the majority of the mutants, which is a signature of prestin activity, was also recovered. Thus, the present study discovered a new effect of salicylate on prestin, namely, the promotion of the plasma membrane expression of prestin mutants in an active state.
    FEBS letters 04/2010; 584(11):2327-32. · 3.54 Impact Factor
  • Article: Involvement of prostaglandins and histamine in nickel wire-induced acute inflammation in mice.
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    ABSTRACT: The irritancy of Nickel (Ni) ions has been well documented clinically. However, the chemical mediators involved in the acute inflammation induced by solid Ni are not fully understood. We used the Ni wire-implantation model in mice and examined roles of prostaglandins and histamine in plasma leakage in the acute phase. The subcutaneous implantation of a Ni wire into the back of mice induced plasma leakage from 8 to 24 h and tissue necrosis around the wire at 3 days, whereas the implantation of an aluminum wire induced no such inflammatory responses. An increase in the mRNA for cyclooxygenase (COX)-2 and HDC in cells around the Ni wire was detected 4 h after the implantation. The leakage of plasma at 8 h was inhibited by indomethacin in a dose-dependent manner. Dexamethasone and the p38 MAP kinase inhibitor SB203580 also inhibited the exudation of plasma consistent with the inhibition of the expression of COX-2 mRNA. Furthermore, plasma leakage was partially but siginificantly reduced in histamine H1 receptor knockout mice and histidine decarboxylase (HDC) knockout mice but not in H2 receptor knockout mice. These results suggested that the Ni ions released from the wire induced the expression of COX-2 and HDC, resulting in an increase in vascular permeability during the acute phase of inflammation.
    Journal of Biomedical Materials Research Part A 10/2009; 93(4):1306-11. · 2.63 Impact Factor
  • Article: Enhancement of ligand-dependent down-regulation of glucocorticoid receptor by lipopolysaccharide.
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    ABSTRACT: The inhibitory actions of glucocorticoids are often attenuated in inflamed tissues. The aim of the present study was to investigate whether the dexamethasone-induced downregulation of glucocorticoid receptor (GR) expression was enhanced by the stimulation with lipopolysaccharide (LPS). Various cells were stimulated with LPS (1microg/ml) for 30min and then treated with dexamethasone (1microM) for specified periods. The levels of GR and the phosphorylation at Ser211 were determined by Western blot. The effects of kinase inhibitors and a proteasome inhibitor on them were examined. The treatment of NCI-H292 cells with dexamethasone reduced the levels of GR, and the pretreatment with LPS accelerated the reduction. Such an enhancement by LPS of the dexamethasone-induced downregulation was observed in the respiratory epithelial cell lines BEAS-2B and A549, but not in the keratinocyte-like cell line HaCaT, the hematopoietic cell lines U937, THP-1 and Eol-1, or in hepatocytoma HepG2 cells. The treatment with dexamethasone and LPS apparently decreased GR levels in the lungs of BALB/c mice but not in the liver. In NCI-H292 cells, the LPS-enhanced downregulation of GR expression was recovered by the proteasome inhibitor MG-132. SP600125, SB203580 and roscovitine but not U0126 inhibited the LPS-induced enhancement of both the phosphorylation and the downregulation of GR. These findings suggested that the ligand-dependent downregulation of GR expression via the proteasome was apparent in the respiratory epithelial cells and enhanced by lipopolysaccharide via the activation of p38 MAP kinase, c-Jun N-terminal kinase and cyclin-dependent kinases.
    Life sciences 10/2009; 85(15-16):578-85. · 2.56 Impact Factor
  • Article: Suppression of the antigen-stimulated RBL-2H3 mast cell activation by Artekeiskeanol A.
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    ABSTRACT: Effects of artekeiskeanol A, a newly isolated coumarin derivative from Artemisa keiskeana Miq. (Compositae), the extract of which is used for treatment of rheumatoid arthritis as a folk medicine, on the antigen-induced activation of RBL-2H3 cells were examined. RBL-2H3 cells were sensitized with dinitrophenol (DNP)-specific IgE, and then stimulated with the antigen DNP-conjugated human serum albumin (DNP-HSA). Artekeiskeanol A at 10 to 100 microM inhibited the antigen-induced degranulation in a concentration-dependent manner, the IC(50) value being 38.0 + or - 0.2 microM. Degranulation induced by thapsigargin or A23187 also was inhibited by artekeiskeanol A at 10 to 100 microM. The antigen-induced increase in the levels of mRNA for tumor necrosis factor (TNF)-alpha and interleukin (IL)-13 and phosphorylations of Akt, p38 mitogen-activated protein kinase (MAPK), c-Jun N-terminal kinase (JNK) and p44/42 MAPK were also suppressed by artekeiskeanol A. Our findings suggested that the effectiveness of the extract of A. keiskeana might partly be due to the inhibition of mast cell activation by artekeiskeanol A.
    Planta Medica 08/2009; 75(14):1494-8. · 2.15 Impact Factor
  • Article: Analysis of the mechanism for the development of allergic skin inflammation and the application for its treatment:establishment of a modified allergic dermatitis model in mouse ear lobes by application of 12-O-tetradecanoyl phorbol 13-acetate: putative involvement of thymic stromal lymphopoietin and roles of histamine.
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    ABSTRACT: We established a novel allergic dermatitis model in mouse ear lobes in which antigen-nonspecific inflammation was induced by painting 12-O-tetradecanoylphorbol 13-acetate (TPA) between sensitization and challenge with picryl chloride (PiCl). This model has an advantage for analyzing atopic dermatitis-like inflammation within a short period. Analysis of the time course changes in the PiCl-induced swelling showed that the allergic inflammation was shifted from a delayed-type response to a biphasic response consisting of a weak immediate-phase response and a late-phase response by painting with TPA. The application of TPA increased the PiCl-induced infiltration of eosinophils and mast cells at the inflammatory site and shifted the cytokine milieu from Th1 to Th2. The expression of the Th2-inducing cytokine thymic stromal lymphopoietin (TSLP) mRNA was also increased by TPA. These findings suggested that the induction of antigen-nonspecific inflammation by TPA before the antigen challenge enhanced the Th2 response and modified the PiCl-induced delayed type-hypersensitivity. Using this model, we clarified that histamine plays significant roles in the early-phase swelling via H(1) receptors and the late-phase swelling via H(3)/H(4) receptors. Thus, we suggested the usefulness of the combined treatment with an H(1) antagonist and an H(4) antagonist for the suppression of atopic dermatitis.
    Journal of Pharmacological Sciences 08/2009; 110(3):245-50. · 2.08 Impact Factor
  • Article: Effects of nickel on eosinophil survival.
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    ABSTRACT: Accessories, watches, coins and other items containing metal sometimes cause contact dermatitis and metal allergy. Among metals, nickel in alloys is ionized by sweat on the surface of the skin and exhibits particularly marked irritancy and allergenicity. Although eosinophils play important roles in allergy, the effects of nickel on eosinophils have not been elucidated. Eosinophils were prepared from the peritoneal cavity in rats immunized with Ascaris suum extract. Purified rat eosinophils were incubated in the presence of various kinds of metals including nickel. The viability of eosinophils was analyzed using a flow cytometer. When rat eosinophils were incubated for 3 days in the presence of nickel chloride at 30-1,000 microM, the viability of eosinophils was decreased in a concentration-dependent manner. Nickel chloride at 300 muM significantly increased the percentage of annexin V+ PI- eosinophils. The population of annexin V+ PI- eosinophils was also increased by nickel sulfate, cobalt chloride and zinc sulfate. The binding of nickel ions to eosinophils was detected by flow cytometer. Nickel ions bind to eosinophils and decrease the viability of eosinophils through the induction of apoptosis. Nickel ions may exhibit activity which modifies the function of eosinophils in allergy.
    International Archives of Allergy and Immunology 02/2009; 149 Suppl 1:57-60. · 2.40 Impact Factor
  • Article: Modification of the picryl chloride-induced allergic dermatitis model in mouse ear lobes by 12-O-tetradecanoylphorbol 13-acetate, and analysis of the role of histamine in the modified model.
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    ABSTRACT: In atopic dermatitis, inflammation induced by antigen-nonspecific stimuli further enhances the allergic inflammation. However, there is no experimental model in which allergic dermatitis is evoked where the inflammation has been induced by antigen-nonspecific stimuli. Here, we established a novel dermatitis model in mice and analyzed the role of histamine. After sensitization with picryl chloride (PiCl) by painting on ear lobes of cyclophosphamide-treated mice, 12-O-tetradecanoylphorbol 13-acetate (TPA) was painted twice at the same site, and then allergic inflammation was induced by painting PiCl. Histamine antagonists and cyclosporine A (CsA) were administered intravenously. The application of TPA shifted the PiCl-induced allergic inflammation from a delayed-type response to a biphasic response, increased the infiltration of eosinophils and mast cells at the inflammatory site, shifted the cytokine milieu from Th1 to Th2 and induced the expression of thymic stromal lymphopoietin in the ear lobes. The PiCl-induced increase in the thickness of the ear lobe in the immediate phase was suppressed by the H1 antagonist pyrilamine. In contrast, the increase in the swelling in the late phase and the infiltration of eosinophils were suppressed by the H3/H4 antagonist thioperamide. The inhibitory effect of the combined treatment with pyrilamine and thioperamide on the TPA-modified contact dermatitis was as potent as that of CsA. Induction of the antigen-nonspecific inflammation by TPA enhanced the PiCl-induced allergic inflammation. Histamine plays significant roles in the early-phase swelling via H1 receptors, and the late-phase swelling via H3/H4 receptors in this TPA-modified allergic dermatitis model.
    International Archives of Allergy and Immunology 12/2008; 148(4):279-88. · 2.40 Impact Factor
  • Article: Lead compounds for anti-inflammatory drugs isolated from the plants of the traditional oriental medicine in Korea.
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    ABSTRACT: Effects of compounds isolated from medicinal plants in Korea on prostaglandin E2 (PGE2) production in rat peritoneal macrophages were examined, and mechanism of action of the active constituents was analyzed. The active constituents were as follows; tectorigenin and tectoridin isolated from the rhizomes of Belamcanda chinensis, platycodin D isolated from the roots of Platycodon grandiflorum, imperatorin isolated from the roots of Angelica dahurica, and hyperin isolated from the roots of Acanthopanax chiisanensis. These compounds inhibit the induction of cyclooxygenase-2 (COX-2), thus inhibiting PGE2 production. The chemically synthesized chalcone derivative, 2'-hydroxy-4'-methoxychalcone, also inhibits PGE2 production by suppressing COX-2 induction. In contrast, taiwanin C isolated from the roots of Acanthopanax chiisanensis inhibited PGE2 production by direct inhibition of COX-1 and COX-2.
    Inflammation & Allergy - Drug Targets (Formerly ?Current Drug Targets - Inflammation & Allergy) 10/2008; 7(3):195-202.
  • Article: Effects of hyperin, isoquercitrin and quercetin on lipopolysaccharide-induced nitrite production in rat peritoneal macrophages.
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    ABSTRACT: The extract of the root of Acanthopanax chiisanensis Nakai is used for the treatment of inflammation. To analyse the action mechanism of this extract, the effect of hyperin (quercetin-3-O-beta-d-galactose) isolated from the ethyl acetate fraction of the root of A. chiisanensis on nitrite production and induction of inducible nitric oxide synthase (iNOS) in lipopolysaccharide (LPS, 1 microg/mL)-stimulated rat peritoneal macrophages were examined. The effect of the structurally related compounds, isoquercitrin (quercetin-3-O-beta-d-glucose) and quercetin (an aglycone of the two compounds) isolated from the extract of the leaves of Vaccinium koreanum Nakai was also examined to compare the effect. It was shown that hyperin inhibited the LPS-induced iNOS expression and nitrite production. Of the three compounds, quercetin showed the most potent inhibitory activity. The phosphorylation of p44/42 mitogen activated protein kinase (MAPK), p38 MAPK and c-Jun N-terminal kinase (JNK) were also inhibited by these compounds. These findings suggested that hyperin in the extract of the root of A. chiisanensis inhibits nitric oxide (NO) production through inhibition of the expression of iNOS by attenuation of p44/p42 MAPK, p38 MAPK and JNK, and thus participates in the antiinflammatory activity of the extract.
    Phytotherapy Research 09/2008; 22(11):1552-6. · 2.09 Impact Factor
  • Article: Mechanisms for the proliferation of eosinophilic leukemia cells by FIP1L1-PDGFRalpha.
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    ABSTRACT: The constitutively activated tyrosine kinase Fip1-like 1 (FIP1L1)-platelet-derived growth factor receptor alpha (PDGFRalpha) causes eosinophilic leukemia EoL-1 cells to proliferate. Recently, we demonstrated that histone deacetylase inhibitors suppressed this proliferation and induced the differentiation of EoL-1 cells into eosinophils in parallel with a decrease in the level of FIP1L1-PDGFRalpha. In this study, we analyzed the mechanism by which FIP1L1-PDGFRalpha induces the proliferation and whether the suppression of cell proliferation triggers the differentiation into eosinophils. The FIP1L1-PDGFRalpha inhibitor imatinib inhibited the proliferation of EoL-1 cells and decreased the level of the oncoprotein c-Myc as well as the phosphorylation of extracellular signal-regulated kinase and c-Jun N-terminal kinase (JNK). The proliferation of EoL-1 cells and expression of c-Myc were also inhibited by the MEK inhibitor U0126 and JNK inhibitor SP600125. The expression of the eosinophilic differentiation marker CCR3 was not induced by imatinib. These findings suggest that FIP1L1-PDGFRalpha induces the proliferation of EoL-1 cells through the induction of c-Myc expression via ERK and JNK signaling pathways, but is not involved in the inhibition of differentiation toward mature eosinophils.
    Biochemical and Biophysical Research Communications 03/2008; 366(4):1007-11. · 2.48 Impact Factor
  • Article: Mechanism for the decrease in the FIP1L1-PDGFRalpha protein level in EoL-1 cells by histone deacetylase inhibitors.
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    ABSTRACT: Acetylation and deacetylation of proteins occur in cells in response to various stimuli, and are reversibly catalyzed by histone acetyltransferase and histone deacetylase (HDAC), respectively. EoL-1 cells have an FIP1L1-PDGFRA fusion gene that causes transformation of eosinophilic precursor cells into leukemia cells. The HDAC inhibitors apicidin and n-butyrate suppress the proliferation of EoL-1 cells and induce differentiation into eosinophils by a decrease in the protein level of FIP1L1-PDGFRalpha without affecting the mRNA level for FIP1L1-PDGFRA. In this study, we analyzed the mechanism by which the protein level of FIP1L1-PDGFRalpha is decreased by apicidin and n-butyrate. EoL-1 cells were incubated in the presence of the HDAC inhibitors apicidin, trichostatin A or n-butyrate. The protein levels of FIP1L1-PDGFRalpha and phosphorylated eIF-2alpha were determined by Western blotting. Actinomycin D and cycloheximide were used to block RNA synthesis and protein synthesis, respectively, in the chasing experiment of the amount of FIP1L1-PDGFRalpha protein. When apicidin- and n-butyrate-treated EoL-1 cells were incubated in the presence of actinomycin D, the decrease in the protein level of FIP1L1-PDGFRalpha was significantly enhanced when compared with controls. In contrast, the protein levels were not changed by cycloheximide among these groups. Apicidin and n-butyrate induced the continuous phosphorylation of eIF-2alpha for up to 8 days. The decrease in the level of FIP1L1-PDGFRalpha protein by continuous inhibition of HDAC may be due to the decrease in the translation rate of FIP1L1-PDGFRA.
    International Archives of Allergy and Immunology 02/2008; 146 Suppl 1:7-10. · 2.40 Impact Factor
  • Article: Involvement of Na+/H+ exchangers in induction of cyclooxygenase-2 by vacuolar-type (H+)-ATPase inhibitors in RAW 264 cells.
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    ABSTRACT: In the mouse macrophage-like cell line RAW 264, vacuolar-type (H(+))-ATPase (V-ATPase) inhibitors, bafilomycin A(1) and concanamycin A, increased the level of cyclooxygenase (COX)-2 protein and its mRNA. The V-ATPase inhibitor-induced expression of COX-2 was suppressed by inhibitors of c-jun N-terminal kinase (JNK) and nuclear factor-kappaB, and by inhibitors of Na(+)/H(+) exchangers (NHEs). The bafilomycin A(1)-induced activation of JNK but not degradation of IkappaB-alpha was suppressed by NHE inhibitors and by an inhibitor of Na(+)/Ca(2+) exchanger SN-6. These results suggested that V-ATPase inhibitors induce the expression of COX-2 via NHE-dependent and -independent pathways.
    FEBS Letters 11/2007; 581(24):4633-8. · 3.54 Impact Factor
  • Article: Differentiation of eosinophilic leukemia EoL-1 cells into eosinophils induced by histone deacetylase inhibitors.
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    ABSTRACT: EoL-1 cells differentiate into eosinophils in the presence of n-butyrate, but the mechanism has remained to be elucidated. Because n-butyrate can inhibit histone deacetylases, we hypothesized that the inhibition of histone deacetylases induces the differentiation of EoL-1 cells into eosinophils. In this study, using n-butyrate and two other histone deacetylase inhibitors, apicidin and trichostatin A, we have analyzed the relationship between the inhibition of histone deacetylases and the differentiation into eosinophils in EoL-1 cells. It was demonstrated that apicidin and n-butyrate induced a continuous acetylation of histones H4 and H3, inhibited the proliferation of EoL-1 cells without attenuating the level of FIP1L1-PDGFRA mRNA, and induced the expression of markers for mature eosinophils such as integrin beta7, CCR1, and CCR3 on EoL-1 cells, while trichostatin A evoked a transient acetylation of histones and induced no differentiation into eosinophils. These findings suggest that the continuous inhibition of histone deacetylases in EoL-1 cells induces the differentiation into mature eosinophils.
    Life Sciences 04/2007; 80(13):1213-20. · 2.53 Impact Factor
  • Article: Inhibition of bone resorption in cultures of mouse calvariae by apicularen A.
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    ABSTRACT: Apicularens A and B were isolated from the myxobacterial genus Chondromyces apiculatus JW184. Apicularen A inhibited bafilomycin A1-sensitive ATP-dependent proton transport into microsome vesicles more potently than apicularen B. Bone resorption in cultures of mouse calvariae induced by human parathyroid hormone (PTH) or interleukin-1beta (IL-1beta) was inhibited by apicularen A at 10 and 100 nM, while apicularen B had no effect. The bisphosphonate incadronate inhibited bone resorption at 100 nM, being less effective than apicularen A. Our findings indicate that apicularen A inhibits bone resorption induced by PTH or IL-1beta more potently than apicularen B, probably due to inhibition of the V-ATPase.
    Planta Medica 03/2007; 73(2):173-5. · 2.15 Impact Factor