| Project/Area Number |
13470388
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Morphological basic dentistry
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| Research Institution | Meikai University |
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Principal Investigator |
OHMORI Yoshihiro Meikai University, School of Dentistry, Professor, 歯学部, 教授 (50194311)
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| Project Period (FY) |
2001 – 2003
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| Project Status |
Completed (Fiscal Year 2003)
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| Budget Amount *help |
¥11,700,000 (Direct Cost: ¥11,700,000)
Fiscal Year 2003: ¥3,900,000 (Direct Cost: ¥3,900,000)
Fiscal Year 2002: ¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2001: ¥4,200,000 (Direct Cost: ¥4,200,000)
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| Keywords | Gene expression / Transcriptional regulation / STAT1 / NF-κB / Chemokine / Cytokine / Coactivator / Molecular Biology / 癌細胞 / Interferon-γ / MIG / CXCL9 / IP-10 / CXCL10 / 転写共役因子 |
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| Research Abstract |
Cytokine-mediated intercellular communication is often orchestrated through crosstalk between different classes of cytokines and extracellular stimuli. Interferon gamma (IFNγ) and tumor necrosis factor α (TNFα) or lipopolysaccharide (LPS) often cooperatively regulate the expression of many inflammatory gene expressions. In the present study we explored the mechanisms through which coactivator CREB-binding protein (CBP) integrates the crosstalk between IFNγ/STATI and TNFα/NF-κB signaling pathways to cooperatively induce the transcriptional activation of the gene for CXCL9, an IENγ-inducible chemokine. Experiments with CBP mutants indicated that the N-terminal and C-terminal regions were necessary for the transcriptional synergy, although the histone acetyltransferase activity of CBP was dispensable. Co-immunoprecipitation assay demonstrated that STAT1 and NF-κB RelA(p65) simultaneously associated with CBP in vivo. Furthermore, chromatin immunoprecipitation revealed that costimulation wi
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th IFNγ and TNFα resulted in increased recruitment of STAT1, CBP and RNA polymerase II at the promoter region of the CXCL 9 gene. These results demonstrate that the STAT1/NF-κB-dependent transcriptional synergy results from the enhanced recruitment of RNA polymerase II complex to the promoter via simultaneous interaction of CBP with STAT1 and NF-κB.
In this study, we also examined the role of mitogen-activated protein (MAP) kinase in STAT1 and NE-κB-mediated transcriptional synergy in LPS and IFNγ-stimulated macrophages. P38 MAP kinase inhibitor SB203580 markedly suppressed expression of CXCL9 mRNA in macrophage-like RAW264.7 cells stimulated with LPS and IFNγ. The inhibitory effect was at transcriptional level because reporter gene analysis using a CXCL9 promoter construct also showed that IFNγ and LPS-induced synergistic promoter activity was suppressed by SB203580. These results indicate that p38 MAP kinase is involved in the IFNγ-and LPS-induced transcriptional synergy.
Finally, we evaluated the IFNγ-induced expression of CXCL9 and CXCL10 genes in several human tumor cell lines and found that these chemokine genes were not inducible by IFNγ in human squamous carcinoma line Ca9-22 and human glioma cell line A172. However, the impairment for the expression was not due to any defect in IFNγ-activated STAT1. Instead, constitutive NF-κB activity, which was seen in cells that expressed the IFNγ-induced CXCL9 and CXCL10 genes, was absent in Ca9-22 and A172 cells. Our data indicate that constitutive NF-κB activity is a critical determinant for the expression of the IFNγ-induced anti-tumor chemokines CXCL9 and CXCL10 and that downregulation of constitutive NF-κB activity may inhibit the expression of these IFNγ-inducible chemokines in human tumor cells. Less
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