| Project/Area Number |
15590447
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Immunology
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| Research Institution | Research Institute, Osaka Medical Center for Cancer and Cardiovascular Diseases |
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Principal Investigator |
MATSUMOTO Misako Osaka Medical Center for Cancer, Dept.of Immunology, Researcher, 研究所, 部門長 (30332456)
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| Co-Investigator(Kenkyū-buntansha) |
SEYA Tsukasa Hokkaido University, Graduate School of Medicine, Dept.of Microbiology and Immunology, Professor, 大学院・医学研究科・病態制御医学講座, 教授 (10301805)
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| Project Period (FY) |
2003 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2004: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2003: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Keywords | Innate immunity / Toll-like receptor / Adaptor molecule / Dendritic cell / Type 1 interferon / double-stranded RNA / Viral infection / Interferon regulatory factor / Signal transduction |
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| Research Abstract |
Toll-like receptor 3(TLR3) recognizes dsRNA and transmits signals to activate NF-κB and the IFN-β promoter independent of the adaptor molecules MyD88 and Mal/TIRAP. We have identified an alternative adaptor, designated Toll-interleukin 1 receptor domain(TIR)-containing adaptor molecule (TICAM)-1, that can physically bind the TIR domain of TLR3 and activate the IFN-β promoter in response to poly(I:C), a syntetic analog of dsRNA. TICAM-1, when overexpressed, activated NF-κB and interferon regulatory factor(IRF)-3, a critically important transcription factor for IFN-β gene expression. RNA interference-mediated knockdown of TLR3 or TICAM-1, but not of MyD88 or Mal/TIRAP, significantly reduced IFN-β production induced by poly(I:C) in human fibloblasts and HeLa cells. Thus, dsRNA-TLR3-dependent production of IFN-β is mediated mainly by TICAM-1. Furthermore, we cloned an additional adaptor molecule, TICAM-2, that physically bridges TLR4 and TICAM-1 and functionally transmits LPS-TLR4 signaling to TICAM-1, which in turn activates IRF-3 leading to produce IFN-β. This TICAM-1-dependent pathway forms part of the MyD88-independent cellular immune response. Immunofluorescence staining and con focal microscopic analysis using anti-human TLR3 mAb (TLR3.7) revealed that TLR3 localized to specific unidentified intracellular vesicles in both monocyte-derived immature DCs and CD11c^+ blood DCs. TLR3-mediated signaling required endosomal maturation. These results suggest that the TLR3-TICAM-1 pathway plays an important role in sensing the extracellular dsRNA, which participates in an antiviral immune response.
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