| Project/Area Number |
16591860
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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 |
Functional basic dentistry
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| Research Institution | NAGASAKI UNIVERSITY |
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Principal Investigator |
SAKAI Eiko NAGASAKI UNIVERSITY, GRADUATE SCHOOL OF BIOMEDICAL SCIENCE, INSTRUCTOR, 大学院・医歯薬学総合研究科, 助手 (10176612)
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| Co-Investigator(Kenkyū-buntansha) |
KATO Yuzo NAGASAKI UNIVERSITY, GRADUATE SCHOOL OF BIOMEDICAL SCIENCE, PROFESSOR, 大学院・医歯薬学総合研究科, 教授 (20014128)
OKAMOTO Kuniaki NAGASAKI UNIVERSITY, GRADUATE SCHOOL OF BIOMEDICAL SCIENCE, ASSOCIATE PROFESSOR, 大学院・医歯薬学総合研究科, 助教授 (10311846)
FUKUMOTO Satoshi KYUSYU UNIVERSITY, GRADUATE SCHOOL OF DENTAL SCIENCE, ASSOCIATE PROFESSOR, 歯学研究院, 助教授 (30264253)
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| Project Period (FY) |
2004 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2005: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2004: ¥2,400,000 (Direct Cost: ¥2,400,000)
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| Keywords | OSTEOCLAST / LPS / GLYCOSPHINGOLIPID / LIPID RAFT / GM1 / TLR4 |
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| Research Abstract |
The lipid raft, is enriched in cholesterol and glycosphingolipids (GSLs), has been implicated as a functional microenviroment that regulates cellular signaling for various biological processes. Osteoclasts are monocyte/macrophage lineage multinucleated cells that play a critical role in bone resorption. Lipopolysaccharide (LPS), a major constituent of Gram-negative bacteria, has been suggested to be a survival factor of mature osteoclasts via Toll-like receptor 4. To clarify the role of GSLs in LPS mediated osteoclast survival, we used D-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol (D-PDMP), a glucosylceramide synthase inhibitor. Mature osteoclast survival by LPS was dramatically inhibited by D-PDMP in a dose dependent manner. Raft fraction of osteoclast was determined by the localization of ganglioside GM1 and flotillin-1 as raft markers. Raft fractionation of Triton X-100 extracts revealed that TLR4, MyD88, IRAK 1/4 and TRAF6 were recruited in raft fractions following LPS stimulation. These proteins were eliminated from raft fractions to non-raft fraction by D-PDMP treatment, however, by the addition of GM1 into culture medium, elimination of signaling molecules was canceled, and signaling molecules including TLR4, IRAK4, and TRAF6 were recruited in raft fraction again. Although the nuclear translocation of NF-κB promoted by LPS was inhibited by D-PDMP treatment, exogenous GSLs recovered the activation of NF-κB, and also osteocalst survival, suggesting the involvement of GSLs in LPS mediated osteoclast survival. GSLs have crucial roles for innate immune responses in mature osteoclast.
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