| Project/Area Number |
17590394
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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 |
Bacteriology (including Mycology)
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| Research Institution | Ehime University |
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Principal Investigator |
SHINNOMIYA Hiroto Ehime University, Graduate School of Medicine, Associate Professor, 大学院・医学系研究科, 助教授 (80162618)
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| Co-Investigator(Kenkyū-buntansha) |
ASANO Yoshihiro Ehime University, Graduate School of Medicine, Professor, 大学院・医学系研究科, 教授 (70114353)
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| Project Period (FY) |
2005 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2006: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2005: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Keywords | p65 / L-plastin / cytoskeleton / macrophage / host defense / cell adhesion / phosphorylation / protein complex / p65-scaffold / 65 / 分子集合 / 接着分子 |
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| Research Abstract |
A 65-kDa protein was identified as a phosphorylated protein in bacterial LPS-stimulated macrophages in our previous study and has turned out to be a murine homologue of human L-plastin, a protein originally identified as a transformation-induced phosphoprotein in cancer cells. The p65/L-plastin is a member of the plastin family characterized by a series of Ca^<2+>, calmodulin, and b-actin binding domains. The L-isoform is exclusively expressed in leukocytes, suggesting it plays a vital role in cellular functions unique to leukocytes. In the present study, we have investigated the dynamics of p65/L-plastin when macrophage adhesion via integrins was remarkably increased by stimulation with LPS. An inhibitor of an LPS-inducible serine kinase phosphorylating p65/L-plastin inhibited both p65/L-plastin rearrangement and cellular adhesion. In this p65/L-plastin-involved adhesion, the protein was clearly observed to locate densely in podosome-like structures close to the substratum. The increased adhesion and the rearrangement of p65/L-plastin were also characteristic for b_2-integrin-positive cells accumulated in the spleen of mice infected with Salmonella organisms. in vitro kinase assay using peptide substrates revealed that the kinase activity phosphorylating the p65/L-plastin-peptides was augmented both in peritoneal macrophages stimulated in vitro with LPS and in CD11b-positive cells infiltrated in the Salmonella-infected spleen. Furthermore, generation of hydrogen peroxide, a bactericidal substance, was much higher in LPS-stimulated macrophages where p65/L-plastin was translocated than in resting macrophages. These findings suggest that p65/L-plastin and b-actin are closely coupled dynamically in macrophages in response to bacterial stimulation to organize adhesion structures containing integrins, and that this may also function as cytoskeletal scaffolds that effectively organize the anti-bacterial activities of macrophages.
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