| Project/Area Number |
10671349
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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 |
Orthopaedic surgery
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| Research Institution | Tokyo Medical and Dental University |
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Principal Investigator |
OGATA Toshiko Tokyo Medical & Dental Univ., Medical Research Institute, assistant, 難治疾患研究所, 助手 (80014314)
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| Project Period (FY) |
1998 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥2,900,000 (Direct Cost: ¥2,900,000)
Fiscal Year 2000: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1999: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1998: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Keywords | Osteoblast / mechanical strain / egr-1 / ERK / Shc / Tyrosine-phosphorylation / proteolysis / EGFR / EGF / EGFリセプター / bFGF |
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| Research Abstract |
The architecture and homeostasis of bone are maintained under mechanical loading, but the mechanism is unclear. Fluid flow is a candidate of mediators transmiting mechanical loading to cells in bone. lpreviously found that in osteoblast-like cells, fluid flow of culture media induced an increase in egr-1 mRNA levels and that the induction was mediated by tyrosine kinase (s) and factor (s) in serum. Therefore, I examined what proteins were tyrosine-phosphorylated by media flow and what components of serum were needed in the induction. The studies were performed by immunoprecipitation and western blotting of cell-lysate before and after the flow was generated. The result showed that enhancement of tyrosine-phosphorylation of many proteins containing ERK1/2 and Shc was induced within a few minutes after the media flow. These responses were similar to those induced in the cells by growth factors. Therefore, I added EGF or basic-FGF in serum-free media. These growth factors recovered the responses, which were not observed in serum-free media. To clarify the role of EGF in these responses, I examined the alteration of EGF receptor after the media flow. I found that the amount of EGFR protein increased within 2 minutes after the media flow, peaked at about 10 minutes and returned to basal level at 60 minutes. This short response-time suggests that the increase of EGFR protein may be caused by decrease of proteolysis. In recent years, it has been elucidated that protease regulates various functions in life. Proteolysis may be also involved in signal transduction of mechanical strain. Clarifying what protease participates in this response may provide a clue to resolve how mechanical force stimulates bone cells.
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