1998 Fiscal Year Final Research Report Summary
Do bone cells have mechanosensor? Does Insulin-like growth factor-I play a role in signaltransduction of loading stress?
| Project/Area Number |
08671707
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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 | University of Occupational and Environmental Health |
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Principal Investigator |
NARUSAWA Ken'ichiro School of medicine, Assistant professor, 医学部, 助手 (20269062)
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| Co-Investigator(Kenkyū-buntansha) |
OISHI Yosuke School of medicine, Assistant professor, 医学部, 助手 (60233029)
OHNISHI Hideo School of medicine, Assistant professor, 医学部, 助手 (20279342)
NAKAMURA Toshitaka School of medicine, Professor, 医学部, 教授 (50082235)
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| Project Period (FY) |
1996 – 1998
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| Keywords | osteoblast / osteocyte / MG-63 cell / primary culture / Insulin-like growth factor-I / compression / mechanical stress / epithelial Na^+ channels |
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| Research Abstract |
In the present study the effects of mechanical compression on cell proliferation, DNA synthesis and protein synthesis were examined in vitro with the human osteoblast-like cell line MG-63 and mouse osteoblast primary culture.
Pressure was applied to cells by instilling compressed helium into sealed plates or flasks in which the partial pressure of oxygen were maintained constant. Compression resulted in time and intensity-dependent increases in cell number and [^3H]thymidine incorporation, with, maximum effects apparent at 10 min and 80 -l5OmmHg. However the effect was also seen at more intensive pressure, 76OmmHg, when cell were compressed with insulin-like growth factor-I.Compression-induced cell proliferation and DNA synthesis were not inhibited by gadolinium (Gd^<3+>), a blocker of stretch-activated
ion channels, or by inhibitors of protein kinase A, protein kinase C, or Ca^<2+>/calmodulin-dependent protein kinases. However, the tyrosine kinase inhibitor genistein or herbimycin A inhibited these effects of compression in a concentration-dependent manner, and also epithelial Na^+ channel blocker benzamil did. Conditioned medium obtained from cells 60 minutes after compression induced cell proliferation, but not from cells 30 or 120 minutes after compression. RT-PCR analysis revealed that MG-63 cells expressed osteocalcin twelve hours after compression.
We also examined bone nodule formed by the primary cultures of mixed osteoblast and osteocyte from mouse calvariae. Bone nodule formation with dialy compresion (l5OmmHg x 10 min x once / day) were increased 1.6 times as much as that without compression.
These results suggest that transmural compression affects epithelial Na^+ channel and then triggers the release of a autocrine-paracrine factor (or factors) that induces cell proliferation and bone matrix protein synthesis through a tyrosine kinase pathway, then eventually increases bone formation in bone cells.
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