Functions of osteocytes in bone metabolism
| Project/Area Number |
07457431
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Morphological basic dentistry
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| Research Institution | Meikai University |
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Principal Investigator |
KUMEGAWA Masayoshi Meikai University School of Dentistry, Professor, 歯学部, 教授 (40049367)
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| Co-Investigator(Kenkyū-buntansha) |
MANO Hiroshi School of Dentistry, Meikai University, Assistant, 歯学部, 助手 (20265359)
HAKEDA Yoshiyuki School of Dentistry, Meikai University, Assistant Professor, 歯学部, 助教授 (90164772)
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| Project Period (FY) |
1995 – 1996
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| Project Status |
Completed (Fiscal Year 1996)
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| Budget Amount *help |
¥7,100,000 (Direct Cost: ¥7,100,000)
Fiscal Year 1996: ¥2,600,000 (Direct Cost: ¥2,600,000)
Fiscal Year 1995: ¥4,500,000 (Direct Cost: ¥4,500,000)
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| Keywords | Osteocytes / Inhibition of bone resorption / Rho-GDI like protein / Ca receptor / Vitamin D_3 / Pho-GDIタンパク質 / 破骨細胞抑制因子 |
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| Research Abstract |
I.In order to investigate roles of osteocytes in bone resorption, the homogenate and conditioned medium of purified chick calvarial osteocytes were examined in a pit formation assay using unfractionated bone cells from mice. The osteocyte homogenate markedly inhibited the pit formation, whereas the conditioned medium of the cells had no effect on the pit formatin. The inhibitory activity was not a result of cytotoxicity of the homogenate. In this study, a bone-resorption inhibitory protein was purified from collagenase-digested chick calvarial fragments enriched in osteocytes. The inhibitory protein, 18.5kDa, showed a significant dose-dependent inhibition of the pit formation by unfractionated bone cells from mice and rabbits, and by human giant cell tumor cells. This protein also inhibited the bone-resorbing activity of purified osteoclasts in the pit formation assay in the absence of other effector cells. Microinjection of the protein into osteoclasts caused disruption of the podosomes in the cells. The N-terminal 25-amino acid sequence of the protein was 68% homologous to a part of Rho-GDI.Osteocytes may be involved in the regulatory mechanism of bone resorption by osteoclasts.
II.Vitamin D_3 regulates the amount of calcium receptor (CaSR) mRNA Vitamin D_3 decreases the amount of CaSR mRNA in occipital bone, but the hormone increases that of CaSR mRNA in long bone and kidney. These results indicate the presence of tissue specific regulation in CaSR by Vitamin D_3.
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Report
(3 results)
Research Products
(8 results)
