Functions of osteocytes in bone metabolism

骨细胞在骨代谢中的功能

基本信息

批准号：
07457431
负责人：
KUMEGAWA Masayoshi
金额：
$ 4.54万
依托单位：
Meikai University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07457431/
关键词：
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

项目摘要

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.

I.为了研究骨细胞在骨吸收中的作用，使用来自小鼠的未分级骨细胞在坑形成试验中检查了纯化的鸡颅骨骨细胞的匀浆和条件培养基。骨细胞匀浆显着抑制小凹形成，而细胞条件培养基对小凹形成素没有影响。抑制活性不是匀浆细胞毒性的结果。在这项研究中，从富含骨细胞的胶原酶消化的鸡颅骨碎片中纯化出骨吸收抑制蛋白。抑制蛋白 18.5kDa 对小鼠和兔子的未分级骨细胞以及人巨细胞肿瘤细胞的小凹形成具有显着的剂量依赖性抑制作用。在没有其他效应细胞的情况下，该蛋白还在凹坑形成测定中抑制纯化的破骨细胞的骨吸收活性。将蛋白质显微注射到破骨细胞中会导致细胞中足体的破坏。该蛋白N端25个氨基酸序列与Rho-GDI部分有68%同源性。骨细胞可能参与破骨细胞骨吸收的调节机制。二、维生素D_3调节钙受体（CaSR）的量) mRNA 维生素 D_3 会降低枕骨中 CaSR mRNA 的量，但该激素会增加长骨和肾脏中 CaSR mRNA 的量。这些结果表明维生素 D_3 对 CaSR 存在组织特异性调节。