THE ELUCIDATION OF THE FUNCTION OF THE OSTEOCYTES AS CALCIUM SENSORY CELLS

骨细胞作为钙感觉细胞的功能的阐明

• 批准号: 10671937
• 负责人: MIKI Yoshiki
• 金额: $ 1.34万
• 依托单位: The University of Tokushima
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10671937/
• 关键词: OSTEOCYTES; DIFFERENTIATION; CALCIUM-SENSING RECEPTOR; RT-PCR ANALYSIS; IN SITU HYBRIDIZATION HISTOCHEMISTRY; EXTRACELLUIAR CALCIUM; CYTOSOLIC CALCIUM; ENDOPLASMIC RETICULUM; 細胞内情報伝達システム; オステカルシン; アルカリフォスファターゼ活性; 細胞内カルシウム; カルシウムチャンネル

Recently, a calcium-sensing receptor (CaSR) from bovine parathyroid tissue was cloned, and Northern blot analysis revealed expression of CaSR mRNA in several tissues other than the parathyroid gland. In the present study, we fractionated bone cells from 1-to 2-day-old rat calvaria by digestion with collagenase and EDTA and examined the expression of CaSR mRNA in cells of the various fractions by reverse transcription polymerase chain reaction (RT-PCR) analysis and in situ hybridization histochemistry. Fraction I cells had an elongate shape, and cells from fraction II through IV had a stellate and polygonal shape. Cells from fraction VI were small and stellate-shaped, and possessed a large number of long cytoplasmic processes. Fraction m cells expressed alkaline phosphatase (ALPase) activity and osteocalcin (Osc) mRNA, suggesting them to be osteoblasts. On the other hand, only fraction vl cells expressed CaSR mRNA ; and they displayed no ALPase activity or Osc mRNA. Furthermore, fraction VI cells responded to the elevated extracellular calcium with a rapid elevation of their cytosolic calcium. The phenomenon was independent of membrane voltage and insensitive to organic calcium channel modulators, such as BAY K 8644, nifedipine, and nicardipine. These findings strongly suggest that rat mature osteocytes express a CaSR that responds to elevated extracellular calcium.

最近，克隆了牛甲状旁腺组织的钙感应受体（CASR），北印迹分析显示，CASR mRNA在甲状旁腺以外的几个组织中的表达表达。在本研究中，我们通过用胶原酶和EDTA消化从1到2天大的大鼠颅钙化，并通过逆转录聚合酶链反应（RT-PCR）分析和原位杂交组织化学研究了各种分数细胞中CASR mRNA的表达。馏分I细胞具有细长形状，并且馏分II至IV的细胞具有星状和多边形形状。来自馏分VI的细胞小且呈星状形状，并具有大量长的细胞质过程。馏分M细胞表达碱性磷酸酶（ALPase）活性和骨钙素（OSC）mRNA，表明它们是成骨细胞。另一方面，只有分数VL细胞表达CASR mRNA。它们没有显示ALPase活性或OSC mRNA。此外，分数VI细胞对升高的细胞外钙有反应，其胞质钙迅速升高。该现象与膜电压无关，对有机钙通道调节剂不敏感，例如Bay K 8644，Nifedipine和Nicardipine。这些发现强烈表明，大鼠成熟的骨细胞表达了对升高细胞外钙反应的CASR。