Kanatani M, Sugimoto T, Kanzawa M, Yano S, Chihara K
Department of Medicine, Kobe University School of Medicine, Kobe, Japan.
Biochem Biophys Res Commun. 1999 Jul 22;261(1):144-8. doi: 10.1006/bbrc.1999.0932.
Although it has recently been suggested that high extracellular calcium (Ca(2+)) inhibits osteoclast function via a calcium-sensing receptor (CaSR) in mature osteoclasts, the role of CaSR in the regulation of osteoclast formation remains unknown. The present study was performed to investigate whether osteoclast precursor cells possess CaSR and to clarify the possible role of CaSR in the regulation of osteoclast formation. Immunocytochemistry detected CaSR in osteoclast precursor cells derived from spleen cells as well as in osteoblastic MC3T3-E1 cells. The use of reverse-transcription polymerase chain reaction (RT-PCR) with CaSR-specific primers, followed by nucleotide sequencing of the amplified products, also identified CaSR transcripts in osteoclast precursor cells derived from spleen cells as well as in MC3T3-E1 cells. High Ca(2+) (3 to 5 mM) concentration dependently inhibited 1,25(OH)2D3- or human parathyroid hormone (hPTH) (1-34)-induced osteoclast-like cell (Ocl) formation from osteoclast precursor cells derived from spleen cells. Further, the CaSR agonist neomycin also concentration dependently inhibited 1,25(OH)2D3- or hPTH(1-34)-induced Ocl formation. Moreover, a calcimimetic which mimics or potentiates the effects of Ca(2+) at the CaSR NPS R-467 (1-100 microM) concentration dependently inhibited Ocl formation stimulated by 1,25(OH)2D3 or hPTH(1-34). These findings first demonstrated that osteoclast precursor cells possess CaSR very similar, if not identical, to those in the parathyroid and kidney. Furthermore, the CaSR in osteoclast precursor cells could play a key role in regulating Ocl formation by sensing local changes in Ca(2+) at the resorptive sites.
尽管最近有研究表明，高细胞外钙浓度（Ca(2+)）可通过成熟破骨细胞中的钙敏感受体（CaSR）抑制破骨细胞功能，但CaSR在破骨细胞形成调节中的作用仍不清楚。本研究旨在探讨破骨细胞前体细胞是否表达CaSR，并阐明CaSR在破骨细胞形成调节中的可能作用。免疫细胞化学检测发现，源自脾细胞的破骨细胞前体细胞以及成骨细胞MC3T3-E1细胞中均有CaSR表达。使用CaSR特异性引物进行逆转录聚合酶链反应（RT-PCR），并对扩增产物进行核苷酸测序，也证实源自脾细胞的破骨细胞前体细胞以及MC3T3-E1细胞中均有CaSR转录本。高Ca(2+)浓度（3至5 mM）可浓度依赖性抑制源自脾细胞的破骨细胞前体细胞在1,25(OH)2D3或人甲状旁腺激素（hPTH）（1-34）诱导下形成破骨细胞样细胞（Ocl）。此外，CaSR激动剂新霉素也可浓度依赖性抑制1,25(OH)2D3或hPTH(1-34)诱导的Ocl形成。此外，一种模拟或增强Ca(2+)在CaSR作用的钙敏感受体激动剂NPS R-467（1-100 microM）可浓度依赖性抑制1,25(OH)2D3或hPTH(1-34)刺激的Ocl形成。这些发现首次表明，破骨细胞前体细胞拥有与甲状旁腺和肾脏中非常相似（即便不完全相同）的CaSR。此外，破骨细胞前体细胞中的CaSR可能通过感知吸收部位Ca(2+)的局部变化，在调节Ocl形成中发挥关键作用。
