Sato Yuiko, Miyauchi Yoshiteru, Yoshida Shigeyuki, Morita Mayu, Kobayashi Tami, Kanagawa Hiroya, Katsuyama Eri, Fujie Atsuhiro, Hao Wu, Tando Toshimi, Watanabe Ryuichi, Miyamoto Kana, Morioka Hideo, Matsumoto Morio, Toyama Yoshiaki, Miyamoto Takeshi
Department of Orthopedic Surgery, Keio University School of Medicine, Shinjuku-ku, Tokyo, Japan; Department of Musculoskeletal Reconstruction and Regeneration Surgery, Keio University School of Medicine, Shinjuku-ku, Tokyo, Japan.
Department of Orthopedic Surgery, Keio University School of Medicine, Shinjuku-ku, Tokyo, Japan.
PLoS One. 2014 Nov 6;9(11):e111845. doi: 10.1371/journal.pone.0111845. eCollection 2014.
Although both an active form of the vitamin D metabolite, 1,25(OH)2D3, and the vitamin D analogue, ED71 have been used to treat osteoporosis, anti-bone resorbing activity is reportedly seen only in ED71- but not in 1,25(OH)2D3 -treated patients. In addition, how ED71 inhibits osteoclast activity in patients has not been fully characterized. Recently, HIF1α expression in osteoclasts was demonstrated to be required for development of post-menopausal osteoporosis. Here we show that ED71 but not 1,25(OH)2D3, suppress HIF1α protein expression in osteoclasts in vitro. We found that 1,25(OH)2D3 or ED71 function in osteoclasts requires the vitamin D receptor (VDR). ED71 was significantly less effective in inhibiting M-CSF and RANKL-stimulated osteoclastogenesis than was 1,25(OH)2D3 in vitro. Downregulation of c-Fos protein and induction of Ifnβ mRNA in osteoclasts, both of which reportedly block osteoclastogenesis induced by 1,25(OH)2D3 in vitro, were both significantly higher following treatment with 1,25(OH)2D3 than with ED71. Thus, suppression of HIF1α protein activity in osteoclasts in vitro, which is more efficiently achieved by ED71 rather than by 1,25(OH)2D3, could be a reliable read-out in either developing or screening reagents targeting osteoporosis.
尽管维生素D代谢物的活性形式1,25(OH)2D3和维生素D类似物ED71都已用于治疗骨质疏松症，但据报道，只有接受ED71治疗的患者出现了抗骨吸收活性，而接受1,25(OH)2D3治疗的患者则未出现。此外，ED71在患者体内抑制破骨细胞活性的方式尚未完全明确。最近，有研究表明，破骨细胞中的HIF1α表达是绝经后骨质疏松症发生发展所必需的。在此我们表明，ED71而非1,25(OH)2D3，可在体外抑制破骨细胞中HIF1α蛋白的表达。我们发现，1,25(OH)2D3或ED71在破骨细胞中的功能需要维生素D受体（VDR）。在体外，ED71抑制M-CSF和RANKL刺激的破骨细胞生成的效果明显低于1,25(OH)2D3。破骨细胞中c-Fos蛋白的下调和Ifnβ mRNA的诱导，据报道这两者在体外均可阻断1,25(OH)2D3诱导的破骨细胞生成，在用1,25(OH)2D3治疗后均显著高于用ED71治疗。因此，在体外破骨细胞中抑制HIF1α蛋白活性（ED71比1,25(OH)2D3能更有效地实现这一点），可能是开发或筛选针对骨质疏松症的试剂的可靠指标。
