Role of vitamin D in bone resorption

✍ Scribed by Tatsuo Suda; Naoyuki Takahashi; Etsuko Abe

• Publisher: John Wiley and Sons
• Year: 1992
• Tongue: English
• Weight: 604 KB
• Volume: 49
• Category: Article
• ISSN: 0730-2312
• DOI: 10.1002/jcb.240490110

✦ Synopsis

The idea that vitamin D must function at the bone site to promote bone mineralization has long existed since its discovery as an anti-rachitic agent. However, the definite evidence for this is still lacking. In contrast, much evidence has accumulated that 1 c ~, 2 5 ( 0 H ) ~D ~ is involved in bone resorption. 1 ~Y , ~~( O H ) ~D ~ tightly regulates differentiation of osteoclast progenitors into osteoclasts. Osteoclast progenitors have been thought to belong to the monocytemacrophage lineage. 1 c ~, 2 5 ( 0 H ) ~D ~ greatly stimulates differentiation and activation of mononuclear phagocytes. Recent reports have indicated that differentiation of mononuclear phagocytes into osteoclasts is strictly regulated by osteoblastic cells, the process of which is also stimulated by 1 c ~, 2 5 ( 0 H ) ~D ~.

In the differentiation of mononuclear phagocytes into osteoclasts, the target cells for 1 C X , ~~( O H ) ~D ~ appear to be osteoblastic stromal cells. Osteoblastic cells produce several proteins such as BGP, MGP, osteopontin and the third component of complement ( C 3 ) in response to the vitamin. They appear to be somehow involved in osteoclast differentiation and functions. Thus, 1 ~Y , ~~( O H ) ~D ~ seems to be involved in the differentiation of osteoclast progenitors into osteoclasts directly and also by an indirect mechanism involving osteoblastic cells. The precise role of osteoblastic cells in osteoclast development has to be elucidated in the future. o 1992 WiIey-Liss, ~n c .