[Frontiers in vitamin D; basic research and clinical application. Is VDR a factor of bone volume regulator in bone tissues?]

Vitamin D is one of the best established hormone to exert beneficial action for bone mass control and bone metabolism. Such vitamin D action for bone tissue is recapitulated in intact animals, while vitamin D is well known to potentiate bone resorption by inducing gene of RANKL an osteoclastic inducer. By genetic characterization of VDR in mice, VDR was found to serve as a negative regulator in intact bone. Moreover, RANKL gene expression level in intact bone was down-regulated in osteoblast-specific VDR KO mice. Thus, these findings indicate that VDR in bone tissue is a negative regulator for bone mass control.