1,25-Dihydroxyvitamin D3 stimulates chondrogenesis of the chick limb bud mesenchymal cells.

Vitamin D has been known to be important for skeletal development and growth but the mechanism whereby it affects these processes is not well understood. We report now that the hormonal metabolite of vitamin D3, namely 1,25-dihydroxyvitamin D3, stimulates chondrogenesis in cultures of stage 24 chick embryo limb bud mesenchymal cells, as evidenced by morphologic changes as well as by increased transcription of collagen type II and core protein genes. This effect appears to be specific to 1,25(OH)2D3 since 24,25(OH)2D3 or D3 does not influence chondrogenesis in this system, and is probably mediated via the specific 1,25(OH)2D3 receptor protein which is undetectable in untreated cells but appears following exposure to the hormone.