1 alpha,25-dihydroxyvitamin D3 receptors and their action in embryonic chick chondrocytes.
The role of vitamin D in the maturation of epiphyseal chondrocytes was investigated in the developing chick embryo. Cartilage tissues were divided into two parts: resting cartilage and growth cartilage. A cytosol component to which 1 alpha,25-dihydroxyvitamin D3 (1 alpha,25(OH)2D3) is specifically bound first appeared in the growth cartilage on day 15, rapidly increased, and attained a maximum on day 19. The calcium content of the growth cartilage also began to increase on day 15 and continued to increase in parallel with the 1 alpha,25(OH)2D3 receptor levels. Glycosaminoglycan (GAG) synthesis by the growth cartilage cells increased from day 11-17 and rapidly declined thereafter reciprocally with the increase in calcium and receptor levels. In the resting cartilage, no cytosol receptor for 1 alpha,25(OH)2D3 was detected up to hatching time. The calcium content and GAG synthesis in the resting cartilage were very low and did not change appreciably throughout development. No receptor-like macromolecule for 24R,25-dihydroxyvitamin D3 (24R,25(OH)2D3) was recognized in either the resting or growth cartilage. 1 alpha,25(OH)2D3 added to the culture of chondrocytes from the epiphyseal growth cartilage inhibited GAG synthesis and stimulated its release from the cell layer into the medium in a dose-dependent manner. These in vitro effects of 1 alpha,25(OH)2D3 were not observed in chondrocytes obtained from 13-day-old growth cartilage and 19-day-old resting cartilage. 25-Hydroxyvitamin D3 and 24R,25(OH)2D3 had no effect on chondrocytes in any of the preparations. These results suggest that 1 alpha, 25 (OH)2D3 is directly involved in the maturation of chondrocytes and possibly in the calcification of growth cartilage.
Suda
S
S
Takahashi
N
N
Shinki
T
T
Horiuchi
N
N
Yamaguchi
A
A
Yoshiki
S
S
Enomoto
S
S
Suda
T
T
D000818:Animals; D002113:Calcification, Physiologic; D002117:Calcitriol / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D002642:Chick Embryo; D002762:Cholecalciferol / Q000378:metabolism / Q000494:pharmacology; D003600:Cytosol / Q000378:metabolism; D006025:Glycosaminoglycans / Q000378:metabolism; D006132:Growth Plate / Q000166:cytology / Q000196:embryology / Q000378:metabolism*; D018167:Receptors, Calcitriol; D011987:Receptors, Steroid / Q000378:metabolism*
D006025:Glycosaminoglycans; D018167:Receptors, Calcitriol; D011987:Receptors, Steroid; D002762:Cholecalciferol; D002117:Calcitriol; D002118:Calcium