1,25-Dihydroxyvitamin D3 effects on collagen and DNA synthesis in periosteum and periosteum-free calvaria.
1,25-dihydroxyvitamin D3 [1,25(OH)2D3] is essential for normal growth and mineralization, but its direct effects on various aspects of bone formation remain controversial. 1,25(OH)2D3 was studied for its effects on DNA, collagen and noncollagen protein synthesis, and alkaline phosphatase activity (APA) in the periosteum and periosteum-free bone from 21-day fetal rat calvariae. 1,25(OH)2D3 (0.01 to 10 nM) inhibited the incorporation of 3H-proline into collagenase-digestible protein (CDP) and the percent of collagen synthesized, and, at 10 nM, APA in the periosteum-free bone. 1,25(OH)2D3 inhibited type I collagen without affecting other collagen types. In contrast, 1,25(OH)2D3 at 10 nM caused a small but significant stimulation of the incorporation of 3H-thymidine into acid-insoluble residues (DNA) and on DNA content; both effects were exclusively observed in the periosteum. Hydroxyurea did not modify the inhibitory effect of 1,25(OH)2D3 on 3H-proline incorporation into CDP. These studies indicate that 1,25(OH)2D3 stimulates periosteal DNA synthesis but inhibits type I collagen synthesis and APA in the periosteum-free bone.
D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D001842:Bone and Bones / Q000187:drug effects / Q000378:metabolism*; D002117:Calcitriol / Q000494:pharmacology*; D003094:Collagen / Q000096:biosynthesis*; D004247:DNA / Q000096:biosynthesis*; D006918:Hydroxyurea / Q000494:pharmacology; D008940:Mitotic Index; D010521:Periosteum / Q000187:drug effects / Q000378:metabolism*; D011392:Proline / Q000378:metabolism; D051381:Rats
D003094:Collagen; D004247:DNA; D011392:Proline; D000469:Alkaline Phosphatase; D002117:Calcitriol; D006918:Hydroxyurea