1 alpha, 25-Dihydroxyvitamin D3 and analogues of vitamin D3 induce alkaline phosphatase activity in osteoblastic cells derived from newborn mouse calvaria.
In order to study the effects of vitamin D metabolites on bone metabolism, clone MC3T3-E1 cells, which have retained osteoblastic activity, were cultured with various concentrations of the hormone, 1 alpha, 25-dihydroxyvitamin D3 [1 alpha, 25 (OH)2D3]. A physiological concentration of 1 alpha, 25 (OH)2D3 stimulated alkaline phosphatase (ALP) activity in the cells. Other metabolites--1 alpha, 24-dihydroxyvitamin D3 [1 alpha, 24 (OH)2D3], 1 alpha-hydroxyvitamin D3 [1 alpha (OH)D3], and 24R,25-dihydroxyvitamin D3 [24R,25 (OH)2D3]--also induced increases in ALP activity in a dose-dependent fashion. However, their effective concentrations were 100 or 1,000 times greater than that of 1 alpha, 25 (OH)2D3. Hormone-induced and native ALP activities in the cells were of the same type as that found in newborn mouse calvaria; that is, they were heat-labile, L-homoarginine- and levamisole-sensitive, and L-phenylalanine-insensitive (liver-bone-kidney type). These results show that vitamin D metabolites stimulate bone formation in vitro and that they may be involved in bone formation in vivo as well.
D000469:Alkaline Phosphatase / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D001842:Bone and Bones / Q000201:enzymology; D002117:Calcitriol / Q000494:pharmacology*; D002460:Cell Line; D002762:Cholecalciferol / Q000494:pharmacology*; D002999:Clone Cells; D004790:Enzyme Induction; D007700:Kinetics; D051379:Mice; D010006:Osteoblasts / Q000187:drug effects / Q000201:enzymology*
D002762:Cholecalciferol; D000469:Alkaline Phosphatase; D002117:Calcitriol