title: 1,25-Dihydroxyvitamin D3 increases synthesis of the vitamin K-dependent bone protein by osteosarcoma cells.
abstract: Rat osteosarcoma cells respond to 1,25-dihydroxyvitamin D3 with a 6-fold increase in intracellular and secreted levels of the vitamin K-dependent protein of bone (BGP). The rise in intracellular BGP levels is half-maximal at 6.6 h and precedes the rise in medium BGP levels by 6 h, a time course which is consistent with the postulated steroid hormone action of 1,25-dihydroxyvitamin D3. This effect is achieved by physiological levels of 1,25-dihydroxyvitamin D3, with half of the maximal response at a vitamin concentration of 0.04 ng/ml. The specificity of this effect for BGP is demonstrated by the absence of a 1,25-dihydroxyvitamin D3 effect on total protein synthesis by these cells. To our knowledge, BGP is the first example of a bone protein whose rate of synthesis is dramatically and specifically increased by physiological levels of 1,25-dihydroxyvitamin D3. The possible functions of BGP in the biological actions of 1,25-dihydroxyvitamin D3 on bone are discussed.
mesh_terms: D015055:1-Carboxyglutamic Acid; D000818:Animals; D001842:Bone and Bones; D002117:Calcitriol; D002460:Cell Line; D004100:Dihydroxycholecalciferols / Q000494:pharmacology*; D005971:Glutamates; D006887:Hydroxycholecalciferols / Q000494:pharmacology*; D007700:Kinetics; D009374:Neoplasms, Experimental / Q000378:metabolism; D015675:Osteocalcin; D012516:Osteosarcoma / Q000378:metabolism*; D014176:Protein Biosynthesis; D051381:Rats; D014812:Vitamin K / Q000494:pharmacology*
chemical_list: D004100:Dihydroxycholecalciferols; D005971:Glutamates; D006887:Hydroxycholecalciferols; D015675:Osteocalcin; D014812:Vitamin K; D015055:1-Carboxyglutamic Acid; D002117:Calcitriol