Document Detail

Human bone cells in culture metabolize 25-hydroxyvitamin D3 to 1,25-dihydroxyvitamin D3 and 24,25-dihydroxyvitamin D3.
MedLine Citation:
PMID:  6973569     Owner:  NLM     Status:  MEDLINE    
Bone cells respond to 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) for mineral mobilization and contain receptors for 1,25(OH)2D3. We report here the expression of 25-hydroxyvitamin D3 (25 (OH)D3) metabolizing enzymes in primary cultures of human bone cells, as well as n a human osteosarcoma cell line. Human bone cells were obtained by enzyme digestion of the extracellular matrix of bone from iliac crest biopsies from 3 male patients without primary bone disease. These cells were plated (5 X 10(4)/min) in medium with 10% fetal calf serum and proliferated to confluence in 10-14 days. At confluence, the medium was replaced with serum-free medium. The cells were preincubated in this serum-free medium for 24 h prior to incubating them 2-4 h with [3H]25(OH)D3 (10-20 nM). The vitamin D metabolites synthesized during this incubation were extracted from the medium and cells with dichloromethane, then separated by chromatography on Sephadex LH-20, followed by high performance liquid chromatography. The cells synthesized 1,25(OH)2D3 and 24,25-dihydroxyvitamin D3 (24,25(OH)2D3) with the specific activities of the 1- and 24-hydroxylases similar in magnitude to those in kidney cells in vitro. The enzymes could be regulated by external perturbations, in that the activity of the 1-hydroxylase was inhibited by preincubation of the cells for 8 h with 1,25(OH)2D3 (10 nM), whereas the 24-hydroxylase was enhanced. Incubation of the cells in a low calcium medium (0.6 mM) depressed the 24-hydroxylase activity. We conclude: 1) normal human bone cells can produce 1,25(OH)2D3 and 24,25(OH)2D3 in vitro in amounts similar to kidney cells, suggesting a physiological significance and 2) this synthesis could account for the increase in osteoclast number in anephric patients with renal osteodystrophy.
G A Howard; R T Turner; D J Sherrard; D J Baylink
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The Journal of biological chemistry     Volume:  256     ISSN:  0021-9258     ISO Abbreviation:  J. Biol. Chem.     Publication Date:  1981 Aug 
Date Detail:
Created Date:  1981-10-14     Completed Date:  1981-10-14     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  2985121R     Medline TA:  J Biol Chem     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  7738-40     Citation Subset:  IM    
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MeSH Terms
24,25-Dihydroxyvitamin D 3
Bone and Bones / metabolism*
Cells, Cultured
Chromatography, High Pressure Liquid
Dihydroxycholecalciferols / biosynthesis*
Hydroxycholecalciferols / biosynthesis*,  metabolism*
Grant Support
Reg. No./Substance:
0/Dihydroxycholecalciferols; 0/Hydroxycholecalciferols; 19356-17-3/Calcifediol; 32222-06-3/Calcitriol; 40013-87-4/24,25-Dihydroxyvitamin D 3

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