Conversion of vitamin D3 to 1α,25‐dihydroxyvitamin D3 in human skin equivalents
- 1 April 2000
- journal article
- research article
- Published by Wiley in Experimental Dermatology
- Vol. 9 (2) , 97-103
- https://doi.org/10.1034/j.1600-0625.2000.009002097.x
Abstract
These results demonstrate for the first time that human keratinocytes under in vivo‐like conditions have the capacity of the enzymatic hydroxylation of vitamin D3 to hormonally active calcitriol (1α,25(OH)2D3). Supplementation of the culture medium with bovine serum albumin (BSA) up to 1.5% (w/v) amplifies the conversion of vitamin D3 to 1α,25(OH)2D3. The maximum turnover rate of this reaction at 780 nM vitamin D3 in presence of 1.0% (w/v) BSA amounts to approximately 3 pmol 1α,25(OH)2D3 per 106 cells after 6 h of incubation. The hydroxylation of vitamin D3 to 1α,25(OH)2D3 is inhibited by the P‐450 oxidase inhibitor ketoconazole. The generation of 1α,25(OH)2D3 from vitamin D3 has an apparent Michaelis constant (Km) of 2.3×10−6 M. The intrinsic conversion of vitamin D3 to biologically active 1α,25(OH)2D3 may be of importance for the regulation of proliferation and differentiation of keratinocytes.Keywords
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