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Conversion of vitamin D 3 to 1α,25‐dihydroxyvitamin D 3 in human skin equivalents
Author(s) -
Lehmann B.,
Rudolph T.,
Pietzsch J.,
Meurer M.
Publication year - 2000
Publication title -
experimental dermatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.108
H-Index - 96
eISSN - 1600-0625
pISSN - 0906-6705
DOI - 10.1034/j.1600-0625.2000.009002097.x
Subject(s) - vitamin d and neurology , calcitriol , hydroxylation , chemistry , vitamin , vitamin d binding protein , incubation , endocrinology , medicine , bovine serum albumin , enzyme , in vivo , biochemistry , biology , microbiology and biotechnology
These results demonstrate for the first time that human keratinocytes under in vivo ‐like conditions have the capacity of the enzymatic hydroxylation of vitamin D 3 to hormonally active calcitriol (1α,25(OH) 2 D 3 ). Supplementation of the culture medium with bovine serum albumin (BSA) up to 1.5% (w/v) amplifies the conversion of vitamin D 3 to 1α,25(OH) 2 D 3 . The maximum turnover rate of this reaction at 780 nM vitamin D 3 in presence of 1.0% (w/v) BSA amounts to approximately 3 pmol 1α,25(OH) 2 D 3 per 10 6 cells after 6 h of incubation. The hydroxylation of vitamin D 3 to 1α,25(OH) 2 D 3 is inhibited by the P‐450 oxidase inhibitor ketoconazole. The generation of 1α,25(OH) 2 D 3 from vitamin D 3 has an apparent Michaelis constant (K m ) of 2.3×10 −6 M. The intrinsic conversion of vitamin D 3 to biologically active 1α,25(OH) 2 D 3 may be of importance for the regulation of proliferation and differentiation of keratinocytes.