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Rapid publication: Constitutive expression of a vitamin D 1‐hydroxylase in a myelomonocytic cell line: A model for studying 1,25‐dihydroxyvitamin D production in vitro
Author(s) -
Adams John S.,
Beeker Timothy G.,
Hongo Takashi,
Clemens Thomas L.
Publication year - 1990
Publication title -
journal of bone and mineral research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.882
H-Index - 241
eISSN - 1523-4681
pISSN - 0884-0431
DOI - 10.1002/jbmr.5650051212
Subject(s) - metabolite , cell culture , calcitriol , vitamin d and neurology , chemistry , cholecalciferol , stereochemistry , medicine , endocrinology , biochemistry , biology , genetics
The capacity of the v‐ myc ‐transformed, chicken myelomonocytic cell line HD‐11 to metabolize 25‐hydroxyvitamin D 3 (25‐OHD 3 ) was examined. HD‐11 cells produced and secreted a metabolite of 25‐OHD, that was bound with high affinity by receptor for 1,25‐dihydroxyvitamin D 3 [1,25‐(OH) 2 D 3 ]. On normal‐phase HPLC, this metabolite cochromatographed with authentic 1,25‐(OH) 2 D 3 in both hexane‐ and methylene chloride‐based solvent systems. The 25‐OHD, 1‐hydroxylation reaction was substrate saturable with a K m of 73 nM 25‐OHD 3 and a maximal velocity of 167 fmol per 10 6 cells per h. This reaction was inhibited by keto‐conazole, a recognized inhibitor of cytochrome P 450 mixed‐function oxidases including the authentic, renal 25‐OHD3 1‐hydroxylase. On the other hand, HD‐11 cell 1,25‐(OH) 2 D 3 production was not affected by the antioxidant DPPD, a known inhibitor of free radical‐generated 1,25‐(OH) 2 D 3 . In addition to synthesizing 1,25‐(OH) 2 D 3 , this monocyte‐macrophage cell line also has the potential to be a target for the hormone; HD‐11 cells express high‐affinity receptor for 1,25‐(OH) 2 D 3 ( K in = 0.06 nM). Division of Endocrinology and Metabolism, Cedars‐Sinai Medical Center‐UCLA School of Medicine, Los Angeles, CA 90048.