J. Biol. Chem., Vol. 265, Issue 17, 10025-10029, 06, 1990
Phosphorylation of the 1,25-dihydroxyvitamin D3 receptor. A primary event in 1,25-dihydroxyvitamin D3 action
TA Brown and HF DeLuca
Department of Biochemistry, University of Wisconsin, College of Agricultural and Life Sciences, Madison 53706.
1,25-Dihydroxyvitamin D3 is believed to mediate the regulation of calcium
metabolism by a steroid hormone receptor mechanism. We now demonstrate that
phosphorylation of the 1,25-dihydroxyvitamin D3 receptor occurs rapidly in
embryonic chick duodenal organ culture in response to 1,25-dihydroxyvitamin
D3. Phosphorylation of the receptor is strongly induced within 1 h by
1,25-dihydroxyvitamin D3 and occurs prior to the initiation of calcium
uptake or induction of calcium- binding protein in this system.
Phosphorylation is not affected by inhibition of protein synthesis by
cycloheximide. Since chick duodenal organ culture is a vitamin D-responsive
system that closely parallels in vivo rachitic chicken intestine, the
occurrence of receptor phosphorylation in response to 1,25-dihydroxyvitamin
D3 strongly suggests that it is a physiologically relevant event. In
addition, since it occurs prior to the other responses to
1,25-dihydroxyvitamin D3, it appears possible that phosphorylation may play
a significant role in the 1,25-dihydroxyvitamin D3 regulation of
transcription in the intestine.