1,25-Dihydroxyvitamin D3 up-regulates the 1,25-dihydroxyvitamin D3 receptor in vivo.
The level of mRNA encoding the 1,25-dihydroxyvitamin D3 receptor in the intestine of vitamin D-deficient rats given 1,25-dihydroxyvitamin D3 was determined by Northern blot analysis using a 32P-labeled cDNA probe to the 1,25-dihydroxyvitamin D3 receptor. mRNA levels increased 10-fold above deficiency levels at 6 and 12 hr after an intravenous dose of 1,25-dihydroxyvitamin D3, returning to predosing levels at 24 hr. Total receptor protein level determined by an immunoradiometric assay was increased 2-fold at 12 hr. No change in unoccupied receptor levels determined by ligand-binding assay was observed during this period. These results suggest that 1,25-dihydroxyvitamin D3 increases receptor mRNA and total receptor level to maintain constant levels of unoccupied receptor.
Strom
M
M
Department of Biochemistry, University of Wisconsin Madison College of Agricultural and Life Sciences 53706.
Sandgren
M E
ME
Brown
T A
TA
DeLuca
H F
HF
D000818:Animals; D015152:Blotting, Northern; D002117:Calcitriol / Q000378:metabolism / Q000494:pharmacology*; D015342:DNA Probes; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000187:drug effects; D007700:Kinetics; D008297:Male; D012313:RNA / Q000235:genetics / Q000302:isolation & purification; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics*; D051381:Rats; D011919:Rats, Inbred Strains; D018167:Receptors, Calcitriol; D011987:Receptors, Steroid / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects*; D014808:Vitamin D Deficiency / Q000235:genetics / Q000378:metabolism*
D015342:DNA Probes; D012333:RNA, Messenger; D018167:Receptors, Calcitriol; D011987:Receptors, Steroid; D012313:RNA; D002117:Calcitriol