The molecular nature of 1,25-(OH)2-D3-induced calcium-binding protein biosynthesis in the rat.
Exogenous 1,25-(OH)2-D3, administered to vitamin D-replete animals on a high calcium diet, induces biosynthesis of the duodenal, cytosolic calcium-binding protein (CaBP) in less than 2 h. This process can be blocked by simultaneously administered cycloheximide, but not by actinomycin D. In vitamin D-replete animals on a low Ca diet, on the other hand, 1,25-(OH)2-D3 administration leads to new CaBP synthesis only after about 7 h; this process can be blocked by actinomycin D. In vitamin D-deficient animals on a high calcium diet who have no CaBP, treatment with 1,25-(OH)2-D3 induces CaBP formation in congruent to 8 h; this process is known to be blocked by actinomycin D. Thus in D-replete animals on a low calcium diet and in D-deficient animals, CaBP biosynthesis proceeds by a transcriptional route, whereas in D-replete animals on a high calcium diet the rapid response appears to be posttranscriptional. This finding points to the possibility of a more rapid regulatory action of vitamin D than previously reported and how vitamin D might function in the D-replete state.
D000818:Animals; D002117:Calcitriol / Q000494:pharmacology*; D002135:Calcium-Binding Proteins / Q000096:biosynthesis*; D003609:Dactinomycin / Q000494:pharmacology; D007413:Intestinal Mucosa / Q000378:metabolism; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D014808:Vitamin D Deficiency / Q000378:metabolism
D002135:Calcium-Binding Proteins; D003609:Dactinomycin; D002117:Calcitriol