title: Transcriptional and post-transcriptional regulation of vitamin D-dependent calcium-binding protein gene expression in the rat duodenum by 1,25-dihydroxycholecalciferol.
abstract: Regulation of the expression of vitamin D-dependent calcium-binding protein (Mr 9000 CaBP) gene by 1,25-dihydroxycholecalciferol (1,25-(OH)2D3) was studied in the rat duodenum. In vivo stimulation of Mr 9000 CaBP synthesis was analyzed using a complementary DNA probe and by measuring the rate of Mr 9000 CaBP gene transcription in isolated nuclei (run-on assay). A single 1,25-(OH)2D3 injection (650 pmol/100 g of body weight) induced a 2-fold increase in Mr 9000 CaBP gene transcription within 15 min in the duodenum of vitamin D-deficient rats. RNA synthesis was maximal at 1 h, then decreased until 16 h of postinjection. There was an initial transient accumulation of Mr 9000 CaBP mRNA (from 7 to 15 min), which was followed by a second, significant increase, by 3 h which remained elevated until 16 h. The magnitude and time course of the Mr 9000 CaBP increase was similar to that of its mRNA as early as 1 h after 1,25-(OH)2D3 administration. Mr 9000 CaBP gene transcription was not significantly induced by 1,25-(OH)2D3 in vitamin D-replete rats and no transient accumulation of Mr 9000 CaBP mRNA was observed. Thus, 1,25-(OH)2D3 modulates Mr 9000 CaBP gene expression in at least two ways, a rapid transcriptional stimulation and a post-transcriptional effect preventing degradation of Mr 9000 CaBP transcripts and accounting for their accumulation several hours after the hormone treatment.
mesh_terms: D000818:Animals; D002117:Calcitriol / Q000494:pharmacology*; D004247:DNA / Q000032:analysis; D004386:Duodenum / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects*; D007413:Intestinal Mucosa / Q000378:metabolism; D008297:Male; D008970:Molecular Weight; D011499:Protein Processing, Post-Translational; D012313:RNA / Q000096:biosynthesis; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D064030:S100 Calcium Binding Protein G / Q000235:genetics*; D014158:Transcription, Genetic
chemical_list: D012333:RNA, Messenger; D064030:S100 Calcium Binding Protein G; D012313:RNA; D004247:DNA; D002117:Calcitriol