Characterizing early events associated with the activation of target genes by 1,25-dihydroxyvitamin D3 in mouse kidney and intestine in vivo.
In this report, we explore the interaction of the vitamin D receptor (VDR) at regulatory sites within both the Cyp24a1 and the Trpv6 genes using chromatin immunoprecipitation techniques in a mouse model in vivo. We show that exogenous 1,25(OH)(2)D(3) induces rapid VDR and RXR (retinoid X receptor) binding to the Cyp24a1 gene in both the kidney and the intestine and to the Trpv6 gene in the intestine. Separate studies of Trpv6 in vitro suggest that VDR binding occurs directly to VDR response elements located -2 and -4 kb upstream of the TSS. VDR binding is dose-dependent, demonstrating EC(50) values that are comparable with those for the induction of both Cyp24a1 and Trpv6 mRNA. Importantly, interaction of the VDR with these targets results in rapid changes in histone 4 acetylation as well as the recruitment of RNA polymerase II. The presence of both VDR and RNA polymerase II at these sites declines between 3-6 h, whereas the changes observed in acetylation decrease more slowly. Finally, we show that whereas mediator protein 1 is recruited to the Cyp24a1 promoter in the intestine, this coactivator is apparently not required for Trpv6 activation. These studies provide the first evidence for 1,25(OH)(2)D(3)-induced VDR interaction at key target genes in vivo, revealing the consequences of that interaction on the Cyp24a1 and Trpv6 genes.
Meyer
Mark B
MB
Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706, USA.
Zella
Lee A
LA
Nerenz
Robert D
RD
Pike
J Wesley
JW
D000818:Animals; D002117:Calcitriol / Q000378:metabolism*; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation; D007413:Intestinal Mucosa / Q000378:metabolism*; D007668:Kidney / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D011401:Promoter Regions, Genetic; D012319:RNA Polymerase II / Q000378:metabolism; D018167:Receptors, Calcitriol / Q000378:metabolism; D047488:Retinoid X Receptors / Q000378:metabolism; D013250:Steroid Hydroxylases / Q000235:genetics; D013997:Time Factors; D065668:Vitamin D3 24-Hydroxylase
D018167:Receptors, Calcitriol; D047488:Retinoid X Receptors; D013250:Steroid Hydroxylases; C585550:Cyp24a1 protein, mouse; D065668:Vitamin D3 24-Hydroxylase; D012319:RNA Polymerase II; D002117:Calcitriol