PMID- 28602960 OWN - NLM STAT- MEDLINE DCOM- 20190312 LR - 20191210 IS - 1879-1220 (Electronic) IS - 0960-0760 (Print) IS - 0960-0760 (Linking) VI - 177 DP - 2018 Mar TI - The impact of VDR expression and regulation in vivo. PG - 36-45 LID - S0960-0760(17)30153-X [pii] LID - 10.1016/j.jsbmb.2017.06.002 [doi] AB - The vitamin D receptor (VDR) mediates the pleiotropic biological actions of 1,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)). These actions include orchestration of mineral homeostasis which is coordinated by the kidney, intestine, bone and parathyroid gland wherein the VDR transcriptionally regulates expression of the genes involved in this complex process. Mutations in human VDR (hVDR) cause hereditary vitamin D resistant rickets, a genetic syndrome characterized by hypocalcemia, hyperparathyroidism and rickets resulting from dysregulation of mineral homeostasis. Expression of the VDR is regulated by external stimuli in a tissue-specific manner. However, the mechanisms of this tissue-specificity remain unclear. Studies also suggest that phosphorylation of hVDR at serine 208 impacts the receptor's transcriptional activity. These experiments were conducted in vitro, however, and therefore limited in their conclusions. In this report, we summarize (1) our most recently updated ChIP-seq data from mouse tissues to identify regulatory regions responsible for the tissues-specific regulation of the VDR and (2) our studies to understand the mechanism of hormonal regulation of Vdr expression in bone and kidney in vivo using transgenic mouse strains generated by mouse mini-genes that contain comprehensive genetic information capable of recapitulating endogenous Vdr gene regulation and expression. We also defined the functional human VDR gene locus in vivo by using a human mini-gene comparable to that in the mouse to generate a humanized VDR mouse strain in which the receptor is expressed at normal levels (normal expressor). The present report also shows that a humanized mouse model in which the VDR is expressed at levels about 10-fold lower than the normal expressor mouse rescued the VDR-null phenotype despite its reduced transcriptional activity relative to wildtype expression. We also generated an additional humanized mouse model expressing hVDR bearing a mutation converting serine 208 to alanine (hVDR-S208A). In spite of the mutation, target gene expression induced by the ligand was unchanged relative to a mouse strain expressing comparable levels of wildtype hVDR. Further characterization also showed that serum calcium and parathyroid hormone levels were normal and alopecia was not observed in this hVDR-S208A mouse strain as well. Taken together, our in vivo studies using ChIP-seq analyses and the mini-gene transgenic mice improve our understanding of the tissue-specific regulatory mechanisms of controlling VDR expression and the mechanisms of action of the VDR. CI - Copyright (c) 2017 Elsevier Ltd. All rights reserved. FAU - Lee, Seong Min AU - Lee SM AD - Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, United States. FAU - Meyer, Mark B AU - Meyer MB AD - Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, United States. FAU - Benkusky, Nancy A AU - Benkusky NA AD - Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, United States. FAU - O'Brien, Charles A AU - O'Brien CA AD - University of Arkansas for Medical Sciences, Little Rock, AR 72205, United States. FAU - Pike, J Wesley AU - Pike JW AD - Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, United States. Electronic address: pike@biochem.wisc.edu. LA - eng GR - R01 AR045173/AR/NIAMS NIH HHS/United States GR - R01 AR064424/AR/NIAMS NIH HHS/United States GR - R01 DK072281/DK/NIDDK NIH HHS/United States GR - R01 DK073995/DK/NIDDK NIH HHS/United States PT - Journal Article PT - Research Support, N.I.H., Extramural DEP - 20170609 PL - England TA - J Steroid Biochem Mol Biol JT - The Journal of steroid biochemistry and molecular biology JID - 9015483 RN - 0 (Receptors, Calcitriol) RN - EC 1.14.15.18 (25-Hydroxyvitamin D3 1-alpha-Hydroxylase) SB - IM MH - 25-Hydroxyvitamin D3 1-alpha-Hydroxylase/genetics MH - Animals MH - Bone and Bones/metabolism MH - Cell Line MH - Female MH - Gene Expression MH - Humans MH - Intestines/physiology MH - Kidney/metabolism MH - Male MH - Mice, Transgenic MH - Receptors, Calcitriol/*genetics/*metabolism PMC - PMC5723236 MID - NIHMS886448 OTO - NOTNLM OT - 1,25-dihydroxyvitamin D(3) OT - Bacterial artificial chromosome OT - ChIP-seq OT - Hereditary vitamin D resistant rickets OT - Humanized VDR mouse model OT - Vitamin D receptor COIS- Conflict of interest The authors have no conflict of interest to declare. EDAT- 2017/06/13 06:00 MHDA- 2019/03/13 06:00 PMCR- 2019/03/01 CRDT- 2017/06/13 06:00 PHST- 2017/05/04 00:00 [received] PHST- 2017/06/02 00:00 [revised] PHST- 2017/06/05 00:00 [accepted] PHST- 2017/06/13 06:00 [pubmed] PHST- 2019/03/13 06:00 [medline] PHST- 2017/06/13 06:00 [entrez] PHST- 2019/03/01 00:00 [pmc-release] AID - S0960-0760(17)30153-X [pii] AID - 10.1016/j.jsbmb.2017.06.002 [doi] PST - ppublish SO - J Steroid Biochem Mol Biol. 2018 Mar;177:36-45. doi: 10.1016/j.jsbmb.2017.06.002. Epub 2017 Jun 9.