Vitamin D receptor signaling and its therapeutic implications: Genome-wide and structural view

2015 ◽  
Vol 93 (5) ◽  
pp. 311-318 ◽  
Author(s):  
Carsten Carlberg ◽  
Ferdinand Molnár

Vitamin D3 is one of the few natural compounds that has, via its metabolite 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3) and the transcription factor vitamin D receptor (VDR), a direct effect on gene regulation. For efficiently applying the therapeutic and disease-preventing potential of 1,25(OH)2D3 and its synthetic analogs, the key steps in vitamin D signaling need to be understood. These are the different types of molecular interactions with the VDR, such as (i) the complex formation of VDR with genomic DNA, (ii) the interaction of VDR with its partner transcription factors, (iii) the binding of 1,25(OH)2D3 or its synthetic analogs within the ligand-binding pocket of the VDR, and (iv) the resulting conformational change on the surface of the VDR leading to a change of the protein–protein interaction profile of the receptor with other proteins. This review will present the latest genome-wide insight into vitamin D signaling, and will discuss its therapeutic implications.

2020 ◽  
Vol 64 (4) ◽  
pp. R45-R56 ◽  
Author(s):  
Andrea Hanel ◽  
Henna-Riikka Malmberg ◽  
Carsten Carlberg

Molecular endocrinology of vitamin D is based on the activation of the transcription factor vitamin D receptor (VDR) by the vitamin D metabolite 1α,25-dihydroxyvitamin D3. This nuclear vitamin D-sensing process causes epigenome-wide effects, such as changes in chromatin accessibility as well as in the contact of VDR and its supporting pioneer factors with thousands of genomic binding sites, referred to as vitamin D response elements. VDR binding enhancer regions loop to transcription start sites of hundreds of vitamin D target genes resulting in changes of their expression. Thus, vitamin D signaling is based on epigenome- and transcriptome-wide shifts in VDR-expressing tissues. Monocytes are the most responsive cell type of the immune system and serve as a paradigm for uncovering the chromatin model of vitamin D signaling. In this review, an alternative approach for selecting vitamin D target genes is presented, which are most relevant for understanding the impact of vitamin D endocrinology on innate immunity. Different scenarios of the regulation of primary upregulated vitamin D target genes are presented, in which vitamin D-driven super-enhancers comprise a cluster of persistent (constant) and/or inducible (transient) VDR-binding sites. In conclusion, the spatio-temporal VDR binding in the context of chromatin is most critical for the regulation of vitamin D target genes.


2016 ◽  
Vol 37 (5) ◽  
pp. 521-547 ◽  
Author(s):  
Peter J. Tebben ◽  
Ravinder J. Singh ◽  
Rajiv Kumar

AbstractHypercalcemia occurs in up to 4% of the population in association with malignancy, primary hyperparathyroidism, ingestion of excessive calcium and/or vitamin D, ectopic production of 1,25-dihydroxyvitamin D [1,25(OH)2D], and impaired degradation of 1,25(OH)2D. The ingestion of excessive amounts of vitamin D3 (or vitamin D2) results in hypercalcemia and hypercalciuria due to the formation of supraphysiological amounts of 25-hydroxyvitamin D [25(OH)D] that bind to the vitamin D receptor, albeit with lower affinity than the active form of the vitamin, 1,25(OH)2D, and the formation of 5,6-trans 25(OH)D, which binds to the vitamin D receptor more tightly than 25(OH)D. In patients with granulomatous disease such as sarcoidosis or tuberculosis and tumors such as lymphomas, hypercalcemia occurs as a result of the activity of ectopic 25(OH)D-1-hydroxylase (CYP27B1) expressed in macrophages or tumor cells and the formation of excessive amounts of 1,25(OH)2D. Recent work has identified a novel cause of non-PTH-mediated hypercalcemia that occurs when the degradation of 1,25(OH)2D is impaired as a result of mutations of the 1,25(OH)2D-24-hydroxylase cytochrome P450 (CYP24A1). Patients with biallelic and, in some instances, monoallelic mutations of the CYP24A1 gene have elevated serum calcium concentrations associated with elevated serum 1,25(OH)2D, suppressed PTH concentrations, hypercalciuria, nephrocalcinosis, nephrolithiasis, and on occasion, reduced bone density. Of interest, first-time calcium renal stone formers have elevated 1,25(OH)2D and evidence of impaired 24-hydroxylase-mediated 1,25(OH)2D degradation. We will describe the biochemical processes associated with the synthesis and degradation of various vitamin D metabolites, the clinical features of the vitamin D-mediated hypercalcemia, their biochemical diagnosis, and treatment.


2008 ◽  
Vol 198 (2) ◽  
pp. 261-269 ◽  
Author(s):  
Rene F Chun ◽  
John S Adams ◽  
Martin Hewison

Our perception of the vitamin D system continues to evolve. Recent studies have re-evaluated the parameters for adequate vitamin D status in humans, revealing a high prevalence of insufficiency in many populations throughout the world. Other reports have highlighted the potential consequences of vitamin D insufficiency beyond established effects on bone homeostasis. Most notably, there is now strong evidence of a role for vitamin D in modulating innate and adaptive immunities, with insufficiency being linked to infectious disease and other immune disorders. To date, signaling pathways for these new responses to vitamin D have been based on established endocrine models for active 1,25-dihydroxyvitamin D, despite present evidence for more localized, intracrine modes of action. In the following review, we provide a fresh perspective on vitamin D signaling in non-classical target cells such as macrophages by highlighting novel factors associated with the transport and action of this pluripotent secosteroid.


2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
James P. Whitcomb ◽  
Mary DeAgostino ◽  
Mark Ballentine ◽  
Jun Fu ◽  
Martin Tenniswood ◽  
...  

Vitamin D signaling modulates a variety of immune responses. Here, we assessed the role of vitamin D in immunity to experimental leishmaniasis infection in vitamin D receptor-deficient mice (VDRKO). We observed that VDRKO mice on a genetically resistant background have decreasedLeishmania major-induced lesion development compared to wild-type (WT) mice; additionally, parasite loads in infected dermis were significantly lower at the height of infection. Enzymatic depletion of the active form of vitamin D mimics the ablation of VDR resulting in an increased resistance toL. major. Conversely, VDRKO or vitamin D-deficient mice on the susceptible Th2-biased background had no change in susceptibility. These studies indicate vitamin D deficiency, either through the ablation of VDR or elimination of its ligand, 1,25D3, leads to an increase resistance toL. majorinfection but only in a host that is predisposed for Th-1 immune responses.


2014 ◽  
Vol 111 (1) ◽  
pp. 33-40 ◽  
Author(s):  
Peter J. Malloy ◽  
Velibor Tasic ◽  
Doris Taha ◽  
Filiz Tütüncüler ◽  
Goh Siok Ying ◽  
...  

2013 ◽  
Vol 19 (8) ◽  
pp. 1035-1045 ◽  
Author(s):  
Jun-ichi Satoh ◽  
Hiroko Tabunoki

Background: Vitamin D is a liposoluble vitamin essential for calcium metabolism. The ligand-bound vitamin D receptor (VDR), heterodimerized with retinoid X receptor, interacts with vitamin D response elements (VDREs) to regulate gene expression. Vitamin D deficiency due to insufficient sunlight exposure confers an increased risk for multiple sclerosis (MS). Objective: To study a protective role of vitamin D in multiple sclerosis (MS), it is important to characterize the global molecular network of VDR target genes (VDRTGs) in immune cells. Methods: We identified genome-wide VDRTGs collectively from two distinct chromatin immunoprecipitation followed by deep sequencing (ChIP-Seq) datasets of VDR-binding sites derived from calcitriol-treated human cells of B cell and monocyte origins. We mapped short reads of next generation sequencing (NGS) data on hg19 with Bowtie, detected the peaks with Model-based Analysis of ChIP-Seq (MACS), and identified genomic locations by GenomeJack, a novel genome viewer for NGS platforms. Results: We found 2997 stringent peaks distributed on protein-coding genes, chiefly located in the promoter and the intron on VDRE DR3 sequences. However, the corresponding transcriptome data verified calcitriol-induced upregulation of only a small set of VDRTGs. The molecular network of 1541 calcitriol-responsive VDRTGs showed a significant relationship with leukocyte transendothelial migration, Fcγ receptor-mediated phagocytosis, and transcriptional regulation by VDR, suggesting a pivotal role of genome-wide VDRTGs in immune regulation. Conclusion: These results suggest the working hypothesis that persistent deficiency of vitamin D might perturb the complex network of VDRTGs in immune cells, being responsible for induction of an autoimmune response causative for MS.


Vitamin D ◽  
2018 ◽  
pp. 141-174
Author(s):  
J. Wesley Pike ◽  
Mark B. Meyer ◽  
Seong M. Lee ◽  
Melda Onal ◽  
Nancy A. Benkusky

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