Vitamin D receptor

Transcription factor activated by vitamin D

The vitamin D receptor (VDR also known as the calcitriol receptor) is a member of the nuclear receptor family of transcription factors. Calcitriol (the active form of vitamin D, 1,25 (OH)2vitamin D3) binds to VDR, which then forms a heterodimer with the retinoid X receptor. The VDR heterodimer then enters the nucleus and binds to Vitamin D responsive elements (VDRE) in genomic DNA. VDR binding results in expression or transrepression of many specific gene products. VDR is also involved in microRNA directed post transcriptional mechanisms. In humans, the vitamin D receptor is encoded by the VDR gene located on chromosome 12q13.11. VDR is expressed in most tissues of the body, and regulates transcription of genes involved in intestinal and renal transport of calcium and other minerals. Glucocorticoids decrease VDR expression.

The VDR gene encodes the nuclear hormone receptor for vitamin D. The most potent natural agonist is calcitriol and the vitamin D2 homologue ercalcitriol, ) is also a strong activator. Other forms of vitamin D bind with lower affinity, as does the secondary bile acid lithocholic acid. The receptor belongs to the family of trans acting transcriptional regulatory factors and shows similarity of sequence to the steroid and thyroid hormone receptors. Downstream targets of this nuclear hormone receptor include many genes involved in mineral metabolism. FokI polymorphism is a risk factor for enveloped virus infection as revealed in a meta analysis. The importance of this gene has also been noted in the natural aging process were 3’UTR haplotypes of the gene showed an association with longevity.