Calcitriol receptor

The calcitriol receptor, also known as the is_associated_with::vitamin D receptor (VDR) and also known as NR1I1 (nuclear receptor subfamily 1, group I, member 1), is a member of the is_associated_with::nuclear receptor family of is_associated_with::transcription factors. Upon activation by vitamin D, the VDR forms a is_associated_with::heterodimer with the is_associated_with::retinoid-X receptor and binds to is_associated_with::hormone response elements on is_associated_with::DNA resulting in expression or is_associated_with::transrepression of specific is_associated_with::geneproducts. The VDR not only regulates transcriptional responses but also involved in is_associated_with::microRNA-directed post transcriptional mechanisms. In humans, the vitamin D receptor is encoded by the VDR is_associated_with::gene.

is_associated_with::Glucocorticoids are known to decrease expression of VDR, which is expressed in most tissues of the body and regulate is_associated_with::intestinal transport of is_associated_with::calcium, is_associated_with::Iron and other minerals.

Function
This gene encodes the nuclear hormone receptor for vitamin D3. This receptor also functions as a receptor for the secondary is_associated_with::bile acid is_associated_with::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 are involved principally in mineral metabolism though the receptor regulates a variety of other metabolic pathways, such as those involved in the immune response and cancer.

Mutations in this gene are associated with type II vitamin D-resistant is_associated_with::rickets. A single nucleotide polymorphism in the initiation codon results in an alternate translation start site three codons downstream. Alternative splicing results in multiple transcript variants encoding the same protein.

The vitamin D receptor plays an important role in regulating the hair cycle. Loss of VDR is associated with hair loss in experimental animals. Experimental studies have shown that the unliganded VDR interacts with regulatory regions in cWnt (is_associated_with::wnt signaling pathway) and is_associated_with::sonic hedgehog target genes and is required for the induction of these pathways during the postnatal hair cycle. These studies have revealed novel actions of the unliganded VDR in regulating the post-morphogenic hair cycle.

Interactions
Calcitriol receptor has been shown to interact with


 * is_associated_with::BAG1,
 * is_associated_with::BAZ1B,
 * CAV3,
 * is_associated_with::MED1,
 * is_associated_with::MED12,
 * NCOR2,
 * NCOA2,
 * RXRA,
 * is_associated_with::RUNX1,
 * is_associated_with::RUNX1T1,
 * is_associated_with::SNW1,
 * is_associated_with::STAT1, and
 * ZBTB16.