Retinoid X receptor alpha (RXRA) (RXRA)

The Retinoid X receptor alpha (RXRA) is a member of the nuclear receptor superfamily that serves as an obligatory heterodimeric partner for the Vitamin D Receptor (VDR), forming a functional complex that regulates genes essential for calcium and phosphate homeostasis (UniProt P19793). The VDR-RXR interface is a specific structural region where the ligand-binding domains of both receptors interact, a process stabilized by the binding of 1,25-dihydroxyvitamin D3 to the VDR (PubMed: 22403325). This heterodimerization is a prerequisite for the complex to bind to Vitamin D Response Elements (VDREs) in the promoter regions of target genes, such as CYP24A1 and BGLAP, facilitating the recruitment of transcriptional coactivators (PubMed: 12110171). Dysregulation of this interface or its constituent proteins is implicated in metabolic bone diseases like osteoporosis and rickets, as well as in the pathogenesis of certain cancers and inflammatory skin conditions like psoriasis. Pharmacological agents targeting this system include VDR-specific agonists (e.g., Calcitriol) and RXR-selective rexinoids (e.g., Bexarotene), which modulate the conformational state of the heterodimer to achieve therapeutic effects (DrugBank DB00307). Research into the VDR-RXR interface is particularly focused on developing dissociated ligands that can trigger specific transcriptional pathways without inducing the dose-limiting side effect of hypercalcemia.

Other names

RXR-alphaNR2B1Nuclear receptor subfamily 2 group B member 1Retinoid X receptor alpha

Agonism of the RXR component or its partner VDR to induce heterodimerization, DNA binding to Vitamin D Response Elements (VDREs), and subsequent transcriptional activation or repression of target genes.