Vitamin D Receptor/VDR [D6]

Steroid receptors are ligand-dependent intracellular proteins that stimulate transcription of specific genes by binding to specific DNA sequences following activation by the appropriate hormone. The 1,25-dihydroxy-vitamin D3 receptor (VDR) belongs to the superfamily of steroid hormone receptors which includes estrogen, progesterone, glucocorticoid, androgen, and thyroid hormone receptors. Vitamin D modulates calcium and phosphorus homeostasis, bone remodeling, cell growth regulation, and differentiation. Studies have found VDR in the intestine, bone, kidney, epidermis, and cells of the endocrine immune system. Repression of T-cell proliferation and interleukin-2 (IL-2) gene expresion, for example, occurs when VDR binds within the IL-2 enhancer. Formation of VDR/retinoic X receptor (RXR) heterodimers in the presence of intracellular 1,25(OH)2D3 has been shown to interfere with assembly of nuclear factor of activated T-cells (NFATp)/Fos/Jun/DNA complex and subsequent IL-2 gene transcription.