VD/VDR

Vitamin D is a secosteroidalprohormone, it can be synthesized at sufficient levels in skin, given adequate skin exposure to UV B radiation from sunlight. Vitamin D modulates its biological effects by directly regulating target gene expression through the Vitamin D receptor (VDR), a ligand-regulated transcription factor and a member of the nuclear receptor superfamily. Whether synthesized in the skin or ingested, vitamin D requires two hydroxylation steps to become the biologically active hormone, 1,25-dyhydroxyvitamin D3 [1,25(OH)2D3], a form that signals through the VDR. The hormone-bound VDR modulates target gene transcription in response to vitamin D. VDR acts as a master transcriptional regulator of autophagy. Activation of the VDR by vitamin D induces autophagy and an autophagic transcriptional signature in breast cancer (BC) cells. There are 2 forms of vitamin D. Vitamin D2 (ergocalciferol) comes from irradiation of the yeast and plant sterol ergosterol, and vitamin D3 (cholecalciferol) is found in oily fish and cod liver oil and is made in the skin. Vitamin D represents vitamin D2 and vitamin D3. Topical agents containing active vitamin D3 (calcitriol, 1α, 25- dihydroxyvitaminD3, VD3) analogues such as Tacalcitol, Calcipotriol and Maxacalcitol are widely used for psoriasis therapy.