The vitamin D receptor (VDR) is a nuclear receptor that mediates calcitriol (active vitamin D3) signaling through a well-characterized mechanism 1. Upon vitamin D3 binding, VDR translocates to the nucleus and forms heterodimers with retinoid X receptor (RXR), enabling binding to vitamin D response elements and activation of target gene transcription 12. Beyond classical calcium homeostasis, VDR exhibits broader physiological roles. It functions as a receptor for secondary bile acid lithocholic acid and its metabolites 34. VDR expression is downregulated in pulmonary arterial hypertension, and calcitriol treatment restores expression while exerting antiproliferative effects in pulmonary artery smooth muscle cells through survivin and BMP signaling modulation 5. VDR polymorphisms associate with disease susceptibility: rs731236 and rs7975232 variants correlate with autism risk 6, while rs1989969 increases gastric cardiac adenocarcinoma risk in younger, alcohol-consuming populations 7. The rs1544410 BsmI polymorphism influences COVID-19 clinical severity 8. Conversely, in pancreatic cancer, elevated VDR expression paradoxically promotes tumor progression by upregulating CCL20, facilitating M2 macrophage polarization and recruitment 9. Additionally, VDR modulation through miR193a affects renin-angiotensin system activation and podocyte markers in kidney disease contexts 10.