Development of an environmentally responsive fluorescent ligand for vitamin D receptor.

Vitamin D receptor (VDR) plays a critical role in regulating multiple biological processes, including bone metabolism and cell differentiation, by mediating transcriptional activation in response to ligand binding. We have constructed an environmentally fluorescent probe 2 for VDR to facilitate real-time observation of its ligand-dependent conformational changes in living cells. This probe 2 was synthesized by introducing a dansyl fluorophore via an ethynyl group at the C11 position of 1α,25(OH)2D3. Probe 2 exhibited strong environmentally responsive fluorescence, showing increased intensity and a blue shift of the peak wavelength upon binding to VDR due to the increased hydrophobicity of the environment.