Transcriptional control of vitamin D-regulated proteins.

Vitamin D is a physiological regulator of gene transcription associated with control of a broad spectrum of biological processes that include but is not restricted to growth, differentiation and calcium-mediated homeostatic control. Transcriptional regulation is mediated by sequence-specific interactions of a 1,25(OH)2D3-vitamin D receptor-accessory factor complex with vitamin D responsive elements (VDRE) residing in the promoters of hormone responsive genes. Functioning primarily as a transcription enhancer, activity at the VDRE is controlled by diverse and integrated cellular signalling pathways acting synergistically and/or antagonistically with a series of basal regulatory elements and other hormone regulated sequences that are components of modularly organized vitamin D-responsive gene promoters. Molecular mechanisms that integrate the activities at promoter elements contributing to vitamin D-related transcriptional control include overlapping transcription factor binding domains within regulatory elements and cooperative activities at independent regulatory sequences that determine the level of vitamin D responsiveness.