1,25-dihydroxyvitamin D3 stimulates cyclic vitamin D receptor/retinoid X receptor DNA-binding, co-activator recruitment, and histone acetylation in intact osteoblasts

1,25(OH)(2)D-3 induces gene expression through the VDR. We used chromatin immunoprecipitation techniques to explore this 1,25(OH)(2)D-3-induced process on the 25-hydroxyvitamin D-3-24-hydroxylase (Cyp24) and Opn gene promoters in intact osteoblasts. Our studies show that 1,25(OH)(2)D-3-induced transactivation is a dynamic process that involves promoter-specific localization of VDR and RXR, recruitment of histone acetyltransferase complexes, and in the case of the Cyp24 gene, modification of histone 4.