The vitamin D receptor: new paradigms for the regulation of gene expression by 1,25-dihydroxyvitamin D3.

This article represents a summary of what is known of the VDR protein and its molecular mechanism of action at target genes. New methodologies now used, such as ChIP-chip and ChIP-seq, as well as novel reporter studies using large BAC clones stably transfected into culture cells or introduced as transgenes in mice, are providing new insights into how 1,25(OH)2D3-activated VDR modulates the expression of genes at single gene loci and at the level of gene networks. Many of these insights are unexpected and suggest that gene regulation is even more complex than previously appreciated. These studies also highlight new technologies and their central role in establishing fundamental biologic principles.