[Current Topics on Vitamin D. Mechanism of molecular action of vitamin D via its nuclear receptor]

Most of vitamin D actions mediate expression of target genes regulated by nuclear vitamin D receptor (VDR). Regulation of chromatin environment has emerged to underlie gene regulation by liganded VDR. Active state of chromatin is defined by specific combination of post-translational modification of histone proteins, and chromatin remodelers as nuclear complexes conduct dynamic shift of chromatin sate. Among histone modifications, methylations of specific lysine residues located in the N-terminal tails of histone H3 are known to play pivotal roles in directing chromatin state, and the methylated lysine 4 and 9 in the histone H3 (H3K4me and H3K9me) are widely used as indicators of chromatin state. The histone modifying enzymes and chromatin remodelers are thus regulators for chromatin environment, and overtly co-regulate transcriptional regulations of a particular set of target genes by nuclear receptors including VDR. In this review, the molecular mechanism of regulated chromatin configuration is described by illustrating modifications of histone proteins and rearrangements of nucleosome array and their regulators.