Analysis of 1,25-Dihydroxyvitamin D Genomic Action Reveals Calcium-Regulating and Calcium-Independent Effects in Mouse Intestine and Human Enteroids.

Although vitamin D is critical for the function of the intestine, most studies have focused on the duodenum. We show that transgenic expression of the vitamin D receptor (VDR) only in the distal intestine of VDR null mice (KO/TG mice) results in the normalization of serum calcium and rescue of rickets. Although it had been suggested that calcium transport in the distal intestine involves a paracellular process, we found that the 1,25-dihydroxyvitamin D [1,25(OH)D]-activated genes in the proximal intestine associated with active calcium transport (, , and ) are also induced by 1,25(OH)D in the distal intestine of KO/TG mice. In addition, , encoding a manganese efflux transporter, was one of the genes most induced by 1,25(OH)D in both proximal and distal intestine. Both villus and crypt were found to express and VDR target genes. RNA sequence (RNA-seq) analysis of human enteroids indicated that the effects of 1,25(OH)D observed in mice are conserved in humans. Using mice, a loss of cortical bone and a marked decrease in and in the intestine was observed. Our findings suggest an interrelationship between vitamin D and intestinal Mn efflux and indicate the importance of distal intestinal segments to vitamin D action.