Identification of a 1,25-Dihydroxyvitamin D3-Response Element in the 5' Flanking Region of the Rat Calbindin D-9k Gene

The rat calbindin D-9k gene is transcriptionally regulated by 1,25-dihydroxyvitamin D3in the intestine. We have examined the 5'-flanking region of this gene and identified a 1,25-dihydroxyvitamin D3-responsive element (DRE) between nucleotides -489 and -445. This element confers 1,25-dihydroxyvitamin D3responsiveness through its native promoter and the heterologous thymidine kinase promoter, and it contains the sequence GGGTGTCGGAAGCCC, which is homologous to the other previously identified DREs. Incubation of this element with the 1,25-dihydroxyvitamin D3receptor produced a specific protein-DNA complex, which shifted to a higher molecular weight form upon the addition of a monoclonal antibody specific to the 1,25-dihydroxyvitamin D3receptor. Therefore, the 5'-flanking region of the rat calbindin D-9k gene contains a DRE that mediates the enhanced expression of this gene by 1,25-dihydroxyvitamin D3in the intestine.