1,25-Dihydroxyvitamin D-Responsive Element and Glucocorticoid Repression in the Osteocalcin Gene

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Abstract
The active hormonal form of vitamin D 3 , 1,25-dihydroxyvitamin D 3 [1,25(OH), which regulates cellular replication and function in many tissues and has a role in bone and calcium homeostasis, acts through a hormone receptor homologous with other steroid and thyroid hormone receptors. A 1,25(OH) 2 D 3 -responsive element (VDRE), which is within the promoter for osteocalcin [a bone protein induced by 1,25(OH) 2 D 3 ] is unresponsive to other steroid hormones, can function in a heterologous promoter, and contains a doubly palindromic DNA sequence (TT GGTGA C TCACC G GGTGA AC; -513 to -493 bp), with nucleotide sequence homology to other hormone responsive elements. The potent glucocorticoid repression of 1,25(OH) 2 D 3 induction and of basal activity of this promoter acts through a region between -196 and +34 bp, distinct from the VDRE.