Characterization of 1,25-dihydroxyvitamin D3 receptor interactions with target sequences in the rat osteocalcin gene

• Published in: Molecular endocrinology (Baltimore, Md.) Vol. 6; no. 4; pp. 557 - 562
• Main Authors: DEMAY, M. B, KIERNAN, M. S, DELUCA, H. F, KRONENBERG, H. M
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Endocrine Society 01.04.1992
• Subjects: Animals; Base Sequence; Binding Sites; Binding, Competitive; Biological and medical sciences; Calcitriol - metabolism; Cell Line; Chromosome Deletion; DNA-Binding Proteins - metabolism; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation; Molecular and cellular biology; Molecular genetics; Molecular Sequence Data; Mutagenesis, Site-Directed; Oligodeoxyribonucleotides; Osteocalcin - genetics; Rats; Receptors, Calcitriol; Receptors, Steroid - metabolism; Repetitive Sequences, Nucleic Acid; Transcription, Genetic; Transcription. Transcription factor. Splicing. Rna processing; Transcriptional Activation; Transfection; Osteocalcin; Regulation(control); Gene; Cholecalciferol(1,25-dihydroxy); Transcription promoter; Regulatory sequence; Gene expression; Response element; Hybrid gene; Biological receptor
• ISSN: 0888-8809; 1944-9917
• DOI: 10.1210/me.6.4.557

The sequences in the rat osteocalcin gene that bind the 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] receptor and mediate its effects on gene transcription contain three copies of a motif homologous to those found in other steroid response elements. To evaluate the relative importance of these motifs and their flanking sequences, functional properties and receptor binding of a series of mutant response elements were analyzed. Mutations in the third motif, including its deletion, have no effect on receptor binding and only modestly detrimental effects on the ability of the upstream motifs to confer 1,25-(OH)2D3 responsiveness in transfected cells. Mutations in the first two motifs have negative effects on both receptor binding and gene activation. Mutagenesis of bases upstream from each of the first two motifs alters receptor binding and gene activation; these bases are, therefore, an integral part of the rat osteocalcin 1,25-(OH)2D3 response element. Two direct hexameric repeats (GGGTGA ATG AGGACA) and not the palindromic motif thus characterize this 1,25-(OH)2D3 response element.