Identification of a vitamin D response element in the proximal promoter of the chicken carbonic anhydrase II gene.
The carbonic anhydrase II gene, whose transcription is enhanced by 1, 25-dihydroxyvitamin D3 (1,25-(OH)2D3), encodes an important enzyme in bone-resorbing cells derived from the fusion of monocytic progenitors. We analyzed the 1,25-(OH)2D3-mediated activation of the avian gene by transient transfection assays with promoter/reporter constructs into HD11 chicken macrophages and by DNA mobility shift assays. Deletion and mobility shift analyses indicated that the -62/-29 region confers 1,25-(OH)2D3 responsiveness and forms DNA-protein complexes. The addition of an anti-vitamin D receptor (VDR) antibody inhibited binding to this sequence, whereas anti-retinoid X receptor (RXR) antibody generated a lower mobility complex. Therefore, we concluded that this element binds a VDR.RXR heterodimer, but the addition of extra 1,25-(OH)2D3 had no effect on the formation of this complex. Moreover, the use of nuclear extracts from 1,25-(OH)2D3-treated macrophages led to the formation of an additional high mobility complex also composed of VDR.RXR heterodimer. Mutations provided evidence that the 1, 25-(OH)2D3-mediated activation of the carbonic anhydrase II gene is mediated by VDR.RXR heterodimers bound to a DR3-type vitamin D response element with sequence AGGGCAtggAGTTCG. This vitamin D response element is also functional in the ROS 17/2.8 osteoblasts.
Quélo
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Laboratoire de Biologie Moléculaire et Cellulaire de l'Ecole Normale Supérieure de Lyon, Unité Mixte de Recherche 49 CNRS, Ecole Normale Supérieure, Institut National de la Recherche agronomique 913, 46, Allée d'Italie, 69364 Lyon cédex 07, France.
Machuca
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Jurdic
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D000818:Animals; D001483:Base Sequence; D002256:Carbonic Anhydrases / Q000235:genetics*; D002467:Cell Nucleus / Q000378:metabolism; D002645:Chickens; D019175:DNA Methylation; D004268:DNA-Binding Proteins / Q000378:metabolism; D019281:Dimerization; D016296:Mutagenesis; D011401:Promoter Regions, Genetic; D051381:Rats; D012045:Regulatory Sequences, Nucleic Acid; D014407:Tumor Cells, Cultured; D014809:Vitamin D-Binding Protein / Q000737:chemistry* / Q000378:metabolism
D004268:DNA-Binding Proteins; D014809:Vitamin D-Binding Protein; D002256:Carbonic Anhydrases