title: A 5'-distal element mediates vitamin D-inducibility of PDGF-A gene transcription.
abstract: Expression of the platelet-derived growth factor-A subunit (PDGF-A) is regulated to a significant degree by DNA elements located in the 5'-distal region of the gene. A potent basal enhancer (ACE66) located approximately 7 kb upstream of the transcription start site contains a number of half-sites for nuclear receptor binding, two of which are arranged in the form of direct repeat-3 motif that corresponds to a consensus vitamin D response element (VDRE). Electrophoretic mobility shift assays confirmed that the ACE66 sequence was recognized as a high affinity target for binding of heterodimers of recombinant vitamin D receptor (VDR) and its partner, retinoid-X receptor-alpha (RXRalpha). VDRE activity was localized by transient transfection analysis to a direct repeat-3 motif within the 5'-portion of the ACE66 element. Moreover, 1,25-(OH)2D3 was validated as a regulator of the endogenous PDGF-A gene by the vitamin D-stimulated upregulation of PDGF-A mRNA levels in a VDR-expressing clone of JEG-3 cells. Thus, PDGF-A represents a novel mitogenic target of 1,25-(OH)2D3 whose expression is induced via binding of hormone-activated VDR to a response element located far upstream of the transcription start site.
authors.affiliation: Department of Molecular and Biomedical Pharmacology, University of Kentucky Medical Center, Lexington, KY 40536, USA.
authors.forename: Nancy
authors.initials: N
authors.lastname: Pedigo
authors.forename: Hongxing
authors.initials: H
authors.lastname: Zhang
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Koszewski
authors.forename: David M
authors.initials: DM
authors.lastname: Kaetzel
mesh_terms: D020816:Amino Acid Motifs; D001483:Base Sequence; D001665:Binding Sites; D019281:Dimerization; D004305:Dose-Response Relationship, Drug; D004742:Enhancer Elements, Genetic; D005786:Gene Expression Regulation; D006801:Humans; D008156:Luciferases / Q000378:metabolism; D008969:Molecular Sequence Data; D010957:Plasmids / Q000378:metabolism; D010982:Platelet-Derived Growth Factor / Q000096:biosynthesis* / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry; D020218:Response Elements; D012260:Ribonucleases / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection; D014807:Vitamin D / Q000494:pharmacology*
chemical_list: D010982:Platelet-Derived Growth Factor; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D011994:Recombinant Proteins; C075278:platelet-derived growth factor A; D014807:Vitamin D; D008156:Luciferases; D012260:Ribonucleases