title: Regulation of inhibitor of differentiation gene 3 (Id3) expression by Sp2-motif binding factor in myogenic C2C12 cells: downregulation of DNA binding activity following skeletal muscle differentiation.
abstract: Id3 is a member of the Id family of transcriptional regulators that have been implicated in the development of multiple tissues. Altered expression of the Id genes and proteins contribute to carcinogenesis and atherosclerosis. Id3 is highly expressed in proliferating skeletal muscle cells but becomes downregulated upon terminal differentiation. We have identified several DNase I protected footprints within a proximal region of the mouse Id3 promoter that has been shown previously to support high levels of transcriptional activity in proliferating skeletal muscle cells. Two of these sites interacted, respectively, in vitro with Sp2 and Egr-1 proteins present in muscle cell nuclear extracts. Mutation analysis revealed that the Sp2 site accounted for a major part of the Id3 promoter activity in proliferating muscle cells whereas the Egr-1 site was dispensable. Consistent with the previously observed downregulation of the endogenous Id3 gene, protein binding to the Sp2 site was substantially reduced with extracts from differentiated muscle cells. Our results reveal Id3 as a potential target for Sp2 and raise the possibility that acute activation and the chronic and maintained expression of Id3 gene might be regulated by different mechanisms.
authors.affiliation: Department of Medical Pharmacology and Physiology and Molecular Biology Program, University of Missouri-Columbia, Columbia, MO 65201, USA.
authors.forename: Jinmei
authors.initials: J
authors.lastname: Wu
authors.forename: Robert W
authors.initials: RW
authors.lastname: Lim
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002454:Cell Differentiation / Q000502:physiology*; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism*; D018983:DNA Footprinting; D015536:Down-Regulation; D051766:Early Growth Response Protein 1 / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D005786:Gene Expression Regulation; D051796:Inhibitor of Differentiation Proteins / Q000096:biosynthesis*; D051379:Mice; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000166:cytology*; D011401:Promoter Regions, Genetic / Q000235:genetics; D051704:Sp2 Transcription Factor / Q000378:metabolism*
chemical_list: D051766:Early Growth Response Protein 1; C486109:Egr1 protein, mouse; D051796:Inhibitor of Differentiation Proteins; C067679:Idb3 protein, mouse; D051704:Sp2 Transcription Factor; D004247:DNA