title: CREB-1alpha is recruited to and mediates upregulation of the cytochrome c promoter during enhanced mitochondrial biogenesis accompanying skeletal muscle differentiation.
abstract: To further understand pathways coordinating the expression of nuclear genes encoding mitochondrial proteins, we studied mitochondrial biogenesis during differentiation of myoblasts to myotubes. This energy-demanding process was accompanied by a fivefold increase of ATP turnover, covered by an eightfold increase of mitochondrial activity. While no change in mitochondrial DNA copy number was observed, mRNAs as well as proteins for nucleus-encoded cytochrome c, cytochrome c oxidase subunit IV, and mitochondrial transcription factor A (TFAM) increased, together with total cellular RNA and protein levels. Detailed analysis of the cytochrome c promoter by luciferase reporter, binding affinity, and electrophoretic mobility shift assays as well as mutagenesis studies revealed a critical role for cyclic AMP responsive element binding protein 1 (CREB-1) for promoter activation. Expression of two CREB-1 isoforms was observed by using specific antibodies and quantitative reverse transcription-PCR, and a shift from phosphorylated CREB-1Delta in myoblasts to phosphorylated CREB-1alpha protein in myotubes was shown, while mRNA ratios remained unchanged. Chromatin immunoprecipitation assays confirmed preferential binding of CREB-1alpha in situ to the cytochrome c promoter in myotubes. Overexpression of constitutively active and dominant-negative forms supported the key role of CREB-1 in regulating the expression of genes encoding mitochondrial proteins during myogenesis and probably also in other situations of enhanced mitochondrial biogenesis.
authors.affiliation: Institute of Vegetative Physiology, Medical Faculty, University of Köln, Robert-Koch-Strasse 39, 50931 Köln, Germany.
authors.forename: Andras
authors.initials: A
authors.lastname: Franko
authors.forename: Sabine
authors.initials: S
authors.lastname: Mayer
authors.forename: Gerald
authors.initials: G
authors.lastname: Thiel
authors.forename: Ludovic
authors.initials: L
authors.lastname: Mercy
authors.forename: Thierry
authors.initials: T
authors.lastname: Arnould
authors.forename: Hue-Tran
authors.initials: HT
authors.lastname: Hornig-Do
authors.forename: Rudolf J
authors.initials: RJ
authors.lastname: Wiesner
authors.forename: Steffi
authors.initials: S
authors.lastname: Goffart
mesh_terms: D051697:Activating Transcription Factor 1 / Q000235:genetics / Q000378:metabolism; D000818:Animals; D002454:Cell Differentiation; D002478:Cells, Cultured / Q000378:metabolism; D017362:Cyclic AMP Response Element-Binding Protein / Q000502:physiology*; D045304:Cytochromes c / Q000096:biosynthesis / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics; D003576:Electron Transport Complex IV / Q000235:genetics; D018507:Gene Expression Regulation, Developmental / Q000235:genetics*; D017930:Genes, Reporter; D006801:Humans; D051379:Mice; D008931:Mitochondria, Muscle / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000096:biosynthesis / Q000235:genetics; D024510:Muscle Development / Q000235:genetics / Q000502:physiology*; D018485:Muscle Fibers, Skeletal / Q000378:metabolism*; D032446:Myoblasts / Q000378:metabolism*; D010101:Oxygen Consumption; D010766:Phosphorylation; D011401:Promoter Regions, Genetic / Q000235:genetics; D020033:Protein Isoforms / Q000502:physiology; D011499:Protein Processing, Post-Translational; D051381:Rats; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics; D015854:Up-Regulation
chemical_list: D051697:Activating Transcription Factor 1; C497100:Atf1 protein, mouse; C492004:Creb1 protein, mouse; D017362:Cyclic AMP Response Element-Binding Protein; D004268:DNA-Binding Proteins; D024101:Mitochondrial Proteins; D020033:Protein Isoforms; C499631:TFAM protein, human; D014157:Transcription Factors; D045304:Cytochromes c; D003576:Electron Transport Complex IV