title: Myocyte enhancer factor-2 and serum response factor binding elements regulate fast Myosin heavy chain transcription in vivo.
abstract: Adult fast muscle fibers express distinct myosin heavy chains (MyHC) in differing proportions, but the mechanisms underlying their differential expression remain undefined. We used a variety of in vitro and in vivo approaches to explore the contribution of transcriptional regulation to adult fast MyHC expression. Here we show that 800-1000 bp of a sequence upstream of the three mouse adult fast MyHC genes (Ia, IIb, and IId/x) are sufficient to drive muscle-specific and fiber-specific expression in vivo. We show that the upstream promoter region of the gene most abundantly expressed in mouse skeletal muscles, IIb MyHC, retains binding activity and transcriptional activation for three positive transcription factors, the serum response factor, Oct-1, and myocyte enhancer factor-2, whereas the other two genes (IIa and IId/x) have nucleotide substitutions in these sites that reduce binding and transcriptional activation. Finally, we demonstrate that regions upstream of 300 bp modulate the effects of these elements. Together, these data demonstrate that the quantitative differences in MyHC expression in mouse skeletal muscle have evolved at least in part through the elimination of positive-acting transcription factor binding sites.
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado 80309-0347, USA.
authors.forename: David L
authors.initials: DL
authors.lastname: Allen
authors.forename: Jesse N
authors.initials: JN
authors.lastname: Weber
authors.forename: Laura K
authors.initials: LK
authors.lastname: Sycuro
authors.forename: Leslie A
authors.initials: LA
authors.lastname: Leinwand
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000378:metabolism / Q000502:physiology*; D017353:Gene Deletion; D005786:Gene Expression Regulation; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008156:Luciferases / Q000378:metabolism; D064326:MEF2 Transcription Factors; D051379:Mice; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000201:enzymology; D009154:Mutation; D009206:Myocardium / Q000201:enzymology; D018006:Myogenic Regulatory Factors; D018995:Myosin Heavy Chains / Q000378:metabolism*; D050811:Octamer Transcription Factor-1; D009841:Oligonucleotides / Q000737:chemistry; D010957:Plasmids / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D020033:Protein Isoforms; D017434:Protein Structure, Tertiary; D026362:Serum Response Factor / Q000378:metabolism*; D014018:Tissue Distribution; D014157:Transcription Factors / Q000378:metabolism / Q000502:physiology*; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection
chemical_list: D004268:DNA-Binding Proteins; D064326:MEF2 Transcription Factors; D018006:Myogenic Regulatory Factors; D050811:Octamer Transcription Factor-1; D009841:Oligonucleotides; C494166:Pou2f1 protein, mouse; D020033:Protein Isoforms; D026362:Serum Response Factor; D014157:Transcription Factors; D049452:Green Fluorescent Proteins; D008156:Luciferases; D018995:Myosin Heavy Chains