title: Preferential binding of MyoD-E12 versus myogenin-E12 to the murine sarcoma virus enhancer in vitro.
abstract: The MyoD family of transcription factors regulates muscle-specific gene expression in vertebrates. In the adult rat, MyoD mRNA accumulates predominately in fast-twitch muscle, in particular type IIb and/or IIx fibers, whereas Myogenin mRNA is restricted to slow-twitch type I muscle fibers. Transgenic mice expressing the avian v-ski oncogene from the murine sarcoma virus (MSV) promoter-enhancer display preferential hypertrophy of type IIb fast-twitch muscle apparently because of the restricted expression of the transgene. We tested the hypothesis that preferential interactions of MyoD, as a heterodimer with E12, with the MSV enhancer, which has six E-box targets for MyoD family proteins, could contribute to v-ski gene expression in IIb muscle fibers. A series of quantitative binding studies was performed using an electrophoretic mobility shift assay to test MyoD-E12 versus Myogenin-E12 binding to the MSV enhancer. Our results indicate that MyoD-E12 binds the MSV enhancer with higher affinity and higher cooperativity than Myogenin-E12. Interestingly, MyoD-E12 bound all of the individual E-boxes tested with positive cooperativity indicating DNA-mediated dimerization of the protein subunits.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, 72205, USA.
authors.forename: P J
authors.initials: PJ
authors.lastname: Czernik
authors.forename: C A
authors.initials: CA
authors.lastname: Peterson
authors.forename: B K
authors.initials: BK
authors.lastname: Hurlburt
mesh_terms: D000818:Animals; D001483:Base Sequence; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D004742:Enhancer Elements, Genetic; D015967:Gene Expression Regulation, Viral; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D017570:MyoD Protein / Q000378:metabolism*; D018008:Myogenin / Q000378:metabolism*; D015682:Retroviridae Proteins, Oncogenic / Q000378:metabolism; D009053:Sarcoma Viruses, Murine / Q000235:genetics*; D017384:Sequence Deletion; D013329:Structure-Activity Relationship; D051820:TCF Transcription Factors; D058125:Transcription Factor 7-Like 1 Protein; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; D017570:MyoD Protein; C503801:Myog protein, mouse; D018008:Myogenin; D015682:Retroviridae Proteins, Oncogenic; D051820:TCF Transcription Factors; C544913:Tcf7l1 protein, mouse; C553060:Tcf7l1 protein, rat; D058125:Transcription Factor 7-Like 1 Protein; D014157:Transcription Factors; C070358:v-ski protein, Avian retrovirus; D004247:DNA