title: Transcription enhancer factor 1 binds multiple muscle MEF2 and A/T-rich elements during fast-to-slow skeletal muscle fiber type transitions.
abstract: In adult mouse skeletal muscle, beta-myosin heavy chain (betaMyHC) gene expression is primarily restricted to slow type I fibers; however, its expression can be induced in fast type II fibers in response to a sustained increase in load-bearing work (mechanical overload [MOV]). Our previous betaMyHC transgenic and protein-DNA interaction studies have identified an A/T-rich element (betaA/T-rich -269/-258) that is required for slow muscle expression and which potentiates MOV responsiveness of a 293-bp betaMyHC promoter (beta293wt). Despite the GATA/MEF2-like homology of this element, we found binding of two unknown proteins that were antigenically distinct from GATA and MEF2 isoforms. By using the betaA/T-rich element as bait in a yeast one-hybrid screen of an MOV-plantaris cDNA library, we identified nominal transcription enhancer factor 1 (NTEF-1) as the specific betaA/T-rich binding factor. Electrophoretic mobility shift assay analysis confirmed that NTEF-1 represents the enriched binding activity obtained only when the betaA/T-rich element is reacted with MOV-plantaris nuclear extract. Moreover, we show that TEF proteins bind MEF2 elements located in the control region of a select set of muscle genes. In transient-coexpression assays using mouse C2C12 myotubes, TEF proteins transcriptionally activated a 293-bp betaMyHC promoter devoid of any muscle CAT (MCAT) sites, as well as a minimal thymidine kinase promoter-luciferase reporter gene driven by three tandem copies of the desmin MEF2 or palindromic Mt elements or four tandem betaA/T-rich elements. These novel findings suggest that in addition to exerting a regulatory effect by binding MCAT elements, TEF proteins likely contribute to regulation of skeletal, cardiac, and smooth muscle gene networks by binding select A/T-rich and MEF2 elements under basal and hypertrophic conditions.
authors.affiliation: Department of Biochemistry, School of Medicine, University of Missouri-Columbia, 1600 Rollins Road, Columbia, MO 65211, USA.
authors.forename: Natalia
authors.initials: N
authors.lastname: Karasseva
authors.forename: Gretchen
authors.initials: G
authors.lastname: Tsika
authors.forename: Juan
authors.initials: J
authors.lastname: Ji
authors.forename: Aijing
authors.initials: A
authors.lastname: Zhang
authors.forename: Xiaoqing
authors.initials: X
authors.lastname: Mao
authors.forename: Richard
authors.initials: R
authors.lastname: Tsika
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D015152:Blotting, Northern; D015153:Blotting, Western; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D015723:Gene Library; D017930:Genes, Reporter; D006801:Humans; D008156:Luciferases / Q000378:metabolism; D064326:MEF2 Transcription Factors; D051379:Mice; D008957:Models, Genetic; D008969:Molecular Sequence Data; D018656:Muscle Fibers, Fast-Twitch / Q000378:metabolism*; D018657:Muscle Fibers, Slow-Twitch / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism*; D016296:Mutagenesis; D018006:Myogenic Regulatory Factors; D009687:Nuclear Proteins; D009841:Oligonucleotides / Q000235:genetics; D010957:Plasmids / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D020033:Protein Isoforms; D051381:Rats; D000091262:TEA Domain Transcription Factors; D013937:Thymidine Kinase / Q000378:metabolism; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D015533:Transcriptional Activation; D014162:Transfection; D020798:Two-Hybrid System Techniques
chemical_list: D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D064326:MEF2 Transcription Factors; D018006:Myogenic Regulatory Factors; D009687:Nuclear Proteins; D009841:Oligonucleotides; D020033:Protein Isoforms; D000091262:TEA Domain Transcription Factors; C057182:TEAD1 protein, human; D014157:Transcription Factors; D008156:Luciferases; D013937:Thymidine Kinase