Functional regulatory regions of human transcription factor MEF2C.
Myocyte enhancer-binding factor 2C (MEF2C), a transcription factor expressed at high levels in muscle and brain, is implicated in the terminal differentiation and post-mitotic survival of neurons. In this study MEF2C deletion mutants and naturally-occurring isoforms were transfected into COS and P19 cells with two different reporter genes, to test the relative transcriptional activities of the MEF2C constructs. Deletion of parts of the carboxy terminus, in particular amino acids 387-473, enhanced transcriptional activation. A region rich in serine, threonine, proline, and tyrosine from amino acids 312-367 was sufficient to activate transcription at low levels when coupled to amino acids 1-86, which contain the DNA-binding (MADS/MEF) domain of MEF2C, but also depended on amino acids 87-311 for full effect. A construct with amino acids 312-350 missing showed significantly less transcriptional activation than proteins containing this sequence. MEF2C constructs were uniformly localized to the cell nucleus by immunostaining with an antibody to the constant N-terminal region of MEF2C. Western blot and gel shift studies of extracts from transfected cells and from in vitro transcription/translation suggest that variation in the amount of protein expressed or in DNA-binding properties does not account for observed differences in transcriptional activation. This structural information may be useful for elucidating the mechanisms of MEF2C in interacting with other factors to regulate target genes.
Janson
C G
CG
Yale University School of Medicine, Department of Neurology, New Haven, CT 06510, USA.
Chen
Y
Y
Li
Y
Y
Leifer
D
D
D000818:Animals; D001665:Binding Sites; D015153:Blotting, Western; D019556:COS Cells; D002460:Cell Line; D002467:Cell Nucleus / Q000737:chemistry; D002522:Chlorocebus aethiops; D003402:Creatine Kinase / Q000096:biosynthesis / Q000235:genetics; D052283:Creatine Kinase, MM Form; D004247:DNA / Q000378:metabolism; D019281:Dimerization; D024202:Electrophoretic Mobility Shift Assay; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D006801:Humans; D007527:Isoenzymes / Q000096:biosynthesis / Q000235:genetics; D026161:MADS Domain Proteins; D064326:MEF2 Transcription Factors; D018006:Myogenic Regulatory Factors / Q000737:chemistry* / Q000502:physiology; D010446:Peptide Fragments / Q000737:chemistry; D020033:Protein Isoforms / Q000502:physiology; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D017384:Sequence Deletion; D013329:Structure-Activity Relationship; D014158:Transcription, Genetic; D014162:Transfection
D007527:Isoenzymes; D026161:MADS Domain Proteins; D064326:MEF2 Transcription Factors; C578040:MEF2C protein, human; D018006:Myogenic Regulatory Factors; D010446:Peptide Fragments; D020033:Protein Isoforms; D011993:Recombinant Fusion Proteins; D004247:DNA; D003402:Creatine Kinase; D052283:Creatine Kinase, MM Form