title: Gli2 and MEF2C activate each other's expression and function synergistically during cardiomyogenesis in vitro.
abstract: The transcription factors Gli2 (glioma-associated factor 2), which is a transactivator of Sonic Hedgehog (Shh) signalling, and myocyte enhancer factor 2C (MEF2C) play important roles in the development of embryonic heart muscle and enhance cardiomyogenesis in stem cells. Although the physiological importance of Shh signalling and MEF2 factors in heart development is well known, the mechanistic understanding of their roles is unclear. Here, we demonstrate that Gli2 and MEF2C activated each other's expression while enhancing cardiomyogenesis in differentiating P19 EC cells. Furthermore, dominant-negative mutant proteins of either Gli2 or MEF2C repressed each other's expression, while impairing cardiomyogenesis in P19 EC cells. In addition, chromatin immunoprecipitation (ChIP) revealed association of Gli2 to the Mef2c gene, and of MEF2C to the Gli2 gene in differentiating P19 cells. Finally, co-immunoprecipitation studies showed that Gli2 and MEF2C proteins formed a complex, capable of synergizing on cardiomyogenesis-related promoters containing both Gli- and MEF2-binding elements. We propose a model whereby Gli2 and MEF2C bind each other's regulatory elements, activate each other's expression and form a protein complex that synergistically activates transcription, enhancing cardiac muscle development. This model links Shh signalling to MEF2C function during cardiomyogenesis and offers mechanistic insight into their in vivo functions.
authors.affiliation: Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Canada.
authors.forename: Anastassia
authors.initials: A
authors.lastname: Voronova
authors.forename: Ashraf
authors.initials: A
authors.lastname: Al Madhoun
authors.forename: Anna
authors.initials: A
authors.lastname: Fischer
authors.forename: Michael
authors.initials: M
authors.lastname: Shelton
authors.forename: Christina
authors.initials: C
authors.lastname: Karamboulas
authors.forename: Ilona Sylvia
authors.initials: IS
authors.lastname: Skerjanc
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D053595:Embryonic Stem Cells / Q000166:cytology / Q000378:metabolism; D006321:Heart / Q000196:embryology; D051741:Kruppel-Like Transcription Factors / Q000235:genetics / Q000378:metabolism*; D064326:MEF2 Transcription Factors; D051379:Mice; D008822:Mice, Transgenic; D024510:Muscle Development / Q000235:genetics*; D032383:Myocytes, Cardiac / Q000166:cytology / Q000378:metabolism*; D018006:Myogenic Regulatory Factors / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D015533:Transcriptional Activation; D000075746:Zinc Finger Protein Gli2
chemical_list: C000618551:Gli2 protein, mouse; D051741:Kruppel-Like Transcription Factors; D064326:MEF2 Transcription Factors; C578041:Mef2c protein, mouse; D018006:Myogenic Regulatory Factors; D000075746:Zinc Finger Protein Gli2