title: NKX2-5 regulates the expression of beta-catenin and GATA4 in ventricular myocytes.
abstract: BACKGROUND
  The molecular pathway that controls cardiogenesis is temporally and spatially regulated by master transcriptional regulators such as NKX2-5, Isl1, MEF2C, GATA4, and beta-catenin. The interplay between these factors and their downstream targets are not completely understood. Here, we studied regulation of beta-catenin and GATA4 by NKX2-5 in human fetal cardiac myocytes.
  
  
  RESULTS
  Using antisense inhibition we disrupted the expression of NKX2-5 and studied changes in expression of cardiac-associated genes. Down-regulation of NKX2-5 resulted in increased beta-catenin while GATA4 was decreased. We demonstrated that this regulation was conferred by binding of NKX2-5 to specific elements (NKEs) in the promoter region of the beta-catenin and GATA4 genes. Using promoter-luciferase reporter assay combined with mutational analysis of the NKEs we demonstrated that the identified NKX2-5 binding sites were essential for the suppression of beta-catenin, and upregulation of GATA4 by NKX2-5.
  
  
  CONCLUSIONS
  This study suggests that NKX2-5 modulates the beta-catenin and GATA4 transcriptional activities in developing human cardiac myocytes.
authors.affiliation: Labatt Family Heart Centre, Hospital for Sick Children, Toronto, Ontario, Canada. ali.riazi@sickkids.ca
authors.forename: Ali M
authors.initials: AM
authors.lastname: Riazi
authors.forename: Jun K
authors.initials: JK
authors.lastname: Takeuchi
authors.forename: Lisa K
authors.initials: LK
authors.lastname: Hornberger
authors.forename: Syed Hassan
authors.initials: SH
authors.lastname: Zaidi
authors.forename: Fariba
authors.initials: F
authors.lastname: Amini
authors.forename: John
authors.initials: J
authors.lastname: Coles
authors.forename: Benoit G
authors.initials: BG
authors.lastname: Bruneau
authors.forename: Glen S
authors.initials: GS
authors.lastname: Van Arsdell
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D047369:Chromatin Immunoprecipitation; D024202:Electrophoretic Mobility Shift Assay; D050991:GATA4 Transcription Factor / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation; D006352:Heart Ventricles / Q000166:cytology*; D006579:Heterozygote; D000072576:Homeobox Protein Nkx-2.5; D018398:Homeodomain Proteins / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008957:Models, Genetic; D008969:Molecular Sequence Data; D032383:Myocytes, Cardiac / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*; D051153:Wnt Proteins / Q000378:metabolism; D051176:beta Catenin / Q000235:genetics*
chemical_list: D050991:GATA4 Transcription Factor; C484170:GATA4 protein, human; D000072576:Homeobox Protein Nkx-2.5; D018398:Homeodomain Proteins; C095552:NKX2-5 protein, human; C484469:Nkx2-5 protein, mouse; D012333:RNA, Messenger; D014157:Transcription Factors; D051153:Wnt Proteins; D051176:beta Catenin