title: Morphogenesis of the right ventricle requires myocardial expression of Gata4.
abstract: Mutations in developmental regulatory genes have been found to be responsible for some cases of congenital heart defects. One such regulatory gene is Gata4, a zinc finger transcription factor. In order to circumvent the early embryonic lethality of Gata4-null embryos and to investigate the role of myocardial Gata4 expression in cardiac development, we used Cre/loxP technology to conditionally delete Gata4 in the myocardium of mice at an early and a late time point in cardiac morphogenesis. Early deletion of Gata4 by Nkx2-5Cre resulted in hearts with striking myocardial thinning, absence of mesenchymal cells within the endocardial cushions, and selective hypoplasia of the RV. RV hypoplasia was associated with downregulation of Hand2, a transcription factor previously shown to regulate formation of the RV. Cardiomyocyte proliferation was reduced, with a greater degree of reduction in the RV than in the LV. Late deletion of Gata4 by Cre recombinase driven by the alpha myosin heavy chain promoter did not selectively affect RV development or generation of endocardial cushion mesenchyme but did result in marked myocardial thinning with decreased cardiomyocyte proliferation, as well as double-outlet RV. Our results demonstrate a general role of myocardial Gata4 in regulating cardiomyocyte proliferation and a specific, stage-dependent role in regulating the morphogenesis of the RV and the atrioventricular canal.
authors.affiliation: Cardiovascular Division, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Elisabeth M
authors.initials: EM
authors.lastname: Zeisberg
authors.forename: Qing
authors.initials: Q
authors.lastname: Ma
authors.forename: Amy L
authors.initials: AL
authors.lastname: Juraszek
authors.forename: Kelvin
authors.initials: K
authors.lastname: Moses
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Schwartz
authors.forename: Seigo
authors.initials: S
authors.lastname: Izumo
authors.forename: William T
authors.initials: WT
authors.lastname: Pu
mesh_terms: D000818:Animals; D049109:Cell Proliferation; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D050991:GATA4 Transcription Factor; D018507:Gene Expression Regulation, Developmental; D006330:Heart Defects, Congenital / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D006352:Heart Ventricles / Q000166:cytology / Q000196:embryology*; D000072576:Homeobox Protein Nkx-2.5; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D019426:Integrases / Q000235:genetics; D008648:Mesoderm / Q000166:cytology / Q000502:physiology; D051379:Mice; D008822:Mice, Transgenic; D009024:Morphogenesis / Q000235:genetics / Q000502:physiology*; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000166:cytology / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014764:Viral Proteins / Q000235:genetics
chemical_list: D004268:DNA-Binding Proteins; D050991:GATA4 Transcription Factor; C484171:Gata4 protein, mouse; D000072576:Homeobox Protein Nkx-2.5; D018398:Homeodomain Proteins; C484469:Nkx2-5 protein, mouse; D014157:Transcription Factors; D014764:Viral Proteins; C045073:Cre recombinase; D019426:Integrases