title: Cardiomyocyte differentiation by GATA-4-deficient embryonic stem cells.
abstract: In situ hybridization studies, promoter analyses and antisense RNA experiments have implicated transcription factor GATA-4 in the regulation of cardiomyocyte differentiation. In this study, we utilized Gata4-/- embryonic stem (ES) cells to determine whether this transcription factor is essential for cardiomyocyte lineage commitment. First, we assessed the ability of Gata4-/- ES cells form cardiomyocytes during in vitro differentiation of embryoid bodies. Contracting cardiomyocytes were seen in both wild-type and Gata4-/- embryoid bodies, although cardiomyocytes were observed more often in wild type than in mutant embryoid bodies. Electron microscopy of cardiomyocytes in the Gata4-/- embryoid bodies revealed the presence of sarcomeres and junctional complexes, while immunofluorescence confirmed the presence of cardiac myosin. To assess the capacity of Gata4-/- ES cells to differentiate into cardiomyocytes in vivo, we prepared and analyzed chimeric mice. Gata4-/- ES cells were injected into 8-cell-stage embryos derived from ROSA26 mice, a transgenic line that expresses beta-galactosidase in all cell types. Chimeric embryos were stained with X-gal to discriminate ES cell- and host-derived tissue. Gata4-/- ES cells contributed to endocardium, myocardium and epicardium. In situ hybridization showed that myocardium derived from Gata4-/- ES cells expressed several cardiac-specific transcripts, including cardiac alpha-myosin heavy chain, troponin C, myosin light chain-2v, Nkx-2.5/Csx, dHAND, eHAND and GATA-6. Taken together these results indicate that GATA-4 is not essential for terminal differentiation of cardiomyocytes and suggest that additional GATA-binding proteins known to be in cardiac tissue, such as GATA-5 or GATA-6, may compensate for a lack of GATA-4.
authors.affiliation: Department of Pediatrics, Washington University School of Medicine, St. Louis Children's Hospital, MO 63110, USA.
authors.forename: N
authors.initials: N
authors.lastname: Narita
authors.forename: M
authors.initials: M
authors.lastname: Bielinska
authors.forename: D B
authors.initials: DB
authors.lastname: Wilson
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D002678:Chimera; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004622:Embryo, Mammalian / Q000502:physiology* / Q000648:ultrastructure; D050991:GATA4 Transcription Factor; D006321:Heart / Q000196:embryology*; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D009206:Myocardium / Q000166:cytology*; D015388:Organelles / Q000502:physiology / Q000648:ultrastructure; D013234:Stem Cells; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D016335:Zinc Fingers; D001616:beta-Galactosidase / Q000096:biosynthesis
chemical_list: D004268:DNA-Binding Proteins; D050991:GATA4 Transcription Factor; D014157:Transcription Factors; D001616:beta-Galactosidase