title: Zebrafish cardiac development requires a conserved secondary heart field.
abstract: The secondary heart field is a conserved developmental domain in avian and mammalian embryos that contributes myocardium and smooth muscle to the definitive cardiac arterial pole. This field is part of the overall heart field and its myocardial component has been fate mapped from the epiblast to the heart in both mammals and birds. In this study we show that the population that gives rise to the arterial pole of the zebrafish can be traced from the epiblast, is a discrete part of the mesodermal heart field, and contributes myocardium after initial heart tube formation, giving rise to both smooth muscle and myocardium. We also show that Isl1, a transcription factor associated with undifferentiated cells in the secondary heart field in other species, is active in this field. Furthermore, Bmp signaling promotes myocardial differentiation from the arterial pole progenitor population, whereas inhibiting Smad1/5/8 phosphorylation leads to reduced myocardial differentiation with subsequent increased smooth muscle differentiation. Molecular pathways required for secondary heart field development are conserved in teleosts, as we demonstrate that the transcription factor Tbx1 and the Sonic hedgehog pathway are necessary for normal development of the zebrafish arterial pole.
authors.affiliation: Department of Pediatrics, Duke University, Durham, NC 27710, USA.
authors.forename: Danyal
authors.initials: D
authors.lastname: Hami
authors.forename: Adrian C
authors.initials: AC
authors.lastname: Grimes
authors.forename: Huai-Jen
authors.initials: HJ
authors.lastname: Tsai
authors.forename: Margaret L
authors.initials: ML
authors.lastname: Kirby
mesh_terms: D000818:Animals; D019485:Bone Morphogenetic Proteins / Q000378:metabolism*; D002454:Cell Differentiation; D005855:Germ Layers; D006321:Heart / Q000196:embryology* / Q000254:growth & development*; D053823:Hedgehog Proteins / Q000378:metabolism; D018398:Homeodomain Proteins / Q000378:metabolism; D060850:LIM-Homeodomain Proteins; D024510:Muscle Development; D009130:Muscle, Smooth / Q000196:embryology; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D010766:Phosphorylation; D015398:Signal Transduction; D051898:Smad1 Protein / Q000378:metabolism; D051902:Smad5 Protein / Q000378:metabolism; D051904:Smad8 Protein / Q000378:metabolism; D020825:T-Box Domain Proteins / Q000378:metabolism; D014157:Transcription Factors; D015027:Zebrafish / Q000196:embryology* / Q000378:metabolism; D029961:Zebrafish Proteins / Q000378:metabolism
chemical_list: D019485:Bone Morphogenetic Proteins; D053823:Hedgehog Proteins; D018398:Homeodomain Proteins; D060850:LIM-Homeodomain Proteins; D051898:Smad1 Protein; D051902:Smad5 Protein; D051904:Smad8 Protein; D020825:T-Box Domain Proteins; D014157:Transcription Factors; D029961:Zebrafish Proteins; C063843:insulin gene enhancer binding protein Isl-1; C497801:smad5 protein, zebrafish