title: A GATA-dependent right ventricular enhancer controls dHAND transcription in the developing heart.
abstract: Heart formation in vertebrates is believed to occur in a segmental fashion, with discreet populations of cardiac progenitors giving rise to different chambers of the heart. However, the mechanisms involved in specification of different chamber lineages are unclear. The basic helix-loop-helix transcription factor dHAND is expressed in cardiac precursors throughout the cardiac crescent and the linear heart tube, before becoming restricted to the right ventricular chamber at the onset of looping morphogenesis. dHAND is also expressed in the branchial arch neural crest, which contributes to craniofacial structures and the aortic arch arteries. Using a series of dHAND-lacZ reporter genes in transgenic mice, we show that cardiac and neural crest expression of dHAND are controlled by separate upstream enhancers and we describe a composite cardiac-specific enhancer that directs lacZ expression in a pattern that mimics that of the endogenous dHAND gene throughout heart development. Deletion analysis reduced this enhancer to a 1.5 kb region and identified subregions responsible for expression in the right ventricle and cardiac outflow tract. Comparison of mouse regulatory elements required for right ventricular expression to the human dHAND upstream sequence revealed two conserved consensus sites for binding of GATA transcription factors. Mutation of these sites abolished transgene expression in the right ventricle, identifying dHAND as a direct transcriptional target of GATA factors during right ventricle development. Since GATA factors are not chamber-restricted, these findings suggest the existence of positive and/or negative coregulators that cooperate with GATA factors to control right ventricular-specific gene expression in the developing heart.
authors.affiliation: Department of Molecular Biology, University of Texas Southwestern Medical Center at Dallas, 75390-9148, USA.
authors.forename: D G
authors.initials: DG
authors.lastname: McFadden
authors.forename: J
authors.initials: J
authors.lastname: Charité
authors.forename: J A
authors.initials: JA
authors.lastname: Richardson
authors.forename: D
authors.initials: D
authors.lastname: Srivastava
authors.forename: A B
authors.initials: AB
authors.lastname: Firulli
authors.forename: E N
authors.initials: EN
authors.lastname: Olson
mesh_terms: D000818:Animals; D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins; D017124:Conserved Sequence; D004247:DNA / Q000235:genetics; D017931:DNA Primers / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics*; D004742:Enhancer Elements, Genetic; D005318:Fetal Heart / Q000196:embryology* / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D006330:Heart Defects, Congenital / Q000196:embryology / Q000235:genetics; D006352:Heart Ventricles / Q000196:embryology / Q000378:metabolism; D006801:Humans; D007763:Lac Operon; D051379:Mice; D008810:Mice, Inbred C57BL; D008813:Mice, Inbred ICR; D008817:Mice, Mutant Strains; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism*; D014158:Transcription, Genetic; D029961:Zebrafish Proteins
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D004247:DNA; D017931:DNA Primers; D004268:DNA-Binding Proteins; D014157:Transcription Factors; D029961:Zebrafish Proteins; C498765:HAND2 protein, human; C498766:Hand2 protein, mouse; C410915:hand2 protein, zebrafish