title: The canonical Wingless signaling pathway is required but not sufficient for inflow tract formation in the Drosophila melanogaster heart.
abstract: The inflow tracts of the embryonic Drosophila cardiac tube, termed ostia, arise in its posterior three segments from cardiac cells that co-express the homeotic transcription factor Abdominal-A (abdA), the orphan nuclear receptor Seven-up (Svp), and the signaling molecule Wingless (Wg). To define the roles of these factors in inflow tract development, we assessed their function in inflow tract formation. We demonstrate, using several criteria, that abdA, svp, and wg are each critical for normal inflow tract formation. We further show that Wg acts in an autocrine manner to impact ostia fate, and that it mediates this effect at least partially through the canonical Wg signaling pathway. By contrast, neither wg expression nor Wg signaling are sufficient for inflow tract formation when expressed in anterior Svp cells that do not normally form inflow tracts in the embryo. Instead, ectopic abd-A expression throughout the cardiac tube is required for the formation of ectopic inflow tracts, indicating that autocrine Wg signaling must be supplemented by additional Hox-dependent factors to effect inflow tract formation. Taken together, these studies define important cellular and molecular events that contribute to cardiac inflow tract development in Drosophila. Given the broad conservation of the cardiac regulatory network through evolution, our studies provide insight into mechanisms of cardiac development in higher animals.
authors.affiliation: Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA; Sanford Burnham Medical Research Institute, Development and Aging Program, La Jolla, CA 92037, USA.
authors.forename: Gloriana V
authors.initials: GV
authors.lastname: Trujillo
authors.affiliation: Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA.
authors.forename: Dalea H
authors.initials: DH
authors.lastname: Nodal
authors.affiliation: Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA.
authors.forename: Candice V
authors.initials: CV
authors.lastname: Lovato
authors.affiliation: Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA.
authors.forename: Jill D
authors.initials: JD
authors.lastname: Hendren
authors.affiliation: Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA.
authors.forename: Lynda A
authors.initials: LA
authors.lastname: Helander
authors.affiliation: Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA.
authors.forename: TyAnna L
authors.initials: TL
authors.lastname: Lovato
authors.affiliation: Sanford Burnham Medical Research Institute, Development and Aging Program, La Jolla, CA 92037, USA.
authors.forename: Rolf
authors.initials: R
authors.lastname: Bodmer
authors.affiliation: Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA. Electronic address: rcripps@unm.edu.
authors.forename: Richard M
authors.initials: RM
authors.lastname: Cripps
mesh_terms: D000818:Animals; D001011:Aorta / Q000196:embryology; D003433:Crosses, Genetic; D004268:DNA-Binding Proteins / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D004331:Drosophila melanogaster / Q000196:embryology* / Q000235:genetics; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D005801:Genes, Homeobox / Q000235:genetics; D017344:Genes, Insect; D005819:Genetic Markers; D005838:Genotype; D006321:Heart / Q000196:embryology*; D006720:Homozygote; D017403:In Situ Hybridization; D009687:Nuclear Proteins / Q000378:metabolism; D011987:Receptors, Steroid / Q000378:metabolism; D015398:Signal Transduction; D014157:Transcription Factors / Q000378:metabolism; D051155:Wnt1 Protein / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D005819:Genetic Markers; D009687:Nuclear Proteins; D011987:Receptors, Steroid; D014157:Transcription Factors; D051155:Wnt1 Protein; C094295:svp protein, Drosophila; C074622:wg protein, Drosophila; C066591:abd-A protein, Drosophila
keywords: Abdominal-A; Aorta; Drosophila; Heart; Inflow tract; Ostia; Seven-up; Tinman; Wingless