title: Syndecan contributes to heart cell specification and lumen formation during Drosophila cardiogenesis.
abstract: The transmembrane proteoglycan Syndecan contributes to cell surface signaling of diverse ligands in mammals, yet in Drosophila, genetic evidence links Syndecan only to the Slit receptor Roundabout and to the receptor tyrosine phosphatase LAR. Here we characterize the requirement for syndecan in the determination and morphogenesis of the Drosophila heart, and reveal two phases of activity, indicating that Syndecan is a co-factor in at least two signaling events in this tissue. There is a stochastic failure to determine heart cell progenitors in a subset of abdominal hemisegments in embryos mutant for syndecan, and subsequent to Syndecan depletion by RNA interference. This phenotype is sensitive to gene dosage in the FGF receptor (Heartless), its ligand, Pyramus, as well as BMP-ligand Decapentaplegic (Dpp) and co-factor Sara. Syndecan is also required for lumen formation during assembly of the heart vessel, a phenotype shared with mutations in the Slit and Integrin signaling pathways. Phenotypic interactions of syndecan with slit and Integrin mutants suggest intersecting function, consistent with Syndecan acting as a co-receptor for Slit in the Drosophila heart.
authors.affiliation: Department of Biology, McMaster University, 1280 Main St. W., Hamilton, Ontario, Canada.
authors.forename: Jessica
authors.initials: J
authors.lastname: Knox
authors.forename: Katherine
authors.initials: K
authors.lastname: Moyer
authors.forename: Nasrine
authors.initials: N
authors.lastname: Yacoub
authors.forename: Candice
authors.initials: C
authors.lastname: Soldaat
authors.forename: Martin
authors.initials: M
authors.lastname: Komosa
authors.forename: Katerina
authors.initials: K
authors.lastname: Vassilieva
authors.forename: Ronit
authors.initials: R
authors.lastname: Wilk
authors.forename: Jack
authors.initials: J
authors.lastname: Hu
authors.forename: Luz de Lourdes
authors.initials: Lde L
authors.lastname: Vazquez Paz
authors.forename: Qamber
authors.initials: Q
authors.lastname: Syed
authors.forename: Henry M
authors.initials: HM
authors.lastname: Krause
authors.forename: Mihaela
authors.initials: M
authors.lastname: Georgescu
authors.forename: J Roger
authors.initials: JR
authors.lastname: Jacobs
mesh_terms: D000818:Animals; D016764:Cell Polarity; D029721:Drosophila Proteins / Q000502:physiology; D004331:Drosophila melanogaster / Q000196:embryology*; D006321:Heart / Q000196:embryology*; D016023:Integrins / Q000502:physiology; D009024:Morphogenesis; D009419:Nerve Tissue Proteins / Q000502:physiology; D053667:Syndecans / Q000502:physiology*
chemical_list: D029721:Drosophila Proteins; D016023:Integrins; D009419:Nerve Tissue Proteins; D053667:Syndecans; C066819:sli protein, Drosophila