title: Echinoid regulates tracheal morphology and fusion cell fate in Drosophila.
abstract: Morphogenesis of the Drosophila embryonic trachea involves a stereotyped pattern of epithelial tube branching and fusion. Here, we report unexpected phenotypes resulting from maternal and zygotic (M/Z) loss of the homophilic cell adhesion molecule Echinoid (Ed), as well as the subcellular localization of Ed in the trachea. ed(M/Z) embryos have convoluted trachea reminiscent of septate junction (SJ) and luminal matrix mutants. However, Ed does not localize to SJs, and ed(M/Z) embryos have intact SJs and show normal luminal accumulation of the matrix-modifying protein Vermiform. Surprisingly, tracheal length is not increased in ed(M/Z) mutants, but a previously undescribed combination of reduced intersegmental spacing and deep epidermal grooves produces a convoluted tracheal phenotype. In addition, ed(M/Z) mutants have unique fusion defects involving supernumerary fusion cells, ectopic fusion events and atypical branch breaks. Tracheal-specific expression of Ed rescues these fusion defects, indicating that Ed acts in trachea to control fusion cell fate.
authors: Department of Biology, McGill University, Montréal, QC, Canada.
authors: Caroline
authors: C
authors: Laplante
authors: Sarah M
authors: SM
authors: Paul
authors: Greg J
authors: GJ
authors: Beitel
authors: Laura A
authors: LA
authors: Nilson
mesh_terms: D000581:Amidohydrolases / Q000235:genetics / Q000378:metabolism; D000818:Animals; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism*; D002459:Cell Fusion; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000033:anatomy & histology / Q000196:embryology; D004625:Embryo, Nonmammalian / Q000033:anatomy & histology / Q000502:physiology; D009024:Morphogenesis / Q000502:physiology*; D010641:Phenotype; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D014132:Trachea / Q000033:anatomy & histology / Q000196:embryology; D051155:Wnt1 Protein / Q000378:metabolism
chemical_list: D015815:Cell Adhesion Molecules; D029721:Drosophila Proteins; C422623:ED protein, Drosophila; D012097:Repressor Proteins; D051155:Wnt1 Protein; C064196:dpp protein, Drosophila; C074622:wg protein, Drosophila; D000581:Amidohydrolases; C509514:verm protein, Drosophila