title: Drosophila Lin-7 is a component of the Crumbs complex in epithelia and photoreceptor cells and prevents light-induced retinal degeneration.
abstract: The Drosophila Crumbs protein complex is required to maintain epithelial cell polarity in the embryo, to ensure proper morphogenesis of photoreceptor cells and to prevent light-dependent retinal degeneration. In Drosophila, the core components of the complex are the transmembrane protein Crumbs, the membrane-associated guanylate kinase (MAGUK) Stardust and the scaffolding protein DPATJ. The composition of the complex and some of its functions are conserved in mammalian epithelial and photoreceptor cells. Here, we report that Drosophila Lin-7, a scaffolding protein with one Lin-2/Lin-7 (L27) domain and one PSD-95/Dlg/ZO-1 (PDZ) domain, is associated with the Crumbs complex in the subapical region of embryonic and follicle epithelia and at the stalk membrane of adult photoreceptor cells. DLin-7 loss-of-function mutants are viable and fertile. While DLin-7 localization depends on Crumbs, neither Crumbs, Stardust nor DPATJ require DLin-7 for proper accumulation in the subapical region. Unlike other components of the Crumbs complex, DLin-7 is also enriched in the first optic ganglion, the lamina, where it co-localizes with Discs large, another member of the MAGUK family. In contrast to crumbs mutant photoreceptor cells, those mutant for DLin-7 do not display any morphogenetic abnormalities. Similar to crumbs mutant eyes, however, DLin-7 mutant photoreceptors undergo progressive, light-dependent degeneration. These results support the previous conclusions that the function of the Crumbs complex in cell survival is independent from its function in photoreceptor morphogenesis.
authors.affiliation: Institut für Genetik, Heinrich-Heine-Universität Düsseldorf, Universitätsstrasse 1, D-40225 Düsseldorf, Germany.
authors.forename: André
authors.initials: A
authors.lastname: Bachmann
authors.forename: Ferdi
authors.initials: F
authors.lastname: Grawe
authors.forename: Kevin
authors.initials: K
authors.lastname: Johnson
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Knust
mesh_terms: D000818:Animals; D015815:Cell Adhesion Molecules / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D002470:Cell Survival; D004330:Drosophila / Q000196:embryology / Q000235:genetics / Q000378:metabolism*; D029721:Drosophila Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D004848:Epithelium / Q000196:embryology / Q000378:metabolism; D005136:Eye Proteins / Q000378:metabolism; D051528:Guanylate Kinases; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000378:metabolism; D009024:Morphogenesis; D009154:Mutation; D009703:Nucleoside-Phosphate Kinase / Q000378:metabolism; D017956:Photoreceptor Cells, Invertebrate / Q000166:cytology / Q000196:embryology / Q000378:metabolism*; D012162:Retinal Degeneration / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D015815:Cell Adhesion Molecules; D029721:Drosophila Proteins; D005136:Eye Proteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; C501446:PATJ protein, Drosophila; C494546:Veli protein, Drosophila; C064360:crb protein, Drosophila; D009703:Nucleoside-Phosphate Kinase; D051528:Guanylate Kinases; C444479:sdt protein, Drosophila