title: Par-1 kinase establishes cell polarity and functions in Notch signaling in the Drosophila embryo.
abstract: The Drosophila protein kinase Par-1 is expressed throughout Drosophila development, but its function has not been extensively characterized because of oocyte lethality of null mutants. In this report, we have characterized the function of Par-1 in embryonic and post-embryonic epithelia. Par-1 protein is dynamically localized during embryonic cell polarization, transiently restricted to the lateral membrane domain, followed by apicolateral localization. We depleted maternal and zygotic par-1 by RNAi and revealed a requirement for Par-1 in establishing cell polarity. Par-1 restricts the coalescing adherens junction to an apicolateral position and prevents its widespread formation along the lateral domain. Par-1 also promotes the localization of lateral membrane proteins such as Delta. These activities are important for the further development of cell polarity during gastrulation. By contrast, Par-1 is not essential to maintain epithelial polarity once it has been established. However, it still has a maintenance role since overexpression causes severe polarity disruption. Additionally, we find a novel role for Par-1 in Notch signal transduction during embryonic neurogenesis and retina determination. Epistasis analysis indicates that Par-1 functions upstream of Notch and is critical for proper localization of the Notch ligand Delta.
authors.affiliation: Department of Biochemistry, Molecular Biology and Cell Biology, 2205 Tech Drive, Northwestern University, Evanston, IL 60208, USA.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Bayraktar
authors.forename: Deborah
authors.initials: D
authors.lastname: Zygmunt
authors.forename: Richard W
authors.initials: RW
authors.lastname: Carthew
mesh_terms: D000818:Animals; D016764:Cell Polarity; D004330:Drosophila / Q000196:embryology / Q000378:metabolism*; D029721:Drosophila Proteins / Q000378:metabolism*; D004625:Embryo, Nonmammalian / Q000378:metabolism; D038362:Glycogen Synthase Kinase 3; D008024:Ligands; D011494:Protein Kinases / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D051880:Receptors, Notch / Q000378:metabolism*; D012160:Retina / Q000196:embryology; D015398:Signal Transduction
chemical_list: D029721:Drosophila Proteins; D008024:Ligands; C497759:N protein, Drosophila; D051880:Receptors, Notch; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D038362:Glycogen Synthase Kinase 3; C472496:Par-1 protein, Drosophila