title: Cdc42 and Par proteins stabilize dynamic adherens junctions in the Drosophila neuroectoderm through regulation of apical endocytosis.
abstract: Cell rearrangements require dynamic changes in cell-cell contacts to maintain tissue integrity. We investigated the function of Cdc42 in maintaining adherens junctions (AJs) and apical polarity in the Drosophila melanogaster neuroectodermal epithelium. About one third of cells exit the epithelium through ingression and become neuroblasts. Cdc42-compromised embryos lost AJs in the neuroectoderm during neuroblast ingression. In contrast, when neuroblast formation was suppressed, AJs were maintained despite the loss of Cdc42 function. Loss of Cdc42 function caused an increase in the endocytotic uptake of apical proteins, including apical polarity factors such as Crumbs, which are required for AJ stability. In addition, Cdc42 has a second function in regulating endocytotic trafficking, as it is required for the progression of apical cargo from the early to the late endosome. The Par complex acts as an effector for Cdc42 in controlling the endocytosis of apical proteins. This study reveals functional interactions between apical polarity proteins and endocytosis that are critical for stabilizing dynamic basolateral AJs.
authors.affiliation: Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada.
authors.forename: Kathryn P
authors.initials: KP
authors.lastname: Harris
authors.forename: Ulrich
authors.initials: U
authors.lastname: Tepass
mesh_terms: D022005:Adherens Junctions / Q000201:enzymology*; D000818:Animals; D016764:Cell Polarity; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000166:cytology / Q000196:embryology / Q000201:enzymology*; D004625:Embryo, Nonmammalian / Q000002:abnormalities / Q000201:enzymology; D004705:Endocytosis; D004789:Enzyme Activation; D004848:Epithelium / Q000201:enzymology; D019204:GTP-Binding Proteins / Q000378:metabolism*; D005799:Genes, Dominant; D008565:Membrane Proteins / Q000378:metabolism; D008954:Models, Biological; D046912:Multiprotein Complexes / Q000378:metabolism; D054258:Neural Plate / Q000166:cytology* / Q000201:enzymology; D010641:Phenotype; D011493:Protein Kinase C / Q000378:metabolism; D021381:Protein Transport; D011726:Pyridinium Compounds / Q000378:metabolism; D000644:Quaternary Ammonium Compounds / Q000378:metabolism
chemical_list: C090145:Cdc42 protein, Drosophila; D029721:Drosophila Proteins; C092350:FM 4-64; D008565:Membrane Proteins; D046912:Multiprotein Complexes; D011726:Pyridinium Compounds; D000644:Quaternary Ammonium Compounds; C115015:PKC-3 protein; D011493:Protein Kinase C; D019204:GTP-Binding Proteins