title: Drosophila PAR-1 and 14-3-3 inhibit Bazooka/PAR-3 to establish complementary cortical domains in polarized cells.
abstract: PAR-1 kinases are required for polarity in diverse cell types, such as epithelial cells, where they localize laterally. PAR-1 activity is believed to be transduced by binding of 14-3-3 proteins to its phosphorylated substrates, but the relevant targets are unknown. We show that PAR-1 phosphorylates Bazooka/PAR-3 on two conserved serines to generate 14-3-3 binding sites. This inhibits formation of the Bazooka/PAR-6/aPKC complex by blocking Bazooka oligomerization and binding to aPKC. In epithelia, this complex localizes apically and defines the apical membrane, whereas Bazooka lacking PAR-1 phosphorylation/14-3-3 binding sites forms ectopic lateral complexes. Lateral exclusion by PAR-1/14-3-3 cooperates with apical anchoring by Crumbs/Stardust to restrict Bazooka localization, and loss of both pathways disrupts epithelial polarity. PAR-1 also excludes Bazooka from the posterior of the oocyte, and disruption of this regulation causes anterior-posterior polarity defects. Thus, antagonism of Bazooka by PAR-1/14-3-3 may represent a general mechanism for establishing complementary cortical domains in polarized cells.
authors.affiliation: The Wellcome Trust/Cancer Research UK Institute and Department of Genetics, University of Cambridge, CB2 1QR Cambridge, United Kingdom.
authors.forename: Richard
authors.initials: R
authors.lastname: Benton
authors.forename: Daniel
authors.initials: D
authors.lastname: St Johnston
mesh_terms: D048948:14-3-3 Proteins; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D019521:Body Patterning / Q000235:genetics; D002352:Carrier Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation / Q000235:genetics; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism; D016764:Cell Polarity / Q000502:physiology*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000196:embryology* / Q000235:genetics / Q000378:metabolism; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism*; D038362:Glycogen Synthase Kinase 3; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D009865:Oocytes / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding / Q000235:genetics; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D014446:Tyrosine 3-Monooxygenase / Q000235:genetics / Q000378:metabolism*
chemical_list: D048948:14-3-3 Proteins; D002352:Carrier Proteins; D029721:Drosophila Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; C400774:baz protein, Drosophila; C064360:crb protein, Drosophila; D014446:Tyrosine 3-Monooxygenase; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; C115015:PKC-3 protein; D011493:Protein Kinase C; D038362:Glycogen Synthase Kinase 3; C472496:Par-1 protein, Drosophila