title: The positioning and segregation of apical cues during epithelial polarity establishment in Drosophila.
abstract: Cell polarity is critical for epithelial structure and function. Adherens junctions (AJs) often direct this polarity, but we previously found that Bazooka (Baz) acts upstream of AJs as epithelial polarity is first established in Drosophila. This prompted us to ask how Baz is positioned and how downstream polarity is elaborated. Surprisingly, we found that Baz localizes to an apical domain below its typical binding partners atypical protein kinase C (aPKC) and partitioning defective (PAR)-6 as the Drosophila epithelium first forms. In fact, Baz positioning is independent of aPKC and PAR-6 relying instead on cytoskeletal cues, including an apical scaffold and dynein-mediated basal-to-apical transport. AJ assembly is closely coupled to Baz positioning, whereas aPKC and PAR-6 are positioned separately. This forms a stratified apical domain with Baz and AJs localizing basal to aPKC and PAR-6, and we identify specific mechanisms that keep these proteins apart. These results reveal key steps in the assembly of the apical domain in Drosophila.
authors.affiliation: Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA. tonyh@email.unc.edu
authors.forename: Tony J C
authors.initials: TJ
authors.lastname: Harris
authors.forename: Mark
authors.initials: M
authors.lastname: Peifer
mesh_terms: D000199:Actins / Q000378:metabolism; D022005:Adherens Junctions / Q000378:metabolism; D000818:Animals; D019521:Body Patterning; D003599:Cytoskeleton / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000033:anatomy & histology / Q000196:embryology; D004398:Dyneins / Q000378:metabolism; D004847:Epithelial Cells / Q000166:cytology* / Q000502:physiology*; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D008870:Microtubules / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism; D021381:Protein Transport / Q000502:physiology; D011506:Proteins / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D000199:Actins; D029721:Drosophila Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D011506:Proteins; D011993:Recombinant Fusion Proteins; C400774:baz protein, Drosophila; C064360:crb protein, Drosophila; C115015:PKC-3 protein; D011493:Protein Kinase C; D004398:Dyneins