title: Intracellular redirection of plasma membrane trafficking after loss of epithelial cell polarity.
abstract: In polarized Madin-Darby canine kidney epithelial cells, components of the plasma membrane fusion machinery, the t-SNAREs syntaxin 2, 3, and 4 and SNAP-23, are differentially localized at the apical and/or basolateral plasma membrane domains. Here we identify syntaxin 11 as a novel apical and basolateral plasma membrane t-SNARE. Surprisingly, all of these t-SNAREs redistribute to intracellular locations when Madin-Darby canine kidney cells lose their cellular polarity. Apical SNAREs relocalize to the previously characterized vacuolar apical compartment, whereas basolateral SNAREs redistribute to a novel organelle that appears to be the basolateral equivalent of the vacuolar apical compartment. Both intracellular plasma membrane compartments have an associated prominent actin cytoskeleton and receive membrane traffic from cognate apical or basolateral pathways, respectively. These findings demonstrate a fundamental shift in plasma membrane traffic toward intracellular compartments while protein sorting is preserved when epithelial cells lose their cell polarity.
authors.affiliation: Department of Cell Biology, Lerner Research Institute, Cleveland, Ohio 44195, USA.
authors.forename: S H
authors.initials: SH
authors.lastname: Low
authors.forename: M
authors.initials: M
authors.lastname: Miura
authors.forename: P A
authors.initials: PA
authors.lastname: Roche
authors.forename: A C
authors.initials: AC
authors.lastname: Valdez
authors.forename: K E
authors.initials: KE
authors.lastname: Mostov
authors.forename: T
authors.initials: T
authors.lastname: Weimbs
mesh_terms: D000818:Animals; D002118:Calcium / Q000502:physiology; D002460:Cell Line; D002462:Cell Membrane / Q000502:physiology* / Q000648:ultrastructure*; D016764:Cell Polarity; D004285:Dogs; D004847:Epithelial Cells / Q000502:physiology* / Q000648:ultrastructure*; D006801:Humans; D007668:Kidney; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D050765:Qa-SNARE Proteins; D011994:Recombinant Proteins / Q000378:metabolism; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D008565:Membrane Proteins; D050765:Qa-SNARE Proteins; D011994:Recombinant Proteins; D002118:Calcium