title: v-SNARE cellubrevin is required for basolateral sorting of AP-1B-dependent cargo in polarized epithelial cells.
abstract: The epithelial cell-specific adaptor complex AP-1B is crucial for correct delivery of many transmembrane proteins from recycling endosomes to the basolateral plasma membrane. Subsequently, membrane fusion is dependent on the formation of complexes between SNARE proteins located at the target membrane and on transport vesicles. Although the t-SNARE syntaxin 4 has been localized to the basolateral membrane, the v-SNARE operative in the AP-1B pathway remained unknown. We show that the ubiquitously expressed v-SNARE cellubrevin localizes to the basolateral membrane and to recycling endosomes, where it colocalizes with AP-1B. Furthermore, we demonstrate that cellubrevin coimmunoprecipitates preferentially with syntaxin 4, implicating this v-SNARE in basolateral fusion events. Cleavage of cellubrevin with tetanus neurotoxin (TeNT) results in scattering of AP-1B localization and missorting of AP-1B-dependent cargos, such as transferrin receptor and a truncated low-density lipoprotein receptor, LDLR-CT27. These data suggest that cellubrevin and AP-1B cooperate in basolateral membrane trafficking.
authors.affiliation: Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, Evanston, IL 60208, USA.
authors.forename: Ian C
authors.initials: IC
authors.lastname: Fields
authors.forename: Elina
authors.initials: E
authors.lastname: Shteyn
authors.forename: Marc
authors.initials: M
authors.lastname: Pypaert
authors.forename: Véronique
authors.initials: V
authors.lastname: Proux-Gillardeaux
authors.forename: Richard S
authors.initials: RS
authors.lastname: Kang
authors.forename: Thierry
authors.initials: T
authors.lastname: Galli
authors.forename: Heike
authors.initials: H
authors.lastname: Fölsch
mesh_terms: D033961:Adaptor Protein Complex 1 / Q000235:genetics / Q000378:metabolism*; D033966:Adaptor Protein Complex beta Subunits / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D016764:Cell Polarity / Q000187:drug effects / Q000502:physiology*; D004285:Dogs; D011992:Endosomes / Q000378:metabolism*; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D008561:Membrane Fusion / Q000187:drug effects / Q000502:physiology; D008666:Metalloendopeptidases / Q000494:pharmacology; D021381:Protein Transport / Q000187:drug effects / Q000502:physiology; D050765:Qa-SNARE Proteins / Q000235:genetics / Q000378:metabolism; D011973:Receptors, LDL / Q000378:metabolism; D050600:SNARE Proteins / Q000235:genetics / Q000378:metabolism*; D013744:Tetanus Toxin / Q000494:pharmacology; D051040:Vesicle-Associated Membrane Protein 3 / Q000235:genetics / Q000378:metabolism*
chemical_list: C439126:AP1B1 protein, human; D033961:Adaptor Protein Complex 1; D033966:Adaptor Protein Complex beta Subunits; D050765:Qa-SNARE Proteins; D011973:Receptors, LDL; D050600:SNARE Proteins; D013744:Tetanus Toxin; C494946:VAMP3 protein, human; D051040:Vesicle-Associated Membrane Protein 3; C035979:tetanospasmin; D008666:Metalloendopeptidases