title: Rab14 regulates apical targeting in polarized epithelial cells.
abstract: Epithelial cells display distinct apical and basolateral membrane domains, and maintenance of this asymmetry is essential to the function of epithelial tissues. Polarized delivery of apical and basolateral membrane proteins from the trans Golgi network (TGN) and/or endosomes to the correct domain requires specific cytoplasmic machinery to control the sorting, budding and fission of vesicles. However, the molecular machinery that regulates polarized delivery of apical proteins remains poorly understood. In this study, we show that the small guanosine triphosphatase Rab14 is involved in the apical targeting pathway. Using yeast two-hybrid analysis and glutathione S-transferase pull down, we show that Rab14 interacts with apical membrane proteins and localizes to the TGN and apical endosomes. Overexpression of the GDP mutant form of Rab14 (S25N) induces an enlargement of the TGN and vesicle accumulation around Golgi membranes. Moreover, expression of Rab14-S25N results in mislocalization of the apical raft-associated protein vasoactive intestinal peptide/MAL to the basolateral domain but does not disrupt basolateral targeting or recycling. These data suggest that Rab14 specifically regulates delivery of cargo from the TGN to the apical domain.
authors.affiliation: Department of Cell Biology and Anatomy, Arizona Health Sciences Center, University of Arizona, PO Box 245044, Tucson, AZ 85724, USA.
authors.forename: Khameeka N
authors.initials: KN
authors.lastname: Kitt
authors.forename: Delia
authors.initials: D
authors.lastname: Hernández-Deviez
authors.forename: Sarah D
authors.initials: SD
authors.lastname: Ballantyne
authors.forename: Elias T
authors.initials: ET
authors.lastname: Spiliotis
authors.forename: James E
authors.initials: JE
authors.lastname: Casanova
authors.forename: Jean M
authors.initials: JM
authors.lastname: Wilson
mesh_terms: D000818:Animals; D002460:Cell Line; D003593:Cytoplasm / Q000378:metabolism; D004285:Dogs; D011992:Endosomes / Q000378:metabolism; D004847:Epithelial Cells / Q000166:cytology*; D020558:GTP Phosphohydrolases / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism; D009154:Mutation; D021381:Protein Transport; D051381:Rats; D020798:Two-Hybrid System Techniques; D020691:rab GTP-Binding Proteins / Q000378:metabolism / Q000502:physiology*
chemical_list: D005982:Glutathione Transferase; D020558:GTP Phosphohydrolases; C494592:Rab14 protein, rat; D020691:rab GTP-Binding Proteins