Rab14 regulation of claudin-2 trafficking modulates epithelial permeability and lumen morphogenesis.
Regulation of epithelial barrier function requires targeted insertion of tight junction proteins that have distinct selectively permeable characteristics. The insertion of newly synthesized proteins and recycling of internalized tight junction components control both polarity and junction function. Here we show that the small GTPase Rab14 regulates tight junction structure. In Madin-Darby canine kidney (MDCK) II cells, Rab14 colocalizes with junctional proteins, and knockdown of Rab14 results in increased transepithelial resistance. In cells without Rab14, there are small changes in the trafficking of claudin-1 and occludin. In addition, there is substantial depletion of the leaky claudin, claudin-2, but not other tight junction components. The loss of claudin-2 is complemented by inhibition of lysosomal function, suggesting that Rab14 sorts claudin-2 out of the lysosome-directed pathway. MDCK I cells lack claudin-2 endogenously, and knockdown of Rab14 in these cells does not result in a change in transepithelial resistance, suggesting that the effect is specific to claudin-2 trafficking. Furthermore, leaky claudins have been shown to be required for epithelial morphogenesis, and knockdown of Rab14 results in failure to form normal single-lumen cysts in three-dimensional culture. These results implicate Rab14 in specialized trafficking of claudin-2 from the recycling endosome.
Department of Cellular and Molecular Medicine, University of Arizona College of Medicine, Tucson, AZ 85724.
Ruifeng
R
Lu
Department of Cellular and Molecular Medicine, University of Arizona College of Medicine, Tucson, AZ 85724.
Debra L
DL
Johnson
Department of Cellular and Molecular Medicine, University of Arizona College of Medicine, Tucson, AZ 85724.
Lorraine
L
Stewart
Department of Cellular and Molecular Medicine, University of Arizona College of Medicine, Tucson, AZ 85724.
Kelsey
K
Waite
Department of Cellular and Molecular Medicine, University of Arizona College of Medicine, Tucson, AZ 85724.
David
D
Elliott
Department of Cellular and Molecular Medicine, University of Arizona College of Medicine, Tucson, AZ 85724 jeanw@email.arizona.edu.
Jean M
JM
Wilson
D000643:Ammonium Chloride / Q000494:pharmacology; D000818:Animals; D019921:Biotinylation / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D002463:Cell Membrane Permeability / Q000187:drug effects; D062446:Claudin-2 / Q000378:metabolism*; D004285:Dogs; D017097:Electric Impedance; D004705:Endocytosis / Q000187:drug effects; D004847:Epithelial Cells / Q000166:cytology* / Q000378:metabolism*; D055785:Gene Knockdown Techniques; D006801:Humans; D061985:Madin Darby Canine Kidney Cells; D009024:Morphogenesis / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D034741:RNA, Small Interfering / Q000378:metabolism; D019108:Tight Junctions / Q000187:drug effects / Q000378:metabolism; D020691:rab GTP-Binding Proteins / Q000378:metabolism*
D062446:Claudin-2; D034741:RNA, Small Interfering; D000643:Ammonium Chloride; D020691:rab GTP-Binding Proteins; D002118:Calcium