Rab17 Localizes to Recycling Endosomes and Regulates Receptor-mediated Transcytosis in Epithelial Cells*
- From the Institute of Biochemistry, University of Lausanne, CH-1066 Epalinges, Switzerland and the §Department of Cell Biology, University of Utrecht, 3584 CX Utrecht, The Netherlands
Abstract
The small GTPase Rab17 is restricted to epithelial cells and its expression is induced during cell polarization. This observation has led to the suggestion that the protein may function in transcytosis, a pathway connecting the apical and basolateral endocytic systems. To analyze whether Rab17 plays a role in transcellular transport, we generated Madin-Darby canine kidney (MDCK) cell lines stably coexpressing wild-type or mutant Rab17 and the transcytotic polymeric immunoglobulin receptor (pIgR). Rab17 expressed in MDCK cells was found on small vesicles and tubules in the apical region of the cells. A significant fraction of the Rab17-positive structures was accessible to dimeric IgA internalized from the apical or basolateral cell surface via the pIgR. Furthermore, basolateral to apical transcytosis of dimeric IgA was impaired in MDCK cells overexpressing Rab17. Our data provides morphological and biochemical evidence for a role of Rab17 in the regulation of transcellular traffic through apical recycling endosomes in epithelial cells.
Footnotes
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↵* This project was supported by a grant and a career development (START) award from the Swiss National Science Foundation (to W. H.) and Grant RUU 95-1073 from the Dutch Cancer Society (to P. J. P.).The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵‡ To whom correspondence should be addressed: Institute of Biochemistry, University of Lausanne, Ch. des Boveresses 155, CH-1066 Epalinges, Switzerland. Tel.: 41-21-692-57-37; Fax: 41-21-692-57-05; E-mail: Walter.Hunziker{at}ib.unil.ch.
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↵1 The abbreviations used are: TGN,trans-Golgi network; dIgA, dimeric IgA; pIgR, polymeric immunoglobulin receptor; TfR, transferrin receptor; MDCK, Madin-Darby canine kidney; PCR, polymerase chain reaction; PBS, phosphate-buffered saline; PAGE, polyacrylamide gel electrophoresis.
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↵2 W. Hunziker, unpublished observations.
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↵3 M. Zerial, personal communication.
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↵4 G. van Meer, K. Sandvig, and W. Hunziker, unpublished results.
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- Received December 19, 1997.
- Revision received March 26, 1998.
- The American Society for Biochemistry and Molecular Biology, Inc.
