Annexin II Is Required for Apical Transport in Polarized Epithelial Cells*
- Ralf Jacobद,
- Martin Heine‡§,
- Jürgen Eikemeyer‡,
- Nadine Frerker‡,
- Klaus-Peter Zimmer∥,
- Ursula Rescher**,
- Volker Gerke** and
- Hassan Y. Naim‡
- ‡Department of Physiological Chemistry, School of Veterinary Medicine Hannover, ∥University Children's Hospital Muenster, **Institute for Medical Biochemistry, University of Muenster, §Department of Cell Biology and Cell Pathology, D-35033 Marburg, Germany
- ¶ To whom correspondence should be addressed: Dept. of Cell Biology and Cell Pathology, University of Marburg, Robert-Koch-Str. 6, D-35033 Marburg, Germany, Tel.: 49-6421-286-6482; Fax: 49-6421-286-6414; E-mail: jacob{at}staff.uni-marburg.de.
Abstract
The sorting of apical proteins comprises an initial recognition step in the trans Golgi network and a final partitioning of the apical pool of proteins into at least two different types of vesicular carriers. One criteria of these carriers is the association or non-association of the protein content with lipid rafts. We have previously characterized a population containing the raft-associated sucrase-isomaltase-carrying vesicles (SAVs) and another one, the non-raft-associated lactase-phlorizin hydrolase-carrrying vesicles (LAVs) that are targeted separately to the apical membrane. Here, we demonstrate biochemically and by employing confocal laser microscopy that the annexin II-S100A10 complex is a component of SAVs and is absent from LAVs. The unequivocal role of annexin II in the apical targeting of SI is clearly demonstrated when down-regulation of this protein by annexin II-specific small interfering RNA drastically decreases the apical delivery of SI in the epithelial cell line Madin-Darby canine kidney. The annexin II-S100A10 complex plays therefore a crucial role in routing SAVs to the apical membrane of epithelial cells.
Footnotes
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↵1 The abbreviations used are: TGN, trans Golgi network; SI, sucraseisomaltase (all forms); LPH, lactase-phlorizin hydrolase; SAV, SIcarrying apical vesicle; LAV, LPH-carrying apical vesicle; DMEM, Dulbecco's modified Eagle's medium; TEMED, N,N,N′,N′-tetramethylenediamine; RNAi, RNA-mediated interference; MDCK, Madin-Darby canine kidney; mAb, monoclonal antibody; CFP, cyan fluorescent protein; YFP, yellow fluorescent protein.
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↵* This work was supported by the Deutsche Forschungsgemeinschaft, Bonn, Germany (Grant JA 1033/1-2) and by the Sonderforschungsbereich 621, Bonn, Germany (to H. Y. N. and R. J.). The costs of publication of this article were defrayed in part by the payment of page charges. This 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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- Received November 20, 2003.
- Revision received December 9, 2003.
- The American Society for Biochemistry and Molecular Biology, Inc.
