Annexin II is required for apical transport in polarized epithelial cells.
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.
Jacob
Ralf
R
Department of Physiological Chemistry, School of Veterinary Medicine Hannover, Germany. jacob@staff.uni-marburg.de
Heine
Martin
M
Eikemeyer
Jürgen
J
Frerker
Nadine
N
Zimmer
Klaus-Peter
KP
Rescher
Ursula
U
Gerke
Volker
V
Naim
Hassan Y
HY
D000818:Animals; D017306:Annexin A2 / Q000737:chemistry / Q000502:physiology*; D019556:COS Cells; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism; D004285:Dogs; D015536:Down-Regulation; D004847:Epithelial Cells / Q000473:pathology*; D005089:Exocytosis; D020868:Gene Silencing; D006056:Golgi Apparatus / Q000378:metabolism; D015151:Immunoblotting; D010694:Lactase-Phlorizin Hydrolase / Q000737:chemistry; D013058:Mass Spectrometry; D021962:Membrane Microdomains / Q000378:metabolism; D018613:Microscopy, Confocal; D011233:Precipitin Tests; D034741:RNA, Small Interfering / Q000737:chemistry / Q000378:metabolism; D013997:Time Factors; D021601:trans-Golgi Network / Q000378:metabolism
D017306:Annexin A2; D034741:RNA, Small Interfering; D010694:Lactase-Phlorizin Hydrolase