title: pH-dependent recycling of galectin-3 at the apical membrane of epithelial cells.
abstract: The β-galactoside binding protein galectin-3 is highly expressed in a variety of epithelial cell lines. Polarized MDCK cells secrete this lectin predominantly into the apical medium by non-classical secretion. Once within the apical extracellular milieu, galectin-3 can re-enter the cell followed by passage through endosomal organelles and modulate apical protein sorting. Here, we could show that galectin-3 is internalized by non-clathrin mediated endocytosis. Within endosomal organelles this pool associates with newly synthesized neurotrophin receptor in the biosynthetic pathway and assists in its membrane targeting. This recycling process is accompanied by transient interaction of galectin-3 with detergent insoluble membrane microdomains in a lactose- and pH-dependent manner. Moreover, in the presence of lactose, apical sorting of the neurotrophin receptor is affected following endosomal deacidification. Taken together, our results suggest that internalized galectin-3 directs the subcellular targeting of apical glycoproteins by membrane recycling.
authors.affiliation: Department of Cell Biology and Cell Pathology, Philipps-Universität Marburg, D-35033, Marburg, Germany.
authors.forename: Tamara
authors.initials: T
authors.lastname: Straube
authors.forename: Tobias
authors.initials: T
authors.lastname: von Mach
authors.forename: Ellena
authors.initials: E
authors.lastname: Hönig
authors.forename: Christoph
authors.initials: C
authors.lastname: Greb
authors.forename: Dominik
authors.initials: D
authors.lastname: Schneider
authors.forename: Ralf
authors.initials: R
authors.lastname: Jacob
mesh_terms: D000818:Animals; D001692:Biological Transport; D022461:Caveolins / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D016764:Cell Polarity / Q000502:physiology; D002966:Clathrin / Q000378:metabolism; D004285:Dogs; D004705:Endocytosis / Q000502:physiology*; D011992:Endosomes / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism*; D037502:Galectin 3 / Q000378:metabolism*; D006023:Glycoproteins / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007785:Lactose / Q000378:metabolism; D061985:Madin Darby Canine Kidney Cells; D021962:Membrane Microdomains / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D021381:Protein Transport; D017475:Receptors, Nerve Growth Factor / Q000378:metabolism
chemical_list: D022461:Caveolins; D002966:Clathrin; D037502:Galectin 3; D006023:Glycoproteins; D008565:Membrane Proteins; D017475:Receptors, Nerve Growth Factor; C106354:flotillins; D007785:Lactose
keywords: MDCK; apical sorting; endosomes; galectin-3; neurotrophin receptor; protein trafficking