title: Apical sorting by galectin-3-dependent glycoprotein clustering.
abstract: Epithelial cells are characterized by their polarized organization based on an apical membrane that is separated from the basolateral membrane domain by tight junctions. Maintenance of this morphology is guaranteed by highly specific sorting machinery that separates lipids and proteins into different carrier populations for the apical or basolateral cell surface. Lipid-raft-independent apical carrier vesicles harbour the beta-galactoside-binding lectin galectin-3, which interacts directly with apical cargo in a glycan-dependent manner. These glycoproteins are mistargeted to the basolateral membrane in galectin-3-depleted cells, dedicating a central role to this lectin in raft-independent sorting as apical receptor. Here, we demonstrate that high-molecular-weight clusters are exclusively formed in the presence of galectin-3. Their stability is sensitive to increased carbohydrate concentrations, and cluster formation as well as apical sorting are perturbed in glycosylation-deficient Madin-Darby canine kidney (MDCK) II cells. Together, our data suggest that glycoprotein cross-linking by galectin-3 is required for apical sorting of non-raft-associated cargo.
authors.affiliation: Department of Cell Biology and Cell Pathology, Philipps-Universität Marburg, 35033 Marburg, Germany.
authors.forename: Delphine
authors.initials: D
authors.lastname: Delacour
authors.forename: Christoph
authors.initials: C
authors.lastname: Greb
authors.forename: Annett
authors.initials: A
authors.lastname: Koch
authors.forename: Emma
authors.initials: E
authors.lastname: Salomonsson
authors.forename: Hakon
authors.initials: H
authors.lastname: Leffler
authors.forename: Andre
authors.initials: A
authors.lastname: Le Bivic
authors.forename: Ralf
authors.initials: R
authors.lastname: Jacob
mesh_terms: D000818:Animals; D002460:Cell Line; D004285:Dogs; D037502:Galectin 3 / Q000502:physiology*; D006023:Glycoproteins / Q000378:metabolism*; D006031:Glycosylation; D021381:Protein Transport; D020800:Receptor, Nerve Growth Factor / Q000235:genetics / Q000378:metabolism
chemical_list: D037502:Galectin 3; D006023:Glycoproteins; D020800:Receptor, Nerve Growth Factor