title: Galectin-4-regulated delivery of glycoproteins to the brush border membrane of enterocyte-like cells.
abstract: We have previously reported that silencing of galectin-4 expression in polarized HT-29 cells perturbed apical biosynthetic trafficking and resulted in a phenotype similar to the inhibitor of glycosylation, 1-benzyl-2-acetamido-2-deoxy-beta-d-galactopyranoside (GalNAcalpha-O-bn). We now present evidence of a lipid raft-based galectin-4-dependent mechanism of apical delivery of glycoproteins in these cells. First, galectin-4 recruits the apical glycoproteins in detergent-resistant membranes (DRMs) because these glycoproteins were depleted in DRMs isolated from galectin-4-knockdown (KD) HT-29 5M12 cells. DRM-associated glycoproteins were identified as ligands for galectin-4. Structural analysis showed that DRMs were markedly enriched in a series of complex N-glycans in comparison to detergent-soluble membranes. Second, in galectin-4-KD cells, the apical glycoproteins still exit the Golgi but accumulated inside the cells, showing that their recruitment within lipid rafts and their apical trafficking required the delivery of galectin-4 at a post-Golgi level. This lectin that is synthesized on free cytoplasmic ribosomes is externalized from HT-29 cells mostly in the apical medium and follows an apical endocytic-recycling pathway that is required for the apical biosynthetic pathway. Together, our data show that the pattern of N-glycosylation of glycoproteins serves as a recognition signal for endocytosed galectin-4, which drives the raft-dependent apical pathway of glycoproteins in enterocyte-like HT-29 cells.
authors.affiliation: Centre de Recherche Jean-Pierre Aubert, Unité INSERM U837, Faculté de Médecine, Lille, France.
authors.forename: Laurence
authors.initials: L
authors.lastname: Stechly
authors.forename: Willy
authors.initials: W
authors.lastname: Morelle
authors.forename: Anne-Frédérique
authors.initials: AF
authors.lastname: Dessein
authors.forename: Sabine
authors.initials: S
authors.lastname: André
authors.forename: Georges
authors.initials: G
authors.lastname: Grard
authors.forename: Dave
authors.initials: D
authors.lastname: Trinel
authors.forename: Marie-José
authors.initials: MJ
authors.lastname: Dejonghe
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Leteurtre
authors.forename: Hervé
authors.initials: H
authors.lastname: Drobecq
authors.forename: Germain
authors.initials: G
authors.lastname: Trugnan
authors.forename: Hans Joachim
authors.initials: HJ
authors.lastname: Gabius
authors.forename: Guillemette
authors.initials: G
authors.lastname: Huet
mesh_terms: D015415:Biomarkers / Q000378:metabolism; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D002462:Cell Membrane / Q000378:metabolism*; D016764:Cell Polarity; D018819:Dipeptidyl Peptidase 4 / Q000235:genetics / Q000378:metabolism; D020895:Enterocytes / Q000166:cytology* / Q000378:metabolism; D037541:Galectin 4 / Q000378:metabolism*; D006023:Glycoproteins / Q000737:chemistry / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism; D019073:HT29 Cells; D006801:Humans; D021962:Membrane Microdomains / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D015415:Biomarkers; D037541:Galectin 4; D006023:Glycoproteins; D011993:Recombinant Fusion Proteins; C042807:DPP4 protein, human; D018819:Dipeptidyl Peptidase 4