title: N-Glycosylation instead of cholesterol mediates oligomerization and apical sorting of GPI-APs in FRT cells.
abstract: Sorting of glycosylphosphatidyl-inositol--anchored proteins (GPI-APs) in polarized epithelial cells is not fully understood. Oligomerization in the Golgi complex has emerged as the crucial event driving apical segregation of GPI-APs in two different kind of epithelial cells, Madin-Darby canine kidney (MDCK) and Fisher rat thyroid (FRT) cells, but whether the mechanism is conserved is unknown. In MDCK cells cholesterol promotes GPI-AP oligomerization, as well as apical sorting of GPI-APs. Here we show that FRT cells lack this cholesterol-driven oligomerization as apical sorting mechanism. In these cells both apical and basolateral GPI-APs display restricted diffusion in the Golgi likely due to a cholesterol-enriched membrane environment. It is striking that N-glycosylation is the critical event for oligomerization and apical sorting of GPI-APs in FRT cells but not in MDCK cells. Our data indicate that at least two mechanisms exist to determine oligomerization in the Golgi leading to apical sorting of GPI-APs. One depends on cholesterol, and the other depends on N-glycosylation and is insensitive to cholesterol addition or depletion.
authors: Institut Pasteur, Unité de Traffic Membranaire et Pathogenèse, 75015 Paris, France.
authors: Naga Salaija
authors: NS
authors: Imjeti
authors: Stéphanie
authors: S
authors: Lebreton
authors: Simona
authors: S
authors: Paladino
authors: Erwin
authors: E
authors: de la Fuente
authors: Alfonso
authors: A
authors: Gonzalez
authors: Chiara
authors: C
authors: Zurzolo
mesh_terms: D000818:Animals; D016764:Cell Polarity; D002478:Cells, Cultured; D002784:Cholesterol / Q000378:metabolism* / Q000494:pharmacology; D004285:Dogs; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D036681:Fluorescence Recovery After Photobleaching; D058851:GPI-Linked Proteins / Q000235:genetics / Q000378:metabolism*; D006031:Glycosylation; D006056:Golgi Apparatus / Q000378:metabolism / Q000648:ultrastructure; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D007668:Kidney / Q000166:cytology; D021381:Protein Transport; D051381:Rats; D011916:Rats, Inbred F344; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013961:Thyroid Gland / Q000166:cytology / Q000378:metabolism
chemical_list: D058851:GPI-Linked Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D002784:Cholesterol