title: Functionally different pools of Shiga toxin receptor, globotriaosyl ceramide, in HeLa cells.
abstract: Many studies have investigated the intracellular trafficking of Shiga toxin, but very little is known about the underlying dynamics of its cellular receptor, the glycosphingolipid globotriaosyl ceramide. In this study, we show that globotriaosyl ceramide is required not only for Shiga toxin binding to cells, but also for its intracellular trafficking. Shiga toxin induces globotriaosyl ceramide recruitment to detergent-resistant membranes, and subsequent internalization of the lipid. The globotriaosyl ceramide pool at the plasma membrane is then replenished from internal stores. Whereas endocytosis is not affected in the recovery condition, retrograde transport of Shiga toxin to the Golgi apparatus and the endoplasmic reticulum is strongly inhibited. This effect is specific, as cholera toxin trafficking on GM(1) and protein biosynthesis are not impaired. The differential behavior of both toxins is also paralleled by the selective loss of Shiga toxin association with detergent-resistant membranes in the recovery condition, and comparison of the molecular species composition of plasma membrane globotriaosyl ceramide indicates subtle changes in favor of unsaturated fatty acids. In conclusion, this study demonstrates the dynamic behavior of globotriaosyl ceramide at the plasma membrane and suggests that globotriaosyl ceramide-specific determinants, possibly its molecular species composition, are selectively required for efficient retrograde sorting on endosomes, but not for endocytosis.
authors.affiliation: Laboratoire Trafic et Signalisation, Unité Mixte de Recherche 144, Institut Curie/CNRS, Paris, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Falguières
authors.forename: Winfried
authors.initials: W
authors.lastname: Römer
authors.forename: Mohamed
authors.initials: M
authors.lastname: Amessou
authors.forename: Carlos
authors.initials: C
authors.lastname: Afonso
authors.forename: Claude
authors.initials: C
authors.lastname: Wolf
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Tabet
authors.forename: Christophe
authors.initials: C
authors.lastname: Lamaze
authors.forename: Ludger
authors.initials: L
authors.lastname: Johannes
mesh_terms: D001693:Biological Transport, Active; D002462:Cell Membrane / Q000378:metabolism; D011992:Endosomes / Q000502:physiology; D006367:HeLa Cells; D006801:Humans; D021962:Membrane Microdomains / Q000378:metabolism; D008954:Models, Biological; D020033:Protein Isoforms / Q000032:analysis; D011956:Receptors, Cell Surface / Q000378:metabolism / Q000502:physiology; D022621:Shiga Toxin / Q000378:metabolism; D014281:Trihexosylceramides / Q000032:analysis / Q000378:metabolism / Q000502:physiology*; D021601:trans-Golgi Network / Q000502:physiology
chemical_list: D020033:Protein Isoforms; D011956:Receptors, Cell Surface; D014281:Trihexosylceramides; C018549:globotriaosylceramide; D022621:Shiga Toxin