title: Helicobacter pylori VacA cytotoxin: a probe for a clathrin-independent and Cdc42-dependent pinocytic pathway routed to late endosomes.
abstract: The vacuolating cytotoxin VacA is a major virulence factor of Helicobacter pylori, a bacterium responsible for gastroduodenal ulcers and cancer. VacA associates with lipid rafts, is endocytosed, and reaches the late endocytic compartment where it induces vacuolation. We have investigated the endocytic and intracellular trafficking pathways used by VacA, in HeLa and gastric AGS cells. We report here that VacA was first bound to plasma-membrane domains localized above F-actin structures that were controlled by the Rac1 GTPase. VacA was subsequently pinocytosed by a clathrin-independent mechanism into cell peripheral early endocytic compartments lacking caveolin 1, the Rab5 effector early endosomes antigen-1 (EEA1) and transferrin. These compartments took up fluid-phase (as evidenced by the accumulation of fluorescent dextran) and glycosylphosphatidylinositol-anchored proteins (GPI-APs). VacA pinocytosis was controlled by Cdc42 and did not require cellular tyrosine kinases, dynamin 2, ADP-ribosylating factor 6, or RhoA GTPase activities. VacA was subsequently routed to EEA1-sorting endosomes and then sorted to late endosomes. During all these different endocytic steps, VacA was continuously associated with detergent resistant membrane domains. From these results we propose that VacA might be a valuable probe to study raft-associated molecules, pinocytosed by a clathrin-independent mechanism, and routed to the degradative compartment.
authors.affiliation: INSERM U 627, IFR 50, Faculté de Médecine, 06107 Nice, France.
authors.forename: Nils C
authors.initials: NC
authors.lastname: Gauthier
authors.forename: Pascale
authors.initials: P
authors.lastname: Monzo
authors.forename: Vincent
authors.initials: V
authors.lastname: Kaddai
authors.forename: Anne
authors.initials: A
authors.lastname: Doye
authors.forename: Vittorio
authors.initials: V
authors.lastname: Ricci
authors.forename: Patrice
authors.initials: P
authors.lastname: Boquet
mesh_terms: D000089982:ADP-Ribosylation Factor 6; D020727:ADP-Ribosylation Factors / Q000378:metabolism; D000199:Actins / Q000378:metabolism; D001426:Bacterial Proteins / Q000502:physiology*; D001427:Bacterial Toxins / Q000378:metabolism*; D051242:Caveolin 1 / Q000378:metabolism; D015815:Cell Adhesion Molecules / Q000378:metabolism; D002460:Cell Line; D002966:Clathrin / Q000502:physiology*; D034285:Dynamin II / Q000378:metabolism; D011992:Endosomes / Q000502:physiology*; D016480:Helicobacter pylori / Q000502:physiology*; D006801:Humans; D021962:Membrane Microdomains / Q000502:physiology; D008565:Membrane Proteins / Q000378:metabolism; D010873:Pinocytosis / Q000502:physiology*; D014168:Transferrin / Q000378:metabolism; D033921:Vesicular Transport Proteins; D037521:Virulence Factors / Q000502:physiology*; D020764:cdc42 GTP-Binding Protein / Q000502:physiology*; D020696:rab5 GTP-Binding Proteins / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000378:metabolism
chemical_list: D000089982:ADP-Ribosylation Factor 6; D000199:Actins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D051242:Caveolin 1; D015815:Cell Adhesion Molecules; D002966:Clathrin; D008565:Membrane Proteins; D014168:Transferrin; C074689:VacA protein, Helicobacter pylori; D033921:Vesicular Transport Proteins; D037521:Virulence Factors; C093846:early endosome antigen 1; D020727:ADP-Ribosylation Factors; D020764:cdc42 GTP-Binding Protein; D020696:rab5 GTP-Binding Proteins; D020830:rac1 GTP-Binding Protein; D020742:rhoA GTP-Binding Protein; D034285:Dynamin II