title: Retrograde Shiga toxin trafficking is regulated by ARHGAP21 and Cdc42.
abstract: Shiga-toxin-producing Escherichia coli remain a food-borne health threat. Shiga toxin is endocytosed by intestinal epithelial cells and transported retrogradely through the secretory pathway. It is ultimately translocated to the cytosol where it inhibits protein translation. We found that Shiga toxin transport through the secretory pathway was dependent on the cytoskeleton. Recent studies reveal that Shiga toxin activates signaling pathways that affect microtubule reassembly and dynein-dependent motility. We propose that Shiga toxin alters cytoskeletal dynamics in a way that facilitates its transport through the secretory pathway. We have now found that Rho GTPases regulate the endocytosis and retrograde motility of Shiga toxin. The expression of RhoA mutants inhibited endocytosis of Shiga toxin. Constitutively active Cdc42 or knockdown of the Cdc42-specific GAP, ARHGAP21, inhibited the transport of Shiga toxin to the juxtanuclear Golgi apparatus. The ability of Shiga toxin to stimulate microtubule-based transferrin transport also required Cdc42 and ARHGAP21 function. Shiga toxin addition greatly decreases the levels of active Cdc42-GTP in an ARHGAP21-dependent manner. We conclude that ARHGAP21 and Cdc42-based signaling regulates the dynein-dependent retrograde transport of Shiga toxin to the Golgi apparatus.
authors.affiliation: Department of Molecular Physiology and Biophysics, Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, Iowa City, IA 52242, USA.
authors.forename: Heidi
authors.initials: H
authors.lastname: Hehnly
authors.forename: Katrina Marie
authors.initials: KM
authors.lastname: Longhini
authors.forename: Ji-Long
authors.initials: JL
authors.lastname: Chen
authors.forename: Mark
authors.initials: M
authors.lastname: Stamnes
mesh_terms: D000818:Animals; D002522:Chlorocebus aethiops; D003599:Cytoskeleton / Q000502:physiology*; D004705:Endocytosis / Q000502:physiology; D020690:GTPase-Activating Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D055785:Gene Knockdown Techniques; D006056:Golgi Apparatus / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000502:physiology; D018613:Microscopy, Confocal; D008870:Microtubules / Q000502:physiology; D021381:Protein Transport / Q000502:physiology; D034741:RNA, Small Interfering / Q000494:pharmacology; D011993:Recombinant Fusion Proteins / Q000502:physiology; D022603:Shiga Toxins / Q000378:metabolism* / Q000494:pharmacology; D014168:Transferrin / Q000502:physiology; D014709:Vero Cells / Q000378:metabolism; D020764:cdc42 GTP-Binding Protein / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D020830:rac1 GTP-Binding Protein / Q000235:genetics / Q000502:physiology; D020742:rhoA GTP-Binding Protein / Q000235:genetics / Q000502:physiology
chemical_list: D020690:GTPase-Activating Proteins; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins; D022603:Shiga Toxins; D014168:Transferrin; C077239:stxB toxin; D006160:Guanosine Triphosphate; D020764:cdc42 GTP-Binding Protein; D020830:rac1 GTP-Binding Protein; D020742:rhoA GTP-Binding Protein
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