title: Shiga toxin binding to globotriaosyl ceramide induces intracellular signals that mediate cytoskeleton remodeling in human renal carcinoma-derived cells.
abstract: Shiga toxin is a bacterial toxin consisting of A and B subunits. Generally, the essential cytotoxicity of the toxin is thought to be mediated by the A subunit, which possesses RNA cleavage activity and thus induces protein synthesis inhibition. We previously reported, however, that the binding of the Shiga toxin 1-B subunit to globotriaosyl ceramide, a functional receptor for Shiga toxin, induces intracellular signals in a manner that is dependent on glycolipid-enriched membrane domains, or lipid rafts. Although the precise role of this signaling mechanism is not known, here we report that Shiga-toxin-mediated intracellular signals induce cytoskeleton remodeling in ACHN cells derived from renal tubular epithelial carcinoma. Using confocal laser scanning microscopy, we observed that Shiga toxin 1-B treatment induces morphological changes in ACHN cells in a time-dependent manner. In addition, the morphological changes were accompanied by the redistribution of a number of proteins, including actin, ezrin, CD44, vimentin, cytokeratin, paxillin, FAK, and alpha- and gamma-tubulins, all of which are involved in cytoskeletal organization. The transient phosphorylation of ezrin and paxillin was also observed during the course of protein redistribution. Experiments using inhibitors for a variety of kinases suggested the involvement of lipid rafts, Src family protein kinase, PI 3-kinase, and RHO-associated kinase in Shiga toxin 1-B-induced ezrin phosphorylation. Shiga toxin 1-B-induced cytoskeletal remodeling should provide an in vitro model that can be used to increase our understanding of the pathogenesis of Shiga-toxin-mediated cell injury and the role of lipid-raft-mediated cell signaling in cytoskeletal remodeling.
authors.affiliation: Department of Developmental Biology, National Research Institute for Child Health and Development, 3-35-31, Taishido, Setagaya-ku, Tokyo, 154-8567, Japan.
authors.forename: Hisami
authors.initials: H
authors.lastname: Takenouchi
authors.forename: Nobutaka
authors.initials: N
authors.lastname: Kiyokawa
authors.forename: Tomoko
authors.initials: T
authors.lastname: Taguchi
authors.forename: Jun
authors.initials: J
authors.lastname: Matsui
authors.forename: Yohko U
authors.initials: YU
authors.lastname: Katagiri
authors.forename: Hajime
authors.initials: H
authors.lastname: Okita
authors.forename: Kenji
authors.initials: K
authors.lastname: Okuda
authors.forename: Junichiro
authors.initials: J
authors.lastname: Fujimoto
mesh_terms: D000199:Actins / Q000378:metabolism; D002277:Carcinoma / Q000473:pathology*; D002460:Cell Line; D045744:Cell Line, Tumor; D003598:Cytoskeletal Proteins / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism*; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D006801:Humans; D018960:Hyaluronan Receptors / Q000096:biosynthesis; D015151:Immunoblotting; D007150:Immunohistochemistry; D007668:Kidney / Q000378:metabolism; D007680:Kidney Neoplasms / Q000378:metabolism / Q000473:pathology*; D050356:Lipid Metabolism; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D051419:Paxillin; D010750:Phosphoproteins / Q000737:chemistry / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D012313:RNA / Q000378:metabolism; D022621:Shiga Toxin / Q000378:metabolism*; D022622:Shiga Toxin 1 / Q000378:metabolism; D015398:Signal Transduction; D013997:Time Factors; D014281:Trihexosylceramides / Q000737:chemistry* / Q000378:metabolism; D014404:Tubulin / Q000378:metabolism; D014746:Vimentin / Q000737:chemistry / Q000378:metabolism; D000099149:Ezrin
chemical_list: D000199:Actins; D003598:Cytoskeletal Proteins; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D018960:Hyaluronan Receptors; D051419:Paxillin; D010750:Phosphoproteins; D011505:Protein-Tyrosine Kinases; D012313:RNA; D022621:Shiga Toxin; D022622:Shiga Toxin 1; D014281:Trihexosylceramides; D014404:Tubulin; D014746:Vimentin; D000099149:Ezrin; C496061:PXN protein, human; C018549:globotriaosylceramide; C496050:PTK2 protein, human