title: Rho GTPase is activated by cytotoxic necrotizing factor 1 in peripheral blood T lymphocytes: potential cytotoxicity for intestinal epithelial cells.
abstract: Some strains of Escherichia coli related to acute cystitis or colitis produce a toxin named cytotoxic necrotizing factor 1 (CNF-1). CNF-1 mediates its effects on epithelial cells or phagocytes via the permanent activation of small GTP-binding proteins, caused by the toxin-induced deamidation of Glu(63) of p21 Rho. The behavior of peripheral blood T lymphocytes during the acute phase of bacterial colitis has been poorly investigated. Our study was conducted to test whether (i) peripheral blood T lymphocytes can be activated by CNF-1 and (ii) CNF-1-activated T lymphocytes are cytotoxic against intestinal epithelial cells. Activation of T lymphocytes by CNF-1 was assessed by electrophoresis, flow cytometry, confocal microscopy, and electron microscopy studies. Assays for migration and adherence of CNF-1-treated T lymphocytes were performed in Transwell chambers with T84 intestinal epithelial cells grown on polycarbonate semipermeable filters. CNF-1 induced a decrease in the electrophoretic mobility of the GTP-binding protein Rho in treated T lymphocytes. CNF-1 provoked an increase in the content of actin stress fibers and pseudopodia in T lymphocytes. Several adherence molecules were clustered into cytoplasmic projections in CNF-1-treated T lymphocytes and adherence of such lymphocytes on the basolateral pole of T84 was increased, resulting in cytotoxicity toward epithelial cells. Such enhanced adherence in response to CNF-1 was dependent on p42-44(MAP) kinase activation of T lymphocytes. Taken together, these results suggest that CNF-1, by acting on T lymphocytes, may increase in an important fashion the virulence of certain strains of E. coli against the intestinal epithelia.
authors.affiliation: INSERM 364, Faculté de Médecine, 06107 Nice Cédex 02, France.
authors.forename: Patrick
authors.initials: P
authors.lastname: Brest
authors.forename: Baharia
authors.initials: B
authors.lastname: Mograbi
authors.forename: Véronique
authors.initials: V
authors.lastname: Hofman
authors.forename: Agnès
authors.initials: A
authors.lastname: Loubat
authors.forename: Bernard
authors.initials: B
authors.lastname: Rossi
authors.forename: Patrick
authors.initials: P
authors.lastname: Auberger
authors.forename: Paul
authors.initials: P
authors.lastname: Hofman
mesh_terms: D001427:Bacterial Toxins / Q000633:toxicity*; D040881:CD11a Antigen / Q000378:metabolism; D002448:Cell Adhesion / Q000187:drug effects; D002465:Cell Movement / Q000187:drug effects; D054377:Chemokine CXCL12; D019743:Chemokines, CXC / Q000494:pharmacology; D003603:Cytotoxins / Q000633:toxicity*; D004789:Enzyme Activation; D029968:Escherichia coli Proteins; D006801:Humans; D016130:Immunophenotyping; D019012:Integrin beta1 / Q000378:metabolism; D007413:Intestinal Mucosa / Q000187:drug effects*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D013601:T-Lymphocytes / Q000187:drug effects* / Q000201:enzymology / Q000502:physiology; D016212:Transforming Growth Factor beta / Q000096:biosynthesis; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis; D020741:rho GTP-Binding Proteins / Q000378:metabolism*
chemical_list: D001427:Bacterial Toxins; D040881:CD11a Antigen; C515255:CXCL12 protein, human; D054377:Chemokine CXCL12; D019743:Chemokines, CXC; D003603:Cytotoxins; D029968:Escherichia coli Proteins; D019012:Integrin beta1; D016212:Transforming Growth Factor beta; D014409:Tumor Necrosis Factor-alpha; C060296:cytotoxic necrotizing factor type 1; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D020741:rho GTP-Binding Proteins