title: Mechanism of Clostridium difficile toxin A-induced apoptosis in T84 cells.
abstract: This study is an investigation into the mechanism of Clostridium difficile toxin A-induced apoptosis in human intestinal epithelial cells. Toxin A induced apoptosis of T84 cells in a dose- and time-dependent fashion. Toxin A-induced apoptosis was completely inhibited by blocking toxin enzymatic activity on Rho GTPases with uridine 5'-diphosphate-2',3'-dialdehyde by a nonspecific caspase inhibitor and was partially inhibited by caspase-1, -3, -6, -8, and -9 inhibitors. Caspases 3, 6, 8, and 9 and Bid activation were detected. Toxin A also induced changes in mitochondrial membrane potential and cytochrome c release at 18-24 h, a time course similar to caspase-9 activation. In conclusion, toxin A induces apoptosis by a mechanism dependent on inactivation of Rho, activation of caspases 3, 6, 8, and 9 and Bid, and mitochondrial damage followed by cytochrome c release. Toxin A proapoptotic activity may contribute to the mucosal disruption seen in toxin A-induced enteritis.
authors.affiliation: Department of Morphology, Federal University of Ceará, Fortaleza, Brazil.
authors.forename: Gerly A C
authors.initials: GA
authors.lastname: Brito
authors.forename: Jun
authors.initials: J
authors.lastname: Fujji
authors.forename: Benedito A
authors.initials: BA
authors.lastname: Carneiro-Filho
authors.forename: Aldo A M
authors.initials: AA
authors.lastname: Lima
authors.forename: Tom
authors.initials: T
authors.lastname: Obrig
authors.forename: Richard L
authors.initials: RL
authors.lastname: Guerrant
mesh_terms: D017304:Annexin A5 / Q000494:pharmacology; D000906:Antibodies / Q000494:pharmacology; D017209:Apoptosis; D051023:BH3 Interacting Domain Death Agonist Protein; D001427:Bacterial Toxins / Q000494:pharmacology*; D002352:Carrier Proteins / Q000378:metabolism; D053181:Caspase 8; D053453:Caspase 9; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D002478:Cells, Cultured; D003574:Cytochrome c Group / Q000378:metabolism; D053938:DNA Fragmentation / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004768:Enterotoxins / Q000494:pharmacology*; D006801:Humans; D008564:Membrane Potentials / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects* / Q000502:physiology; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D017304:Annexin A5; D000906:Antibodies; D051023:BH3 Interacting Domain Death Agonist Protein; C494814:BID protein, human; D001427:Bacterial Toxins; D002352:Carrier Proteins; D061945:Caspase Inhibitors; D003574:Cytochrome c Group; D004768:Enterotoxins; D014409:Tumor Necrosis Factor-alpha; C041348:tcdA protein, Clostridium difficile; C505530:CASP8 protein, human; C506433:CASP9 protein, human; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases; D020741:rho GTP-Binding Proteins