title: Signal transduction mechanism involved in Clostridium perfringens alpha-toxin-induced superoxide anion generation in rabbit neutrophils.
abstract: Clostridium perfringens alpha-toxin induces the generation of superoxide anion (O2(-)) via production of 1,2-diacylglycerol (DG) in rabbit neutrophils. The mechanism of the generation, however, remains poorly understood. Here we report a novel mechanism for the toxin-induced production of O2(-) in rabbit neutrophils. Treatment of the cells with the toxin resulted in tyrosine phosphorylation of a protein of about 140 kDa. The protein reacted with anti-TrkA (nerve growth factor high-affinity receptor) antibody and bound nerve growth factor. Anti-TrkA antibody inhibited the production of O2(-) and binding of the toxin to the protein. The toxin induced phosphorylation of 3-phosphoinositide-dependent protein kinase 1 (PDK1). K252a, an inhibitor of TrkA receptor, and LY294002, an inhibitor of phosphatidylinositol 3-kinase (PI3K), reduced the toxin-induced production of O2(-) and phosphorylation of PDK1, but not the formation of DG. These inhibitors inhibited the toxin-induced phosphorylation of protein kinase C theta (PKCtheta). U73122, a phospholipase C (PLC) inhibitor, and pertussis toxin inhibited the toxin-induced generation of O2(-) and formation of DG, but not the phosphorylation of PDK1. These observations show that the toxin independently induces production of DG through activation of endogenous PLC and phosphorylation of PDK1 via the TrkA receptor signaling pathway and that these events synergistically activate PKCtheta in stimulating an increase in O2(-). In addition, we show the participation of mitogen-activated protein kinase-associated signaling events via activation of PKCtheta in the toxin-induced generation of O2(-).
authors.affiliation: Faculty of Pharmaceutical Sciences, Department of Microbiology, Tokushima Bunri University, Yamashiro-cho, Tokushima 770-8514, Japan.
authors.forename: Masataka
authors.initials: M
authors.lastname: Oda
authors.forename: Syusuke
authors.initials: S
authors.lastname: Ikari
authors.forename: Takayuki
authors.initials: T
authors.lastname: Matsuno
authors.forename: Yuka
authors.initials: Y
authors.lastname: Morimune
authors.forename: Masahiro
authors.initials: M
authors.lastname: Nagahama
authors.forename: Jun
authors.initials: J
authors.lastname: Sakurai
mesh_terms: D064413:3-Phosphoinositide-Dependent Protein Kinases; D000818:Animals; D001427:Bacterial Toxins / Q000633:toxicity*; D002135:Calcium-Binding Proteins / Q000633:toxicity*; D004075:Diglycerides / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000502:physiology; D020935:MAP Kinase Signaling System / Q000502:physiology; D009504:Neutrophils / Q000187:drug effects* / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology; D011493:Protein Kinase C / Q000502:physiology; D017346:Protein Serine-Threonine Kinases / Q000502:physiology; D011817:Rabbits; D020917:Receptor, trkA / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D013481:Superoxides / Q000378:metabolism*; D010738:Type C Phospholipases / Q000633:toxicity*; D048051:p38 Mitogen-Activated Protein Kinases / Q000502:physiology
chemical_list: D064413:3-Phosphoinositide-Dependent Protein Kinases; D001427:Bacterial Toxins; D002135:Calcium-Binding Proteins; D004075:Diglycerides; D048049:Extracellular Signal-Regulated MAP Kinases; D019869:Phosphatidylinositol 3-Kinases; D011493:Protein Kinase C; D017346:Protein Serine-Threonine Kinases; D020917:Receptor, trkA; D013481:Superoxides; D010738:Type C Phospholipases; D048051:p38 Mitogen-Activated Protein Kinases; C038237:1-oleoyl-2-acetylglycerol; C040649:alpha toxin, Clostridium perfringens