title: Role of pannexin 1 in Clostridium perfringens beta-toxin-caused cell death.
abstract: Beta-toxin produced by Clostridium perfringens is a key virulence factor of fatal hemorrhagic enterocolitis and enterotoxemia. This toxin belongs to a family of β-pore-forming toxins (PFTs). We reported recently that the ATP-gated P2X7receptor interacts with beta-toxin. The ATP-release channel pannexin 1 (Panx1) is an important contributor to P2X7receptor signaling. Hence, we investigated the involvement of Panx1 in beta-toxin-caused cell death.
  
  
  
  We examined the effect of Panx1 in beta-toxin-induced cell death utilizing selective antagonists, knockdown of Panx1, and binding using dot-blot analysis. Localization of Panx1 and the P2X7receptor after toxin treatment was determined by immunofluorescence staining.
  
  
  
  Selective Panx1 antagonists (carbenoxolone [CBX], probenecid, and Panx1 inhibitory peptide) prevented beta-toxin-caused cell death in THP-1 cells. CBX did not block the binding of the toxin to cells. Small interfering knockdown of Panx1 blocked beta-toxin-mediated cell death through inhibiting the oligomer formation of the toxin. Beta-toxin triggered a transient ATP release from THP-1 cells, but this early ATP release was blocked by CBX. ATP scavengers (apyrase and hexokinase) inhibited beta-toxin-induced cytotoxicity. Furthermore, co-administration of ATP with beta-toxin enhanced the binding and cytotoxicity of the toxin.
  
  
  
  Based on our results, Panx1 activation is achieved through the interaction of beta-toxin with the P2X7receptor. Then, ATP released by the Panx1 channel opening promotes oligomer formation of the toxin, leading to cell death.
  
  
  
  Pannexin 1 is a novel candidate therapeutic target for beta-toxin-mediated disease.
authors.affiliation: Department of Microbiology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho 180, Tokushima 770-8514, Japan.
authors.forename: Soshi
authors.initials: S
authors.lastname: Seike
authors.affiliation: Department of Microbiology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho 180, Tokushima 770-8514, Japan.
authors.forename: Masaya
authors.initials: M
authors.lastname: Takehara
authors.affiliation: Department of Microbiology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho 180, Tokushima 770-8514, Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Kobayashi
authors.affiliation: Department of Microbiology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho 180, Tokushima 770-8514, Japan. Electronic address: nagahama@ph.bunri-u.ac.jp.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Nagahama
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D001081:Apyrase / Q000494:pharmacology; D001427:Bacterial Toxins / Q000633:toxicity*; D002229:Carbenoxolone / Q000494:pharmacology; D016923:Cell Death / Q000187:drug effects; D002478:Cells, Cultured; D017630:Connexins / Q000502:physiology*; D006593:Hexokinase / Q000494:pharmacology; D006801:Humans; D009419:Nerve Tissue Proteins / Q000502:physiology*; D058486:Receptors, Purinergic P2X7 / Q000502:physiology
chemical_list: D001427:Bacterial Toxins; C031884:CPB protein, Clostridium perfringens; D017630:Connexins; D009419:Nerve Tissue Proteins; C546468:P2RX7 protein, human; C492764:PANX1 protein, human; D058486:Receptors, Purinergic P2X7; D000255:Adenosine Triphosphate; D006593:Hexokinase; D001081:Apyrase; D002229:Carbenoxolone
keywords: C. perfringens beta-toxin; Oligomer formation; Pannexin 1; Pore-forming toxin