title: Inactivation of the small GTPase Rac1 protects the liver from ischemia/reperfusion injury in the rat.
abstract: BACKGROUND
  In ischemia/reperfusion (I/R) injury, a massive generation of reactive oxygen species (ROS) after reperfusion is a critical factor. Rac, a member of the Rho GTPase superfamily, plays important roles in the production of ROS and activation of nuclear factor-kappaB (NF-kappaB) in vitro. However, the exact role of Rac in the ROS production and NF-kappaB activation in vivo after I/R is still obscure.
  
  
  METHODS
  We blocked Rac1 activity in the rat liver using adenovirus encoding a dominant negative rac1 mutant (Ad5N17Rac1) and examined whether inactivation of Rac1 could prevent ROS generation in the hepatic I/R injury. Seventy-two hours after the adenoviral infection, hepatic I/R was induced by Pringle's maneuver for 20 minutes, followed by reperfusion in the rats.
  
  
  RESULTS
  Ad5N17Rac1 infection significantly attenuated ROS production after reperfusion and suppressed the hepatic injury. Furthermore, N17Rac1 suppressed NF-kappaB activation and messenger RNA expression of tumor necrosis factor-alpha (TNF-alpha) and inducible nitric oxide synthetase (iNOS). Ad5LacZ, a control adenovirus, had no effect on the induced hepatic I/R injury, nor did it affect NF-kappaB activation. Immunohistochemical analysis of NF-kappaB (p65) revealed that translocation of p65 to the nucleus after reperfusion was blocked in many of non-parenchymal cells (NPCs) and in hepatocytes in the Ad5N17Rac1-infected liver.
  
  
  CONCLUSIONS
  We conclude that Rac1 is required in ROS generation and NF-kappaB activation after hepatic I/R in vivo, and that inactivation of NF-kappaB in NPCs and suppression of ROS generation in NPCs and hepatocytes possibly account for the protective effect of N17Rac1 in this study.
authors.affiliation: Department of Gastrointestinal Surgery, Kyoto University Graduate School of Medicine, Kyoto, Japan.
authors.forename: Nobuko
authors.initials: N
authors.lastname: Harada
authors.forename: Yuji
authors.initials: Y
authors.lastname: Iimuro
authors.forename: Takashi
authors.initials: T
authors.lastname: Nitta
authors.forename: Masanori
authors.initials: M
authors.lastname: Yoshida
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Uchinami
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Nishio
authors.forename: Etsuro
authors.initials: E
authors.lastname: Hatano
authors.forename: Naritaka
authors.initials: N
authors.lastname: Yamamoto
authors.forename: Yuzo
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Yamaoka
mesh_terms: D021581:Active Transport, Cell Nucleus; D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D004247:DNA / Q000378:metabolism; D022761:Gene Transfer, Horizontal; D008099:Liver / Q000098:blood supply*; D008297:Male; D009154:Mutation; D016328:NF-kappa B / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species; D015427:Reperfusion Injury / Q000517:prevention & control*; D020830:rac1 GTP-Binding Protein / Q000235:genetics / Q000502:physiology*
chemical_list: D016328:NF-kappa B; D017382:Reactive Oxygen Species; D004247:DNA; D020830:rac1 GTP-Binding Protein