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.

CONCLUSION:

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: Nobuko Harada, Yuji Iimuro, Takashi Nitta, Masanori Yoshida, Hiroshi Uchinami, Toshihiro Nishio, Etsuro Hatano, Naritaka Yamamoto, Yuzo Yamamoto, Yoshio Yamaoka
• Journal: Surgery (Surgery) Vol. 134 Issue 3 Pg. 480-91 (Sep 2003) ISSN: 0039-6060 [Print] United States
• PMID: 14555937 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• NF-kappa B
• Reactive Oxygen Species
• DNA
• rac1 GTP-Binding Protein

Topics

• Active Transport, Cell Nucleus
• Adenoviridae (genetics)
• Animals
• DNA (metabolism)
• Gene Transfer, Horizontal
• Liver (blood supply)
• Male
• Mutation
• NF-kappa B (metabolism)
• Rats
• Rats, Sprague-Dawley
• Reactive Oxygen Species
• Reperfusion Injury (prevention & control)
• rac1 GTP-Binding Protein (genetics, physiology)