TY - JOUR
T1 - Carbon monoxide activates NF-κB via ROS generation and Akt pathways to protect against cell death of hepatocytes
AU - Kim, Hoe Suk
AU - Loughran, Patricia A.
AU - Rao, Jayashree
AU - Billiar, Timothy R.
AU - Zuckerbraun, Brian S.
PY - 2008/7
Y1 - 2008/7
N2 - Heme oxygenase overexpression or exogenous carbon monoxide (CO) protects against hepatocyte apoptosis and fulminant hepatitis. The prevention of hepatocyte apoptosis by CO has been shown to require activation of NF-κB. The purpose of these investigations was to determine the mechanism of CO-induced hepatocyte NF-κB activation and protection against apoptosis. Primary rat or mouse hepatocytes and Hep3B cells were utilized. CO exposure was performed at 250 parts per million. Main outcome measures included cell viability, reactive oxygen species (ROS) generation, and changes in the levels of the intracellular antioxidants glutathione and ascorbate. Western blotting was performed for phospho-Akt, total Akt, and IκBα. NF-κB activation was determined by electrophoretic mobility shift assay and luciferase reporter assays. We found that CO treatment of hepatocytes prevents spontaneous apoptosis and leads to an increase in ROS production in association with Akt phosphorylation and IκB degradation. CO did not increase ROS production in respiration-deficient (ρ0) Hep3B cells. Both Akt phosphorylation and IκB degradation can be inhibited by the addition of antioxidants. Furthermore, CO-induced NF-κB activation is reversed by phosphatidylinositol 3-kinase (PI3-K) inhibitor (LY294002) or antioxidants. Additionally, prevention of spontaneous hepatocyte apoptosis by CO is reversed by PI3-K inhibition and antioxidants. In conclusion, these data implicate a survival pathway of CO-induced ROS, Akt phosphorylation, and NF-κB activation in cultured hepatocytes. This pathway may prove to be important in maintenance of hepatic function in both physiological and pathophysiological conditions.
AB - Heme oxygenase overexpression or exogenous carbon monoxide (CO) protects against hepatocyte apoptosis and fulminant hepatitis. The prevention of hepatocyte apoptosis by CO has been shown to require activation of NF-κB. The purpose of these investigations was to determine the mechanism of CO-induced hepatocyte NF-κB activation and protection against apoptosis. Primary rat or mouse hepatocytes and Hep3B cells were utilized. CO exposure was performed at 250 parts per million. Main outcome measures included cell viability, reactive oxygen species (ROS) generation, and changes in the levels of the intracellular antioxidants glutathione and ascorbate. Western blotting was performed for phospho-Akt, total Akt, and IκBα. NF-κB activation was determined by electrophoretic mobility shift assay and luciferase reporter assays. We found that CO treatment of hepatocytes prevents spontaneous apoptosis and leads to an increase in ROS production in association with Akt phosphorylation and IκB degradation. CO did not increase ROS production in respiration-deficient (ρ0) Hep3B cells. Both Akt phosphorylation and IκB degradation can be inhibited by the addition of antioxidants. Furthermore, CO-induced NF-κB activation is reversed by phosphatidylinositol 3-kinase (PI3-K) inhibitor (LY294002) or antioxidants. Additionally, prevention of spontaneous hepatocyte apoptosis by CO is reversed by PI3-K inhibition and antioxidants. In conclusion, these data implicate a survival pathway of CO-induced ROS, Akt phosphorylation, and NF-κB activation in cultured hepatocytes. This pathway may prove to be important in maintenance of hepatic function in both physiological and pathophysiological conditions.
KW - Antioxidant
KW - Heme oxygenase
KW - IκBα
KW - Mitochondria
KW - PI3-kinase
UR - http://www.scopus.com/inward/record.url?scp=51149088154&partnerID=8YFLogxK
U2 - 10.1152/ajpgi.00105.2007
DO - 10.1152/ajpgi.00105.2007
M3 - Article
C2 - 18497334
AN - SCOPUS:51149088154
SN - 0193-1857
VL - 295
SP - G146-G152
JO - American Journal of Physiology - Gastrointestinal and Liver Physiology
JF - American Journal of Physiology - Gastrointestinal and Liver Physiology
IS - 1
ER -