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Author Song, Jae-Sook ♦ Kim, Eun-Kyung ♦ Choi, Yong-Won
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword APPLIED LIFE SCIENCES ♦ ADP ♦ AMP ♦ ANTIOXIDANTS ♦ APOPTOSIS ♦ BENZOQUINONES ♦ BIOSYNTHESIS ♦ CALMODULIN ♦ CYSTEINE ♦ ECR HEATING ♦ GLUTATHIONE ♦ GLYCOGEN ♦ HEMAGGLUTININS ♦ HEME ♦ INACTIVATION ♦ INHIBITION ♦ INJURIES ♦ LIGASES ♦ LIVER ♦ LIVER CELLS ♦ LUCIFERASE ♦ MICE ♦ MITOGENS ♦ NAD ♦ OXIDATION ♦ OXYGENASES ♦ PHOSPHORYLATION ♦ POLYMERASE CHAIN REACTION ♦ RIBOSE ♦ SAFETY
Abstract Oxidative stress can contribute to the development and progression of liver diseases, such as drug-induced or alcoholic liver injury, nonalcoholic fatty liver disease, and nonalcoholic steatohepatitis. Nectandrin B is a bioactive lignan isolated from nutmeg extract. To date, little information is available about its pharmacological activities in the liver. This study investigated the hepatocyte-protective effect of nectandrin B against tert-butylhydroperoxide-induced oxidative injury and the underlying molecular mechanism. The cell viability assay revealed that nectandrin B prevents apoptosis stimulated by tert-butylhydroperoxide in both HepG2 cells and primary mouse hepatocytes. Nectandrin B also attenuated ROS production and restored the depleted glutathione level. Real-time PCR and immunoblot analyses showed that the expression of glutamate-cysteine ligase, an enzyme responsible for the glutathione biosynthesis, was induced by nectandrin B, indicating its indirect antioxidative effect. The NF-E2-related factor-2 (Nrf2) regulates gene expression of an array of antioxidant enzymes in hepatocytes. Nectandrin B stimulated Nrf2 activation as evidenced by its enhanced nuclear accumulation and increased antioxidant response element (ARE)-luciferase activity. Intriguingly, the hepatocyte-protective effect of nectandrin B against oxidative damage was completely abrogated by Nrf2 knockdown using Nrf2 specific siRNA. Nectandrin B promoted ERK activation, but inactivated GSK-3β through the AMPK-mediated inhibitory phosphorylation. The enforced overexpression of dominant-negative mutant of MEK1 or AMPKα, or wild-type GSK-3β inhibited the increase in the NQO1-ARE-luciferase activity stimulated by nectandrin B, suggesting that both ERK and AMPK-GSK-3β signalings are involved in the activation of Nrf2/ARE pathway by nectandrin B. Consistent with this, cytoprotection and restoration of glutathione level by nectandrin B was also blocked by the overexpression of dominant-negative MEK1 or wild-type GSK-3β. Finally, our data demonstrate that nectandrin B has the ability to protect hepatocytes against oxidative injury through the activation of Nrf2/ARE pathway mediated by ERK phosphorylation and AMPK-dependent inactivation of GSK-3β. - Highlight: • Nectandrin B, a nutmeg lignan protects hepatocytes against oxidative damage. • Nectandrin B exerts an indirect antioxidative effect via the activation of Nrf2. • Both ERK and GSK-3β pathways contribute to the activation of Nrf2 and hepatocyte-protection by nectandrin B. • Nectandrin B can inactivate GSK-3β through the activation of AMPK in HepG2 cells.
ISSN 0041008X
Educational Use Research
Learning Resource Type Article
Publisher Date 2016-09-15
Publisher Place United States
Journal Toxicology and Applied Pharmacology
Volume Number 307


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