RRC ID 28583
Author Yang JH, Shin BY, Han JY, Kim MG, Wi JE, Kim YW, Cho IJ, Kim SC, Shin SM, Ki SH.
Title Isorhamnetin protects against oxidative stress by activating Nrf2 and inducing the expression of its target genes.
Journal Toxicol Appl Pharmacol
Abstract Isorhamentin is a 3'-O-methylated metabolite of quercetin, and has been reported to have anti-inflammatory and anti-proliferative effects. However, the effects of isorhamnetin on Nrf2 activation and on the expressions of its downstream genes in hepatocytes have not been elucidated. Here, we investigated whether isorhamnetin has the ability to activate Nrf2 and induce phase II antioxidant enzyme expression, and to determine the protective role of isorhamnetin on oxidative injury in hepatocytes. In HepG2 cells, isorhamnetin increased the nuclear translocation of Nrf2 in a dose- and time-dependent manner, and consistently, increased antioxidant response element (ARE) reporter gene activity and the protein levels of hemeoxygenase (HO-1) and of glutamate cysteine ligase (GCL), which resulted in intracellular GSH level increases. The specific role of Nrf2 in isorhamnetin-induced Nrf2 target gene expression was verified using an ARE-deletion mutant plasmid and Nrf2-knockout MEF cells. Deletion of the ARE in the promoter region of the sestrin2 gene, which is recently identified as the Nrf2 target gene by us, abolished the ability of isorhamnetin to increase luciferase activity. In addition, Nrf2 deficiency completely blocked the ability of isorhamnetin to induce HO-1 and GCL. Furthermore, isorhamnetin pretreatment blocked t-BHP-induced ROS production and reversed GSH depletion by t-BHP and consequently, due to reduced ROS levels, decreased t-BHP-induced cell death. In addition isorhamnetin increased ERK1/2, PKCδ and AMPK phosphorylation. Finally, we showed that Nrf2 deficiency blocked the ability of isorhamnetin to protect cells from injury induced by t-BHP. Taken together, our results demonstrate that isorhamnetin is efficacious in protecting hepatocytes against oxidative stress by Nrf2 activation and in inducing the expressions of its downstream genes.
Volume 274(2)
Pages 293-301
Published 2014-1-15
DOI 10.1016/j.taap.2013.10.026
PII S0041-008X(13)00474-2
PMID 24211276
MeSH AMP-Activated Protein Kinases / genetics AMP-Activated Protein Kinases / metabolism Anti-Inflammatory Agents / pharmacology* Antioxidant Response Elements / drug effects Antioxidants / pharmacology Cell Proliferation / drug effects Cell Survival / drug effects Glutamate-Cysteine Ligase / genetics Glutamate-Cysteine Ligase / metabolism Glutathione / metabolism Heme Oxygenase-1 / genetics Heme Oxygenase-1 / metabolism Hep G2 Cells Hepatocytes / drug effects Hepatocytes / metabolism Humans MAP Kinase Signaling System / drug effects NF-E2-Related Factor 2 / genetics NF-E2-Related Factor 2 / metabolism* Oxidative Stress / drug effects* Phosphorylation Protein Kinase C-delta / genetics Protein Kinase C-delta / metabolism Quercetin / analogs & derivatives* Quercetin / pharmacology tert-Butylhydroperoxide / toxicity
IF 3.347
Times Cited 59
DNA material pGL4-phSESN2 (RDB07413)