Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10738550 | Free Radical Biology and Medicine | 2011 | 12 Pages |
Abstract
Thioredoxin is an important reducing molecule in biological systems. Increasing CYP2E1 activity induces oxidative stress and cell toxicity. However, whether thioredoxin protects cells against CYP2E1-induced oxidative stress and toxicity is unknown. SiRNA were used to knockdown either cytosolic (TRX-1) or mitochondrial thioredoxin (TRX-2) in HepG2 cells expressing CYP2E1 (E47 cells) or without expressing CYP2E1 (C34 cells). Cell viability decreased 40-60% in E47 but not C34 cells with 80-90% knockdown of either TRX-1 or TRX-2. Depletion of either thioredoxin also potentiated the toxicity produced either by a glutathione synthesis inhibitor or by TNFα in E47 cells. Generation of reactive oxygen species and 4-HNE protein adducts increased in E47 but not C34 cells with either thioredoxin knockdown. GSH was decreased and adding GSH completely blocked E47 cell death induced by either thioredoxin knockdown. Lowering TRX-1 or TRX-2 in E47 cells caused an early activation of ASK-1, followed by phosphorylation of JNK1 after 48 h of siRNA treatment. A JNK inhibitor caused a partial recovery of E47 cell viability after thioredoxin knockdown. In conclusion, knockdown of TRX-1 or TRX-2 sensitizes cells to CYP2E1-induced oxidant stress partially via ASK-1 and JNK1 signaling pathways. Both TRX-1 and TRX-2 are important for defense against CYP2E1-induced oxidative stress.
Keywords
ASK-1TNFαTrx-1Jnk4-HNE4-hydroxynonenalCYP2E1c-Jun NH2-terminal kinaseBSOPDI3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromideMAPKMTTROSOxidative stresstumor necrosis factor αthioredoxinDihydroethidineHepG2 cellsCell toxicitycytochrome P4502E1endoplasmic reticulumDHEmitogen-activated protein kinaseApoptosis signal-regulating kinase-1Glutathione ethyl esterReactive oxygen species
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Authors
Lili Yang, Defeng Wu, Xiaodong Wang, Arthur I. Cederbaum,