title: Activation of ASK-1 and downstream MAP kinases in cytochrome P4502E1 potentiated tumor necrosis factor alpha liver injury.
abstract: Cytochrome P4502E1 (CYP2E1) potentiates TNFalpha toxicity by a mechanism involving increased oxidative stress and activation of JNK and p38 MAPKs. This study evaluated the upstream mediators of this MAPK activation with a special focus on studying whether apoptosis signal regulating kinase-1 (ASK-1) is activated in the CYP2E1-TNFalpha hepatotoxic model. Wild-type and CYP2E1(-/-) mice were treated with pyrazole (PY) for 3days to induce CYP2E1 and challenged with TNFalpha on day 3. Liver injury occurred between 8 and 12h after TNFalpha administration only to the wild-type PY-treated mice. Oxidative stress was elevated in the PY mice at 4h, a time before the liver injury. ASK-1 was dissociated from the thioredoxin-ASK-1 complex and was activated at 4h after administration of TNFalpha to PY mice. This was followed by activation of MKK3/MKK6 and MKK4/MKK7 at 4-8 or 12h and then JNK/p38 MAPK at 8 to 12h. MAPK phosphatase-1 was decreased 12 to 24h after TNFalpha administration. This may promote a sustained activation of JNK. Bax was elevated, whereas Bcl-2 and cFLIP(S/L) were lowered at 4h after administration of TNFalpha. These changes were followed by increases in caspase 8 and 3 activities and apoptosis. None of the above changes were observed when TNFalpha was administered to PY-treated CYP2E1(-/-) mice. These studies show that TNFalpha increases oxidative stress in mice with elevated CYP2E1, with subsequent activation of ASK-1 via a mechanism involving thioredoxin-ASK-1 dissociation, followed by activation of downstream MKK and MAPK. We speculate that similar interactions between CYP2E1 and TNFalpha may be important for alcohol-induced liver injury.
authors.affiliation: Department of Pharmacology and Systems Therapeutics, Mount Sinai School of Medicine, New York, NY 10029, USA.
authors.forename: Defeng
authors.initials: D
authors.lastname: Wu
authors.forename: Arthur
authors.initials: A
authors.lastname: Cederbaum
mesh_terms: D000818:Animals; D056486:Chemical and Drug Induced Liver Injury / Q000209:etiology*; D019392:Cytochrome P-450 CYP2E1 / Q000502:physiology*; D004357:Drug Synergism; D004789:Enzyme Activation; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D048371:MAP Kinase Kinase 3 / Q000378:metabolism; D048669:MAP Kinase Kinase 6 / Q000378:metabolism; D048688:MAP Kinase Kinase 7 / Q000378:metabolism; D048848:MAP Kinase Kinase Kinase 5 / Q000378:metabolism*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D011720:Pyrazoles / Q000633:toxicity; D014409:Tumor Necrosis Factor-alpha / Q000633:toxicity*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D011720:Pyrazoles; D014409:Tumor Necrosis Factor-alpha; C031280:pyrazole; D019392:Cytochrome P-450 CYP2E1; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048848:MAP Kinase Kinase Kinase 5; D048371:MAP Kinase Kinase 3; D048669:MAP Kinase Kinase 6; D048688:MAP Kinase Kinase 7; C482531:Map2k3 protein, mouse; C482567:Map2k6 protein, mouse; C482570:Map2k7 protein, mouse; D020929:Mitogen-Activated Protein Kinase Kinases