title: Cytoplasmic retention of peroxide-activated ERK provides survival in primary cultures of rat hepatocytes.
abstract: Reactive oxygen species (ROS) are implicated in tissue damage causing primary hepatic dysfunction following ischemia/reperfusion injury and during inflammatory liver diseases. A potential role of extracellular signal-regulated kinase (ERK) as a mediator of survival signals during oxidative stress was investigated in primary cultures of hepatocytes exposed to ROS. Hydrogen peroxide (H(2)O(2)) induced a dose-dependent activation of ERK, which was dependent on MEK activation. The ERK activation pattern was transient compared with the ERK activation seen after stimulation with epidermal growth factor (EGF). Nuclear accumulation of ERK was found after EGF stimulation, but not after H(2)O(2) exposure. A slow import/rapid export mechanism was excluded through the use of leptomycin B, an inhibitor of nuclear export sequence-dependent nuclear export. Reduced survival of hepatocytes during ROS exposure was observed when ERK activation was inhibited. Ribosomal S6 kinase (RSK), a cytoplasmic ERK substrate involved in cell survival, was activated and located in the nucleus of H(2)O(2)-exposed hepatocytes. The activation was abolished when ERK was inhibited with U0126. In conclusion, our results indicate that activity of ERK in the cytoplasm is important for survival during oxidative stress in hepatocytes and that RSK is activated downstream of ERK. Supplementary material for this article can be found on the HEPATOLOGY website (http://www.interscience.wiley.com/jpages/0270-9139/suppmat/index.html).
authors.affiliation: Laboratory for Toxicopathology, Institute of Pathology, Rikshospitalet University Hospital, Norway.
authors.forename: Carola M
authors.initials: CM
authors.lastname: Rosseland
authors.forename: Lene
authors.initials: L
authors.lastname: Wierød
authors.forename: Morten P
authors.initials: MP
authors.lastname: Oksvold
authors.forename: Heidi
authors.initials: H
authors.lastname: Werner
authors.forename: Anne Carine
authors.initials: AC
authors.lastname: Ostvold
authors.forename: G Hege
authors.initials: GH
authors.lastname: Thoresen
authors.forename: Ragnhild E
authors.initials: RE
authors.lastname: Paulsen
authors.forename: Henrik S
authors.initials: HS
authors.lastname: Huitfeldt
authors.forename: Ellen
authors.initials: E
authors.lastname: Skarpen
mesh_terms: D000818:Animals; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D003593:Cytoplasm; D048049:Extracellular Signal-Regulated MAP Kinases / Q000187:drug effects*; D022781:Hepatocytes / Q000187:drug effects* / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D008297:Male; D023421:Models, Animal; D016877:Oxidants / Q000494:pharmacology*; D018384:Oxidative Stress; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species; D038744:Ribosomal Protein S6 Kinases, 90-kDa / Q000187:drug effects* / Q000378:metabolism
chemical_list: D016877:Oxidants; D017382:Reactive Oxygen Species; D006861:Hydrogen Peroxide; D038744:Ribosomal Protein S6 Kinases, 90-kDa; D048049:Extracellular Signal-Regulated MAP Kinases