title: Pro- and anti-apoptotic roles of c-Jun N-terminal kinase (JNK) in ethanol and acetaldehyde exposed rat hepatocytes.
abstract: We have examined the significance of the activation of c-Jun N-terminal kinase (JNK) and p42/44 mitogen-activated protein kinase (MAPK) by ethanol and acetaldehyde in rat hepatocyte apoptosis. Acetaldehyde induced rapid and transient (15 min) activation of p42/44 MAPK followed by activation of JNK, which remained above control up to 1 h. Ethanol activated JNK for up to 4 h. Both ethanol and acetaldehyde caused apoptosis as determined by DNA fragmentation, caspase-3 activation and 2'[4-ethoxyphenyl]-5-[4-methyl-piperazinyl]-2,5'-bi-1H-benzimidazole (Hoechst 33342) staining. Ethanol-induced apoptosis was blocked by JNK inhibitor 1,9-pyrazoloanthrone (SP600125), indicating that JNK activation is pro-apoptotic. In contrast, acetaldehyde-induced apoptosis was not suppressed by this inhibitor. In fact, SP600125 potentiated acetaldehyde-induced apoptosis, suggesting that JNK activation is anti-apoptotic. Inhibition of p42/44 MAPK by MAPK kinase (MKK1) inhibitor, 1,4-diamino-2,3-dicyano-1,4-bis(2-aminophenylthio)butadiene (U0126), potentiated apoptosis by acetaldehyde or ethanol, suggesting anti-apoptotic role of p42/44 MAPK. The activation of JNK by ethanol or acetaldehyde was insensitive to the genistein (tyrosine kinase inhibitor), GF109203X (2-[1-(3-dimethylaminopropyl)-1H-indol-3-yl]-3-(1H-indol-3-yl)maleimide, protein kinase C [PKC] inhibitor) and N-acetylcysteine (N-AC) (antioxidant), whereas p42/44 MAPK activation by acetaldehyde was inhibited by genistein and GF109203X. Furthermore, p42/44 MAPK activation is not necessary for the JNK activation. In summary, transient activation of JNK by acetaldehyde is anti-apoptotic, whereas sustained activation of JNK by ethanol is pro-apoptotic. The activation of p42/44 MAPK appears to be anti-apoptotic for both ethanol and acetaldehyde. Thus, JNK activation by ethanol and acetaldehyde can be both pro- and anti-apoptotic in hepatocytes.
authors.affiliation: Department of Medical Pharmacology and Physiology, School of Medicine, University of Missouri, Columbia, MO 65212, USA.
authors.forename: Youn Ju
authors.initials: YJ
authors.lastname: Lee
authors.forename: Shivendra D
authors.initials: SD
authors.lastname: Shukla
mesh_terms: D000079:Acetaldehyde / Q000494:pharmacology*; D000111:Acetylcysteine / Q000494:pharmacology; D000818:Animals; D000873:Anthracenes / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D015153:Blotting, Western; D002070:Butadienes / Q000494:pharmacology; D019328:Buthionine Sulfoximine / Q000494:pharmacology; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D053938:DNA Fragmentation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D000431:Ethanol / Q000494:pharmacology*; D019833:Genistein / Q000494:pharmacology; D022781:Hepatocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007211:Indoles / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008297:Male; D008298:Maleates / Q000494:pharmacology; D008301:Maleimides / Q000494:pharmacology; D008856:Microscopy, Fluorescence; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism; D009570:Nitriles / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D013997:Time Factors
chemical_list: D000873:Anthracenes; D002070:Butadienes; D004791:Enzyme Inhibitors; D007211:Indoles; D008298:Maleates; D008301:Maleimides; D009570:Nitriles; D017382:Reactive Oxygen Species; C113580:U 0126; C432165:pyrazolanthrone; D000431:Ethanol; D019328:Buthionine Sulfoximine; D006861:Hydrogen Peroxide; D019833:Genistein; D048031:JNK Mitogen-Activated Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases; C014476:diethyl maleate; D000079:Acetaldehyde; C070515:bisindolylmaleimide I; D000111:Acetylcysteine