Anti-apoptotic effect of quercetin: intervention in the JNK- and ERK-mediated apoptotic pathways.
BACKGROUND
Bioflavonoid quercetin inhibits hydrogen peroxide (H2O2)-induced apoptosis via intervention in the activator protein 1 (AP-1)-mediated apoptotic pathway. In this report, we investigated molecular events involved in the anti-apoptotic effect of quercetin, focusing especially on its effects on the family of mitogen-activated protein (MAP) kinases.


METHODS
Cultured mesangial cells were exposed to H2O2, and activation of c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinases (ERKs), and p38 MAP kinase was evaluated in the presence or absence of quercetin. Using pharmacological and genetic inhibitors, the roles for individual MAP kinases in H2O2-induced apoptosis were examined. Involvement of ERKs in the induction and activation of AP-1 was also investigated using Northern blot analysis and a reporter assay.


RESULTS
Mesangial cells exposed to H2O2 exhibited rapid phosphorylation of JNK, ERKs, and p38 MAP kinase. Quercetin abrogated the activation of all three MAP kinases in response to H2O2. Pretreatment with MAP kinase kinase inhibitor PD098059 or JNK-c-Jun/AP-1 inhibitor curcumin attenuated the H2O2-induced apoptosis. In contrast, the p38 MAP kinase inhibitor SB203580 did not improve the cell survival. Consistently, transfection with dominant-negative mutants of ERK1 and ERK2 or a dominant-negative mutant of JNK inhibited H2O2-induced apoptosis. Transfection with a dominant-negative p38 MAP kinase did not attenuate the apoptotic process. Inhibition of ERKs by PD098059 suppressed induction of c-fos without affecting early induction of c-jun, leading to attenuated activation of AP-1 in response to H2O2.


CONCLUSIONS
These results suggested that (1) activation of JNK and ERKs, but not p38 kinase, is required for the H2O2-induced apoptosis; and (2) suppression of the JNK-c-Jun/AP-1 pathway and the ERK-c-Fos/AP-1 pathway is involved in the anti-apoptotic effect of quercetin.
Ishikawa
Y
Y
Department of Medicine, University College Medical School, University College London, The Rayne Institute, London, England, United Kingdom.
Kitamura
M
M
D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D002478:Cells, Cultured; D003474:Curcumin / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic; D005920:Glomerular Mesangium / Q000166:cytology* / Q000201:enzymology; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D016296:Mutagenesis / Q000502:physiology; D016877:Oxidants / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics; D011725:Pyridines / Q000494:pharmacology; D011794:Quercetin / Q000494:pharmacology*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014162:Transfection; D048051:p38 Mitogen-Activated Protein Kinases
D004791:Enzyme Inhibitors; D005419:Flavonoids; D007093:Imidazoles; D016877:Oxidants; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D011725:Pyridines; D012333:RNA, Messenger; D018808:Transcription Factor AP-1; D011794:Quercetin; D006861:Hydrogen Peroxide; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D003474:Curcumin; C093642:SB 203580; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one