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Modulation of pro-survival Akt/protein kinase B and ERK1/2 signaling cascades by quercetin and its in vivo metabolites underlie their action on neuronal viability

Spencer, J., Rice-Evans, C. and Williams, R.J. (2003) Modulation of pro-survival Akt/protein kinase B and ERK1/2 signaling cascades by quercetin and its in vivo metabolites underlie their action on neuronal viability. The Journal of Biological Chemistry, 278 (37). pp. 34783-34793. ISSN 1083-351X

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To link to this item DOI: 10.1074/jbc.M305063200


Much recent interest has focused on the potential of flavonoids to interact with intracellular signaling pathways such as with the mitogen-activated protein kinase cascade. We have investigated whether the observed strong neurotoxic potential of quercetin in primary cortical neurons may occur via specific and sensitive interactions within neuronal mitogen-activated protein kinase and Akt/protein kinase B (PKB) signaling cascades, both implicated in neuronal apoptosis. Quercetin induced potent inhibition of both Akt/PKB and ERK phosphorylation, resulting in reduced phosphorylation of BAD and a strong activation of caspase-3. High quercetin concentrations (30 microM) led to sustained loss of Akt phosphorylation and subsequent Akt cleavage by caspase-3, whereas at lower concentrations (<10 microM) the inhibition of Akt phosphorylation was transient and eventually returned to basal levels. Lower levels of quercetin also induced strong activation of the pro-survival transcription factor cAMP-responsive element-binding protein, although this did not prevent neuronal damage. O-Methylated quercetin metabolites inhibited Akt/PKB to lesser extent and did not induce such strong activation of caspase-3, which was reflected in the lower amount of damage they inflicted on neurons. In contrast, neither quercetin nor its O-methylated metabolites had any measurable effect on c-Jun N-terminal kinase phosphorylation. The glucuronide of quercetin was not toxic and did not evoke any alterations in neuronal signaling, probably reflecting its inability to enter neurons. Together these data suggest that quercetin and to a lesser extent its O-methylated metabolites may induce neuronal death via a mechanism involving an inhibition of neuronal survival signaling through the inhibition of both Akt/PKB and ERK rather than by an activation of the c-Jun N-terminal kinase-mediated death pathway.

Item Type:Article
Divisions:Life Sciences > School of Chemistry, Food and Pharmacy > Department of Food and Nutritional Sciences > Human Nutrition Research Group
ID Code:18615
Uncontrolled Keywords:Animals Cell Survival/drug effects Cells, Cultured Cerebral Cortex/physiology Kinetics MAP Kinase Signaling System/drug effects/*physiology Mice Mitogen-Activated Protein Kinase 1/metabolism Mitogen-Activated Protein Kinase 3 Mitogen-Activated Protein Kinases/metabolism Neurons/*cytology/drug effects/*physiology Phosphorylation Protein-Serine-Threonine Kinases/metabolism Proto-Oncogene Proteins/*metabolism Proto-Oncogene Proteins c-akt Quercetin/pharmacokinetics/*pharmacology
Additional Information:Spencer, Jeremy P E Rice-Evans, Catherine Williams, Robert J Research Support, Non-U.S. Gov't United States The Journal of biological chemistry J Biol Chem. 2003 Sep 12;278(37):34783-93. Epub 2003 Jun 24.
Publisher:American Society for Biochemistry and Molecular Biology

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