Apoptotic signaling in dopamine-induced cell death: the role of oxidative stress, p38 mitogen-activated protein kinase, cytochrome c and caspases.
Oxidative stress generated by dopamine (DA) oxidation could be one of the factors underlying the selective vulnerability of nigral dopaminergic neurons in Parkinson's diseases. Here we show that DA induces apoptosis in SH-SY5Y neuroblastoma cells demonstrated by activation of caspase-9 and caspase-3, cleavage of poly(ADP-ribose) polymerase as well as nuclear condensation. We also show that p38 mitogen-activated protein kinase is activated within 10 min of DA treatment, which precedes the onset of apoptosis because the potent p38 kinase inhibitor SB203580 protects against DA-induced cell death as well as against caspase-9 and caspase-3 activation. In addition, the antioxidant N-acetyl-L-cysteine (NAC) effectively blocks DA-induced p38 kinase activation, caspase-9 and caspase-3 cleavage and subsequent apoptosis, indicating that DA triggers apoptosis via a signaling pathway that is initiated by the generation of reactive oxygen species (ROS). Dopamine exerts its toxicity principally intracellularly as the DA uptake inhibitor, nomifensine significantly reduces DA-induced cell death as well as activation of p38 kinase and caspase-3. Furthermore, DA induces mitochondrial cytochrome c release, which is dependent on p38 kinase activation and precedes the cleavage of caspases. These observations indicate that DA induces apoptosis primarily by generating ROS, p38 kinase activation, cytochrome c release followed by caspase-9 and caspase-3 activation.
Junn
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Genetic Pharmacology Unit, Experimental Therapeutics Branch, NINDS, National Institutes of Health, Bethesda, Maryland, USA.
Mouradian
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MM
D000111:Acetylcysteine / Q000494:pharmacology; D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D001692:Biological Transport; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism*; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D003574:Cytochrome c Group / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D007700:Kinetics; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009447:Neuroblastoma; D009627:Nomifensine / Q000494:pharmacology; D018384:Oxidative Stress / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D014407:Tumor Cells, Cultured; D048051:p38 Mitogen-Activated Protein Kinases
D000590:Amino Acid Chloromethyl Ketones; D015853:Cysteine Proteinase Inhibitors; D003574:Cytochrome c Group; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D009627:Nomifensine; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C505407:CASP3 protein, human; C506433:CASP9 protein, human; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases; D004298:Dopamine; D000111:Acetylcysteine