Phosphorylation of p38 MAPK induced by oxidative stress is linked to activation of both caspase-8- and -9-mediated apoptotic pathways in dopaminergic neurons.
We evaluated the contribution of p38 mitogen-activated protein kinase and the events upstream/downstream of p38 leading to dopaminergic neuronal death. We utilized MN9D cells and primary cultures of mesencephalic neurons treated with 6-hydroxydopamine. Phosphorylation of p38 preceded apoptosis and was sustained in 6-hydroxydopamine-treated MN9D cells. Co-treatment with PD169316 (an inhibitor of p38) or expression of a dominant negative p38 was neuroprotective in death induced by 6-hydroxydopamine. The superoxide dismutase mimetic and the nitric oxide chelator blocked 6-hydroxydopamine-induced phosphorylation of p38, suggesting a role for superoxide anion and nitric oxide in eliciting a neurotoxic signal by activating p38. Following 6-hydroxydopamine treatment, inhibition of p38 prevented both caspase-8- and -9-mediated apoptotic pathways as well as generation of truncated Bid. Consequently, 6-hydroxydopamine-induced cell death was rescued by blockading activation of caspase-8 and -9. In primary cultures of mesencephalic neurons, the phosphorylation of p38 similarly appeared in tyrosine hydroxylase-positive, dopaminergic neurons after 6-hydroxydopamine treatment. This neurotoxin-induced phosphorylation of p38 was inhibited in the presence of superoxide dismutase mimetic or nitric oxide chelator. Co-treatment with PD169316 deterred 6-hydroxydopamine-induced loss of dopaminergic neurons and activation of caspase-3 in these neurons. Furthermore, inhibition of caspase-8 and -9 significantly rescued 6-hydroxydopamine-induced loss of dopaminergic neurons. Taken together, our data suggest that superoxide anion and nitric oxide induced by 6-hydroxydopamine initiate the p38 signal pathway leading to activation of both mitochondrial and extramitochondrial apoptotic pathways in our culture models of Parkinson's disease.
Department of Biology and Protein Network Research Center, Yonsei University College of Science, 134 Shinchon-dong, Seodaemoon-Gu, Seoul 120-749, Korea.
Won-Seok
WS
Choi
Dae-Seok
DS
Eom
Baek S
BS
Han
Won K
WK
Kim
Byung H
BH
Han
Eui-Ju
EJ
Choi
Tae H
TH
Oh
George J
GJ
Markelonis
Jin W
JW
Cho
Young J
YJ
Oh
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis; D051023:BH3 Interacting Domain Death Agonist Protein; D002352:Carrier Proteins / Q000378:metabolism; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism*; D016923:Cell Death; D002460:Cell Line; D002470:Cell Survival; D002478:Cells, Cultured; D002614:Chelating Agents / Q000494:pharmacology; D004298:Dopamine / Q000378:metabolism*; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005799:Genes, Dominant; D007093:Imidazoles / Q000494:pharmacology; D015151:Immunoblotting; D007150:Immunohistochemistry; D051379:Mice; D008928:Mitochondria / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism; D018384:Oxidative Stress; D016627:Oxidopamine / Q000494:pharmacology; D010766:Phosphorylation; D051381:Rats; D017382:Reactive Oxygen Species; D013482:Superoxide Dismutase / Q000378:metabolism; D013997:Time Factors; D014443:Tyrosine / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases
D000975:Antioxidants; D051023:BH3 Interacting Domain Death Agonist Protein; C494815:Bid protein, mouse; C494816:Bid protein, rat; D002352:Carrier Proteins; D002614:Chelating Agents; D004791:Enzyme Inhibitors; D007093:Imidazoles; D017382:Reactive Oxygen Species; D009569:Nitric Oxide; D014443:Tyrosine; D016627:Oxidopamine; D013482:Superoxide Dismutase; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C505409:Casp3 protein, mouse; C505410:Casp3 protein, rat; C505526:Casp8 protein, mouse; C505528:Casp8 protein, rat; C506434:Casp9 protein, mouse; C506435:Casp9 protein, rat; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases; C408604:2-(4-nitrophenyl)-4-(4-fluorophenyl)-5-(4-pyridinyl)-1H-imidazole; D004298:Dopamine