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.
Choi
Won-Seok
WS
Department of Biology and Protein Network Research Center, Yonsei University College of Science, 134 Shinchon-dong, Seodaemoon-Gu, Seoul 120-749, Korea.
Eom
Dae-Seok
DS
Han
Baek S
BS
Kim
Won K
WK
Han
Byung H
BH
Choi
Eui-Ju
EJ
Oh
Tae H
TH
Markelonis
George J
GJ
Cho
Jin W
JW
Oh
Young J
YJ
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