title: 6-Hydroxydopamine induces mitochondrial ERK activation.
abstract: Reactive oxygen species (ROS) are implicated in 6-hydroxydopamine (6-OHDA) injury to catecholaminergic neurons; however, the mechanism(s) are unclear. In addition to ROS generated during autoxidation, 6-OHDA may initiate secondary cellular sources of ROS that contribute to toxicity. Using a neuronal cell line, we found that catalytic metalloporphyrin antioxidants conferred protection if added 1 h after exposure to 6-OHDA, whereas the hydrogen peroxide scavenger catalase failed to protect if added more than 15 min after 6-OHDA. There was a temporal correspondence between loss of protection and loss of the ability of the antioxidant to inhibit 6-OHDA-induced ERK phosphorylation. Time course studies of aconitase inactivation, an indicator of intracellular superoxide, and MitoSOX red, a mitochondria targeted ROS indicator, demonstrate early intracellular ROS followed by a delayed phase of mitochondrial ROS production, associated with phosphorylation of a mitochondrial pool of ERK. Furthermore, on initiation of mitochondrial ROS and ERK activation, 6-OHDA-injured cells became refractory to rescue by metalloporphyrin antioxidants. Together with previous studies showing that inhibition of the ERK pathway confers protection from 6-OHDA toxicity, and that phosphorylated ERK accumulates in mitochondria of degenerating human Parkinson's disease neurons, these studies implicate mitochondrial ERK activation in Parkinsonian oxidative neuronal injury.
authors.affiliation: Department of Pathology, VA Pittsburgh Healthcare System, Pittsburgh, PA 15240, USA. kulichsm@upmc.edu
authors.forename: Scott M
authors.initials: SM
authors.lastname: Kulich
authors.forename: Craig
authors.initials: C
authors.lastname: Horbinski
authors.forename: Manisha
authors.initials: M
authors.lastname: Patel
authors.forename: Charleen T
authors.initials: CT
authors.lastname: Chu
mesh_terms: D000818:Animals; D002070:Butadienes / Q000494:pharmacology; D002374:Catalase / Q000494:pharmacology; D002478:Cells, Cultured; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000502:physiology*; D005419:Flavonoids / Q000494:pharmacology; D008665:Metalloporphyrins / Q000494:pharmacology; D008928:Mitochondria / Q000187:drug effects* / Q000502:physiology; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors; D009474:Neurons / Q000187:drug effects; D009570:Nitriles / Q000494:pharmacology; D016627:Oxidopamine / Q000494:pharmacology* / Q000633:toxicity; D051381:Rats; D015398:Signal Transduction
chemical_list: D002070:Butadienes; D005419:Flavonoids; D008665:Metalloporphyrins; D009570:Nitriles; C113580:U 0126; C431023:manganese (III) meso-tetrakis(N-ethylpyridinium-2-yl)porphyrin; C097284:manganese(III)-tetrakis(4-benzoic acid)porphyrin; D016627:Oxidopamine; D002374:Catalase; D048049:Extracellular Signal-Regulated MAP Kinases; D020929:Mitogen-Activated Protein Kinase Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one