The aim of this study was to investigate changes in protein profiles during the early phase of dopaminergic neuronal death using two-dimensional gel electrophoresis in conjunction with mass spectrometry. Several protein spots were identified whose expression was significantly altered following treatment of MN9D dopaminergic neuronal cells with 6-hydroxydopamine (6-OHDA). In particular, we detected oxidative modification of thioredoxin-dependent peroxidases (peroxiredoxins; PRX) in treated MN9D cells. Oxidative modification of PRX induced by 6-OHDA was blocked in the presence of N-acetylcysteine, suggesting that reactive oxygen species (ROS) generated by 6-OHDA induce oxidation of PRX. These findings were confirmed in primary cultures of mesencephalic neurons and in rat brain injected stereotaxically. Overexpression of PRX1 in MN9D cells (MN9D/PRX1) exerted neuroprotective effects against death induced by 6-OHDA through scavenging of ROS. Consequently, generation of both superoxide anion and hydrogen peroxide following 6-OHDA treatment was decreased in MN9D/PRX1. Furthermore, overexpression of PRX1 protected cells against 6-OHDA-induced activation of p38 MAPK and subsequent activation of caspase-3. In contrast, 6-OHDA-induced apoptotic death signals were enhanced by RNA interference-targeted reduction of PRX1 in MN9D cells. Taken together, our data suggest that the redox state of PRX may be intimately involved in 6-OHDA-induced dopaminergic neuronal cell death and also provide a molecular mechanism by which PRX1 exerts a protective role in experimental models of Parkinson disease. Parkinson disease (PD)3 is a common neurodegenerative disorder characterized by progressive degeneration of dopaminergic (DA) neurons in the substantia nigra pars compacta (1). Clinical manifestations, such as resting tremor, slowness of movement, stiffness, and postural instability in patients with PD are consequences of the loss of DA neurons and the resulting depletion of dopamine in the striatum. Most PD cases are sporadic, and its etiology is incompletely understood; however, an increasing body of evidence suggests that oxidative stress, mitochondrial dysfunction, and impairment of the ubiquitinproteasome system may be involved in the pathogenesis of PD (2-5). Recent studies indicate that mutations in several genes appear to cause a familial form of PD (6), and mutations in these genes seem to share common pathways underlying the pathogenesis of a sporadic form of PD.DA neurons are vulnerable to neurodegeneration because of their high levels of reactive oxygen species (ROS) (7); enzymatic metabolism of dopamine produces hydrogen peroxide and superoxide radicals, and intracellular autoxidation of dopamine induces the formation of dopamine-quinone, leading to the generation of hydroxyl radical when combined with iron (7, 8). Furthermore, there is a significant alteration in levels or activities of antioxidant enzymes in the substantia nigra (9 -13). Among many potential consequences of oxidative stress, surges in ROS render DA neuron...

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Background: It is crucial to identify caspase-3 substrates and their roles during neurodegeneration. Results: Our approach identified 46 novel substrates. Furthermore, we found that anamorsin was cleaved by caspase-3 and mapped its cleavage site. Conclusion: Anamorsin may play an antiapoptotic role in the central nervous system. Significance: Our findings contribute to understanding the molecular mechanism underlying role for anamorsin in caspase-3-mediated cell death.