Proteomic analysis of carbonylated proteins in the monkey substantia nigra after ischemia-reperfusion

In Parkinson's disease (PD), oxidative stresses cause cell death of dopaminergic neurons of the substantia nigra (SN), but its molecular mechanism still remains unclarified. Our previous study of proteomic analysis in the monkey CA1 hippocampus after ischemia-reperfusion revealed reactive oxygen species (ROS)-induced carbonyl modification of a molecular chaperone, heat shock 70-kDa protein 1 (Hsp70.1), especially in its key site, Arg469. Here, to clarify the mechanism of neurodegeneration in PD, the SN tissue of the same monkey experimental paradigm was studied for identifying and characterizing carbonylated proteins by the two-dimensional gel electrophoresis with immunochemical detection of protein carbonyls (2D Oxyblot). We found carbonyl modification not only of Hsp70.1 but also of mitochondrial aconitase, dihydropyrimidinase-related protein 2, T-complex protein 1 subunit alpha, dihydrolipoyl dehydrogenase, fructose-bisphosphate aldolase C, glutamate dehydrogenase 1, and aspartate aminotransferase. Intriguingly, in the SN also, the carbonylation site of Hsp70.1 was identified to be Arg469. Since Hsp70.1 is recently known to stabilize the lysosomal membrane, its oxidative injury conceivably plays an important role in the ROS-mediated neuronal cell death by inducing lysosomal destabilization. Implications of each carbonylated proteins for the dopaminergic neuronal death were discussed, in comparison with the CA1 neuronal death.