Chronic Low-Dose Oxidative Stress Induces Caspase-3-Dependent PKC8 Proteolytic Activation and Apoptosis in a Cell Culture Model of Dopaminergic Neurodegeneration

Oxidative stress has been implicated as a key event in the degenerative process of dopaminergic neurons; however, the cellular mechanisms underlying chronic oxidative stress-induced neurodegeneration remain to be established. In this study, N27 cells, a dopaminergic neuronal cell line derived from rat mesencephalon, exposed to low doses of H2O2 (0-30 mu M for 12-24 hr) exhibited dose- and time-dependent increases in cytotoxicity and ROS generation. In addition, the H2O2-induced neurotoxicity was accompanied by increased caspase-3 activity and PKC delta cleavage. Notably, treatment with antioxidants Trolox and MnTBAP or PKC delta cleavage inhibitor z-DIPD-fmk significantly protected against oxidative stress-induced apoptotic cell death. These results demonstrate that the N27 cell line is a useful model for the study of the chronic low-dose oxidative stress-induced apoptotic cell death cascade and that caspase-3-dependent PKC delta proteolytic activation may be important in the apoptotic process in dopaminergic neurons undergoing chronic oxidative insult.