The role of NF-κB in 6-hydroxydopamine- and TNFα-induced apoptosis of PC12 cells

6-Hydroxydopamine (6-OHDA) is widely used to study the death of catecholaminergic cells related to Parkinson's disease. Oxidative stress and gene transcription are known to mediate the pro-apoptotic effect of 6-OHDA. As redox mechanisms are involved in activation of the transcription factor NF-κB, we studied the role of NF-κB in 6-OHDA-induced death of PC12 cells. We stably transfected PC12 cells with a doxycycline-regulated expression vector for the NF-KB super-repressor (IκBα mutated at serine-32 and serine-36, IκBα-SR). NF-κB transcriptional activity was evaluated by transient transfection of an NF-κB-driven luciferase reporter gene. Expression of IκBα-SR inhibited NF-κB stimulated by tumor necrosis factor α (TNFα) and 6-OHDA. Apoptosis was quantified by counting cells with condensed nuclei. IκBα-SR inhibited apoptosis induced by 6-OHDA but enhanced apoptosis that was triggered by TNFα. The converse effects of NF-κB could be due to different target genes that are induced in the context of TNFα and 6-OHDA stimulation. Indeed, TNFα stimulated mRNA accumulation of the anti-apoptotic superoxide dismutase 2 through NF-κB whereas 6-OHDA induced mRNA accumulation of the proapoptotic c-myc. These data demonstrate that NF-κB regulates survival of the neuron-like PC12 cells in a stimulus-specific manner. In the context of 6-OHDA stimulation, NF-κB mediates pro-apoptotic effects, suggesting that NF-κB signaling could be a target for drug development in Parkinson-related neurodegeneration.