Glutaredoxin protects cerebellar granule neurons from dopamine-induced apoptosis by dual activation of the Ras-phosphoinositide 3-kinase and jun N-terminal kinase pathways

Glutaredoxin 2 (Grx2) from Escherichia coli protects cerebellar neurons fro m dopamine-induced apoptosis via nuclear factor kappa B (NF-kappaB) activat ion, which is mediated by the expression of redox factor-1 (Ref-1), An anal ysis of the mechanisms underlying Grx2 protective activity revealed dual ac tivation of signal transduction pathways. Grx2 significantly activated the Ras/phosphoinositide 3-kinase/Akt/NF-kappaB cascade in parallel to the Jun N-terminal kinase (JNK)/AP1 cascade. Dopamine, in comparison, down-regulate d both pathways. Treatment of neurons with Ref-1 antisense oligonucleotide reduced the ability of Grx2 to activate Akt and AP-1 but had no effect on t he phosphorylation of JNK1/2, suggesting that Akt/NF-kappaB and AP-1 are re gulated by Ref-1. Exposure of the neurons to JNK1/2 antisense oligonucleoti de in the presence of Grx2 significantly reduced AP-1 and NF-kappaB DNA bin ding activities and abolished Grx2 protection. These results demonstrate th at dual activation of Ras/phosphoinositide 3-kinase and AP-1 cascades, whic h are mediated by Ref-1, is an essential component of the Grx2 mechanism of action.