Signal transduction pathway in copper-induced apoptosis of primary cultured rat cortical neuron

Abstract

Objective To investigate copper-induced apoptosis of primary cultured rat cortical neurons and the protective effect of thioredoxin,an apoptosis signal regulated kinase-1(ASK1)inhibitor,and explore the role of ASK1-mediated c-Jun N-terminal kinase(JNK)/caspase-3 signaling pathway in the neurotoxicity of copper.Methods The changes in the viability and apoptosis of primary cultured rat neurons following exposure to cupric acetate and thoredoxin were assessed using MTT assay and flow cytometry.Western blotting was used to detect the expressions of phosphorylated ASK1(p-ASK1),p-JNKand caspase-3 in the exposed cells.Results Administration of cupric acetate in the cell culture resulted in a concentration-dependent increase of cell apoptosis and a reduction of the viability of the neurons,and the effect was antagonized by thoredoxin.The expression of p-ASK1 and p-JNK began to increase in the neurons at 4h after cupric acetate exposure,and reached the peak level at 48h,showing a time-and concentration-dependent pattern of the changes.Activated caspase-3 was expressed at 24h after the exposure,and the peak expression occurred at 48h.The application of thoredoxin significantly lowered the expressions of p-ASK1,p-JNK and caspase-3,and increased the viability and reduced the apoptotic rate in the exposed neurons(P＜0.05).Conclusions Copper can induce apoptosis of primary cultured rat cortical neurons,in which process ASK1-mediated JNK/caspase-3 signaling pathway may play a critical role.Thoredoxin can protect the cortical neurons from injuries induced by the copper. Key words: Wilson disease; C-Jun N-terminal kinase; Apoptosis signal regulated kinase-1