Induction of Neurite Outgrowth in PC12 Cells by α -Phenyl-N-tert-butylnitron through Activation of Protein Kinase C and the Ras-Extracellular Signal-regulated Kinase Pathway

Abstract

The spin trap α-phenyl-N-tert-butylnitron (PBN) is widely used for studies of the biological effects of free radicals. We previously reported the protective effects of PBN against ischemia-reperfusion injury in gerbil hippocampus by its activation of extracellular signal-regulated kinase (ERK) and suppression of both stress-activated protein kinase and p38 mitogen-activated protein kinase. In the present study, we found that PBN induced neurite outgrowth accompanied by ERK activation in PC12 cells in a dose-dependent manner. The induction of neurite outgrowth was inhibited significantly not only by transient transfection of PC12 cells with dominant negative Ras, but also by treatment with mitogen-activated protein kinase/ERK kinase inhibitor PD98059. The activation of receptor tyrosine kinase TrkA was not involved in PBN-induced neurite out-growth. A protein kinase C (PKC) inhibitor, GF109203X, was found to inhibit neurite outgrowth. The activation of PKCε was observed after PBN stimulation. PBN-induced neurite outgrowth and ERK activation were counteracted by the thiol-based antioxidant N-acetyl-cysteine. From these results, it was concluded that PBN induced neurite outgrowth in PC12 cells through activation of the Ras-ERK pathway and PKC.