Oxidative stress is a well-known inducer of neuronal apoptosis and axonal degeneration. We previously showed that the E3 ubiquitin ligase ZNRF1 promotes Wallerian degeneration by degrading AKT to induce GSK3B activation. We now demonstrate that oxidative stress serves as an activator of the ubiquitin ligase activity of ZNRF1 by inducing epidermal growth factor receptor (EGFR)-mediated phosphorylation at the 103rd tyrosine residue and that the up-regulation of ZNRF1 activity by oxidative stress leads to neuronal apoptosis and Wallerian degeneration. We also show that nicotinamide adenine dinucleotide phosphate-reduced oxidase activity is required for the EGFR-dependent phosphorylation-induced activation of ZNRF1 and resultant AKT degradation via the ubiquitin proteasome system to induce Wallerian degeneration. These results indicate the pathophysiological significance of the EGFR-ZNRF1 pathway induced by oxidative stress in the regulation of neuronal apoptosis and Wallerian degeneration. A deeper understanding of the regulatory mechanism for ZNRF1 catalytic activity via phosphorylation will provide a potential therapeutic avenue for neurodegeneration.
© 2015 Wakatsuki et al.