Methylmercury induces ferroptosis by suppressing GPX4 protein levels in C17.2 mouse neural stem cells.

The causative agent of Minamata disease, which is characterized primarily by severe central nervous system dysfunction, is methylmercury; however, the mechanisms underlying methylmercury toxicity remain unclear. Ferroptosis is a type of programmed cell death that is mediated by iron-dependent lipid peroxidation and methylmercury has long been suggested to cause neuronal damage via lipid peroxidation, although the detailed mechanism of this action remains unknown. In this study we therefore investigated the involvement of ferroptosis in methylmercury-induced neuronal cell death using C17.2 mouse neural stem cells. First, we examined the effects of various ferroptosis inhibitors (ferrostatin-1, liproxstatin-1, and deferoxamine) on methylmercury-induced cell death. All the inhibitors tested attenuated methylmercury-induced cell death. We then examined the levels of intracellular reactive oxygen species and lipid peroxides, and found that these levels were increased prior to methylmercury-induced cell death. We also examined the levels of a cystine transporter (xCT/SLC7A11) and glutathione peroxidase 4 (GPX4), major factors involved in the suppression of ferroptosis. We found that both mRNA and protein levels of xCT were increased prior to methylmercury-induced cell death, whereas GPX4 mRNA levels were largely unaffected by methylmercury and its protein levels were decreased. C17.2 cells overexpressing FLAG-GPX4 exhibited greater resistance to methylmercury than control cells. These results indicate that methylmercury induces ferroptosis in C17.2 cells by suppressing GPX4 protein levels.