Ferritinophagy is a specific type of autophagy that maintains intracellular iron metabolic homeostasis by targeting ferritin, one of the major forms of iron storage in the human body. Previous research has demonstrated that quercetin prevents the ferroptosis of oligodendrocyte progenitor cells (OPCs) by inhibiting the Id2/transferrin pathway. Given the ability of quercetin to suppress autophagy in spinal cord injury (SCI), this study aimed to investigate whether quercetin prevents ferroptosis in an autophagy-dependent manner. In erastin-treated OPCs, quercetin significantly upregulated the protein level of ferritin heavy chain (FTH) and markedly reduced its colocalization with LysoTracker, an indicator of lysosome aggregation. Quercetin significantly reduced the ferrous iron levels, the LC3II/LC3I ratio, and the number of LC3 puncta in OPCs, whereas it increased the level of sequestosome 1 (P62) in erastin-treated OPCs. Pretreatment of OPCs with autophagy inhibitor bafilomycin A1 inhibited quercetin-mediated ferritinophagy and ferroptosis, whereas pretreatment with autophagy activator rapamycin reversed the effect of quercetin on ferritinophagy and ferroptosis of OPCs, as evidenced by reduced protein levels of ferritin heavy chain and p62, as well as increased protein levels of LC3II/LC3I and prostaglandin-endoperoxide synthase 2 (PTGS2). Compared with the erastin and quercetin treated OPCs, increased rerrous iron, lipid peroxidation production, and decreased GSH content, as well as shrunken mitochondria, were observed in OPCs treated with a combination of erastin, quercetin, and rapamycin. In vivo, quercetin significantly downregulated the nuclear receptor coactivator 4 (NCOA4) and PTGS2 protein expression, as well as the LC3II/LC3I ratio. Besides that, quercetin reduced the MDA level and the colocalization of FTH with NCOA4 in spinal cord tissues. Mechanistically, NCOA4 reversed the effect of quercetin on ferritinophagy and ferroptosis of OPCs, whereas mutation of Y71 to alanine only slightly reversed the above effect. In conclusion, our findings revealed that quercetin inhibits OPCs ferroptosis by blocking NCOA4-mediated ferritinophagy. Quercetin and ferritinophagy may be potential therapeutic agents for SCI.
