TXNIP promotes ferroptosis through NCOA4 mediated ferritinophagy

Abstract

Ferroptosis is a recently discovered lytic form of cell death that is triggered by iron-driven excessive lipid peroxidation and depletion of glutathione and glutathione peroxidase-4 (GPX4). This form of cell death has been linked to a wide range of conditions from cancer to neurodegenerative diseases. Using murine hippocampal HT22 neurons, we aimed to investigate the underlying mechanisms of glutamate-mediated ferroptosis. A robust increase in Thioredoxin-Inhibiting Protein (TXNIP) prompted us to use genetic approaches and examine the role of this protein in ferroptosis in HT22 neurons, mouse embryonic fibroblasts, and Hela cells. Our results indicate that TXNIP is a key player in ferroptotic pathway, as its deletion conferred resistance to classic ferroptosis-inducing agents (erastin, RSL3, and ML210), while TXNIP overexpression increased their susceptibility to ferroptosis. Notably, TXNIP deletion protected cells from mitochondrial dysfunction induced by ferroptotic agents, independent of GSH and GPX4 levels. We further showed that TXNIP mediates ferroptosis through facilitating degradation of the iron-binding protein ferritin via NCOA4-mediated ferritinophagy. This resulted in elevated cytosolic labile iron levels, therefore amplifying lipid peroxidation, and promoting ferroptosis. Our findings suggest that TXNIP acts as a positive regulator of ferroptosis by modulating autophagy and iron availability. Targeting TXNIP might hold promise in developing drugs for diseases involving the ferroptotic pathway.