Ferroptosis and PANoptosis under hypoxia pivoting on the crosstalk between DHODH and GPX4 in corneal epithelium

Cell death under stress conditions like hypoxia, involves multiple interconnected pathways. In this study, a stable dihydroorotate dehydrogenase (DHODH) knockdown human corneal epithelial cell line was established to explore the regulation of hypoxic cell death, which was mitigated by various cell death inhibitors, particularly by a lipid peroxyl radical scavenger liproxstatin-1 (Lip-1), suggesting that hypoxic cell death involves crosstalk of ferroptosis and PANoptosis. We discovered that both DHODH and Glutathione peroxidase 4 (GPX4) protected cells from hypoxic death by inhibiting lipid peroxidation, mitochondrial reactive oxygen species (ROS) and maintaining mitochondrial membrane potential. However, upregulation of DHODH suppressed GPX4 upstream, exhibiting a trade-off in the expression levels between DHODH and GPX4 under hypoxia, with DHODH exerting a more decisive impact on cell survival. DHODH knockdown under hypoxia did not significantly alter lipid peroxidation levels, demonstrating the balance between DHODH and GPX4 expression finely regulated cellular ferroptosis homeostasis. This study highlights the complex interplay between ferroptosis and PANoptosis in hypoxic cell death, particularly the dual role of DHODH in regulating both pathways. DHODH is not merely maintaining the quantity of mitochondria but is promoting the selection of mitochondria favorable to cell survival. These findings not only deepen our understanding of cell death but also suggest potential therapeutic strategies for diseases involving oxidative stress and mitochondrial dysfunction.