Blocking mitochondrial Complex II shields neuron-like cells from iron-driven ferroptosis death

Ferroptosis, an iron-dependent cell death driven by runaway lipid peroxidation, is increasingly linked to neurodegeneration, ischemic injury, and other age-related conditions. Mitochondria produce both cellular energy and much of the cell's reactive oxygen species, yet their role in ferroptosis is contested. Results seem to vary with the ferroptosis inducer and the mitochondrial modulator used.

This study used SH-SY5Y neuroblastoma cells, a common neuron-like model. The researchers triggered ferroptosis with RSL3, which inhibits the antioxidant enzyme GPX4. They then tested whether blocking specific electron transport chain complexes changed the outcome, comparing the Complex II inhibitor TTFA with the Complex I inhibitor rotenone.

RSL3 raised mitochondrial membrane potential and superoxide production while lowering ATP-linked oxygen consumption. TTFA co-treatment markedly suppressed lipid peroxidation and cell death. It also reversed the hyperpolarization, lowered mitochondrial ROS, reduced proton leak, improved ATP-linked respiration, and restored ATP production. Rotenone did not reduce superoxide or lipid peroxidation, though it partially reduced RSL3 cytotoxicity.

The authors conclude that Complex II contributes to RSL3-induced oxidative stress and that inhibiting it protects by maintaining redox balance and energy metabolism. This points to the electron transport chain as a possible regulatory node in ferroptosis, and shows that different complexes are not interchangeable in this process.

Caveats are substantial. The work comes from a single cancer-derived cell line and a single ferroptosis inducer, and only the abstract was reviewed. Complex II inhibitors can be toxic, so therapeutic relevance is unproven. Findings may not generalize to other cell types, inducers, or living organisms.