Redox homeostasis in ferroptosis and aging: a causal role for fard-1 and dhs-25 in Caenorhabditis elegans

Aging is a natural process characterized by a progressive physiological decline that undermines health and well-being in the elderly population. Oxidative stress is a widely accepted hallmarks of aging, and its role as one of the main drivers of ferroptosis is quite recent. Ferroptosis is an iron-dependent cell death caused by massive phospholipid peroxidation. The excessive accumulation of intracellular reactive oxygen species and iron, as well as the failure of the main cellular antioxidant systems, cause ferroptotic cell death. While clear roles for ferroptosis in pathological conditions such as cancer or neurodegeneration have been described, its physiological roles and regulators are less understood. Here, using Caenorhabditis elegans as a powerful model organism for aging studies, we uncover a role for ferroptosis in physiological aging mediated by disturbed redox homeostasis. We evaluated healthspan parameters in C. elegans highlighting how several age-related features differentially decline during physiological aging. A progressive loss of the capability to contrast external stressors, with an increase in hydroxyl radicals and a decrease of glutathione demonstrated the disruption of redox homeostasis in older age. Moreover, transcription of selected genes involved in redox metabolism is downregulated with aging. Among them, loss of the fatty acyl-CoA reductase encoded by fard-1 and of the dehydrogenase encoded by dhs-25 display higher sensitivity to ferroptosis, increased lipid peroxidation, lower total glutathione levels and reduced lifespan. Accordingly, the expression of hydroxysteroid 17-beta dehydrogenase 8, one of the closest mammalians dhs-25 homologs, is downregulated in cells which are more sensitive to ferroptosis. Our results clearly prove a causal role for ferroptosis in C. elegans aging driven by mitochondrial redox unbalance, unveiling novel genes involved in this connection that may constitute targets for possible interventions to improve healthy aging.