LAUSR

As a systemic syndrome characterized by age-associated degenerative skeletal muscle atrophy, sarcopenia leads to a risk of adverse outcomes in the elderly. Age-related iron accumulation is found in the muscles of sarcopenia animal models and patients, but the role of iron in sarcopenia remains poorly understood. It has been recently found that iron overload in several diseases is involved in ferroptosis, an iron- dependent form of programmed cell death. However, whether this excess iron can result in ferroptosis in muscles is still unclear. In our present study, we found that ferric citrate induced ferroptosis in C2C12 cells, as well as impaired their differentiation from myoblasts to myotubes. Due to the decreased muscle mass and fiber size, 40-week-old senescence accelerated mouse prone 8 (SAMP8) mice were used as a sarcopenia model, in whose muscles the iron content and markers of ferroptosis were found to increase, compared to 8-week- old SAMP8 controls. Moreover, our results showed that iron overload upregulated the expression of P53, which subsequently repressed the protein level of Slc7a11 (solute carrier family 7, member 11), a known ferroptosis-related gene. The downregulation of Slc7a11 then induced the ferroptosis of muscle cells through the accumulation of lipid peroxidation products, which may be one of the causes of sarcopenia. The findings in this study indicate that iron plays a key role in triggering P53- Slc7a11-mediated ferroptosis in muscles, and suggest that targeting iron accumulation and ferroptosis might be a therapeutic strategy for treating sarcopenia.