Title : Mitochondrial Calcium Uptake 1 Regulates Iron Overload-Induced Ferroptosis in H9c2 Cardiomyoblasts
Abstract:
Ischemic heart disease is a major cause of morbidity and mortality and results from insufficient coronary blood supply, leading to myocardial ischemia and cardiomyocyte death. Although reperfusion therapy restores oxygen delivery, it can exacerbate myocardial injury through oxidative stress, calcium overload, mitochondrial dysfunction, inflammation, and regulated cell death. Accumulating evidence suggests that iron dysregulation plays an important role in both ischemic heart disease and reperfusion-induced injury. Increased labile iron can promote reactive oxygen species (ROS) generation through iron-dependent redox reactions, thereby enhancing lipid peroxidation and oxidative membrane damage. Ferroptosis, an iron-dependent form of regulated cell death characterized by glutathione depletion, glutathione peroxidase 4 (GPX4) inactivation, and lipid peroxide accumulation, has emerged as a key mechanism contributing to cardiomyocyte loss and cardiovascular injury. Iron overload is particularly harmful to the heart because cardiomyocytes rely heavily on mitochondrial metabolism and are highly susceptible to oxidative damage. Under iron-overload conditions, mitochondrial iron accumulation may disrupt electron transport, increase mitochondrial ROS production, and amplify lipid peroxidation, thereby promoting ferroptotic myocardial damage. Mitochondrial calcium uptake 1 (MICU1), a key regulator of the mitochondrial calcium uniporter complex, MICU1 may critically regulate mitochondrial iron-mediated ferroptosis. Therefore, this study aimed to investigate the role of MICU1 in iron-dependent ferroptotic injury. Here, ferric ammonium citrate (FAC) was used to induce iron overload in H9c2 cardiomyoblasts. Flow cytometry showed that FAC increased intracellular and mitochondrial iron accumulation, ROS production, lipid peroxidation, and mitochondrial depolarization. MTT assay revealed that FAC reduced cell viability, while Western blotting showed decreased GPX4 protein level, indicating ferroptotic injury. Co-treatment with MCUi4, a MICU1 inhibitor, suppressed FAC-induced iron accumulation, cell death, oxidative stress, lipid peroxidation, and mitochondrial dysfunction, while restoring GPX4 protein level. These findings suggest that MICU1 contributes to iron overload-induced ferroptosis and may represent a potential therapeutic target.
