Iron-overload induced
cardiomyopathy is a major cause of morbidity and mortality in thalassemic patients. Previous studies suggest that cardiac
mitochondrial dysfunction may be involved in the pathogenesis of
cardiomyopathy in
thalassemia. We tested the hypothesis that
iron overload causes dysfunction of cardiac mitochondria isolated from thalassemic mice. Cardiac mitochondria were isolated from the heart tissue of genetically-altered, β-thalassemic mice (HT) and adult wild-type mice (WT). Ferrous
iron (Fe(2+)) at various concentrations (0-5 μg/ml) was applied to induce
iron toxicity. Pharmacological interventions, facilitated by
mitochondrial permeability transition pore (mPTP) blocker, CsA, and mitochondrial Ca(2+) uniporter (MCU) blocker,
Ru360, were used to study their respective effects on cardiac
mitochondrial dysfunction. Cardiac mitochondrial ROS production, mitochondrial membrane potential changes, and mitochondrial swelling were determined.
Iron overload caused increased ROS production, mitochondrial depolarization, and mitochondrial swelling in a dose-dependent manner in WT and HT cardiac mitochondria. CsA decreased only ROS production in WT and HT cardiac mitochondria, whereas
Ru360 completely prevented the development of cardiac
mitochondrial dysfunction by decreasing ROS, mitochondrial depolarization, and swelling in both WT and HT cardiac mitochondria.
Ru360, an MCU blocker, provides protective effects by preventing ROS production and mitochondrial depolarization as well as attenuating mitochondrial swelling caused by Fe(2+) overload. These findings indicate that the MCU could be a major portal for Fe(2+) entry into cardiac mitochondria. Therefore, blocking MCU may be an effective
therapy to prevent
iron-overload induced cardiac
mitochondrial dysfunction in patients with
thalassemia.