Mice lacking mitochondrial ferritin are more sensitive to doxorubicin-mediated cardiotoxicity

Mitochondrial ferritin is a functional ferritin that localizes in themitochondria.Itisexpressedinthetestis, heart,brain,and cells with active respiratory activity. Its overexpression in culturedcellsprotectedagainstoxidativedamageandreduced cytosolic iron availability. However, no overt phenotype was describedinmicewithinactivationoftheFtMtgene.Here,we usedthe doxorubicin model ofcardiac injuryina novel strain of FtMt-null mice to investigate the antioxidant role of FtMt. These mice did not show any evident phenotype, but after acute treatment to doxorubicin, they showed enhanced mortalityandaltered heartmorphologywithfibrildisorganization and severe mitochondrial damage. Signs of mitochondrial damage were present also in mock-treated FtMt−/− mice. The hearts of saline- and doxorubicin-treated FtMt−/− mice had higher thiobarbituric acid reactive substance levels, heme oxygenase 1 expression, and protein oxidation, but did not differ from FtMt+/+ in the cardiac damage marker B-type natriureticpeptide(BNP),ATP levels, and apoptosis.However,the autophagy marker LC3 was activated. The results show that the absence of FtMt, which is highly expressed in the heart, increases the sensitivity of heart mitochondria to the toxicity of doxorubicin. This study represents the first in vivo evidence of the antioxidant role of FtMt.