Potential role of Ferrostatin-1 as a mitochondrial-targeting agent for treatment of mitochondrial cardiomyopathy
Authors: Cantrell Aubrey , Besanson Jessie , Zeng Heng , Williams Quinesha , Chen Jian-Xiong 
Published: May 2023

AIMS: Ferroptosis is becoming increasingly recognized as a contributor to disease states, including heart failure (HF) and other conditions such as Friedreich’s ataxia (FRDA). FRDA is primarily classified as a neurodegenerative disease and is caused by an incomplete loss of the mitochondrial protein frataxin, which is involved in iron homeostasis. This deficiency often leads to a fatal mitochondrial cardiomyopathy, which is the leading cause of death in FRDA patients. Our recent study reveals that cardiomyocyte-specific knockout of Sirtuin 3 (SIRT3cKO) in mice results in cardiac dysfunction followed by activation of the ferroptotic cell death pathway. We hypothesized that SIRT3cKO mice exhibit similarities to the mitochondrial cardiomyopathy seen in FRDA, and that treating these mice with the pharmacologic ferroptosis inhibitor Ferrostatin-1 (Fer-1) would improve cardiac function in SIRT3cKO mice and reveal a potential therapeutic target for the treatment of mitochondrial cardiomyopathies such as FRDA. METHODS AND RESULTS: SIRT3cKO and SIRT3loxp (WT) mice were injected with Fer-1 (1mg/kg/day) for 14 days i.p. Echocardiographic measurements were performed at days 0, 7, and 14. Left ventricles were harvested and fractionated into mitochondrial and cytosolic compartments for Western blot analysis.Echocardiography revealed that SIRT3cKO mice have severely impaired systolic function shown by reduced EF% and FS% compared to that of SIRT3loxp mice. These alterations are significantly improved, although not entirely normalized post-treatment of Fer-1.Gene expression analysis demonstrated that SIRT3cKO hearts have decreased mitochondrial GPX4 and increased 4-HNE, suggesting that ferroptosis is occurring in the mitochondria. SIRT3cKO mice also exhibit decreased expression of frataxin and aconitase in the mitochondria, suggesting impairment of iron homeostasis and similarities between this heart failure phenotype and the mitochondrial cardiomyopathy associated with FRDA. After Fer-1 treatment, mitochondrial GPX4 was upregulated in SIRT3cKO mice. Intriguingly, the levels of frataxin were not significantly altered, suggesting that ferroptosis may occur downstream of frataxin deficiency. Additionally, aconitase was upregulated in SIRT3cKO mitochondria following Fer-1 treatment, suggesting improved iron homeostasis. Notably, these changes were not observed in the cytosol of SIRT3cKO mice following treatment. CONCLUSIONS: SIRT3cKO mice exhibit characteristics of the mitochondrial cardiomyopathy of FRDA. Fer-1 treatment improves cardiac function in SIRT3cKO mice by reducing mitochondrial ferroptosis and improving iron homeostasis. These changes were specific to the mitochondria, suggesting that Fer-1 may be a mitochondria-targeting agent. Taken together, our study shows that ferroptosis may occur downstream of frataxin deficiency, and the ferroptosis inhibitor Fer-1 may be a novel therapeutic agent to be used for mitochondrial cardiomyopathies such as FRDA. This work was supported by National Institute of General Medical Sciences and National Heart, Lung, and Blood Institute (R01HL151536, JX Chen), the National Heart, Lung, and Blood Institute (R56HL164321, H. Zeng). This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.