IF1 Knockout Protects Against Doxorubicin-Induced Cardiac Dysfunction by Improving Cardiomyocyte Energetics

Abstract

Doxorubicin (DOX), a member of the Anthracycline antibiotics class, has been used as a potent chemotherapy agent against solid tumors. However, its use is limited by its cardiotoxicity. It is well-documented that mitochondrial dysfunction is one of the main mechanisms of DOX-induced cardiotoxicity. ATP synthase inhibitory subunit 1 (ATPIF1, or IF1) is an endogenous inhibitor of mitochondrial ATP synthase. Recent studies indicate that IF1 may suppress mitochondrial respiration via inhibiting ATP synthase. Others and our previous studies demonstrated that IF1 inactivation exerts hepatic and cardiac protective effects. We hypothesize that the absence of IF1 protects the heart from DOX-induced cardiotoxicity by improving mitochondrial energy metabolism. We first investigate the impact of IF1 KO on mitochondrial respiration using the high-resolution respirometer (OROBOROS) on freshly isolated cardiac mitochondria from IF1 KO and WT mice. IF1 KO mitochondria did show substantially increased state 2, state 3, and state 4 respiration rates compared with those of WT. We then investigated if WT and IF1 KO mice respond differently to DOX treatment. WT and IF1 KO mice at the ages of 12-16 weeks either received DOX 3mg/kg/every other day or vehicle intraperitoneally for two weeks. In vivo, cardiac function was evaluated using the VEVO F2 Echocardiographic system (Visual Sonic) 4 and 6 weeks after initiation of DOX and vehicle administration. Compared with the vehicle-treated WT mice, left ventricular ejection fraction (LVEF) was substantially decreased in DOX-treated WT mice compared with vehicle-treated WT mice. In contrast, LVEF in DOX-IF1 KO mice was substantially less reduced compared with vehicle-treated IF1 KO mice. We next investigated if improving cellular energetics is the critical mechanism underlying the protective effects of IF1 KO. Mouse neonatal cardiomyocyte (NMCM) isolated from WT and IF1 KO mice were cultured and treated with 0.5 and 1mM Dox for 24 hours. Cellular energetics were measured with the Mito stress assay using the Seahorse Bioanalyzer (96Xpro, Agilent). Basal, maximal, and ATP production-linked oxygen consumption rates were markedly decreased in DOX-treated-NMCM but not in DOX-treated IF1 KO NMCM compared with Vehicle-treated NMCM. In summary, the above in vivo and in vitro investigations support that IF1 inactivation is protective against DOX cardiac toxicity, at least partly, via improving cellular energetics; therefore, inactivating IF1 may be a potential therapeutic target to prevent and mitigate DOX-induced cardiomyopathy in patients. This research was supported by project number 5R01HL160969 from the National Heart Lung and Blood Institute at the NIH. This is the full abstract presented at the American Physiology Summit 2024 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.