Mitochondrial Protein Hyperacetylation in Rodents with Doxorubicin‐Induced Cardiac Dysfunction

Abstract

ObjectiveDoxorubicin (DOX) is an effective chemotherapeutic but has dose‐dependent cardiotoxic effects that limits its use in pediatric patients. Previous studies in our lab showed that DOX decreases expression of the mitochondrial lysine deacetylase SIRT3 and mitochondrial phospholipid cardiolipin (CL) in the mouse heart. We hypothesize that DOX impairs cardiac function as a consequence of reduced SIRT3 expression resulting in increased acetylation of mitochondrial proteins involved in cardiac energy and oxidative stress homeostasis.MethodsC57BL6 mice were given DOX (8.0mg/kg body weight) or saline control injections for 4 weeks. Transthoracic echocardiography was performed on all mice (n=10 per group) and parameters of cardiac structure, systolic and diastolic function were measured. Cardiac mitochondria were isolated from saline and DOX mice and an anti‐acetylated lysine antibody was used to enrich for tryptic digested peptides containing acetylated lysines followed by mass spectroscopy analysis (n=6).ResultsDOX treated mice exhibit decreased left ventricular posterior wall thickness (P<0.05), increased intraventricular relaxation time and reduced ejection fraction, compared to controls (P<0.05). Quantitative PCR of cardiolipin biosynthesis genes revealed Ptpmt1 and Crls1 gene expression was reduced by half with DOX compared to controls (p<0.01). In DOX treated mice, we observed an enrichment of cardiac mitochondrial acetylated peptides of proteins involved in metabolic, CL remodelling processes and oxidative stress resistance (eg. ATP5F1A, TFEα, SOD2, P<0.05, >2‐fold increase). MitoSOX staining of human induced pluripotent stem cell derived cardiomyocytes revealed an increase (2.5‐fold, p<0.001) in reactive oxygen species production with DOX treatment which was attenuated with adenoviral SIRT3 overexpression.ConclusionAlterations to the mitochondrial acetylome may be responsible for DOX‐induced cardiac dysfunction in mice. SIRT3 overexpression attenuates production of reactive oxygen species in human derived cardiomyocytes and SIRT3 may prevent cardiotoxic effects of DOX.