Abstract P425: Sirtuin 3 Attenuates Doxorubicin Induced Cardiac Dysfunction By Regulating The Mitochondrial Acetylome And Alterations Of The Cardiac Lipidome

Abstract

Doxorubicin (DOX) is a chemotherapeutic with dose-dependent cardiotoxic effects that limits its use in patients. Previously we showed that DOX decreases expression of the mitochondrial lysine deacetylase SIRT3 in the mouse heart. We hypothesize that DOX impairs cardiac function and energy production through reduced SIRT3 and altered mitochondrial acetylation. We further hypothesize that increased SIRT3 expression could attenuate DOX-induced cardiac dysfunction via alterations of protein acetylation to enzymes involved in lipid remodeling and metabolic processes. Mice expressing cardiac restricted full length M1-SIRT3 (mitochondrial localized), and short M3-SIRT3 (lacking localization signal) received saline or DOX injections of 8 mg/kg body weight for 4 weeks and compared to non-transgenic (Non-Tg) littermates. Transthoracic echocardiography was performed on all mice (n=10). Total cardiac lipids were isolated from DOX treated cardiac tissue by chloroform:methanol extraction and global lipid analysis was performed by QTRAP LC-MS/MS (n=6). Cardiac mitochondria were and an anti-acetylated lysine antibody was used to enrich for tryptic digested peptides containing Acetyl-K and analyzed by QTRAP LC-MS/MS (n=6). In non-Tg mice, DOX caused cardiac dysfunction and expression of M1-SIRT3 and M3-SIRT3 transgenes in the heart preserved left ventricular posterior wall thickness (P<0.05) and ejection fraction (P<0.05) in DOX treated mice. Triglycerides and phospholipids (PE, PI, PC) were decreased in DOX treated mouse hearts while phosphatidylserine (PS), sphingomyelin and ganglioside (GM3) lipid species were increased (p<0.05). A negative correlation between decreased cardiac output and increased GM3 24:1 (R=-0.62, P<0.05), PS 38:4 levels (R=-0.81, P<0.005) and SM 35:1 (R=-0.65, P<0.05) was identified. 36 acetylated peptides involved in metabolic processes, oxidative stress resistance and lipid remodeling (eg. IDH2, SOD2, HADHA, P<0.05) were significantly altered in DOX-treated mice. Increased SIRT3 expression in the heart rescues DOX-induced cardiac dysfunction. DOX-induced cardiac dysfunction involved alterations in cardiac lipids and acetylated proteins that could be rescued by increased SIRT3 expression in the heart.