Background
Doxorubicin (DOX) is a chemotherapeutic used in the treatment cancer, however it has dose-dependent cardiotoxic side effects such as the development of dilated cardiomyopathy. Previously, we showed that DOX treatment decreases the expression of mitochondrial lysine deacetylase, sirtuin 3 (SIRT3) and alters mitochondrial protein acetylation of enzymes involved in cardiac energy production and oxidative stress in wild-type mice. Cardiac expression of full length mitochondrial localized M1-SIRT3 prevented cardiac remodelling and dysfunction characteristic of dilated cardiomyopathy in female mice. Here, we hypothesize that M1-SIRT3 expression could attenuate DOX-induced cardiac dysfunction by regulating the acetylation of enzymes involved in lipid remodelling and metabolic processes.
Methods and Results
DOX (8mg/kg body weight for 4 weeks) was administered to mice with cardiac restricted expression of full length M1-SIRT3 (mitochondrial localized) and short form M3-SIRT3 (lacking the mitochondrial localization sequence) or non-transgenic (Non-Tg) littermates (control groups received saline). Transthoracic echocardiography was performed in male mice from all groups (n=8-13). Cardiac mitochondria were isolated, and a pan acetylated lysine antibody was used to enrich for peptides containing acetylation modifications in M3-SIRT3 and M1-SIRT3 transgenic animals by QTRP LC-MS/MS (n=6). Global lipidomic analysis of cardiac tissue was performed by QTRAP LC-MS/MS (n=6) in all groups. Expression of genes involved in metabolic processes was performed by quantitative PCR (n=6). Radio-labeled 18F-Fluorodeoxyglucose (18F-FDG) was used to examine glucose uptake by PET/MRI imaging (n=6). DOX treatment in Non-Tg male mice caused cardiac dysfunction, whereas expression of M3-SIRT3 and M1-SIRT3 attenuated cardiac remodeling and reduced ejection fraction (p < 0.05). Analysis of acetylated peptides revealed that DOX increased the acetylation of several proteins involved in cardiac energy production (e.g. ACO2 and ATP5PB) and lipid metabolism (e.g., HADHA) while M1-SIRT3 expression mitigated these effects. Lipidomic analysis of cardiac tissue identified an increase in proapoptotic lipid markers including gangliosides and phosphatidylserine species and a large decrease in triglyceride lipid species in DOX treated mice. Quantitative PCR identified increases in Cpt1a (p < 0.05) and Lipe (p=0.0518) in DOX treated Non-Tg mice, but not in M3-SIRT3 and M1-SIRT3 mice. DOX decreased the expression of Fapb3 and Hadha (p < 0.05) in all groups. 18F-FDG PET showed increased cardiac glucose uptake in Non-Tg, and M3-SIRT3 DOX treated mice (p < 0.05) but remined unchanged in M1-SIRT3 mice.
Conclusion
Our data show that increased M1-SIRT3 expression in the heart prevents DOX induced dilated cardiomyopathy. M1-SIRT3 expression altered mitochondrial protein acetylation while DOX decreased cardiac triglycerides and increased glucose uptake indicative of metabolic dysfunction.
Article info
Publication history
P022
Footnotes
Heart and Stroke Foundation of Canada
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© 2022 Published by Elsevier Inc.