Abstract 14664: SIRT3 Protects Cardiomyocytes From Doxorubicin-induced Mitochondrial Damage and Cell-death by Activating Opa1
Introduction: The anti-cancer drug therapy with doxorubicin (Dox) is known to produce cardiomyopathy associated with fragmentation of mitochondria and excess production of reactive oxygen species (ROS). Sirtuin3 (SIRT3), a mitochondrial deacetylase regulates many mitochondrial functions including energy production, ROS synthesis and cell-death. A role of SIRT3 in regulating the aging process and aging-associated diseases like heart failure, cancer and diabetes has been also documented. This study was undertaken to investigate whether SIRT3 can protect cardiomyocytes from Dox-induced mitochondrial damage and cell-death.
Methods and Results: Neonatal rat cardiomyocytes were over expressed with a vector synthesizing SIRT3 or a mock vector. Cells were treated with Dox (100nM) for 72 hours and cell-death was analyzed by measuring TUNEL-positive nuclei, ROS synthesis and expression of apoptotic markers by the western blotting. There was marked reduction of TUNEL-positive nuclei, ROS levels and expression of apoptotic markers such as Bax, Bim and FasL in SIRT3 over expressing cells, compared to control cells received the mock vector. Confocal imaging of myocytes revealed that Dox-treatment caused swelling and fragmentation of mitochondria in control cells, but not in cells over expressed with SIRT3. To understand the mechanism involved in SIRT3-mediated protection of mitochondria we analyzed acetylation of proteins involved in regulating mitochondrial fusion-fission dynamics. We found that OPA1 (optic atrophy-1), an essential inner membrane fusion protein, was hyper-acetylated in Dox-treated cells, leading to its reduced GTPase activity. SIRT3 was capable of deacetylating and augmenting GTPase activity of OPA1 both in vitro and in vivo assay conditions. Furthermore, by studying OPA1 null cells we found that it is necessary for SIRT3-mediated protection of cardiomyocytes from mitochondrial damage and cell-death.
Conclusions: These results indicated that SIRT3-dependent activation of OPA1 contributes to preservation of mitochondrial population and protection of cardiomyocytes from Dox-mediated cell-death. We believe that SIRT3 could be utilized as a therapeutic target for treatment of Dox-induced cardiomyopathy of the heart.
Author Disclosures: S. Samant: None. V. Pillai: None. D. Wolfgeher: None. M. Gupta: None.
- © 2014 by American Heart Association, Inc.