Abstract 16684: Activation of Sirtuin 3 Protects the Heart From Ischemia-Reperfusion Injury by Increased Cellular Antioxidant Defenses
Introduction: We have reported that a novel annexin-a1 biomimetic peptide (Ac-QAW) attenuates myocardial ischemia-reperfusion (IR) injury by activation of sirtuin 3 (SIRT3), a major mitochondrial protein deacetylase. However, the underlying mechanisms remain unknown.
Hypothesis: We tested the hypothesis that SIRT3 provides protection via attenuation of oxidative stress by upregulating/deacetylating manganese superoxide dismutase (MnSOD).
Methods: In-vitro simulated IR: Adult rat ventricular cardiomyocytes (ARVCs, n=3) and SIRT3-deficient ARVCs (by siRNA) were exposed to 10 μM SIRT3 activator (Ac-QAW) for 1 hour, and then subjected to oxygen-glucose deprivation (OGD) for 2 hours. In-vivo IR: Male rats (n=5) were subjected to 2 hours of cardiopulmonary bypass (CPB) with 1 hour of deep hypothermic circulatory arrest (DHCA) at 18°C, and randomized to receive vehicle or Ac-QAW (2 mg/kg, iv) 1 hour before CPB and 1 hour after reperfusion. Efficacy endpoints were assessed at 24 hours post-reoxygenation (ARVC) and post-reperfusion (rat), including apoptosis (TUNEL) and necrosis (Troponin I). SIRT3 and MnSOD activation were measured by immunoprecipitation (IP), lysine deacteylation, and western blot. Reactive oxygen species (ROS) were determined by ELISA.
Results: Pharmacologic activation of SIRT3 (by Ac-QAW) significantly attenuated myocardial necrosis and apoptosis (p<0.05) following surgical IR, while genetic down-regulation of SIRT3 (by siRNA) in cultured cardiomyocytes resulted in more cell death following simulated IR. The observed cardio and cytoprotective effects were associated with increased MnSOD activity by SIRT3-mediated lysine deacetylation (Fig. A and B) and decreased ROS following IR stress (Fig. C).
Conclusions: Ac-QAW-dependent cardioprotective effects are in part driven by pro-survival mechanisms involving increased MnSOD-mediated antioxidant defenses by SIRT3-regulated post-translational lysine deacetylation.
Author Disclosures: Z. Zhang: None. Q. Ma: None. M.V. Podgoreanu: None.
This research has received full or partial funding support from the American Heart Association.
- © 2014 by American Heart Association, Inc.