Abstract 16199: Mutation of the SERCA-Reactive Cysteine-674 to Serine Attenuates Myocyte Apoptosis and Heart Failure in Mice With Chronic Pressure Overload
Introduction: Irreversible oxidation of sarcoplasmic reticulum (SR) calcium ATPase (SERCA2) at cysteine 674 (C674) prevents redox regulation of enzyme activity. In mice with pressure overload due to aortic constriction, we previously showed that SERCA2 C674 is oxidized and that its oxidation as well as myocyte apoptosis and left ventricular (LV) failure are prevented by transgenic expression of catalase. Therefore, SERCA2 oxidation may contribute to impaired SR filling leading to mitochondrial dysfunction and apoptosis.
Hypothesis: We tested whether oxidation of SERCA2 C674 is necessary for pressure overload-induced LV apoptosis and failure.
Methods and Results: Heterozygote SERCA2 knock-in mice (SKI) in which 50% C674 is mutated to serine and wild-type mice (WT) 10 weeks of age were subjected to ascending aortic constriction (AAC) or sham operation (n=7-12 per group). Echocardiography and immunohistochemistry were performed 12 weeks after AAC. In WT, AAC caused LV failure with increased LV end diastolic dimension (EDD: 3.7±0.3 vs. 2.9±0.1 mm in sham; P<0.01) and decreased LV fractional shortening (FS: 41±4 vs. 61±0.3 % in sham; P<0.001). In SKI, AAC caused less LV dilation (EDD = 3.1±0.1mm; P<0.05 vs. WT/AAC) and LV contractile function was preserved (FS = 58±1%; P<0.001 vs. WT/AAC). In WT, AAC increased myocardial oxidative stress as reflected by 4-hydroxy-2-nonenal (HNE) staining, and caused oxidation of SERCA2 at C674, assessed with a sequence-specific antibody for SERCA2-SO3H. In SKI mice, myocardial oxidative stress was decreased partially and oxidation of SERCA2 C674 was less. AAC increased apoptotic myocytes measured by TUNEL staining in WT mice (21±1 vs. 3±1 per 10,000 myocytes in sham; P<0.05), and the increase was inhibited in SKI mice (4±2 per 10,000 myocytes; P<0.05 vs. WT/AAC). AAC increased active caspase-3 expression in WT but not SKI.
Conclusion: The SERCA2-C674S mutant decreases pressure overload-induced oxidation of SERCA2 C674, myocardial oxidative stress, myocyte apoptosis, LV remodeling, and progression to failure. Oxidation of SERCA2 C674 plays a critical role in mediating pressure overload-induced myocyte apoptosis and myocardial failure.
Author Disclosures: F. Qin: None. R.J. Morgan: None. D.A. Siwik: None. X. Tong: None. R.A. Cohen: None. W.S. Colucci: None.
- © 2014 by American Heart Association, Inc.