Abstract 18590: Oxidative Protein Modifications Mediate Mitochondrial Dysfunction in Metabolic Heart Disease: Correction ex vivo and in vivo
Background: Diet-induced metabolic heart disease (MHD) characterized by LV hypertrophy (LVH), diastolic dysfunction and oxidative post-translational modifications (OPTM) of cardiac mitochondrial proteins suggests that mitochondrial reactive oxygen species (ROS) contribute to MHD.
Hypothesis: We tested the hypotheses that in MHD mitochondrial dysfunction can be i) reversed by a reducing agent ex vivo, and ii) prevented by overexpression of mitochondria-targeted catalase (mCAT) in vivo.
Methods and Results: mCAT or wildtype (WT) mice were fed a high-fat, high-sucrose (HFHS) or control diet (CD) for 4 months. Cardiac mitochondria from WT HFHS-fed mice (vs. CD) had a 3-fold greater rate of H2O2 production (p=0.001), a 30% decrease in complex II substrate-driven oxygen consumption (p=0.006), a 22% decrease in complex I and II substrate-driven ATP synthesis (p=0.01) and a 63% decrease in complex II activity (p=0.002). In WT HFHS-fed mice, complex II but not complex I substrate-driven ATP synthesis and activity were completely restored ex vivo by dithiothreitol (5mM), a thiol reducing agent specific for reversible cysteine (Cys) OPTM. In WT mice, HFHS-feeding caused LVH (+20% in total wall thickness; p<0.01) and diastolic dysfunction (-30% in Em; p<0.01). In mCAT mice all HFHS diet-induced mitochondrial functional abnormalities were prevented, as were diastolic dysfunction and LVH. Using a novel mass spectrometry-based Cys labeling approach, we found that HFHS feeding is associated with reversible oxidation of Cys89 and 231 in complex II subunit A, and Cys100, 103 and 115 in complex II subunit B. In vitro, mutation of complex II subunit B redox-sensitive Cys100 or 103 to redox-insensitive serines ameliorated ROS-induced complex II dysfunction.
Conclusion: Diet-induced MHD leads to mitochondrial ROS and dysfunction involving OPTM of complex I and II. HFHS feeding causes reversible OPTM of Cys100 and 103 in complex II subunit B that are involved in ROS-mediated dysfunction. In mCAT mice, HFHS-induced dysfunction of both complex I and II, LVH and diastolic dysfunction were prevented. Mitochondrial ROS causes reversible and irreversible OPTM of mitochondrial proteins that play a key role in the pathogenesis of MHD.
- Oxidative stress
- Mitochondrial energetics, heart failure, arrhythmias
- Diastolic function
Author Disclosures: A.L. Sverdlov: None. A. Elezaby: None. F. Qin: None. J.B. Behring: None. M.M. Bachschmid: None. I. Luptak: None. T.D. Calamaras: None. D.A. Siwik: None. E.J. Miller: None. M. Liesa: None. O.S. Shirihai: None. D.R. Pimentel: None. R.A. Cohen: None. W.S. Colucci: None.
- © 2014 by American Heart Association, Inc.