Mitochondrial protein hyperacetylation in the failing heart
Julie L. Horton, Ola J. Martin, Ling Lai, Nicholas M. Riley, Alicia L. Richards, Rick B. Vega, Teresa C. Leone, David J. Pagliarini, Deborah M. Muoio, Kenneth C. Bedi Jr., Kenneth B. Margulies, Joshua J. Coon, Daniel P. Kelly
Julie L. Horton, Ola J. Martin, Ling Lai, Nicholas M. Riley, Alicia L. Richards, Rick B. Vega, Teresa C. Leone, David J. Pagliarini, Deborah M. Muoio, Kenneth C. Bedi Jr., Kenneth B. Margulies, Joshua J. Coon, Daniel P. Kelly
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Research Article Cardiology Metabolism

Mitochondrial protein hyperacetylation in the failing heart

Abstract

Myocardial fuel and energy metabolic derangements contribute to the pathogenesis of heart failure. Recent evidence implicates posttranslational mechanisms in the energy metabolic disturbances that contribute to the pathogenesis of heart failure. We hypothesized that accumulation of metabolite intermediates of fuel oxidation pathways drives posttranslational modifications of mitochondrial proteins during the development of heart failure. Myocardial acetylproteomics demonstrated extensive mitochondrial protein lysine hyperacetylation in the early stages of heart failure in well-defined mouse models and the in end-stage failing human heart. To determine the functional impact of increased mitochondrial protein acetylation, we focused on succinate dehydrogenase A (SDHA), a critical component of both the tricarboxylic acid (TCA) cycle and respiratory complex II. An acetyl-mimetic mutation targeting an SDHA lysine residue shown to be hyperacetylated in the failing human heart reduced catalytic function and reduced complex II–driven respiration. These results identify alterations in mitochondrial acetyl-CoA homeostasis as a potential driver of the development of energy metabolic derangements that contribute to heart failure.

Authors

Julie L. Horton, Ola J. Martin, Ling Lai, Nicholas M. Riley, Alicia L. Richards, Rick B. Vega, Teresa C. Leone, David J. Pagliarini, Deborah M. Muoio, Kenneth C. Bedi Jr., Kenneth B. Margulies, Joshua J. Coon, Daniel P. Kelly

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Figure 5

Evidence for acetylation effects on succinate dehydrogenase A function relevant to heart failure.

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Evidence for acetylation effects on succinate dehydrogenase A function r...
(A) Mitochondrial complex II respiration rates determined on cardiac muscle strips isolated from heart failure (HF) and sham-operated control mice using succinate (5 mM) as a substrate in the presence of rotenone (10 μM) to inhibit complex I flux. Basal, state 3 (ADP-stimulated), and post-oligomycin VO2 rates are shown normalized to mg dry tissue weight (mg dw). RC, respiratory control ratio (state 3/state 4). Bars represent mean respiration rates ± SEM (n = 5–11). *P < 0.05 compared to sham based on Student’s t test. (B) Succinate dehydrogenase A (SDHA) activity was measured in mitochondria isolated from HEK293 cells expressing WT SDHA (WT) or the acetyl-mimetic mutant (K179Q). Km was derived from measurements of initial velocity generated from a range of substrate concentrations using nonlinear regression. Bars represent mean values ± SEM (3 separate experiments each with n = 3/condition). *P < 0.05 compared to WT based on Student’s t test. (C) Oxygen consumption rates (OCRs) were measured in permeabilized NIH-3T3 cells transfected with either a vector encoding WT SDHA (pCS6-SDHA) or K179Q (pCS6-K179Q). The OCR was normalized to the total amount of SDHA in each sample, as quantified by Western blot. The graph shown is representative of 3 separate experiments, each with n = 10. Data points represent mean values ± SEM. *P < 0.05 compared to SDHA-K179Q based on Student’s t test. (D) Area under the curve (AUC) was calculated from the combination of all 3 individual experiments for basal and succinate-driven respiration (n = 30). Bars represent mean values ± SEM. *P < 0.05 compared to WT based on Student’s t test.