Abstract 14182: Identification of a Candidate Alternative Fuel Source in the Failing Heart Using Quantitative Mitochondrial Proteomics and Metabolomics
Significant evidence suggests that derangements in mitochondrial fuel and energy metabolism contribute to the pathogenesis of heart failure (HF). To identify changes in mitochondrial proteins relevant to the metabolic re-programming events that occur during pathologic cardiac remodeling, unbiased quantitative mitochondrial proteomics using in vivo stable isotope labeling by amino acids (SILAC) was employed. Quantitative changes in the mitochondrial proteome were determined in samples collected from hearts of mice with compensated (transverse aortic constriction; TAC) and decompensated (transverse aortic constriction + myocardial infarction; HF) cardiac hypertrophic remodeling, and corresponding sham-operated controls 4 weeks post-surgery. Following in-gel digestion, samples were subjected to mass spectrometric analysis (LTQ Orbitrap). Based on a false discovery rate of 1%, 1689 proteins were identified. Using the DAVID server platform, 756 proteins were identified as “mitochondrial” based on GOCC annotation. By applying cutoffs of <0.8 or >1.5, 81 proteins were determined to be regulated either in TAC (compensated), HF (decompensated) or both compared to controls. Notably, 3-hydroxybutyrate dehydrogenase 1 (BDH-1), a key enzyme involved in ketone body metabolism, was upregulated in both TAC and HF. qRT-PCR studies using independent samples demonstrated an increase in BDH-1 gene expression in TAC (1.41 fold) and HF (2.45 fold). Western blot validation studies confirmed a 2.93-fold increase in a separate heart failure mitochondrial preparation. Further analysis of the proteomic dataset demonstrated increased levels of other enzymes regulated in the cardiac ketone metabolism pathway including succinyl-CoA:3-ketoacid-coenzyme A transferase 1 (SCOT), which was increased 1.3 fold in TAC and HF. Metabolomic profiling on subsequent samples demonstrated an increase in succinate (1.2 fold; p≤0.05) in HF likely reflecting the utilization of succinyl-CoA as a source of CoA for acetoacetate utilization by SCOT. Moreover, 3-hydroxybutanoyl-CoA, a by-product of the ketone pathway, was increased 2.1 fold in HF. These results identify ketone bodies as a potential alternative fuel source for the failing “energy-starved” heart.
- © 2011 by American Heart Association, Inc.