Abstract 21518: Ischemic Human Heart Failure is Associated With Decreased Phosphorylation of Pyruvate Dehydrogenase and Triosephosphate Isomerase: Proteomic Evidence Supporting Carbohydrate Utilization Preference in the End-Stage Failing Ischemic Heart
Background: Given the inconsistent studies of metabolic enzyme abundance & their phosphorylation state (PO4) in heart failure (HF), techniques to simultaneously measure both protein abundance & PO4 in the same sample could be informative. The goal of this study was to compare protein abundance & PO4 between non-failing (NF), ischemic failing (ICM-F) & non-ischemic failing (NICM-F) human myocardium via open platform proteomics & phosphopeptide enrichment & identification.
Methods: Age-, sex-, & race-matched left ventricular tissue was obtained in a high quality manner & rapidly processed from unused human donor hearts without dysfunction or coronary artery disease (CAD) (NF, n=4) & Status 1A HF patients (pts) undergoing transplantation (F, n=8). F hearts were separated into 2 sub-groups; pts with CAD & history of CABG were designated ICM-F (n=4) or pts with non-ischemic HF etiologies were designated NICM-F (n=4). Samples were solubilized with TriZol & digested with trypsin. Peptides were then identified & quantified in an unbiased manner utilizing a gel- & label-free LC-MS/MS analysis. Samples of the same digestions were enriched with TiO2 to capture PO4 peptides and then subjected to LC-MS/MS analysis.
Results: 59 proteins were common among all 12 samples from both the unbiased & phosphopeptide analyses & allowed for proper statistical comparison. Regarding glycolytic (GLY) enzymes, the abundance of pyruvate dehydrogenase was unchanged between the 3 groups; however, PO4 at Ser271 was significantly downregulated ∼25-fold in ICM-F vs. both NI-F & NF. (p<0.01) Also, triosephosphate isomerase abundance was unchanged between the 3 groups; however, PO4 of Ser21 was significantly downregulated ∼2.4-fold in ICM-F vs. NI-F. (p<0.05). Regarding fatty acid oxidation (FAO), the abundance of medium-chain specific acyl-CoA dehydrogenase was significantly decreased in ICM-F vs. NI-F. (p<0.05)
Conclusion: Growing evidence supports a shift from FAO to GLY as the process providing energy in HF. Our results support a preference towards carbohydrates in ICM-F with regulation through kinases & phosphatases. Future studies will include unbiased & phosphopeptide analyses of NF hearts with CAD to understand the role of CAD alone on energy substrate preference.
- © 2010 by American Heart Association, Inc.