Abstract 20301: Reversible Oxidation Of Metabolic Protein Triosephosphate Isomerase in the Type 2 Diabetic Heart
Introduction: Type 2 diabetes (T2D) impairs the ability of the heart to switch between fatty acid metabolism and glycolysis. This metabolic inflexibility is particularly damaging during I/R, as the oxygen independent nature of glycolytic metabolism enables energy production during oxygen deprivation. Possibly contributing to this altered metabolism is the increased oxidative stress associated with T2D, leading to reversible oxidation of the highly reactive amino acid cysteine (Cys). These oxidative modifications are associated with dysregulation of signalling, altered protein structure and increased protein degradation. High-throughput enrichment of peptides containing these modifications may enable the identification of potential molecular mechanisms underlying the metabolic inflexibility of the T2D heart.
Methods: Sprague Dawley rats were fed either CHOW (CH) (12% fat) or high fat (HF) (42% fat) diet for 4 weeks prior to a low dose of the pancreatic β-cell toxin, Streptozocin (STZ; 35mg/kg) to induce T2D in half the population for a further 4 weeks. Upon completion of the 8-week protocol, hearts were excised and exposed to 60 minutes continuous perfusion. Myocardial peptides were isobaric labelled and thiol-disulfide exchange enrichment performed, followed by tandem mass spectrometry analysis.
Results and Conclusion: High-throughput enrichment identified 11,824 unique reversibly oxidised Cys containing peptides, originating from 3,652 proteins. Significantly regulated peptides were observed to be changing more than 2-fold. Cluster analysis and functional pathways mapping isolated metabolic proteins showing the highest level of regulation within the HF + STZ group. In particular the protein triosephosphate isomerase (Tpi1) was seen to undergo an increase in modification at Cys159 (fold-change; 2.30). Reversible oxidation of this protein has recently been associated with impaired glucose cycling and may provide a mechanism behind the reduced metabolic flexibility in the T2D heart that contributes to the enhanced damage that occurs during I/R.
Author Disclosures: L.E. Smith: None. B. Hambly: None. S. Cordwell: None. M. White: None.
- © 2016 by American Heart Association, Inc.