Proteomic analyses of transgenic LQT1 and LQT2 rabbit hearts elucidate an increase in expression and activity of energy producing enzymes

• Published in: Journal of proteomics 2012-09, Vol.75 (17), p.5254-5265
• Main Authors: Jindal, Hitesh K., Merchant, Elisabeth, Balschi, James A., Zhangand, Yajie, Koren, Gideon
• Format: Article
• Language: English
• Subjects: 2-D DIGE; acyl-CoA dehydrogenase; adenosine triphosphate; aldehyde dehydrogenase; analysis; Animals; Animals, Genetically Modified; beta oxidation; biochemical pathways; Biological and medical sciences; Cardiac dysrhythmias; Cardiology. Vascular system; chemistry; creatine kinase; Diverse techniques; electrophoresis; Energetics; energy; Energy Metabolism; Enzyme Activation; Enzymes; Ether-A-Go-Go Potassium Channels; fatty acids; fluorescence; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Enzymologic; genetically modified organisms; genetics; glycogen; Heart; KCNQ1 Potassium Channel; lactate dehydrogenase; Long QT Syndrome; Male; Mass spectrometry; Medical sciences; Metabolic remodeling; metabolism; methods; Molecular and cellular biology; Myocardium; pathology; phosphorylase; physiology; protein disulfide-isomerase; protein synthesis; Proteome; Proteomics; pyruvate dehydrogenase (lipoamide); rabbits; Romano-Ward Syndrome; succinate dehydrogenase; succinate dehydrogenase (quinone); Western blotting
• ISSN: 1874-3919; 1876-7737
• DOI: 10.1016/j.jprot.2012.06.034

Various biochemical and genomic mechanisms are considered to be a hallmark of metabolic remodeling in the stressed heart, including the hypertrophied and failing heart. In this study, we used quantitative proteomic 2-D Fluorescence Difference In-Gel Electrophoresis (2-D DIGE) in conjunction with mass spectrometry to demonstrate differential protein expression in the hearts of transgenic rabbit models of Long QT Syndrome 1 (LQT1) and Long QT Syndrome 2 (LQT2) as compared to littermate controls (LMC). The results of our proteomic analysis revealed upregulation of key metabolic enzymes involved in all pathways associated with ATP generation, including creatine kinase in both LQT1 and LQT2 rabbit hearts. Additionally, the expression of lamin-A protein was increased in both LQT1 and LQT2 rabbit hearts as was the expression of mitochondrial aldehyde dehydrogenase and desmoplakin in LQT1 and LQT 2 rabbit hearts, respectively. Results of the proteomic analysis also demonstrated down regulation in the expression of protein disulfide-isomerase A3 precuorsor and dynamin-like 120kDa protein (mitochondrial) in LQT1, and of alpha-actinin 2 in LQT2 rabbit hearts. Up regulation of the expression of the enzymes associated with ATP generation was substantiated by the results of selective enzyme assays in LQT1 and LQT2 hearts, as compared to LMC, which revealed increases in the activities of glycogen phosphorylase (+50%, +65%, respectively), lactate dehydrogenase (+25%, +25%) pyruvate dehydrogenase (+31%, +22%), and succinate dehydrogenase (+32%, +60%). The activity of cytochrome c-oxidase, a marker for the mitochondrial function was also found to be significantly elevated (+80%) in LQT1 rabbit hearts as compared with LMC. Western blot analysis in LQT1 and LQT2 hearts compared to LMC revealed an increase in the expression of very-long chain-specific acyl-CoA dehydrogenase (+35%, +33%), a rate-limiting enzymes in β-oxidation of fatty acids. Collectively, our results demonstrate similar increases in the expression and activities of key ATP-generating enzymes in LQT1 and LQT2 rabbit hearts, suggesting an increased demand, and in turn, increased energy supply across the entire metabolic pathway by virtue of the upregulation of enzymes involved in energy generation. [Display omitted] ► 2-D DIGE was used to analyze the proteomes in long QT syndrome I and II rabbit hearts ► Differentially expressed proteins were identified in long QTS rabbit hearts ► There was increased expression