Downregulation of Peroxisome Proliferator–Activated Receptor-α Gene Expression in a Mouse Model of Ischemic Cardiomyopathy Is Dependent on Reactive Oxygen Species and Prevents Lipotoxicity
- 19 July 2005
- journal article
- research article
- Published by Ovid Technologies (Wolters Kluwer Health) in Circulation
- Vol. 112 (3), 407-415
- https://doi.org/10.1161/circulationaha.105.536318
Abstract
Background— The peroxisome proliferators–activated receptor-α (PPARα), a transcription factor that modulates fatty acid metabolism, regulates substrate preference in the heart. Although in acute ischemia there is a switch in substrate preference from fatty acids to glucose, metabolic gene expression in repetitive ischemia is not well described. In a mouse model of ischemic cardiomyopathy induced by repetitive ischemia/reperfusion (I/R), we postulated that downregulation of PPARα is regulated by reactive oxygen species and is necessary for maintaining contractile function in the heart. Methods and Results— Repetitive closed-chest I/R (15 minutes) was performed daily in C57/BL6 mice, mice overexpressing extracellular superoxide dismutase, and mice treated with the PPARα agonist-WY-14,643. Echocardiography, histology, and candidate gene expression were measured at 3, 5, 7, and 28 days of repetitive I/R and 15 and 30 days after discontinuation of I/R. Repetitive I/R was associated with a downregulation of PPARα-regulated genes and both myosin heavy chain isoform transcript levels, which was reversible on discontinuation of I/R. Overexpression of EC-SOD prevented the downregulation of PPARα-regulated genes and myosin iso-genes by repetitive I/R. Furthermore, reactivation of PPARα in mice exposed to repetitive I/R worsened contractile function, induced microinfarctions, and increased intramyocardial triglyceride deposition, features suggestive of cardiac lipotoxicity. Conclusions— Metabolic and myosin isoform gene expression in repetitive I/R is mediated by reactive oxygen species. Furthermore, we suggest that downregulation of PPARα in repetitive I/R is an adaptive mechanism that is able to prevent lipotoxicity in the ischemic myocardium.Keywords
This publication has 34 references indexed in Scilit:
- Intramyocardial lipid accumulation in the failing human heart resembles the lipotoxic rat heartThe FASEB Journal, 2004
- Dynamic changes of gene expression in hypoxia-induced right ventricular hypertrophyAmerican Journal of Physiology-Heart and Circulatory Physiology, 2004
- Activation of Peroxisome Proliferator–Activated Receptor-α Protects the Heart From Ischemia/Reperfusion InjuryCell Metabolism, 2003
- The role of uncoupling proteins in the regulation of metabolismActa Physiologica Scandinavica, 2003
- Persistent Stunning Induces Myocardial Hibernation and ProtectionCirculation Research, 2003
- The Physiology of Cellular LiporegulationAnnual Review of Physiology, 2003
- Mechanisms of LipoapoptosisTrends in Cardiovascular Medicine, 2002
- Hypoxia in Vivo Decreases Peroxisome Proliferator-Activated Receptor α-Regulated Gene Expression in Rat HeartBiochemical and Biophysical Research Communications, 2001
- Hibernating myocardiumHeart, 2000
- The ATPase activities of rat cardiac myosin isoenzymesFEBS Letters, 1980