Abstract 15238: Cardiomyocyte Specific Pellino1 Knockout Leads to Increased Oxidative Stress, Reduced Anti-apoptotic Signaling and Cardiac Dysfunction in a Murine Myocardial Infarction Model

Abstract

Introduction: Ischemic heart disease is the leading cause of death in adults in the US. We have shown that overexpression of E3 ligase Pellino1 (Peli1) increased vessel density, triggered anti-apoptotic signaling, and preserved cardiac function in the infarcted myocardium. In the present study, we aimed to explore whether the loss of Peli1 function in cardiomyocytes has any effect on cardiac function using a genetically-modified murine myocardial infarction (MI) model. Methods: Wild type (WT) and cardiomyocyte-specific Peli1 knockout (CP1KO -/- ) mice were divided into 4 groups [wild-type-sham (WTS), CP1KO -/- sham (CP1KO -/- S), WTMI and CP1KO -/- MI] to undergo either left anterior descending artery ligation or sham surgery. Phosphorylation of Mitogen-Activated Protein Kinase-Activated Protein Kinase-2 (p-MK2) and expression of VEGF, Bcl2, and cIAP2 were quantified by Western blot analysis. Cardiac function by two-dimensional echocardiography was performed at 30 days post-op to assess ejection fraction (EF), fractional shortening (FS), left ventricular internal diameter in both systole and diastole (LVIDs and LVIDd). Results: We observed no significant change in cardiac functions between WTS and CP1KO-/-S group. However, in MI groups, CP1KO -/- mice showed significant loss of systolic functions, represented by both EF (26.60%±2.340 vs. 33.46%±1.84; p<0.029, n=13) and FS (12.43%± 1.19 vs. 15.93%±0.98; n=13, p<0.03) when compared to WTMI group. Western blot analysis of heart tissue 24-hour post-MI showed a significant reduction in the expression of p-MK2 (p=0.0045) in CP1KO -/- group compared to WT mice. Similarly, expression of VEGF (p=0.0227), BCl-2 (p=0.0073) and cIAP2 (p=0.0483) was also found to be significantly downregulated in CP1KO -/- group compared to WTMI group at 4-day post-MI. We also analyzed oxidative stress marker, 3-NT, which was significantly upregulated (p=0.0001) in CP1KO mice compared to WTMI. Conclusion: Loss of Peli1 in cardiomyocyte results in the impairment of cardiac function along with increased oxidative stress, reduced angiogenic and survival protein expression, which suggests Peli1 plays an important role in the cardiomyocyte signaling during myocardial infarction.