Abstract 491: Small Gtpase Rhoe Regulates Inflammatory Response in Myocardial Infarction

Abstract

Background: Myocardial infarction (MI) is a severe clinical condition caused by coronary artery thrombotic occlusion. An acute inflammatory response to MI is essential for cardiac healing, while excessive and prolonged inflammation causes cytotoxic damages and provokes adverse cardiac remodeling. In the present study, we demonstrate a novel inflammatory mediator, RhoE, and its cardioprotective role in MI. Methods: We use three genetic mouse lines in this study: global RhoE knockout, cardiac-specific RhoE haploinsufficient, and cardiac-specific RhoE overexpression mice. Cardiac function and inflammation in the first week post MI are assessed in mice receiving left anterior descending artery (LAD) ligation. Mechanistic study is conducted through a set of molecular signaling experiments including bimolecular fluorescence complementation (BiFC), immunoprecipitation, electrophoretic mobility shift assay and mRNA microarray analysis. Finally, we investigate the expression and clinical significance of RhoE in MI patients. Results: RhoE is upregulated in mouse post MI. RhoE deletion leads to upregulation of pro-inflammatory genes in mouse embryo heart. RhoE haploinsufficiency causes excessive inflammatory response with deleterious cardiac function post MI, while RhoE overexpression restrains post-MI inflammation and preserves cardiac function and survival. Mechanistically, RhoE specifically inhibits NF- κB activation in vivo and in vitro. RhoE binds to p65 and p50 individually in cytosol, blocking their dimerization and nuclear translocation. Consistent with findings in the mouse MI model, MI patients with higher RhoE expression show diminished cardiac inflammation and consequently a better prognosis. Conclusions: This study identified RhoE as a fine-tuning factor modulating post-MI inflammation. RhoE expression level in heart positively correlates with the outcomes of MI patients. Impact: The discovery of RhoE provides a potential therapeutic target for MI. RhoE abundance in the heart post-MI might be used for prognosis assessment.