Abstract 17066: Cellular Repressor of E1A-Stimulated Genes Protects From Myocardial Ischemia/Reperfusion Injury by Regulating Myocardial Autophagy and Apoptosis

Abstract

Background: Cellular repressor of E1A-stimulated genes (Creg) is a secreted glycoprotein that regulates tissue and cell homeostasis and has been shown to antagonize heart injury; however, little is known about the role of CREG in ischemia/reperfusion injury (IRI). In this study, we aimed to investigate the role of CREG in cardiac IRI and clarify the mechanism. Methods: Myocardial ischemia/reperfusion (MIR) was established by ligation of left descending coronary artery for 30 min in wild type C57 mice (Creg+/+) and heterozygous Creg mice (Creg+/–). Expression of CREG was determined by Western Blot. Infarction size was determined by TTC and Evan’s Blue staining 24 hours after MIR. Cardiac function was evaluated by echocardiography at day 28. Recombinant CREG protein (0.3mg/kg·d) was supplemented through micro-pump embedded subcutaneously in Creg+/+ mice. Cardiac function and infarction size were assessed as mentioned above. Apoptosis, lysosome formation and function were detected in both heart tissue and cardiomyocyte cell line H9C2. Results: Level of CREG protein in mouse hearts was downregulated after mice were subjected to MIR, especially in Creg+/– mice. Creg+/– mice had larger infarction sizes after 24 hours of MIR treatment and worse cardiac function at day 28 compared with Creg+/+ mice. However, cardiac function was significantly improved in Creg+/+ mice treated with recombinant CREG protein. In Creg+/– mice, the number of cardiomyocytes undergoing apoptosis was increased, and LC3A and p62 accumulated, suggesting that autophagy was dysfunctional. Upregulation of CREG decreased apoptosis and activated autophagy of cardiomyocytes. Furthermore, we demonstrated that CREG protects cardiomyocytes against apoptosis by activating autophagy both in vivo and in vitro. Conclusions: CREG overexpression protects cardiac function against IRI by preventing cardiomyocyte apoptosis. The protective effects of CREG are partly mediated by activation of lysosomal autophagy.