Circ_0049979 ameliorates myocardial infarction through improving Cx43-mediated endothelial functions

Endothelial injury is a fundamental pathogenesis of coronary atherosclerotic heart disease (CHD). Circular RNAs (circRNAs) are important post-transcriptional regulators in many human major diseases, including CHD. The aim of the present study was to explore the role of circ_0049979, a novel identified circRNA from ANO8 gene locus, in endothelial injury during CHD. We found that expression of circ_0049979 was reduced by ox-LDL treatment in HUVECs in a dose-dependent manner. Loss- and gain-of-function experiments demonstrated that knockdown of circ_0049979 decreased the capacities of proliferation, migration and tube formation in normal HUVECs. While, overexpression of circ_0049979 improved these capacities in both normal and ox-LDL-incubated HUVECs. Then, the online bioinformatic tool Circinteractome was used to predicted the target miRNAs of circ_0049979, and miR-653 was selected as the candidate. We demonstrated that miR-653 directly interacted with and was negatively regulated by circ_0049979, and played a negative role in regulating proliferation, migration and tube formation of HUVECs. In terms of the mechanism, miR-653 post-transcriptionally suppressed the expression of the gap junction protein 43 (Cx43), a key protein of endothelial tight junction. Finally, we verified that overexpression of circ_0049979 was able to alleviate plaque formation, lipid deposition, and endothelial cell apoptosis, as well as myocardial infarction, in coronary atherosclerotic mice in vivo. In conclusion, circ_0049979 plays a protective role in coronary atherosclerotic myocardial infarction by improving miR-653/Cx43-mediated endothelial functions.