Circ-RHOJ.1 regulated myocardial cell proliferation and apoptosis via targeting the miR-124-3p/NRG-1 axis in myocardial ischemia/reperfusion injury

INTRODUCTION: Myocardial ischemia/reperfusion (I/R) injury is a leading cause of cardiac dysfunction. Circular RNAs (circRNAs) are involved in the pathogenesis of myocardial I/R injury. However, the functions and underlying mechanisms are unclear. The present study determined the role of circ-RHOJ.1 in regulating myocardial cell proliferation and apoptosis after I/R injury. MATERIAL AND METHODS: Myocardial cells isolated from Sprague-Dawley rats were identified with an immunofluorescence assay using cardiac troponin T antibody. Expression of circ-RHOJ.1, miR-124-3p and neuregulin-1 (NRG1) mRNA was assessed with real-time quantitative polymerase chain reaction. NRG1 protein expression was evaluated with western blot and immunofluorescence assays. Dual-luciferase reporter assay was performed to confirm interaction between miR-124-3p and circ-RHOJ.1, and miR-124-3p and NRG1. Effects of circ-RHOJ.1 overexpression or miR-124-3p inhibition on cell proliferation and apoptosis were evaluated using cell counting kit (CCK)-8 assay and flow cytometry. Cytokines levels were analyzed with an enzyme-linked immunosorbent assay. RESULTS: Myocardial cells were successfully isolated and had down-regulated expression of circ-RHOJ.1 and NRG1, and up-regulated expression of miR-124-3p after I/R injury. circ-RHOJ.1 acted as a sponge for miR-124-3p, and NRG1 served as a target gene of miR-124-3p. circ-RHOJ.1 overexpression or miR-124-3p inhibition increased interleukin (IL)-10 levels and reduced IL-2, IL-6, and tumor necrosis factor-α levels in myocardial cells after I/R injury. Functional assay results illustrated that circ-RHOJ.1 overexpression or miR-124-3p inhibition enhanced proliferation and inhibited apoptosis of myocardial cells after I/R injury. CONCLUSIONS: Circ-RHOJ.1 served as a molecular marker of myocardial I/R injury via regulation of miR-124-3p and NRG1 expression.