CircHIPK3 aggravates myocardial ischemia-reperfusion injury by binding to miRNA-124-3p.

OBJECTIVE:To elucidate whether circHIPK3 could inhibit proliferation and induce apoptosis of cardiomyocytes via binding to miRNA-124-3p, thus aggravating myocardial ischemia/reperfusion (IR) injury. MATERIALS AND METHODS:CircHIPK3 expression in HCM cells simulated with myocardial I/R was determined by quantitative Real (qRT-PCR). Influences of circHIPK3 on myocardial injury marker levels of lactate dehydrogenase (LDH), malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) in the in vitro model of myocardial I/R were evaluated using the relative commercial kits. The regulatory effects of circHIPK3 on proliferative ability and apoptosis of simulated HCM cells were examined by Cell Counting Kit-8 (CCK-8) assay and flow cytometry, respectively. Dual-Luciferase reporter gene assay was conducted to verify the binding of circHIPK3 to miRNA-124-3p. Finally, the roles of the circHIPK3/miRNA-124-3p axis in regulating apoptotic gene expressions and cardiomyocyte repair after myocardial I/R were explored. RESULTS:CircHIPK3 was highly expressed in HCM cells with simulated myocardial I/R relative to those with normoxic treatment. The overexpression of circHIPK3 in simulated HCM cells decreased levels of LDH, SOD and GSH-PX, whereas increased the MDA level. Inhibited proliferation and accelerated apoptosis were observed in simulated HCM cells overexpressing circHIPK3. Western blot analyses illustrated that circHIPK3 overexpression upregulated pro-apoptotic Bax, and downregulated anti-apoptotic Bcl-2. Subsequently, we confirmed the binding between circHIPK3 and miRNA-124-3p. Rescue experiments demonstrated that circHIPK3 overexpression reversed the protective effects of miRNA-124-3p on myocardial I/R and cardiomyocyte apoptosis. CONCLUSIONS:CircHIPK3 inhibits proliferative ability and induces apoptosis of cardiomyocytes after myocardial I/R injury by binding to miRNA-124-3p, which may serve as a potential therapeutic target for I/R.

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