Ischemia/reperfusion (I/R) injury is one of the major causes of cardiovascular disease. Gypenoside A (GP), the main active component of Gynostemma pentaphyllum, alleviates myocardial I/R injury. Circular RNAs (circRNAs) and microRNAs (miRNAs) are involved in the I/R injury. We explored the protective effect of GP on human cardiomyocytes (HCMs) via the circ_0010729/miR-370-3p/RUNX1 axis. Overexpression of circ_0010729 abolished the effects of GP on HMC, such as suppression of apoptosis and increase in cell viability and proliferation. Overexpression of miR-370-3p reversed the effect of circ_0010729 overexpression, resulting in the stimulation of HMC viability and proliferation and inhibition of apoptosis. The knockdown of miR-370-3p suppressed the effects of GP in HCMs. RUNX1 silencing counteracted the effect of miR-370-3p knockdown and maintained GP-induced suppression of apoptosis and stimulation of HMC viability and proliferation. The levels of RUNX1 mRNA and protein were reduced in cells expressing miR-370-3p. In conclusion, this study confirmed that GP alleviated the I/R injury of myocardial cell via the circ_0010729/miR-370-3p/RUNX1 axis.

Ischemia-reperfusion (I/R) is an important risk factor for cardiovascular diseases (CVDs) and cardiac transplantation, as I/R can cause myocardial cell hypoxia/reoxygenation (H/R) injury. Recent research has shown that circular RNAs (circRNAs) may affect the progress of H/R-induced myocardial injury, but the mechanism remains unknown. Our work explored the role of circ_0010729 in H2O2-induced myocardial injury.
The levels of circ_0010729, microRNA-1184 (miR-1184) and mRNA of receptor interacting serine/threonine kinase 1 (RIPK1) were indicated by quantitative real-time polymerase chain reaction (qRT-PCR) in human cardiac myocytes (HCMs). Meanwhile, the protein level of RIPK1 was quantified by western blot analysis. Besides, the cell functions were examined by 5-Ethynyl-29-deoxyuridine (EdU) assay, flow cytometry assay, western blot and antioxidant indexes analysis. Furthermore, the interplay between miR-1184 and circ_0010729 or RIPK1 was detected by dual-luciferase reporter assay. Eventually, the in vivo experiments were applied to measure the role of circ_0010729.
The levels of circ_0010729 RNA and RIPK1 protein were increased, and the miR-1184 was decreased in HCMs exposed to H2O2. In functional analysis, circ_0010729 deficiency restrained cell apoptosis and oxidative stress, whereas promoted cell proliferation in HCMs under H2O2 exposure. Moreover, miR-1184 inhibited the H2O2-induced myocardial injury by targeting RIPK1. Mechanistically, circ_0010729 acted as a miR-1184 sponge to regulate the level of RIPK1.
Circ_0010729 promotes H2O2-induced myocardial injury, and thus circ_001729 may be targeted as a potential therapy for H/R-induced myocardial injury.

Few studies have addressed the mechanism by which circ_0010729 regulates hypoxia-induced cell injury in cardiovascular diseases. However, its role and its regulatory mechanism in myocardial infarction remain to be explored. Cell viability, cycle, apoptosis, and migration were analyzed using cell counting kit-8 assay, flow cytometry, caspase-3 activity assay kit and transwell assay, respectively. Tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) concentrations were examined by enzyme-linked immunosorbent assay. Glucose metabolism was calculated by detecting ATP production, glucose uptake and lactate production. Levels of circ_0010729, miR-370-3p and TNF Receptor Associated Factor 6 (TRAF6) were detected using quantitative real-time polymerase chain reaction or western blot. The direct interaction between circ_0010729 and TRAF6 or miR-370-3p was verified using dual-luciferase reporter assay and RNA immunoprecipitation assay. Under hypoxia condition, cardiomyocytes suffered from cell viability suppression, cell cycle arrest, cell apoptosis promotion, migration reduction, increase of inflammatory factor IL-6 and TNF-α, as well as glycolysis inhibition. Circ_0010729 expression was up-regulated in the cardiomyocytes at different hypoxia-exposed time points. Circ_0010729 knockdown protected cardiomyocytes against hypoxic dysfunction, while circ_0010729 overexpression showed inverse effects. MiR-370-3p was confirmed to directly bind to circ_0010729 or TRAF6. MiR-370-3p inhibition attenuated the protective effects of circ_0010729 knockdown on hypoxia-modulated cardiomyocyte dysfunction. MiR-370-3p restoration protected cardiomyocytes against hypoxic injury via targeting TRAF6. Besides, circ_0010729 indirectly regulated TRAF6 expression via miR-370-3p. This study demonstrated that circ_0010729 knockdown attenuated hypoxia-induced cardiomyocyte dysfunction via miR-370-3p/TRAF6 axis, indicating a potential therapeutic target for myocardial infarction.

Ischemic cardiomyopathy is a severe cardiovascular disease with high mortality. Circular RNAs (circRNAs) are widely regulated in diverse human diseases, including Ischemic cardiomyopathy. This study aimed to investigate a novel functional mechanism of circRNA circ_0010729 in hypoxia-induced cardiomyocyte injuries. Human cardiomyocytes (AC16) were exposed to hypoxia to mimic ischemic cardiomyopathy in vitro. Cell viability, apoptosis/necrosis and glycolysis progress, were determined using 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay, flow cytometry assay and glycolysis stress test, respectively. Cell apoptosis was also assessed by the activity of cleaved caspase-3/7. The levels of glycolysis-related proteins and tumor necrosis factor receptor-associated factor 5 (TRAF5) were examined by western blot. The expression of circ_0010729 and miR-27a-3p was measured by real-time quantitative reverse transcription-polymerase chain reaction (qRT-PCR). The prediction about the targeted relationship was verified by dual-luciferase reporter assay, RNA immunoprecipitation (RIP) assay and RNA pull-down assay. As a result, hypoxia treatment inhibited cell viability, induced cell apoptosis and blocked glycolysis, however, these injuries were alleviated by circ_0010729 knockdown. MiR-27a-3p was targeted by circ_0010729, and miR-27a-3p inhibition reversed the role of circ_0010729 knockdown, leading to the deterioration of cell injuries. Further, TRAF5 was a target of miR-27a-3p, and circ_0010729 upregulated the expression of TRAF5 by sponging miR-27a-3p. MiR-27a-3p restoration enhanced cell viability, depleted cell apoptosis and promoted glycolysis of hypoxia-induced AC16 cells, while these effects were abolished by TRAF5 overexpression. In conclusion, circ_0010729 knockdown alleviated hypoxia-induced AC16 cell injuries by mediating the miR-27a-3p/TRAF5 axis.