miR-451-3p alleviates myocardial ischemia/reperfusion injury by inhibiting MAP1LC3B-mediated autophagy.

OBJECTIVE AND DESIGN: We aim to explore the molecular mechanism of myocardial ischemia-reperfusion injury (MIRI). METHODS: The H9C2 cells were cultured under hypoxia/reoxygenation (H/R) condition to induce myocardial injury in vitro. The expression of miR-451-3p and MAP1LC3B was detected by RT-qPCR. Dual-luciferase reporter assay and RNA pull-down assay were performed to examine the relationship between microRNA (miR)-451-3p and MAP1LC3B. CCK8 was used to test cell viability. The level of LDH and CK was evaluated via ELISA. Immunofluorescence assay and flow cytometry were applied to detect autophagy and apoptosis, respectively. Autophagy-related protein expressions were determined by western blotting. Furthermore, an in vivo rat model of MIRI was established by subjection to 30 min ischemia and subsequently 24 h reperfusion for validation of the role of miR-451-3p in regulating MIRI in vivo. RESULTS: miR-451-3p was down-regulated in MIRI, and miR-451-3p mimics transfection alleviated autophagy and apoptosis induced by MIRI. miR-451-3p could target MAP1LC3B directly. Co-transfection miR-451-3p mimics and pcDNA 3.1 MAP1LC3B curbed the protected effects of miR-451-3p mimics on MIRI. CONCLUSIONS: miR-451-3p played a protective role in MIRI via inhibiting MAP1LC3B-mediated autophagy, which may provide new molecular targets for the treatment of MIRI and further improves the clinical outcomes of heart diseases.

6-Gingerol relieves myocardial ischaemia/reperfusion injury by regulating lncRNA H19/miR-143/ATG7 signaling axis-mediated autophagy.

Myocardial ischemia/reperfusion injury (MIRI) causes severe damage in cardiac tissue, thereby resulting in a high rate of mortality. 6-Gingerol (6-G) is reported to play an essential role in alleviating MIRI. However, the underlying mechanism remains obscure. This study was intended to explore the potential mechanism by which 6-G functions. Q-PCR was employed to quantify the relative RNA levels of long noncoding RNA (lncRNA) H19 (H19), miR-143, and ATG7, an enzyme essential for autophagy, in HL-1 cells. Western blotting, immunofluorescence, and immunohistochemistry were employed for protein evaluation in cultured cells or mouse tissues. Cell viability, cytotoxicity, and apoptosis were analysed by CCK-8, LDH, and flow cytometry assays, respectively. The binding sites for miR-143 were predicted using starBase software and experimentally validated through a dual-luciferase reporter system. Here, we found that 6-G elevated cellular H19 expression in hypoxia/reoxygenation (H/R)-treated HL-1 cells. Moreover, 6-G increased Bcl-2 expression but reduced cleaved caspase 3 and caspase 9 protein levels. Mechanistically, H19 directly interacted with miR-143 and lowered its cellular abundance by acting as a molecular sponge. Importantly, ATG7 was validated as a regulated gene of miR-143, and the depletion of miR-143 by H19 caused an increased in ATG7 expression, which in turn promoted the autophagy process. Last, mouse experiments highly supported our in vitro findings that 6-G relieves MIRI by enhancing autophagy. The H19/miR-143/ATG7 axis was shown to be critical for the function of 6-G in relieving MIRI.

[6-Gingerol Pretreatment Alleviates Hypoxia/Reoxygenation-induced H9C2 Cardiomyocyte Injury by Inhibiting Oxidative Stress and Inflammation].

OBJETIVE: To observe the effect of 6-gingerol (6-G) pretreatment on hypoxia/reoxygenation (H/R) induced injury in H9C2 myocardial cell and investigate its related mechanism. METHODS: The H/R in vitro model of cardiomyocytes was prepared by conventional methods. In detail, H9C2 cells were added with the nitrogen-saturated hypoxic liquid, and placed in an incubator, mixed with gas (1% O 2, 5% CO 2, 94% N 2) applying for 15 min. After culturing for 3 h, the cells were taken out and placed in an incubator (37℃, 5% CO 2) for 1 h. Before establishing the cell model, the cells were pretreated with 6-G, and the cell viability was measured by MTT method to observe the protective effect of different concentrations of 6-G on H/R-induced cell damage. The 6-G mass concentration for pretreatment that led to the highest cell viability was used for follow-up experiments. DCFH-DA fluorescent probe was used to detect the effect of 6-G pretreatment on H9C2 oxidative stress level, and the intracellular oxidative stress was observed with fluorescence microscope and flow cytometry. Western blot method was used to detect the expression of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and interleukin-1ß (IL-1ß) in H/R-induced cell inflammatory responses. RESULTS: Compared with the H/R group, the cell viability of the 6-G+H/R group began to increase when the concentration of 6-G promoted to50 µg/mL. The cell viability was the highest after pretreated with 200 µg/mL 6-G. Therefore, 200 µg/mL was considered as the best 6-G intervention concentration for subsequent experiment. The content of reactive oxygen species (ROS) in the 200 µg/mL 6-G group had no significant changes compared with the control group (P>0.05), and the ROS fluorescence peak did not migrate significantly. However the ROS content in the H/R group increased significantly compared with the control (P<0.05), and the ROS fluorescence peak shifted to the right. Compared with the H/R group, the ROS content of the 6-G+H/R group decreased (P<0.05), and the ROS fluorescence peak shifted to the left. Compared with the control group, the expressions of TNF-α, IL-6, IL-1ß in the 6-G group had no significant changes (P>0.05); the expressions of TNF-α, IL-6, IL-1ß in the H/R group increased (P<0.05). Compared with H/R group, the expressions of TNF-α, IL-6 and IL-1ß in 6-G+H/R group decreased (P<0.05). CONCLUSION: 6-G pretreatment can alleviate H/R-induced H9C2 myocardial injury, which may be related to the inhibition of oxidative stress and inflammatory responses.