MicroRNAs (miRNAs) and autophagy exert an important role in hypoxia/reoxygenation (H/R)-induced cardiomyocyte injury. The current study aimed to explore the role of miRNA and autophagy in H/R-induced cardiomyocyte injury. Cardiomyocyte H9c2 was exposed to H/R to simulate H/R injury in vitro. The differentially expressed miRNAs were identified using quantitative RT-PCR (qPCR). Lactate dehydrogenase (LDH) activity was assayed to assess H/R injury. The role of miRNA and autophagy in regulating the viability and cell apoptosis was evaluated using cell counting kit-8 (CCK-8) assay, flow cytometry (FCM), and western blot. The autophagy activation was assessed through testing the number of light chain 3 (LC3) puncta and LC3-II expression using western blot and immunofluorescence analysis. In the present study, we found that the miR-542-5p expression and the autophagy activation were significantly increased in H9c2 cells after H/R injury. Functionally, forced expression of miR-542-5p further aggravated H/R injury in H9c2 cells, whereas miR-542-5p inhibition alleviated H/R injury as measured by the cell viability, LDH activity and cell apoptosis. miR-542-5p repressed autophagy activation, whereas miR-542-5p inhibition facilitated autophagy activation in H9c2 cells exposed to H/R as measured by the LC3 puncta number, LC3II, and p62 protein level. Especially, autophagy inhibition by specific inhibitor partially lessened the role of miR-542-5p inhibitor in alleviating H/R injury. Finally, the autophagy-related 7 (ATG7) was identified as a novel target gene of miR-542-5p in H9c2 cells. The current data suggest that miR-542-5p/autophagy pathway might be a potential target for the treatment of H/R-related heart diseases.

MicroRNA (miRNA) 和自噬在缺氧/复氧 (H/R) 诱导的心肌细胞损伤中发挥重要作用。本研究旨在探讨miRNA和自噬在H/R诱导的心肌细胞损伤中的作用。将心肌细胞 H9c2 暴露于 H/R 以模拟体外 H/R 损伤。使用定量 RT-PCR (qPCR) 鉴定差异表达的 miRNA。测定乳酸脱氢酶 (LDH) 活性以评估 H/R 损伤。使用细胞计数试剂盒-8 (CCK-8) 测定、流式细胞术 (FCM) 和蛋白质印迹评估 miRNA 和自噬在调节活力和细胞凋亡中的作用。通过使用蛋白质印迹和免疫荧光分析测试轻链 3 (LC3) 点的数量和 LC3-II 表达来评估自噬激活。在本研究中，我们发现H/R损伤后H9c2细胞中miR-542-5p表达和自噬激活显着增加。从功能上讲，miR-542-5p的强制表达进一步加剧了H9c2细胞中的H/R损伤，而通过细胞活力、LDH活性和细胞凋亡测量，miR-542-5p抑制减轻了H/R损伤。通过 LC3 斑点数、LC3II 和 p62 蛋白水平测量，在暴露于 H/R 的 H9c2 细胞中，miR-542-5p 抑制自噬激活，而 miR-542-5p 抑制促进自噬激活。特别是，特定抑制剂的自噬抑制部分减弱了 miR-542-5p 抑制剂减轻 H/R 损伤的作用。最后，自噬相关7（ATG7）被确定为H9c2细胞中miR-542-5p的新靶基因。目前的数据表明miR-542-5p/自噬通路可能是治疗H/R相关心脏病的潜在靶点。