Downregulating miR-217-5p could protect cardiomyocytes against ischemia/reperfusion (I/R) injury, but its role in restoring mitochondrial function of I/R-injured cardiomyocytes remained unclear. H9C2 cardiomyocyte-derived cell line with I/R injury was established in vitro on the basis of hypoxia/reperfusion (H/R) model. Cell viability and apoptosis were respectively detected by MTT assay and flow cytometry. Contents of lactate dehydrogenase (LDH) and adenosine triphosphate (ATP) were determined. Flow cytometry was performed to measure the production of reactive oxygen species (ROS) and mitochondrial membrane potential (MMP). Target gene and potential binding sites between miR-217-5p and Sirtuin1 (SIRT1) were predicted by TargetScan and confirmed by dual-luciferase reporter assay. Relative SIRT1 and expressions of autophagy-related and apoptosis-related genes were measured by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot. After I/R treatment, the viability of H9C2 cardiomyocyte-derived cell line and ATP contents were reduced, but LDH and ROS contents were increased, at the same time, cell apoptosis and the expressions of miR-217-5p, p62 and cleaved caspase-3 were increased, whereas the expressions of SIRT1, LC3 (light chain 3), PINK1 (PTEN-induced kinase 1), Parkin, Bcl-2, and c-IAP (inhibitor of apoptosis protein) were reduced. However, downregulating miR-217-5p expression reversed the effects of I/R. SIRT1 was predicted and verified to be the target of miR-217-5p, and silencing SIRT1 reversed the effects of downregulating miR-217-5p on I/R-injured cells. Downregulating miR-217-5p could help restore mitochondrial function via targeting SIRT1, so as to protect cardiomyocytes against I/R-induced injury.

下调 miR-217-5p 可以保护心肌细胞免受缺血/再灌注 (I/R) 损伤，但其在恢复 I/R 损伤心肌细胞线粒体功能中的作用仍不清楚。体外建立具有I/R损伤的H9C2心肌细胞来源基于缺氧/再灌注（H/R）模型。MTT法和流式细胞术分别检测细胞活力和凋亡。测定乳酸脱氢酶（LDH）和三磷酸腺苷（ATP）的含量。进行流式细胞术以测量活性氧 (ROS) 和线粒体膜电位 (MMP) 的产生。目标基因和 miR-217-5p 和 Sirtuin1 (SIRT1) 之间的潜在结合位点由 TargetScan 预测并通过双荧光素酶报告基因检测确认。通过定量实时聚合酶链反应 (qRT-PCR) 和蛋白质印迹测量相对 SIRT1 和自噬相关和凋亡相关基因的表达。I/R 处理后，H9C2 心肌细胞株的活力和ATP 含量降低，但LDH 和ROS 含量增加，同时，细胞凋亡和 miR-217-5p、p62 和 cleaved caspase-3 的表达增加，而 SIRT1、LC3（轻链 3）、PINK1（PTEN 诱导的激酶 1）、Parkin、Bcl-2 和c-IAP（凋亡蛋白抑制剂）减少。然而，下调 miR-217-5p 表达逆转了 I/R 的影响。SIRT1 被预测并证实是 miR-217-5p 的靶点，沉默 SIRT1 逆转了下调 miR-217-5p 对 I/R 损伤细胞的影响。下调 miR-217-5p 有助于恢复线粒体功能 下调 miR-217-5p 表达逆转了 I/R 的影响。SIRT1 被预测并证实是 miR-217-5p 的靶点，沉默 SIRT1 逆转了下调 miR-217-5p 对 I/R 损伤细胞的影响。下调 miR-217-5p 有助于恢复线粒体功能 下调 miR-217-5p 表达逆转了 I/R 的影响。SIRT1 被预测并证实是 miR-217-5p 的靶点，沉默 SIRT1 逆转了下调 miR-217-5p 对 I/R 损伤细胞的影响。下调 miR-217-5p 有助于恢复线粒体功能通过靶向 SIRT1，从而保护心肌细胞免受 I/R 诱导的损伤。