Department of Cardiology, Qilu Hospital of Shandong University (Qingdao), Qingdao, Shandong 266035, P.R. China.
Cadre Health Care Department, Qingdao Municipal Hospital (Group), Qingdao No. 9 People's Hospital, Qingdao, Shandong 266000, P.R. China.
Int J Mol Med. 2018 Jul;42(1):589-596. doi: 10.3892/ijmm.2018.3628. Epub 2018 Apr 17.
Myocardial ischemia‑reperfusion (I/R) injury is a major cause of cardiovascular disease worldwide, and microRNAs have been implicated in the regulation of pathological and physiological processes in myocardial I/R injury. The present study aimed to investigate the role of microRNA (miR)‑221‑3p in myocardial I/R injury. Cell death and lactate dehydrogenase (LDH) activity were increased in hydrogen peroxide (H2O2)‑treated H9c2 cells, as measured by flow cytometry and an LDH detection kit. The expression of miR‑221‑3p was elevated in H2O2‑incubated cells and in remote areas of the rat I/R model, examined using reverse transcription‑quantitative polymerase chain reaction analysis. The overexpression of miR‑221‑3p enhanced the number of propidium iodide (PI)+ cells and the activity of LDH in H2O2‑treated cells. In I/R‑induced rats, the overexpression of miR‑221‑3p promoted the number of myosin+ cells and inhibited the fractional shortening of left ventricular diameter (FSLVD%). The results showed that the expression of p57 at the gene and protein levels was decreased in H9c2 cells incubated with H2O2 and in rats subjected to I/R surgery; the expression of p57 decreased following the overexpression of miR‑221‑3p. Subsequently, the hypothesis that p57 was the direct target of miR‑221‑3p was confirmed by performing a dual‑luciferase reporter assay. Finally, to examine the function of p57 in myocardial impairment, p57 was transfected into H9c2 cells and administered to the rats prior to undergoing H2O2 treatment and I/R surgery, respectively. The results indicated that p57 attenuated the number of PI+ cells and the activity of LDH in H2O2‑treated cells, whereas p57 downregulated the number of myosin+ cells and upregulated FSLVD% in the I/R‑treated rats. Therefore, these findings suggested that miR‑221‑3p exacerbated the H2O2‑induced myocardial damage in H9c2 cells and myocardial I/R injury in the rat model by modulating p57.
心肌缺血再灌注（I/R）损伤是全球范围内心血管疾病的主要原因，微小 RNA（miRNA）已被牵涉到心肌 I/R 损伤的病理和生理过程的调控中。本研究旨在探讨微小 RNA（miR）-221-3p 在心肌 I/R 损伤中的作用。
通过流式细胞术和乳酸脱氢酶（LDH）检测试剂盒测定，发现过氧化氢（H2O2）处理的 H9c2 细胞中细胞死亡和 LDH 活性增加。逆转录-定量聚合酶链反应分析显示，H2O2 孵育的细胞和大鼠 I/R 模型的远隔区域中 miR-221-3p 的表达升高。
miR-221-3p 的过表达增加了 H2O2 处理的细胞中碘化丙啶（PI）+细胞的数量和 LDH 的活性。在 I/R 诱导的大鼠中，miR-221-3p 的过表达促进了肌球蛋白+细胞的数量，并抑制了左心室直径的分数缩短率（FSLVD%）。结果表明，H2O2 孵育的 H9c2 细胞和接受 I/R 手术的大鼠中 p57 的基因和蛋白水平表达降低；miR-221-3p 的过表达后 p57 表达降低。随后，通过双荧光素酶报告基因检测证实了 p57 是 miR-221-3p 的直接靶基因。最后，为了研究 p57 在心肌损伤中的功能，将 p57 转染到 H9c2 细胞中，并分别在 H2O2 处理和 I/R 手术前给予大鼠。结果表明，p57 减轻了 H2O2 处理的细胞中 PI+细胞的数量和 LDH 的活性，而 p57 降低了 I/R 处理的大鼠中肌球蛋白+细胞的数量，并上调了 FSLVD%。
因此，这些发现表明 miR-221-3p 通过调节 p57 加重了 H9c2 细胞中 H2O2 诱导的心肌损伤和大鼠模型中的心肌 I/R 损伤。
