Abstract：
This study aimed to observe the mechanism and effect of circ_0004771 on cardiomyocyte injury in acute myocardial infarction (AMI). The differences in circ_0004771 expression in the blood of AMI patients and healthy volunteers were observed by Real-Time Quantitative Reverse Transcription-Polymerase Chain Reaction. AMI cell models were constructed by hypoxia/reoxygenation (H/R)-induced injury in human cardiomyocytes (AC16 cells). The changes of circ_0004771 expression in AMI cells were observed. After transfection with the knockdown or overexpression of circ_0004771 vector in AMI cells, Cell Counting Kit-8 (CCK-8) assay and propidium iodide/FITC-Annexin V staining were performed to detect cell proliferation and apoptosis levels, extracellular lactate dehydrogenase (LDH) activity, malondialdehyde (MDA) concentration, and superoxide dismutase (SOD) activity. Expression levels of Mitogen-activated protein kinase (MAPK) signaling pathway-related proteins (p-MEK1/2, MEK1/2, p-ERK1/2, ERK1/2), and endoplasmic reticulum (ER) stress proteins (GRP78 and CHOP-1) were observed in each group of cells by western blot method. The expression level of circ_0004771 was significantly reduced in both clinical samples and cells of AMI. When circ_0004771 was knocked down in AMI cells, it resulted in a decrease in cell proliferation level and significant increase in apoptosis level. The inhibition of circ_0004771 expression caused leakage of LDH in AMI cells, accumulation of intracellular MDA, and inhibition of SOD activity. In addition, the knockdown of circ_0004771 significantly increased the levels of p-MEK1/2, p-ERK1/2, GRP78, and CHOP-1 in H/R-induced AC16 cells. However, the overexpression of circ_0004771 resulted in the opposite result as when circ_0004771 was knocked down. A low level of circ_0004771 in AMI activates the MAPK signaling pathway in cardiomyocytes as well as encourages intracellular oxidative stress and ER stress, thereby inhibiting cell proliferation and promoting apoptosis.
摘要：
本研究旨在观察circ_0004771对急性心肌梗死（AMI）心肌细胞损伤的机制和作用。通过实时定量逆转录聚合酶链反应观察AMI患者和健康志愿者血液中circ_0004771表达的差异。通过缺氧/复氧（H/R）诱导的人心肌细胞（AC16细胞）损伤建立AMI细胞模型。观察circ_0004771在AMI细胞中的表达变化。在AMI细胞中转染circ_0004771载体敲低或过表达后，细胞计数试剂盒-8(CCK-8)和碘化丙啶/FITC-膜联蛋白V染色检测细胞增殖和凋亡水平,细胞外乳酸脱氢酶（LDH）活性，丙二醛（MDA）浓度，超氧化物歧化酶(SOD)活性。丝裂原活化蛋白激酶(MAPK)信号通路相关蛋白(p-MEK1/2,MEK1/2,p-ERK1/2,ERK1/2)的表达,用westernblot方法观察各组细胞内质网（ER）应激蛋白（GRP78和CHOP-1）。circ_0004771的表达水平在AMI的临床样品和细胞中均显著降低。当circ_0004771在AMI细胞中被敲低时，它导致细胞增殖水平降低和凋亡水平显着增加。抑制circ_0004771表达导致AMI细胞LDH渗漏,细胞内MDA的积累，并抑制SOD活性。此外,circ_0004771的敲减会显著增加H/R诱导的AC16细胞中p-MEK1/2、p-ERK1/2、GRP78和CHOP-1的水平。然而,circ_0004771的过表达导致与circ_0004771被击倒时相反的结果。AMI中低水平的circ_0004771激活心肌细胞MAPK信号通路，促进细胞内氧化应激和内质网应激，从而抑制细胞增殖，促进细胞凋亡。
