Department of Prevention and Health Care, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou 510630, China.
Department of Medical Oncology, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou 510630, China.
Biosci Rep. 2019 Aug 19;39(8). doi: 10.1042/BSR20190210. Print 2019 Aug 30.
Long noncoding RNA (lncRNA) maternally expressed gene 3 (MEG3) plays an important role in protection of ischemia-reperfusion (I/R) injury in brain and liver. However, role of MEG3 in myocardial I/R injury remains unclear. Here, the role of MEG3 in protection of myocardial I/R injury and its association with microRNA-7-5p (miR-7-5p) was investigated using rat cardiac I/R model and myocardial I/R cell model. Our results showed that MEG3 was significantly up-regulated and miR-7-5p was significantly down-regulated after I/R. Following I/R, the levels of intact PARP and intact caspase-3 were reduced, while the cleaved fragments of PARP and caspase-3 were increased. TUNEL assay showed an increase in cardiomyocyte apoptosis after I/R. The levels of I/R-induced creatine kinase (CK) and lactate dehydrogenase (LDH) were inhibited by knockdown of MEG3 (siMEG3). SiMEG3 increased cell proliferation and inhibited cell apoptosis after I/R. In contrast, overexpression of MEG3 increased the I/R-induced CK and LDH activities and cell apoptosis and decreased cell proliferation. The dual-luciferase reporter system showed a direct binding of MEG3 to miR-7-5p. The level of miR-7-5p was negatively associated with the change in levels of MEG3 in H9c2 cells. The levels of intact RARP1 and caspase-3 were significantly increased by knockdown of MEG3. Co-transfection of miR-7-5p inhibitor with siMEG3 activates CK and LDH, significantly decreased cell proliferation, increased cell apoptosis, and decreased intact poly(ADP-ribose) polymerase 1 (PARP1) and caspase-3. In summary, down-regulation of MEG3 protects myocardial cells against I/R-induced apoptosis through miR-7-5p/PARP1 pathway, which might provide a new therapeutic target for treatment of myocardial I/R injury.
长链非编码 RNA（lncRNA）母系表达基因 3（MEG3）在脑和肝的缺血再灌注（I/R）损伤保护中发挥重要作用。然而，MEG3 在心肌 I/R 损伤中的作用尚不清楚。本研究采用大鼠心肌 I/R 模型和心肌 I/R 细胞模型，探讨了 MEG3 在心肌 I/R 损伤保护中的作用及其与 microRNA-7-5p（miR-7-5p）的关系。结果显示，I/R 后 MEG3 明显上调，miR-7-5p 明显下调。I/R 后，完整 PARP 和完整 caspase-3 的水平降低，而 PARP 和 caspase-3 的裂解片段增加。TUNEL 检测显示 I/R 后心肌细胞凋亡增加。MEG3 敲低（siMEG3）抑制 I/R 诱导的肌酸激酶（CK）和乳酸脱氢酶（LDH）水平。siMEG3 增加 I/R 后细胞增殖，抑制细胞凋亡。相反，过表达 MEG3 增加 I/R 诱导的 CK 和 LDH 活性和细胞凋亡，减少细胞增殖。双荧光素酶报告系统显示 MEG3 与 miR-7-5p 直接结合。H9c2 细胞中 MEG3 水平的变化与 miR-7-5p 的变化呈负相关。siMEG3 下调显著增加完整 RARP1 和 caspase-3 的水平。miR-7-5p 抑制剂与 siMEG3 共转染可激活 CK 和 LDH，显著降低细胞增殖，增加细胞凋亡，减少完整多聚（ADP-核糖）聚合酶 1（PARP1）和 caspase-3。综上所述，MEG3 的下调通过 miR-7-5p/PARP1 通路保护心肌细胞免受 I/R 诱导的凋亡，为心肌 I/R 损伤的治疗提供了新的靶点。
