Wang Xiaohui, Ha Tuanzhu, Hu Yuanping, Lu Chen, Liu Li, Zhang Xia, Kao Race, Kalbfleisch John, Williams David, Li Chuanfu
Department of Surgery, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, USA.
Center of Excellence for Inflammation, Infectious Disease and Immunity, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, USA.
Oncotarget. 2016 Dec 27;7(52):86926-86936. doi: 10.18632/oncotarget.13494.
Myocardial apoptosis plays an important role in myocardial ischemia/reperfusion (I/R) injury. Activation of PI3K/Akt signaling protects the myocardium from I/R injury. This study investigated the role of miR-214 in hypoxia/reoxygenation (H/R)-induced cell damage in vitro and myocardial I/R injury in vivo.
H9C2 cardiomyoblasts were transfected with lentivirus expressing miR-214 (LmiR-214) or lentivirus expressing scrambled miR-control (LmiR-control) respectively, to establish cell lines of LmiR-214 and LmiR-control. The cells were subjected to hypoxia for 4 h followed by reoxygenation for 24 h. Transfection of LmiR-214 suppresses PTEN expression, significantly increases the levels of Akt phosphorylation, markedly attenuates LDH release, and enhances the viability of the cells subjected to H/R. In vivo transfection of mouse hearts with LmiR-214 significantly attenuates I/R induced cardiac dysfunction and reduces I/R-induced myocardial infarct size. LmiR-214 transfection significantly attenuates I/R-induced myocardial apoptosis and caspase-3/7 and caspase-8 activity. Increased expression of miR-214 by transfection of LmiR-214 suppresses PTEN expression, increases the levels of phosphorylated Akt, represses Bim1 expression and induces Bad phosphorylation in the myocardium. In addition, in vitro data shows transfection of miR-214 mimics to H9C2 cells suppresses the expression and translocation of Bim1 from cytosol to mitochondria and induces Bad phosphorylation.
Our in vitro and in vivo data suggests that miR-214 protects cells from H/R induced damage and attenuates I/R induced myocardial injury. The mechanisms involve activation of PI3K/Akt signaling by targeting PTEN expression, induction of Bad phosphorylation, and suppression of Bim1 expression, resulting in decreases in I/R-induced myocardial apoptosis.
心肌细胞凋亡在心肌缺血/再灌注（I/R）损伤中起重要作用。PI3K/Akt信号通路的激活可保护心肌免受I/R损伤。本研究探讨了miR-214在体外缺氧/复氧（H/R）诱导的细胞损伤及体内心肌I/R损伤中的作用。
分别用表达miR-214的慢病毒（LmiR-214）或表达乱序miR对照的慢病毒（LmiR-control）转染H9C2心肌成纤维细胞，建立LmiR-214和LmiR-control细胞系。细胞先缺氧4小时，然后复氧24小时。转染LmiR-214可抑制PTEN表达，显著增加Akt磷酸化水平，明显减弱LDH释放，并增强H/R处理细胞的活力。用LmiR-214对小鼠心脏进行体内转染可显著减轻I/R诱导的心脏功能障碍，并减小I/R诱导的心肌梗死面积。LmiR-214转染可显著减轻I/R诱导的心肌细胞凋亡以及caspase-3/7和caspase-8活性。通过转染LmiR-214增加miR-214的表达可抑制PTEN表达，增加磷酸化Akt水平，抑制心肌中Bim1表达并诱导Bad磷酸化。此外，体外数据显示，将miR-214模拟物转染至H9C2细胞可抑制Bim1的表达及其从细胞质向线粒体的转位，并诱导Bad磷酸化。
我们的体外和体内数据表明，miR-214可保护细胞免受H/R诱导的损伤，并减轻I/R诱导的心肌损伤。其机制包括通过靶向PTEN表达激活PI3K/Akt信号通路、诱导Bad磷酸化以及抑制Bim1表达，从而减少I/R诱导的心肌细胞凋亡。
