MicroRNA-214 protects against hypoxia/reoxygenation induced cell damage and myocardial ischemia/reperfusion injury via suppression of PTEN and Bim1 expression

// Xiaohui Wang 1 , Tuanzhu Ha 1, 4 , Yuanping Hu 1 , Chen Lu 1 , Li Liu 2 , Xia Zhang 1 , Race Kao 1, 4 , John Kalbfleisch 3, 4 , David Williams 1, 4 , Chuanfu Li 1, 4 1 Department of Surgery, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, USA 2 Department of Geriatrics, First Affiliated Hospital with Nanjing Medical University, Nanjing, China 3 Department of Biometry and Medical Computing, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, USA 4 Center of Excellence for Inflammation, Infectious Disease and Immunity, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, USA Correspondence to: Chuanfu Li, email: Li@etsu.edu Keywords: microRNA-214, myocardial ischemia/reperfusion injury, myocardial apoptosis, PTEN, Bim1 Received: September 24, 2016      Accepted: October 28, 2016      Published: November 22, 2016 ABSTRACT Background: 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 . Methods and Results: 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. Conclusions: 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.