Abstract 11556: Increased Expression of Microrna-214 Protects Against Hypoxia/Reoxygenation Induced Cell Damage and Myocardial Ischemia/Reperfusion Injury via Suppression of PTEN and Phosphorylation of BAD
Toll-like receptor-4 deficiency (TLR4-/-) protects the myocardium from ischemia/reperfusion (I/R) injury. We found that myocardial microRNA-214 (miR-214) levels in TLR4-/- mice are significantly greater than in wild type mice, suggesting that miR-214 may play a protective role in myocardial I/R injury. This study evaluated the effect of increased expression of miR-214 on hypoxia/reoxygenation (H/R)-induced cell damage in vitro and myocardial I/R injury in vivo. First, we transfected H9C2 cardiomyoblasts with miR-214 mimics (n=5). Scrambled mimic served as control (n=5). H/R-induced caspase-8 activity, LDH release, and decreased cell viability were significantly attenuated by miR-214 transfection. Transfection of miR-214 mimics suppressed PTEN expression and increased the levels of phospho-Akt and phospho-BAD. Second, we transfected lentivirus expressing miR-214 (LmiR-214) into mouse hearts (n=8) through the right common carotid artery. Lentivirus expressing control miR (LmiR-Con) served as transfection control (n=8), untransfected I/R mice served as I/R control (n=9), and sham operation served as sham control (n=6/group). Seven days after transfection, the hearts were subjected to ischemia (45 min) followed by reperfusion for up to 7 days.
Cardiac function was measured by echocardiography prior to and after (3 and 7 days) myocardial I/R. LmiR-214 transfection prevented I/R-induced decreases in EF% and %FS and significantly decreased myocardial infarct size (↓ 49%).
Transfection of LmiR-Con did not alter I/R-induced cardiac dysfunction and reduce myocardial infarct size. TUNEL showed that transfection of LmiR-214 attenuated I/R-induced myocardial apoptosis (↓ 69.7%). Western blot showed that LmiR-214 transfection significantly suppressed PTEN and Bim expression and increased the levels of phospho-Akt and phospho-BAD in sham and I/R hearts compared with untransfected groups. Transfection of LmiR-control did not alter I/R-induced infarction and apoptosis as well as PTEN and BIM expression. We conclude that miR-214 protects against H/R-induced cell damage and myocardial I/R injury via activation of PI3K/Akt signaling by targeting PTEN as well as attenuation of apoptosis by targeting Bim and phosphorylating BAD.
- © 2013 by American Heart Association, Inc.