MicroRNA-494 Targeting Both Proapoptotic and Antiapoptotic Proteins Protects Against Ischemia/Reperfusion-Induced Cardiac Injury

Abstract

Background-MicroRNAs (miRs) participate in many cardiac pathophysiological processes, including ischemia/reperfusion (I/R)-induced cardiac injury. Recently, we and others observed that miR-494 was downregulated in murine I/R-injured and human infarcted hearts. However, the functional consequence of miR-494 in response to I/R remains unknown. Methods and Results-We generated a mouse model with cardiac-specific overexpression of miR-494. Transgenic hearts and wild-type hearts from multiple lines were subjected to global no-flow I/R with the Langendorff system. Transgenic hearts exhibited improved recovery of contractile performance over the reperfusion period. This improvement was accompanied by remarkable decreases in both lactate dehydrogenase release and the extent of apoptosis in transgenic hearts compared with wild-type hearts. In addition, myocardial infarction size was significantly reduced in transgenic hearts on I/R in vivo compared with wild-type hearts. Similarly, short-term overexpression of miR-494 in cultured adult cardiomyocytes demonstrated an inhibition of caspase-3 activity and reduced cell death on simulated I/R. In vivo treatment with antisense oligonucleotide miR-494 increased I/R-triggered cardiac injury relative to the administration of mutant antisense oligonucleotide miR-494 and saline controls. We further identified that 3 proapoptotic proteins (PTEN, ROCK1, and CaMKII␦) and 2 antiapoptotic proteins (FGFR2 and LIF) were authentic targets for miR-494. Importantly, the Akt-mitochondrial signaling pathway was activated in miR-494 -overexpressing myocytes. Conclusions-Our findings suggest that although miR-494 targets both proapoptotic and antiapoptotic proteins, the ultimate consequence is activation of the Akt pathway, leading to cardioprotective effects against I/R-induced injury. Thus, miR-494 may constitute a new therapeutic agent for the treatment of ischemic heart disease. (Circulation. 2010; 122:1308-1318.)Key Words: myocardial infarction Ⅲ apoptosis Ⅲ cardiomyocyte Ⅲ microRNA Ⅲ reperfusion injury I schemic heart disease, a leading cause of death worldwide, is the most common consequence of coronary artery disease. 1,2 Although reperfusion of an occluded human coronary is effective for reducing overall mortality, it is now recognized that restoration of the blood flow through the previously ischemic myocardium can yield additional reperfusion injury, including cardiomyocyte dysfunction and cell death. 3 The cellular mechanisms underlying ischemia/reperfusion (I/R)-induced injury are complex and involve a multitude of signaling pathways and molecular players. 4 Therefore, it would be rational to develop an effective pharmacological or genetic agent aimed at multiple molecular targets. MicroRNAs (miRs), a new class of Ϸ22-nt non-protein-coding single-strand RNAs, have emerged as regulators that control the expression of hundreds of proteins. 5 As a consequence, they may widely influence the signaling networks leading to pathological/physiological responses such as myocardial I/R inju...

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