Over-expression of microRNA-145 drives alterations in β-adrenergic signaling and attenuates cardiac remodeling in heart failure post myocardial infarction.

BACKGROUND

Numerous studies have highlighted the crucial role of microRNA-145 (miR-145) in coronary atherosclerosis and myocardial ischemia reperfusion injury. However, effects of miR-145 on β-adrenergic signaling and cardiac remodeling in heart failure (HF) remains unclarified.

METHODS AND RESULTS

We established HF model in rats with left anterior descending coronary artery (LAD) occlusion. Four weeks after LAD ligation, rats showed substantial aggravation of cardiac dilation and electrophysiological instability. Up-regulation of miR-145 ameliorated HF-induced myocardial fibrosis and prolonged action potential duration. Echocardiography revealed increased basal contractility and decreased left ventricular inner-diameter in miR-145 over-expressed heart, while cardiac response to β-adrenergic receptor (βAR) stimulation was reduced. Furthermore, miR-145 increased L-type calcium current (I) density while decreased I response to β-adrenergic stimulation with isoproterenol. The alterations in βAR signaling might be predominant due to miR-145-mediated activation of Akt/CREB cascades. At high frequency pacing, Ca transient, cell shortening and frequency of Ca waves were significantly improved in AD-miR-145 group. Western blotting revealed that increased expression of Ca1.2, Ca-ATPase, β2AR, GNAI3 and decreased level of CaMKII might be attributed to the cardioprotective effects of miR-145.

CONCLUSION

miR-145 effectively alleviates HF-related cardiac remodeling by improving cardiac dilation, fibrosis, intracellular Ca mishandling and electrophysiological instability.