MicroRNA-150 inhibits expression of adiponectin receptor 2 and is a potential therapeutic target in patients with chronic heart failure

Background Adiponectin is an anti-inflammatory adipocytokine believed to be involved in the pathogenesis of chronic heart failure (CHF). We aimed to characterize the expression of adiponectin and its receptors in CHF and to assess the impact of microRNAs on the cardiac adiponectin system. Methods Expression of adiponectin and adiponectin receptors (ADIPOR1 and ADIPOR2) was studied by qPCR and immunohistochemistry in myocardial tissues of patients with end-stage CHF and control subjects. MicroRNA binding was evaluated by cloning of an ADIPOR2 3´-untranslated-region reporter construct and subsequent transfection experiments. Effects of miRNA transfection were analyzed in cardiomyocyte cell cultures by qPCR and Western blotting. Gene silencing of ADIPOR2 was performed by siRNA transfection, and the effects of hypoxia/serum starvation were analyzed by flow cytometry. Results Although CHF patients displayed elevated plasma adiponectin levels, myocardial adiponectin expression generally was very low. In CHF, cardiac ADIPOR1 expression increased by >4-fold, whereas the increase in ADIPOR2 was less than 2-fold. Reporter gene assays on constructs containing the ADIPOR2-3′-untranslated region suggest that microRNA-150 specifically repressed ADIPOR2 expression. Transfection of cardiomyocytes with premiR-150 precursor molecules resulted in 60% down-regulation of ADIPOR2 mRNA and a significant reduction of ADIPOR2 protein expression. MicroRNA-150 was substantially expressed in both normal and CHF myocardium, with a 1.7-fold higher expression in CHF. Finally, knock-down experiments elucidated a stress-protective role of ADIPOR2 in cardiomyocytes. Conclusions MicroRNA-150 counteracts ADIPOR2 up-regulation in CHF and thus may contribute to adiponectin resistance. Targeting microRNA-150 may be a future strategy to restore cardioprotective adiponectin effects.