Sustained elevation of sympathetic activity is an important contributor to pathological cardiac hypertrophy, ventricular arrhythmias, and left ventricular contractile dysfunction in chronic heart failure. The orphan nuclear receptor NR4A2 is an immediate early response gene activated in the heart under beta-adrenergic stimulation. The goal of this study was to identify the transcriptional remodeling events induced by increased NR4A2 expression in cardiomyocytes, and their impact on the physiological response of those cells to sustained beta-adrenergic stimulation. Treatment of adult rat ventricular myocytes (ARVMs) with isoproterenol induced a rapid (< 4 hours) increase in NR4A2 levels that was accompanied by a transient (< 24 hours) increase in nuclear localization of the transcription factor. Adenovirus-mediated overexpression of NR4A2 to similar levels modulated the expression of genes linked to adrenoceptor signaling, calcium signaling, cell growth and proliferation, and counteracted the increase in protein synthesis rate and cell surface area mediated by chronic isoproterenol stimulation. In consistence with those findings, NR4A2 overexpression also blocked the phosphorylative activation of growth-related kinases ERK1/2, Akt, and p70S6K. Prominent among the transcriptional changes induced by NR4A2 was the up-regulation of the dual-specificity phosphatases DUSP2 and DUSP14, two known inhibitors of ERK1/2. Pre-treatment of NR4A2 overexpressing cardiomyocytes with the DUSPs inhibitor BCI prevented the inhibition of ERK1/2 following isoproterenol stimulation. In conclusion, our results suggest that NR4A2 acts as a novel negative feedback regulator of the beta-adrenergic receptor-mediated growth response in cardiomyocytes, and this at least partly through DUSP-mediated inhibition of ERK1/2 signaling. Read more »