Set7 deletion attenuates isoproterenol-induced cardiac fibrosis and prevents heart failure

The Set7 methyltransferase regulates the expression of several genes through the methylation of histones and modulates the activity of non-histone proteins. However, the role of Set7 in cardiac remodeling and heart failure remains unknown. To address this question, wild type (WT) and Set7 knockout (KO) male mice were injected with isoproterenol (60 mg/kg) or saline subcutaneously for 14 days. WT mice injected with isoproterenol displayed a decrease in Set7 activity in the heart, although Set7 protein levels were unchanged. WT and Set7 KO mice injected with isoproterenol exhibited an increase in the heart weight and cardiomyocyte area compared to their respective controls. However, Set7 KO mice displayed an exacerbated cardiac hypertrophy in response to isoproterenol compared to WT mice. In addition, Set7 deletion attenuated isoproterenol-induced cardiac fibrosis. Echocardiograms revealed that WT mice injected with isoproterenol had lowered ejection fractions and fractional shortening, and increased E/A ratios compared to their controls. Conversely, Set7 KO mice did not show alteration in these parameters in response to isoproterenol. Both isoproterenol and Set7 deletion changed the transcriptional profile of the heart. Moreover, Set7 deletion increased the expression of mitochondrial biogenesis and antioxidant factors in the heart and reduced the expression of cellular senescence and inflammation markers. Taken together, our data suggest that Set7 deletion reduces isoproterenol-induced myocardial fibrosis and prevents heart failure, suggesting that Set7 plays an important role in cardiac remodeling and function.