Heart Specific Deletion of RNA Binding Protein Rbfox1 Sensitizes Mice to Pressure Overload Induced Cardiac Dysfunction

Abstract

Alternative splicing increases the ability to respond to stress. One of the most important alternative splicing regulators is the family of Rbfox proteins. Rbfox1 is specifically expressed in brain, heart and skeletal muscle. Here, we generated cardiac specific Rbfox1 deletion mice using Nkx2.5‐cre (cRbfox1‐/‐), which showed depressed baseline cardiac function measured by echocardiography. We confirmed cardiomyocyte specific deletion of Rbfox1 by Western blotting and immunohistochemistry. Morphometry analysis identified a small but significant increase in cardiac hypertrophy at baseline. We next isolated adult cardiomyocytes, which showed slower calcium reuptake kinetics. To assess the role of Rbfox1 mediated alternative splicing in the cardiac stress response, we induced pressure overload by trans‐aortic constriction (TAC) in two‐month‐old WT and cRbfox1‐/‐ mice. cRbfox1‐/‐ mice showed an increased propensity to develop heart failure with depressed cardiac function. The slight increase in cardiac hypertrophy we noted at baseline was further enhanced. We further showed increased cardiomyocyte apoptosis by cleaved caspase 3 staining and cardiac fibrosis by fast green and sirius red staining. In conclusion, Rbfox1 is important to maintain cardiac function and loss of Rbfox1 function sensitizes cardiomyocytes to pressure overload induced cardiac dysfunction and cardiomyocyte apoptosis. We are currently unraveling which Rbfox1 mediated alternatively spliced genes drive these events.