Abstract
Rbfox1 is important to maintain cardiac function through regulation of alternative splicing and expression of calcium handling proteins. The heart recycles proteins and degrades them either via the ubiquitin proteasome system or through autophagy. The role of Rbfox1 in post‐translational modification (PTM) and proteasomal degradation is not known. To assess a potential role for Rbfox1 in regulating PTM and proteasomal degradation, we deleted Rbfox1 in cardiomyocytes, either by Rbfox1 gene‐deletion mice (cRbfox1−/−) or by transfecting cultured neonatal rat cardiomyocytes with Rbfox1siRNA. Cardiomyocyte specific deletion of Rbfox1 was confirmed by Western blotting and immunohistochemistry. cRbfox1−/− mice showed an overall decrease in expression of SUMO‐1 and K63‐ubiquitin conjugated proteins while K48‐Ubiquitin expression was increased. These results were confirmed in cardiomyocytes transfected with Rbfox1 siRNA, suggesting a direct role for Rbfox1 in regulating sumoylation and ubiquitination. Moreover, we measured the 20S proteasome activity and found an increase in proteasomal activity both in cRbfox1−/− mouse as well as in Rbfox1siRNA transfected cardiomyocytes. Since protein abundance is a balance between protein production and degradation, we further investigated protein synthesis. We transfected cardiomyocytes with siRNA against Rbfox1 and treated them with puromycin. Cell lysates were probed with a puromycin antibody to measure overall protein synthesis. Our results showed significant deficiency in total protein synthesis in Rbfox1 siRNA as compared with control. In conclusion, Rbfox1 is important in maintaining protein homeostasis, by controlling their production and degradation. These alterations in critical cellular processes likely predispose the heart to cardiac dysfunction.Support or Funding InformationThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
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