Identification of Cpeb4 binders in cardiomyocyte

Mutations or decreased expression of RNA-binding proteins (mRBPs) can lead to cardiomyopathies in humans. Here we defined RBPs in healthy and diseased primary cardiomyocytes at a system-wide level by RNA Interactome Capture. This identified 67 novel cardiomyocyte specific RBPs including several contractile proteins. Furthermore, we identified Cytoplasmic polyadenylation element binding protein 4 (Cpeb4) as a dynamic mRBP in diseased cardiomyocytes, regulating cardiac growth both in vitro and in vivo. To study Cpeb4 in cardiomyocytes, we identified mRNAs bound to and regulated by Cpeb4. Cpeb4 regulates cardiac remodeling by differential expression of transcription factors. Among Cpeb4 target mRNAs, two Zinc finger transcription factors (Zeb1 and Zbtb20) were identified. We show that Cpeb4 regulates the translation of these mRNAs and that Cpeb4 depletion increases their expression. Thus, Cpeb4 emerges as critical regulator of cardiomyocyte function by differential binding of specific mRNAs in response to pathological growth stimulation. Purified mRNA from immunoprecipitated Cpeb4 and Input total RNA