Cardiomyocyte differentiation from iPS cells is delayed following knockout of Bcl-2

Abstract Anti-apoptotic B-cell lymphoma 2 (Bcl-2) regulates a wide array of cellular functions involved in cell death, cell survival decisions and autophagy. Bcl-2 acts by both direct interaction with different components of the pathways involved and by intervening in intracellular Ca2+ signalling. The function of Bcl-2 is in turn regulated by post-translational modifications including phosphorylation at different sites by various kinases. Besides functions in cell death and apoptosis, Bcl-2 regulates cell differentiation processes, including of cardiomyocytes, although the signalling pathways involved are not fully elucidated. To further address the role of Bcl-2 during cardiomyocyte differentiation, we investigated the effect of its genetic knockout by CRISPR/Cas9 on the differentiation and functioning of human induced pluripotent stem cells to cardiomyocytes. Our results indicate that differentiation of iPS cells to cardiomyocytes is delayed by Bcl-2 KO, resulting in reduced size of spontaneously beating cells and reduced expression of cardiomyocyte Ca2+ toolkit and functionality. These data thus indicate that Bcl-2 an essential protein for cardiomyocyte generation.