Abstract
Identification of factors that direct embryonic stem (ES) cell (ESC) differentiation into functional cardiomyocytes is essential for successful use of ESC-based therapy for cardiac repair. Neuregulin-1 (NRG1) and microRNA play important roles in the cardiac differentiation of ESCs. Understanding how NRG1 regulates microRNA will provide new mechanistic insights into the role of NRG1 on ESCs. It may also lead to the discovery of novel microRNAs that are important for ESC cardiac differentiation. The objective of this study was to assess the microRNA expression profile during NRG1-induced ESC cardiac differentiation. Murine ESCs were incubated with a recombinant NRG1β or an inhibitor of ErbB2 or ErbB4 during hanging drop-induced cardiac differentiation. The expression of cardiac-specific markers and microRNAs was analyzed by RT-PCR and microRNA array, respectively. We found that the expression of NRG1 and the ErbB receptors was increased during hanging drop-induced cardiac differentiation of ESCs. NRG1 stimulation during a specific developmental window enhanced, while inhibition of the ErbB2 or ErbB4 receptor inhibited, cardiac differentiation of ESCs. NRG1 increased the expression of mmu-miR-296-3p and mmu-miR-200c*, and decreased mmu-miR-465b-5p. Inhibition of mmu-miR-296-3p or mmu-miR-200c* decreased, while inhibition of mmu-miR-465-5p increased, the differentiation of ESCs into the cardiac lineage. This is the first report demonstrating that microRNAs are differentially regulated by NRG1-ErbB signaling during cardiac differentiation of ESCs. This study has also identified new microRNAs that are important for ESC cardiac differentiation.