Requirement of IP3 receptor 3 (IP3R3) in nitric oxide induced cardiomyocyte differentiation of mouse embryonic stem cells

• The IP3 receptors (IP3Rs) are required for NO-induced Ca2+ releases from ER in mouse ES cells.
• IP3R3-mediated Ca2+ mobilization is required for the NO induced CM differentiation of mouse ES cells.
• The IP3Rs are required for the rythymatic beating of CMs derived from ES cells.

Nitric oxide (NO) markedly induces cardiomyocyte (CM) differentiation of embryonic stem (ES) cells. Here we examined the role of the Ca2+ signaling in the NO-induced CM differentiation of mouse ES cells. We found that NO induced intracellular Ca2+ increases in ES cells in a dose-dependent manner, and application of IP3 pathway antagonists not only significantly inhibited this induced Ca2+ increase but also abolished NO-induced CM differentiation of ES cells. Subsequently, all 3 types of inositol 1, 4, 5-trisphosphate (IP3) receptors (IP3Rs) in mouse ES cells were individually or triply knocked down. Interestingly, only knockdown of type 3 IP3R (IP3R3) or triple-knockdown of three types of IP3Rs significantly inhibited the NO-induced Ca2+ increases. Consistently, IP3R3 knockdown blocked the NO-induced CM differentiation of ES cells. CMs derived from IP3R3 knockdown ES cells also showed both structural and functional defects. In summary, our results indicate that the IP3R3-Ca2+ pathway is required for NO-induced CM differentiation of ES cells.