%0 Journal Article %T Ouabain facilitates cardiac differentiation of mouse embryonic stem cells through ERK1/2 pathway %A Lee Yee-Ki %A Ng Kwong-Man %A Lai Wing-Hon %A Man Cornelia %A Lieu Deborah K %A Lau Chu-Pak %A Tse Hung-Fat %A Siu Chung-Wah %J Acta Pharmacologica Sinica %D 2016 %B 2016 %9 %! Ouabain facilitates cardiac differentiation of mouse embryonic stem cells through ERK1/2 pathway %K %X Aim: To investigate the effects of the cardiotonic steroid, ouabain, on cardiac differentiation of murine embyronic stem cells (mESCs). Methods: Cardiac differentiation of murine ESCs was enhanced by standard hanging drop method in the presence of ouabain (20 μmol/L) for 7 d. The dissociated ES derived cardiomyocytes were examined by flow cytometry, RT-PCR and confocal calcium imaging. Results: Compared with control, mESCs treated with ouabain (20 μmol/L) yielded a significantly higher percentage of cardiomyocytes, and significantly increased expression of a panel of cardiac markers including Nkx 2.5, α-MHC, and β-MHC. The α1 and 2- isoforms Na + /K + -ATPase, on which ouabain acted, were also increased in mESCs during differentiation. Among the three MAPKs involved in the cardiac hypertrophy pathway, ouabain enhanced ERK1/2 activation. Blockage of the Erk1/2 pathway by U0126 (10 μmol/L) inhibited cardiac differentiation while ouabain (20 μmol/L) rescued the effect. Interestingly, the expression of calcium handling proteins, including ryanodine receptor (RyR2) and sacroplasmic recticulum Ca 2+ ATPase (SERCA2a) was also upregulated in ouabain-treated mESCs. ESC-derived cardiomyocyes (CM) treated with ouabain appeared to have more mature calcium handling. As demonstrated by confocal Ca 2+ imaging, cardiomyocytes isolated from ouabain-treated mESCs exhibited higher maximum upstroke velocity (P 2+ transient (P Conclusion: Ouabain induces cardiac differentiation and maturation of mESC-derived cardiomyocytes via activation of Erk1/2 and more mature SR for calcium handling. %U http://www.chinaphar.com/article/view/4866 %V 32 %N 1 %P 52-61 %@ 1745-7254