Molecular mechanisms of cardiomyocyte differentiation and their therapeutic implications

1)IGFBP-4促进心肌细胞分化我们先前分离到IGFBP-4是一种从基质细胞系OP-9分泌的心源性生长因子。在这项研究中，我们证明了IGFBP-4通过抑制典型的Wnt信号而促进心肌细胞分化。我们还在ES细胞和非洲爪哇胚胎中敲除了IGFBP-4，以探讨内源性IGFBP-4在心肌细胞分化中的作用。IGFBP-4基因敲除可导致ES细胞中心肌细胞分化的丧失和非洲爪哇胚胎心脏形成的丧失，表明IGFBP-4在体外和体内心肌发生中都是必需的。2)心脏生长因子的下游信号。本研究探讨了Wnt信号在ES细胞分化中的作用。在ES细胞分化的早期，Wnt促进心肌细胞的分化，而在晚期则减弱，提示规范的Wnt信号对CAR-…的影响更多的肌发生是以发育阶段特有的方式分两个阶段进行的。我们还建立了一个ES细胞系，可以同时观察心肌细胞的分化和Wnt信号的激活，这将是进一步剖析Wnt信号在心肌发生中作用的有用工具。3)α蛋白激酶家族在体内心脏发育中的作用ALPK3属于α蛋白激酶家族，当在胚胎癌细胞P19CL6中过表达时促进心肌细胞的分化。为了探讨α蛋白激酶家族在体内心脏发育中的作用，建立了ALPK3基因敲除(KO)小鼠。ALKP3KO小鼠出生正常，无明显表型。为了验证α-激酶家族不同成员之间是否存在遗传冗余，我们检测了心脏α-激酶(HAK)KO小鼠和ALPK3/HAK双KO小鼠的表型。然而，这些小鼠也没有表现出明显的表型，这表明这些激酶对体内心脏发育不是必不可少的。较少

1) Promotion of cardiomyocyte differentiation by IGFBP-4 We previously isolated IGFBP-4 as a cardiogenic growth factor secreted from a stromal cell line OP-9. In this study we have demonstrated that IGFBP-4 promotes cardiomyocyte differentiation by inhibiting canonical Wnt signaling. We also knocked down IGFBP-4 in ES cells and in Xenopus embryos to explore the role of endogenous IGFBP-4 on cardiomyocyte differentiation. Knockdown of IGFBP-4 resulted in a loss of cardiomyocyte differentiation in ES cells and loss of heart formation in Xenopus embryos, indicating that IGFBP-4 is essential for both in vitro and in vivo cardiomyogenesis.2) Downstream signaling of cardiogenic growth factors In this study we explored the role of canonical Wnt signaling in cardiomyocyte differentiation of ES cells. In the early phase of ES cell differentiation, Wnt promoted cardiomyocyte differentiation, whereas in the late phase Wnt attenuated it, suggesting that the effect of canonical Wnt signaling on car … More diomyogenesis is biphasic in a developmental stage-specific manner. We also established an ES cell line that enables simultaneous visualization of cardiomyocyte differentiation and activation of Wnt signaling, which will be a useful tool for further dissection of the role of Wnt signaling on cardiomyogenesis.3) Role of α-kinase family of protein kinases in heart development in vivo ALPK3 belongs to α-kinase family of protein kinases and promotes cardiomyocyte differentiation when overexpressed in embryonal carcinoma cell line P19CL6. To explore the role of α-kinase family of protein kinases in heart development in vivo, ALPK3 knockout (KO) mice were generated. ALKP3 KO mice were born normally and exhibited no obvious phenotype. To test whether there are genetic redundancies among different members of the α-kinase family, the phenotype of heart α-kinase (HAK) KO mice and ALPK3/HAK double KO mice were examined. However, these mice also exhibited no obvious phenotype, suggesting that these kinases are not essential for heart development in vivo. Less