心脏起搏细胞是起始并维持正常心跳的重要细胞，其病变会引起心律失常，甚至猝死。目前最有效的治疗手段是植入电子起搏器，但因其固有缺点，人类多能干细胞来源的生物起搏器亟需发展。目前虽有干细胞来源的起搏细胞成功分化的报导，但其效率和纯度仍有待提高，限制了生物起搏器面向应用的发展。我们之前的研究发现典型Wnt通路促进起搏细胞的分化，但其精确调控机制尚不清楚。为进一步探索起搏细胞发育分化的精确调控的新机制，我们初步研究发现，抑制FGF通路可异位激活典型Wnt通路，并增加起搏细胞的分化数量。据此我们推测FGF通路通过时空特异地抑制典型Wnt通路从而精确调控起搏细胞的分化。本项目将在体内和体外系统中深入研究FGF和典型Wnt通路反向协同精确调控起搏细胞分化的分子机制。预期研究结果不仅能首次揭示不同信号通路协同精确调控起搏细胞分化的新机制，而且能为提高其体外分化效率提供线索，促进生物起搏器研究的进一步发展。

Pacemaker cardiomyocytes are essential for the initiation and maintenance of proper heart rhythm. Dysfunction of these cells can lead to severe cardiac arrhythmias and even sudden cardiac death. Implantation of an electronic pacemaker is currently the most effective treatment, but these electronic devices have a number of drawbacks. Methods for generating human pluripotent stem cell (hPSC) derived pacemaker cardiomyocytes as an alternative biological pacemaker therapy are in need. Although some strategies have been developed to create hPSC derived pacemaker cardiomyocytes, the differentiation efficiency and purity is limited, which hinders the translational applications. Even though our previous findings demonstrate that canonical Wnt5b signaling promotes pacemaker cardiomyocyte differentiation, the precise regulation mechanism for pacemaker cardiomyocyte differentiation remains elusive. In order to further investigate this, our preliminary data indicates that inhibition of FGF signaling can lead to ectopic activation of canonical Wnt signaling, and further increase pacemaker cardiomyocytes. Thus we hypothesize that FGF signaling spatiotemporally inhibits canonical Wnt5b signaling to precisely control pacemaker cardiomyocyte differentiation. In this proposal, we will investigate whether and how FGF and canonical Wnt signaling coordinate to precisely control pacemaker cardiomyocyte differentiation both in vivo and in vitro. The expected results will not only reveal a novel mechanism of how different signaling pathways coordinate and precisely control pacemaker cardiomyocyte differentiation, but also provide potential strategies for the increase of in vitro pacemaker cardiomyocyte differentiation efficiency and purity, therefore further promoting the development of biological pacemaker therapy.