Regulation of Human Embryonic Stem Cell Proliferation and Differentiation by Wnt

在模式生物中的工作已经揭示，包括Wnt/β-连环蛋白通路在内的少数信号转导通路在整个发育过程中以及在成人的组织修复和干细胞稳态中发挥关键作用。有趣的是，Wnt/β-连环蛋白途径的组成在不同的细胞环境中不同，这取决于信号传导途径的独特修饰剂的表达或保守途径组分的不同亚型的表达。我们和其他人有证据（见初步研究），Wnt/β-连环蛋白信号在经历自我更新的多能人类胚胎干细胞（hESC）中受到抑制，并且在分化为早期和晚期中胚层细胞谱系期间信号是活跃的。 我们推测Wnt/β-catenin信号通路的环境依赖性调节剂在hESC的自我更新和分化中起关键作用。 该提议的最初目标是检验Wnt/β-连环蛋白信号传导的上下文依赖性调节剂在调节hESC的自我更新和分化中起关键作用的假设。我们相信，这一目标的追求将揭示Wnt/β-连环蛋白信号调节自我更新和细胞命运的规范在hESC中的详细机制。 我们的第二个目标是扩大我们对干细胞中信号转导通路的作用的研究，包括Hedgehog，Notch和TGF β通路，使用新型的多重荧光报告分子，使活细胞中的多个通路的同时监测。我们相信，同时可视化活细胞中多种信号通路的活性状态的技术的发展将在正常和患病组织中的信号通路的研究中具有许多用途。

Work in model organisms has revealed that a small number of signal transduction pathways, including the Wnt/b-catenin pathway, play key roles throughout development, as well as in tissue repair and stem cell homeostasis in adults. Interestingly, the composition of the Wnt/b-catenin pathway differs in distinct cellular contexts, depending on expression of unique modifiers of the signaling pathway, or expression of different isoforms of conserved pathway components. We and others have evidence (see Preliminary studies) that Wnt/b-catenin signaling is repressed in pluripotent human embryonic stem cells (hESCs) undergoing selfrenewal, and that signaling is active during differentiation into both early and later mesodermal cell lineages. We hypothesize that context-dependent modifiers of Wnt/b-catenin signaling play key roles in the self-renewal and differentiation of hESCs. The initial goal of this proposal is to test the hypothesis that context-dependent modulators of Wnt/b-catenin signaling play key roles in regulating self-renewal and differentiation in hESCs. We believe that pursuit of this goal will reveal detailed mechanisms by which Wnt/beta-catenin signaling regulates self-renewal and specification of cell fate in hESCs. Our second goal is to expand our investigation of the roles of signal transduction pathways in stem cells to include the Hedgehog, Notch, and TGFb pathways, using novel multiplexed fluorescent reporters to enable simultaneous monitoring of multiple pathways in live cells. We believe that the development of the technology to simultaneously visualize the state of activity of multiple signaling pathways in live cells will have numerous uses in studies of signaling pathways in normal and diseased tissues.