Control of Early hESC Fate Determination

本项目将明确人类胚胎干细胞（hESC）自我更新的机制， 以及如何做出早期差异化决策。 这些研究集中在PI 3 K在促进GSK 3-β活性中的作用，这是一个关键的调节点 用于阻断上皮向间充质转化（EMT）和向中内胚层分化。控制 在PI 3 K和GSK 3-β活性丧失后，中内胚层发育的机制尚不清楚。到 为了解决这个问题，Wnt和TGF-β家族成员在中内胚层特化中的各自作用将 被定义。理解这些问题不仅对hESC自我更新至关重要，而且对 理解支持早期细胞命运决定的基本机制，包括定形内胚层 和来自中内胚层前体的中胚层规格。 本项目的第一个目的是研究GSK 3-beta在EMT控制中的作用，以及它如何调节EMT的发生。 两种转录因子Snail 1和β-catenin的活性。这些转录因子 将定义对照EMT。 第二个目的是研究hESC自我更新所需的信号通路，具体来说， PI 3 K维持GSK 3-β活性并抑制EMT。 第三个目标，将建立早期细胞命运向中内胚层定型的确切条件，以及如何 Wnt和TGF-β协同作用以形成这种细胞类型。最后，我们将研究使用GSK 3-beta 抑制剂作为可促进hESC均匀分化的化合物。 了解hESC自我更新的机制是至关重要的，如果我们要利用他们的全部潜力， 发展模型，并作为可用于再生医学的细胞的治疗来源。我们 对hESC分化成不同谱系的理解还很不清楚。这项建议会 专注于细胞命运定型的非常早期阶段，这对于分化成两个关键谱系至关重要。 首先是中胚层，它可以产生血液、肌肉和骨骼。第二，定形内胚层， 上升到胰腺、肝脏、肺、肠和甲状腺。

This Project will define the mechanisms by which human embryonic stem cell (hESC) self-renewal is preserved and how early differentiation decisions are made. These studies focus on the role of PI3K in promoting GSK3-beta activity, a point of regulation that is critical for blocking an epithelial to mesenchymal transition (EMT) and differentiation towards mesendoderm. Control of mesendoderm development, following loss of PI3K and GSK3-beta activity, is not well understood. To address this issue, respective roles for Wnt and TGF-beta family members in mesendoderm specification will be defined. Understanding these issues is critical not only in relation to hESC self-renewal, but also for understanding the basic mechanisms underpinning early cell fate decisions, including definitive endoderm and mesoderm specification from a mesendoderm precursor. The first Aim of this Project will investigate the role of GSK3-beta in control of EMTs and how it regulates the activity of two transcription factors, Snail 1 and beta-catenin. Mechanisms by which these transcription factors control EMTs will be defined. The second Aim will investigate the signaling pathways required for hESC self-renewal and specifically, how PI3K maintains GSK3-beta activity and inhibits an EMT. The third Aim, will establish the exact conditions for early cell fate commitment to mesendoderm and how Wnt and TGF-beta synergize to pattern this cell type. Finally, we will investigate the use of GSK3-beta inhibitors as compounds that can promote uniform differentiation of hESCs. Understanding the mechanisms of hESC self-renewal is critical if we are to harness their full potential as a developmental model and as a therapeutic source of cells that can be used in regenerative medicine. Our understanding of hESC differentiation into different lineages is only poorly understood. This proposal will focus on a very early stage of cell fate commitment that is critical for differentiation into two key lineages. First, mesoderm which can give rise to blood, muscle and bone. Second, definitive endoderm which gives rise to pancreas, liver, lung, intestine and thyroid.