Molecular Drivers of Human Gliogenesis

项目摘要 中枢神经系统(CNS)的形成涉及到基本的细胞命运多样化- 神经元和神经胶质细胞的生成。神经元和神经胶质细胞的定时、连续出现对于 正确组织中枢神经系统的细胞结构和生理。为了支持这一点，神经源性的扰动- TO-胶质形成定时器在多种神经发育障碍中被证实。因此，一种理解 在控制这个细胞命运的机制中，决定是至关重要的。 尽管胶质生成开关是一种从苍蝇到人类保守的机制，但灵长类皮质经历了 显著的细胞和分子进化，使皮质表面增加了1000倍 与啮齿动物相比。这些进化变化包括一个独特的祖先种群的扩大 被称为外径向胶质细胞，以及分子、功能和形态特征的显著变化 星形胶质细胞。这些观察结果支持外径向神经胶质细胞是星形胶质细胞的细胞前体的假设。 人类星形胶质细胞，这一群体表现出人类特有的胶质形成驱动因素。这项建议旨在 解决关于人类神经胶质发生的两个关键基本问题：(1)人类祖细胞(S)在 发生了神经胶质细胞的转换，以及(2)驱动神经胶质细胞能力的内在机制是什么？ 在这项提议中，我们利用人的IPSC衍生的皮质有机体作为简化论模型系统来问 是什么驱使着人类神经胶质生成。有机模型系统是解决这个问题的理想方法，因为(A) 胶质形成在一个狭窄的时间窗口内持续且可重复地发生，以及(B)它是遗传的 易于处理并服从于精确的时间研究，这在其他平台上是不可能的。我们已经开发出 系统测试(目标1)人类天体形成的起源和分子驱动因素的两个目标，和(目标1) 2)人类特异的胶质原转录因子启动胶质形成的能力。我们提出了一套 将追踪单个细胞在整个胶质形成开关中的谱系轨迹的实验方法 并测试受损的胶质生成司机的机械冲击力。我们还提出了一套创新的 测试针对特定转录因子的候选转录因子的不同激活方案的实验 人类发展过程中的时间和空间约束模式。

Project Summary The formation of the central nervous system (CNS) involves a fundamental cell fate diversification—the generation of neurons and glia. The timed, sequential appearance of neurons followed by glia is critical for properly organizing CNS cytoarchitecture and physiology. In support of this, perturbations of the neurogenic- to-gliogenic timer have been demonstrated in multiple neurodevelopmental disorders. Thus, an understanding of the mechanisms that control this cell fate decision is of utmost importance. Although the gliogenic switch is a mechanism conserved from flies to humans, the primate cortex has undergone significant cellular and molecular evolution that has contributed to the >1000 fold increase in cortical surface area compared to rodents. These evolutionary changes include the expansion of a unique progenitor population called outer radial glia, along with significant changes in the molecular, functional, and morphological features of astrocytes. These observations support the hypothesis that outer radial glia are the cellular progenitors of human astrocytes and that this population exhibits human-specific gliogenic drivers. This proposal aims to address two key fundamental questions about human gliogenesis: (1) In which human progenitor cell(s) does the gliogenic switch occur, and (2) what are the intrinsic mechanisms that drive glial competence? In this proposal, we are utilizing human iPSC-derived cortical organoids as a reductionist model system to ask what drives human gliogenesis. The organoid model system is ideal for addressing this question because (a) gliogenesis occurs consistently and reproducibly within a narrow temporal window, and (b) it is genetically tractable and amenable to precise temporal studies that are not possible in other platofrms. We have developed two aims that systematically test (Aim 1) the origins and molecular drivers of human astrogenesis, and (Aim 2) the ability of human-specific pro-glial transcription factors to initiate gliogenesis. We propose a set of experimental approaches that will trace lineage trajectories of individual cells throughout the gliogenic swtich and also test the mechanistic impact of impaired gliogenic drivers. We also propose a set of innovative experiments to test distinct activation schemes of candidate transcription factors tailored to their specific temporal and spatial binding patterns during human development.