Molecular Drivers of Human Gliogenesis

项目摘要 中枢神经系统（CNS）的形成涉及基本的细胞命运多样化--细胞分化。 神经元和神经胶质的生成。神经元和神经胶质细胞的定时、顺序出现对于 正确组织CNS细胞结构和生理学。为了支持这一点，神经原性的干扰- 在多种神经发育障碍中已经证实了胶质细胞生成计时器。因此， 控制这种细胞命运决定的机制至关重要。 虽然胶质细胞生成开关是一种从苍蝇到人类的保守机制，但灵长类动物的大脑皮层经历了 显著的细胞和分子进化，导致皮质表面增加>1000倍 与啮齿动物相比。这些进化变化包括一个独特的祖先群体的扩张 称为外放射状神经胶质细胞，沿着具有分子、功能和形态特征的显著变化 星形胶质细胞。这些观察结果支持了这样的假设，即外放射状胶质细胞是神经胶质细胞的祖细胞。 人星形胶质细胞，并且该群体表现出人特异性胶质原驱动。这项建议旨在 解决了关于人类胶质细胞生成的两个关键的基本问题：（1）人类祖细胞在哪些细胞中 胶质细胞发生开关的发生，以及（2）驱动胶质细胞能力的内在机制是什么？ 在这个提议中，我们利用人类iPSC衍生的皮质类器官作为简化模型系统， 是什么驱动了人类胶质细胞的生成类器官模型系统是解决这个问题的理想选择，因为（a） 胶质细胞生成在狭窄的时间窗内持续且可再现地发生，并且（B）它是遗传性的 易于处理和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 两个目标，系统地测试（目标1）人类天体形成的起源和分子驱动力，和（目标 2)人类特异性前神经胶质转录因子启动神经胶质形成的能力。我们提出了一套 实验方法将追踪整个胶质细胞形成过程中单个细胞的谱系轨迹， 并测试受损的胶质原驱动程序的机械影响。我们还提出了一套创新的 实验以测试针对其特定的候选转录因子的不同激活方案， 人类发展过程中的时空结合模式。

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.