Studying the Molecular Regulation of MGE Projection Neuron Identity by St18

项目摘要：内侧神经节隆起(MGE)是位于腹侧的神经前体区域 端脑。它因其产生皮质中间神经元而被广泛研究，皮质中间神经元是一个广泛分布的局部亲神经元群。 调节大脑皮层节律性的神经元。MGE还产生留在腹侧的投射神经元 前脑，排列成离散的核团，向远端点到点地投射。中间神经元和投射神经元同一性代表 两个根本不同的种群，具有不同的功能。MGE如何在IN的生产和生产之间进行划分 然而，PN还不被理解。 我们已经确定了一种转录因子St18，它似乎调控着这一基本的描述。我们之前 描述了一种利用候选因子的诱导表达来研究MGE发育的模型系统。当St18被介绍的时候- 在这个系统中，细胞很大程度上采用了投射神经元的身份。此外，当这些细胞被移植到 子宫内，它们留在腹侧前脑，采用让人想起苍白球部分的长程轴突投射。 外部(GPE)。此外，在我们对St18条件性功能丧失突变小鼠的初步分析中，我们观察到一种特殊的- GPE神经元的明显丢失，而所有其他MGE谱系似乎幸免于难。 在这项提案中，我们将：目标1)确定St18诱导的表达是否足以指导MGE祖细胞 向投射神经元鉴定(技术：胚胎干细胞定向分化、神经元培养、体外迁移试验、 UBM移植，RNA-seq)。目的2)通过对MGE投射神经元命运的分析，验证St18是否是MGE投射神经元命运所必需的 St18条件性功能丧失小鼠(技术：小鼠遗传学，轴突投射的病毒和染料追踪，scRNA- SEQ)。目的3)在MGE祖细胞分化过程中操纵St18，以探测其作用的时间窗口，并测试其如何 调节基因表达以引导投射神经元的识别(技术：胚胎干细胞定向分化，体外更多 生理和迁移分析，芯片序列)。重要的是，在我们的研究过程中，我们将进行多层次的表达 和芯片序列分析，以揭示在st18调控下的基因网络和细胞通路，这些共同 管理投射神经元特性的各个方面：神经元迁移、极性、突起形态发生。总而言之，我们是 独一无二地定位于解决MGE前体如何调节MGE中投射神经元与神经元间的身份 血统。通过这些努力，我们的目标是更广泛地了解投射和神经元间同一性是如何分配的 贯穿整个神经系统。

PROJECT SUMMARY: The medial ganglionic eminence (MGE) is a neural progenitor domain located in the ventral telencephalon. It is well-studied for its production of cortical interneurons, a broadly distributed population of locally-pro- jecting neurons that regulate cortical rhythmicity. The MGE also produces projection neurons that remain in the ventral forebrain, arranged in discrete nuclei that project distally point-to-point. Interneuron and projection neuron identity represent two fundamentally-distinct populations, with distinct functions. How the MGE delineates between the production of IN and PN, however, is not understood. We have identified a transcription factor, St18 that appears to regulate this fundamental delineation. We previously described a model system to study MGE development using induced expression of candidate factors. When St18 was intro- duced in this system, the cells largely adopted a projection neuron identity. Further, when these cells were transplanted in utero, they remained in the ventral forebrain and adopted long-range axonal projections reminiscent of globus pallidus pars externa (GPe). Moreover, in our initial analysis of the St18 conditional loss-of-function mutant mouse, we observed a spe- cific loss of GPe neurons, while all other MGE lineages appear spared. In this proposal, we will; Aim 1) Determine whether St18 induced expression is sufficient to direct MGE progenitors towards projection neuron identity (Techniques: ESC directed differentiation, neuronal culture, in vitro migration assays, UBM transplantation, RNA-seq). Aim 2) Test whether St18 is necessary for MGE projection neuron fate by analysis of St18 conditional loss-of-function mouse (Techniques: mouse genetics, viral and dye tracing of axon projections, scRNA- seq). Aim 3) Manipulate St18 during MGE progenitor differentiation to probe the time window of its action and test how it regulates gene expression in directing projection neuron identity (Techniques: ESC directed differentiation, in vitro mor- phology and migration assays, ChIP-seq). Importantly, in the course of our study, we will perform a multi-level expression and ChIP-seq analysis to uncover the gene networks and cellular pathways under the regulation of St18 that collectively govern aspects of projection neuron identity: neuronal migration, polarity, process morphogenesis. In summary, we are uniquely positioned to address how MGE progenitors regulate projection neuron versus interneuron identity in the MGE lineage. Through these efforts, we aim to inform more broadly as to how projection and interneuron identity is assigned throughout the nervous system.