Progenitor Regulation Underlying Cortical Interneuron Specification

皮层中间神经元特化的祖细胞调节 抑制性γ-氨基丁酸能中间神经元调节复杂皮层回路的运作。大多数皮层中间神经元 起源于内侧神经节隆起（MGE）祖细胞，其表达转录因子NKX2.1， 腹侧MGE和背侧MGE中的NKX6.2。虽然兴奋性主神经元的产生一直是 广泛研究，了解中间神经元的发生，特别是MGE的行为和调节 祖先，仍然非常有限。拟议的项目解决了这一突出的知识差距。 虽然成熟的皮质中间神经元是高度多样化的，但采用神经胶质或神经胶质细胞的主要决定是： 生长抑素（SOM+）或小清蛋白（PV+）表达神经元命运的细胞在MGE中作为祖细胞。 基于来自Shi和Ross实验室的强有力的初步数据，我们假设一个紧密的空间和 MGE祖细胞的行为和基因表达特性的时间调节对于适当的免疫调节是必要的。 产生的interneurons注定皮层。该项目包括两个主要目标： 目的1探讨祖细胞极性决定子、分配缺陷型和非极性决定子之间的功能相互作用 3（PARD 3）和G1期活性细胞周期蛋白，细胞周期蛋白D1（cD 1）与D2（cD 2），在调节MGE细胞 分裂，测试2个假设：1a. MGE祖细胞分裂模式和动力学在空间和时间上是相互关联的。 调节以产生适当的PV+和SOM+中间神经元数量。逆转录病毒和MADM技术， 计算模型将用于确定MGE的空间（背侧与腹侧）和时间动态 放射状胶质祖细胞（RGP）和中间祖细胞（IPC）分裂模式和中间神经元输出。1b. PARD 3和cD 1与cD 2之间的差异相互作用协调MGE祖细胞分裂模式， 动态调节适当的PV+与SOM+的命运。研究追求PARD 3和 cD 2与cD 1在支配MGE RGP和IPC的分裂模式、动力学和皮质中间神经元输出中的对比。 目的2探索调控MGE RGPs时空行为的核心分子程序 使用10 X基于基因组学的野生型、cD 2-/-、cD 1-/-、Pard 3 cKO和 Pard 3cKO; cD 2-/-双突变体。假设：MGE输出取决于定义cD 1的基因表达， CD 2依赖性祖细胞库，它们的分裂模式和动力学。表达网络将通过 组织学和分子操作，包括关键驱动候选人的CRISPR/Cas9基因组编辑 的MGE祖细胞特化，并且其表达在cD 1或cD 2和Pard 3突变MGE中改变。 该项目将解决关于皮层中间神经元发生的大量知识缺口， 为MGE祖细胞的空间和时间调控提供了基本框架，阐明了其 分裂模式和动力学，它们的中间神经元输出，以及协调MGE的底层核心程序 祖细胞分裂调节和中间神经元特化。

PROGENITOR REGULATION UNDERLYING CORTICAL INTERNEURON SPECIFICATION Inhibitory GABAergic interneurons modulate complex cortical circuit operation. Most cortical interneurons originate from medial ganglionic eminence (MGE) progenitors that express the transcription factors, NKX2.1 in the ventral MGE and NKX6.2 in the dorsal MGE. While excitatory principal neuron production has been extensively studied, understanding of interneuron genesis, particularly the behavior and regulation of MGE progenitors, remains very limited. The proposed project addresses this outstanding knowledge gap. Although mature cortical interneurons are highly diverse, primary decisions to adopt a glial or somatostatin (SOM+) or parvalbumin (PV+) expressing neuronal fate are made as progenitors in the MGE. Based on strong preliminary data from the Shi and Ross laboratories, we hypothesize that a tight spatial and temporal regulation of the behavior and gene expression properties of MGE progenitors is essential for proper production of interneurons destined for the cortex. The project encompasses two major goals: Aim 1 probes the functional interactions between progenitor cell polarity determinant, partition defective 3 (PARD3), and G1-phase active cell cycle proteins, cyclins D1 (cD1) vs. D2 (cD2), in regulating MGE cell division, testing 2 hypotheses: 1a. MGE progenitor division modes and dynamics are spatially and temporally regulated to generate proper PV+ and SOM+ interneuron numbers. Retroviral and MADM technologies with computational modeling will be used to determine spatial (dorsal vs. ventral) and temporal dynamics of MGE radial glial progenitor (RGP) and intermediate progenitor cell (IPC) division modes and interneuron output. 1b. Differential interactions between PARD3 and cD1 vs. cD2 coordinate MGE progenitor division mode and dynamics to regulate proper PV+ vs. SOM+ fates. Studies pursue differential interactions between PARD3 and cD2 vs. cD1 in governing division mode, dynamics, and cortical interneuron output of MGE RGPs and IPCs. Aim 2 explores the core molecular program regulating the spatial and temporal behavior of MGE RGPs and IPCs using 10X Genomics-based single cell RNA sequencing of wildtype, cD2–/–, cD1–/–, Pard3 cKO and Pard3cKO;cD2–/– double mutants. Hypothesis: MGE output depends on gene expression defining cD1 and cD2 dependent progenitor pools, their division mode and dynamics. Expression networks will be validated by histological and molecular manipulation, including CRISPR/Cas9 genome editing of candidates for key drivers of MGE progenitor specification and whose expression is altered in cD1 or cD2 and Pard3 mutant MGE. The project will address a substantial knowledge gap regarding cortical interneuron genesis and provides a fundamental framework for the spatial and temporal regulation of MGE progenitors, elucidating their division mode and dynamics, their interneuron output, and the underlying core program coordinating MGE progenitor division regulation and interneuron specification.