Proliferation, Specification & Brain Function

描述（由申请人提供）：本项目研究了发育中的内侧神经节隆起（MGE）中增殖和中间神经元命运决定的相互作用，并探讨了改变中间神经元亚群的功能后果。神经元的两大类}兴奋性和GABA能抑制性}实际上构成大脑皮层中的每一个神经回路。它们的形态、生化成分、电生理特性和突触连接可以区分各种各样的中间神经元亚型。尽管这些GABA能细胞对大脑功能很重要，但令人惊讶的是，人们对它们的产生如何在细胞或分子水平上进行调节知之甚少。 项目1（Ross PI）研究细胞周期成分在哺乳动物大脑模式和功能中的作用。他们发现，两种G1期活性细胞周期蛋白cD 1和cD 2在MGE中的不同祖细胞亚群中表达，其中cD 2的基因消融产生皮质PV+但不是SST+中间神经元的损失。实验探索cDI功能主要促进放射状胶质细胞（RGC）的不对称分裂的假设，其中一些产生SST+中间神经元。相比之下，cD 2可以促进主要产生PV+中间神经元的中间祖细胞（IPC）的对称分裂。项目2（安德森PI）研究了Notch、Wnt和Shh信号传导系统的相互作用，以调节由MGE产生的神经元的数量和亚型。他们发现Notch信号的调节增强了背侧MGE（dMGE）中的cD 2表达，并假设这将以SST+中间神经元为代价增加PV+输出。初步数据暗示Shh和Wnt信号之间的相互作用调节Notch活性以影响中间神经元的产生，这些关系将在项目3（Shi PI）中探索，该项目3（Shi PI）使用最先进的延时视频显微镜和免疫组织化学在子宫内注射逆转录病毒荧光蛋白，以检查调节MGE分裂的细胞内在和外在机制。这些iStudies与项目1和2中的细胞周期和信号研究紧密结合。 核心B（摩尔导向器）将确定选择性中间神经元缺陷的功能意义，这些缺陷涉及程序中生成的小鼠模型中的不同中间神经元亚型和解剖区域。寻找中间神经元亚群丢失对行为、脑结构和生理的后果。 人们广泛认识到，关键信号传导途径如Notch、Shh和Wnt与细胞周期调节因子如D-细胞周期蛋白广泛相互作用以调节神经元的产生和命运。然而，相互作用的复杂性，腹前脑衍生的神经元命运的多样性和基因操作在该地区的挑战构成了主要的障碍，在MGE的全面研究。该计划通过4位Pis的共同努力，使用尖端方法来阐明发育信号如何调节这些至关重要的神经元的命运和输出，从而解决了这种复杂性。

DESCRIPTION (provided by applicant): This Program examines the interaction of proliferation and interneuron fate determination in the developing medial ganglionic eminence (MGE), and probes functional consequences of altering interneuron subpopulations. Two broad classes of neurons}}}glutamatergic excitatory and GABAergic inhibitory}}} comprise virtually every neural circuit in cerebral cortex. Their morphology, biochemical constituents, electrophysiological properties and synaptic connections can distinguish a remarkable variety of interneuron subtypes. Despite the importance of these GABAergic cells to brain function, surprisingly little is known about how their production is regulated on a cellular or molecular level. Project 1 (Ross PI) studies the roles of cell cycle constituents in the patterning and function of mammalian brain. They found that two Gl-phase active cyclins, cDI and cD2, are expressed in different progenitor subsets in the MGE where genetic ablation of cD2 produces a loss of cortical PV+ but not SST+ interneurons. Experiments probe the hypothesis that cDI functions primarily to promote asymmetric divisions of radial glial cells (RGCs), some of which generate SST+ interneurons. In contrast, cD2 may promote the symmetric divisions of intermediate progenitor cells (IPCs) that will primarily generate PV+ interneurons Project 2 (Anderson PI) investigates the interacting roles of Notch, Wnt and Shh signaling systems to regulate the number and subtypes of neurons generated from the MGE. They have found that modulation of Notch signaling enhances cD2 expression in dorsal MGE (dMGE) and hypothesize that this will increase PV+ output at the expense of SST+ interneurons. Pilot data implicate interactions between Shh and Wnt signaling regulate Notch activity to impact interneuron production and these relationships will be explored Project 3 (Shi PI) uses in utero intraventricular injection of retroviral fluorescent proteins with state-of- the-art time-lapse videomicroscopy and immunohistochemistry to examine cell intrinsic and extrinsic mechanisms regulating divisions in the MGE. These istudies are heavily integrated with cell cycle and signaling investigations in Projects 1 and 2. Core B (Moore Dir.) will determine the functional significance of selective interneuron deficits that involve different interneuron subtypes and anatomical regions in mouse models generated within the Program. Consequences of interneuron subset loss on behavior, brain structure and physiology are sought. It is widely appreciated that key signaling pathways like Notch, Shh, and Wnt and cell cycle regulators like D-cyclins extensively interact to regulate neuronal generation and fate. However the complexity of the interactions, diversity of ventral forebrain-derived neuronal fates and challenges for gene manipulation in this region pose major impediments to comprehensive study in the MGE. This Program tackles this complexity through the combined efforts of 4 Pis using cutting edge approaches to the elucidation of how developmental signals regulate fate and output of these critically important neurons.