Genetic analysis of the Robo3+ glycinergic amacrine cell

项目摘要 视网膜是研究神经回路发育和功能的极佳模型。这个 视网膜包含五个主要的神经元类别，可细分为一百多个神经元 子类型。无长突细胞是五种神经细胞之一，仅占视网膜细胞的百分之一 种群，但约占这种亚型多样性的一半。只有少数几个AC亚型 进行了深入的研究，部分原因是缺乏工具来前瞻性地隔离和操纵个体群体。 因此，我们对视觉回路如何发挥作用的理解仍然不完整。例如，最近的工作 研究表明，方向选择回路是视网膜中研究最充分的回路之一，它包括甘氨酸能 来自未定义的AC子类型的输入。要充分了解ACS对视觉处理的贡献， 迫切需要研究更多的AC亚型及其定义特征。 在初步研究中，我鉴定了一个Robo3Creer小鼠品系，它在基因上标记了 先前未描述的甘氨酸能无长突细胞。根据它们的形态和层积模式，我 推测这些Robo3+无长突细胞(RAC)可能是为ON提供甘氨酸能抑制作用的细胞 方向选择回路中的星状突起无长突细胞。我将使用老鼠遗传学，共聚焦显微镜，在 用原位杂交、电子显微镜和电生理学来验证这一假说。在目标1中，我将定义 RAC的形态特征和种群水平的组织。在目标2中，我将确定RAC是否 在星爆无长突细胞上形成抑制性突触。在目标3中，我将确定Robo3是否扮演 在RAC开发和/或功能中的角色。这些目标将拓宽我们对单个细胞如何 在视网膜回路中，各部分共同发挥作用。

Project Summary The retina is an excellent model for studying the development and function of neural circuitry. The retina contains five major neuronal classes which can be subdivided into well over a hundred neuronal subtypes. Amacrine Cells (ACs), one of the five neuronal classes, comprise only one percent of the retinal cell population, but account for around half of this subtype diversity. Only a handful of AC subtypes have been studied in depth, in part due to a lack of tools to prospectively isolate and manipulate individual populations. Therefore, our understanding of how visual circuits function remains incomplete. For example, recent work shows that the direction selective circuit, one of the most well-studied circuits in the retina, includes glycinergic input from an undefined AC subtype. To fully understand how ACs contribute to visual processing it is imperative to study more AC subtypes and their defining features. In preliminary studies, I identified a Robo3CreER mouse line that genetically labels a population of previously undescribed glycinergic amacrine cells. Based on their morphology and stratification pattern, I hypothesize that these Robo3+ amacrine cells (RACs) may be the cells that supply glycinergic inhibition to ON starburst amacrine cells in the direction selective circuit. I will employ mouse genetics, confocal microscopy, in situ hybridization, electron microscopy, and electrophysiology to test this hypothesis. In Aim 1, I will define the morphological properties and population-level organization of RACs. In Aim 2, I will determine whether RACs form inhibitory synapses onto ON starburst amacrine cells. In Aim 3, I will determine whether Robo3 plays a role in RAC development and/or function. These aims will broaden our knowledge of how individual cellular components function together in retinal circuitry.