Combinatorial roles of cadherins in retinal circuit assembly.

钙粘蛋白在视网膜电路组装中的组合作用。

• 批准号: 8962693
• 负责人: JOSHUA R SANES
• 金额: $ 41.61万
• 依托单位: HARVARD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-12-01 至 2020-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8962693
• 关键词: Address; Affect; Brain; Brain Diseases; Cadherins; Cells; Color; Complex; Cytoplasmic Tail; Defect; Dendrites; Development; Electrophysiology (science); Ensure; Exons; Extracellular Domain; Family; Gene Family; Genes; Genetic; Genomics; Individual; Inner Plexiform Layer; Interneurons; Lateral; Learning; Mediating; Mental disorders; Methods; Modeling; Molecular; Molecular Genetics; Motion; Multigene Family; Mus; Mutate; Neuraxis; Neurons; Pattern; Play; Positioning Attribute; Process; Proteins; RNA Splicing; Reagent; Rest; Retina; Retinal; Retinal Ganglion Cells; Role; Specificity; Stereotyping; Structure; Surface; Synapses; System; Testing; Time; Transgenic Organisms; Transmembrane Domain; Visual; Visual Fields; Work; cell type; combinatorial; fascinate; gain of function; genome editing; in vivo; information processing; member; mouse genome; mutant; nervous system disorder; neural circuit; public health relevance; selective expression; starburst amacrine cell

 DESCRIPTION (provided by applicant): Orderly and specific connections among neurons of multiple types underlie the function of neural circuits. Our work has used mouse retina as a model to identiy molecules and mechanisms that underlie this specificity. The retina is not only important and fascinating in its own right, but is also a particularly accessible portion of the central nervous system. Moreover, we and others have generated a set of transgenic lines that allow specific retinal cell types to be marked and manipulated. We focus on the inner plexiform layer (IPL) in which dozens of types of interneurons (amacrine and bipolar cells) form stereotyped patterns of connectivity with ~30 types of retinal ganglion cells (RGCs), endowing each of them with sensitivity to visual features such as motion in a particular direction or color contrast. Wiring up these largely hard-wired circuits seems likely to require many cell type-specific molecules. Over the past several years he have identified several candidates, and tested them in vivo using loss- and gain-of-function strategies. During the past project period, we found two roles for members of the cadherin superfamily of recognition molecules in assembly of the IPL. First, a pair of classical cadherins (Cdh8 and Cdh9) play instructive roles in directing axonal arbors of two bipolar cell types (BC2, BC5) to appropriate sublaminae within the IPL. Second, a group of clustered gamma protocadherins (Pcdhg's) are required for dendritic patterning of starburst amacrine cells (SACs) in the lateral plane. Fortuitously, BC2, BC5 and SACs are all components of a direction-selective circuit that also includes ON-OFF direction-selective RGCs, which send information about motion in four cardinal directions to the rest of the brain. These results provide us with the opportunity to address a long- standing issue: how do members of multigene families work together in combinations to pattern neural circuits. Using new genome editing methods, we have generated double and triple mutants that lack (a) both Cdh8 and its closest relative Cdh11, (b) Cdh9 and its closest relatives, Cdh6 and Cdh10, and (c) Pcdhgs and their closest relatives, the alpha-Pcdhs. Importantly all of these genes are expressed by cells of the direction-selective circuit. Our aims now are to analyze mutants in which genes of the cadherin superfamily have been mutated singly and in combination. We will use molecular, histological and electrophysiological methods to analyze the consequences of these perturbations on the structure and function of the direction-selective circuit. Together, these studies will allow us to take a first step toward confronting the disturbing reality that analysis of single genes is insufficient to understand the assembly of complex neural circuits.

 描述（由申请人提供）：多种类型的神经元之间的有序和特定连接构成神经回路功能的基础。我们的工作使用小鼠视网膜作为模型来识别这种特异性的分子和机制。视网膜不仅本身重要和迷人，而且是中枢神经系统的一个特别容易接近的部分。此外，我们和其他人已经产生了一组转基因系，允许特定的视网膜细胞类型被标记和操纵。我们专注于内丛状层（IPL），其中数十种类型的中间神经元（无长突细胞和双极细胞）与约30种类型的视网膜神经节细胞（RGC）形成刻板的连接模式，赋予它们对视觉特征（如特定方向的运动或颜色对比度）的敏感性。连接这些基本上是硬连线的电路似乎需要许多细胞类型特异性分子。在过去的几年里，他已经确定了几个候选人，并使用功能丧失和获得策略在体内对其进行了测试。在过去的项目期间，我们发现了两个角色的钙粘蛋白超家族成员的识别分子组装的强脉冲光。首先，一对经典的钙粘蛋白（Cdh 8和Cdh 9）在细胞凋亡中起指导作用。 将两种双极细胞类型（BC 2，BC 5）的轴突乔木定向到IPL内的适当亚板层。第二，一组成簇的γ原钙粘蛋白（Pcdhg）是必需的星形无长突细胞（SAC）在侧平面的树突图案。幸运的是，BC 2，BC 5和SAC都是方向选择回路的组成部分，该回路还包括ON-OFF方向选择RGC，它将四个主要方向的运动信息发送到大脑的其他部分。这些结果为我们提供了解决一个长期存在的问题的机会：多基因家族的成员如何组合在一起工作来形成神经回路。使用新的基因组编辑方法，我们已经产生了双重和三重突变体，它们缺乏（a）Cdh 8及其最近的亲属Cdh 11，（B）Cdh 9及其最近的亲属Cdh 6和Cdh 10，以及（c）Pcdhgs及其最近的亲属alpha-Pcdhs。重要的是，所有这些基因都由方向选择回路的细胞表达。我们现在的目标是分析钙粘蛋白超家族的基因单独突变和组合突变的突变体。我们将使用分子，组织学和电生理学的方法来分析这些扰动的结构和功能的方向选择电路的后果。总之，这些研究将使我们朝着面对令人不安的现实迈出第一步，即对单个基因的分析不足以理解复杂神经回路的组装。