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（由适用提供）：多种类型之间的有序和特定连接是神经元功能的基础。我们的工作使用小鼠视网膜作为模型来识别该特异性构成的分子和机制。视网膜本身不仅重要且引人入胜，而且还是中枢神经系统中特别接近的部分。此外，我们和其他人生成了一组转基因线，这些线允许标记和操纵特定的视网膜细胞类型。我们专注于内部丛状层（IPL），其中数十种类型的中间神经元（无氨基氨基和双极细胞）形成了与〜30种类型的视网膜神经节细胞（RGC）形成的刻板印象，使每一种类型的视网膜神经节细胞（RGC）赋予它们对视觉特征（例如在特定方向或颜色形成鲜明对比的运动）上的敏感性。将这些在很大程度上的硬线电路接线似乎是许多类型特异性分子。在过去的几年中，他确定了几个候选人，并使用功能障碍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IPL组装中识别分子的cadherin超家族成员的两个角色。首先，一对古典钙粘蛋白（CDH8和CDH9）在 将两种双极细胞类型（BC2，BC5）的轴突轴向引导到IPL内的适当sublaminae。其次，一组簇的伽马方案（PCDHG）是横向平面中的星爆肿瘤细胞（SAC）的树突状模式所必需的。幸运的是，BC2，BC5和SAC是方向选择性电路的所有组件，还包括开关方向选择性RGC，它们以四个基本方向向大脑的其余部分发送有关运动的信息。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共同努力，结合模式中性电路。使用新的基因组编辑方法，我们产生了缺乏CDH8及其最接近的亲属，（b）CDH9及其最接近的亲戚CDH6和CDH10的双重和三重突变体，以及（c）PCDHGS及其最接近的亲戚Alpha-PCDHS。重要的是，所有这些基因均由方向选择性电路的细胞表达。我们现在的目标是分析突变体，其中钙粘蛋白超家族的基因已被单独突变而结合。我们将使用分子，组织学和电生理方法来分析这些扰动对方向选择性电路的结构和功能的后果。这些研究将共同​​使我们迈出第一步，即面对令人不安的现实，即单个基因的分析不足以理解复杂的神经回路的组装。