Administrative Supplement to NEI - EY030138

项目总结 在眼睛里，复杂的视网膜回路连接在一起，进行精确的神经计算。多种多样但精准的 中间神经元和视网膜神经节细胞之间的联系是脑电活动的结构基础。 不同的视觉特征。这些并行电路被精确地连接在一起，因为缺陷可能会导致几只眼睛 疾病和神经紊乱。为了研究不同神经元类型背后的机制 精确地整合到不同的平行视网膜回路中，我们开发了允许靶向基因的方法 传送方向选择信号的独特的开关方向选择电路的接入是理想的 模型系统。我们之前的研究使我们能够研究II型钙粘附素(CDHS)在脑内的作用 以单独的蛋白质或组合的形式组装这个环路。我们发现了两个CDH，CDH9和CDH8， 指示平行的ON和OFF双极细胞输入到ON与OFF亚胺的ON与OFF亚胺-方向选择性 电路，因此可以精确地隔离开和关通道。然而，分子机制 这种集合的基础仍然难以捉摸。研究这种差异背后的分子机制 CDH9和CDH8的功能，我们将进行一系列的解剖学和功能分析。我们将确定 钙粘附素分子的特定部分，细胞外与细胞内结构域，负责 它们的不同功能，以及它们在双极细胞之间形成突触的具体时间 和神经节细胞。我们还发现，来自双极神经元的CDH9异嗜性地识别这两者- 突触后腹侧指向开关方向选择性神经节细胞相关CDHs、CDH6和CDH10的表达 (OoDSGCs)和星爆型无长突细胞(SACs)。我们将利用这个已建立的遗传系统来揭示 组合CDH共同作用，将平行的方向选择电路连接在一起。我们将对基因和 从功能上讲，CDH6-9-10单一、双重和三重组合如何塑造腹侧-oODSGC相互作用 带着囊。为了进一步扩大我们对神经元模式中的组合钙粘素密码的理解，我们 将测试CDH11的作用，它是通过分子鉴定为鼻尖ooDSGC富集区的基因 侧写。因此，我们将产生新的分子和基因靶向方法来检查 CDH11及其密切相关的CDH8在鼻尖方向选择回路的布线中。此外，我们 建立了宫内注射系统，将个体II型CDHS异位引入腹侧- OoDSGCs或鼻腔ooDSGCs，以确定组合CDH在调节DS-电路图案中的作用。总而言之， 我们的研究试图揭示CDH组合如何控制平行但不同的DS电路的形成。 对II型CDH功能的全面研究将是一个长期存在的问题的重大进展 哺乳动物的神经发育。这些研究将是在理解多个 基因的相互作用决定了复杂神经回路的连接方式。已确定的机制将对 与中枢神经系统的选择性电路连接有关。

PROJECT SUMMARY In the eye, complex retinal circuits are wired together for precise neural computation. The diverse but precise wiring between interneurons and retinal ganglion cells serve as the structural basis for circuit processing of different visual features. These parallel circuits are wired up precisely, as defects may lead to several eye diseases and neurological disorders. To investigate the mechanisms behind how diverse neuronal types precisely integrate into distinct parallel retinal circuits, we developed methods that allow for targeted genetic access of the unique On-Off direction-selective circuit, which conveys direction-selectivity signals, as the ideal model system. Our previous studies now position us to examine the role of Type II Cadherins (Cdhs) in assembling this circuit as individual proteins or in combinations. We showed that two Cdhs, Cdh9 and Cdh8, instruct parallel ON and OFF bipolar cell input to ON vs. OFF sublaminae of the ON-OFF direction-selective circuit, thus allowing precise segregation of ON and OFF channels. However, the molecular mechanisms underlying this assembly remain elusive. To investigate the molecular mechanisms underlying the differential functions of Cdh9 vs. Cdh8, we will perform a series of anatomical and functional analyses. We will identify the specific portion of the cadherin molecule, extracellular versus intracellular domains, that are responsible for their distinct functions, as well as the specific timing of their actions in forming synapses between bipolar cells and ganglion cells. We also found that Cdh9 from bipolar neurons heterophilically recognizes the two closely- related Cdhs, Cdh6 and Cdh10, from postsynaptic Ventral-pointing ON-OFF direction-selective ganglion cells (ooDSGCs) and starburst amacrine cells (SACs). We will use this established genetic system to reveal how combinatorial Cdhs act together to wire up parallel direction-selective circuits. We will examine genetically and functionally how Cdh6-9-10 single, double, and triple combinations pattern the Ventral-ooDSGC interaction with SACs. To further expand our understanding of the combinatorial cadherin code in neuronal patterning, we will test the role of Cdh11, which is identified as a Nasal-pointing ooDSGC enriched gene through molecular profiling. Thus, we will generate new molecularly and genetically targeted methods to examine the roles of Cdh11 and its closely related Cdh8 in the wiring of Nasal-pointing direction-selective circuits. Furthermore, we established an in utero injection system to ectopically introduce individual Type II Cdhs onto Ventral- ooDSGCs or Nasal-ooDSGCs to pinpoint combinatorial Cdhs in regulating DS-circuit patterning. Collectively, our studies seek to reveal how Cdh combinations control the formation of parallel but distinct DS circuits. Comprehensive studies on Type II Cdh function would be a major advance for a long-standing question in mammalian neural development. These studies will be a major step forward in understanding how multiple genes interact to specify the wiring of complex neural circuits. The identified mechanisms will have significant relevance to selective circuit wiring throughout the central nervous system.