Mechanisms Underlying Type II Cadherin Guided Assembly of Retinal Circuits

II 型钙粘蛋白引导视网膜电路组装的潜在机制

• 批准号: 9886125
• 负责人: Xin Duan
• 金额: $ 40.25万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-01-01 至 2024-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9886125
• 关键词: Address; Adopted; Anatomy; Atlases; Axon; Biological Assay; Biological Models; Bipolar Neuron; Brain; Brain region; Cadherins; Cell Adhesion Molecules; Cell Communication; Cells; Chimeric Proteins; Clustered Regularly Interspaced Short Palindromic Repeats; Code; Complex; Defect; Detection; Development; Disease; Ensure; Etiology; Eye; Eye diseases; Family; Genes; Genetic; Genetic Techniques; Goals; Individual; Injections; Interneurons; Knowledge; Lead; Location; Logic; Mediating; Methods; Molecular; Molecular Profiling; Nervous system structure; Neuraxis; Neurites; Neurons; Nose; Pattern; Physiological; Positioning Attribute; Process; Proteins; Retina; Retinal Ganglion Cells; Role; Series; Signal Transduction; Specific qualifier value; Specificity; Structure; Study models; Synapses; System; Testing; To specify; Translating; Vision; Visual; axon guidance; base; combinatorial; differential expression; experimental study; extracellular; gain of function; ganglion cell; genetic approach; in utero; in vivo; innovation; insight; mutant; nervous system disorder; neural circuit; neurodevelopment; neuronal patterning; novel; postsynaptic; relating to nervous system; retinal neuron; segregation; starburst amacrine cell; synaptogenesis; tool; visual information

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.

在眼睛中，复杂的视网膜电路连接在一起以进行精确的神经计算。多样但精确 中间神经元和视网膜神经节细胞之间的布线是电路处理的结构基础 不同的视觉特征。这些并联电路的接线非常精确，因为缺陷可能会导致几只眼睛 疾病和神经系统疾病。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遗传的方法 访问独特的开关方向选择电路，该电路传送方向选择性信号，作为理想的 模型系统。我们之前的研究现在使我们能够检验 II 型钙粘蛋白 (Cdhs) 在 将此电路组装为单个蛋白质或组合。我们展示了两个 Cdh，Cdh9 和 Cdh8， 指示并行 ON 和 OFF 双极电池输入到 ON-OFF 方向选择性的 ON 与 OFF 子层 电路，从而允许精确隔离开和关通道。然而，分子机制 这一大会的基础仍然难以捉摸。研究差异背后的分子机制 为了了解 Cdh9 与 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 钙粘蛋白分子的特定部分，细胞外结构域与细胞内结构域，负责 它们独特的功能，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 异嗜性地识别来自突触后腹侧指向 ON-OFF 方向选择性神经节细胞的两个密切相关的 Cdh，Cdh6 和 Cdh10 （ooDSGC）和星爆无长突细胞（SAC）。我们将利用这个已建立的遗传系统来揭示如何 组合 Cdh 共同作用以连接并行方向选择电路。我们将进行基因检查并 在功能上，Cdh6-9-10 单、双和三组合如何模式化 Ventral-ooDSGC 相互作用 与 SAC。为了进一步扩大我们对神经元模式中组合钙粘蛋白代码的理解，我们 将测试 Cdh11 的作用，该基因通过分子生物学鉴定为 Nasal-pointing ooDSGC 富集基因 分析。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 在鼻指向方向选择电路的布线中。此外，我们 建立了一个子宫内注射系统，将单个 II 型 Cdh 异位引入到 Ventral-ooDSGC 或 Nasal-ooDSGC 上，以精确定位调节 DS 电路模式的组合 Cdh。总的来说， 我们的研究试图揭示 Cdh 组合如何控制并行但不同的 DS 电路的形成。 对 II 型 Cdh 功能的全面研究将是解决长期悬而未决的问题的重大进展。 哺乳动物的神经发育。这些研究将在理解多重因素如何发挥作用方面迈出重要一步。 基因相互作用来指定复杂神经回路的连接。所确定的机制将具有重大意义 与整个中枢神经系统的选择性电路布线相关。