Circuit Assembly in the Vertebrate Retina

描述（由申请人提供）：中枢神经系统（CNS）的正常功能要求其许多细胞成分适当连接，以便处理和编码特定于大脑每个部分的信息。因此，确定中枢神经系统在发育过程中是如何精确连接起来的是非常重要的。尽管我们已经对神经回路发育的关键细胞和分子机制有了重要的了解，但仍有许多问题有待解决。发现这些机制需要阐明细胞如何相互作用以形成和维持连接的方法。我们的长期目标是了解在脊椎动物视网膜的许多细胞类型之间是如何建立高度特异性的突触连接的，主要有两个原因：视网膜是(1)视觉所必需的；(2)其紧密相关的结构和功能使其成为研究神经回路在发育过程中如何组织的绝佳模型。在本研究中，我们将重点关注视网膜的第一突触层，即外丛状层（OPL），视觉信号在该层内首先在视觉系统中进行处理。在OPL中，光感受器与双极细胞接触，然后将信号沿着不同的途径传递给视网膜输出细胞。水平细胞调节来自光感受器的信息。尽管OPL的视觉处理很重要，但在开发过程中对其组装的了解很少。我们建议使用并产生转基因小鼠来研究各种视网膜外细胞类型如何相互作用以在OPL中建立电路。我们将标记光感受器，双极和水平细胞在活的动物，通过使他们表达荧光蛋白使用细胞特异性启动子。最先进的光学成像方法将应用于可视化和跟踪这些细胞如何相互形成适当接触的过程。我们还将使用和产生突变小鼠来解决水平细胞在调节OPL结构和功能发育中的重要性，水平细胞发育最早。我们的研究结果应该能让我们更深入地了解细胞之间的相互作用如何导致回路的建立，从而进一步了解神经系统的发育障碍。我们的发现可能有助于未来研究的重点，旨在设计在创伤或疾病中重建视网膜功能的策略。

DESCRIPTION (provided by applicant): The proper functioning of the central nervous system (CNS) requires that its many cellular components are connected appropriately, in order to process and encode information specific to each part of the brain. Thus, determining how the CNS is wired up precisely during development is fundamentally important. Although we have gained a significant understanding of the cellular and molecular mechanisms that are critical for circuit development, much has yet to be unraveled. Discovering these mechanisms requires approaches that will elucidate how cells interact with each other to form and maintain connections. Our long term goal is to understand how highly specific synaptic connections are established between the many cell types of the vertebrate retina, largely for 2 reasons: The retina is (1) essential for vision; and (2) its strongly correlated structure and function makes it an excellent model for investigating how neural cricuits are organized during development. In this proposal, we will focus on the first synaptic layer of the retina, the outer plexiform layer (OPL), within which visual signals are first processed in the visual system. In the OPL, photoreceptors contact bipolar cells that then relay signals along distinct pathways to retinal output cells. Horizontal cells modulate information conveyed from photoreceptors. Despite the importance of visual processing by the OPL, little is understood concerning its assembly during development. We propose to use and generate transgenic mice to examine how the various outer retinal cell types interact with each other to establish circuitry in the OPL. We will label photoreceptors, bipolar and horizontal cells in live animals, by causing them to express fluorescent proteins using cell-specific promoters. State-of-the-art optical imaging methods will be applied to visualize and follow how processes of these cells come to form appropriate contact with each other. We will also use and generate mutant mice to address the importance of horizontal cells, which develop earliest, in regulating the structural and functional development of the OPL. Our results should provide a deeper understanding of how interactions between cells lead to the establishment of their circuits, and thus provide further insight into developmental disorders in the nervous system. Our findings could potentially help focus future investigations aimed at designing strategies to re-establish retinal function in trauma or disease.