Synapses in Regenerated Retina

 描述(申请人提供)：人类的视网膜退行性疾病和视网膜创伤会导致视网膜神经元的进行性丧失并导致视觉功能下降，部分原因是哺乳动物的视网膜不能通过产生替代神经元来内在地对神经元的丧失做出反应。NEI最近宣布了其大胆的目标，即“再生眼睛和视觉系统中的神经元和神经连接”。这一目标可以通过开发激活内源性视网膜细胞以表现出再生特性的策略来实现，和/或通过移植来自外部来源的替代视网膜神经元或其前体细胞来实现。实现这一大胆目标的挑战包括识别哺乳动物内源性细胞的激活机制，建立视网膜前体细胞以便以正确的数量和比例替换缺失的神经元，对于目前的R21应用来说，重要的是通过建立适当的突触连接将新神经元整合到视网膜电路中。斑马鱼已经成为获得视网膜再生过程知识的关键模型系统--将再生策略应用于哺乳动物视网膜所需的知识。我们以前的研究表明，斑马鱼再生的视网膜在功能上支持基本的反射和位置偏好行为，尽管再生的视网膜板层解体，再生的视网膜未能在每个板层内重建正常的视网膜神经元的二维模式。这些研究表明，即使在受损和再生的视网膜被破坏的环境中，再生的视网膜神经元也可以准确地重新连接自己。最终，了解视网膜回路重新布线的机制将是重要的。然而，在我们研究任何机制之前，有必要对再生过程中的重新连接过程以及成功重现本地突触连接的程度产生更完整的图景。因此，在R21的应用中，我们建议对斑马鱼未受损、再生和再生视网膜中的突触连接进行详细研究。我们将专注于视网膜双极细胞的连接，从而允许通过创新地使用几个 基因和分子工具可用于可视化这种视网膜细胞类型及其突触。将检验两个假设：1)再生视网膜的视网膜双极细胞连接重现正常成人视网膜的连接；2)轴突重组与视网膜再生过程中准确的重新连接有关。

 DESCRIPTION (provided by applicant): Retinal degenerative diseases and retinal trauma in humans cause progressive loss of retinal neurons and result in decreased visual function, in part because the mammalian retina does not intrinsically respond to the loss of neurons through the generation of replacement neurons. The NEI recently declared its Audacious Goal, to "regenerate neurons and neural connections in the eye and visual system." This goal may be accomplished by developing strategies for activating endogenous retinal cells to manifest regenerative properties, and/or by transplanting replacement retinal neurons or their progenitors from exogenous sources. Challenges to achieving this Audacious Goal include identification of mechanisms for the activation of endogenous cells in mammals, establishment of retinal progenitors such that the missing neurons are replaced in correct numbers and ratios, and importantly for the present R21 application, integration of new neurons into retinal circuitry through the establishment of appropriate synaptic connections. The zebrafish has emerged as a critical model system for gaining knowledge of the retinal regenerative process - knowledge required for applying regenerative strategies to the mammalian retina. Our prior studies indicated that the regenerated retina of the zebrafish functionally supports basic reflexes and place preference behaviors, despite disorganization of the regenerated retinal laminae and failure of regenerated retina to re-establish normal two- dimensional patterns of retinal neurons within each lamina. These studies suggest that regenerating retinal neurons may "re-wire" themselves accurately even in the disrupted environment of the damaged and regenerating retina. Ultimately it will be important to understand the mechanisms through which re-wiring of retinal circuitry takes place. However, before we pursue any mechanisms it is necessary to generate a more complete picture of the re-wiring process during regeneration and the extent of successful recapitulation of native synaptic connections. In this R21 application we therefore propose a detailed study of the synaptic connections in undamaged, regenerating, and regenerated retinas of the zebrafish. We will focus on connectomes of retinal bipolar cells, thus permitting the analysis of inner and outer retinal circuitry, through the innovative use of several genetic and molecular tools available for the visualization of this retinal cell type and its synapses. Two hypotheses will be tested: 1) that retinal bipolar cell connectomes of regenerated retina recapitulate those of undamaged adult retina; and 2) that neurite reorganization is associated with accurate re- wiring during retinal regeneration.