Circuit Assembly in the Vertebrate Retina

描述(申请人提供)：视觉需要从光感受器到视网膜神经节细胞(RGCs)的适当信息传输，RGCs是视网膜的输出神经元。这些信息由视网膜双极细胞(BCS)沿着许多解剖和功能上不同的通道分布。由于BC通道携带不同的色度和时间信息，RGC的光响应由其接收的BC输入的独特组合来塑造。到目前为止，只有少数功能定义的RGC类型的电路是已知的，很大程度上是因为通过连续电子显微镜进行重建在技术上具有挑战性且耗时。使用最先进的成像方法和分子工具来可视化突触和连接，我们能够很容易地通过光学显微镜重建这些电路。我们将建立并比较小鼠视网膜中三个不同功能的BC-RGC回路的连接模式，以了解新的原理或揭示BC输入可以塑造RGC输出的不同策略(目标1)。我们将研究神经传递的丧失(目标2)或视网膜神经元的死亡(目标3)如何改变视网膜内部的电路。由于活动阻断的效果可能会因神经传递在发育或疾病中受到干扰而有所不同，因此我们将确定BCS的输入和/或输出中断如何影响它们与视网膜节细胞的连接。我们将使用新型转基因小鼠，在这些小鼠中，传播受到不同方式的干扰，也将使用在少数或整个BCS群体中活动发生改变的小鼠。在目标3中，我们将确定成熟的BCs和RGC在来自一个或另一个群体的细胞被消融时重新连接的潜力。我们将通过使用转基因小鼠来实现这一点，在转基因小鼠中，细胞死亡的大小和时间可以控制。这些发现将对设计基于细胞的恢复视力的疗法具有特别重要的意义。总之，该项目的发现将显著增加我们对调节视网膜通道的功能、组装和修复的细胞机制的理解，这些通道是从光感受器向视网膜节细胞传递信息所必需的。

DESCRIPTION (provided by applicant): Vision requires proper information transfer from photoreceptors to retinal ganglion cells (RGCs), the output neurons of the retina. This information is distributed by retinal bipolar cells (BCs) along many anatomically and functionally distinct channels. Because BC channels carry different chromatic and temporal information, the light response of a RGC is shaped by the unique combination of BC input it receives. To date, the circuitry of only a few functionally defined RGC types is known, largely because reconstructions by serial electron microscopy are technically challenging and time consuming. Using state-of-the art imaging approaches and molecular tools to visualize synapses and connectivity, we are able to readily reconstruct these circuits by light microcopy. We will establish, and compare, the connectivity patterns of three functionally distinct BC-RGC circuits in the mouse retina, in order to learn new principles or uncover distinct strategies by which BC input can shape RGC output (Aim 1). We will investigate how loss of neurotransmission (Aim 2), or death of retinal neurons (Aim 3) alters circuitry in the inner retina. Because the effects of activity blockade can vary according to how neurotransmission is perturbed in development or in disease, we will determine how disruption of input and/or output of BCs influence their connectivity with RGCs. We will use novel transgenic mice in which transmission is perturbed in distinct ways, and also mice in which activity is altered in either a few or entire populations of BCs. In Aim 3, we will determine the potential of mature BCs and RGCs to re-connect when cells from one or the other population are ablated. We will do this by using transgenic mice in which the magnitude and timing of cell death can be controlled. These findings will be particularly significant for designing cell-based therapies to restore vision. Together, the discoveries of this project will significantly increase our understanding of the cellular mechanisms that regulate the function, assembly and repair of retinal channels necessary for conveying information from photoreceptors to RGCs.