Cell Biology of the Retina

描述（由申请人提供）：我们研究的目的是了解哺乳动物的视网膜如何分析视觉世界，并将其空间，时间和色彩对比编码为发送到大脑的动作电位信息。在视网膜中，多巴胺是负责许多导致神经适应光的事件的调节剂。为了确定控制多巴胺释放的机制和神经网络，我们在小鼠中标记了遗传多巴胺能无长突细胞（DA细胞），因此可以在视网膜分离后在体外研究它们的生理学。我们还开发了一种技术来研究单个神经元中的全局基因表达。本申请具有以下目的：（i）我们将检验这样的假设，即除了多巴胺之外，DA细胞还通过胞吐作用在它们的整个表面上以及在它们与AII无长突细胞的突触处释放GABA，AII无长突细胞是将视杆细胞信号传递给视锥双极细胞的神经元。(ii)我们将研究DA细胞的光反应的细胞内记录在完整的小鼠视网膜。(iii)通过分析基因表达的高密度阵列的寡核苷酸探针覆盖转录的小鼠基因组，我们将编译一个全面的列表中包含的DA细胞的成绩单。知识储备的离子通道，递质受体，G-蛋白偶联的第二信使途径的组件和分泌的神经活性分子中所载的DA细胞将使我们能够制定有意义的假设，可以通过实验测试的新功能。最后，我们将比较DA细胞的转录组与其他两种类型的视网膜神经元，2型儿茶酚胺能无长突和杆双极。除了新分子的存在之外，我们还将寻找神经元细胞类型概念核心问题的答案：我们希望发现细胞类型特异性分子，并确定三种类型神经元在光信号处理中执行的独特功能的“分子特征”。(iv)我们将通过电子显微镜鉴定控制DA细胞在光和暗中活动的神经元。这些研究对于理解视网膜的视觉机制至关重要。

DESCRIPTION (provided by applicant): The objective of our research is to understand how the retina of mammals analyzes the visual world and encodes its spatial, temporal and chromatic contrast into a message of action potentials which is sent to the brain. In the retina, dopamine is the modulator responsible for many of the events that lead to neural adaptation to light. To identify the mechanisms and neural networks that control the release of dopamine, we labeled genetically dopaminergic amacrine cells (DA cells) in the mouse and could therefore investigate their physiology in vitro after dissociation of the retina. We also developed a technique to study global gene expression in single neurons. The present application has the following aims: (i) we will test the hypothesis that DA cells, in addition to dopamine, release GABA by exocytosis both over their entire surface and at their synapses with AII amacrine cells, the neuron that transfer rod signals to cone bipolar cells. (ii) We will investigate the light responses of DA cells by intracellular recordings in the intact mouse retina. (iii) By profiling gene expression on high-density arrays of oligonucleotide probes covering the transcribed mouse genome, we will compile a comprehensive list of the transcripts contained in DA cells. Knowledge of the repertory of ion channels, transmitter receptors, components of G-protein-coupled second messenger pathways and secreted neuroactive molecules that are contained in DA cells will allow us to formulate meaningful hypotheses about novel functions that can be tested experimentally. Finally, we will compare the transcriptome of DA cells with that of two other types of retinal neurons, type 2 catecholaminergic amacrines and rod bipolars. In addition to the presence of novel molecules, we will be searching for answers to questions that are at the very heart of the concept neuronal cell type: we want to uncover cell-type specific molecules and identify a "molecular signature" for the unique functions that are carried out by the three types of neurons in the processing of light signals. (iv) We will identify by electron microscopy the neurons that control the activity of DA cells in light and darkness. These studies are crucial to the understanding of the mechanism of vision in the retina.