Deciphering the mechanisms underlying multicolumnar neuron pathfinding and specification in the Drosophila melanogaster optic lobe

破译果蝇视叶多柱神经元寻路和规范的机制

• 批准号: 9769762
• 负责人: Jennifer A Malin
• 金额: $ 6.56万
• 依托单位: NEW YORK UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-09-01 至 2020-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9769762
• 关键词: Animals; Antibodies; Axon; Blindness; Brain; Brain Injuries; Candidate Disease Gene; Cell Adhesion Molecules; Cells; Color; Columnar Cell; Complex; Cues; Data; Drosophila genus; Drosophila melanogaster; Exhibits; Eye; Fluorescent Antibody Technique; Ganglia; Genes; Genetic; Genetic Screening; Image; Imaging Techniques; Interneurons; Knowledge; Label; Location; Maps; Modeling; Molecular; Mothers; Motion; Mutate; Nervous system structure; Neurodegenerative Disorders; Neurology; Neurons; Neuropil; Optic Lobe; Optics; Output; Pattern; Photoreceptors; Process; Public Health; RNA Interference; Regenerative Medicine; Reporting; Research; Retina; Role; Scientist; Series; Signal Transduction; Specific qualifier value; Stains; System; Testing; Time; To specify; Vision; Visual; Visual system structure; Work; axon guidance; axonal guidance; axonal pathfinding; cell type; developmental neurobiology; droplet sequencing; experimental study; fly; imaginal disc; insight; morphogens; mutant; neuroblast; neuroepithelium; neuronal circuitry; notch protein; novel; receptive field; recruit; relating to nervous system; retinotopic; stem cell therapy; transcription factor; transcriptome; transcriptome sequencing; visual information; visual process

Project Summary/Abstract: How circuits in the brain are assembled is a crucial question in developmental neurobiology. The Drosophila visual system presents an elegant model to study this question; the optic lobes comprise ~60,000 neurons that allow the animal to perform sophisticated visual tasks. These cells are organized into 800 columns representing the 800 unit eyes (ommatidia) that perceive visual information in the retina. The medulla is the most complex neuropil of the visual system. Though each of the ten medulla layers is highly specialized, a consistent neuronal topology is maintained from layer to layer, in a phenomenon known as retinotopy. The host lab has identified three processes that generate the diversity of the over 80 neural types in the medulla. - First, each of the ~800 neuroblasts (NBs) sequentially expresses a series of six temporal transcription factors (tTFs), whose combination specifies different types of neuronal progeny. The integrated output of this system allows each NB to specify about 20 types of uni-columnar (UC) neurons at a 1:1 ratio to medulla columns. - Second, spatial cues within the OPC act in combination with tTFs to specify the fate of a second set of neurons—multicolumnar neurons (MC neurons)—that have a larger receptive field, exist at less than a 1:1 ratio to columns, and that innervate anywhere from two columns to half of the medulla, depending on the cell type. These MC neurons are only produced in subregions of the neuroepithelium. - Finally, Notch signaling (Non or Noff) further diversifies neuronal identity of the two neurons emerging from the division of the ganglion mother cell, the single transit-amplifying descendant of each NB. While MC neurons derive from restricted regions of the OPC, they find their targets and connect to the entire medulla. Although descriptions of MC neuron organization have been reported, the mechanisms behind how they find their targets are mostly unknown. Furthermore, previous research regarding MC neuron specification has focused on descendants of neuroblasts expressing the tTF Homothorax; the descendants of other tTF- expressing NBs have yet to be explored. My work seeks to understand how MC neurons are specified, and how this fate specification informs the cell's decisions in axon guidance, and thus, the establishment of retinotopy in this system. Specific aim 1 will look at the dynamics of MC neuron targeting within the medulla. We will use live imaging and immunofluorescence techniques to determine the lineage of MC neurons, identify the transcription factors expressed in these cells, and observe the mechanisms used by these cells to find their targets. Specific aim 2 will build upon the knowledge unearthed in Specific aim 1, and will use a candidate approach combined with transcriptome analysis of sorted MC cells in order to identify the genes required for MC neuron identity and pathfinding. Our research will provide novel insight into the physical and genetic mechanisms underlying how complex neurons are generated and find multiple targets on the retinotopic map, allowing us to better comprehend basic principles of nervous system assembly.

项目摘要/摘要： 大脑中的圆圈如何组装是发育神经生物学中的一个关键问题。 果蝇视觉系统提出了一个优雅的模型来研究这个问题。光学爱好包括约60,000 使动物可以执行复杂的视觉任务的神经元。这些细胞被组织成800 代表800个单位眼（Ommatidia）的列，这些视觉信息百分比在视网膜中。 这 髓质 是视觉系统中最复杂的神经胶体。尽管十个延髓层中的每一个都非常专业，但 在一种称为视网膜的现象中，一致的神经元拓扑保持了一致的层次。 主机实验室已经确定了三个过程，这些过程产生了髓质中80多种神经类型的多样性。 - 首先，〜800个神经细胞（NB）中的每一个都依次表达一系列六个临时转录因子 （TTFS），其组合指定了不同类型的神经元后代。该系统的集成输出 允许每个NB以1：1的比例指定约20种类型的Uni-Collumnar（UC）神经元与髓质柱。 - 第二，OPC ACT中的空间提示与TTF结合使用，以指定第二组的命运 神经元 - 多个神经元（MC神经元） - 具有较大的接受场，以小于1：1的比例存在 到列，并根据单元格类型支配从两个列到一半的髓质。 这些MC神经元仅在神经上皮的子区域产生。 - 最后，Notch信号（非或NOFF）进一步使两个神经元的神经元身份多样化。 神经节母细胞的划分，每个NB的单个传输放大后代。 尽管MC神经元来自OPC的受限区域，但他们找到了目标并连接到整个 尽管已经报道了MC神经元组织的描述，但如何背后的机制 他们发现自己的目标大多未知。此外，先前有关MC神经元规范的研究 专注于表达TTF同胸的神经细胞的后代；其他TTF-的后代 表达NBS尚未探索。我的工作试图了解如何指定MC神经元，并且 该命运规范如何在Axon指导中为细胞的决定提供信息，因此建立 该系统中的视网膜。具体目标1将介绍髓质内MC神经元靶向的动力学。 我们将使用实时成像和免疫荧光技术来确定MC神经元的谱系，识别 这些细胞中表达的转录因子，并观察这些细胞使用的机制 目标。特定目标2将基于特定目标1中发现的知识，并将使用候选人 方法与分类的MC细胞的转录组分析相结合，以识别所需的基因 MC神经元的身份和路径。我们的研究将提供对物理和遗传的新见解 基于如何生成复杂神经元并在视网膜图上找到多个目标的机制， 使我们能够更好地理解神经系统组装的基本原理。