How temporal transcription factors regulate guidance cues and dendrite morphogenesis in Drosophila somatosensory circuits

摘要 适当发育的体感回路对于任何动物感知和与其相互作用是至关重要的 环境。躯体感觉电路的发展需要电路内的每个神经元正确地 定位其轴突和树突。这使它们能够建立特定的突触连接，并使电路 集合。在躯体感觉回路中，中间神经元是数量最多的神经元类型。另一个 类型是外周神经系统的感觉神经元。与感觉神经元相比，中间神经元 由于缺乏关于体感电路体系结构的工具和知识，正在进行研究。分子 已知的因素，如时间转录因子和引导信号，调节神经元的不同方面。 然而，这些分子因子在中间神经元中的作用尚未得到深入研究。 树突发育、突触伙伴选择和回路形成。我将测试中心假设 时间转录因子调节引导受体的表达，这建立了特定的树突状细胞 形态和突触连接。为了研究这一中心假说，在果蝇的神经索上，我 将使用神经母细胞3-3干细胞及其产生的EL中间神经元作为模型。在目标1中，我将测试 NB3-3中的工作假说，时间转录因子，Cas和NAB，激活了不同的指导集 早生和晚生EL子代中间神经元中的CUE受体，这决定了区别 树枝晶定位。我使用单细胞RNA测序，对Cas和NAB进行NB3-3特异性基因操作，以及 共聚焦显微镜检查树枝晶形态。我希望将时间转录的作用联系起来 影响引导线索受体表达的因素。此外，我预计将推出一种创新的 用排序的方法来分析我们目前的体感电路的发展。在目标2中，我将测试 在早期出生的EL树突中引导受体Roundout 3(Robo3)是必需的工作假说 并在较晚出生的EL树突中充足，以调节树突的形态发生和位置。我将表演Robo3 结合Robo3的亚细胞定位分析和功能获得和丧失分析来检测Robo3的功能 El树突中的Robo3。这一目标将有助于确定Robo3在中间神经元中的需求并开发新的 分析Robo3的定位。总体而言，这项提议将连接到以前不同的领域 体感回路的发展。这项工作也将使未来的研究能够调查广泛的 神经回路规范的保守性与神经发育病理治疗的发展 其中电路布线中断。

ABSTRACT Properly developed somatosensory circuits are critical for any animal to sense and interact with their environment. The development of somatosensory circuits requires that each neuron within the circuit to correctly position its axons and dendrites. This allows them to establish specific synaptic connections and for circuits to assemble. Within somatosensory circuits, interneurons represent are the most numerous neuron type. The other types are sensory neurons of the peripheral nervous system. In comparison to sensory neurons, interneurons are under investigated due to lack of tools and knowledge about somatosensory circuit architecture. Molecular factors, like temporal transcription factors and guidance cues, are known to regulate different aspects of neuronal development, however the role of these molecular factors has not been deeply investigated in interneuron dendrite development, synaptic partner selection, and circuit formation. I will test the central hypothesis that temporal transcription factors regulate guidance receptor expression, and this establishes specific dendritic morphologies and synaptic connections. To investigate this central hypothesis, in the Drosophila nerve cord, I will be using the neuroblast 3-3 stem cell and the EL interneurons it generates as a model. In Aim 1, I will test the working hypothesis in NB3-3, temporal transcription factors, Cas and Nab, activate different sets of guidance cue receptors in its early-born and late-born EL daughter interneurons, and that this determines differential dendrite positioning. I use single cell RNA-sequencing, NB3-3 specific gene manipulation of Cas and Nab, and confocal microscopy to examine dendrite morphology. I expect to connect the role of temporal transcription factors to the role of guidance cue receptor expression. Additionally, I expect to introduce an innovative sequencing approach to our current analysis of somatosensory circuit development. In Aim 2, I will test the working hypothesis that the guidance receptor Roundabout3 (Robo3) is necessary in early-born EL dendrites and sufficient in late-born EL dendrites to regulate dendrite morphogenesis and position. I will perform Robo3 subcellular localization assays alongside gain and loss-of-function assays of Robo3 to examine the function of Robo3 in EL dendrites. This aim will serve to identify the requirement of Robo3 in interneurons and develop new assays to analyze Robo3 localization. Overall, this proposal will connect to previous disparate areas of somatosensory circuit development. This work will also enable future research to investigate the broad conservation of neuronal circuit specification and development of therapies for neurodevelopmental pathologies in which circuit wiring is disrupted.