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

摘要 适当发展的躯体感觉回路对于任何动物感知和与它们的身体互动都是至关重要的。 环境躯体感觉回路的发展需要回路中的每个神经元正确地 定位轴突和树突。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 类型是周围神经系统的感觉神经元。与感觉神经元相比，中间神经元 由于缺乏有关躯体感觉电路结构的工具和知识，分子 已知时间转录因子和引导因子等因子调节神经元的不同方面， 然而，这些分子因子在中间神经元发育中的作用尚未得到深入研究。 树突发育、突触伴侣选择和回路形成。我将检验中心假设， 时间转录因子调节导向受体的表达，这建立了特定的树突状细胞， 形态学和突触连接。为了研究这一中心假设，在果蝇的神经索中，我 将使用神经母细胞3-3干细胞和它产生的EL中间神经元作为模型。在目标1中，我将测试 在NB 3 -3中的工作假设，时间转录因子Cas和Nab激活不同的指导 提示受体在其早期出生和晚期出生的EL子中间神经元，这决定了差异 树突定位我使用单细胞RNA测序，NB 3 -3特异性Cas和Nab基因操作， 共聚焦显微镜检查树突形态。我希望把时间转录的作用 因子对导向信号受体表达的作用。此外，我还希望引入一种创新的 我们目前对体感回路发育的分析采用了一种排序方法。在目标2中，我将测试 工作假设，指导受体Roundabout 3（Robo 3）是必要的，在早期出生的EL树突 在晚生EL树突中足以调节树突形态发生和位置。我会表演机器人3 亚细胞定位测定以及Robo 3的获得和丧失功能测定，以检查 EL树突中的Robo 3。这一目标将有助于确定Robo 3在中间神经元中的需求，并开发新的 用于分析Robo 3定位的测定。总的来说，这项提案将连接到以前不同的领域， 体感回路发育这项工作也将使未来的研究能够调查广泛的 保护神经元回路特化和开发神经发育病理学的治疗方法 其中电路布线被中断。

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.