Linking neuronal identity transcription factors to neural circuit establishment and maintenance

项目摘要/摘要 神经元同一性是在发育过程中产生的，具有神经元特异性的同一性 基因表达、轴突/树突形态和连接性。同源结构域转录因子 (Tf)是建立基因表达和神经元形态所必需的，但它们是否 神经元连接所需的信息尚不清楚。了解发展过程 一般说来，产生神经元的同一性，特别是连接性，对于理解 大脑的组装和功能。一个有吸引力的模型是同源结构域转录因子-已知调节 神经元分子和形态的同一性-也促进细胞表面的表达 允许形成高度特异的神经连接的分子。之间的联系 单个神经元组成神经回路，允许感觉、运动和认知。 在整个生命中，正常的电路功能依赖于持续的电路重构，无论是突触还是 从结构上讲。有趣的是，同源结构域转录因子在成年神经元中表达，远远晚于神经元。 身份已经确定。我假设神经细胞需要同源结构域的转录因子 在整个生命周期内建立和维护电路。为了测试这一点，我执行了一个 运动神经回路功能所需同源结构域转录因子的系统筛选 果蝇，月球漫步者下行神经元(MDN)和派1环路。我已经确认了16个 MDN或Pair1光遗传诱导运动所需的同源结构域TF。在目标1中，我将测试 这16个同源结构域TF如何通过分析分子同一性来促进神经元同一性， 轴突/树突形态和连通性。我的试点实验已经表明， 同源结构域Tf双标是连通性所必需的，但不需要分子同一性或形态。在AIM 2，我将利用MDN-Pair1电路在果蝇变态过程中是如何重构并持续存在的 在成虫身上。我将分析建立MDN-Pair1连接所需的TF是否也 在整个成年期间维持MDN-Pair1回路所必需的。我的飞行员数据显示双曲面 在成年的Pair1神经元中也有表达。我的首要目标是促进对 发育机制，特别是同源结构域转录因子，是如何在 在经历了一段时间的可塑性/重塑后，开发和维护电路。考虑到那只苍蝇和 哺乳动物的神经发生有许多保守的特征，即同源结构域的转录因子高度 在物种之间是保守的，异常的神经回路被牵连到 神经发育和精神障碍，我们希望我们的结果是可翻译的和 在治疗上有意义。

PROJECT SUMMARY/ABSTRACT Neuronal identity is generated during development, with identity characterized by neuron-specific gene expression, axon/dendrite morphology, and connectivity. Homeodomain transcription factors (TFs) are required for establishing gene expression and neuronal morphology, but whether they are required for neuronal connectivity is unknown. Understanding the developmental processes generating neuronal identity in general, and connectivity in particular, is essential for understanding brain assembly and function. An attractive model is that homeodomain TFs – known to regulate neuronal molecular and morphological identity – also facilitate the expression of cell surface molecules that allow the formation of highly-specific neural connections. Connections between individual neurons contribute to neural circuits, which allow sensation, movement and cognition. Proper circuit function throughout life relies on continued circuit remodeling, both synaptically and structurally. Interestingly, homeodomain TFs are expressed in adult neurons, well after neuronal identity has been established. I hypothesize that the homeodomain TFs are required for neural circuit establishment and maintenance throughout life. To test this, I have performed a systematic screen for homeodomain TFs required for the function of a locomotor neural circuit in Drosophila, the Moonwalker Descending Neuron (MDN) and Pair1 circuit. I have identified 16 homeodomain TFs required for MDN or Pair1 optogenetic induced locomotion. In Aim 1, I will test how these 16 homeodomain TFs contribute to neuronal identity by assaying molecular identity, axon/dendrite morphology, and connectivity. My pilot experiments have already shown that the homeodomain TF Bicoid is required for connectivity but not molecular identity or morphology. In Aim 2, I will utilize how the MDN-Pair1 circuit is remodeled during Drosophila metamorphosis and persists in the adult fly. I will assay whether the TFs required for establishing MDN-Pair1 connectivity are also required for maintaining the MDN-Pair1 circuit throughout adulthood. My pilot data shows that Bicoid is also expressed in the adult Pair1 neurons. My overarching goal is to advance the understanding of how developmental mechanisms, specifically homeodomain TFs, establish circuits during development and maintain circuits after periods of plasticity/remodeling. Given that fly and mammalian neurogenesis share many conserved features, that homeodomain TFs are highly conserved between species, and that aberrant neural circuits have been implicated in neurodevelopmental and psychiatric disorders, we expect our results to be both translatable and therapeutically relevant.