BRC-BIO: The role of serotonin signaling in autoregulation of axon morphology, connectivity, and behavior in Drosophila

神经系统的主要作用是感知我们周围的环境，并引发适当的行为反应。这是由复杂的神经回路控制的，这些神经回路通过被称为轴突的长电缆状结构相互连接。一组重要的轴突来自于产生血清素的脑细胞，它们与神经系统中的回路结合，调节情绪、睡眠、食欲和认知等行为。最终，这些行为输出是由轴突的精确生长和连接决定的。PI和该领域的其他人最近的工作表明，在发育的早期阶段，产生血清素的脑细胞使用血清素本身来帮助形成其轴突。这项研究将利用果蝇（Drosophila melanogaster）的尖端遗传工具，了解这种分子机制如何在细胞内工作，它如何形成大脑回路，以及它如何影响行为输出。果蝇的神经系统由与人类神经系统相同的基本组成部分组成，这些基本组成部分组装并指导神经活动。因此，所获得的知识将有助于深入了解发育过程中异常的血清素暴露如何导致人类行为障碍。这些研究将通过有偿研究职位为学生提供遗传学、细胞生物学和神经科学等多学科研究经验。通过减少在一个为低收入和第一代大学生提供服务的研究所进行本科研究的经济障碍，该项目推进了NSF培养多元化STEM劳动力的使命。初步体外实验表明5-羟色胺受体5-HT1A启动信号事件，自动调节5-羟色胺能轴突的生长。该项目的第一个目标是通过对果蝇初级5-羟色胺能神经元中候选5-羟色胺信号通路的遗传和药理学操作，结合轴突生长的形态计量学分析和肌动蛋白动力学的活细胞成像，确定5-HT1A参与的细胞内机制。该项目的第二个目标是确定如何使用单个血清素能神经元（SP2-1）作为模型的自动调节形状解剖电路。该神经元支配幼虫的视觉系统，可以使用现有的遗传工具选择性地标记，允许在各种实验条件下对SP2-1神经元进行3D重建。一种新的顺行跨突触脑弓标记方法将用于询问血清素信号的变化如何改变sp1 -1神经元的连通性。第三个目标是了解5 -羟色胺自动调节的缺陷如何通过操纵5 -羟色胺信号和将SP2-1形态的变化与视觉行为的变化相关联来改变行为输出。这些研究将首次提供血清素自动调节的分子机制及其对血清素能系统形态和功能发育的影响。这个研究管道也将作为未来研究的基础，包括分析不同的细胞类型和/或电路、行为范例、其他信号分子和发育阶段。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The primary role of the nervous system is to perceive conditions in our surroundings and elicit the appropriate behavioral response. This is controlled by complex neural circuits that are interconnected through long cable-like structures called axons. One important group of axons arises from serotonin-producing brain cells, which integrate with circuits throughout the nervous system to modulate behaviors such as mood, sleep, appetite, and cognition. Ultimately, these behavioral outputs are determined by the precise growth and wiring of axons. Recent work by the PI and others in the field has shown that serotonin-producing brain cells use serotonin itself to help shape its axons during early stages of development. This research will utilize cutting-edge genetic tools available in fruit flies, Drosophila melanogaster, to understand how this molecular mechanism works inside the cells, how it shapes circuits in the brain, and how it impacts behavioral output. The fruit fly nervous system is built with the same basic components, which assemble and direct neural activities as they do in the human nervous system. The knowledge gained will therefore provide insight into how abnormal serotonin exposure during development can lead to behavioral disorders in humans. These studies will provide students with multidisciplinary research experiences in genetics, cellular biology, and neuroscience through paid research positions. By reducing financial barriers to undergraduate research at an institute serving large populations of low-income and first-generation college students, this project advances the NSF mission to grow a diverse STEM workforce.Preliminary in vitro experiments indicate the serotonin receptor 5-HT1A initiates signaling events that autoregulate serotonergic axon outgrowth. The first objective of this project is to determine the intracellular mechanisms 5-HT1A engages using genetic and pharmacological manipulation of candidate serotonin signaling pathways in primary Drosophila serotonergic neurons paired with morphometric analysis of axon outgrowth and live cell imaging of actin dynamics. The second objective of this project is to determine how autoregulation shapes anatomical circuits using a single serotonergic neuron (SP2-1) as a model. This neuron innervates the larval visual system and can be labeled selectively using existing genetic tools, allowing 3D reconstructions of the SP2-1 neuron under various experimental conditions. A novel anterograde trans-synaptic Brainbow labeling approach will be used to ask how changes in serotonin signaling alter connectivity of the SP2-1 neuron. The third objective is to understand how defects in serotonin autoregulation can alter behavioral outputs by manipulating serotonin signaling and correlating changes in SP2-1 morphology to changes in vision-based behaviors. These studies will provide the first molecular mechanism of serotonin autoregulation and its impact on the morphological and functional development of the serotonergic system. This research pipeline will also serve as a foundation for future research including analysis of different cell types and/or circuits, behavioral paradigms, other signaling molecules, and developmental stages.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.