The Roles of Pioneer Neurons and Adhesion Molecules in Neuronal Migration

神经是我们大脑和脊髓的主要交流途径，由许多称为轴突的单独的交流纤维组成。每个轴突携带来自单个神经细胞（神经元）的信息。随着胚胎的发育，这些纤维必须正确地连接起来，才能形成工作的神经回路。在这些连接形成之前，神经元必须从它们出生的地方移动到它们将发挥作用的地方。此前，首席研究人员已经研究了控制面部表情的面部神经的这一过程，并发现单个“先锋”神经元引导其余神经元的运动到达最终目的地。先锋神经元从何而来，它们如何知道往哪里去，以及其他神经元如何知道如何跟随它们？该项目将在开发斑马鱼胚胎（面部神经与人类相似的动物）时解决这些问题。斑马鱼的胚胎是透明的，实验使用了经过特殊改造的斑马鱼，斑马鱼的面部神经元被荧光标记，使它们的细胞迁移可见。实验还将检查在细胞表面发现的对细胞迁移很重要的特定分子（细胞粘附分子）的作用。一种新的三维成像（光片显微镜）将用于测量细胞运动，新的软件将被开发出来，以可视化和分析细胞运动数据。一旦在芝加哥大学和海洋生物实验室进行开发和测试，这些软件工具将免费提供。该项目还将为高中生、本科生和研究生提供培训机会；引导中小学生参与研究；并通过科学与工业博物馆（MSI）的互动展览吸引公众。神经元亚群在神经上皮平面内切向迁移，通常距离很大。为了更好地理解对神经回路形成至关重要的切向迁移机制，本项目将重点研究面部分支运动神经元（fbmn），这些神经元经历了从鱼类到哺乳动物等脊椎动物中保守的切向迁移。这项研究将利用斑马鱼胚胎，因为它们易于获取，透明，并且是一个强大的遗传模型。迁移的fbmn将在带有遗传标记细胞的透明斑马鱼胚胎中成像，并使用薄片显微镜进行跟踪。首席研究员最近将先锋神经元描述为第一个迁移到后脑两侧的FBMN，并证明了该神经元的关键作用。目的1将通过建立其细胞起源和跟踪其随后的发展轨迹来研究新发现的先锋神经元。FBMN切向迁移也依赖于与两种不同的预铺轴突束的相互作用，这两种相互作用都依赖于粘附分子n -钙粘蛋白。目的2将研究n -钙粘蛋白在介导fbmn和轴突束之间相互作用中的作用，以及它在迁移过程中是否在神经元内自主起作用。其他对FBMN迁移重要的粘附分子将使用RNAseq进行鉴定。该项目的一个组成部分将是开发新的、广泛适用的计算工具来分析成像数据。

Nerves, the major communication pathways of our brain and spinal cord, are made of many individual communication fibers called axons. Each axon carries information from one single nerve cell (neuron). As an embryo develops, these fibers have to connect up correctly in order to make working neural circuits. Before these connections can form, the neurons have to move from the place they are born to the location where they will perform their role. Previously, the Principal Investigators have studied this process in the facial nerve, which controls facial expressions, and found that a single "pioneer" neuron guides the movement of the remaining neurons to their final destinations. Where do pioneer neurons come from, how do they know where to go, and how do other neurons know how to follow them? This project will address these questions in developing zebrafish embryos (animals with facial nerves similar to humans). Zebrafish embryos are transparent, and the experiments use specially-engineered zebrafish whose facial neurons are fluorescently labeled to make their cell migration visible. Experiments will also examine the roles of particular molecules found on the cell surface that are important for cell migration (cell adhesion molecules). A new kind of 3-dimensional imaging (light sheet microscopy) will be used to measure cell movements, and new software will be developed to visualize and analyze cell movement data. Once developed and tested at the University of Chicago and the Marine Biological Laboratory, these software tools will be made freely available. The project will additionally provide training opportunities for high school, undergraduate and graduate students; introduce elementary and middle school students to research; and engage the public via interactive displays at the Museum of Science and Industry (MSI).Subsets of neurons migrate tangentially within the neuroepithelial plane, often over significant distances. To better understand mechanisms underlying tangential migration that are important for neural circuit formation, this project focuses on facial branchiomotor neurons (FBMNs), which undergo a tangential migration that is conserved in vertebrates ranging from fishes to mammals. The study will utilize zebrafish embryos as they are accessible, transparent, and a powerful genetic model. Migrating FBMNs will be imaged in transparent zebrafish embryos with genetically marked cells, and tracked using light sheet microscopy. The Principal Investigator recently described the pioneer neuron as the first FBMN to migrate on each side of the hindbrain, and demonstrated the critical role of this neuron. Aim 1 will study the newly recognized pioneer neuron by establishing its cellular origins and tracking its subsequent trajectory through development. FBMN tangential migration also relies on interactions with two different pre-laid axon tracts and both interactions depend on adhesion molecule N-Cadherin. Aim 2 will investigate the role of N-Cadherin in mediating interactions between FBMNs and axon tracts, and whether it functions autonomously within neurons during migration. Additional adhesion molecules important for FBMN migration will be identified using RNAseq. An integral part of this project will be the development of new, broadly-applicable computational tools to analyze imaging data.