Protocadherins in vertebrate self recognition

自我回避对神经系统的正常发育至关重要。生长中的树突和轴突 必须首先认识到，然后避免姐妹进程来自同一索马，以促进他们的 在环境中均匀分布。这种自我认知的过程最近被证明是 通过原钙粘蛋白家族介导。由于这一相对较新的发现， 关于原钙粘蛋白如何影响自我识别的研究。在果蝇中，自我识别是通过 主要是DSCAM 1。该提案的目标是利用DSCAM 1的广泛先前研究， 果蝇告知原钙粘蛋白在脊椎动物中的功能。果蝇的一个基本原理是 单个神经元表达不同的DSCAM 1亚型。这赋予每个神经元 独特的分子标记，使神经元能够识别自我和非自我。然而，确定 这一基本原理是否也适用于脊椎动物，实际上很难确定。的绝对数量 神经元，再加上缺乏可以标记神经元亚型的分子标记物，使得很难测试 每个神经元表达独特的原钙粘蛋白标记。为了解决这一问题，本提案将利用 嗅觉系统中强大的遗传工具，可以标记表达共同气味受体的神经元。 这使得分离和检查的原钙粘蛋白表达的所有嗅觉神经元的1/1000。 单细胞RNA分析将用于确定这些高度相关的神经元是否确实表达 不同的原钙粘蛋白组合。这种方法还将确定有多少原钙粘蛋白是 由给定神经元表达，以及表达是否随机。实体就雇员 然后使用典型的细胞粘附测定来测试组合对自我识别的影响。这项建议会 因此，它提供了迄今为止脊椎动物自我识别的最高分辨率测试之一， 并对比不同门的自我识别原则。理解原钙粘蛋白表达模式 在发展过程中出现的问题对人类健康有更广泛的影响。原钙粘蛋白与 是几种神经系统疾病背后的致病突变这些研究将为 了解哪怕是一个原钙粘蛋白的丢失如何导致疾病。

Self avoidance is essential for the proper development of the nervous system. Growing dendrites and axons must first recognize and then avoid sister processes derived from the same soma in order to promote their even distribution within the environment. This process of self recognition was recently demonstrated to be mediated via the protocadherin family. Because of this relatively new discovery, comparatively little is known regarding how protocadherins act to effect self recognition. In Drosophila, self recognition is mediated primarily by DSCAM1. The goal of this proposal is to draw upon extensive prior studies of DSCAM1 in Drosophila to inform protocadherin function in vertebrates. A fundamental principle in Drosophila is the finding that individual neurons express different complements of DSCAM1 isoforms. This endows each neuron with a unique molecular signature that enables the neuron to recognize self from non-self. However, determining whether this same basic principle also holds true in vertebrates is practically difficult. The sheer number of neurons, coupled with a lack of molecular markers that can label neuronal subtypes, has made it hard to test if each neuron expresses a unique protocadherin signature. To address this question, this proposal will utilize powerful genetic tools in the olfactory system that can label neurons expressing a common odorant receptor. This allows the isolation and examination of protocadherin expression in just 1/1000th of all olfactory neurons. Single cell RNA analysis will be used to determine whether these highly related neurons do indeed express different combinations of protocadherins. This approach will also determine how many protocadherins are expressed by a given neuron, and whether or not the expression appears random. The impact of these combinations on self recognition will then be tested using canonical cell adhesion assays. This proposal will therefore provide one of the highest resolution tests of self recognition to date in vertebrates, and will compare and contrast principles of self recognition across phyla. Understanding how protocadherin expression patterns arise during development has broader implications for human health. Protocadherins are associated with or are the causative mutation behind several neurological disorders. These studies will provide a foundation for understanding how loss of even a single protocadherin can lead to disease.