Understanding the regulation of neuron cell number and arbor size

项目摘要/摘要 大脑如何产生正确数量的神经元，以及这些神经元如何决定其大小 乔木对感受区的神经支配是神经生物学中的一个重要问题。果蝇的视觉系统很难 连接并迭代地组织成专栏，为回答这些问题提供了一个极好的模型。 果蝇延髓多柱神经元每种细胞类型显示5到750个神经元；每个神经元类别 具有明显的形态，其茎在视叶的多个柱子上突出。主办实验室 已经获得了单细胞RNA测序(ScRNAseq)数据，这些数据确定了几乎所有 视叶神经元细胞类型在整个发育过程中。 这个项目的第一个目标是了解支配神经元的分子和细胞生物学机制。 数。在纽约大学克劳德·德斯普兰的指导下(K99阶段)，我将进行遗传学 决定性地解决细胞程序性死亡、神经干细胞分裂数和 神经上皮细胞的大小起源于调节多柱神经元产生的数量。我也会表演 谱系追踪实验，以确定分子上相似的细胞类型是否在同一时间产生 时间到了。和纽约大学医学中心的Holger Knaut一起，我将学习定量实时成像技术来区分 神经干细胞是否分裂有限次数以产生低丰度神经细胞，或者 未成熟祖细胞的细胞融合是否会影响细胞数量。 这个项目的第二个目标是确定决定大小的形态和遗传过程 以及多柱枝的方向，以允许它们覆盖不同的感受器区域。与 伊泰柳爱在纽约大学医学中心的生物信息学专业知识，我将在成年神经元上进行RNAseq 数量不足以在我们现有的scRNAseq数据集中识别。然后我将使用机器学习 在我们现有的scRNAseq文库中识别发育过程中的这些神经元的算法，从而识别 调节神经元数量和茎大小所需的候选基因(R00期)。我会把这些组合在一起 用活体成像的分子实验来定量描述多柱神经元如何决定 它们乔木的方位和大小。初步数据显示细胞死亡和神经上皮细胞的大小 起源区域在一定程度上决定了多柱神经元的数量；我还鉴定了一种神经肽，其 功能是调节神经元束大小的关键。我的工作将阐明神经元的分子基础 并确定少量存在的神经元如何调节其茎大小以确保其 环境是统一采样的，这是大多数物种许多大脑区域普遍存在的问题。

PROJECT SUMMARY/ABSTRACT How the brain generates the correct number of neurons and how these neurons determine the size of their arbors to innervate the receptor field is a critical question in neurobiology. The Drosophila visual system is hard wired and iteratively organized into columns, providing an excellent model to answer these questions. Drosophila medulla multicolumnar neurons exhibit 5 to 750 neurons per cell type; each neuron class possesses a distinct morphology and projects its arbors across multiple columns in the optic lobe. The host lab has obtained single-cell RNA sequencing (scRNAseq) data that determined the transcriptome of almost all optic lobe neuron cell types throughout development. The first aim of this project is to understand the molecular and cell biological mechanisms that dictate neuron number. Under the mentorship of Claude Desplan at New York University (K99 phase), I will perform genetics experiments that decisively address the role of programmed cell death, neural stem cell division number, and neuroepithelial size of origin in regulating the number of multicolumnar neurons produced. I will also perform lineage tracing experiments to determine whether molecularly similar cell types are generated at the same time. With Holger Knaut at NYU Medical Center, I will learn quantitative live imaging techniques to distinguish whether neural stem cells divide a limited number of times to generate low-abundance neural classes, or whether cell fusion of immature progenitors drives cell number. The second aim of this project is to determine the morphological and genetic processes that dictate the size and orientation of the arbors of multicolumnar to allow them to cover distinct receptor fields. With the bioinformatics expertise of Itai Yanai at NYU Medical Center, I will perform RNAseq on adult neurons that are not numerous enough to be identified in our existing scRNAseq data sets. I will then use machine learning algorithms to identify these neurons during development in our existing scRNAseq libraries and thus identify candidate genes required for the regulation of neuron number and arbor size (R00 phase). I will combine these molecular experiments with live imaging to quantitatively characterize how multicolumnar neurons determine the orientation and size of their arbors. Preliminary data indicates that cell death and the size of neuroepithelial region of origin in part dictate multicolumnar neuron number; I have also identified a neuropeptide whose function is essential for the regulation of neuron arbor size. My work will clarify the molecular basis of neuron abundance and determine how neurons present in small numbers regulate their arbor size to ensure that their environment is uniformly sampled, a problem common to many brain regions in most species.