Forward Genetic Analysis of Congenital Defects in Cortical Circuits and Structure

描述（由申请人提供）：哺乳动物新皮层是一个巨大的细胞网络，每个细胞都有数千个连接，并且一系列神经系统疾病可能由不适当的皮层结构或连接引起。这些先天性大脑缺陷中的许多都有遗传起源，但我们仍然缺乏对相关基因和机制的全面了解。本申请的总体目标是在小鼠和人类中使用正向遗传方法来鉴定和验证对皮层电路和整体结构的发育重要的新等位基因。我们的中心假设是，在小鼠和人类中的协同和无偏见的向前遗传方法将导致皮质回路形成和结构发育的遗传学的基本发现。这项研究的基本原理是，通过正向遗传学方法识别新基因，这些基因是使用人类和小鼠遗传学进行正常皮质发育所需的，然后我们将利用这些信息和工具在后续研究中研究人类皮质畸形的病因机制。我们将检验这一中心假设，并通过追求以下三个具体目标来实现本申请的目标：1）在小鼠中使用正向遗传学以有效地产生和捕获对皮层回路形成和结构发育重要的基因座中的遗传突变，2）鉴定和验证皮层回路形成和结构性脑缺陷的新小鼠模型中的因果突变，以及3）应用下一代测序方法来鉴定导致人类运动障碍和结构性脑缺陷的突变。目的是通过在小鼠中加入一种新的转基因报告基因的ENU诱变方法来实现的，该报告基因在皮层V层锥体神经元中特异性表达。然后克隆突变并通过许多功能研究进行验证。人类遗传学研究是通过对精心挑选的运动障碍和结构性脑畸形的家族病例进行外显子组测序来进行的。这些研究将确定哺乳动物前脑结构和功能所必需的几个基因。这项工作的意义在于对皮质电路和结构的具体应用，并且这种无偏见的方法有能力在神经系统疾病中发现全新的途径。使用小鼠和人类遗传学的协同方法来专门查询神经发育的这些方面，可以从根本上了解发育和疾病的遗传学。这些知识不仅对进一步理解神经发育的基本机制至关重要，而且通过鉴定许多潜在的治疗靶点具有直接的临床意义。此外，这些小鼠模型提供了可重复使用的资源，以直接表征突变基因在神经发育中的作用，并可能作为测试未来治疗干预的工具。总之，这些发现适用于基础发育神经生物学，儿童和成人神经学，人类遗传学和遗传咨询。

DESCRIPTION (provided by applicant): The mammalian neocortex is an enormous network of cells, each making thousands of connections and an array of neurological conditions can result from inappropriate cortical structure or connectivity. Many of these congenital brain defects have a genetic origin but we still lack a full understanding of the genes and mechanisms involved. The overall objective of this application is to use forward genetic approaches in mouse and human to identify and validate novel alleles important for development of cortical circuitry and overall structure. Our central hypothesis is that a synergistic and unbiased forward genetic approach in mouse and human will lead to fundamental discoveries in the genetics of cortical circuit formation and structural development. The rationale of this proposed research is that by identifying novel genes through forward genetic approaches which are required for normal cortical development using both human and mouse genetics, we are then positioned to use this information and tools to study the etiological mechanisms of human cortical malformations in subsequent studies. We will test this central hypothesis and accomplish the goals of this application by pursuing the following three specific aims: 1) use forward genetics in the mouse to efficiently generate and capture genetic mutations in loci important for cortical circuit formation and structural development, 2) identify and validate causal mutations in novel mouse models of cortical circuit formation and structural brain defects, and 3) apply next-generation sequencing approaches to identify mutations leading to human movement disorders and structural brain defects. The aims are accomplished by an ENU mutagenesis approach in the mouse with the addition of a novel transgenic reporter which is expressed specifically in cortical layer V pyramidal neurons. The mutations are then cloned and validated through a number of functional studies. The human genetics studies are performed with the application of exome sequencing to carefully selected familial cases of movement disorders and structural brain malformations. These studies will identify several genes essential for mammalian forebrain structure and function. The significance of this work is found in the specific application to cortial circuitry and structure, and that an unbiased approach such as this has the capability to implicate entirely new pathways in neurological disease. A synergistic approach using both mouse and human genetics to specifically query these aspects of neural development allows fundamental insights into the genetics of development and disease. Such knowledge is not only critical to further understand the basic mechanisms of neurodevelopment, but also has immediate clinical relevance through identification of a number of potential therapeutic targets. Furthermore, these mouse models provide a reusable resource to directly characterize the role of the mutated gene in neurodevelopment, and potentially serve as a tool to test future therapeutic interventions. Taken together, these findings are therefore applicable to basic developmental neurobiology, pediatric and adult neurology, human genetics and genetic counseling.