Identification of genes that regulate electrical synapse formation in vivo

描述（申请人提供）：本项目的长期目标是了解体内调节神经回路和电突触形成的分子通路。神经回路由突触组织，突触是粘附和通信的专门场所，其模式和特性形成所有大脑功能的基础。突触可以是化学的，其中信号通过神经递质的释放和接收来传递，也可以是电的，其中信号直接通过神经元之间的间隙连接。其中，化学突触近年来受到了更多的关注，然而越来越多的证据表明，电突触在大脑中广泛存在，它们调节从视觉到记忆和学习的神经处理。神经回路和突触形成的基础是遗传机制，确保神经元选择适当的目标，并将复杂的突触机制招募到接触部位。然而，调控这些过程的基因还没有很好的理解，特别是在电突触形成方面。我们建议建立斑马鱼Mauthner（M）电路作为理解神经元靶选择和电突触形成的遗传基础的模型。M回路简单易行，是典型的逃避反应行为所必需的。这些特性，结合专门标记神经回路细胞及其定型化学和电突触的遗传工具，提供了一个独特的机会来发现影响电突触发生的突变，了解这些缺陷的细胞基础，并评估其行为后果。目的是证明影响M电突触形成的突变可以使用正向遗传筛选（Aim1）来鉴定，以证明这些突变在细胞生物学水平上特异性地影响电突触形成（Aim2），并且它们在M介导的逃避反应水平上具有明显的功能缺陷（Aim3）。总的来说，这项建议将评估是否M电路是一个合适的平台，研究脊椎动物中枢神经系统电突触的形成，这将奠定基础，解开潜在的细胞和分子机制。这些知识是至关重要的，因为突触发育或功能的缺陷与许多神经发育障碍有关，包括自闭症和癫痫，以及与年龄有关的疾病，如阿尔茨海默氏症。对突触如何建立的基本理解对于改善神经疾病的检测和指导治疗的发展至关重要。 公共卫生相关性：中枢神经系统包含数十亿个神经元，这些神经元被组织成连接的电路，允许信息的传输和处理，最终导致感知，思想和行为。很明显，大脑不仅仅是一堆随机连接的电线，而是创造了非常特定和可复制的电路，而其发展背后的基因缺陷导致了许多疾病，如自闭症和癫痫。这项研究旨在研究基因如何调节神经元回路的产生，从而深入了解这一基本过程和知识，这对于指导未来试图修复患病大脑的治疗工作是必要的。

DESCRIPTION (provided by applicant): The long-term goal of this project is to understand the molecular pathways that regulate neural circuit and electrical synapse formation in vivo. Neural circuits are organized by synapses, which are specialized sites of adhesion and communication whose patterns and properties form the basis of all of brain function. Synapses can be either chemical, where signals are transmitted via neurotransmitter release and reception, or electrical, where signals pass directly through gap junctions between neurons. Of these, the chemical synapse has received more attention in recent years, however growing evidence suggests that electrical synapses are widespread in the brain where they modulate neural processing from vision to memory and learning. Underlying neural circuit and synapse formation are genetic mechanisms ensuring that neurons select appropriate targets and recruit the complex synaptic machinery to the sites of contact. However, the genes that regulate these processes are not well understood, especially in regard to electrical synapse formation. We propose to establish the zebrafish Mauthner (M) circuit as a model for understanding the genetic basis of neuronal target selection and electrical synapse formation. The well-characterized M circuit is simple and accessible, and is necessary for a stereotypical escape response behavior. These properties, in conjunction with genetic tools that specifically mark the cells of the neural circuit and their stereotyped chemical and electrical synapses, provide a unique opportunity to find mutations that affect electrical synaptogenesis, to understand the cellular basis of these defects, and to assess their behavioral consequences. The goal is to demonstrate that mutations affecting M electrical synapse formation can be identified using a forward genetic screen (Aim1), to demonstrate that these mutations specifically affect electrical synapse formation at the cell- biological level (Aim2) and that they have functional deficits that are evident at the level of the M-mediated escape response (Aim3). Overall this proposal will evaluate whether the M circuit is a suitable platform for studying vertebrate CNS electrical synapse formation; this will lay the groundwork for unraveling the underlying cellular and molecular mechanisms. Such knowledge is critical given that defects in synapse development or function are associated with a number of neurodevelopmental disorders, including autism and epilepsy, and also age-related diseases, such as Alzheimer<s. A fundamental understanding of how synapses are built is essential for improved detection of neurological disease and for guiding the development of therapies. PUBLIC HEALTH RELEVANCE: The central nervous system contains billions and billions of neurons that are organized into connected circuits that allow for the transfer and processing of information, ultimately leading to perception, thought, and behavior. It is clear that the brain is not just a jumble of wires randomly linked to one another, but instead very specific and reproducible circuits are created and defects in the genes underlying their development lead to a number of diseases such as autism and epilepsy. This study proposes to investigate how genes regulate the creation of neuronal circuits, giving insight into this fundamental process and knowledge that is necessary to guide future therapeutic work that attempts to fix diseased brains.