Molecular Mechanisms of Electrical Synapse Formation in Vivo

大脑的所有功能，从感官感知到行为，都是从大脑的模式和属性中衍生出来的 数十亿(人类)单个神经元之间的突触连接。这个项目的长期目标是 利用有焦点的脊椎动物模型了解体内调节突触形成的分子途径 在被忽视的电子突触上。电突触是人与人之间直接交流的场所 允许离子和小分子通过的神经元。它们对神经回路有广泛的贡献 形成和功能，无论是在发育过程中，还是在成年期，它们对感觉都有贡献 知觉、神经元间处理和运动输出。然而，控制这一过程的分子机制 对电突触的形成知之甚少。这项提议利用斑马鱼的莫特纳回路来 研究电突触形成和功能的遗传学、细胞生物学和生物化学。莫特纳 神经元是可以单独识别的，它们在突触前和突触后的伙伴、突触和功能是可以识别的 在一个活生生的脊椎动物胚胎中精美地可视化。经典的正向和新颖的反向遗传屏幕 鉴定了形成Mauthner电突触的神经元间通道的连接蛋白，发现 有专门的突触前和突触后连接蛋白，并发现了Neurobeachin，一种后高尔基体贩运 蛋白和紧密连接蛋白1b(Tjp1b)，膜相关鸟苷酸激酶(MAGUK)家族 电突触形成所需的支架。这些发现表明，电突触是 由通常不被认识的分子复杂性组成的；他们进一步表明，错综复杂的 需要生化机制来控制这些关键部位的形成、功能和可塑性。 神经元通讯。本方案的目的是研究电突触的细胞生物学机制。 形成，检验了电子突触需要突触后定位和功能的假设 Tjp1b来稳定突触上的连接蛋白。AIM2研究了生物化学机制 突触发生，检验Tjp1b和连接蛋白之间的直接相互作用是 定位到突触所需的。Aim3希望扩大所需蛋白质的分子谱系 电突触的形成，并提供了一种新的观点，即电突触是复杂的多分子 机器。鉴于电突触对大脑早期发育的连接至关重要，它们可能是 错综复杂地与发育性连线障碍有关。事实上，Neurobeachin和MAGUK都是 与自闭症和其他神经发育障碍有关。拟议的研究将提供新的 深入了解电突触的形成机制，为电突触的识别奠定基础。 治疗复杂神经发育障碍的靶点。

All of brain function, from sensory perception to behavior, is derived from the pattern and properties of the synaptic connections among billions (in humans) of individual neurons. The long-term goal of this project is to understand molecular pathways that regulate synapse formation in vivo using a vertebrate model with a focus on the underappreciated electrical synapse. Electrical synapses are sites of direct communication between neurons that allow the passage of ions and small molecules. They contribute extensively to neural circuit formation and function, both during development as well in adulthood where they contribute to sensory perception, interneuron processing, and motor output. However, the molecular mechanisms controlling the formation of electrical synapse are poorly understood. This proposal utilizes the zebrafish Mauthner circuit to investigate the genetics, cell biology, and biochemistry of electrical synapse formation and function. Mauthner neurons are individually identifiable and their pre- and postsynaptic partners, synapses, and function are exquisitely visualized in a living, vertebrate embryo. Classic forward and novel reverse genetic screens have identified the Connexins that form the inter-neuronal channels of the Mauthner electrical synapses, found that there are dedicated pre- and postsynaptic Connexins, and identified Neurobeachin, a post-Golgi trafficking protein, and Tight Junction Protein 1b (Tjp1b), a membrane-associated guanylate kinase (MAGUK) family scaffold, as being required for electrical synapse formation. These findings suggest that electrical synapses are comprised of a molecular complexity that is not generally appreciated; they further suggests that intricate biochemical mechanisms are required to control the formation, function, and plasticity of these critical sites of neuronal communication. Aim1 of this proposal examines the cell biological mechanisms of electrical synapse formation, examining the hypothesis that electrical synapses require the postsynaptic localization and function of Tjp1b to stabilize Connexins at the synapse. Aim2 examines the biochemical mechanisms of synaptogenesis, examining the hypothesis that a direct interaction between Tjp1b and the Connexins is required for localization to the synapse. Aim3 looks to expand the molecular repertoire of proteins required for electrical synapse formation, and provides a new view of electrical synapses as complex multi-molecular machines. Given that electrical synapses are essential to early developmental wiring of the brain, they may be intricately linked to developmental disorders of wiring. Indeed, both Neurobeachin and the MAGUKs are associated with autism and other neurodevelopmental disorders. The proposed studies will provide novel insight into the mechanisms of electrical synapse formation and provide a foundation for the identification of targets for therapy of complex neurodevelopmental disorders.