Plasticity of auditory electrical synapses

听觉电突触的可塑性

• 批准号: 10586498
• 负责人: Alberto E Pereda
• 金额: $ 63.16万
• 依托单位: ALBERT EINSTEIN COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-07-01 至 2027-12-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10586498
• 关键词: Adherens Junction; Anatomy; Auditory; Auditory system; Belief; Biological; Cells; Chemical Synapse; Chemicals; Chemosensitization; Communication; Complex; Connexins; Electrical Synapse; Electrophysiology (science); Excision; Exposure to; Family; Fishes; Gap Junctions; Glutamate Receptor; Goals; Hearing problem; Heterozygote; Image; Individual; Investigation; Knowledge; Mediating; Microscopy; Modeling; Modification; Molecular; Mutation; Neurons; Perception; Property; Proteins; Regulation; Research; Role; Scaffolding Protein; Shapes; Signal Transduction; Spatial Distribution; Structural Protein; Structure; Synapses; Synaptic Transmission; Synaptic plasticity; Transgenic Organisms; Zebrafish; auditory pathway; auditory processing; electrical property; gap junction channel; genetic manipulation; in vivo imaging; neural; neuronal circuitry; new therapeutic target; novel; postsynaptic; recruit; scaffold; synaptic function; transmission process

Abstract Electrical synapses, mediated by neuronal gap junctions (GJs), are widespread throughout the auditory pathway. However, the functional roles and properties of electrical synapses in the auditory system remain poorly understood. Our proposal aims to contribute to a better understanding of the properties of electrical synaptic transmission in the auditory system by investigating the molecular mechanisms responsible for plastic changes of electrical transmission at ‘mixed’, electrical and chemical, synaptic contacts that couple primary auditory afferents to the Mauthner (M-) cells in fish. Facilitated by their unique experimental accessibility, our previous investigations revealed that electrical (and chemical) transmission at these mixed synapses undergo activity- dependent synaptic potentiation. There is a prevailing perception that modifications of electrical transmission only result from direct modification of the properties of already existing GJ channels. This interpretation results from the narrow belief that electrical synapses represent simple clusters of intercellular channels. However, rather than fixed, GJs are quite dynamic structures at which channels turn over to maintain their strength at rates comparable to those of glutamate receptors in chemical synapses. Accordingly, our progress indicates that regulated insertion and removal of GJ channels governed by a molecular scaffold critically contributes to regulate electrical synapses. We found that the function of ZO-1, a postsynaptic scaffolding protein, is required for the presence of connexins (the channel-forming proteins). This finding represents a paradigm shift in the understanding of the molecular mechanisms underlying electrical transmission by demonstrating the hierarchy of associated intracellular scaffolding proteins over channel-forming proteins. Furthermore, while electrical transmission is generally thought to occur from single canonical oval-shaped GJ plaques, our preliminary results show that an electrical synapse operates with multiple GJs requiring the functional association with additional structures, such as nearby adherens junctions. By taking advantage of the experimental accessibility provided by these auditory mixed synapses and the zebrafish (ZF) model, we propose to expand the molecular, organizational, and functional framework of the electrical synapse, to encompass the complexity required to support plastic changes of function. Our approach provides a powerful window for the analysis of electrical transmission at which detailed molecular mechanisms will be investigated by combining in-vivo imaging of transgenic fish at which GJ proteins are tagged with fluorescent proteins, electrophysiology and detailed anatomical analysis using expansion microscopy with powerful genetic manipulations. Aim 1, is to determine the role of ZO-1 in mediating plasticity of electrical transmission. Aim 2, is to investigate the functional contribution of additional scaffold components to plastic changes of electrical transmission. Aim 3, is to expose the components and anatomical organization of an electrical synapse. In particular, the aim will explore the anatomical and functional relationship between GJs and adherens junctions, which evidence suggests promotes the insertion of new GJ channels, therefore suggesting a potential role in synaptic transmission and its plasticity. The description of novel molecular mechanisms involved in their regulation will contribute to a better understanding of the dynamics of circuits relevant to auditory dysfunction and the potential identification of novel therapeutic targets.

摘要 由神经元缝隙连接（GJs）介导的电突触广泛存在于整个听觉通路中。 然而，电突触在听觉系统中的功能作用和特性仍然很差 明白我们的建议旨在有助于更好地了解电突触的性质， 通过研究负责可塑性变化的分子机制， 电传输的“混合”，电和化学，突触接触，耦合初级听觉 毛特纳（M-）细胞在鱼的传入。由于其独特的实验性可访问性，我们以前的 研究表明，这些混合突触的电（和化学）传递经历了活动， 依赖性突触增强有一种普遍的看法，即修改电力传输 仅由直接修改已经存在的GJ信道的属性产生。这种解释导致 从狭隘的信念，即电突触代表简单的集群细胞间通道。然而，在这方面， GJ不是固定的，而是一种动态的结构，在这种结构中，通道可以通过转换来保持其强度 与化学突触中谷氨酸受体的相似。因此，我们的进展表明， 由分子支架控制的GJ通道的调节插入和去除关键地有助于调节 电突触我们发现，ZO-1的功能，突触后支架蛋白，是所需的， 连接蛋白（通道形成蛋白）的存在。这一发现代表了一种范式转变， 通过展示层次结构来理解电传输的分子机制 相关的细胞内支架蛋白超过通道形成蛋白。此外，虽然电 我们的初步研究结果表明，一般认为传播发生在单个典型的椭圆形GJ斑块上， 表明电突触与多个GJ一起工作，需要与附加的功能关联， 结构，例如附近的粘附连接。通过利用提供的实验可访问性， 通过这些听觉混合突触和斑马鱼（ZF）模型，我们建议扩展分子， 组织和功能框架的电突触，以涵盖所需的复杂性， 支持塑料功能的变化。我们的方法提供了一个强大的窗口，分析电气 将通过结合体内成像来研究详细的分子机制， 用荧光蛋白标记GJ蛋白的转基因鱼，电生理学和详细的 使用具有强大遗传操作的扩展显微镜进行解剖分析。目标1：确定 ZO-1在介导电传输可塑性中的作用。目的2，是研究功能贡献 额外的支架组件来改变电力传输。目标3：揭露 电突触的组成和解剖结构。特别是，该目标将探讨 GJ和粘附连接之间的解剖学和功能关系，证据表明促进 新的GJ通道的插入，因此表明在突触传递及其可塑性的潜在作用。 对参与其调节的新分子机制的描述将有助于更好地研究 理解与听觉功能障碍相关的电路的动力学， 治疗目标