Architecture and Function of Striatal Dopamine Signaling Machinery

纹状体多巴胺信号传导机制的结构和功能

• 批准号: 10589076
• 负责人: Pascal Simon Kaeser
• 金额: $ 54.97万
• 依托单位: HARVARD MEDICAL SCHOOL
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-08-01 至 2027-02-28
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10589076
• 关键词: Ablation; Acetylcholine; Action Potentials; Affinity; Architecture; Axon; Brain; Brain Diseases; Cells; Cellular biology; Cholinergic Receptors; Code; Communication; Corpus striatum structure; Data; Defect; Diffuse; Diffusion; Dopamine; Dopamine D1 Receptor; Dopamine D2 Receptor; Dopamine Receptor; Electrophysiology (science); Endocytosis; Exocytosis; Extracellular Space; Funding; G-Protein-Coupled Receptors; Glutamates; Goals; Image; Interneurons; Laboratories; Lead; Mediating; Membrane; Midbrain structure; Modeling; Molecular; Movement; Mus; Nerve; Nerve Degeneration; Neuromodulator; Neurons; Parkinson Disease; Pathology; Pathway interactions; Phase; Positioning Attribute; Property; Proteins; Receptor Activation; Recycling; Regulation; Role; Signal Transduction; Site; Slice; Speed; Structure; Synapses; Synaptic Cleft; Synaptic Transmission; System; Testing; Three-Dimensional Image; Vesicle; Work; biomarker identification; cholinergic; cholinergic neuron; dopaminergic neuron; experimental study; functional plasticity; insight; knockout gene; meter; millisecond; molecular assembly/self assembly; molecular marker; nanometer; nanoscale; nervous system disorder; neuronal cell body; neuroregulation; neurotransmitter release; presynaptic; receptor; superresolution microscopy; tool; trafficking; transmission process; ultra high resolution; voltage

Summary Dopamine is an important neuromodulator and pathologies in dopamine signaling are a hallmark of brain disease. Despite these roles, the organization and regulation of dopamine signaling are incompletely understood. The long-term goal of this project is to dissect the cell biology of axonal dopamine transmission. Spatial and temporal features of dopamine signaling are different from synaptic transmission. At conventional synapses, nanometer-scale synaptic structure enables robust receptor activation at sub-millisecond speeds and restricts communication to point-to-point contacts between select neurons. In contrast, dopamine is a volume transmitter that diffuses through the extracellular space after exocytosis and may influence many cells through G-protein coupled receptors. These properties suggest that dopamine transmission is slow and diffuse. Recent data from several laboratories, including some generated during the previous funding cycle, however, have revealed that dopamine transmission is highly dynamic and, in some cases, remarkably precise. Furthermore, dopamine release is powerfully and rapidly regulated by local cholinergic interneurons in the striatum. These findings suggest that the coding of dopamine volume transmission is more precise than previously thought. A major question that arises is how the architecture for dopamine transmission can support precise signaling. Our overarching model is that molecular machinery has evolved to support broad dopamine coding scales. We build on our previous findings that axonal dopamine exocytosis is executed with millisecond precision by sparse, sophisticated protein machinery typically present at synapses. In aim 1, we zoom in on the powerful local regulation and ask how cholinergic neurons trigger dopamine release. Based on preliminary data, we hypothesize that activity in cholinergic interneurons induces ectopic action potential firing in dopamine axons to trigger dopamine secretion. Our goal is to test this hypothesis and to understand the underlying mechanisms. Identification of an endogenous mechanism for ectopic axonal action potential initiation away from the dopamine neuron soma has important implications for dopamine neuron function. In aim 2, we dissect the organization of dopamine receptors relative to release sites. We build on recent work that identified markers for these sparse secretory sites. Our preliminary data reveal that dopamine receptors are clustered one to two micrometers away from release sites and suggest differences in D1 vs. D2 receptor distributions. We will systematically assess release-receptor organization in super-resolved 3D-images of large striatal volumes and will mechanistically dissect how it is set up. We propose that the organization is different from nanoscale synaptic structure and from the diffuse organization often associated with volume transmission, and may be suited to mediate distinct pathway activation by switches in dopamine neuron firing modes. Our work will dissect the organization of specialized dopamine signaling architecture and rapid, local triggering mechanisms of dopamine release in the vertebrate striatum.

概括 多巴胺是一种重要的神经调节剂，多巴胺信号传导的病理学是大脑的标志 疾病。尽管具有这些作用，但多巴胺信号传导的组织和调节尚不完全清楚。 该项目的长期目标是剖析轴突多巴胺传递的细胞生物学。 多巴胺信号传导的空间和时间特征不同于突触传递。在常规 突触，纳米级突触结构能够以亚毫秒的速度实现强大的受体激活， 将通信限制为选定神经元之间的点对点接触。相反，多巴胺是一种体积 胞吐作用后通过细胞外空间扩散的递质，可能通过以下方式影响许多细胞 G蛋白偶联受体。这些特性表明多巴胺的传递是缓慢且分散的。最近的 然而，来自多个实验室的数据，包括上一个资助周期中产生的一些数据， 研究表明，多巴胺的传递是高度动态的，并且在某些情况下非常精确。此外， 多巴胺的释放受到纹状体中局部胆碱能中间神经元的有力而快速的调节。这些 研究结果表明，多巴胺容量传输的编码比之前想象的更精确。 出现的一个主要问题是多巴胺传输的架构如何支持精确的 发信号。我们的总体模型是分子机制已经发展到支持广泛的多巴胺编码 秤。我们基于之前的发现，即轴突多巴胺胞吐作用以毫秒精度执行 由通常存在于突触处的稀疏而复杂的蛋白质机制实现。在目标 1 中，我们聚焦于强大的 局部调节并询问胆碱能神经元如何触发多巴胺释放。根据初步数据，我们 假设胆碱能中间神经元的活动诱导多巴胺轴突异位动作电位放电 触发多巴胺分泌。我们的目标是检验这一假设并了解其潜在机制。 鉴定远离多巴胺的异位轴突动作电位起始的内源机制 神经元胞体对多巴胺神经元功能具有重要意义。在目标 2 中，我们剖析组织 多巴胺受体与释放位点的关系。我们以最近确定这些标记的工作为基础 分泌部位稀疏。我们的初步数据显示多巴胺受体聚集一到两微米 远离释放位点并表明 D1 与 D2 受体分布的差异。我们将系统地 评估大纹状体体积的超分辨率 3D 图像中的释放受体组织，并将 机械地剖析它是如何设置的。我们认为该组织不同于纳米级突触 结构和来自通常与体积传输相关的扩散组织，并且可能适合 通过多巴胺神经元放电模式的切换介导不同的通路激活。 我们的工作将剖析专门的多巴胺信号传导架构的组织和快速、局部的 脊椎动物纹状体中多巴胺释放的触发机制。