Mechanisms for somatodendritic dopamine release in the midbrain

中脑体细胞树突多巴胺释放机制

• 批准号: 10604832
• 负责人: Pascal Simon Kaeser
• 金额: $ 59.86万
• 依托单位: HARVARD MEDICAL SCHOOL
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-03-15 至 2027-12-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10604832
• 关键词: Ablation; Affect; Architecture; Axon; Behavior; Brain; Brain Diseases; Cells; Characteristics; Cognition; Collection; Complement; Data; Defect; Dendrites; Development; Disease; Dopamine; Drug Addiction; Electrophysiology (science); Emotions; Exocytosis; G-Protein-Coupled Receptors; Glutamates; Goals; Hot Spot; Image; Kinetics; Knockout Mice; Knowledge; Laboratories; Location; Mediating; Membrane; Midbrain structure; Modeling; Molecular; Movement; Mus; Mutant Strains Mice; Nerve; Neuromodulator; Neurons; Neuropeptides; Parkinson Disease; Pathway interactions; Phenotype; Protein Family; Proteins; Receptor Activation; Regulation; Role; Scaffolding Protein; Signal Transduction; Site; Source; Specific qualifier value; Speed; Synapses; Testing; Vesicle; Work; conditional knockout; dopaminergic neuron; drug of abuse; gamma-Aminobutyric Acid; in vivo; knockout gene; monoamine; motor control; mouse genetics; mutant; neuronal excitability; neuropsychiatric disorder; neuroregulation; neurotransmitter release; neurotrophic factor; response; scaffold; secretory protein; sensor; spatiotemporal; superresolution microscopy; synaptotagmin I; tool; transmission process

Summary Many central neurons release neuromodulatory transmitters, for example monoamines, neuropeptides, and neurotrophins, from their somata and dendrites. Release of these transmitters is followed by G-protein coupled receptor activation, and these neuromodulator pathways are essential for brain development and function. Dopamine signaling in the ventral midbrain is a prominent example of this transmission mode, and it is particularly important for the response to drugs of abuse. The knowledge of somatodendritic release and G-protein coupled receptor-mediated transmission lags far behind that of synaptic signaling, but it is often considered slow and imprecise. The long-term goal of this project is to determine the molecular mechanisms that mediate somatodendritic dopamine transmission. We hypothesize that somatodendritic dopamine secretion is mediated by mechanistically specialized machinery for fast and synchronous release. We propose that this machinery is assembled into release hotspots to generate a signal with rapid kinetics that is directed towards G-protein coupled receptor domains on target cells, an architecture ideally suited for robust receptor activation. Our recent work has made first progress towards this goal. We have found that RIM, a protein important for the spatiotemporal precision of axonal transmitter release, is essential for evoked somatodendritic dopamine release. Furthermore, we found that synaptotagmin-1, a fast Ca2+ sensor, mediates Ca2+-triggering of this form of release. We here propose to determine the organization and function of somatodendritic dopamine release machinery using conditional mouse gene knockout, electrophysiology, imaging and superresolution microscopy. In aim 1, we propose to dissect somatodendritic release site architecture in midbrain dopamine neurons. We will systematically test the necessity and localization of five key active zone protein families that control speed and location of exocytosis at classical synapses. In aim 2, we propose to identify Ca2+ sources and sensors for somatodendritic dopamine release. We will assess conditional mouse mutants that lack Ca2+ channel or Ca2+ sensor proteins for secretory deficits and will assess the localization of the proteins needed for Ca2+-triggering in the somatodendritic compartments. These aims will define mechanisms of Ca2+-triggering and are likely to identify active zone-like release hotspots. Our work will further reveal shared and distinct release mechanisms in somatodendritic and axonal compartments of dopamine neurons. This multi-PI project will advance the understanding of somatodendritic dopamine signaling in the midbrain specifically, and of G-protein coupled receptor-mediated transmission in general. It combines the expertise of the laboratories of John Williams and Pascal Kaeser. In-depth studies of these mechanisms will allow us to derive principles and specifications of these neuronal secretory pathways and may ultimately help advancing treatments for diseases with disrupted dopamine function, for example drug addiction.

概括 许多中枢神经元释放神经调节递质，例如单胺、神经肽、 和神经营养素，来自它们的体细胞和树突。这些递质的释放之后是 G 蛋白 耦合受体激活，这些神经调节途径对于大脑发育和 功能。腹侧中脑的多巴胺信号传导是这种传输模式的一个突出例子，它是 对于应对药物滥用尤其重要。 对体细胞树突释放和 G 蛋白偶联受体介导的传播的认识远远滞后 落后于突触信号传导，但通常被认为缓慢且不精确。本次活动的长远目标 该项目的目的是确定介导体树突多巴胺传递的分子机制。 我们假设体树突多巴胺的分泌是由专门的机制介导的 用于快速同步发布。我们建议将这种机器组装到释放热点中以生成 具有快速动力学的信号，针对靶细胞上的 G 蛋白偶联受体结构域， 架构非常适合强大的受体激活。我们最近的工作在这方面取得了初步进展 目标。我们发现 RIM，一种对轴突递质释放的时空精度很重要的蛋白质， 对于诱发体树突多巴胺释放至关重要。此外，我们发现 synaptotagmin-1 是一种快速 Ca2+ 传感器介导 Ca2+ 触发这种形式的释放。 我们在这里建议确定体树突多巴胺释放机制的组织和功能 使用条件小鼠基因敲除、电生理学、成像和超分辨率显微镜。在目标 1 中， 我们建议剖析中脑多巴胺神经元的体树突释放位点结构。我们将 系统地测试控制速度和速度的五个关键活性区蛋白家族的必要性和定位 经典突触胞吐作用的位置。在目标 2 中，我们建议确定 Ca2+ 来源和传感器 体细胞树突多巴胺释放。我们将评估缺乏 Ca2+ 通道或 Ca2+ 的条件小鼠突变体 传感器蛋白分泌缺陷，并将评估 Ca2+ 触发所需蛋白的定位 在体细胞树突室中。这些目标将定义 Ca2+ 触发机制，并可能 识别活跃的类似区域的释放热点。我们的工作将进一步揭示共享和独特的发布机制 在多巴胺神经元的体细胞树突和轴突区室中。 这个多PI项目将促进对中脑体细胞树突多巴胺信号传导的理解 具体而言，以及一般情况下 G 蛋白偶联受体介导的传播。它结合了专业知识 约翰·威廉姆斯和帕斯卡·凯泽的实验室。对这些机制的深入研究将使我们能够 得出这些神经元分泌途径的原理和规范，并可能最终有助于推进 治疗多巴胺功能受损的疾病，例如毒瘾。