Dynamics of calcium signals control neurotransmitter release in retinal ribbon synapses

钙信号的动力学控制视网膜带突触中神经递质的释放

• 批准号: 10540733
• 负责人: Thirumalini Vaithianathan
• 金额: $ 38万
• 依托单位: UNIVERSITY OF TENNESSEE HEALTH SCI CTR
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-01-01 至 2025-12-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10540733
• 关键词: Address; Adult; Biological Models; Biology; Calcium Signaling; Cells; Central Nervous System; Communication; Complex; Computer Models; Data; Defect; Development; Diabetic Neuropathies; Disease; Electron Microscopy; Electrophysiology (science); Future; Glaucoma; Goals; Health system; Homeostasis; Human; Individual; Investigation; Kinetics; Knowledge; Laboratories; Measures; Mission; Molecular; Molecular Target; Monitor; Nerve Degeneration; Neurons; Neurotransmitters; Organelles; Physiological; Process; Property; Proteins; Public Health; Regulation; Research; Retina; Retinal Degeneration; Retinal Diseases; Rod; Role; Sensory; Signal Transduction; Site; Speed; Stimulus; Synapses; Synaptic Transmission; Synaptic Vesicles; Techniques; Testing; Therapeutic Intervention; United States National Institutes of Health; Vesicle; Vision; Visual System; age related; analog; cytomatrix; diabetic; disability; fluorescence imaging; luminance; millisecond; neurotransmission; neurotransmitter release; novel; optic nerve disorder; pharmacologic; prevent; programs; rate of change; recruit; ribbon synapse; segregation; spatiotemporal; stem; therapeutic development; tool; transmission process; visual control; visual information; visual stimulus; voltage clamp

Retinal bipolar cells are the first 'projection neurons' of the vertebrate visual system and transmit all of the information needed for vision. Bipolar cells can signal change in contrast while providing an analog read-out of luminance via changing the rate of neurotransmitter release (NTR). To maintain this ability, the bipolar cells must have dynamic control over release rate and the efficient recruitment of release-ready vesicles to fusion sites. However, the spatiotemporal properties of Ca2+ signals that control NTR, and the molecular entities that control the interplay between Ca2+ signal and vesicle dynamics in sustaining kinetically distinct NTR components remain poorly understood. The long-term goal is to unveil the regulation of Ca2+ signaling in retinal ribbon synapses during development, normal adulthood, and disease. Within this goal, the overall objective of this proposal is to determine the spatiotemporal properties of Ca2+ signals that control kinetically distinct pools of NTR and the role of local Ca2+ signals in governing vesicle dynamics that sustain neurotransmission in bipolar cell ribbon synapses. The central hypothesis is that Ca2+ domains governing kinetically distinct components of NTR are different because the ribbon itself adds an additional compartment responsible for spatial segregation of kinetically different synaptic vesicles and the underlying molecular targets that sense Ca2+ concentration and/or alter Ca2+ signals. This hypothesis is based on preliminary data, acquired in applicant’s laboratory using novel techniques developed for evaluating the traffic of single synaptic vesicles at ribbons while simultaneously measuring the underlying changes in [Ca2+], all with millisecond temporal precision. This hypothesis will be tested by pursuing two specific aims using a confluence of state-of-the-art fluorescence imaging, voltage-clamp electrophysiology, computational modeling, electron microscopy of individual physiologically identified cells, and pharmacological tools: 1) Reveal the mechanisms that determine the spatiotemporal properties of calcium signals which control kinetically distinct neurotransmitter release pools; and 2) Determine the interplay between local calcium signaling and vesicle replenishment that is required for sustaining kinetically distinct components of NTR in rod bipolar cell ribbon synapses as a model system. Dysregulation of Ca2+ signaling is a key early–stage process of neurodegeneration in age-related retinal degenerations, glaucoma, diabetic, and optic neuropathies. The knowledge gained from studying Ca2+ dynamics in bipolar cell synaptic transmission will allow us to determine if defects with local Ca2+ homeostasis are a prelude to disease in the future. Data generated from this proposal will have a broad impact that extends beyond our specific investigation of rod bipolar cells and will be applicable to similar ribbon synapses located within and outside the visual system and encoding distinct aspects of sensory information. More widely, our data will be relevant to synapses throughout the central nervous system because the CAZ of ribbon synapses shares many molecular components with conventional synapses.

视网膜双极细胞是脊椎动物视觉系统的第一个“投射神经元”，并传输所有信息 视觉所需的信息。双极电池可以发出对比度变化信号，同时提供模拟读数 通过改变神经递质释放（NTR）的速率来调节亮度。为了保持这种能力，双极细胞 必须动态控制释放速率和有效招募准备释放的囊泡以进行融合 网站。然而，控制 NTR 的 Ca2+ 信号的时空特性以及控制 NTR 的分子实体 控制 Ca2+ 信号和囊泡动力学之间的相互作用，以维持动力学上不同的 NTR 的组成部分仍然知之甚少。长期目标是揭示视网膜中 Ca2+ 信号传导的调控 发育、正常成年期和疾病期间的带状突触。在此目标下，总体目标是 该提案旨在确定控制动力学不同池的 Ca2+ 信号的时空特性 NTR 的作用以及局部 Ca2+ 信号在控制维持神经传递的囊泡动力学中的作用 双极细胞带状突触。中心假设是 Ca2+ 域控制着不同的动力学 NTR 的组件有所不同，因为丝带本身增加了一个额外的隔间，负责 动力学不同的突触小泡的空间分离和感知的潜在分子靶标 Ca2+ 浓度和/或改变 Ca2+ 信号。这个假设是基于初步数据，获得于 申请人的实验室使用为评估单个突触小泡的交通而开发的新技术 色带，同时测量 [Ca2+] 的潜在变化，所有这些都在毫秒时间内完成 精确。该假设将通过使用最先进的技术的融合来追求两个特定目标来检验 荧光成像、电压钳电生理学、计算建模、电子显微镜 个体生理学鉴定的细胞和药理学工具：1）揭示决定的机制 控制动力学上不同的神经递质释放的钙信号的时空特性 水池； 2) 确定局部钙信号传导和囊泡补充之间的相互作用 作为模型，维持杆状双极细胞带状突触中 NTR 的动力学不同成分所需 系统。 Ca2+信号传导失调是年龄相关神经退行性变的关键早期过程 视网膜变性、青光眼、糖尿病和视神经病变。研究Ca2+所获得的知识 双极细胞突触传递的动力学将使我们能够确定局部 Ca2+ 稳态是否存在缺陷 是未来疾病的前奏。该提案产生的数据将产生广泛的影响 超出了我们对杆状双极细胞的具体研究，并将适用于位于类似带状突触 视觉系统内外并对感官信息的不同方面进行编码。更广泛地说，我们的 数据将与整个中枢神经系统的突触相关，因为带状突触的 CAZ 与传统突触共享许多分子成分。