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: 10320486
• 负责人: Thirumalini Vaithianathan
• 金额: $ 36.86万
• 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/10320486
• 关键词: Address; Adult; Biological Models; Biology; Calcium; Calcium Signaling; Cells; 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; Neuraxis; Neurons; Neurotransmitters; Organelles; Pharmacology; 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 structure; age related; analog; base; cytomatrix; disability; fluorescence imaging; luminance; millisecond; neurotransmission; neurotransmitter release; novel; optic nerve disorder; 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”， 视觉所需的信息。双极单元可以用信号通知对比度的变化，同时提供对比度的模拟读出。 通过改变神经递质释放速率（NTR）来调节亮度。为了维持这种能力，双极细胞 必须对释放速率进行动态控制，并有效募集准备释放的囊泡以进行融合 网站.然而，控制NTR的Ca 2+信号的时空特性，以及控制NTR的分子实体， 控制Ca 2+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 对这些组成部分仍然知之甚少。长期目标是揭示视网膜神经元中Ca 2+信号的调节， 带状突触在发育，正常成年和疾病。在这一目标范围内， 这个建议是确定控制动力学上不同池的Ca 2+信号的时空特性 NTR和局部Ca 2+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，Ca 2+结构域控制动力学上不同的 NTR的组成部分是不同的，因为丝带本身增加了一个额外的隔间，负责 动力学不同的突触囊泡和感知的潜在分子靶点的空间分离 Ca 2+浓度和/或改变Ca 2+信号。这一假设是基于初步数据， 申请人的实验室使用开发用于评估单个突触囊泡的运输的新技术， 同时测量[Ca 2 +]的潜在变化，所有这些都具有毫秒时间 精度这一假设将通过追求两个具体的目标进行测试，使用最先进的融合 荧光成像，电压钳电生理学，计算建模， 个体生理学鉴定的细胞和药理学工具：1）揭示决定 控制动力学上不同的神经递质释放的钙信号的时空特性 2）确定局部钙信号传导和囊泡补充之间的相互作用， 所需的维持动力学不同的组件的NTR在杆双极细胞带状突触作为一个模型 系统Ca 2+信号转导失调是年龄相关性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Ca ~（2+）的认识 双极细胞突触传递的动力学将使我们能够确定局部Ca 2+稳态的缺陷是否 是未来疾病的前奏。本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，并将适用于类似的带状突触， 在视觉系统内部和外部，并编码感官信息的不同方面。更广泛地说，我们 数据将与整个中枢神经系统的突触相关 与传统的突触有许多共同的分子组成部分。