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“投影神经元”，并传输所有 视力所需的信息。双极单元可能会发出对比的信号变化，同时提供了一个模拟读数的模拟 通过改变神经递质释放速率（NTR）的亮度。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，并有效募集释放蔬菜融合 站点。但是，控制NTR的Ca2+信号的时空特性，以及分子实体 控制Ca2+信号与囊泡动力学之间的相互作用，以维持动力学不同的NTR 组件仍然很少了解。长期目标是揭示残差中Ca2+信号的调节 发育过程中的色带突触，正常的成年和疾病。在这个目标中，总体目标 该建议是确定控制动力学不同池的Ca2+信号的时空特性 NTR以及本地CA2+信号在管理蔬菜动态中的作用，以维持神经传递 双极细胞色带突触。中心假设是Ca2+域的控制在动力学上不同 NTR的组件不同，因为色带本身增加了一个额外的隔间 动力学上不同的突触蔬菜的空间隔离和理解的基础分子靶标 Ca2+浓度和/或更改Ca2+信号。该假设基于初步数据，在 申请人的实验室使用用于评估单个突触蔬菜的交通开发的新技术 丝带同时测量[Ca2+]的潜在变化，所有丝带都以毫秒的临时变化 精确。该假设将通过使用最先进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 个人物理鉴定的细胞和药物工具：1）揭示确定的机制 钙信号的时空特性，该钙信号控制动力学不同的神经递质释放 游泳池； 2）确定局部钙信号传导和囊泡复制性之间的相互作用 在杆双极细胞色带突触中维持NTR的动力学不同成分所必需 系统。 CA2+信号传导失调是与年龄相关的神经退行性的关键早期阶段过程 视网膜变性，青光眼，糖尿病和视神经神经病。从研究Ca2+获得的知识 双极细胞突触传播中的动力学将使我们能够确定是否患有局部Ca2+稳态的缺陷 将来是疾病的前奏。该提案产生的数据将产生广泛的影响，扩展 除了我们对杆双极细胞的具体研究，还将适用于相似的色带突触 视觉系统内外，并编码感官信息的不同方面。更广泛，我们的 数据将与整个中枢神经系统中的突触有关，因为色带突触的CAZ 与常规突触共享许多分子成分。