Regulation of Photoreceptor Neurotransmission

感光神经传递的调节

• 批准号: 8755176
• 负责人: WALLACE B THORESON
• 金额: $ 38.9万
• 依托单位: UNIVERSITY OF NEBRASKA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-06-01 至 2018-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8755176
• 关键词: Acceleration; Biophysical Process; Ca(2+)-Calmodulin Dependent Protein Kinase; Calcium; Calcium Channel; Calcium ion; Calmodulin; Cells; Computer Simulation; Cone; Confocal Microscopy; Darkness; Dependence; Diffuse; Diffusion; Disease; Docking; Electric Capacitance; Electrophysiology (science); Endocytosis; Endocytosis Inhibition; Endoplasmic Reticulum; Event; Eye; Glutamates; Heterogeneity; Image; Individual; Ions; Ischemia; Label; Light; Link; Location; Macular degeneration; Measurement; Measures; Mediating; Membrane; Membrane Potentials; Microscopy; Modeling; Molecular; Mutation; Neuromodulator; Perikaryon; Photoreceptors; Presynaptic Terminals; Process; Prosthesis; Proteins; Regulation; Retina; Retinal; Shapes; Signal Transduction; Site; Speed; Synapses; Synaptic Vesicles; Techniques; Testing; Therapeutic Intervention; Time; Vertebrate Photoreceptors; Vesicle; Vision; Whole-Cell Recordings; base; design; extracellular; functional status; neuronal cell body; neurotransmission; optogenetics; particle; public health relevance; research study; response; retinal progenitor cell; retinal rods; ribbon synapse; spatial relationship; therapy design; voltage

DESCRIPTION (provided by applicant): Light responses of photoreceptors are transmitted across the first synapse in the retina by changes in the ongoing release of glutamate-filled vesicles. Aim 1 proposes to identify the mechanisms that limit rates of ongoing release from cones in light and dark. The rate-limiting steps in continuous release are calcium-dependent, thus linking light-evoked changes in membrane potential to release rates through voltage-dependent changes in calcium entry. Modeling, imaging, and electrophysiology will be used to test the hypothesis that the actions of calmodulin and calmodulin kinase II regulate sustained release by speeding molecular priming of synaptic vesicles or by enhancing vesicle attachment at the ribbon-style active zone. Experiments also test whether the rate of sustained release may be limited by the rate at which the functional status of release sites can be restored after a prio vesicle fusion event. One way in which prior release might restrict subsequent release site function is by disrupting the close spatial relationship between calcium channels and release sites. Unlike cones where release occurs only at ribbon-style active zones, most of the slow sustained release from rods occurs at ectopic sites outside the active zone. This ectopic, non-ribbon release is driven by release of calcium stored in the endoplasmic reticulum. Aim 2 tests the hypothesis that sustained release of calcium from the endoplasmic reticulum drives synaptic release from rods in darkness and that this release from intracellular stores is sustained by the continuous tunneling of calcium ions through endoplasmic reticulum from perikaryon to synaptic terminal. Cones have as many as 50 ribbon-style active zones apiece. Aim 3 asks whether calcium changes at individual ribbons in a cone differ in their voltage-dependence, thus promoting synaptic heterogeneity, or whether they operate like a single distributed ribbon. Together, these experiments are designed to identify key processes that shape vision at the first synapse in the retina and are essential for understanding the consequences of disease-related changes in synaptic activity as well as for restoring normal visual function by therapeutic interventions.

描述（由申请人提供）：光感受器的光响应通过充满谷氨酸的囊泡持续释放的变化而穿过视网膜中的第一个突触传递。目标 1 提出确定限制锥体在光照和黑暗条件下持续释放速率的机制。连续释放的限速步骤是钙依赖性的，因此通过钙进入的电压依赖性变化将光诱发的膜电位变化与释放速率联系起来。建模、成像和电生理学将用于检验钙调蛋白和钙调蛋白激酶 II 的作用通过加速突触小泡的分子启动或通过增强带状活性区的小泡附着来调节持续释放的假设。实验还测试了持续释放的速率是否可能受到在prio囊泡融合事件后释放位点的功能状态恢复的速率的限制。先前释放可能限制后续释放位点功能的一种方式是破坏钙通道和释放位点之间的紧密空间关系。与锥体释放仅发生在带状活性区不同，杆状体的大部分缓慢持续释放发生在活性区外的异位位点。这种异位、非带状释放是由内质网中储存的钙的释放驱动的。目标 2 测试了这样的假设：内质网中钙的持续释放驱动黑暗中突触从杆中释放，并且细胞内储存的这种释放是通过钙离子通过内质网从核周到突触末端的连续隧道来维持的。每个锥体有多达 50 个带状活动区域。目标 3 询问锥体中各个条带的钙变化是否在电压依赖性方面有所不同，从而促进突触异质性，或者它们是否像单个分布式条带一样运作。这些实验旨在确定视网膜第一个突触形成视觉的关键过程，对于了解疾病相关的突触活动变化的后果以及通过治疗干预恢复正常视觉功能至关重要。