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）：通过不断释放谷氨酸囊泡的变化，光感受器的光反应在视网膜的第一个突触中传播。 AIM 1提议确定限制在光与黑暗中从锥体中释放的速率的机制。连续释放的限速步骤依赖钙依赖性，因此通过钙进入的电压依赖性变化释放膜电位的光诱发变化。建模，成像和电生理学将用于检验以下假设：钙调蛋白和钙调蛋白激酶II的作用通过加速突触囊泡的分子启动或增强色带活性区域的囊泡附着来调节持续释放。实验还测试了持续释放速率是否可能受到释放位点功能状态后可以在Prio囊泡融合事件发生后恢复的速率的限制。先前发布可能限制后续发布位点功能的一种方法是破坏钙通道和释放位点之间的紧密空间关系。与仅在功能区活跃区域释放的锥体不同，从杆上的大部分缓慢持续释放都发生在活性区外的异位部位。这种异位的非核心释放是由存储在内质网中的钙的释放驱动的。 AIM 2检验了以下假设：钙从内质网中持续释放从黑暗中的杆从杆上释放出突触释放，并且从细胞内存储中的这种释放是由于钙离子通过钙离子通过内质网的连续隧穿而维持的。圆锥体具有多达50个带状的活动区域。 AIM 3询问锥体中单个丝带的钙变化的电压依赖性不同，从而促进突触异质性，或者它们是否像单个分布式色带一样工作。总之，这些实验旨在确定在视网膜第一次突触中塑造视力的关键过程，对于理解突触活动中与疾病相关的变化的后果以及通过治疗干预恢复正常的视觉功能至关重要。