Regulation of photoreceptor vesicle resupply and synaptic transfer kinetics

光感受器囊泡补给和突触转移动力学的调节

• 批准号: 8867874
• 负责人: Matthew John Van Hook
• 金额: $ 5.8万
• 依托单位: UNIVERSITY OF NEBRASKA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-07-01 至 2016-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8867874
• 关键词: Acceleration; Attenuated; Auditory; Back; Blindness; Brain; Brain Stem; Buffers; Calcium; Calcium Channel; Calcium/calmodulin-dependent protein kinase; Calmodulin; Cells; Color; Cone; Conscious; Dependence; Disease; Electric Capacitance; Electroretinography; Endocytosis; Eye; Fluorescence Microscopy; Frequencies; Functional disorder; Glutamates; Goals; Health; Image; Imaging Techniques; Individual; Kinetics; Laboratories; Lead; Life; Light; Measurement; Measures; Membrane; Neurons; Neurosciences Research; Peptides; Photons; Photoreceptors; Physiologic pulse; Population; Preparation; Presynaptic Terminals; Process; Property; Proteins; Protocols documentation; Public Health; Quantum Dots; Regulation; Research; Retina; Retinal; Retinal Cone; Retinal Degeneration; Retinal Diseases; Retinal Photoreceptors; Role; Salamander; Shapes; Signal Transduction; Signaling Molecule; Slice; Staging; Stem cells; Stimulus; Structure; Synapses; Synaptic Transmission; Synaptic Vesicles; Techniques; Testing; Therapeutic; Time; Tissues; Training; Vertebrate Photoreceptors; Vesicle; Vision; Visual; Visual Perception; Whole-Cell Recordings; Work; absorption; calmodulin-dependent protein kinase II; luminance; neurotransmission; neurotransmitter release; particle; presynaptic; public health relevance; relating to nervous system; response; retina implantation; retinal neuron; retinal rods; ribbon synapse; trafficking; transmission process; vesicular release; visual process; visual processing; voltage; voltage clamp

DESCRIPTION (provided by applicant): One of the fundamental tasks of basic retina research is to understand how the retina - a thin sheet of light- sensitive tissue at the back of te eye - is responsible for processing and transmitting signals arising from the absorption of photons. This process begins at the very first synapse in the retina, which transmits signals from rod and cone photoreceptors to second-order neurons. The signaling capabilities of photoreceptors depend the synaptic ribbon, a specialized structure found in a variety of neurosensory cells responsible for providing a supply of primed vesicles to support signaling by tonic vesicle release. The objective of this proposal is to explore the fundamental signaling capabilities of the cone ribbon synapse by examining how synaptic ribbons are replenished with vesicles and how that replenishment mechanism contributes to early stages of visual processing in the retina. Previous studies have described the ways in which retinal ribbon synapses are capable of signaling contrast and luminance in a manner dependent on the kinetics of synaptic vesicle replenishment. Recent work in the Thoreson lab has shown that the kinetics of replenishment at the cone ribbon is also accelerated by calcium (Ca2+), pointing to a Ca2+-dependent mechanism for regulating the encoding of photoreceptor signals. At the Calyx of Held, an auditory relay synapse, acceleration of replenishment by calcium depends on the signaling molecule calmodulin. Calmodulin may similarly regulate the Ca2+- dependence of replenishment at photoreceptor synapses, but this possibility has yet to be tested. Aim 1 will test the hypothesis that calmodulin is responsible for a fast, Ca2+-dependent mechanism of vesicle replenishment at the cone ribbon. Additionally, replenishment has been suggested as a major determinant of kinetic-encoding responses by the photoreceptor synapse, yet this also remains untested. Aim 2 will test the hypothesis that a fast calmodulin-dependent mode of replenishment is responsible for encoding and transmitting the timing of visual responses. These goals will be accomplished using a variety of electrophysiological techniques such as electroretinogram and single and paired whole-cell recordings as well as with live imaging techniques such as confocal calcium imaging, TIRF microscopy, and single-particle tracking with quantum dots to assess synaptic signaling by cones. Specific pharmacological compounds, delivered directly to the photoreceptor or applied to the entire retina, will be used to manipulate signaling by calmodulin and Ca2+-dependent processes. Proper encoding and transmission of signals by photoreceptors is crucial to vision. Understanding retinal function in health as well as disease is important when implementing therapeutic approaches that integrate with the existing retinal network such as stem cells or retinal implants. Moreover, an understanding of the mechanisms regulating vesicle resupply and trafficking in photoreceptors, as this proposal seeks to provide, is important in understanding the pathophysiology of several retinal degenerative diseases, as synaptic proteins with roles in the neurotransmission have been implicated in various retinopathies.

描述（由申请人提供）：基础视网膜研究的基本任务之一是了解视网膜-眼睛后部的一薄层光敏组织-如何负责处理和传输由光子吸收产生的信号。这个过程始于视网膜中的第一个突触，它将信号从视杆和视锥光感受器传递到二级神经元。光感受器的信号传导能力取决于突触带，突触带是在多种神经感觉细胞中发现的专门结构，负责提供引发的囊泡的供应以支持通过紧张性囊泡释放的信号传导。这个建议的目的是探索锥带突触的基本信号能力，通过检查突触带是如何补充囊泡和补充机制如何有助于视网膜视觉处理的早期阶段。先前的研究已经描述了视网膜带状突触能够以依赖于突触囊泡补充的动力学的方式发出对比度和亮度信号的方式。Thoreson实验室最近的工作表明，视锥带的补充动力学也被钙（Ca 2+）加速，这表明了一种Ca 2+依赖的调节感光细胞信号编码的机制。在赫尔德花萼（听觉中继突触），钙补充的加速取决于信号分子钙调素。钙调素可能类似地调节光感受器突触的Ca 2+依赖性补充，但这种可能性尚未得到验证。目标1将测试 假设钙调素是负责一个快速，钙离子依赖性机制的囊泡补充在锥带。此外，补充已被认为是一个主要的决定因素的动力学编码反应的感光突触，但这也仍然未经检验。目标2将测试的假设，一个快速钙调素依赖性的补充模式是负责编码和传输的视觉反应的时间。这些目标将使用各种电生理技术，如视网膜电图和单个和成对的全细胞记录，以及与现场成像技术，如共焦钙成像，TIRF显微镜，和单粒子跟踪与量子点，以评估突触信号锥来实现。特定的药理学化合物，直接传递到感光器或应用于整个视网膜，将被用来操纵信号的钙调蛋白和Ca 2+依赖性过程。光感受器对信号的正确编码和传输对视觉至关重要。了解健康和疾病中的视网膜功能是 这在实施与现有视网膜网络（如干细胞或视网膜植入物）整合的治疗方法时很重要。此外，了解调节囊泡再供应和光感受器贩运的机制，如本建议试图提供的那样，对于理解几种视网膜变性疾病的病理生理学是重要的，因为在神经传递中起作用的突触蛋白与各种视网膜病变有关。