Transmitter Release From Mammalian Horizontal Cells.

哺乳动物水平细胞释放发射器。

• 批准号: 8145055
• 负责人: NICHOLAS C. BRECHA
• 金额: $ 7.17万
• 依托单位: UNIVERSITY OF CALIFORNIA LOS ANGELES
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-08-01 至 2011-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8145055
• 关键词: Accounting; Address; Biochemical; Biological Models; Cell physiology; Cells; Cellular Structures; Color; Complement; Complex; Comprehension; Confocal Microscopy; Dendrites; Desmosomes; Docking; Electron Microscopy; Exocytosis; Feedback; Figs - dietary; Foundations; Glutamates; Goals; Immunohistochemistry; Knowledge; Light Adaptations; Macular degeneration; Mediating; Membrane; Membrane Proteins; Membrane Transport Proteins; Modeling; Molecular; Morphology; Mus; Oryctolagus cuniculus; Photoreceptors; Physiological; Presynaptic Terminals; Property; Protein Isoforms; Proteins; Proton Pump; Reporting; Research Personnel; Retina; Retinal; Retinal Cone; Retinal Diseases; Reverse Transcriptase Polymerase Chain Reaction; Role; SNAP receptor; Signal Transduction; Site; Synapses; Synaptic Transmission; Synaptic Vesicles; Triad Acrylic Resin; Vesicle; Visual; base; gamma-Aminobutyric Acid; ganglion cell; horizontal cell; information processing; luminance; postsynaptic; presynaptic; programs; research study; response; retinal rods; ribbon synapse; synaptotagmin I; syntaxin; syntaxin 1; therapeutic development; treatment strategy; uptake; vesicular GABA transporter; visual information; visual process; visual processing

DESCRIPTION (provided by applicant): The photoreceptor synaptic triad, consisting of a photoreceptor terminal, bipolar cell dendrites and horizontal cell endings, is a specialized synaptic complex of great importance. Physiologically, this is the site of initial transfer of visual information from photoreceptors and the fidelity of information transfer is critically important for visual processing. Horizontal cells mediate inhibitory feedback in the outer retina at bipolar cell dendrites and photoreceptor terminals; however, the mechanisms that underlie transmitter release from mammalian horizontal cells are poorly understood. For instance, horizontal cell endings in the synaptic triad have relatively few small, clear-core vesicles and they lack conventionally defined presynaptic membrane specializations. In contrast, these cells express established synaptic vesicle proteins, including the vesicular GABA transporter (VGAT) and SV2A, a complement of synaptic proteins, including SNAP-25 and complexin, that are associated with exocytosis, and L-type Ca2+ channels, suggesting GABA is released by a vesicular mechanism. This mechanism differs from a previously established GABA plasmalemmal transporter mechanism described for non-mammalian horizontal cells. The long-term objective of this project is to understand the functional role of mammalian horizontal cells in visual information processing. This application will address this objective by examining the hypothesis that the cellular structure and biochemical machinery that mediate vesicular transmitter release are present in mammalian horizontal cells. This hypothesis will be examined as follows: Specific aim 1: Characterize vesicles in horizontal cell endings in the synaptic triad. Vesicle type, number and distribution in horizontal cell dendrites that innervate cone pedicles and axonal terminals that innervate rod spherules will be examined with conventional electron microscopy. Specific aim 2: Examine the distribution of the principal vesicular proteins which are involved in regulated exocytosis in horizontal cell endings by determining the expression of a) VGAT and b) VAMP isoforms, SV2A, synaptotagmin 1 and 2, Rab3 isoforms, and the vacuolar proton pump with RT-PCR and immunohistochemistry. Specific aim 3: Examine the distribution of key synaptic proteins, which participate in vesicle docking, priming and fusion in regulated transmitter release, in horizontal cell endings by determining the expression of syntaxin, SNAP-25 and complexin 1-4, Munc 13-1 and 18, and RIM1 with RT-PCR and immunohistochemistry. These studies will further elucidate the structural and biochemical basis of transmitter release from horizontal cells, thus providing a better understanding of the functional role of horizontal cells in the outer retina. These findings will aid in the development of therapeutic strategies for the treatment of pathological changes in the outer retina related to retinal disease, such as macular degeneration.

描述（由申请人提供）：光感受器突触三合会，由光感受器末端，双极细胞树突和水平细胞末端组成，是一种非常重要的专业突触复合体。从生理上讲，这是从光感受器初始传输视觉信息的位置，信息传递的保真度对于视觉处理至关重要。水平细胞介导双极细胞树突和光感受器末端的视网膜外视网膜中的抑制反馈；但是，从哺乳动物水平细胞中释放发射机的机制知之甚少。例如，突触三合会中的水平细胞末端具有相对较小的透明囊泡，并且缺乏常规定义的突触前膜的特殊性。相反，这些细胞表达建立的突触囊泡蛋白，包括囊泡GABA转运蛋白（VGAT）和SV2A，包括SNAP-25和复合蛋白在内的突触蛋白的补充，这些补体与胞外胞胞菌病有关，与L型Ca2+通道相关，建议通过vesicular机制释放了L型Ca2+通道。该机制与对非哺乳动物水平细胞的先前建立的GABA血浆转运蛋白机制有所不同。 该项目的长期目标是了解哺乳动物水平细胞在视觉信息处理中的功能作用。该应用将通过检查哺乳动物水平细胞中存在介导水囊发射机释放的细胞结构和生化机制的假设来解决这一目标。该假设将如下检查：特定目标1：表征突触三合会水平细胞末端中的囊泡。将使用传统的电子显微镜检查支配锥形圆锥椎弓根和轴突末端的水平细胞树突中的囊泡类型，数量和分布。具体目的2：通过确定a）VGAT和b）VAMP亚型，SV2A，SV2A，SynaptoTagmin 1和2，Rab3同种型以及液泡质子泵与RT-PCR-PCR-PCR-PCR-PCR-PCR和Immignunoy Ornemys Chormantosistossrymistr和Immunyoystrymistersistr和Immumunoy Orstomistrys的表达来检查水平细胞末端调节胞吐作用的分布，这些分布涉及水平细胞末端的调节胞吞作用。具体目的3：检查关键突触蛋白的分布，这些蛋白在调节的发射机释放中参与囊泡对接，启动和融合，在水平细胞终止中，通过确定索法素的表达，SNAP-25和Conffferin 1-4，MUNCS 13-1和18-1和18，以及用RT-PCR和Immunoe组织的RIM1的表达。 这些研究将进一步阐明从水平细胞释放发射机的结构和生化基础，从而更好地了解水平细胞在外视网膜中的功能作用。这些发现将有助于制定治疗与视网膜疾病相关的视网膜病理变化的治疗策略，例如黄斑变性。