Transmitter Release From Mammalian Horizontal Cells.

哺乳动物水平细胞释放发射器。

• 批准号: 7878995
• 负责人: NICHOLAS C. BRECHA
• 金额: $ 15.87万
• 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 2010-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7878995
• 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（申请人提供）：光感受器突触三联体由光感受器末端、双极细胞树突和水平细胞末端组成，是一种非常重要的特殊突触复合体。从生理学角度来说，这是光感受器视觉信息最初传输的场所，信息传输的保真度对于视觉处理至关重要。水平细胞介导外视网膜双极细胞树突和光感受器末端的抑制反馈；然而，人们对哺乳动物水平细胞释放递质的机制知之甚少。例如，突触三联体中的水平细胞末端具有相对较少的小而透明的核心囊泡，并且它们缺乏传统定义的突触前膜特化。相反，这些细胞表达已建立的突触小泡蛋白，包括囊泡 GABA 转运蛋白 (VGAT) 和 SV2A，突触蛋白的补充，包括 SNAP-25 和复合蛋白，与胞吐作用和 L 型 Ca2+ 通道相关，表明 GABA通过囊泡机制释放。该机制不同于先前为非哺乳动物水平细胞描述的 GABA 质膜转运机制。 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。本申请将通过检查哺乳动物水平细胞中存在介导囊泡递质释放的细胞结构和生化机制的假设来实现这一目标。该假设将按如下方式进行检验： 具体目标 1：表征突触三联体中水平细胞末端的囊泡。将用传统电子显微镜检查支配锥蒂的水平细胞树突和支配杆小球的轴突末端的囊泡类型、数量和分布。具体目标 2：通过确定 a) VGAT 和 b) VAMP 同工型、SV2A、突触结合蛋白 1 和 2、Rab3 同工型和空泡质子的表达，检查参与水平细胞末端受调节胞吐作用的主要囊泡蛋白的分布RT-PCR 和免疫组织化学泵。具体目标 3：通过测定突触蛋白、SNAP-25 和复合蛋白 1-4、Munc 13-1 的表达，检查水平细胞末梢中参与调节递质释放的囊泡对接、启动和融合的关键突触蛋白的分布和 18，以及 RIM1，采用 RT-PCR 和免疫组织化学。 这些研究将进一步阐明水平细胞释放递质的结构和生化基础，从而更好地了解视网膜外层水平细胞的功能作用。这些发现将有助于制定治疗策略，用于治疗与视网膜疾病相关的外视网膜病理变化，例如黄斑变性。