Transmitter Release from Mammalian Horizontal Cells

哺乳动物水平细胞的发射器释放

• 批准号: 8235389
• 负责人: NICHOLAS C. BRECHA
• 金额: $ 50.69万
• 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 2016-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8235389
• 关键词: Address; Aminobutyric Acids; Autocrine Communication; Binding; Blindness; Cell membrane; Cell physiology; Cells; Color; Complex; Dendrites; Exocytosis; Extracellular Space; Eye Injuries; Eye diseases; Feedback; Figs - dietary; GABA transporter; Generations; Goals; Health; Image; Light; Light Adaptations; Mediating; Membrane Proteins; Molecular; National Eye Institute; Neurons; Output; Photoreceptors; Play; Presynaptic Terminals; Prevention; Process; Property; Proteins; Proton Pump; Protons; Regulation; Retina; Retinal; Retinal Cone; Retinal Diseases; Role; SNAP receptor; Signal Transduction; Site; Synapses; Synaptic Vesicles; Testing; Triad Acrylic Resin; Vesicle; Visual; autocrine; base; cellular imaging; extracellular; feeding; gamma-Aminobutyric Acid; horizontal cell; information processing; neurotransmission; novel; programs; receptive field; research study; response; retinal neuron; retinal rods; syntaxin 1A; therapeutic development; treatment strategy; vacuolar H+-ATPase; vesicular SNARE proteins; visual information; visual process; visual processing; voltage

DESCRIPTION (provided by applicant): The photoreceptor synapse triad is a synaptic complex of great importance; physiologically, this is the site of the initial transfer of visual information, and the fidelity of information transfer is critically important for visual processing. The synaptic triad is characterized by the photoreceptor terminal, ON-bipolar cell dendrite and laterally distributed horizontal cell processes. Horizontal cells play a central role in generating the inhibitory receptive-field surrounds of photoreceptors and bipolar cells, as well as other, downstream retinal neurons. Horizontal cells participate in light adaptation, formation of center-surround receptive fields and generation of color opponency in retinal neurons. Vesicular-mediated transmitter release and proton secretion are leading candidates underlying horizontal cell output in the outer retina, although the cellular mechanisms and their sites of action are not yet fully understood. The long-term objective of this program is to understand the role of mammalian horizontal cells in visual information processing. This objective will be addressed by testing the hypotheses that 1) a regulated vesicular mechanism underlies GABA release and proton secretion from horizontal cell processes and their endings, and 2) horizontal cells participate in a pH-sensitive action on photoreceptors via V- ATPase, and an inhibitory GABA action on horizontal and bipolar cells. Specific aim 1 will test if a) vesicle fusion with the plasma membrane is Ca2+-dependent, and determine the b) cellular localization and functional properties of the Ca2+ channel subtypes mediating Ca2+ signaling in horizontal cells. Specific aim 2 will test if a) vesicle fusion with the plasma membrane is SNARE-protein dependent, and determine the b) cellular localization and binding partners of key vesicular and SNARE proteins mediating vesicle exocytosis, including V-ATPase, in horizontal cells. Specific aim 3 will test if horizontal cell vesicular exocytosis mediates a) a pH-sensitive action on photoreceptors via V-ATPase insertion into the synaptic vesicle and plasma membrane and b) GABA action at horizontal and bipolar cells. Experiments will a) evaluate V-ATPase activity in horizontal cell endings, b) determine if pH-sensitive horizontal cell action is mediated by V-ATPase dependent protons and/or other pH-regulating membrane proteins and c) determine if GABA mediates horizontal cell autocrine and bipolar cell feed forward action. Studies using morphological, electrophysiological and cellular imaging approaches will initially elucidate the molecular and cellular basis of regulated vesicular release and proton secretion from horizontal cells, and will determine horizontal cell action on the response properties of outer retinal neurons. Relevance these studies will further the understanding of the cellular mechanisms underlying visual processing in the outer retina, which will aid in the development of therapeutic strategies for the treatment of eye disease and injury. These objectives are consistent with the health-related goals of the National Eye Institute for the development of therapeutic approaches for the treatment and prevention of retinal disease. PUBLIC HEALTH RELEVANCE: Horizontal cells modulate the transfer of visual information in the outer retina from photoreceptors to second order retinal neurons in a process that is critically important for optimizing visual image formation under a broad range of ambient conditions, but our understanding of this process is incomplete and it appears to combine conventional and novel cellular mechanisms. Findings from the proposed studies will provide new and fundamental information concerning the regulation of horizontal cell synaptic signaling via transmitter exocytosis and proton secretion, and will increase our understanding of the molecular and cellular mechanisms underlying light adaptive processes and receptive field formation in the retina. This information is prerequisite for the understanding of normal retinal function and for developing retinal therapies to save or restore vision loss due to outer retina disease.

描述（由申请人提供）：光感受器突触三联体是非常重要的突触复合体；从生理上讲，这是视觉信息最初传递的场所，信息传递的保真度对于视觉处理至关重要。突触三联体的特征是光感受器末端、ON-双极细胞树突和横向分布的水平细胞突起。水平细胞在产生光感受器和双极细胞以及其他下游视网膜神经元的抑制性感受野周围发挥着核心作用。水平细胞参与光适应、中心-周围感受野的形成以及视网膜神经元颜色对抗的产生。囊泡介导的递质释放和质子分泌是外视网膜水平细胞输出的主要候选者，尽管细胞机制及其作用位点尚未完全了解。该计划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作用。该目标将通过测试以下假设来实现：1) 受调节的囊泡机制是水平细胞过程及其末端的 GABA 释放和质子分泌的基础，2) 水平细胞通过 V-ATP 酶参与光感受器的 pH 敏感作用，以及对水平和双极细胞的抑制性 GABA 作用。具体目标 1 将测试 a) 囊泡与质膜的融合是否是 Ca2+ 依赖性的，并确定 b) 水平细胞中介导 Ca2+ 信号传导的 Ca2+ 通道亚型的细胞定位和功能特性。具体目标 2 将测试 a) 囊泡与质膜的融合是否依赖于 SNARE 蛋白，并确定 b) 水平细胞中介导囊泡胞吐作用的关键囊泡和 SNARE 蛋白（包括 V-ATP 酶）的细胞定位和结合伴侣。具体目标 3 将测试水平细胞囊泡胞吐作用是否介导 a) 通过 V-ATP 酶插入突触囊泡和质膜对光感受器的 pH 敏感作用，以及 b) 对水平和双极细胞的 GABA 作用。实验将 a) 评估水平细胞末端的 V-ATP 酶活性，b) 确定 pH 敏感的水平细胞作用是否由 V-ATP 酶依赖性质子和/或其他 pH 调节膜蛋白介导，以及 c) 确定 GABA 是否介导水平细胞自分泌和双极细胞前馈作用。使用形态学、电生理学和细胞成像方法的研究将初步阐明水平细胞调节囊泡释放和质子分泌的分子和细胞基础，并将确定水平细胞对视网膜外神经元反应特性的作用。这些研究的相关性将进一步了解外视网膜视觉处理的细胞机制，这将有助于制定治疗眼部疾病和损伤的治疗策略。这些目标与国家眼科研究所开发治疗和预防视网膜疾病的治疗方法的健康相关目标一致。 公共健康相关性：水平细胞调节外视网膜中视觉信息从光感受器到二阶视网膜神经元的传递，这一过程对于在广泛的环境条件下优化视觉图像形成至关重要，但我们对此过程的理解是不完整，它似乎结合了传统和新颖的细胞机制。拟议研究的结果将提供有关通过递质胞吐作用和质子分泌调节水平细胞突触信号传导的新的基本信息，并将增加我们对视网膜光适应过程和感受野形成背后的分子和细胞机制的理解。这些信息是了解正常视网膜功能和开发视网膜疗法以挽救或恢复因外视网膜疾病引起的视力丧失的先决条件。