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;生理上，这是视觉信息的初始传递部位，并且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感光末梢、ON-双极细胞树突和侧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场周围中起核心作用。水平细胞参与视网膜神经元的光适应、中心-周围感受野的形成和色觉的产生。囊泡介导的递质释放和质子分泌是外层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部位尚未完全了解。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作用。这一目标将通过测试以下假设来解决：1）受调节的囊泡机制是水平细胞突起及其末端的GABA释放和质子分泌的基础，以及2）水平细胞通过V-ATP酶参与对光感受器的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Ca 2+依赖性的，并确定B）介导水平细胞中Ca 2+信号传导的Ca 2+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是SNARE蛋白依赖性的，并确定B）介导囊泡胞吐的关键囊泡和SNARE蛋白（包括V-ATP酶）在水平细胞中的细胞定位和结合配偶体。具体目标3将测试水平细胞囊泡胞吐是否介导a）通过V-ATP酶插入突触囊泡和质膜对光感受器的pH敏感作用和B）水平和双极细胞的GABA作用。实验将a）评估水平细胞末端中的V-ATP酶活性，B）确定pH敏感性水平细胞作用是否由V-ATP酶依赖性质子和/或其它pH调节膜蛋白介导，和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从水平细胞调节囊泡释放和质子分泌的分子和细胞基础，并将确定水平细胞作用于视网膜外神经元的响应特性。相关性这些研究将进一步了解外层视网膜视觉处理的细胞机制，这将有助于开发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的健康相关目标一致，即开发治疗和预防视网膜疾病的治疗方法。 公共卫生关系：水平细胞调节外视网膜中视觉信息从光感受器到二级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，但我们对这一过程的理解是不完整的，它似乎结合了联合收割机常规和新颖的细胞机制。从拟议的研究结果将提供新的和基本的信息，通过递质胞吐和质子分泌水平细胞突触信号的调节，并将增加我们的光适应过程和视网膜感受野形成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治疗以挽救或恢复由于外层视网膜疾病引起的视力丧失的先决条件。