TRP channel expression and function in ON-bipolar cells

ON-双极细胞中 TRP 通道的表达和功能

• 批准号: 8204649
• 负责人: RONALD Lane BROWN
• 金额: $ 44.44万
• 依托单位: OREGON HEALTH & SCIENCE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-01-01 至 2013-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8204649
• 关键词: Affect; Apical; Biochemical; Blindness; Cations; Cells; Complex; Coupled; Darkness; Data; Defect; Dendrites; Disease; Electrophysiology (science); Electroretinography; Equus caballus; Eye; Eye Movements; Eye diseases; Family; GRM6 gene; GTP-Binding Proteins; Gated Ion Channel; Gene Expression Profiling; Genes; Genetic; Glutamate Receptor; Glutamates; Go Alpha Subunit; Goals; Hyperopia; Immunohistochemistry; In Situ Hybridization; In Vitro; Inherited; Ion Channel; Light; Lighting; Macaca; Measures; Mediating; Metabotropic Glutamate Receptors; Molecular; Molecular Genetics; Mus; Mutation; Myopia; Night Blindness; Pathologic Nystagmus; Pathology; Pathway interactions; Pharmacology; Phenotype; Photoreceptors; Physiological; Physiology; Property; RNA Splicing; Reporting; Research; Rest; Retina; Retinal; Retinal Cone; Retinal Diseases; Reverse Transcriptase Polymerase Chain Reaction; Shapes; Signal Pathway; Signal Transduction; Staging; Symptoms; Synapses; Synaptic Transmission; Testing; Variant; Vision; Visual; Visual Acuity; Visual Pathways; Visual system structure; Work; abstracting; base; gene function; image processing; in vivo; insight; light intensity; member; mouse model; mutant; null mutation; patch clamp; postsynaptic; receptor; response; retinal rods; visual information; visual process; visual processing

Project Summary/Abstract Congenital stationary night blindness (CSNB) is a group of non-progressive retinal diseases characterized by impaired scotopic vision. Mutations in a number of genes have been shown to be associated with CSNB. They generally affect synaptic transmission between photoreceptors and the second order bipolar cells. When the mutant gene is expressed only in rods, or rod bipolar cells, the phenotype is limited to night blindness. However, when the mutant gene function is also required for synaptic transmission between cones and cone bipolar cells, further visual symptoms are apparent such as myopia, hyperopia, nystagmus, and reduced visual acuity. One such example are mutations in GRM6, the gene encoding mGluR6, which cause an autosomal recessive form of CSNB. In the retina, visual information is segregated into pathways that respond to increases and decreases in light intensity. At the first retinal synapse, the tonic release of glutamate from photoreceptor terminals maintains a high synaptic concentration in darkness that decreases in response to light. Two types of postsynaptic cells, the ON- and OFF-bipolar cells, respond with opposite polarity to glutamate released by photoreceptors, thus establishing the opposing visual pathways. The basis of signaling in OFF-bipolar cells, which relies on the activation of ionotropic glutamate receptors, is well understood. The signaling pathway that generates the light response in ON-bipolar cells, however, is more complex, and the molecular mechanisms remain to be elucidated. The ON-bipolar cell signaling pathway originates with a unique metabotropic glutamate receptor, mGluR6, which is found on the dendrites of ON-bipolar cells. mGluR6 acts via a G-protein, GO, to regulate the activity of an unidentified cation channel such that the light-induced decrease in synaptic glutamate opens the channel and depolarizes the cell. Recently, it has been reported that CSNB in Appaloosa horses is associated with a mutation causing a reduced expression of the TRPM1 cation channel. We hypothesize that TRPM1, and possibly other related TRP channels, are the cation channels coupled to mGluR6 that mediate the depolarizing light response of ON- bipolar cells. We further suggest that mutations in TRP channels will cause CSNB. Using a combination of biochemical, immunohistochemical, and electrophysiological approaches, we will test this hypothesis by answering the following questions: 1. Which TRP channel variants are expressed in ON-bipolar cells? 2. Do mice that carry null mutations in TRP channels expressed in bipolar cells have CSNB? 3. Can the physiological and pharmacological properties of retinal ON bipolar cell responses be reproduced in transfected HEK cells expressing the proper combination of TRP channel variants? The data from this study will contribute to the elucidation of the signaling pathway in the ON-bipolar cell, a fundamental, yet poorly understood, step in visual processing.

项目总结/摘要 先天性静止性夜盲是一组非进行性视网膜疾病 以暗视觉受损为特征。许多基因的突变已被证明与 关于CSNB它们通常影响光感受器和二阶双极神经元之间的突触传递 细胞当突变基因仅在视杆细胞或视杆双极细胞中表达时，表型仅限于夜间 失明然而，当突变基因的功能也需要突触之间的锥传递 和视锥双极细胞，进一步的视觉症状是明显的，如近视，远视，眼球震颤， 视力下降。一个这样的例子是GRM 6（编码mGluR 6的基因）中的突变，其引起突变。 CSNB的常染色体隐性形式。 在视网膜中，视觉信息被分离成响应于视网膜中的光的增加和减少的通路。 光照强度在第一个视网膜突触，感光细胞末梢紧张性释放谷氨酸 在黑暗中保持高的突触浓度，而在对光的反应中降低。两种类型的 突触后细胞，即ON-和OFF-双极细胞，以相反的极性响应由突触后细胞释放的谷氨酸。 光感受器，从而建立相反的视觉通路。在关闭双极细胞中的信号基础， 其依赖于离子型谷氨酸受体的激活。信号通路， 然而，在ON-双极细胞中产生光响应的分子机制更为复杂， 仍有待阐明。ON-双极细胞信号通路起源于一种独特的代谢型 谷氨酸受体，mGluR 6，其在ON双极细胞的树突上发现。mGluR 6通过G蛋白起作用， GO，以调节未鉴定的阳离子通道的活性，使得光诱导的突触减少， 谷氨酸盐打开通道并使细胞去极化。 最近，有报道称，阿帕卢萨马的CSNB与导致 TRPM 1阳离子通道的表达减少。我们假设TRPM 1和其他可能的相关基因 TRP通道是与mGluR 6偶联的阳离子通道，其介导ON的去偏振光响应。 双极细胞我们进一步认为TRP通道的突变会导致CSNB。结合使用 生物化学，免疫组织化学和电生理学方法，我们将测试这一假设， 回答以下问题：1.哪些TRP通道变体在ON双极细胞中表达？2.做 在双极细胞中表达的TRP通道中携带无效突变的小鼠具有CSNB？3.生理上的 在转染的HEK细胞中再现视网膜ON双极细胞反应的药理学性质 表达TRP通道变体的正确组合？这项研究的数据将有助于 阐明ON-双极细胞中的信号通路，这是一个基本的，但知之甚少的，视觉系统中的一个步骤。 处理.

项目成果

Voriconazole, an antifungal triazol that causes visual side effects, is an inhibitor of TRPM1 and TRPM3 channels.

伏立康唑是一种抗真菌三唑，会引起视觉副作用，是 TRPM1 和 TRPM3 通道的抑制剂。

• DOI: 10.1167/iovs.14-15270
• 发表时间: 2015
• 期刊: Investigative ophthalmology & visual science
• 影响因子: 4.4
• 作者: Xiong,Wei-Hong;Brown,RLane;Reed,Brian;Burke,NealS;Duvoisin,RobertM;Morgans,CatherineW
• 通讯作者: Morgans,CatherineW