CHEMICAL ARCHITECTURE OF RETINA CIRCUITS

视网膜电路的化学结构

• 批准号: 2711138
• 负责人: NOGA VARDI
• 金额: $ 24.69万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-08-01 至 1999-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2711138
• 关键词: G protein; GABA receptor; Primates; adenylate cyclase; amacrine cells; cats; chemical structure; chloride channels; computer simulation; cone cell; dopamine receptor; electron microscopy; gap junctions; horizontal cell; human tissue; immunocytochemistry; in situ hybridization; laboratory rat; mathematical model; neuroanatomy; polymerase chain reaction; retinal bipolar neuron; rod cell; second messengers; visual photoreceptor

DESCRIPTION (Adapted from applicant's abstract): The parallel neural circuits in mammals that connect photoreceptors to several specific types of ganglion cell have been identified in nearly complete detail. The major missing information now concerns 'chemical architecture', that is, which specific ion channels, receptors and second messengers are expressed by each neuron in a circuit and in what region of each cell. The proteins at issue belong to multigene families whose isoforms differ functionally (e.g. binding affinity, conductance, temporal gating, and desensitization), and the ensemble of such properties sets the behavior of each circuit. The applicant proposes to identify for several multigene families the particular isoforms expressed in specific types of neuron. This will be accomplished by isolating an identified neuron, amplifying its mRNA, and probing the amplified message with known nucleotide sequences for the various isoforms. The isoforms so identified will then be localized immunocytochemically at the subcellular level by electron microscopy. The neurons to be studied are: rods, cones, horizontal cells (types A and B) and AII amacrine cells. These cells are chosen because their circuits are known and characterized computationally. The proteins to be identified and localized include the connexins (aim 1) and a subset of their known modulatory proteins (D1 dopamine receptor, Golf, and adenylyl cyclase III) (aim 2), plus the ligand-gated ion channels, GABA alpha and GABA rho (aim 3). The connexins are important because they mediate electrical coupling (homotypic and/or heterotypic) that affects signal processing (filtering, averaging, switching). The modulators are important because they govern the degree of coupling in various circuits (which is tuned to match environmental luminance). The role of G-proteins and their activators in modulating degree of coupling will be determined by dye coupling in superfused whole mount retinas. The GABA A and GABA rho subunits are important because they mediate feedback and feedforward inhibition and are undoubtedly critical to gain control. The new information regarding chemical architecture will be incorporated into computational models of the rod bipolar and cone bipolar circuits to assess (by simulation) how modulation of coupling and inhibition (feedback and feedforward) affect bipolar cell gain control (aim 4). By characterizing the chemical architecture of known circuits, and then simulating the results, the proposed project would provide a basis for understanding the principles of circuit design in retina. This will help assess the molecular basis of human visual performance and identify losses due to mutations of specific isoforms.

描述（改编自申请人的摘要）：平行神经 将光感受器连接到几种特定类型的哺乳动物的电路 神经节细胞已经几乎完整地鉴定出来。这 现在，主要缺少信息涉及“化学体系结构”，也就是说 哪些特定的离子通道，受体和第二使者是 由每个电路中的每个神经元和每个细胞的哪个区域表示。 有争议的蛋白质属于多基因家族的同工型不同 在功能上（例如，结合亲和力，电导，时间门控和 脱敏），此类属性的合奏设置了行为 每个电路。申请人建议确定几个 多基因家族以特定类型表达的特定同工型 神经元。这将通过隔离确定的神经元来实现 扩增其mRNA，并用已知的扩增消息探测扩增的消息 各种同工型的核苷酸序列。同工型 然后，确定的将在亚细胞上进行局部免疫细胞化学。 电子显微镜的水平。要研究的神经元是：杆， 锥体，水平细胞（A型和B型）和AII无长熟细胞。这些 之所以选择单元格，是因为它们的电路是已知和表征的 计算。要识别和本地化的蛋白质包括 连接蛋白（AIM 1）及其已知调节蛋白的子集（D1 多巴胺受体，高尔夫和腺苷酸环化酶III）（AIM 2），加上 配体门控离子通道，GABA Alpha和Gaba Rho（AIM 3）。这 连接素很重要，因为它们介导电气耦合 （同型和/或异型）影响信号处理 （过滤，平均，开关）。调节器很重要，因为 他们控制各个电路中的耦合程度（已调整 匹配环境亮度）。 G蛋白及其的作用 调节耦合程度的激活剂将由染料确定 在超级式整个坐骑视网膜上耦合。 GABA A和GABA RHO 亚基很重要，因为它们介导了反馈和进料 抑制作用，无疑对于获得控制至关重要。新的 有关化学体系结构的信息将纳入 杆双极和锥双极电路的计算模型 评估（通过模拟）如何调节耦合和抑制 （反馈和进料）影响双极细胞增益控制（AIM 4）。 通过表征已知电路的化学体系结构，然后 模拟结果，拟议的项目将为 了解视网膜中电路设计的原理。这将有所帮助 评估人类视觉表现的分子基础并识别 由于特定同工型的突变引起的损失。