MOLECULAR BIOLOGY OF RETINA-SPECIFIC GABA RECEPTORS

γ-氨基丁酸（GABA）是一种主要的视网膜神经递质， 可以在多种视网膜受体上发挥作用。 其中一些受体 是配体门控离子通道，可能类似于GABA/A受体 在大脑中有显著的表达。 互补DNA编码14 不同的GABA/A受体亚单位排列成4个主要类别（α， β、γ和δ）已经从大脑中克隆出来。 我们有 最近描述了通过cDNA发现的GABA rho亚基类 克隆。 视网膜中GABA rho1的表达至少是正常人的20倍。 它在其他组织中的表达。 这种视网膜特异性受体 亚基具有独特的结构特征， 同源寡聚受体显示独特的药理学和生理学 特色 从视网膜cDNA中分离的第二个rho亚基 一个文库在视网膜RNA中以较低水平表达， 结构和功能特征与rho1亚基相似。 这 该申请提出研究这种生物学特性。 不同类别的视网膜GABA受体亚单位，并探讨其 通过追求以下目标，在视网膜病理学中可能发挥的作用： 1)分析rho的基因组组织和相对方向 基因，包括详细检查推定的启动子区域， 每个基因 2)确定GABA rho 1或rho 2突变是否导致常染色体 黄斑营养不良的主要形式，最近已被映射到 与rho基因相同的染色体区域（6q13-q21）。 3)确定可选拼接表单的其他成员是否 GABA rho亚基家族的基因在视网膜中表达 使用源自rho cDNA的引物扩增视网膜cDNA 序列的 4)执行结构/功能分析，以确定 GABA rho cDNA序列赋予了 这是这类子单元的特性。 5)确定哪些视网膜细胞类型表达GABA rho亚单位 使用RNA的北方和PCR分析，原位杂交和 免疫组织化学技术。

Gamma amino butyric acid (GABA) is a major retinal neurotransmitter than can function at a variety of retinal receptors. Some of these receptors are ligand-gated ion channels, probably similar to the GABA/A receptors prominently expressed in the brain. Complementary DNAs encoding 14 different GABA/A receptor subunits arranged in 4 major classes (alpha, beta, gamma, and delta) have been cloned from the brain. We have recently described a GABA rho subunit class discovered through cDNA cloning. GABA rho1 expression in retina is at least 20-fold greater than its expression in any other tissue. This retina-specific receptor subunit has distinctive structural features and avidly associates into homo-oligomeric receptors displaying unique pharmacologic and physiologic characteristics. A second rho subunit isolated from a retinal cDNA library is expressed at lower levels in retina RNA but displays structural and functional features similar to the rho1 subunit. This application proposes to investigate the molecular biology of this distinct class of retinal GABA receptor subunits and to explore their possible roles in retinal pathology by pursuit of the following aims: 1) Analyzing the genomic organization and relative orientation of the rho genes including detailed examination of the putative promoter regions of each gene. 2) Determining whether mutations in GABA rho1 or rho2 cause an autosomal dominant form of macular dystrophy which has recently been mapped to the same chromosomal region (6q13-q21) as the rho genes. 3) Ascertaining whether additional members of alternatively-spliced forms of the GABA rho subunit family are expressed in retina by PCR amplification of retinal cDNA using primers derived from rho cDNA sequences. 4) Performing structure/function analysis to determine which portions of the GABA rho cDNA sequences confer the pharmacologic and physiologic properties characteristic of this subunit class. 5) Ascertaining which retinal cell types express the GABA rho subunits using Northern and PCR analysis of RNA, in situ hybridization and immunohistochemical techniques.