G PROTEIN PATHWAYS AND REGULATION IN RPE CELLS

RPE 细胞中的 G 蛋白途径和调节

• 批准号: 3265660
• 负责人: HENRY K FONG
• 金额: $ 18.89万
• 依托单位: DOHENY EYE INSTITUTE
• 依托单位国家: 美国
• 财政年份: 1990
• 资助国家: 美国
• 起止时间: 1990-08-01 至 1997-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3265660
• 关键词: G protein; biological signal transduction; complementary DNA; gene expression; genetic promoter element; genetically modified animals; human genetic material tag; immunocytochemistry; in situ hybridization; laboratory mouse; laboratory rabbit; laboratory rat; melatonin; northern blottings; nucleic acid sequence; phospholipase C; receptor coupling; retinal pigment epithelium; retinaldehyde; retinoid binding proteins; serotonin; substance P; tachykinin; tissue /cell culture; western blottings

Regulation of the functions of the retinal pigment epithelium (RPE) may involve receptors and G proteins that are expressed preferentially in RPE cells. Our past efforts to identify novel G proteins in RPE cells have been successful. We have also investigated G protein signaling mechanisms in RPE cells by molecular cloning of RPE-specific cDNAs that may encode the components of signal transduction pathways. Our recent findings point to the presence of a unique receptor-mediated G protein-coupled process in the RPE cell. We have identified in bovine RPE cells a novel G protein-coupled receptor, tentatively referred to as RPE-retinal G protein-coupled receptor or RGR. This novel heptahelical receptor is notably homologous, to the subfamily of visual pigments, and it has been shown by in situ hybridization to be selectively expressed in RPE cells, cells in the inner nuclear layer, and specific cells of the ganglion cell layer. It is not expressed in the photoreceptors, or in tissues other than the retina, except possibly the brain. The localization of this receptor in the RPE, the high level of expression of its mRNA, and its homology to the visual pigments suggest that the function of this receptor is important in the visual process involving the RPE. The RGR gene may encode a novel opsin homologue that binds retinaldehyde. Its function may be to catalyze retinaldehyde isomerization or act as a trapping protein for 11-cis-retinal. An alternative function of RGR may be to mediate a novel G protein response pathway by binding to an activating ligand and coupling to a heterotrimeric G protein. We predict that the RGR gene is highly conserved in vertebrates. The abundance of RGR in the RPE cell would strongly suggest that it participates in a major and specialized role of the RPE. We will test these and other hypotheses by biochemical characterization of the RGR gene product. The objectives of this proposal are to further characterize the RGR gene, determine the putative receptor function of RGR, and elucidate specialized G protein pathways and regulation in RPE cells. The molecular cloning of this selectively expressed opsin or retinochrome homologue provides an entry point for further investigation of RPE function, differentiation, and disease.

对视网膜色素上皮（RPE）功能的调节可能 涉及在RPE中优先表达的受体和G蛋白 细胞。我们过去识别RPE细胞中新型G蛋白的努力具有 成功。我们还研究了G蛋白信号传导机制 在RPE细胞中通过RPE特异性cDNA的分子克隆可能编码 信号转导途径的组成部分。我们最近的发现 在存在中存在独特的受体介导的G蛋白偶联过程 RPE单元格。 我们已经在牛RPE细胞中鉴定出一种新型的G蛋白偶联受体， 暂时称为RPE视网膜G蛋白偶联受体或RGR。 这部小说的七旋赫基受体显然是同源的，与亚科 视觉颜料的原位杂交已显示为 在RPE细胞中有选择地表达，内部核层中的细胞， 神经节细胞层的特定细胞。它没有在 受感受器或视网膜以外的组织中的感光器，除了可能 脑。 该受体在RPE中的定位，高水平 其mRNA的表达及其与视觉色素的同源性表明 该受体的功能在视觉过程中很重要 涉及RPE。 RGR基因可以编码结合视网膜醛的新型Opsin同源物。 它的功能可能是催化视网膜醛异构化或充当 捕获11盘视网膜的蛋白质。 RGR的另一种功能可能是 通过与激活结合来介导新的G蛋白反应途径 配体并偶联与异三聚体G蛋白。我们预测RGR 基因在脊椎动物中高度保守。 RPE中的RGR丰度 细胞会强烈建议它参与专业， RPE的专业角色。 我们将通过生化表征来检验这些假设和其他假设 RGR基因产品。该提议的目标是进一步 表征RGR基因，确定推定的受体功能 RGR和RPE中的专业G蛋白途径和调节 细胞。该有选择表达的Opsin的分子克隆或 视网膜化同源物提供了进一步研究的切入点 RPE功能，分化和疾病。