Retinal degeneration and chloride channels.

视网膜变性和氯离子通道。

• 批准号: 6927865
• 负责人: H. CRISS HARTZELL
• 金额: $ 30.4万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-08-01 至 2007-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6927865
• 关键词: Xenopus; antisense nucleic acid; biophysics; calcium; calmodulin; cell morphology; cellular polarity; chloride channels; eye pharmacology; human tissue; ion transport; ligands; macular degeneration; membrane permeability; phagocytosis; phosphorylation; polymerase chain reaction; protein quantitation /detection; protein structure function; retinal pigment epithelium; rod cell; site directed mutagenesis; tamoxifen; transfection; voltage /patch clamp

DESCRIPTION (provided by applicant): The ability to read this page without magnification depends upon the integrity of the macula, a small region of the retina including the fovea. Macular degeneration is the leading cause of blindness in developed countries. Age-related macular degeneration (AMD) is a progressive degeneration of the macula that affects approximately 20% of individuals over the age of 65, but its causes remain unknown. The hypothesis driving this proposal is that CI currents play a role in phagocytosis of shed photoreceptor discs by the retinal pigment epithelium (RPE). Defects in this process can lead to macular degeneration as the result of accumulation of retinoids and lipofuscin pigment in the subretinal space. We propose that CI channels are important in normal phagocytosis because they are involved in the regulation of cell volume during ingestion of large quantities of outer segments. A variety of well-known CI channels including CFTR, CIC-2, CIC-3, and CIC-5 are expressed in RPE cells and recently it has been suggested that bestrophin, an RPE protein that causes Best macular dystrophy, is the founding member of a new family of CI channels. The goal of this project is to characterize the CI currents, especially bestrophin-mediated currents, that are expressed in RPE cells and to understand their function. There are three specific aims. (1) To determine the properties of bestrophin CI channels. We will test the hypothesis that bestrophins are subunits of a chloride channel by patch clamp analysis of heterologously expressed bestrophins. (2) To characterize chloride channels in RPE cells. This aim tests the hypothesis that several types of CI channels are functionally specialized for specific RPE functions. The strategy is to use whole-cell and patch clamp recording to characterize CI channels in RPE cells and to compare them to the properties of known CI channels, including bestrophin. (3) To determine the role of CI channels in photoreceptor disc phagocytosis. This aim will test the hypothesis that CI channels are important in phagocytosis of rod outer segments by RPE cells. This hypothesis will be tested by determining the effects of pharmacological inhibitors and antisense knockdown of CI currents on the phagocytosis of rod outer segments by RPE.

描述（由申请人提供）：在不放大的情况下阅读本页的能力取决于黄斑的完整性，黄斑是视网膜的一个小区域，包括中央凹。黄斑变性是发达国家失明的主要原因。年龄相关性黄斑变性 (AMD) 是一种进行性黄斑变性，影响大约 20% 的 65 岁以上个体，但其原因仍不清楚。推动这一提议的假设是 CI 电流在视网膜色素上皮 (RPE) 吞噬脱落的感光盘中发挥作用。这一过程中的缺陷可能会由于类维生素A和脂褐素色素在视网膜下腔中的积累而导致黄斑变性。我们认为 CI 通道在正常吞噬作用中很重要，因为它们在摄入大量外部节段时参与细胞体积的调节。多种众所周知的 CI 通道，包括 CFTR、CIC-2、CIC-3 和 CIC-5 在 RPE 细胞中表达，最近有人提出，黄斑黄蛋白（一种导致 Best 黄斑营养不良的 RPE 蛋白）是 CI 通道新家族的创始成员。该项目的目标是表征 RPE 细胞中表达的 CI 电流，尤其是黄斑黄蛋白介导的电流，并了解其功能。具体目标有三个。 (1)确定黄斑黄蛋白CI通道的特性。我们将通过异源表达的卵黄蛋白的膜片钳分析来检验卵黄蛋白是氯离子通道亚基的假设。 (2) 表征 RPE 细胞中的氯离子通道。这一目标测试了以下假设：几种类型的 CI 通道在功能上专门用于特定的 RPE 功能。该策略是使用全细胞和膜片钳记录来表征 RPE 细胞中的 CI 通道，并将其与已知 CI 通道（包括黄斑蛋白）的特性进行比较。 (3)确定CI通道在感光盘吞噬作用中的作用。这一目标将检验 CI 通道在 RPE 细胞吞噬杆外节中发挥重要作用的假设。该假设将通过确定药物抑制剂和 CI 电流反义敲除对 RPE 吞噬杆外节的影响来检验。