Retinal degeneration and chloride channels.

描述（由申请人提供）：在没有放大的情况下阅读本页的能力取决于黄斑的完整性，黄斑是视网膜的一小块区域，包括中央凹。黄斑变性是发达国家致盲的主要原因。年龄相关性黄斑变性（AMD）是一种进行性黄斑变性，大约20%的65岁以上的人患有此病，但其病因尚不清楚。提出这一建议的假设是，CI电流在视网膜色素上皮（RPE）吞噬脱落光感受器盘的过程中发挥作用。由于类维甲酸和脂褐素在视网膜下空间的积累，这一过程中的缺陷可导致黄斑变性。我们认为CI通道在正常吞噬过程中是重要的，因为它们在摄入大量外段时参与细胞体积的调节。多种已知的CI通道，包括CFTR、CIC-2、CIC-3和CIC-5在RPE细胞中表达，最近有研究表明，导致Best黄斑营养不良的RPE蛋白bestrophin是一个新的CI通道家族的创始成员。该项目的目标是表征在RPE细胞中表达的CI电流，特别是strophin介导的电流，并了解其功能。有三个具体目标。(1)确定strophin CI通道的性质。我们将通过膜片钳分析异种表达的strophins，来检验strophins是氯离子通道亚基的假设。(2)表征RPE细胞中的氯离子通道。这一目标验证了以下假设：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，并将其与已知的CI通道（包括strophin）的特性进行比较。(3)确定CI通道在光感受器盘吞噬中的作用。这一目的将验证CI通道在RPE细胞吞噬杆状细胞外节中起重要作用的假设。这一假设将通过确定药物抑制剂和CI电流的反义敲低对RPE吞噬杆外段的影响来验证。

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.