Retinal degeneration and chloride channels

描述（由申请人提供）：人乳朊蛋白-1突变（hBest1）与Best黄斑营养不良症（BVMD）、成人发病黄斑营养不良症（AVMD）和常染色体显性玻璃体视网膜脉络膜病（ADVIRC）有关，但hBest1的确切功能仍不清楚，hBest1功能障碍与疾病之间的联系机制尚不清楚。有强有力的证据表明hBest1是阴离子（Cl）通道。也有证据表明hBest1调节电压门控钙通道。该应用将测试hBest1是一种多功能蛋白的假设，它既是Cl通道，可能同时具有质膜和细胞内功能，也是其他离子通道的调节剂，包括Ca通道。hBest1基因的突变被认为是通过在视网膜色素上皮（RPE）水平上破坏视网膜中的离子运输而产生视网膜疾病。我们认为，通过RPE的离子运输中断导致光感受器和RPE之间空间的流体含量和组成异常。这损害了RPE和光感受器之间的相互作用，有利于类视黄酮衍生色素的积累和卵黄样病变的发展。在本研究中，我们将采用分子、遗传和电生理相结合的方法，通过转染hBest1和hBest1突变体的培养细胞、hBest1基因被破坏或突变的转基因小鼠以及新分离和培养的视网膜色素上皮细胞来研究hBest1的功能和病理生理机制。这些研究不仅将为黄斑营养不良的机制提供重要的见解，而且还将阐明通过视网膜色素上皮的离子运输在正常视网膜稳态中的作用。公共卫生相关性：本研究解决了黄斑变性的机制，失明的主要原因之一。具体地说，我们将研究一种被称为strophin的蛋白质的功能障碍是如何导致遗传性黄斑变性的幼年发病形式的。我们期望这些研究将为黄斑变性的机制和维持正常视网膜功能的机制提供见解。

DESCRIPTION (provided by applicant): Mutations in human bestrophin-1 (hBest1) are associated with Best vitelliform macular dystrophy (BVMD), adult-onset vitelliform macular dystrophy (AVMD), and autosomal dominant vitreoretinochoroidopathy (ADVIRC), but the precise function of hBest1 remains in doubt and the mechanisms linking hBest1 dysfunction with disease are unknown. There is strong evidence that hBest1 is an anion (Cl) channel. There is also evidence that hBest1 regulates voltage-gated Ca channels. This application will test the hypothesis that hBest1 is a multifunctional protein that is both a Cl channel, possibly with both plasma membrane and intracellular functions, and a regulator of other ion channels, including Ca channels. Mutations in hBest1 are hypothesized to produce retinal disease by disrupting ion transport in the retina at the level of the retinal pigment epithelium (RPE). We suggest that disruption of ion transport across the RPE results in abnormal fluid content and composition in the space between photoreceptors and RPE. This compromises the interaction between RPE and photoreceptors and favors accumulation of retinoid-derived pigments and development of vitelliform lesions. In this application, we will investigate the functions and pathophysiological mechanisms of hBest1 using a combination of molecular, genetic, and electrophysiological approaches with cultured cells transfected with hBest1 and hBest1 mutants, transgenic mice with disrupted or mutant hBest1 genes, and freshly-isolated and cultured retinal pigment epithelial cells. These studies will not only provide important insights into the mechanisms of vitelliform macular dystrophies, but will also shed light on the role of ion transport across the retinal pigment epithelium on normal retinal homeostasis. PUBLIC HEALTH RELEVANCE: This research addresses the mechanisms of macular degeneration, one of the major causes of blindness. Specifically, we will investigate how dysfunction of a protein called bestrophin causes an inherited juvenile-onset form of macular degeneration. We expect that these studies will provide insights into the mechanisms of macular degeneration and the mechanisms that maintain normal retinal function.