Retinal degeneration and chloride channels

描述(申请人提供)：人类Bestrophin-1(HBest1)的突变与最佳卵黄样黄斑营养不良(BVMD)、成人起病的卵黄样黄斑营养不良(AVMD)和常染色体显性遗传性玻璃体视网膜脉络膜病(ADVIRC)有关，但hBest1的确切功能仍不确定，hBest1功能障碍与疾病的联系机制尚不清楚。有强有力的证据表明，hBest1是一种阴离子通道。也有证据表明hBest1调节电压门控钙通道。这一应用将验证hBest1是一种多功能蛋白的假设，它既是一个氯通道，可能具有质膜和细胞内功能，又是包括钙通道在内的其他离子通道的调节因子。HBest1的突变被认为是通过在视网膜色素上皮(RPE)水平上扰乱视网膜中的离子运输而产生视网膜疾病。我们认为，跨RPE的离子传输的中断导致光感受器和RPE之间的间隙中的液体含量和成分异常。这损害了RPE和光感受器之间的相互作用，有利于维甲酸衍生色素的积累和卵黄样病变的发展。在这一应用中，我们将利用分子、遗传和电生理相结合的方法，利用hBest1和hBest1突变体的培养细胞、hBest1基因中断或突变的转基因小鼠以及新鲜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。这些研究不仅将为卵黄状黄斑营养不良的发病机制提供重要的见解，而且还将阐明跨视网膜色素上皮的离子转运在正常视网膜内稳态中的作用。公共卫生相关性：这项研究解决了黄斑变性的机制，黄斑变性是导致失明的主要原因之一。具体地说，我们将调查一种名为Bestrophin的蛋白质的功能障碍是如何导致一种遗传性青少年型黄斑变性的。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深入的见解。

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.