Molecular Pathophysiology of Retinal Degeneration in Bardet-Biedl Syndrome

描述（由申请人提供）：光感受器退化是早发性失明的主要原因。越来越多的证据表明，纤毛运输基因的突变是遗传性光感受器变性的最常见原因之一。然而，由于纤毛运输缺陷导致的光感受器变性的潜在机制知之甚少。这项研究的长期目标是通过了解与纤毛运输缺陷相关的感光细胞变性的分子机制来提高治疗潜力。Bardet-Biedl综合征（BBS）是一种与导致光感受器变性的纤毛运输缺陷相关的人类遗传性疾病。最近，我们和其他人已经表明，BBS蛋白质参与纤毛和质膜之间的特定货物蛋白的运输，并且BBS蛋白货物的鉴定对BBS的病因学具有重要意义。在这里，我们假设BBS蛋白质运输特定的货物蛋白之间的感光细胞的内部和外部段和这些货物的运输缺陷的基础视网膜变性的病理生理。在这个项目中，我们将通过追求以下具体目标来识别感光细胞中的BBS蛋白质货物，并推进我们对BBS中感光细胞变性的潜在分子机制的理解：1）使用转基因小鼠和串联亲和纯化鉴定BBSome货物和调节剂，2）使用iTRAQ对来自BBS视网膜的光感受器外节进行定量蛋白质组学分析，3）阐明BBSome货物和调节剂在疾病机制方面的生物学意义。在初步研究中，我们分离和鉴定BBSome相互作用蛋白从几个组织相关的BBS。我们还发现，与视网膜色素变性或利伯先天性黑蒙相关的几种蛋白质在BBS外段减少。我们将进一步扩展这些发现，并阐明在BBS感光细胞变性的分子基础。这项研究最终将为BBS蛋白维持正常感光细胞功能的基本生物学机制提供有价值的见解，并为开发基于机制的治疗睫状体病相关视网膜变性提供知识基础。

DESCRIPTION (provided by applicant): Photoreceptor degeneration is a major cause of early onset blindness. Accumulating evidence indicates that mutations in ciliary trafficking genes are one of the most common causes of inherited photoreceptor degeneration. Yet, the underlying mechanisms of photoreceptor degeneration due to defective ciliary trafficking are poorly understood. The long-term objective of the proposed research is to advance therapeutic potential by understanding the molecular mechanisms of photoreceptor degeneration associated with defective ciliary trafficking. Bardet-Biedl Syndrome (BBS) is a human genetic disorder associated with ciliary trafficking defects that leads to photoreceptor degeneration. Recently, we and others have shown that BBS proteins are involved in the transport of specific cargo proteins between the ciliary and plasma membranes and that identification of BBS protein cargos has significant implications for the etiology of BBS. Here, we hypothesize that BBS proteins transport specific cargo proteins between the inner and outer segments of the photoreceptor cells and that the trafficking defects of these cargos underlie the pathophysiology of retinal degeneration. In this project, we will identify BBS protein cargos in the photoreceptor cells and advance our understanding of the underlying molecular mechanisms of photoreceptor degeneration in BBS by pursuing the following specific aims: 1) Identify BBSome cargos and regulators using transgenic mice and tandem affinity purification, 2) Perform quantitative proteomic analysis of photoreceptor outer segments from BBS retina using iTRAQ, and 3) Elucidate the biological significance of BBSome cargos and regulators with respect to disease mechanisms. In preliminary studies, we isolated and identified BBSome interacting proteins from several tissues relevant to BBS. We also found that several proteins that are associated with retinitis pigmentosa or Leber congenital amaurosis are decreased in the BBS outer segment. We will further extend these findings and elucidate the molecular basis of photoreceptor degeneration in BBS. This research will ultimately provide valuable insight into the basic biological mechanisms by which BBS proteins maintain normal photoreceptor cell function and also serve as a knowledge base for the development of mechanism-based therapies for ciliopathy-related retinal degenerations.