Molecular Pathophysiology of Retinal Degeneration in Bardet-Biedl Syndrome

描述(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，纤毛运输基因突变是遗传性光感受器退化的最常见原因之一。然而，由于纤毛运输缺陷导致光感受器退化的潜在机制还知之甚少。这项拟议研究的长期目标是通过了解与纤毛运输缺陷相关的光感受器退化的分子机制来提高治疗潜力。Bardet-Biedl综合征(BBS)是一种人类遗传性疾病，与睫状体运输缺陷有关，导致光感受器退化。最近，我们和其他人发现BBS蛋白参与了纤毛和质膜之间特定的货物蛋白的运输，BBS蛋白的鉴定对BBS的病因学具有重要的意义。这里，我们假设BBS蛋白在光感受器细胞的内段和外段之间运输特定的货物蛋白，这些货物的运输缺陷是视网膜变性的病理生理学基础。在本项目中，我们将通过以下具体目标鉴定BBS蛋白：1)利用转基因小鼠鉴定BBS蛋白及其调节子；2)利用iTRAQ对BBS视网膜光感受器外段进行定量蛋白质组学分析；3)阐明BBSome蛋白及其调控因子在疾病机制中的生物学意义。在初步研究中，我们从与BBS相关的几个组织中分离和鉴定了BBSome相互作用蛋白。我们还发现，与视网膜色素变性或Leber先天性黑色素有关的几种蛋白质在BBS外段减少。我们将进一步扩展这些发现，并阐明BBS中光感受器退化的分子基础。这项研究最终将为BBS蛋白维持正常光感受器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变相关视网膜变性的药物提供知识基础。

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.