Formation and New Components of the Usher 2 Protein Complex in Photoreceptors

描述（由申请人提供）：Usher综合征是视力和听力损失最常见的疾病。这种病无药可治。我们的长期目标是了解Usher综合征视网膜变性的分子机制，这将为开发有效的治疗方法奠定坚实的基础。本文主要关注光感受器中由USH2A、VLGR1和WHRN组成的蛋白复合物的形成及其新组分。编码这三种蛋白质的基因是Usher综合征2型的致病基因，这是Usher综合征最常见的形式。我们最近的研究表明，Usher 2蛋白复合物位于哺乳动物光感受器的睫状膜复合体（PMC）上。这种蛋白复合物的缺陷导致PMC周围的超结构异常，最终导致光感受器细胞死亡。然而，该复合物的形成、组成和生物学功能在很大程度上尚不清楚。本研究的中心假设是，WHRN作为一种支架蛋白，与Usher 2蛋白复合物的USH2A、VLGR1等组分结合，这些组分参与了整个复合物在光受体中的功能。为了验证这一假设，将解决两个具体目标。在具体的目标1中，将使用一系列体外和体内系统的生化试验来深入研究USH2A、VLGR1和WHRN之间的相互作用。将探讨三元配合物存在的可能性。在特定目标2中，将研究光感受器中Usher 2蛋白复合物的两个新发现的候选组分。这些新成分在该复合物中的功能意义将在其突变小鼠中进一步分析。该研究将对Usher 2蛋白复合物在光感受器中的功能产生新的认识，并可能应用于毛细胞。因此，这项研究将有助于填补我们对Usher综合征视网膜变性和听力损伤机制的认识空白，这可能对未来Usher综合征治疗策略的发展有价值。此外，该研究将更好地理解PMC在光感受器细胞生物学中的作用。

DESCRIPTION (provided by applicant): Usher syndrome is the most common condition with vision and hearing loss. There is no cure for this disease. Our long-term goal is to understand the molecular mechanisms of retinal degeneration in Usher syndrome, which will lay a solid foundation for developing effective therapies for this disease. The main focus of this proposal is the formation and new components of the protein complex composed of USH2A, VLGR1 and WHRN in photoreceptors. The genes encoding these three proteins are the causative genes for Usher syndrome type 2, the most common form of Usher syndrome. Our recent research has demonstrated that the Usher 2 protein complex is located at the periciliary membrane complex (PMC) in mammalian photoreceptors. Defects in this protein complex cause ultra structural abnormalities surrounding the PMC and eventually lead to photoreceptor cell death. However, the formation, composition and biological function of this complex are largely not clear. The central HYPOTHESIS of this study is that WHRN, as a scaffold protein, associates with USH2A, VLGR1 and other components of the Usher 2 protein complex, and that these components contribute to the function of the whole complex in photoreceptors. To test this hypothesis, two specific aims will be addressed. In specific aim 1, interactions among USH2A, VLGR1 and WHRN will be thoroughly studied using a series of biochemical assays in both in vitro and in vivo systems. The possibility of the existence of a ternary complex will be explored. In specific aim 2, two newly identified candidate components of the Usher 2 protein complex will be studied in photoreceptors. The functional significance of these new components in this complex will be further analyzed using their mutant mice. This study will generate new insight into the function of the Usher 2 protein complex in photoreceptors, which may be applied in hair cells as well. Therefore, this study will help fill the gap in our knowledge about the mechanisms underlying retinal degeneration and, perhaps, hearing impairment in Usher syndrome, which might be valuable for the future development of therapeutic strategies for Usher syndrome. Furthermore, this study will provide a better understanding of the role of the PMC in photoreceptor cell biology. PUBLIC HEALTH RELEVANCE: Defects in the Usher 2 multi-protein complex cause Usher syndrome type 2, a condition with both retinitis pigmentosa and congenital hearing impairment. This proposal is to investigate the formation of this complex and its potential new components. Completion of this work is expected to provide more complete insight into the biological function of this complex and the disease mechanism underlying Usher syndrome.