Ankyrin G in protein sorting between rod plasma membrane and photoreceptor discs

描述(申请人提供)：本申请的总体目标是探索膜细胞骨架在光感受器外节功能中的作用。膜细胞骨架修饰几乎所有细胞类型的质膜，为它们提供机械支持，并将选定的膜蛋白保留在专门的膜亚域中。令人惊讶的是，膜细胞骨架在光感受器中的作用直到最近才得到系统的研究，当时我们报道了环核苷酸门控通道2-亚基的外段靶向严重依赖于它与膜细胞骨架蛋白ankyrin G的相互作用。我们现在提出ankyrin G的另一个主要功能是将该通道和其他蛋白质保留在杆状外段质膜上，并防止它们分选到光受体盘中。在目标1中，我们将在环核苷酸门控通道的情况下测试这一假设。在目标2中，我们将在杆状外段中寻找其他的锚蛋白G结合伙伴。我们还将测试杆状细胞中其他蛋白质的选择性质膜定位是否依赖于它们与ankyrin G的结合。我们希望这项探索性研究的完成将产生足够的信息、概念和实验工具，以建立一个更大的计划，致力于了解膜细胞骨架在光感受器健康和疾病中的作用。 公共卫生相关性：本申请中提出的研究涉及负责光感受器细胞的光敏室的生物发生、维持和功能的分子和细胞机制，光感受器细胞的外层部分。这些过程的功能障碍会导致一些最严重的视网膜遗传性退行性疾病，包括但不限于视网膜色素变性。这突出了了解蛋白质运输到外层片段及其随后组装成大型功能复合体的基本机制的重要性。阐明这些机制对于制定疾病预防策略和未来的治疗干预措施至关重要。

DESCRIPTION (provided by applicant): The overall goal of this application is to explore the role of the membrane cytoskeleton in the functioning of photoreceptor outer segments. The membrane cytoskeleton decorates plasma membranes in essentially all cell types, providing them with mechanical support and retaining selected membrane proteins within specialized membrane sub-domains. Surprisingly, the role of the membrane cytoskeleton in photoreceptors had not been systematically addressed until very recently, when we reported that the outer segment targeting of the 2-subunit of the cyclic nucleotide-gated channel is critically dependent on its interaction with the membrane cytoskeleton protein ankyrin G. We now propose that another major function of ankyrin G is to retain this channel and other proteins at the rod outer segment plasma membrane and to prevent them from sorting into photoreceptor discs. In Aim 1 we will test this hypothesis for the case of the cyclic nucleotide-gated channel. In Aim 2 we will search for other ankyrin G binding partners in rod outer segments. We will also test whether selective plasma membrane localization of other proteins in rods is dependent on their binding to ankyrin G. We hope that the completion of this exploratory study will yield a sufficient body of information, concepts and experimental tools to build a larger program devoted to understanding the roles of the membrane cytoskeleton in photoreceptor health and disease. PUBLIC HEALTH RELEVANCE: The studies proposed in this application address the molecular and cellular mechanisms responsible for the biogenesis, maintenance and functioning of the light-sensitive compartment of the photoreceptor cells, the outer segment. Dysfunction of these processes causes some of the most severe types of inherited degenerative diseases of the retina, including but not limited to retinitis pigmentosa. This highlights the importance of understanding the mechanisms underlying the trafficking of proteins to the outer segment and their subsequent assembly into large functional complexes. Elucidating these mechanisms is essential for developing strategies for disease prevention and future therapeutic interventions.