Delivery of signaling and structural proteins to photoreceptor outer segment

描述(由申请人提供)：这项建议的总体目标是将我们对光感受器细胞外段发生的信号传递过程的机械理解与负责维持该细胞器的蛋白质组成的细胞过程的框架结合起来。为此，目标1将继续我们对转导蛋白的GTP酶激活蛋白复合体的长期研究，重点放在其功能的细胞和催化方面之间的相互作用。在AIMS 2和3中，将分析视紫红质的类似相互作用，它在光感受器细胞中有三个不同的作用：信号(光转导级联的激活)、结构(盘膜的构建材料)和靶向(引导将视紫红质和可能的其他蛋白质，如GTPase激活复合体运输到外段的小泡的流动)。我们将首先测试视紫红质在指导外节囊泡运输中的作用是否可以从它的其他主要功能中分离出来，然后确定视紫红质的结构功能是否可以被其他定位于光感受器盘的膜蛋白所取代。最后，目标4将阐明负责运送外段功能的其他蛋白质的运输途径。我们将专注于光感受器盘沿蛋白，外周蛋白-2/RDS，这是最有可能使用细胞内靶向机制替代视紫红质的候选蛋白。拟议的实验与理解光感受器细胞生物学中最基本的问题有关，也是理解与蛋白质信号、靶向和运输缺陷相关的多种类型光感受器退化的原因的关键。 与公共健康相关：本申请中提出的研究涉及负责感光细胞光敏室功能的分子和细胞机制，光感受器细胞的外层部分。由于日常光照的不利影响，外段的建筑材料大约每10天就要更换一次，这需要高度有组织的蛋白质从细胞内的生物合成机器到这个隔间的巨大流动。这些通路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，这突显了了解蛋白质信号转导、运输和组装成大型功能复合体的机制的重要性。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 proposal is to integrate our mechanistic understanding of the signaling processes that take place in the outer segment of photoreceptor cells with the framework of the cellular processes responsible for maintenance of the protein composition of this organelle. To this end, Aim 1 will continue our longstanding investigation of the GTPase activating protein complex for transducin with an emphasis on the interplay between the cellular and catalytic aspects of its function. In Aims 2 and 3 a similar interplay will be analyzed for rhodopsin, which has three distinct roles in photoreceptor cells: signaling (activation of the phototransduction cascade), structural (building material of the disc membranes) and targeting (directing the flow of vesicles transporting rhodopsin and likely other proteins, e.g. the GTPase activating complex, to the outer segment). We will first test whether the role of rhodopsin in directing outer segment vesicular transport can be dissociated from its other major functions and then determine whether the structural function of rhodopsin can be replaced by other membrane proteins made to localize to the photoreceptor discs. Finally, Aim 4 will elucidate trafficking pathways responsible for the delivery of other proteins functioning in the outer segment. We will focus on a photoreceptor disc rim protein, peripherin-2/RDS, which is the most likely known candidate for using an intracellular targeting mechanism alternative to rhodopsin. The proposed experiments are relevant to understanding the most basic issues in photoreceptor cell biology and are key for understanding the causes of many types of photoreceptor degeneration associated with defects in protein signaling, targeting and trafficking. PUBLIC HEALTH RELEVANCE: The studies proposed in this application address the molecular and cellular mechanisms responsible for the functioning of the light-sensitive compartment of the photoreceptor cells, the outer segment. Because of adverse effects of daily light exposure, the building materials of the outer segment have to be replaced approximately every ten days, which requires an enormous flow of highly organized protein trafficking from the intracellular biosynthetic machinery to this compartment. Dysfunction of these pathways causes some of the most severe types of inherited degenerative diseases of the retina, highlighting the importance of understanding the mechanisms underlying protein signaling, trafficking and assembly into large functional complexes. Elucidating these mechanisms is essential for developing strategies for disease prevention and future therapeutic interventions.