Phototransduction in Health and Disease

摘要 暗视觉是由存在于视杆细胞中的视紫红质分子捕获光子而引发的 感光细胞光受体视紫红质的激活启动了一系列生化反应， 光传导反应，导致细胞超极化。长期目标是 研究计划是了解生物化学事件背后的分子机制， 正常和疾病状态下的光转导。目前的焦点是视紫红质。的重要性 该分子超出了其在光传导中的中心作用。视紫红质起着重要的结构作用 并且对于感光细胞的正常形成和健康是必需的。视紫红质基因是 突变导致遗传性视力障碍，如视网膜色素变性和先天性夜盲症， 目前没有治愈方法。视紫红质是一种典型的G蛋白偶联受体，因此这里的发现可以 提供了对这个蛋白质超家族的其他成员的见解，这些成员在结构上具有共同点， 行动机制。尽管有丰富的知识可用于视紫红质，其准确的机制， 作用仍然是不可用的，对光受体突变的影响的机械描述导致 视力障碍是不完整的。目前的提议是基于上一个供资期的调查结果， 是在支持范式扩展的经典教条;即，这一概念，视紫红质形成一个 在健康和患病状态下都具有超分子结构，并且能够实现多种活性状态， 其中一些可能只在疾病中表现出来。本提案的目的是在更多的方面审查这些范例。 详细说明并考虑感光细胞生物学和视网膜疾病的影响。在第一个目标中， 将表征在感光细胞中观察到的视紫红质膜组织的决定因素。 在第二个目标中，将研究引起视网膜色素变性的视紫红质突变体的错误折叠和聚集。 在细胞和小鼠模型中表征。在第三个目标中，视紫红质组成活性的起源 突变体的特征将更好地评估疾病的机制，如先天性夜盲症 和利伯先天性黑蒙需要重大的技术进步来克服内在的 研究膜蛋白的困难在于观察天然的结构和分子细节， 更好地了解系统。该提案利用了几种创新的生物物理方法，包括原子 力显微镜、福斯特共振能量转移和傅里叶变换红外显微光谱。 从我们的研究结果将导致一个更准确的机制框架，以了解功能的 系统在正常条件下和遗传性视网膜疾病的功能障碍，这将提供新的途径 进行科学研究在解决视紫红质结构的基本方面的长期影响， 功能将导致靶向治疗的发展和新的药物靶点的发现。

Abstract Scotopic vision is initiated upon capture of a photon of light by rhodopsin molecules present in rod photoreceptor cells. The activation of the light receptor rhodopsin sets into motion a series of biochemical reactions called phototransduction, which leads to the hyperpolarization of the cell. The long-term goal of this research program is to understand the molecular mechanisms underlying the biochemical events in phototransduction under normal and diseased states. The current focus is on rhodopsin. The importance of this molecule extends beyond its central role in phototransduction. Rhodopsin plays an important structural role and is essential for the proper formation and health of photoreceptor cells. The rhodopsin gene is a hot spot for mutations causing inherited vision disorders such as retinitis pigmentosa and congenital night blindness, which currently have no cure. Rhodopsin is a prototypical G protein-coupled receptor and therefore findings here can provide insights on other members of this superfamily of proteins that share commonalities in structure and mechanisms of action. Despite the wealth of knowledge available for rhodopsin, an accurate mechanism of its action is still unavailable and a mechanistic description on the effect of mutations in the light receptor causing vision disorders is incomplete. The current proposal is based on findings from the previous funding period that were in support of paradigms expanding on classical dogma; namely, the notion that rhodopsin forms a supramolecular structure in both healthy and diseased states and is able to achieve multiple active states, some of which may manifest only in disease. The aims of this proposal examine these paradigms in more detail and consider the implications in photoreceptor cell biology and retinal disease. In the first aim, determinants of the observed membrane organization of rhodopsin in photoreceptor cells will be characterized. In the second aim, the misfolding and aggregation of rhodopsin mutants causing retinitis pigmentosa will be characterized in cells and mouse models. In the third aim, the origin of constitutive activity in rhodopsin mutants will be characterized to better assess the mechanism of diseases such as congenital night blindness and Leber congenital amaurosis. Significant technological advances are required to overcome the intrinsic difficulties in studying membrane proteins to observe native structural and molecular details that are important to better understand the system. This proposal utilizes several innovative biophysical methods including atomic force microscopy, Förster resonance energy transfer, and Fourier transform infrared microspectroscopy. Results from our studies will lead to a more accurate mechanistic framework to understand the function of the system under normal conditions and dysfunctions in inherited retinal diseases, which will provide new avenues for scientific inquiry. The long-term impact in addressing fundamental aspects of rhodopsin structure and function will lead to the development of targeted therapeutics and discovery of novel drug targets.