Phototransduction in Health and Disease

摘要 视杆细胞中存在的视紫红质分子捕捉到光的光子后，暗视就开始了。 感光细胞。光感受器视紫红质的激活启动了一系列生化反应 这种反应称为光传导，会导致细胞超极化。这样做的长期目标是 研究计划是为了了解在生物化学事件背后的分子机制 正常状态和疾病状态下的光转导。目前的焦点是视紫红质。重要的是 这种分子超越了它在光转导中的中心作用。视紫红质起着重要的结构作用 对光感受器细胞的正常形成和健康是必不可少的。视紫红质基因是一个研究热点 导致遗传性视力障碍的突变，如视网膜色素变性和先天性夜盲， 目前还没有治愈方法。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 提供对这个蛋白质超家族中在结构和结构上具有共性的其他成员的见解 行动机制。尽管视紫红质有丰富的知识可用，但其准确的机制 目前还没有关于光感受器突变的影响的机械性描述 视力障碍是不完全的。目前的提议是基于前一个供资期间的调查结果， 支持对经典教条进行扩展的范式；即，视紫红质形成 在健康和疾病状态下的超分子结构，并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。这项提案的目的是在更多的方面审查这些范例 详细说明并考虑光感受器细胞生物学和视网膜疾病的含义。第一个目标是， 光感受器细胞中观察到的视紫红质膜组织的决定因素将被表征。 在第二个目标中，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将是 以细胞和小鼠模型为特征。在第三个目标中，视紫红质的结构性活性的起源 突变体的特征将是更好地评估先天性夜盲等疾病的机制 和Leber先天性黑发症。需要重大的技术进步来克服固有的 研究膜蛋白以观察重要的天然结构和分子细节的困难 为了更好地理解这个系统。这项提议利用了几种创新的生物物理方法，包括原子 力显微镜、Förster共振能量转移和傅里叶变换红外显微光谱。 我们的研究结果将导致一个更准确的机制框架来理解 遗传性视网膜疾病的系统正常和功能障碍，这将提供新的途径 用于科学研究。在解决视紫红质结构的基本方面和 这一功能将导致靶向治疗的发展和新药物靶点的发现。

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.