Formation of Retinyl-Opsins by Retinyl Formate as Molecular Shades Against Light-Induced Retinal Damage

视黄基甲酸形成视黄基视蛋白作为抗光诱导视网膜损伤的分子色调

• 批准号: 10560484
• 负责人: John Dong-Hoon Hong
• 金额: $ 4.38万
• 依托单位: UNIVERSITY OF CALIFORNIA-IRVINE
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-01-24 至 2026-01-23
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10560484
• 关键词: 11 cis Retinal; Adolescent; Affect; Age; Age related macular degeneration; All-Trans-Retinol; American; Attenuated; Back; Binding; Biological Assay; Blindness; Bruch' s basal membrane structure; Child; Complex; Contact Lenses; Dangerousness; Darkness; Deposition; Development; Dimerization; Disease Progression; Dose; Drusen; Electroretinography; Exposure to; Eye; Formates; Future; Genes; Glass; High Pressure Liquid Chromatography; Histology; Impairment; Individual; Inherited; Intervention; Knockout Mice; Lasers; Legal Blindness; Light; Lipids; Lipofuscin; Macular degeneration; Measures; Mediating; Membrane; Membrane Transport Proteins; Mind; Modification; Molecular; Molecular Conformation; Morphology; Mus; Mutation; Nuclear; Ophthalmoscopy; Opsin; Optical Coherence Tomography; Oxidoreductase; Patients; Phenotype; Photoreceptors; Phototransduction; Physical condensation; Pre-Clinical Model; Production; Property; Proteins; Quality of life; Reaction; Retina; Retinal Photoreceptors; Retinal Pigments; Retinitis Pigmentosa; Retinoids; Rhodopsin; Rod Outer Segments; Scanning; Site; Stargardt' s disease; Structure of retinal pigment epithelium; Testing; Therapeutic; Thick; Visible Radiation; Vision; Work; absorption; adduct; alpha Subunit Transducin; analog; autosome; chromophore; crosslink; dimer; in vivo; inhibitor; legally blind; light intensity; macula; mouse model; neuroprotection; prevent; retinal damage; success; translocase; visual cycle

Project Summary/Abstract Stargardt disease (STGD1) is the most common form of inherited juvenile macular degeneration. STGD1 is caused by autosomal recessive mutations in the ABCA4 gene, which encodes a membrane transporter that removes all-trans-retinals (atRALs) from photoreceptors as part of the retinoid cycle. Free atRALs or their bisretinoid condensation products promote photo-oxidative damage to the macula as seen in STGD1. The same atRAL-mediated damage can also be seen in age-related macular degeneration (AMD), which is expected to affect at least 18 million Americans by 2050. The production of atRAL starts at the level of opsin proteins, which reside within photoreceptor outer segment disc membranes. Light is captured by opsin- chromophore complexes, or visual pigments, causing their native bound chromophore, 11-cis-retinal (11cRAL), to be converted to atRAL and forming activated opsins. These activated opsins initiate phototransduction and are eventually spontaneously hydrolyzed to apo-opsin and atRAL. Exposure to intense light causes photoreceptor overstimulation and dangerously high levels of atRAL, potentially leading to photoreceptor damage and loss. Recently, a chromophore analogue, retinyl formate (RF), was found to irreversibly bind apo- opsin and form retinyl-opsins that can no longer form visual pigments with 11cRAL. These retinyl-opsins also absorb light outside the visible light spectrum and do not subsequently release atRAL upon light absorption. Thus, RF can potentially reduce the proportion of visual pigments in the retina and thereby reduce the atRAL burden during periods of intense light exposure. Therefore, I hypothesize that RF can serve as a molecular shade at the opsin level, providing long-lasting protection to photoreceptors from light-induced damage. In this proposal, I will characterize the site of the retinyl modification on opsin by RF, distinguishing whether RF binding is competitive or allosteric with 11cRAL. I will determine if and how retinyl-opsins also could initiate the phototransduction cascade. To investigate its applicability to a pre-clinical model, I will study whether RF treatment of an STGD1 mouse model provides neuroprotection to photoreceptors against intense light exposure via formation of retinyl-opsins and reduction of retinal atRAL and determine the relative proportion of retinyl-opsins and remaining natural visual pigments. This work thus serves as a proof-of-concept approach to determining whether disabling a proportion of opsins with an irreversible inhibitor of visual pigment formation could prevent light-induced damage to photoreceptors, and point to the development of future therapeutics and interventions for STGD1 and AMD.

项目总结/摘要 Stargardt病（STGD 1）是遗传性青少年黄斑变性最常见的形式。STGD 1是 由ABCA 4基因的常染色体隐性突变引起，ABCA 4基因编码一种膜转运蛋白， 作为类维生素A循环的一部分，从光感受器中去除全反式视黄醇（atRALs）。自由atRALs或其 双视黄酸缩合产物促进对黄斑的光氧化损伤，如在STGD 1中所见。的 同样的atRAL介导的损伤也可以在年龄相关性黄斑变性（AMD）中看到， 预计到2050年将影响至少1800万美国人。atRAL的产生始于视蛋白水平 蛋白质，其驻留在感光器外节盘膜内。光被视蛋白捕获- 发色团复合物或视色素，导致其天然结合的发色团，11-顺式-视黄醛（11 cRAL）， 转化为atRAL并形成活化的视蛋白。这些激活的视蛋白启动光转导， 最终自发水解为脱辅基视蛋白和atRAL。暴露在强光下会导致 光感受器过度刺激和危险的高水平atRAL，可能导致光感受器 损害和损失。最近，发现发色团类似物甲酸视黄酯（RF）不可逆地结合载脂蛋白， 视蛋白并形成视网膜酰视蛋白，其不再与11 cRAL形成视色素。这些视黄基视蛋白还 吸收可见光谱外的光，并且随后在光吸收时不释放atRAL。 因此，RF可以潜在地降低视网膜中视色素的比例，从而降低atRAL。 在强光照射期间的负担。因此，我假设RF可以作为一种分子 在视蛋白水平的阴影，提供持久的保护光感受器免受光诱导的损害。在这 建议，我将表征视蛋白的视黄基修饰的RF网站，区分RF是否 与11 cRAL的结合是竞争性的或变构的。我将确定视黄酸视蛋白是否以及如何也可以启动 光转导级联为了研究其对临床前模型的适用性，我将研究RF是否 STGD 1小鼠模型的治疗为光感受器提供了抗强光的神经保护 通过形成视黄基视蛋白和减少视网膜atRAL的暴露，并确定 视黄基视蛋白和剩余的天然视色素。因此，这项工作可以作为一种概念验证方法， 确定是否用视色素形成的不可逆抑制剂使一定比例的视蛋白失能 可以防止光诱导的光感受器损伤，并指出未来治疗方法的发展， STGD 1和AMD的干预。