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: 10390090
• 负责人: John Dong-Hoon Hong
• 金额: $ 4.22万
• 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/10390090
• 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; Deposition; Development; Dimerization; Disease; Dose; Drusen; Electroretinography; Exposure to; Eye; Future; Genes; High Pressure Liquid Chromatography; Histology; Impairment; Individual; Inherited; Knock-out; 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; Retina; Retinal Photoreceptors; Retinal Pigments; Retinitis Pigmentosa; Retinoids; Rhodopsin; Rod Outer Segments; Scanning; Site; Stargardt' s disease; Structure of retinal pigment epithelium; Testing; Therapeutic Intervention; Thick; Visible Radiation; Vision; Work; absorption; adduct; alpha Subunit Transducin; analog; chromophore; crosslink; dimer; in vivo; inhibitor; macula; mouse model; neuroprotection; oxidative damage; 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.

项目摘要/摘要 Stargardt病(STGD1)是最常见的遗传性青少年黄斑变性。STGD1是 由常染色体隐性突变的ABCA4基因引起，该基因编码一种膜转运蛋白， 作为类维A酸循环的一部分，从光感受器中去除全反式视黄醇(AtRAL)。免费的ATRAL或他们的 双维A酸类缩合产物促进对黄斑的光氧化损伤，如STGD1所示。这个 在老年性黄斑变性(AMD)中也可以看到同样的由ATAL介导的损害，这是 预计到2050年，至少将有1800万美国人受到影响。视功能的产生始于视神经水平 存在于光感受器外节盘膜中的蛋白质。光被视蛋白捕获- 发色团复合体，或视觉色素，导致其天然结合的发色团，11顺式视网膜(11cral)， 转化为自体并形成激活的视蛋白。这些激活的视蛋白启动光转导和 最终自发地被水解为凋亡素和脱氧核糖核酸。暴露在强光下会导致 光感受器过度刺激和危险的高水平ATAL，潜在地导致光感受器 损坏和损失。最近，一种发色团类似物--视黄甲酸酯(Rf)被发现与apo-2不可逆结合。 视黄素，并形成视黄醇-视黄素，不能再与11中心形成视觉色素。这些视黄醇-视黄素也 吸收可见光光谱以外的光，吸收后不会释放出可见光。 因此，RF可以潜在地减少视网膜中视觉色素的比例，从而减少视网膜的损害 在强光照射期间的负担。因此，我假设Rf可以作为一种分子 在视蛋白水平遮荫，为光感受器提供持久的保护，以防光诱导的损害。在这 建议，我将用RF来表征视黄素的视黄醇修饰部位，区分RF 与11cre的结合为竞争性或变构结合。我将确定视黄醇-视黄素是否以及如何也能启动 光传导级联。为了研究它对临床前模型的适用性，我将研究RF是否 STGD1小鼠模型的治疗为光感受器提供了对抗强光的神经保护 通过形成视黄醇和视网膜减少暴露，并确定相对比例 视黄基视黄素和剩余的天然视觉色素。因此，这项工作可以作为一种概念验证方法 确定是否使用不可逆的视觉色素形成抑制剂来禁用一定比例的视蛋白 可以防止光诱导的光感受器损伤，并指明了未来治疗和 对STGD1和AMD的干预。