Recapitulation of the two-cell visual cycle in photoreceptors and its effects on retinoid flux and remedy of toxic retinoid species

光感受器中双细胞视觉周期的概括及其对类视黄醇通量的影响以及有毒类视黄醇种类的补救

• 批准号: 10609438
• 负责人: Zachary John Engfer
• 金额: $ 4.25万
• 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: 2022-04-01 至 2025-03-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10609438
• 关键词: 11 cis Retinal; 11-cis-Retinol; Affect; Age; All-Trans-Retinol; Back; Binding; Biochemical; Biochemical Pathway; Biochemistry; Blindness; Brain; Cell Death; Cells; Chemicals; Chronic; Cone; Coupled; Coupling; Darkness; Defect; Degenerative Disorder; Disease; Electrophysiology (science); Electroretinography; Engineering; Enzymes; Esters; Ethanolamines; Eye; Fatty Acids; Functional disorder; Future; Genetic; Health; Helper-Inducer T-Lymphocyte; High Pressure Liquid Chromatography; Human; Immunohistochemistry; Immunology; Isomerism; Kinetics; Knock-in; Knock-in Mouse; Knock-out; Knockout Mice; Knowledge; Lasers; Lead; Light; Link; Molecular; Molecular Biology; Molecular Evolution; Morphology; Muller' s cell; Mus; Natural regeneration; Ophthalmoscopy; Opsin; Optic Nerve; Optical Coherence Tomography; Patients; Phenotype; Photoreceptors; Phototransduction; Physiological; Pigments; Proteins; Quality of life; RPE65 protein; Reaction; Recycling; Regenerative pathway; Research Technics; Resistance; Retina; Retinal Degeneration; Retinal Diseases; Retinal Dystrophy; Retinal Pigments; Retinal dehydrogenase; Retinoids; Retinol dehydrogenase; Rod; Scanning; Signal Transduction; Structure of retinal pigment epithelium; Supporting Cell; Testing; Therapeutic; Therapeutic Intervention; Training; Travel; Vertebrate Photoreceptors; Vision; Visual; Visual Fields; Visual impairment; Work; cell killing; cell type; chromophore; crosslink; experience; lecithin-retinol acyltransferase; mouse model; remediation; retinal damage; retinol isomerase; sex; stem; therapeutic gene; treatment optimization; vision science; visual cycle

PROJECT SUMMARY/ ABSTRACT. Retinal degenerative (RD) diseases result in a progressive loss of vision, and have a devastating impact on a patient’s quality of life. Many genetic factors that nucleate these diseases are intricately linked to defects in the visual (retinoid) cycle. This cycle is necessary for regenerating the essential visual pigment 11-cis-retinal after it is photoisomerized to all-trans-retinal; errors in this multi-step recycling of all-trans-retinal back to 11-cis- retinal leads to the buildup of toxic retinoid photo-oxidation products that can kill photoreceptors and the supporting retinal pigment epithelium (RPE). Few therapeutic options exist for mitigating the damage that is caused by these photo-oxidation products, especially after cell death in the retina has started to affect quality of vision. Normally, the vertebrate visual cycle is distributed across two distinct cell types, the retinal pigment epithelium and the photoreceptors (i.e., rods and cones). In the functional visual cycle, 11-cis-retinal is initially bound to opsin proteins within the photoreceptors, where it is then isomerized to all-trans-retinal in the presence of light. This transformation initiates the phototransduction signaling cascade that travels through optic nerve to the brain, where the signals are integrated into a coherent visual field. The all-trans-retinal molecules are then shed by opsins and converted to all-trans-retinol by all-trans-retinal dehydrogenase. The all-trans-retinol is then transported from the photoreceptors to one of two “helper” cell types- RPE cells that support both rod and cone function, and Müller cells that solely support cones. Because RPE-linked visual cycle dysfunction has a greater impact on the retina as a whole, we’ve elected to focus on just the RPE-based visual cycle and not the cone- exclusive alternative visual cycle. When all-trans-retinol is transported from the photoreceptors to the RPE, the all-trans-retinol undergoes two key reactions; one catalyzed by lecithin-retinol acyltransferase (abbr. Lrat), and the other by retinal pigment epithelium-specific 65 kDa (abbr. Rpe65). Lrat catalyzes the coupling of all-trans retinol to fatty acids, forming stable retinyl ester intermediates. These retinyl esters are subsequently isomerized and hydrolyzed by Rpe65 to give 11-cis-retinol. 11-cis-retinol is then oxidized to 11-cis-retinal by 11-cis-retinol dehydrogenases and transported back to the photoreceptors for re-use. When the visual cycle is hindered, all-trans retinal can build up in the photoreceptors, leading to the formation of toxic photo-oxidation products that cause retinal degeneration. I intend to expand our knowledge of the visual cycle via engineered expression of Lrat and Rpe65 in the photoreceptors. In studying how manipulation of retinoid flux in the visual cycle controls the emergence and progression of RD, we can optimize therapeutic interventions that target the central drivers of retinal disease, while simultaneously reversing the toxic buildup of retinoids in chronic RD.

项目摘要/摘要。 视网膜退行性(RD)疾病会导致进行性视力丧失，并对 患者的生活质量。导致这些疾病的许多遗传因素与大脑中的缺陷有着复杂的联系。 视觉(类维甲酸)周期。这个循环对于再生基本的视觉色素11顺式视网膜是必要的。 它被光异构化为全反式视网膜；错误的是这种多步循环的全反式视网膜回到11顺式- 视网膜会导致有毒的类维A酸光氧化产物的积聚，这种产物可以杀死光感受器和 支持视网膜色素上皮(RPE)。几乎没有什么治疗选择可以减轻这种损害 由这些光氧化产物引起的，特别是在视网膜细胞死亡已经开始影响质量之后 远见卓识。 正常情况下，脊椎动物的视觉周期分布在两种不同的细胞类型上，即视网膜色素上皮 以及感光器(即视杆和视锥)。在功能视觉周期中，11顺式视网膜最初被绑定到 光感受器中的视蛋白，然后在光存在的情况下，它被异构化为全视网膜。 这种转变启动了光转导信号级联，通过视神经传递到 大脑，在那里信号被整合到一个连贯的视野中。然后全跨视网膜的分子 由视黄素脱落，经全反式视黄醇脱氢酶转化为全反式视黄醇。然后是全反式视黄醇 从感光器运输到两种“辅助”细胞类型之一--既支持视杆细胞又支持视锥细胞的RPE细胞 功能，以及仅支持圆锥体的Müler单元。因为RPE相关的视觉周期障碍有更大的 对整个视网膜的影响，我们选择只关注基于RPE的视觉周期，而不是视锥- 独一无二的另类视觉循环。当全反式视黄醇从光感受器输送到RPE时， 全反式视黄醇经历了两个关键反应：一个是由卵磷脂-视黄醇酰基转移酶催化的。Lrat)，以及 另一种是由视网膜色素上皮特异的65 kDa(缩写)。RPE65)。LRAT催化全反式偶联 视黄醇转化为脂肪酸，形成稳定的视黄酸酯中间体。这些视黄酸酯随后被 经RPE65异构化、水解制得11-顺式视黄醇。然后11-顺式视黄醇被氧化成11-顺式视黄醇 11-顺式视黄醇脱氢酶，并运输回感光器以供重复使用。当视觉周期为 受阻的全反式视网膜可以在感光器中积聚，导致有毒的光氧化形成。 导致视网膜退化的产品。 我打算通过工程表达LRAT和RPE65来扩大我们对视觉周期的了解 光感受器。在研究视黄素流量在视觉周期中的操纵如何控制出现和 对于RD的进展，我们可以优化针对视网膜疾病的中心驱动因素的治疗干预措施， 同时逆转慢性RD患者维甲酸的毒性积聚。