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.

项目总结/摘要。 视网膜退行性（RD）疾病导致视力的进行性丧失，并且对视力造成破坏性影响。 患者的生活质量。许多导致这些疾病的遗传因素都与基因缺陷有着错综复杂的联系。 视（类维生素A）周期。这个循环对于在视网膜变性后再生基本的视觉色素11-顺式-视网膜是必需的。 它被光异构化为全反式-视黄醛;全反式-视黄醛多步再循环回11-顺式- 视网膜导致有毒的类维生素A光氧化产物的积累，这些产物可以杀死光感受器， 支持视网膜色素上皮（RPE）。几乎没有治疗方法可以减轻 由这些光氧化产物引起，特别是在视网膜细胞死亡后， 视觉。 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，视网膜色素上皮细胞， 而光感受器（即，视杆细胞和视锥细胞）。在功能性视觉周期中，11-顺式-视黄醇最初与 光感受器内的视蛋白，然后在光存在下异构化为全反式视网膜。 这种转化启动了光转导信号级联，通过视神经到达视网膜。 大脑，信号被整合到一个连贯的视野中。然后，全反式视网膜分子 由视蛋白脱落并由全反式视黄醇脱氢酶转化为全反式视黄醇。全反式视黄醇 从光感受器转移到两种“辅助”细胞类型之一-支持视杆细胞和视锥细胞的RPE细胞 Müller细胞仅支持视锥细胞。因为RPE相关的视觉周期功能障碍有更大的 作为一个整体的视网膜的影响，我们已经选择只关注RPE为基础的视觉周期，而不是锥- 独家另类视觉循环。当全反式视黄醇从光感受器转运到RPE时， 全反式视黄醇经历两个关键反应;一个由卵磷脂-视黄醇酰基转移酶（abbr. Lrat），以及 另一种是视网膜色素上皮特异性65 kDa（abbr. Rpe65）。Lrat催化全反式 视黄醇转化为脂肪酸，形成稳定的视黄酯中间体。这些视黄基酯随后被 异构化并通过Rpe 65水解，得到11-顺式-视黄醇。11-顺式-视黄醇然后被氧化成11-顺式-视黄醛， 11-顺式-视黄醇脱氢酶，并转运回光感受器重新使用。当视觉周期是 受阻的全反式视黄醛可以在光感受器中积聚，导致有毒光氧化的形成 导致视网膜退化的产品。 我打算通过Lrat和Rpe 65在视网膜中的工程表达来扩展我们对视觉周期的认识。 光感受器在研究视觉周期中类维生素A流量的操纵如何控制出现， 随着视网膜病变的进展，我们可以优化针对视网膜疾病核心驱动因素的治疗干预措施， 同时逆转慢性RD中类维生素A的毒性积聚。