Studies on visual cycles and their relevance to age-related macular degeneration

视觉周期及其与年龄相关性黄斑变性的相关性研究

• 批准号: 8921484
• 负责人: Philip David Kiser
• 金额: --
• 依托单位: LOUIS STOKES CLEVELAND VA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-04-01 至 2020-04-01
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8921484
• 关键词: 11 cis Retinal; Active Sites; Adolescent; Advanced Development; Adverse effects; Age; Age related macular degeneration; All-Trans-Retinol; Atrophic; Binding; Cell physiology; Cells; Cellular Structures; Chemicals; Color Visions; Complex; Cone; Deposition; Development; Disease; Drug Design; Drug Targeting; Electron Microscopy; Electroretinography; Enzymes; Evaluation; Exhibits; Future; Goals; Growth; Human; Image; Immunohistochemistry; In Vitro; Isomerase; Isomerism; Knock-out; Knockout Mice; Lead; Lesion; Life; Light; Lighting; Lipofuscin; Mediating; Metabolic Pathway; Metabolism; Molecular; Mouse Strains; Mus; Natural regeneration; Neuroglia; Opsin; Pathogenesis; Pathology; Pathway interactions; Patients; Pharmaceutical Preparations; Pharmacodynamics; Pharmacotherapy; Phase III Clinical Trials; Photoreceptors; Phototransduction; Physiological; Physiology; Play; Population; Prevalence; Production; Proteins; Quality of life; RPE65 protein; Reaction; Research; Resolution; Retina; Retinal; Retinal Cone; Retinal Pigments; Retinoids; Rodent; Role; Sphingolipids; Stargardt' s disease; Structure; Structure of retinal pigment epithelium; Testing; Therapeutic; Therapeutic Agents; Toxic effect; Vascular Endothelial Growth Factors; Vertebral column; Vertebrate Photoreceptors; Veterans; Vision; Visual; Vitamin A; adduct; attenuation; base; chromophore; desaturase; design; dihydroceramide desaturase; drug candidate; effective therapy; geographic atrophy; improved; in vivo; inhibitor/antagonist; insight; macula; mouse model; neovascular; novel; operation; overexpression; public health relevance; response; retinal damage; retinal rods; retinol isomerase; tool; visual cycle

 DESCRIPTION (provided by applicant): Age-related macular degeneration (AMD) is a debilitating blinding disease of older age that is increasing in prevalence in the Veteran population. There are currently no highly effective therapies for atrophic (dry) AMD, the most common form of this disorder. It is now appreciated that the vitamin A metabolite, all-trans-retinal, likely plays a key role in the pathogenesis of AMD. All-trans-retinal is released from visual pigments (rod and cone holo-opsins) in photoreceptor cells following their activation by light. For sustained vision, 11-cis-retinal must e continuously provided to the photoreceptor cells so that sufficient levels of light-sensitive holo-opsins are maintained. Rod and cone photoreceptors receive 11-cis-retinal from a metabolic pathway known as the visual cycle, which involves enzymes located in the retinal pigment epithelium. There is strong evidence that an alternative, Müller cell-dependent visual cycle also exists in the retina to provide cone photoreceptors with an additional supply of visual chromophore adequate for operation under daytime lighting conditions. Agents that inhibit production of 11-cis-retinal by targeting the classical visual cycle isomerase, RPE65, protect against light-induced damage to the retina by reducing the amount of all-trans-retinal released after light exposure. These agents have been proposed as potential pharmacotherapies for AMD. One inhibitor of the RPE-dependent visual cycle, called emixustat, is currently being evaluated for its ability to slow AMD progression in a phase 3 clinical trial. RPE65 inhibitors hol great promise as effective agents for the treatment of dry AMD, but they also have undesirable side effects on cone photoreceptors and color vision. The origin of these troublesome ocular side effects remains to be elucidated, but they could potentially arise from off-target interaction with components of the Müller cell-dependent visual cycle. Alternatively, because of the abundance of cones over rods in the human macula where AMD pathology occurs it is also conceivable that partial inhibition of the Müller cell-dependent visual cycle could be therapeutically beneficial for AMD treatment. Recently, a candidate retinoid isomerase of the Müller cell-based pathway, called sphingolipid-Δ4-desaturase (DES1), was identified in a high-throughput expression screen. This Müller cell-localized enzyme, originally characterized as a dihydroceramide desaturase, was shown to catalyze formation of cis retinol isomers from all-trans-retinol in vitro and partially restore retinal function when overexpressed in Rpe65-/- mice. However, the physiological contribution of this enzyme to cone cell function has not yet been studied. This proposal aims to 1) evaluate the physiological contribution of DES1 to cone-mediated vision using knockout mouse models and 2) capitalize on recently acquired high-resolution structural information on the binding mode of emixustat to the RPE65 active site to design novel visual cycle inhibitors with high selectively towards RPE65 and improved toxicity profiles. Retinal structure and function in Des1 conditional knockout mice will be assessed by high resolution imaging and electroretinography. Structure-guided drug design will be used to generate highly selective RPE65 inhibitors for potential use in the treatment of dry AMD.

 描述（由申请人提供）： 年龄相关性黄斑变性 (AMD) 是一种使人衰弱的致盲性疾病，在退伍军人群体中患病率不断增加，目前尚无针对萎缩性（干性）AMD 的高效治疗方法，这是这种疾病最常见的形式。现在认识到，维生素 A 代谢物全反式视网膜可能在 AMD 的发病机制中发挥着关键作用，全反式视网膜是从视色素（视杆细胞和视锥细胞全视蛋白）中释放出来的。感光细胞被光激活后，为了保持视力，必须持续向感光细胞提供 11-顺式视网膜，以便维持足够水平的光敏全视蛋白。一种称为视觉循环的代谢途径，涉及视网膜色素上皮中的酶。有强有力的证据表明，另一种依赖于穆勒细胞的视觉循环也存在于视网膜色素上皮细胞中。视网膜为视锥光感受器提供足够的视觉生色团，足以在白天照明条件下工作。通过靶向经典视觉循环异构酶 RPE65 抑制 11-顺式视网膜的产生，可防止光引起的视网膜损伤。这些药物被认为是治疗 AMD 的一种潜在药物疗法，称为 RPE 依赖性视觉周期抑制剂。 emixustat 目前正在一项 3 期临床试验中评估其减缓 AMD 进展的能力，它有望成为治疗干性 AMD 的有效药物，但它们也对视锥细胞和色觉产生不良副作用。这些麻烦的眼部副作用仍有待阐明，但它们可能是由脱靶相互作用引起的 或者，由于发生 AMD 病理的人类黄斑中存在丰富的视锥细胞，因此可以想象，部分抑制 Müller 细胞依赖性视觉周期可能对 AMD 具有治疗益处。最近，一种基于 Müller 细胞途径的候选视黄醇异构酶，称为鞘脂-Δ4-去饱和酶 (DES1)，在高通量中被鉴定出来。这种 Müller 细胞定位酶最初被定性为二氢神经酰胺去饱和酶，在体外催化全反式视黄醇形成顺式视黄醇异构体，并在 Rpe65-/- 小鼠中过度表达时部分恢复视网膜功能。该酶对视锥细胞功能的生理贡献尚未研究。该提案的目的是 1) 使用基因敲除评估 DES1 对视锥细胞介导的视觉的生理贡献。小鼠模型；2) 利用最近获得的关于 emixustat 与 RPE65 活性位点结合模式的高分辨率结构信息，设计出对 RPE65 具有高选择性的新型视觉周期抑制剂，并改善 Des1 条件敲除小鼠的视网膜结构和功能。将通过高分辨率成像和视网膜电图进行评估，将用于生成高选择性 RPE65 抑制剂，用于治疗干性 AMD。