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）： 与年龄相关的黄斑变性（AMD）是一种令人衰弱的老年衰老疾病，在退伍军人人群中的患病率正在增加。目前尚无萎缩性（干）AMD的高效疗法，这是该疾病的最常见形式。现在认为，维生素是代谢物，全反视网膜的，可能在AMD的发病机理中起关键作用。全反视网膜在光感受器细胞中通过光线激活后，从视觉颜料（棒和锥蛋白）中释放出来。为了持续的视力，必须连续提供11次视网膜电视网膜，以便保持足够水平的光敏感性全粘蛋白。杆和锥形感受器从称为视觉循环的代谢途径中接收11 cis-视视网膜，该途径涉及位于视网膜色素上皮的酶。有充分的证据表明，在视网膜中也存在替代性的müller细胞依赖性视觉周期，可为锥形光感受器提供额外的视觉发色团供应，足以在白天照明条件下进行操作。通过靶向经典的视觉周期异构酶RPE65来抑制生产11-CIS视网膜的药物，通过减少暴露后的全反视网膜释放的量，预防对视网膜的光诱导的损害。这些药物已被提议作为AMD的潜在药物疗法。目前，正在评估一种称为Emixustat的RPE依赖性视觉周期的抑制剂，其在3期临床试验中降低AMD进展的能力。 RPE65抑制HOL的巨大承诺是治疗干AMD的有效药物，但它们也对锥形感受器和色觉有不良的副作用。这些麻烦的眼副作用的起源仍有待阐明，但它们可能是由于脱靶互动而引起的 由于在人类黄斑中发生的圆锥体的丰度与AMD病理学发生的圆锥体相比，由于圆锥体的丰富性，因此也可以想象，对Müller细胞依赖性视觉周期的部分抑制可能对AMD治疗是热有益的。最近，在高通量表达式筛选中鉴定出了基于müller细胞途径的候选类维生素类异构体，称为Sphingolipid-Δ4-2饱和酶（DES1）。这种Müller细胞 - 定位酶最初以二氢可胺的去饱和酶为特征，在RPE65 - / - 小鼠中过表达时，显示出来自全反元素 - 返合醇在体外催化CIS视黄醇异构体的形成，并部分恢复视网膜功能。但是，该酶对锥细胞功能的生理贡献尚未研究。该提案的目的是1）评估DES1使用基因敲除小鼠模型对锥介导的视力的生理贡献，2）在Emixustat的最近获得的高分辨率结构信息上资本化，在Emixustat对RPE65活性位点的结合模式上，以设计新型的视觉循环抑制剂，对RPE65进行高度选择，并改善了对毒性prifiels。 DES1中的视网膜结构和功能将通过高分辨率成像和电视图评估。结构引导的药物设计将用于生成高选择性的RPE65抑制剂，以用于处理干燥AMD的潜在用途。