Glutathione S-Transferase Pi in Age-Related Macular Degeneration

描述(申请人提供)：老年性黄斑变性(AMD)是发达国家老年人致盲的主要原因。氧化损伤与AMD的发病机制有关。视网膜的需氧量很高，由于视觉的复杂、活跃的光化学反应，它面临着光损伤的风险。人类黄斑中集中的是饮食中的胡萝卜素类抗氧化剂叶黄素和玉米黄质，已发现AMD患者的这两种抗氧化剂的水平低于老年对照眼。最近，谷胱甘肽S转移酶(GSTP1)的pi亚型被鉴定为人黄斑中的玉米黄质结合蛋白。谷胱甘肽S转移酶是一类细胞内解毒酶家族，通过与谷胱甘肽结合，催化包括反应性氧化物种在内的亲电体的还原。GSTP1已被证明在氧化损伤中发挥作用，作为玉米黄质结合蛋白的GSTP1在黄斑定位表明，它在调节黄斑中抗氧化剂的水平方面发挥着重要作用。我们的初步数据显示，与正常的老年对照眼相比，AMD患者GSTP1的表达减少。我们推测，GSTP1的表达减少导致黄斑对氧化应激的易感性，从而导致AMD的发病。长期目标是了解AMD发病的分子机制，并开发有效的预防和治疗策略。我们的假设将通过三个具体目标进行检验。具体目标1将确定人类视网膜中GSTP1水平的降低是否伴随着年龄和AMD。具体目标2将确定小鼠视网膜中GSTP1的小鼠对应物的减少是否会模仿小鼠的AMD表型。具体目标3将解决GSTP1过度表达是否在光诱导的视网膜损伤小鼠模型中提供了对抗氧化损伤的保护。拟议的研究将利用临床眼科诊断、免疫组织化学、Western分析以及电生理学。 公共卫生相关性：项目描述：我们建议调查谷胱甘肽S转移酶(GSTP1)的pi亚型在老年性黄斑变性(AMD)的病理中是否在氧化损伤中发挥作用。我们将测定GSTP1在人AMD和对照视网膜中的表达，以及与正常对照小鼠相比，伴随GSTP1过度表达和降低的视网膜表型。

DESCRIPTION (provided by applicant): Age-related macular degeneration (AMD) is the leading cause of blindness among the elderly in the developed countries. Oxidative damage has been implicated in AMD pathogenesis. The retina has a high oxygen demand and is at risk for light-induced damage because of the complex, active photochemical reactions of vision. Concentrated in the human macula are dietary carotenoid antioxidants lutein and zeaxanthin, and their levels have been found to be lower in AMD compared to elderly control eyes. Recently, the pi isoform of glutathione S-transferase (GSTP1) has been identified as a zeaxanthin-binding protein in the human macula. Glutathione S-transferases are a family of intracellular detoxification enzymes that catalyze the reduction of electrophiles, including reactive oxidative species, by conjugating them to glutathione. GSTP1 has been shown to play a role in oxidative damage, and macular localization of GSTP1 as a zeaxanthin-binding protein suggests that it plays an important role in modulating the levels of antioxidants in the macula. Our preliminary data revealed that GSTP1 expression is decreased in AMD compared to normal elderly control eyes. We hypothesize that decreased expression of GSTP1 renders susceptibility to oxidative stress in the macula, leading to AMD pathogenesis. The long-term goals are to understand the molecular mechanism of AMD pathogenesis and to develop effective preventative and therapeutic strategies. Our hypothesis will be tested with three specific aims. Specific Aim 1 will determine if decreased levels of GSTP1 accompany age and AMD in human retina. Specific Aim 2 will determine whether reduction of the murine counter-part of GSTP1 in mouse retina will mimic the AMD phenotype in mice. Specific Aim 3 will address if GSTP1 over-expression provides protection against oxidative damage in a light-induced retinal damage murine model. The proposed studies will utilize clinical ophthalmic diagnosis, immunohistochemistry, Western analysis, as well as electrophysiology. PUBLIC HEALTH RELEVANCE: Project Narrative: We propose to investigate whether the pi isoform of glutathione S-transferase (GSTP1) plays a role in oxidative damage in the pathology of age-related macular degeneration (AMD). We will determine the GSTP1 expression in human AMD and control retina as well as the retinal phenotype concomitant with GSTP1 over-expression and reduction compared to normal control mice.