Impact of Lipofuscin in Retinal Pigment Epithelial Cells

描述(申请人提供)：拟议的研究计划致力于促进我们对视网膜色素上皮细胞(RPE)中积累的脂褐素在萎缩性黄斑变性的疾病过程中的作用机制的理解，包括年龄相关性和青少年(Stargardt病和最佳卵黄样黄斑营养不良)的形成。RPE细胞的脂褐素主要来源于感光细胞，很大程度上是由全反式视网膜反应产生的，全反式视网膜是视觉色素吸收光子时形成的。为了实现我们的目标，我们将使用细胞培养、体外测试和小鼠模型进行实验。鉴于将老年性黄斑变性(AMD)与炎症过程联系起来的遗传学发现，我们将研究双维A酸类RPE脂褐素色素的光氧化产物作为补体的激活剂，补体是免疫途径的一种元素(目标1)。这些研究涉及与AMD相关的四个因素：炎症、氧化损伤、玻璃体和RPE脂褐素。我们还将比较已知的脂褐素成分对光产生氧的活性形式和光诱导的切割的倾向(目标2)。在与最佳卵黄样黄斑营养不良和其他VMD2相关疾病相关的研究中，我们将探索这样的假设，即VMD2的蛋白质产物Bestrophin-1功能障碍会改变细胞内氯电导，从而改变RPE脂褐素系列全跨视网膜二聚体系列的质子化/共轭和非质子化/非结合形式之间的光氧化速率和平衡。我们认为，平衡的转变有利于RPE脂褐素成分(非结合的全跨视网膜二聚体)，它是含醛的，更具光反应性(目标3)。公共卫生相关性：国家眼科研究所将提高对黄斑变性的分子和生化基础的了解作为一个5年的计划目标。AMD在美国影响着超过175万人。根据1/10,000的患病率，另有30,000名美国人患有Stargardt病。由于人口老龄化的趋势，到2020年，AMD的病例数量可能会增加到300万。更深入地了解个别RPE脂褐素色素的特性和特性、它们的不良行为以及影响它们形成的因素，将有助于出现新的治疗方法，以最大限度地减少脂褐素积聚和/或中和其影响，从而减少黄斑变性的发生率和进展。

DESCRIPTION (provided by applicant): The proposed research program endeavors to advance our understanding of the mechanisms by which the lipofuscin that accumulates in retinal pigment epithelial cells (RPE) contributes to disease processes in atrophic macular degeneration, including age-related and juvenile (Stargardt disease and Best vitelliform macular dystrophy) forms. The lipofuscin of RPE cells originates primarily in photoreceptor cells and is generated, in large part, from reactions of all-trans-retinal, which forms when visual pigment absorbs photons of light. To achieve our objectives, we will conduct experiments using cell culture, in vitro assays and mouse models. In light of genetic discoveries linking age-related macular degeneration (AMD) to inflammatory processes, we will investigate photooxidation products of bisretinoid RPE lipofuscin pigments as activators of complement, an element of immune pathways (Aim 1). These studies address four factors posited as being associated with AMD: inflammation, oxidative damage, drusen and RPE lipofuscin. We will also compare known lipofuscin constituents in terms of their propensity for photo-generating reactive forms of oxygen and for photo-induced cleavage (Aim 2). In studies related to Best vitelliform macular dystrophy and other VMD2-associated disorders, we will explore the hypothesis that dysfunctioning of bestrophin-1, the protein product of VMD2, alters intracellular chloride conductances thereby changing pH-dependent rates of photooxidation and equilibria between protonated/conjugated and unprotonated/unconjugated forms of the all-trans-retinal dimer series of RPE lipofuscin pigments. We propose that the shift in equilibrium favors an RPE lipofuscin constituent (unconjugated all-trans-retinal dimer) that is aldehyde-bearing and more photoreactive (Aim 3). PUBLIC HEALTH RELEVANCE: The National Eye Institute has as a 5-year program goal, improved understanding of the molecular and biochemical basis of macular degeneration. AMD affects more than 1.75 million people in the United States. Based on a prevalence of 1/10,000, an additional 30,000 Americans are afflicted with Stargardt disease. Due to the trend toward population aging, the number of cases of AMD could increase to 3 million by 2020. Greater insight into the identities and properties of individual RPE lipofuscin pigments, their adverse behaviors and the factors that influence their formation will facilitate the emergence of novel therapeutic approaches to minimize lipofuscin accumulation and/or neutralize its impact, and thus reduce the incidence and progression of macular degeneration.