Lipid Activated Nuclear Receptors in Age-Related Macular Degeneration

年龄相关性黄斑变性中的脂质激活核受体

• 批准号: 8258719
• 负责人: Goldis Malek
• 金额: $ 39.85万
• 依托单位: DUKE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-05-01 至 2016-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8258719
• 关键词: Affect; Age; Age related macular degeneration; Animal Model; Biogenesis; Biological Assay; Blindness; CD36 gene; Cell Culture Techniques; Cell physiology; Cells; Cellular Metabolic Process; Cholesterol; Clinical; Collagen Type IV; Coupled; Data; Deposition; Development; Diet; Dietary Fats; Dietary Fatty Acid; Dietary intake; Disease; Elderly; Epithelial; Extracellular Matrix; Family; Fatty Acids; Functional disorder; Gene Expression; Gene Targeting; Genes; Goals; Grant; Human; In Vitro; Individual; Injury; Laboratories; Lead; Ligands; Link; Lipids; Lipoproteins; Mediating; Mind; Mitochondria; Modeling; Molecular; Mus; Nuclear Receptors; Organelles; Oxidants; Pathologic; Pathology; Pathway interactions; Peroxisome Proliferation; Peroxisome Proliferator-Activated Receptors; Phenotype; Play; Polyunsaturated Fatty Acids; Process; Production; Protein Isoforms; Proteins; Reactive Oxygen Species; Regulator Genes; Retinal Pigments; Risk; Risk Factors; Role; Signal Pathway; Testing; Therapeutic; Therapeutic Effect; Unsaturated Fatty Acids; Up-Regulation; Western World; base; design; epidemiology study; extracellular; fatty acid oxidation; in vivo; mitochondrial dysfunction; mouse model; particle; patient population; peroxisome; prevent; public health relevance; secretion process; sensor; stressor; therapeutic development

DESCRIPTION (provided by applicant): The cellular and molecular pathways of sub-retinal pigment epithelial (sub-RPE) deposit formation, the hallmark of the early 'dry' form of age-related macular degeneration (AMD), and the leading cause of vision loss in the elderly, are not known. Epidemiology studies have identified age, n-6 polyunsaturated fatty acid (PUFA) dietary intake and oxidant injury as risks for AMD. Further, studies from several laboratories, including our own, suggest that pathways regulating lipid and cholesterol processing and secretion play a pivotal role in deposit formation. However, the link between dietary intake of PUFAs and signaling pathways that promote production of deposits formation is not known. Our goal therefore is to identify the pathogenic mechanisms by which lipids, including PUFAs, regulate deposit formation. Peroxisome proliferator activating receptors (PPARs) are nuclear receptors that act as lipid sensors. Of the three isoforms, PPAR¿/d mediates the regulatory effects of dietary fatty acids, including n-6 PUFAs, on gene expression and stimulates the proliferation of peroxisomes, organelles involved in fatty acid oxidation. PPAR transcriptional activity is coupled with upregulation of molecules associated with cholesterol and lipid efflux, altered extracellular matrix (ECM) synthesis, and mitochondrial dysfunction; these families of molecules are also associated with deposit formation. With this in mind, we asked a corollary question: does dietary lipid activation of the PPAR¿/d signaling pathway in RPE cells stimulate deposit formation? In our preliminary studies, we found that exposure of RPE cell cultures to native and oxidized derivatives of n-6 PUFAs resulted in profound cellular changes in the expression of molecules associated with and regulating deposit formation. The changes included (1) increased synthesis and secretion of ECM molecule collagen IV; (2) increased expression of cholesterol and lipid efflux regulatory genes ABCA1 and CD36; (3) accumulation of damaged mitochondria and reactive oxygen species; (4) activation of PPAR ¿/d; and (5) upregulation of PPAR¿/d specific target genes regulating ECM molecules, and lipid secretion. Based on this preliminary data, we hypothesize that dietary n-6 fatty acids stimulate production of molecules found in deposits through activation of PPAR¿/d and increased proliferation of peroxisomes. Accumulation of deposits requires lipid and cholesterol secretion by the RPE and dysregulated synthesis of ECM molecules by the RPE, leads to trapping of lipids. We further propose that additional 'stressors' on the PPAR¿/d pathway (i.e., age, oxidants) lead to upregulation of these processes and further compromise RPE cell function, mediated by mitochondrial dysfunction. To test this hypothesis we will use a combination of cell culture assays with human RPE cells and mouse models of deposits to investigate the role of PPARs in deposit formation. We will also investigate if decreasing activity of PPAR¿/d can slow the progression of AMD in murine models of deposit formation. PUBLIC HEALTH RELEVANCE: Age-related macular degeneration (AMD) afects 30% of individuals over the age of 65 years and is the leading cause of vision loss in the Western World. Of the three clinical sub-types, the early 'dry' form of the disease effects over 85% of the patient population. Risk factors for developing the disease include advanced age, dietary intake of lipids and oxidant injury. The objective of this grant is to investigate signaling pathways used by dietary lipids that cause phenotypic pathology of early 'dry' AMD, specifically (1) production and accumulation of lipid and protein rich-extracellular deposits and (2) functional changes in lipid metabolic processing cellular organelles. We also propose to investigate the modulating effect of additional AMD risk factors, age and oxidant injury, on disease development. Currently there are no therapeutic options available for early 'dry' AMD. Understanding the mechanisms underlying deposit formation and identifying signaling pathways key to disease initiation and progression will open up new avenues for therapeutic strategies in early 'dry' AMD.

描述（由适用提供）：尚不清楚视网膜下皮（亚RPE）沉积物形成的细胞和分子途径，与年龄相关的黄斑变性（AMD）的早期“干”形式的标志，以及经常视力丧失的主要原因。流行病学研究已确定年龄，N-6多不饱和脂肪酸（PUFA）饮食摄入和氧化物损伤是AMD的风险。此外，来自包括我们自己的几个实验室的研究表明，调节脂质和胆固醇加工和分泌的途径在存款形成中起着关键作用。然而，尚不清楚PUFA的饮食摄入量与促进沉积物形成产生的信号通路之间的联系。因此，我们的目标是确定脂质（包括PUFAS）调节沉积物形成的致病机制。过氧化物体增殖物激活受体（PPAR）是充当脂质传感器的核受体。在这三种同工型中，PPAR¿ /D介导了包括N-6 Pufas在内的饮食脂肪酸对基因表达的调节作用，并刺激了参与脂肪酸氧化的细胞器的过氧化物体的增殖。 PPAR转录活性与与胆固醇和脂质外排相关的分子上调，细胞外基质（ECM）合成以及线粒体功能障碍的改变；这些分子家族也与沉积物形成有关。考虑到这一点，我们提出了一个必然的问题：RPE细胞中PPAR¿ /D信号通路的饮食脂质激活刺激了沉积的形成？在我们的初步研究中，我们发现RPE细胞培养物暴露于N-6 PUFA的天然和氧化衍生物，从而导致与调节沉积相关的分子表达和调节沉积形成的表达发生了深刻的细胞变化。变化包括（1）ECM分子胶原蛋白IV的合成和分泌增加； （2）胆固醇和脂质外排调节基因ABCA1和CD36的表达增加； （3）线粒体受损和活性氧的积累； （4）PPAR€ /D的激活； （5）PPAR¿ /D特定靶基因的上调，用于恢复ECM分子和脂质分泌。基于此初步数据，我们假设饮食中的N-6脂肪酸刺激通过激活PPAN /D的激活和增加过氧化物体的增殖而在沉积物中发现的分子的产生。沉积物的积累需要RPE的脂质和胆固醇分泌，并且RPE的ECM分子的合成失调会导致脂质捕获。我们进一步提出，在PPAR¿ /D途径（即年龄，氧化）上的其他“压力源”导致这些过程的上调，并进一步损害了RPE细胞功能，并由线粒体功能障碍介导。为了检验这一假设，我们将使用细胞培养测定与人RPE细胞和沉积小鼠模型的组合来研究PPAR在沉积形成中的作用。我们还将调查PPAR® /D的减少活性是否可以减慢沉积物形成的鼠模型中AMD的进展。 公共卫生相关性：与年龄相关的黄斑变性（AMD）影响65岁以上的30％的个体，这是西方世界视力丧失的主要原因。在这三种临床亚型中，疾病的早期“干”形式影响超过85％的患者人群。发展疾病的危险因素包括高龄，脂质饮食摄入和氧化剂损伤。该赠款的目的是研究引起早期“干” AMD表型病理学的饮食脂质使用的信号传导途径，特别是（1）（1）脂质和蛋白质富含蛋白质的细胞沉积物的产生和积累，以及（2）脂质代谢加工细胞器细胞器的功能变化。我们还建议研究其他AMD危险因素，年龄和氧化剂损伤对疾病发展的调节作用。目前，没有用于早期“干” AMD的治疗选择。了解形成沉积物的基础机制并识别信号通路的疾病开始和进展的关键将为早期“干” AMD的治疗策略开辟新的途径。