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: 8461947
• 负责人: Goldis Malek
• 金额: $ 36.48万
• 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/8461947
• 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.

描述（由申请人提供）：视网膜下色素上皮（sub-RPE）沉积物形成的细胞和分子途径尚不清楚，该沉积物是年龄相关性黄斑变性（AMD）早期“干性”形式的标志，也是老年人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) 饮食摄入量和氧化损伤是 AMD 的风险。此外，包括我们自己的实验室在内的多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沉积物形成中发挥着关键作用。然而，多不饱和脂肪酸的膳食摄入量与促进沉积物形成的信号通路之间的联系尚不清楚。因此，我们的目标是确定脂质（包括多不饱和脂肪酸）调节沉积物形成的致病机制。 过氧化物酶体增殖物激活受体 (PPAR) 是充当脂质传感器的核受体。在这三种异构体中，PPAR/d 介导膳食脂肪酸（包括 n-6 PUFA）对基因表达的调节作用，并刺激过氧化物酶体（参与脂肪酸氧化的细胞器）的增殖。 PPAR 转录活性与胆固醇和脂质流出、细胞外基质 (ECM) 合成改变和线粒体功能障碍相关分子的上调相结合；这些分子家族也与沉积物的形成有关。考虑到这一点，我们提出了一个推论问题：RPE 细胞中 PPAR¿/d 信号通路的饮食脂质激活是否会刺激沉积物形成？ 在我们的初步研究中，我们发现将 RPE 细胞培养物暴露于 n-6 PUFA 的天然和氧化衍生物会导致与沉积物形成相关并调节沉积物形成的分子表达发生深刻的细胞变化。这些变化包括（1）ECM分子胶原IV的合成和分泌增加； (2)胆固醇和脂质流出调节基因ABCA1和CD36表达增加； (3)受损线粒体和活性氧的积累； (4)激活PPAR ¿/d； (5)上调调节ECM分子和脂质分泌的PPARk/d特异性靶基因。 基于这些初步数据，我们假设膳食 n-6 脂肪酸通过激活 PPARk/d 和增加过氧化物酶体的增殖来刺激沉积物中分子的产生。沉积物的积累需要 RPE 分泌脂质和胆固醇，并且 RPE 合成 ECM 分子失调，导致脂质滞留。我们进一步提出，PPAR/d 通路上的额外“压力源”（即年龄、氧化剂）会导致这些过程的上调，并进一步损害由线粒体功能障碍介导的 RPE 细胞功能。为了检验这一假设，我们将结合使用人类 RPE 细胞和​​小鼠沉积物模型的细胞培养测定来研究 PPAR 在沉积物形成中的作用。我们还将研究降低 PPAR/d 的活性是否可以减缓沉积物形成小鼠模型中 AMD 的进展。