Structure and Function of Serum Amyloid A in Health and Disease

血清淀粉样蛋白 A 在健康和疾病中的结构和功能

基本信息

批准号：
10321653
负责人：
Olga Gursky
金额：
$ 31.35万
依托单位：
BOSTON UNIVERSITY MEDICAL CAMPUS
依托单位国家：
美国
项目类别：
财政年份：
2020
资助国家：
美国
起止时间：
2020-01-01 至 2023-12-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10321653
关键词：
Acute Acute-Phase Proteins Address Affect Amyloid Amyloid beta-Protein Precursor Amyloidosis Anabolism Autoimmune Diseases Binding Biochemical Biological Markers Biophysics Blood CD36 gene Calorimetry Cell membrane Cells Cellular Membrane Cholesterol Chronic Circular Dichroism Clear Cell Complement Complex Complication Coupled Data Deposition Deuterium Disease Docking Drops Electron Microscopy Evolution Excision Face Fluorescence Future Health Heparin Heparitin Sulfate High Density Lipoprotein Cholesterol High Density Lipoproteins Homeostasis Hour Hydrogen Hydrophobic Surfaces Immune response Infection Inflammation Injury Kinetics Life Ligand Binding Ligands Lipid Binding Lipids Lipoprotein Binding Lipoproteins Liver Malignant Neoplasms Mass Spectrum Analysis Membrane Lipids Methods Molecular Molecular Conformation Molecular Sieve Chromatography Natural Immunity Nonesterified Fatty Acids Organ Pathogenicity Pathologic Patients Phase Phospholipase A2 Phospholipids Pilot Projects Plasma Plasma Proteins Play Process Proteins Proteolysis Public Health Publishing Reaction Receptor Cell Research Resolution Role Serum Serum amyloid A protein Shapes Site Structural Models Structure Study of serum Sulfate Surface Testing Tissues Titrations Trauma Triglycerides Work acute infection amyloid formation base chronic infection healing human disease injured insight lipid metabolism lipophilicity lipoprotein triglyceride molecular dynamics new therapeutic target novel novel therapeutics preference receptor receptor binding repaired stem synergism therapeutic target

项目摘要

Abstract This research is focused on normal and pathologic actions of serum amyloid A (SAA), an enigmatic biomarker of inflammation and a protein precursor of AA amyloidosis, a life-threatening complication of chronic inflammation. SAA is a small soluble intrinsically disordered protein that increases rapidly and dramatically up to 1,000-fold in plasma following inflammation, infection or injury. The advantage for survival of this steep but transient increase is unclear, and the beneficial role of SAA in immune response is obscure. However, evolutionarily conserved aspects of the SAA structure, its lipophilic character, and the rapid and major commitment of liver and local tissues to SAA biosynthesis strongly support the importance of SAA-lipid interactions. Our new structural model suggests how SAA binds lipids and cell receptors, thereby rerouting lipid metabolism. Pilot biochemical studies compel us to propose a vital new role for SAA in clearing cellular membrane debris from the injured sites. Our powerful biophysical and biochemical approach will determine the mechanism via which SAA sequesters phospholipids and other lipids from cell membranes to facilitate their breakdown and safe removal from the injured sites in a process that is prerequisite for tissue healing. We will also determine how various lipids and other factors modulate amyloid formation by SAA, and thereby help decelerate or block this pathogenic process. Three complementary specific aims develop new concepts fundamental to SAA action in immune response and amyloid formation. Aim 1 will use an array of biophysical, structural and cell-based methods to establish molecular underpinnings for SAA interactions with its functional ligands, lipids and CD36 cell receptor. We will test our new structural model suggesting that SAA binds lipids via a unique apolar face whose shape defines protein's preference for binding to highly curved lipoproteins or forming them de novo to sequester lipids. We will determine the SAA conformation on the lipid and quantify its binding to CD36. Aim 2 will probe a novel synergy between SAA and secretory phospholipase A2 (sPLA2), an acute-phase plasma protein upregulated simultaneously with SAA in inflammation. Pilot studies compel us to propose a novel beneficial function of SAA in solubilizing phospholipids and their hydrolytic products to generate substrates for sPLA2 and to remove its products. The results will establish the hitherto unknown vital primordial role of SAA. Aim 3 will determine effects of various lipids, their degradation products, pH and heparin sulfate on SAA amyloid formation. We will also test our new idea that plasma lipids such as triacylglycerol modulate the SAA release from its major plasma carrier, high-density lipoprotein, and ultimately form amyloid. The results will help determine whether lipid-lowering therapies hold promise for treating AA amyloidosis. Completion of this research will establish raison d'etre for this enigmatic protein, provide a molecular basis for its action in immune response and lipid homeostasis, and help find much-needed new therapies or repurpose existing ones to treat a life-threatening human disease.

抽象的这项研究的重点是血清淀粉样蛋白A（SAA）的正常和病理作用，SAA（SAA）是一个神秘的生物标志物 AA淀粉样变性的炎症和蛋白质前体，这是慢性炎症的生命并发症。 SAA是一种固有无序蛋白的小型可溶性蛋白炎症，感染或损伤后血浆。这种陡峭但短暂的增加的生存优势尚不清楚，SAA在免疫反应中的有益作用是晦涩的。但是，进化保守 SAA结构的各个方面，其亲脂性特征以及肝脏和局部组织的快速而主要的承诺为了SAA生物合成强烈支持SAA-脂质相互作用的重要性。我们的新结构模型建议 SAA如何结合脂质和细胞受体，从而重新安装脂质代谢。试验生化研究迫使我们提出SAA在清除受伤部位清除细胞膜碎片方面的重要新作用。我们的强大生物物理和生化方法将确定SAA隔离磷脂的机制和其他脂质从细胞膜中促进其分解和安全从受伤部位的安全去除过程是组织愈合的先决条件。我们还将确定各种脂质和其他因素通过SAA调节淀粉样蛋白的形成，从而有助于减速或阻止这种致病过程。三个互补的特定目的制定了针对免疫反应和免疫反应行动的基础的新概念淀粉样蛋白形成。 AIM 1将使用一系列生物物理，结构和基于细胞的方法来建立 SAA相互作用与其功能性配体，脂质和CD36细胞受体相互作用的分子基础。我们将测试我们的新结构模型，这表明SAA通过独特的Apolol脸结合脂质，其形状定义蛋白质偏爱与高度弯曲的脂蛋白结合或将其从头形成隔离脂质。我们将确定脂质上的SAA构象并量化其与CD36的结合。 AIM 2将探究新颖的协同作用在SAA和分泌磷脂酶A2（SPLA2）之间，急性期等离子体蛋白上调同时与SAA发炎。试点研究迫使我们提出了SAA的新型有益功能溶解磷脂及其水解产物以生成SPLA2的底物并去除其产品。结果将确定SAA迄今未知的重要原始作用。 AIM 3将确定效果 SAA淀粉样蛋白形成的各种脂质，其降解产物，pH和硫酸肝素。我们还将测试我们的新想法是，诸如三酰基甘油等血浆脂质从其主要等离子体载体中调节SAA释放高密度脂蛋白，最终形成淀粉样蛋白。结果将有助于确定降低脂质是否降低疗法有望治疗AA淀粉样变性。这项研究的完成将建立Raison d'Etre 这种神秘的蛋白质为其在免疫反应和脂质稳态方面的作用提供了分子基础，以及帮助找到急需的新疗法或重新利用现有的疗法以治疗威胁生命的人类疾病。