NMR Studies on the Structure and Dynamics of Glycan-Mediated IgG Interactions

描述（由申请人提供）：n -连接蛋白糖基化是最常见的真核蛋白修饰，包括自身免疫性疾病和癌症在内的许多疾病都与n -聚糖的组成改变有关。广泛的n -聚糖被细胞表面受体特异性识别，这些相互作用可能在这些疾病中起关键作用。本研究的长期目标是探索n-聚糖附着在蛋白质上的结构和动力学，并在蛋白质-蛋白质相互作用中进行特异性协调。类风湿性关节炎（RA）是一种自身免疫性疾病，是一种致残性疾病，可以在任何年龄发作，通过破坏关节组织使患者致残和毁容。最近，一种特定的翻译后修饰的免疫球蛋白G （IgG）与类风湿关节炎之间的联系为了解这种疾病和寻找更有效的治疗方法提供了重要的关键。这种修饰涉及到附着在IgG Fc片段上的双触角n聚糖的末端唾液酰化。这种特异性修饰可显著提高IgG的抗炎活性，提示唾液化Fc聚糖的分子模拟物可能是治疗RA的一种有希望的新方法。本研究的目的是：1)利用核磁共振（NMR）技术研究唾液酸末端残基的分子特征以及唾液酰化对IgG Fc片段相关n -聚糖的影响；2)开发n链聚糖共振分配技术。这将利用Aim 1的13c标记策略结合一种新的质谱分析技术来关联这些复杂型n -聚糖的α 1-3或α 1-6分支的共振；3)计算n -聚糖末端的唾液酸-半乳糖双糖的结构并评价其动力学；4)测量唾液化Fc片段与其提出的受体，树突状细胞特异性icam -3捕获非整合素（DC-SIGN）的相互作用。

DESCRIPTION (provided by applicant): N-linked protein glycosylation is the most common eukaryotic protein modification and many diseases including autoimmune disorders and cancer are associated with compositional changes of N-glycans. A broad spectrum of N-glycans are specifically recognized by cell surface receptors, and these interactions likely play a critical role in these diseases. The long-term goals of this research are to explore the structure and dynamics of N-glycans as attached to a protein and as specifically coordinated in a protein-protein interaction. Rheumatoid arthritis (RA), an autoimmune disorder, is a crippling disease that can strike at any age, disabling and disfiguring its victims by destroying joint tissue. A recent link between RA and a specific posttranslationally modified form of immunoglobulin G (IgG) provides an important key to understanding the disease and finding a more effective treatment. The modification involves terminal sialylation of the biantennary N-glycans attached to the Fc fragment of IgG. This specific modification is found to dramatically increase the anti-inflammatory activity of IgG, suggesting molecular mimics of the sialylated Fc glycans may be a promising new treatment for RA. The aims of this proposal are: 1) To study the molecular character of terminal sialic acid residues and the effect of sialylation on the N-glycans associated with the Fc fragment of IgG using nuclear magnetic resonance (NMR)-based techniques; 2) To develop techniques for the assignment of N-linked glycan resonances. This will utilize the 13C-labeling strategy of Aim 1 combined with a novel mass spectral analysis technique to correlate resonances with either the alpha1-3 or alpha1-6 branch of these complex-type N-glycans; 3) To calculate a structure and evaluate the dynamics of the sialic acid-galactose disaccharides at the termini of the N-glycan; and 4) To measure the interaction of the sialylated Fc fragment with its proposed receptor, dendritic cell-specific ICAM-3-grabbing nonintegrin (DC-SIGN). PUBLIC HEALTH RELEVANCE: Rheumatoid arthritis is a debilitating disease that limits the health and productivity of affected individuals. This proposal will utilize recent scientific discoveries to study the details of molecular interactions underlying rheumatoid arthritis. This knowledge will guide the future development of more effective treatments of rheumatoid arthritis.