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，许多疾病（包括自身免疫性疾病和癌症）与N-聚糖的组成变化相关。细胞表面受体特异性识别多种N-聚糖，这些相互作用可能在这些疾病中发挥关键作用。本研究的长期目标是探索N-聚糖的结构和动力学，如连接到蛋白质和蛋白质-蛋白质相互作用中的特定协调。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RA和免疫球蛋白G（IgG）的特定posterodynamically修饰形式之间的联系提供了一个重要的关键，了解疾病，并找到一个更有效的治疗。该修饰涉及与IgG的Fc片段连接的双触角N-聚糖的末端唾液酸化。发现这种特异性修饰显著增加IgG的抗炎活性，表明唾液酸化Fc聚糖的分子模拟物可能是RA的有希望的新治疗。本研究的目的是：1）利用核磁共振（NMR）技术研究末端唾液酸残基的分子特征以及唾液酸化对IgG Fc片段相关N-聚糖的影响; 2）开发用于分配N-连接聚糖共振的技术。这将利用Aim 1的1 - 3 C-标记策略与新的质谱分析技术相结合，以将共振与这些复合型N-聚糖的α 1 -3或α 1 -6分支相关联; 3）计算N-聚糖末端的唾液酸-半乳糖二糖的结构并评价其动力学;和4）测量唾液酸化的Fc片段与其提出的受体树突细胞特异性ICAM-3-抓取非整联蛋白（DC-SIGN）的相互作用。 公共卫生相关性：风湿性关节炎是一种使人衰弱的疾病，限制了受影响个体的健康和生产力。这项建议将利用最近的科学发现，研究类风湿性关节炎的分子相互作用的细节。这些知识将指导未来开发更有效的类风湿关节炎治疗方法。

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.