Recognition of fibrinogen by leukocyte integrins

白细胞整合素对纤维蛋白原的识别

• 批准号: 6917095
• 负责人: Tatiana P Ugarova
• 金额: $ 30.6万
• 依托单位: CLEVELAND CLINIC LERNER COM-CWRU
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-07-01 至 2009-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6917095
• 关键词: binding sites; cell adhesion; cell migration; clinical research; extracellular matrix; fibrinogen; genetically modified animals; human subject; inflammation; integrins; intermolecular interaction; laboratory mouse; leukocytes; ligands; neutrophil; phage display; protein binding; protein sequence; site directed mutagenesis

DESCRIPTION (provided by applicant): Integrin-alpha-M-beta-2 (CD11b/CD18, Mac-l) plays a pivotal role in the inflammatory response and host defense. By mediating critical adhesive reactions of neutrophils it participates in regulating neutrophil influx to the sites of inflammation and initiates numerous neutrophil responses. This receptor is also a potential therapeutic target in many diseases in which the inflammatory component plays an essential role. Alpha-M-beta-2 exerts its functions by binding a multitude of biologically diverse molecules. However, the mechanism which allows alpha-Mbeta-2 to exhibit broad specificity and the biological value of alpha-M-beta-2 ligand promiscuity are not known. Our long term goal is to understand the molecular basis for ligand recognition by alpha-M-beta-2, and to determine how alpha-M-beta-2 ligand promiscuity affects its adhesive functions. Studies over the past funding period have mapped the alpha-M-beta-2-binding site in the physiologically important ligand fibrinogen, and identified the recognition peptide that effectively disrupted alpha-M-beta-2-mediated cell adhesion not only to fibrinogen but also to many other ligands. Based on these findings, we have hypothesized that the fibrinogen recognition motif contains critical structural information required for alpha-M-beta-2 binding and that it may serve as a prototype adhesive signal in many alpha-M-beta-2 ligands. We will test this hypothesis by analyzing alpha-M-beta-2-binding sites in fibrinogen and in other physiological ligands using combinatorial peptide libraries and mutational analyses of fibrinogen domains. We will also use phage display to delineate the general principles that control alpha--beta-2 ligand recognition. Our data further indicated that a discrete region in the alpha-M-I-domain of alpha-M-beta-2 participates in binding of numerous ligands which has led us to propose the hypothesis that the unique region in the alpha-M-I-domain constitutes the consensus binding site for recognition of many ligands. Through the use of chimeric and point mutations between alpha-M-beta-2 and alpha-L-beta-2, the related beta-2 integrin with a different ligand specificity, we will determine the structural features required for the interaction of the consensus binding site with multiple ligands. Finally, the impact of alpha-M-beta-2's multi-ligand binding potential on its adhesive functions will be studied. We hypothesize that the alpha-M-beta-2 ability to be upregulated to high density on the surface of neutrophils and its capacity to engage numerous ligands in the extracellular matrix may modulate general cell adhesiveness and, thus, stop neutrophil migration at the site of inflammation. We will test this hypothesis by manipulating alpha-M-beta-2 expression on the surface of neutrophils and will also use neutrophils with alpha-M-beta-2 deficiency. Together, these studies will provide important insights into the structural basis of alpha-m-beta-2 ligand binding and define the mechanism by which alpha-M-beta-2 binding promiscuity controls leukocyte adhesive functions. Thus, these studies may lead to an increased understanding of the principles that govern ligand recognition by integrins and will be useful in the design of novel therapeutic agents to specifically disrupt alpha-M-beta-2-ligand interactions

描述（由申请人提供）：整合素-α-M-β-2（CD 11b/CD 18，Mac-1）在炎症反应和宿主防御中起关键作用。通过介导中性粒细胞的关键粘附反应，它参与调节中性粒细胞流入炎症部位并启动许多中性粒细胞反应。该受体也是许多疾病的潜在治疗靶点，其中炎症组分起着重要作用。α-M-β-2通过结合多种生物多样性分子来发挥其功能。然而，允许α-M-β-2表现出广泛特异性的机制和α-M-β-2配体混杂的生物学价值尚不清楚。我们的长期目标是了解alpha-M-beta-2配体识别的分子基础，并确定alpha-M-beta-2配体混杂如何影响其粘附功能。在过去的资助期间的研究已经绘制了生理学上重要的配体纤维蛋白原中的α-M-β-2-结合位点，并鉴定了有效破坏α-M-β-2-介导的细胞粘附的识别肽，不仅与纤维蛋白原，而且与许多其他配体。基于这些发现，我们假设纤维蛋白原识别基序包含α-M-β-2结合所需的关键结构信息，并且它可能在许多α-M-β-2配体中充当原型粘附信号。我们将测试这一假设，通过分析α-M-β-2-纤维蛋白原结合位点和其他生理配体使用组合肽库和突变分析的纤维蛋白原结构域。我们还将使用噬菌体展示来描述控制α-β-2配体识别的一般原理。我们的数据进一步表明，在α-M-β-2的α-M-I-结构域中的离散区域参与许多配体的结合，这使我们提出了这样的假设，即α-M-I-结构域中的独特区域构成了识别许多配体的共有结合位点。通过使用α-M-β-2和α-L-β-2之间的嵌合突变和点突变，相关的β-2整联蛋白具有不同的配体特异性，我们将确定共有结合位点与多个配体相互作用所需的结构特征。最后，将研究α-M-β-2的多配体结合潜力对其粘附功能的影响。我们推测，α-M-β-2在中性粒细胞表面上调至高密度的能力及其与细胞外基质中众多配体结合的能力可能调节一般细胞增殖，从而阻止中性粒细胞在炎症部位的迁移。我们将通过操纵中性粒细胞表面的α-M-β-2表达来检验这一假设，也将使用α-M-β-2缺陷的中性粒细胞。总之，这些研究将提供重要的见解的α-M-β-2配体结合的结构基础，并确定α-M-β-2结合混杂控制白细胞粘附功能的机制。因此，这些研究可能导致对整合素调控配体识别的原理的理解增加，并且将用于设计新的治疗剂以特异性破坏α-M-β-2-配体相互作用