Structure-function studies on IL-18, IL-18 binding proteins and receptors

IL-18、IL-18 结合蛋白和受体的结构功能研究

• 批准号: 7893102
• 负责人: Junpeng Deng
• 金额: $ 32.96万
• 依托单位: OKLAHOMA STATE UNIVERSITY STILLWATER
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-01 至 2013-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7893102
• 关键词: Adopted; Affinity; Agonist; Amino Acid Sequence; Autoimmune Process; Binding; Biochemical; Biological Assay; Bioterrorism; Bypass; Cell surface; Cells; Cellular biology; Collection; Communicable Diseases; Complex; Cowpox; Crohn' s disease; Crystallography; Cytokine Receptors; Development; Dimensions; Dimerization; Disease; Down-Regulation; Extracellular Domain; Family; Feedback; Goals; Homologous Gene; Host Defense; Human; IL18 gene; Immune response; Immunotherapy; In Vitro; Inflammatory; Interleukin-1; Interleukin-1 Receptors; Interleukin-18; Knowledge; Lead; Ligand Binding; Malignant Neoplasms; Mediating; Medical; Methods; Microbe; Modeling; Molecular; Molluscum contagiosum virus; Mouse Pox Virus; Mutagenesis; Pathogenesis; Pathway interactions; Physiological; Play; Positioning Attribute; Poxviridae; Proteins; Receptor Activation; Recruitment Activity; Research; Resolution; Rheumatoid Arthritis; Role; Septic Shock; Signal Transduction; Site-Directed Mutagenesis; Smallpox; Smallpox Viruses; Structure; Surface Plasmon Resonance; Surface Properties; Therapeutic; Variant; Viral; Virus Diseases; base; combat; cytokine; design; human disease; in vivo; inhibitor/antagonist; insight; interleukin-18 binding protein; interleukin-18 receptor; molecular recognition; mutant; novel therapeutics; protein complex; public health relevance; receptor; receptor binding

DESCRIPTION (provided by applicant): Interleukin-18 (IL-18) is a pro-inflammatory cytokine that belongs to the interleukin-1 (IL-1) superfamily. It plays an important role in host defense against microbes but also contributes to pathogenesis of several inflammatory diseases, including rheumatoid arthritis, septic shock and Crohn's disease. IL-18 signaling is initiated by its cell-surface binding to the receptor (IL-18R) alpha subunit, followed by the recruitment of the receptor beta subunit to form a ternary signaling complex. IL-18 activities are regulated in vivo by a naturally occurring antagonist, the IL-18 binding protein (IL-18BP) through a negative feedback mechanism. Poxviruses, including the smallpox (variola) virus, also express functional IL-18BP homologues to evade IL-18-mediated host immune responses. IL-18, IL-18R and IL-18BP are therefore attractive targets for developing therapeutics agonist inflammatory or infectious diseases where down- or up-modulating IL-18 activities is indicated. However, there is a lack of thorough understanding of how IL-18 activates its receptor and how IL-18BP inhibits IL-18. We propose to determine the crystal structures of various protein complexes of IL-18 with IL-18R or IL-18BP and perform functional studies based on the structural information. In addition, we will perform structure-based design of IL-18 variants that may either serve as a more effective cytokine capable of evading the neutralization of poxvirus IL-18BPs, or as a receptor antagonist capable of blocking IL-18 activities. Aim 1. To determine the molecular mechanism by which IL-18BPs neutralize IL-18. Aim 2. To determine the molecular mechanism by which IL-18 specifically recognizes 1 subunit of IL-18R. Aim 3. To determine the molecular mechanism by which IL-18 triggers the hetero-dimerization of IL-18R1 and 2 subunits. The objective of this application is the detailed characterization of a collection of IL-18 complexes by a combination of biophysical and biochemical methods, including x-ray crystallography, Surface Plasmon Resonance (SPR) and IL-18 bioassay. Accomplishing this objective is an important first step for achieving our long-term goal of understanding how IL-18 activates its receptors to initiate cell signaling and how this activity is regulated by IL-18BP.This research obtains/assumes extra dimensions. Since the targeted proteins are of significant medical relevance, our studies will provide a platform for designing selective inhibitors that may ultimately be developed into new therapeutics against a number of human diseases. Public Health Relevance: Our contribution here is expected to provide detailed molecular recognition of IL-18 by IL-18BP and IL-18R. This contribution is significant because it will fill the gap of our current knowledge on IL-18 activation pathway, and will provide important clues on how to modulate IL-18 activity. It may benefit efforts in developing treatments against some autoimmune and inflammatory diseases, in developing immunotherapies against other infectious diseases and cancer and in combating bioterrorism.

描述（由申请人提供）：白细胞介素18（IL-18）是一种促炎细胞因子，属于白细胞介素1（IL-1）超家族。它在宿主抵御微生物方面发挥着重要作用，但也有助于多种炎症性疾病的发病机制，包括类风湿性关节炎、脓毒性休克和克罗恩病。 IL-18 信号传导是通过其细胞表面与受体 (IL-18R) α 亚基的结合启动的，然后招募受体 β 亚基形成三元信号传导复合物。 IL-18 活性在体内由天然存在的拮抗剂 IL-18 结合蛋白 (IL-18BP) 通过负反馈机制调节。痘病毒，包括天花病毒，也表达功能性 IL-18BP 同源物以逃避 IL-18 介导的宿主免疫反应。因此，IL-18、IL-18R 和 IL-18BP 是开发治疗激动剂炎症或感染性疾病的有吸引力的靶点，其中需要下调或上调 IL-18 活性。然而，对于IL-18如何激活其受体以及IL-18BP如何抑制IL-18还缺乏透彻的了解。我们建议确定IL-18与IL-18R或IL-18BP的各种蛋白质复合物的晶体结构，并根据结构信息进行功能研究。此外，我们将对 IL-18 变体进行基于结构的设计，这些变体可以作为能够逃避痘病毒 IL-18BP 中和的更有效的细胞因子，或者作为能够阻断 IL-18 活性的受体拮抗剂。目标 1. 确定 IL-18BP 中和 IL-18 的分子机制。目的 2. 确定 IL-18 特异性识别 IL-18R 1 个亚基的分子机制。目标 3. 确定 IL-18 触发 IL-18R1 和 2 亚基异二聚化的分子机制。本应用的目的是通过生物物理和生化方法（包括 X 射线晶体学、表面等离子共振 (SPR) 和 IL-18 生物测定）相结合来详细表征一系列 IL-18 复合物。实现这一目标是实现我们了解 IL-18 如何激活其受体以启动细胞信号传导以及这种活动如何受 IL-18BP 调节的长期目标的重要第一步。这项研究获得/假设了额外的维度。由于目标蛋白具有重要的医学意义，我们的研究将为设计选择性抑制剂提供一个平台，最终可能开发成针对多种人类疾病的新疗法。公共卫生相关性：我们在此的贡献预计将提供 IL-18BP 和 IL-18R 对 IL-18 的详细分子识别。这一贡献意义重大，因为它将填补我们目前对 IL-18 激活途径知识的空白，并将为如何调节 IL-18 活性提供重要线索。它可能有利于开发针对某些自身免疫性疾病和炎症性疾病的治疗方法、开发针对其他传染病和癌症的免疫疗法以及打击生物恐怖主义。