Regulation of Atopic Immune Responses by the Prolyl lsomerase Cyclophillin A

脯氨酰异构酶亲环蛋白 A 对特应性免疫反应的调节

• 批准号: 7017421
• 负责人: JOHN D COLGAN
• 金额: $ 36.88万
• 依托单位: UNIVERSITY OF IOWA
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-03-15 至 2011-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7017421
• 关键词: asthma; cytokine; gene mutation; hypersensitivity; immune response; mutant; role

DESCRIPTION (provided by applicant): Asthma and other allergic diseases are widespread health problems for industrialized nations. In order to develop therapeutic agents that lessen the severity of these diseases, the biological processes that drive allergy need to be defined. Allergic reactions are triggered by excessive helper T cell responses to antigens; thus these cells are attractive targets for new therapeutics. The long-term objective of this proposal is to define specific intracellular signaling events within helper T cells that control the production of allergy- promoting cytokines such as IL-4. We have identified an important role for the cyclosporine receptor cyclophilin A (CypA) in regulating helper T cell responses. CypA alters the structure of peptide bonds adjacent to proline residues, and may thus regulate protein function by inducing conformational changes. Mice lacking CypA develop inflammation that contains eosinophils and mast cells, two cell types that have key roles in allergic responses. Helper T cells from these mice overproduce IL-4 and other allergy- associated cytokines and show increased activation of the key signaling molecule phospholipase C-gamma1 (PLCgl). A known regulator of PLCgl is Itk, a tyrosine kinase that controls IL-4 expression. CypA interacts with a proline residue in Itk ; this interaction promotes Itk self-association, which is postulated to downregulate Itk activity, and also inhibits contacts between Itk and other factors that promote PLCgl activation. Based on these findings, our central hypothesis is that CypA functions as represser of Itk activity, thus limiting IL-4 expression by helper T cells. To explore this hypothesis, we will pursue the following specific aims: 1) Identify amino acids that are required for interaction between Itk and CypA and for Itk self- association; biochemical assays will be used to assess how amino acid changes in Itk and CypA affect protein-protein interactions; 2) Determine the effects of mutations in CypA and Itk on function; CypA and Itk mutant proteins with altered function will be expressed in helper T cells to assess their impact on IL-4 expression and PLCgl activation; 3) Determine the role of CypA and Itk in allergic disease; how changes in CypA or Itk activity modulate asthma development in mouse model for this disease will be analyzed; 4) Determine whether CypA regulates the development of helper T cells that express allergy-promoting cytokines; a cell culture system will be used to define regulatory targets for CypA.

描述(申请人提供)：哮喘和其他过敏性疾病是工业化国家普遍存在的健康问题。为了开发减轻这些疾病严重程度的治疗剂，需要定义导致过敏的生物过程。过敏反应是由辅助性T细胞对抗原的过度反应引发的，因此这些细胞是新疗法的有吸引力的靶点。这项建议的长期目标是确定辅助T细胞内控制IL-4等促过敏细胞因子产生的特定细胞内信号事件。我们已经确定了环孢素受体亲环素A(CypA)在调节辅助性T细胞反应中的重要作用。CypA改变了与Pro残基相邻的多肽键的结构，从而可能通过诱导构象变化来调节蛋白质的功能。缺乏CypA的小鼠会出现含有嗜酸性粒细胞和肥大细胞的炎症，这两种细胞类型在过敏反应中起关键作用。这些小鼠的辅助T细胞过度产生IL-4和其他与过敏相关的细胞因子，并显示出关键信号分子磷脂酶C-伽马1(PLCgl)的激活增加。已知的PLCgl调节因子是ITK，它是一种控制IL-4表达的酪氨酸激酶。CypA与ITK中的一个脯氨酸残基相互作用；这种相互作用促进了ITK的自结合，这被认为是下调ITK活性的，也抑制了ITK与其他促进PLCg1激活的因子之间的接触。基于这些发现，我们的中心假设是CypA作为ITK活性的抑制因子，从而限制辅助性T细胞表达IL-4。为了探索这一假设，我们将追求以下具体目标：1)确定ITK和CypA之间相互作用和ITK自我结合所需的氨基酸；将使用生化分析来评估ITK和CypA中的氨基酸变化如何影响蛋白质-蛋白质相互作用；2)确定CypA和ITK突变对功能的影响；CypA和ITK突变蛋白将在辅助T细胞中表达，以评估它们对IL-4表达和PLCg1激活的影响；3)确定CypA和ITK在过敏性疾病中的作用；CypA或ITK活性的变化如何调节哮喘的小鼠模型；4)确定CypA是否调节表达促过敏细胞因子的辅助性T细胞的发育；将使用细胞培养系统来确定CypA的调节靶点。