Role of Immunoproteasomes in Activated T Cell Apoptosis

免疫蛋白酶体在活化 T 细胞凋亡中的作用

• 批准号: 7237115
• 负责人: THOMAS A GRIFFIN
• 金额: $ 18.75万
• 依托单位: CINCINNATI CHILDRENS HOSP MED CTR
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-20 至 2009-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7237115
• 关键词: Active Sites; Acute; Affect; Antigens; Apoptosis; Apoptotic; Autoimmune Diseases; Autoimmunity; CD8B1 gene; Catalytic Domain; Cell Death; Cell Survival; Cells; Clonal Expansion; Data; Development; Disease; Enterotoxins; Exhibits; Family; Family member; Future; Generations; Goals; Hand; Homeostasis; Immune; Immune response; Immunity; Immunologic Memory; Infection; Interferons; Knock-out; Knockout Mice; Lead; Lymphoid Cell; MHC Class I Genes; Malignant - descriptor; Malignant Neoplasms; Mediating; Mediator of activation protein; Memory; Minority; Molecular; Mus; Pathogenesis; Peptides; Phenotype; Play; Process; Proteasome Inhibition; Proteins; Rate; Regulation; Role; System; T-Lymphocyte; Testing; Time; Ubiquitin; Virus Diseases; Work; antigen processing; cell type; improved; in vivo; multicatalytic endopeptidase complex; mutant; novel; prevent; protein degradation; response; tumor

DESCRIPTION (provided by applicant): Clonal expansion of T cells in response to cognate antigen eventually leads to deletion of most of the expanded T cells via programmed cell death (apoptosis), with only a minority surviving to become memory cells. This process is crucial for restoring T cell homeostasis after termination of an acute immune response, which promotes protective immunity and deters autoimmunity. While there is now strong evidence that proteins of the Bcl-2 family, particularly anti-apoptotic Bcl-2 and pro-apoptotic Bim, play an important role in mediating apoptosis of T cells activated in vivo, little is known about how these proteins themselves are controlled. One mechanism by which Bcl-2 family members may be regulated is ubiquitin/proteasome-mediated degradation. T cells have specialized proteasomes called "immunoproteasomes" that contain three interferon-g-inducible catalytic immunosubunits: LMP2, LMP7 and MECL-1. We have recently observed that T cells from immunoproteasome-deficient mice lacking both MECL-1 and LMP7 exhibit exaggerated apoptosis after in vivo activation by super-antigen. Conversely, over-expression of LMP7 in normal super-antigen activated T cells significantly suppresses apoptosis. Taken together, these results suggest that immunoproteasomes play a role in regulating the magnitude of apoptosis of activated T cells. Given the central role of Bcl-2 family members in mediating activated T cell apoptosis, and that several Bcl-2 family members are proteasome substrates, we hypothesize that immunoproteasomes regulate the magnitude of Bim-driven apoptosis of activated T cells through degradation of Bcl-2 family members. We will investigate this hypothesis in the following specific aims: 1. Determine the role of immunoproteasomes in the degradation and function of pro-apoptotic Bcl-2 family members. This aim will involve the generation of triple knockout mice (Bim-/-/MECL- 1-/-/LMP7-/-) to determine if Bim is required for the pro-apoptotic effect of immunoproteasome deficiency, and this aim will also assess the impact of immunoproteasome deficiency on the function and degradation of pro- apoptotic Bcl-2 family members in activated T cells. 2. Identify structural and functional features of immunoproteasomes that are critical for their anti-apoptotic activity. This aim will involve testing the ability of active site and assembly mutants of LMP7 and related proteasome subunits to modulate apoptosis of activated T cells, and determine whether immunoproteasome expression in normal activated T cells correlates with apoptotic activity. In the long-term, elucidation of molecular mechanisms underlying the role of immunoproteasomes in activated T cell apoptosis will further our understanding of the development of immune memory, and potentially identify targets for enhancing apoptosis of auto-reactive T cells involved in the pathogenesis of autoimmune disease, or suppressing apoptosis of T cells that could contribute to control of infectious or malignant disease. An immune response to a "threat" (such as infection or tumor) must be controlled in such a way as to provide memory to protect from similar threats in the future (immunity), while at the same time preventing unwanted damage to one's self (autoimmunity). The goal of this project is to improve our understanding of the molecules that participate in this control system, which could lead to better treatments of diseases in which this system is self-defeating or breaks down (infections, cancer, or autoimmune disease).

描述（由申请人提供）：响应于同源抗原的T细胞的克隆扩张最终导致大多数通过程序性细胞死亡（凋亡）删除大多数扩张的T细胞，只有少数族裔幸存下来成为记忆细胞。此过程对于终止急性免疫反应后恢复T细胞稳态至关重要，这促进了保护性免疫并阻止自身免疫性。尽管现在有充分的证据表明，Bcl-2家族的蛋白质，尤其是抗凋亡的Bcl-2和促凋亡BIM，在介导体内激活的T细胞凋亡中起着重要作用，但对这些蛋白质本身的控制知之甚少。 Bcl-2家族成员可以调节的一种机制是泛素/蛋白酶体介导的降解。 T细胞具有称为“免疫蛋白酶体”的专门蛋白酶体，其中包含三个干扰素-G诱导的催化免疫吸收：LMP2，LMP7和MECL-1。我们最近观察到，超级抗原在体内激活后，缺乏MECL-1和LMP7的免疫蛋白酶体缺乏小鼠的T细胞均显示出夸张的细胞凋亡。相反，正常超抗原激活的T细胞中LMP7的过表达显着抑制了凋亡。综上所述，这些结果表明免疫蛋白酶体在调节活化T细胞凋亡的大小中起作用。鉴于Bcl-2家族成员在介导活化的T细胞凋亡中的核心作用，并且几个Bcl-2家族成员是蛋白酶体底物，我们假设免疫蛋白酶体通过降解BCL-2家族成员的降解来调节BIM驱动T细胞的BIM驱动T细胞的大小。我们将在以下具体目的中研究这一假设：1。确定免疫蛋白酶体在促凋亡Bcl-2家族成员的降解和功能中的作用。这个目标将涉及产生三重基因敲除小鼠（BIM - / - /MECL- 1 - / - /LMP7 - / - ），以确定免疫蛋白酶体缺乏的促凋亡效应是否需要BIM，并且该目标还将评估免疫蛋白酶体缺乏症对免疫疾病的影响对Pro-Apoptotic Bcl-2的功能和脱位的影响。 2。确定免疫蛋白酶体的结构和功能特征，这些特征对于它们的抗凋亡活性至关重要。该目标将涉及测试LMP7和相关蛋白酶体亚基调节活性T细胞凋亡的活性位点和组装突变体的能力，并确定正常活化T细胞中免疫蛋白酶体的表达是否与凋亡活性相关。从长期的，阐明免疫蛋白酶体在活化的T细胞凋亡中作用的分子机制将进一步进一步理解免疫记忆发展的发展，并可能识别出增强自身免疫性疾病病原体的自身反应T细胞凋亡的凋亡，可抑制T细胞的病原体，从而促进了TORISE或CONCONTIS tON tO造成TON的侵蚀性。必须控制对“威胁”（例如感染或肿瘤）的免疫反应，以提供记忆以保护将来免受类似威胁的方式（免疫），同时又可以防止对自己的自我造成不必要的损害（自身免疫性）。该项目的目的是提高我们对参与该控制系统的分子的理解，这可能会导致对该系统自我抑制或分解的疾病的更好治疗（感染，癌症或自身免疫性疾病）。