Mechanisms controlling Foxp3 expression and regulatory T cell homeostasis

控制 Foxp3 表达和调节性 T 细胞稳态的机制

• 批准号: 8658598
• 负责人: Ye Zheng
• 金额: $ 45.59万
• 依托单位: SALK INSTITUTE FOR BIOLOGICAL STUDIES
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-06-01 至 2014-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8658598
• 关键词: Adopted; Antigens; Attenuated; Autoimmune Diseases; Autoimmune Process; Autoimmunity; Biological Assay; Biology; Candidate Disease Gene; Cells; Code; Control Locus; Defect; Dendritic Cells; Development; Equilibrium; Functional RNA; Generations; Genomics; Goals; Homeostasis; Human; Immune; Immune response; Immune system; Individual; Insulin-Dependent Diabetes Mellitus; Knock-out; Knockout Mice; Lead; Lymphocyte Function; Lymphocytic choriomeningitis virus; Maintenance; Malignant Neoplasms; Molecular; Mus; Names; Outcome; Pathway interactions; Peripheral; Phenotype; Play; Population; Population Dynamics; Protein Binding; Regulatory T-Lymphocyte; Role; Sequence Analysis; Shapes; Signal Pathway; System; T-Lymphocyte; Techniques; Testing; Therapeutic; Thymectomy; Transforming Growth Factor beta; Transgenic Mice; base; chimeric antibody; chromatin immunoprecipitation; follow-up; immunogenic; immunopathology; in vivo; insight; mouse model; pathogen; prevent; small hairpin RNA; transcription factor

DESCRIPTION (provided by applicant): A functional immune system has to maintain a delicate balance between effective elimination of foreign pathogens and minimizing collateral damage to the host. Regulatory T cells (Tregs), a subset of T lymphocytes, function as suppressor of the immune system and play a critical role in maintaining immune homeostasis. Defects in Treg function lead to autoimmune diseases and immunopathology in humans and mice. One of the milestones in Treg biology field was the identification of transcription factor Foxp3 as an essential regulator of Treg development and function. The goal of this project is to elucidate the molecular mechanisms that control Foxp3 expression, which will determine how regulatory T cells are generated and maintained. By comparing Foxp3 genomic sequences of different species, Dr. Zheng and colleagues identified three intronic regions that are evolutionarily conserved, which they named CNS1, 2, and 3 (Conserved Non- coding Sequence). They hypothesized that these CNS regions could play an important role in regulating Foxp3 expression, and proceeded to knockout individual Foxp3 CNS regions in mice. Each of the three CNS knockout mice showed different defects in their Treg population, suggesting they play different roles in control of Foxp3 expression. CNS3 is required for thymic development of Tregs, whereas CNS1 is involved in TGF-beta dependent peripheral conversion of Tregs. Most interestingly, CNS2 plays a role in maintaining Foxp3 expression and stabilizing Treg lineage. In the current proposal, Dr. Zheng's group will follow up on the initial characterization of the Foxp3 CNS knockout mice to perform a detailed study on how the CNS regions control regulatory T cell homeostasis at both cellular and molecular levels. First, they will use more physiologically relevant mouse models to investigate the role of Foxp3 CNS2 in maintenance of natural Treg lineage stability and perform TCR repertoire study to examine the flux of Treg subsets in the absence of CNS2 (Aim 1). Second, they will explore the role of Foxp3 CNS regions in generation and maintenance of antigen-specific Tregs induced in vivo by anti-DEC205 chimeric antibody (Aim 2). Lastly, they plan to use a modified chromatin immunoprecipitation assay to identify proteins bound to CNS regions that regulate Foxp3 expression (Aim 3). The study proposed here will provide more insight on mechanisms controlling Treg homeostasis, and potentially generate new avenues to manipulate Tregs to attenuate or augment the amplitude of immune response for treatment of autoimmune diseases and cancer.

描述（由申请人提供）：功能免疫系统必须在有效消除外来病原体与最小化宿主的附带损害之间保持微妙的平衡。调节性T细胞（Tregs）（Tregs）是T淋巴细胞的一部分，起到免疫系统的抑制作用，在维持免疫稳态中起着关键作用。 Treg功能的缺陷导致人类和小鼠的自身免疫性疾病和免疫病理学。 Treg生物学领域的里程碑之一是将转录因子FOXP3鉴定为Treg开发和功能的基本调节剂。该项目的目的是阐明控制FOXP3表达的分子机制，这将确定调节性T细胞的产生和维持方式。通过比较不同物种的Foxp3基因组序列，Zheng博士及其同事确定了三个具有进化保守的内含子区域，它们将其命名为CNS1、2和3（保守的非编码序列）。他们假设这些中枢神经系统地区可能在调节Foxp3表达中发挥重要作用，并继续淘汰小鼠中的单个FOXP3 CNS区域。三只CNS敲除小鼠中的每一个在Treg人群中显示出不同的缺陷，这表明它们在控制Foxp3表达中起着不同的作用。 CNS3是Tregs的胸腺发育所必需的，而CNS1参与TGF-β依赖性的Tregs的外围转化。最有趣的是，CNS2在维持FOXP3表达和稳定Treg谱系方面起着作用。在当前的建议中，郑博士的小组将跟进Foxp3 CNS敲除小鼠的初始表征，以详细研究中枢神经系统区域如何控制细胞和分子水平的调节性T细胞稳态。首先，他们将使用更多与生理相关的小鼠模型来研究FOXP3 CNS2在维持天然Treg谱系稳定性中的作用，并进行TCR库库研究，以检查在没有CNS2的情况下Treg子集的通量（AIM 1）。其次，他们将探讨FOXP3 CNS区域在抗DEC205嵌合抗体在体内诱导的抗原特异性Treg的生成和维持中的作用（AIM 2）。最后，他们计划使用改良的染色质免疫沉淀测定法确定与调节FOXP3表达的CNS区域结合的蛋白质（AIM 3）。此处提出的研究将为控制Treg稳态的机制提供更多的见解，并可能产生新的途径来操纵Treg，以减轻或增加免疫反应的幅度，以治疗自身免疫性疾病和癌症。