How beta-catenin expands Foxp3+RORgammat+ Pro-inflammatory T-regulatory cells

摘要 调节性T细胞（Treg）的可塑性和功能多样性对于维持健康至关重要。 免疫力，但它也在疾病中被利用。我们已经描述了表达高水平β- catenin和促进炎症。炎症性肠病患者中这些THBE的频率增加 (and小鼠结肠炎）、结肠癌（和小鼠息肉病）以及多发性硬化症（和小鼠EAE）。 显性活性β-catenin的表达，或Tcf-1的去除，都能促进Rorγ在Tcf-1中的表达。 Th 17谱系的典型转录因子，并促进Th 17分化标记。在 在健康小鼠的肠系膜淋巴结（MLN）中，我们鉴定出至少5种转录上不同的激活的 集群的Tibet。其中一个簇由Rorγt的表达定义，并具有显著的Th 17 分化特征在Tcf-1缺陷型Tcells中，Th 17分化特征扩展到所有其他细胞， RORγt簇出现频率增加。尽管Tcf-1缺陷型Tcf-1更Th 17， 比如抑制T细胞，但它们无法抑制炎症。这表明Treg的分叉 抑制功能，并回避了一个问题，即它是否涉及TCF-1和Foxp 3之间的合作。 我们已经发现，TCF-1和Foxp 3共结合参与T细胞活化的基因的增强子元件， Th 17分化。β-连环蛋白在这些增强子处诱导新的可接近的染色质区域， 上调相关基因的表达。此外，E-box结合蛋白HEB 与TCF-1和潜在的Foxp 3一起调节这些基因，因为TCF-1和Foxp 3两者的Treg特异性消融 HEB（但不是每一种单独）拯救与β-连环蛋白相关的炎症和自身免疫性病理 在Tibet中激活。因此，HEB调节RORγt，抑制Foxp 3和外周Treg的发育。我们 研究结果与FoxP 3直接激活或抑制转录的观点一致， 依赖伙伴的方式。他们进一步暗示β-连环蛋白、TCF-1和HEB与Foxp 3合作， 独立调节多种Treg抑制活性。基于这些发现，我们假设， Wnt/β-catenin信号通过控制调节Treg抑制功能和多样性， 接近Foxp 3和HEB以选择与Tcf-1结合的染色质位点。为了具体说明这一假设， 目的1我们将确定β-连环蛋白和Tcf-1在制备Foxp 3结合的表观遗传景观中的作用 以及调节性T细胞类型多样性的形成。在具体的目标2中，我们将确定分泌的Wnt配体在细胞中的作用。 定义结肠浸润性THP的功能特性。拟议的研究将阐明基本的共同点， 调节健康中Treg特性的TF之间的操作/拮抗作用，以及微环境如何 像Wnt这样的队列在疾病环境中利用它们。预期的发现有可能为新的 用于自身免疫和癌症的诊断和治疗工具。

ABSTRACT The plasticity and functional diversity of regulatory T cells (Tregs) is essential for the maintenance of healthy immunity but it is also exploited in disease. We have described a subset of Tregs that express high levels of β- catenin and promote inflammation. The frequency of these Tregs is increased in inflammatory bowel diseases (and mouse colitis), colon cancer (and mouse polyposis), as well as in multiple sclerosis (and mouse EAE). Expression of a dominant active β-catenin, or ablation of Tcf-1 in Tregs both foster expression of Rorγt the canonical transcription factor of the Th17 lineage, and promote a Th17 differentiation signature. In the mesenteric lymph nodes (MLN) of healthy mice, we identified at least 5 transcriptionally distinct activated clusters of Tregs. One of these clusters is defined by expression of Rorγt and has prominent Th17 differentiation characteristics. In Tcf-1 deficient Tregs the Th17 differentiation profile expanded to all other clusters, and the RORγt cluster increased in frequency. The Tcf-1 deficient Tregs in spite of being more Th17 like, suppressed T-cells, however they failed to suppress inflammation. This indicates a bifurcation of Treg suppressive functions and begs the question, of whether it involves a co-operation between TCF-1 and Foxp3. We have found that, TCF-1 and Foxp3 co-bind enhancer elements of genes involved in T cell activation and Th17 differentiation. β-catenin induces newly accessible chromatin regions at these enhancers and upregulates the expression of the associated genes. Moreover, the E-box binding protein HEB works together with TCF-1 and potentially also Foxp3 to regulate these genes, since Treg specific ablation of both TCF-1 and HEB (but not each one alone) rescues inflammatory and autoimmune pathologies associated with β-catenin activation in Tregs. Consistently, HEB regulates RORγt, represses Foxp3 and peripheral Treg development. Our findings are in line with the notion that FoxP3 directly activates or represses transcription, in a context- and partner-dependent manner. They further implicate β-catenin, TCF-1, and HEB in partnering with Foxp3 to independently regulate the diverse Treg suppressive activities. Based on these findings we hypothesize that, Wnt/β-catenin signaling differentially regulates Treg suppressive functions and diversity, by controlling access of Foxp3 and HEB to select chromatin sites bound by Tcf-1. To address this hypothesis in specific Aim 1 we will determine the role of β-catenin and Tcf-1 in preparing the epigenetic landscape for Foxp3 binding and in shaping Treg cell type diversity. In specific Aim 2 we will determine the role secreted Wnt ligands in defining the functional properties of colon infiltrating Tregs. The proposed studies will elucidate fundamental co- operations/antagonisms between TFs that regulate Treg properties in health, and how microenvironment queues like Wnts exploit them in disease settings. The expected findings have the potential to inform novel diagnostic and therapeutic tools for autoimmunity and cancer.