Epigenetic control of the T-bet Transcriptome by Foxp3 in Tregs expressing T-bet

描述（由申请人提供）：CD 4辅助性T细胞分化由“主”转录因子控制，所述转录因子使细胞成为Th 1、Th 2或Thi 7细胞或Treg。以前认为这些转录因子的表达是相互排斥的。然而，最近，它已被证明，T辅助细胞可以表达多种“主”转录因子在体内。这些单独的转录因子如何诱导其特定的转录谱是很好理解的，但很少有人知道这些“主”转录因子如何在共表达它们的细胞中相互作用。基于我们关于表达Foxp 3和T-bet的细胞的初步数据，这些表达T-bet的TcB的转录组是独特的。虽然一些Th特异性基因被表达（例如，CXCR 3），其他Th相关基因的表达被抑制（例如，IFN γ）。尽管Foxp 3在选择性抑制T-bet转录组中的直接作用尚未显示，并且考虑到Foxp 3在抑制Tbet中的基因转录中的重要作用，推测Foxp 3在这些细胞中Thi基因的差异沉默中起关键作用是诱人的。本申请中提出的实验旨在确定Foxp 3在这种抑制中的作用以及FoxpS介导沉默的机制。将产生稳定且可诱导表达Foxp 3的细胞系，并用表达T-bet的质粒转染。使用高密度微阵列，分析这些细胞的转录谱以鉴定一组在Foxp 3表达细胞中下调的Th特异性基因。然后，我们将检查Foxp 3在这些启动子处诱导的表观遗传修饰，将这些变化与不受Foxp 3表达影响的Th特异性基因进行比较。通过本提案中产生的工具，我们将获得前所未有的理解，不仅是FoxpS在沉默基因转录中所利用的调控机制，而且是组蛋白修饰在驱动T细胞发育和分化中的重要性。此外，对FoxpS如何沉默促炎基因（如IFN γ）的详细了解可能有助于开发治疗方法，以限制自身免疫性疾病（如1型糖尿病，类风湿性关节炎和多发性硬化症）中的炎症，或通过抑制慢性感染，疫苗接种和癌症中的Treg控制来增强免疫反应。了解促炎蛋白质的表达是如何被抑制的可能允许开发新的抗炎疗法。由于许多自身免疫性疾病是由过度炎症引起的，这涉及许多疾病，包括I型糖尿病，类风湿性关节炎和多发性硬化症。或者，预防这种抑制的治疗可以用于增强慢性病毒感染、疫苗接种或癌症中的免疫应答。

DESCRIPTION (provided by applicant): CD4 T helper cell differentiation is controlled by 'master' transcription factors that commit the cell to become a Th1, Th2 or Thi 7 cell or a Treg. It was previously believed that the expression of these transcription factors was mutually exclusive. However, recently, it has been demonstrated that T helper cells can express multiple 'master' transcription factors in vivo. How these individual transcription factors induce their specific transcription profile is well understood, yet little is known about how these 'master' transcription factors interact in cells co-expressing them. Based on our preliminary data on cells expressing both Foxp3 and T- bet, the transcriptome of these T-bet-expressing Tregs is unique. While some Thi-specific genes are expressed (e.g., CXCR3), the expression of other Thi-associated genes is suppressed (e.g., IFNy). Despite the fact that a direct role of Foxp3 in the selective suppression of the T-bet transcriptome has not been shown, and, given the important role of Foxp3 in suppressing gene transcription in Tregs, it is tempting to speculate that Foxp3 plays a critical role in the differential silencing of Thi genes in these cells. The experiments proposed in this application aim to determine the role of Foxp3 in this repression and the mechanism by which FoxpS mediates the silencing. Cell lines that stably and inducibly express Foxp3, will be generated and transfected with T-bet-expressing plasmids. Using high density microarrays, the transcriptional profile of these cells will be analyzed to identify a panel of Thi-specific genes downregulated in Foxp3-expressing cells. We will then examine the epigenetic modifications induced by Foxp3 at these promoters, comparing these changes to Thi-specific genes that are not affected by Foxp3 expression. With the tools generated in this proposal we will gain an unprecedented understanding of not only the regulatory mechanism utilized by FoxpS in silencing gene transcription, but also the importance of histone modifications in driving T cell development and differentiation. Furthermore, a detailed understanding of how FoxpS functions to silence pro-inflammatory genes, like IFNy, may allow for the development of therapies to limit inflammation in autoimmune diseases such as type 1 diabetes, rheumatoid arthritis and multiple sclerosis, or boost the immune response by dampening Treg control in chronic infections, vaccination and cancer PUBLIC HEALTH RELEVANCE: understanding how the expression of pro-inflammatory proteins is inhibited may allow for the development of novel anti-inflammatory therapies. As, many autoimmune disease are caused by excessive inflammation, this has implicated for a number of conditions including type I diabetes, rheumatoid arthritis and multiple sclerosis. Alternatively, treatments preventing this inhibition may be used to boost the immune response in chronic viral infections, vaccination or cancer.