Regulation of T helper cell differentiation by integrated STAT and Ikaros zinc finger transcription factor mechanisms

项目摘要 为了协调病原体特异性免疫应答，CD 4 + T辅助细胞必须分化成不同的免疫应答。 效应子亚型，包括TH 1、TH 2、TH 17和T滤泡辅助（TFH）细胞。辅助性T细胞亚型 分化在基因表达水平上受到调节，并响应于细胞外源性细胞因子而发生 信号.该领域的流行模型是，独特的、谱系定义的转录因子是 在前体细胞中通过细胞因子信号传导被激活，并且主要负责建立细胞类型 促进T辅助细胞分化的特异性基因表达谱。例如，血统定义 转录因子Bcl-6被描述为TFH细胞发育的“主调节因子”。而 Bcl-6等因子的重要性是毋庸置疑的，单一因子决定T辅助细胞分化的概念 已经受到挑战的发现表明，每个辅助性T细胞亚群的分化需要 复杂的、由基因驱动的转录网络的协同作用，而不是个体的功能。 转录因子识别构成这些网络的蛋白质和分子生物学特征， 他们用来促进细胞特异性基因表达模式的机制将显著促进我们的研究。 了解辅助性T细胞分化的调控规律，为合理的 设计新型、日益有效的免疫疗法。 我们研究计划的长期目标是阐明调节T细胞的转录网络。 辅助细胞分化，并确定亚型特异性基因表达模式的机制， 监管.在本申请中，我们关注两个显著的转录因子家族的作用： 转录转导和激活因子（STAT）和Ikaros锌指（IkZF）因子。令人兴奋的初步 来自我们实验室的数据表明，IkZF因子Aiolos与STAT 3合作，诱导 Bcl-6从机制上讲，共享的细胞因子环境允许增加的Aiolos表达，STAT 3激活， 以及与Bcl 6启动子相关的Aiolos/STAT 3复合物的形成。总的来说，这些 研究结果提供了科学的前提下，在这项工作中的应用，并建议， STAT和IkZF转录因子家族的这些成员代表了一种新的调节机制 促进Bcl-6表达和TFH细胞发育。因为IkZF和STAT家族成员 是高度保守的，我们提出了概念上的创新假设，即不同的T细胞的分化 包括TFH细胞在内的辅助细胞亚群依赖于亚型特异性的 IkZF/STAT复合物。我们将通过以下方式检验这一假设：i）阐明协调机制， Aiolos和STAT 3激活Bcl-6表达，ii）定义Aiolos/STAT 3复合物在TFH分化中的作用， 和iii）确定保守的IkZF/STAT相互作用是否调节额外的T辅助细胞基因程序。

PROJECT SUMMARY In order to coordinate pathogen-specific immune responses, CD4+ T helper cells must differentiate into distinct effector subtypes, including TH1, TH2, TH17, and T follicular helper (TFH) cells. T helper cell subtype differentiation is regulated at the gene expression level and occurs in response to cell-extrinsic cytokine signals. The prevailing model in the field has been that unique, lineage-defining transcription factors are activated in precursor cells by cytokine signaling and are largely responsible for establishing the cell-type specific gene expression profiles that promote T helper cell differentiation. For example, the lineage-defining transcription factor Bcl-6 has been described as as the “master regulator” of TFH cell development. While the importance of factors like Bcl-6 is unquestioned, the notion of singular factors dictating T helper differentiation has been challenged by findings demonstrating that the differentiation of each T helper subset requires the concerted action of complex, cytokine-driven transcriptional networks, rather than the function of an individual transcription factor. The identification of the proteins that comprise these networks and the molecular mechanisms they utilize to promote cell-specific gene expression patterns will significantly advance our understanding of the regulation of T helper cell differentiation, and establish a scientific basis for the rational design of novel, increasingly effective immunotherapies. The long-term goal of our research program is to elucidate the transcriptional networks that regulate T helper cell differentiation and define the mechanisms by which subtype-specific gene expression patterns are regulated. In this application, we are focusing on the role of two notable transcription factor families: Signal Transducer and Activator of Transcription (STAT) and Ikaros Zinc Finger (IkZF) factors. Exciting preliminary data from our lab indicates that the IkZF factor Aiolos cooperates with STAT3 to induce the expression of Bcl-6. Mechanistically, a shared cytokine environment allows for increased Aiolos expression, STAT3 activation, and the formation of an Aiolos/STAT3 complex that associates with the Bcl6 promoter. Collectively, these findings provide the scientific premise for the work in this application and suggest that the interplay between these members of the STAT and IkZF transcription factor families represents a novel regulatory mechanism that promotes Bcl-6 expression and perhaps TFH cell development. Because IkZF and STAT family members are highly conserved, we propose the conceptually innovative hypothesis that the differentiation of distinct T helper subsets, including that of TFH cells, is dependent upon the formation and activity of subtype-specific IkZF/STAT complexes. We will test this hypothesis by i) elucidating the coordinated mechanisms by which Aiolos and STAT3 activate Bcl-6 expression, ii) defining the role of Aiolos/STAT3 complexes in TFH differentiation, and iii) determining whether conserved IkZF/STAT interactions regulate additional T helper cell gene programs.