Epigenetic Regulation by WASP of Human TBX21 Gene Transcription Program

描述（由申请人提供）：拟议研究的总体目标是在染色质调控水平上定义Wiskott-Aldrich综合征蛋白（WASp）在编程CD4 T细胞（Th）1分化和1型病原体特异性免疫发展的分子和转录途径中的新核作用。TBX21基因编码T-BET蛋白，这是th1的主调控因子，它与RUNX3一起驱动靶细胞因子基因IFNG的激活。这些激活事件对于确定Th1细胞的命运非常重要。Wiskott-Aldrich综合征（WAS）患儿的T细胞缺乏WASp的表达，同时表现出T- bet的缺乏，不能产生th1细胞因子IFN，并发生细胞内病原体的严重全身性感染，表明集体未能产生保护性th1免疫反应。相反，有迹象表明，部分WAS患者和一些WAS小鼠模型中的th2反应在病理上被夸大了。因此，在一些小鼠WAS模型中，自身免疫性结肠炎的发生是由th2细胞因子驱动的。总的来说，这些观察结果表明，Th1与Th2免疫的不平衡激活可能是WAS及其并发症的病理生理基础。因此，这项应用的具体目的是了解WASp在染色质水平上调控Th1网络基因的作用，并阐明人类WAS中Th1特异性免疫缺陷的分子基础。使用不同生化方法的组合，我们将描述Th1细胞基因组（Aim1）中WASp的蛋白质：蛋白质相互作用，测试WASp在有利于高产转录的局部表观遗传修饰中的作用，然后确定这些调节事件中的扰动可能是由于WASp的缺失（Aim 2）或突变WASp的存在（Aim 3）。这些研究有望阐明WASp在人类靶免疫功能基因的表观遗传和转录控制中的新功能，并为人类WAS的系统性免疫缺陷及其相关并发症揭示全新的分子基础。

DESCRIPTION (provided by applicant): The overall objective of the proposed research is to define, at the level of chromatin regulation, a novel nuclear role of Wiskott-Aldrich syndrome protein (WASp) in the molecular and transcriptional pathways that program CD4 T cell (Th)1 differentiation and the development of type 1-pathogen-specific immunity. TBX21 gene encodes T-BET protein, the Th1-master regulator, which in concert with RUNX3 drives the activation of the target cytokine gene, IFNG. These activation events are important for specifying the Th1 cell fate. T cells from children with Wiskott-Aldrich syndrome (WAS), which lack expression of WASp, exhibit a concomitant deficiency of T-BET, fail to produce Th1-cytokine IFN, and develop severe systemic infections from intracellular pathogens, indicating a collective failure to develop a protective Th1-immune response. In contrast, there are indications that the Th2-response in a subset of WAS patients and in some murine models of WAS is pathologically exaggerated. Accordingly, the development of autoimmune colitis in some murine WAS model is Th2-cytokine-driven. Collectively, these observations suggests that an unbalanced activation of Th1 versus Th2 immunity may underlie the pathophysiology of WAS and its attendant complications. The specific objective for this application, therefore, is to understand WASp's role in the regulation of the Th1 network genes at a chromatin level, and clarify the molecular underpinnings of Th1-specific immune deficiency in human WAS. Using a combination of different biochemical approaches, we will delineate the protein:protein interactions of WASp in the Th1 cell genome (Aim1), test the role of WASp in local epigenetic modifications that favor productive transcription, and then identify perturbations in these regulatory events that may result from the absence of WASp (Aim 2) or from the presence of mutated WASp (Aim 3). These studies are expected to elucidate a previously unexplored, novel function of WASp in the epigenetic and transcriptional control of its target immune function genes in humans, and unearth an entirely new molecular basis for systemic immunodeficiency and the associated complications in the human WAS.