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节水平上确定Wiskott-Aldrich综合征蛋白(WASP)在分子和转录途径中的新的核作用，该途径编程CD4T细胞(Th)1的分化和1型病原体特异性免疫的发展。Tbx21基因编码T-BET蛋白，T-BET蛋白是Th1的主控调节蛋白，与RUNX3协同驱动靶细胞因子基因IFNG的激活。这些激活事件对于确定Th1细胞的命运很重要。Wiskott-Aldrich综合征(Wiskott-Aldrich)患儿的T细胞缺乏黄蜂蛋白的表达，表现出T-BET的伴随缺陷，不能产生Th1细胞因子干扰素，并因细胞内病原体而发生严重的全身感染，表明集体未能形成保护性的Th1免疫反应。相反，有迹象表明，在一组风湿病患者和一些风湿病小鼠模型中，Th2反应在病理上被夸大了。因此，一些小鼠自身免疫性结肠炎的发展是由Th2细胞因子驱动的。总之，这些观察表明Th1和Th2免疫的不平衡激活可能是WAS及其伴随的并发症的病理生理学基础。因此，这一应用的特定目标是在染色质水平上了解黄蜂在Th1网络基因调控中的作用，并阐明人类Th1特异性免疫缺陷的分子基础。使用不同的生化方法的组合，我们将描绘蛋白质：黄蜂在Th1细胞基因组中的蛋白质相互作用(Aim1)，测试黄蜂在有利于生产性转录的局部表观遗传修饰中的作用，然后确定这些调控事件中可能由于没有黄蜂(目标2)或存在突变的黄蜂(目标3)而导致的扰动。这些研究有望阐明黄蜂在其目标免疫功能基因的表观遗传和转录控制中的一种以前未被探索的新功能，并揭示全身性免疫缺陷及其相关并发症的全新分子基础。

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.