GABP-controlled gene regulatory network in T lymphocytes

描述（由申请方提供）：针对外源抗原的保护性细胞免疫应答依赖于功能性T淋巴细胞。T细胞的发育、活化和分化受不同组合的转录因子控制。GA结合蛋白（GABP）是一种广泛表达的Ets家族转录因子，其功能由两个不同的亚基GABP 1和GABP 2组成，分别介导DNA结合和转录激活。以前，我们已经证明，GABP关键调节T细胞中白细胞介素-7受体1（IL-7 R1）链的表达，表明GABP在免疫系统中的关键作用。鉴于GABP 1基因的完全失活导致植入前致死，我们已经产生了GABP 1突变小鼠品系，其是亚型的并且在胚胎发生期间具有延长的存活。在我们使用来自GABP 1突变胚胎的胎肝细胞重建Rag 2缺陷小鼠的淋巴区室的初步研究中，我们发现GABP在胸腺细胞发育和T细胞介导的免疫应答中具有重要作用。 本研究旨在构建T细胞中GABP调控下的层次性、交互性基因调控网络。我们的长期目标是阐明GABP如何通过调控其靶基因以及与其他关键因子的相互作用来调控T淋巴细胞生成和T细胞免疫应答。这些信息将为调节生理和病理条件下造血干细胞分化和免疫反应的结果提供科学依据。 具体目标。确定T淋巴细胞中GABP的直接靶基因，建立GABP调控的T细胞生物学基因调控网络。利用我们的基因芯片分析数据，我们将扩大我们的研究，以确定GABP直接靶基因的方法，比较基因组学和染色质免疫沉淀分析（ChIP）与小鼠启动子阵列（ChIP-on-chip）。然后，我们将绘制GABP结合元件的精确位置，并研究它们在激活/抑制相应基因中的功能重要性。有了这些知识，T细胞中的基因调控网络可以构建，这将提供一个平台，更广泛的研究胸腺细胞发育和T细胞功能的相互作用的转录控制。在具有遗传性和获得性免疫缺陷的个体中，免疫系统的重建仍然是一个主要挑战，并且更好地理解造血干细胞分化为淋巴谱系的分子机制对于改善免疫系统重建策略是至关重要的。该项目将深入了解GABP，一种转录因子，如何有助于将造血干细胞指定为T细胞系细胞，以及GABP如何调节细胞免疫反应。这些知识将为在生理和病理条件下操纵造血干细胞分化和免疫应答的结果提供科学依据。

DESCRIPTION (provided by applicant): Protective cellular immune responses against foreign antigens rely on functional T lymphocytes. The development, activation and differentiation of T cells are controlled by transcription factors in different combinations. GA binding protein (GABP) is a ubiquitously expressed Ets family transcription factor, and functional GABP consists of two different subunits, GABP1 and GABP2, which mediate DNA binding and transactivation, respectively. Previously we have demonstrated that GABP critically regulates the expression of interleukin-7 receptor 1 (IL-7R1) chain in T cells, suggesting a key role of GABP in the immune system. Whereas complete inactivation of the GABP1 gene caused pre- implantation lethality, we have generated a GABP1 mutant mouse strain that is hypomorphic and has prolonged survival during embryogenesis. In our preliminary studies using fetal liver cells from the GABP1 mutant embryos to reconstitute lymphoid compartment in Rag2-deficient mice, we found that GABP has essential roles in thymocyte development and T cell-mediated immune responses. This research project aims to construct a hierarchical and interactive gene regulatory network under the control of GABP in T cells. Our long-term goal is to elucidate how GABP programs T lymphopoiesis and T cell immune responses through regulating its target genes and interacting with other key factors. This information will provide a scientific basis for modulating outcomes of hematopoietic stem cell differentiation and immune responses under physiological and pathological conditions. Specific Aim. To identify direct GABP target genes in T lymphocytes and to establish a GABP- controlled gene regulatory network programming T cell biology. Taking advantage of our GeneChip microarray analysis data, we will extend our studies to identify GABP direct target genes using approaches of comparative genomics and chromatin immunoprecipitation assay (ChIP) coupled with a mouse promoter array (ChIP-on-chip). We will then map the precise locations of GABP-binding elements and investigate their functional importance in activating/repressing respective genes. With this knowledge, a gene regulatory network in T cells can be constructed, and this will provide a platform for a broader investigation of the interactive transcriptional control of thymocyte development and T cell functions. Reconstitution of the immune system in individuals with inherited and acquired immunodeficiency remains a major challenge, and a better understanding of the molecular mechanism by which hematopoietic stem cells differentiate to lymphoid lineages is fundamental to improve strategies for immune system reconstitution. This project will generate insights into how GABP, a transcription factor, contributes to specifying hematopoietic stem cells to the T-lineage cells, and how GABP modulates the cellular immune response. This knowledge will provide a scientific basis for manipulating outcomes of hematopoietic stem cell differentiation and immune response under physiological and pathological conditions.