EGR2 in T cell tolerance

描述（由申请人提供）：外周免疫耐受的一个关键机制是通过T细胞能量的过程发生的，特别是在肿瘤环境中。我们之前已经表明，二酰基甘油激酶（DGK）家族脂质激酶的上调表达参与抑制rasgrp介导的Ras激活，并有助于在无能状态下T细胞功能障碍。其他研究也暗示了额外的负调节信号蛋白的上调，这可能有助于维持T细胞功能障碍。最近，通过条件敲除研究、基因表达谱分析和ChIP-Seq实验，我们已经确定转录因子EGR2是T细胞能量中这些负调节因子表达的中心调节因子。重要的是，新的egr2驱动的靶标已经出现，这些靶标是细胞表面标记物，可能允许流式细胞术鉴定无能细胞。该提案的主要目标是确定EGR2对外周肿瘤耐受的贡献。在特异性目标1中，我们将确定体外外周血T细胞条件删除EGR2的影响。将评估T细胞能量的诱导、抗肿瘤免疫的产生和自身免疫进化的潜力。在特异性目标2中，将研究EGR2调控基因子集在T细胞生物学中的相关性。我们将重点讨论分泌因子CCL1；CRTAM/LAG3/4-1BB的表面表达；以及信号蛋白7A的功能作用。这些标记物的组合是否能识别肿瘤微环境中的无能细胞还有待确定。在Specific Aim 3中，将评估浸润人类黑色素瘤的T细胞中EGR2及其靶点的表达，以走向临床意义。总之，这些研究将大大拓宽和加深我们对体内EGR2和T细胞能量的理解，并有望发现可用于癌症免疫治疗的临床应用策略。

DESCRIPTION (provided by applicant): One critical mechanism of peripheral immunologic tolerance occurs through the process of T cell anergy, particularly in the tumor context. We previously have shown that upregulated expression of lipid kinases of the diacylglycerol kinase (DGK) family participate in the suppression of RasGRP-mediated Ras activation and contribute to T cell dysfunction in the anergic state. Other studies have implicated upregulation of additional negative regulatory signaling proteins, which may cooperate to maintain T cell dysfunction. Recently, through conditional knockout studies, gene expression profiling and ChIP-Seq experiments, we have identified the transcription factor EGR2 as a central regulator of expression of these negative regulatory factors in T cell anergy. Importantly, new EGR2-driven targets have emerged that are cell surface markers, which may allow flow cytometric identification of anergic cells. The major goal of this proposal is to determine the contribution o EGR2 towards peripheral tolerance to tumors. In Specific Aim 1 we will determine the effects of conditional deletion of EGR2 in peripheral T cells in vivo. Induction of T cell anergy, generation of anti-tumor immunity, and potential for evolving autoimmunity will be assessed. In Specific Aim 2, the relevance of a subset of EGR2- regulated genes in T cell biology will be investigated. We will focus on the secreted factor CCL1; the surface expression of CRTAM/LAG3/4-1BB; and the functional role of Semaphorin 7A. Whether combinations of these markers can identify anergic cells in the tumor microenvironment will be determined. In Specific Aim 3, expression of EGR2 and its targets in T cells infiltrating human melanoma will be evaluated, to move towards clinical relevance. Together, these studies will substantially broaden and deepen our understanding of EGR2 and T cell anergy in vivo, and are expected to uncover strategies that can have clinical application towards immunotherapy of cancer.