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细胞无反应性过程发生的，特别是在肿瘤背景下。我们以前已经表明，上调表达的二酰基甘油激酶（DGK）家族的脂质激酶参与抑制RasGRP介导的Ras激活，并有助于T细胞功能障碍的无反应性状态。其他研究已经暗示了额外的负调节信号蛋白的上调，其可以协作以维持T细胞功能障碍。最近，通过条件敲除研究，基因表达谱和ChIP-Seq实验，我们已经确定了转录因子EGR 2作为这些负调控因子在T细胞无能中表达的中心调节因子。重要的是，已经出现了新的EGR 2驱动的靶点，它们是细胞表面标志物，可以允许流式细胞术鉴定无反应性细胞。该提议的主要目标是确定EGFR 2对肿瘤外周耐受的贡献。在具体目标1中，我们将确定在体内外周T细胞中EGFR 2的条件性缺失的影响。将评估T细胞无反应性的诱导、抗肿瘤免疫的产生和发展自身免疫的潜力。在特定目标2中，将研究T细胞生物学中EGFR 2调节基因子集的相关性。我们将重点关注分泌因子CCL 1; CRTAM/LAG 3/4-1BB的表面表达;以及Semaphorin 7A的功能作用。这些标志物的组合是否可以识别肿瘤微环境中的无反应性细胞将被确定。在特定目标3中，将评价浸润人黑素瘤的T细胞中EGFR 2及其靶标的表达，以走向临床相关性。总之，这些研究将大大拓宽和加深我们对体内EGR 2和T细胞无反应性的理解，并有望揭示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.