Induction of NFATc1 Controls the Fate of Activated T Cells

活化T细胞核因子(NFAT)家族的转录因子控制淋巴细胞的激活和效应功能。环孢素A或FK506等免疫抑制剂对NFAT的抑制主要损害活化的T细胞的炎症功能，它们在移植医学上的巨大成功引发了医学革命。NFAT蛋白被胞浆中的钙/钙调神经磷酸酶信号级联激活。除了它们的翻译后调控外，最重要的NFAT家族成员之一NFATc1也在转录水平上受到调控。通过抗原受体刺激激活淋巴细胞，可诱导NFATc1/Aa短亚型的表达，该亚型在结构和功能上不同于所有其他NFAT蛋白，其结构和功能与所有其他NFAT蛋白不同。我们先前的研究表明，NFATc1/Aa的诱导受位于NFATc1基因最后一个内含子的远程转录增强子das E2的控制。为了确定这个调控元件的生理作用，我们建立了一个新的转基因小鼠系，在其中可以选择性地删除T细胞中的E2增强子。E2的缺失削弱了NFATc1/AA的诱导，导致活化T细胞中大量NFATc1靶基因的强烈减少。在体内，E2的缺失不仅破坏了生发中心的形成和体液免疫，而且扰乱了对病毒感染的细胞免疫反应。病毒特异性T细胞的过继转移实验表明，NFATc1/AA的诱导防止了CD8+T细胞的(功能性)耗尽，并促进了它们在慢性感染受体小鼠中的存活。在这个项目中，我们将利用病毒感染和抗肿瘤免疫的模型来阐明NFATc1/AA诱导对记忆形成的影响，特别是对T细胞耗竭的影响。在表型和功能分析的同时，我们还将利用最先进的技术，如转录组学和代谢组学，在生理、细胞和分子水平上确定E2对T细胞分化和功能的影响。我们的实验将提供一个全面的观点，即在持续感染和癌变过程中，E2和NFATc1/AA的诱导如何控制T细胞介导的免疫反应。该项目的结果不仅解决了适应性免疫反应的基本分子问题，还将为开发先进的T细胞介导的抗癌免疫疗法铺平道路。

Transcription factors of the ‚Nuclear Factor of Activated T Cell‘ (NFAT) family control the activation and effector function of lymphocytes. Inhibition of NFAT by immunosuppresants, such as cyclosporin A or FK506, impairs primarily the inflammatory function of activated T cells, and their overwhelming success in transplantation medicine led to a revolution in medicine. NFAT proteins are activated by a Ca++/calcineurin signaling cascade in the cytosol. In addition to their posttranslational regulation, one of the most prominent NFAT family members, NFATc1, is also regulated at the transcriptional level. Activation of lymphocytes by antigen receptor stimulation induces the expression of a short isoform, NFATc1/aA, which differs structurally and functionally from all other NFAT proteins by individual terminal peptides and its anti-apoptotic properties.We showed previously that the NFATc1/aA induction is controlled by a remote transcriptional enhancer, designated das E2, located within the last intron of the Nfatc1 gene. To determine the physiological role of this regulatory element, we generated a novel transgenic mouse line in which the E2 enhancer can selectively be deleted in T cells. Loss of the E2 impaired the induction of NFATc1/aA resulting in a strong decrease of numerous NFATc1 target genes in activated T cells. In vivo, deletion of E2 not only abrogated germinal center formation and humoral immunity but also perturbed the cellular immune responses to viral infection. Adoptive transfer experiments with virus-specific T cells revealed that the induction of NFATc1/aA prevents the (functional) exhaustion of CD8+ T cells and promotes their survival in chronically infected recipient mice. This specific function of E2 is not only important during viral infection but has also important (clinical) implications for anti-tumor immunity.In this project, we will elucidate the effect of NFATc1/aA induction on memory formation and, in particular, on T cell exhaustion using models of viral infection and anti-tumor immunity. In parallel to phenotypic and functional analyses, we will also employ state-of-the-art technologies, such as transcriptomics and metabolomics, to define the impact of E2 on T cell differentiation and function at the physiological, cellular and molecular level.Our experiments will provide a comprehensive view how E2 and the induction of NFATc1/aA induction controls T cell-mediated immune responses during persistent infections and cancerogenesis. The results of this project are not only addressing fundamental molecular questions of adaptive immune responses but will also pave the way to develop advanced T cell-mediated immunotherapies against cancer.