Regulation of PD-1 gene expression

描述（由申请方提供）：程序性细胞死亡-1（PD-1）是一种免疫抑制受体，在免疫激活后在CD 4和CD 8 T细胞表面瞬时表达，并在长期暴露于抗原的T细胞上高度表达。通过PD-1的信号传导可导致T细胞耗竭，这是抗原特异性T细胞不再对抗原特异性刺激作出反应的状态。如在许多持续性病毒感染中所观察到的，包括来自HIV、人丙型肝炎病毒和鼠淋巴细胞性脉络丛脑膜炎病毒（LCMV）的病毒感染，PD-1及其配体（PD-L1/L2）之间的抗体阻断导致“耗尽的”抗原特异性T细胞的功能再活化。结合PD 1阻断疗法的临床试验已经取得了令人印象深刻的成功;突出了该基因表达和调控的重要性。我们的工作表明，PD-1在转录水平上以复杂的方式受到调控，涉及9个顺式调控元件;一个阳性（NFATc 1和STAT 3）和阴性（Blimp-1和LSD 1）转录因子网络;以及一个动态的表观遗传调控程序，包括DNA甲基化。尽管有这些知识，顺式元件、反式因子和表观遗传途径如何整合以提供细胞类型和免疫应答调节的机制细节还没有很好地理解。这种理解是重要的，因为PD-1的表达和活性对于感染和癌症的保护性免疫反应的发展至关重要。为了阐明控制PD-1表达的分子机制，我们提出了三个目标，设计为1）定义感染后抗原特异性细胞中PD-1基因座的顺式调节图谱和相互作用; 2）理解在急性和病毒感染条件下NFATc 1、Blimp-1和STAT之间在调节PD-1中的相互作用;以及3）了解表观遗传沉默子LSD 1如何控制PD-1表达和该位点的DNA甲基化。为了研究这些目标，我们建立了一系列小鼠品系，这些小鼠品系将有条件地删除转录因子CR-C顺式元件 Blimp-1或表观遗传沉默子LSD 1在活化的CD 8 T细胞中的作用。我们已经建立了分析CD 8 T细胞的体外方法，并将使用LCMV结合急性和慢性病毒感染的体内系统，以探索这些因子控制PD-1的机制。最终，我们的研究将阐明控制PD-1表达的分子遗传学和表观遗传学程序，并将提供新的工具来操纵PD-1基因表达，这可能有助于治疗感染和癌症。

DESCRIPTION (provided by applicant): Programmed cell death-1 (PD-1) is an immune inhibitory receptor that is expressed transiently on the surface of CD4 and CD8 T cells following immune activation and is highly expressed on T cells chronically exposed to antigen. Signaling through PD-1 can result in T cell exhaustion, a state in which antigen-specific T cells no longer respond to antigen-specific stimulation. As observed in numerous persistent viral infections, including those from HIV, human hepatitis C virus, and murine lymphocytic choriomeningitis virus (LCMV), antibody blockade between PD-1 and its ligands (PD-L1/L2) results in the functional reactivation of "exhausted" antigen-specific T cells. Clinical trials incorporating a PD1 blockade therapy have demonstrated impressive success; highlighting the importance of the expression and regulation of this gene. Our work has shown that PD-1 is regulated at the level of transcription in a complex manner involving nine cis-regulatory elements; a network of positive (NFATc1 and STAT3) and negative (Blimp-1 and LSD1) transcription factors; and a dynamic epigenetic regulatory program, including DNA methylation. Despite this knowledge, the mechanistic details of how the cis-elements, trans-factors, and epigenetic pathways integrate to provide cell type and immune response regulation is not well understood. This understanding is important as PD-1's expression and activity is critical to the development of protective immune responses to infection and cancer. To elucidate the molecular mechanisms that govern PD-1 expression, we propose three aims designed to 1) define the cis- regulatory map and interactions at the PD-1 locus in antigen-specific cells following infection; 2) understand the interplay between NFATc1, Blimp-1 and STATs in regulating PD-1 during acute and viral infection conditions; and 3) to understand how the epigenetic silencer LSD1 controls PD-1 expression and DNA methylation at this locus. To investigate these aims, we have established a series of mouse lines that will conditionally delete the cis element CR-C, the transcription factor Blimp-1, or the epigenetic silencer LSD1 in activated CD8 T cells. We have established ex vivo methods to analyze the CD8 T cells and will incorporate an in vivo system of acute and chronic viral infection using LCMV to explore the mechanism by which these factors function to control PD-1. Ultimately our studies will elucidate the molecular genetic and epigenetic programs that control PD-1 expression and will provide new tools to manipulate PD-1 gene expression that could aid in the treatment of infection and cancer.