Mechanisms Of Transcriptional Regulation in Memory lymphocyte Response and Aging

记忆淋巴细胞反应和衰老的转录调控机制

• 批准号: 7732316
• 负责人: Nan ping Peter Weng
• 金额: $ 44.21万
• 依托单位: NATIONAL INSTITUTE ON AGING
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7732316
• 关键词: Acetylation; Aftercare; Aging; Antigens; B Cell Proliferation; B-Lymphocytes; Binding; Bone Marrow; CD4 Positive T Lymphocytes; CD8B1 gene; Calculi; Cell Count; Cell Cycle; Cell Differentiation process; Cell division; Cells; Chromatin; Curcumin; Epigenetic Process; Exons; Gene Expression; Generations; Genes; Genetic Transcription; Goals; Histone Acetylation; Histones; Immune system; Immunologic Memory; In Vitro; Interphase Cell; Life; Lymphocyte; Lysine; Maintenance; Mature B-Lymphocyte; Mediating; Memory; Methods; MicroRNAs; Mitotic Cell Cycle; Molecular; Molecular Profiling; Mus; Numbers; Pathway interactions; Phase; Phenotype; Platelet Factor 4; Play; Post-Transcriptional Regulation; Property; Reporting; Rest; Role; Spleen; Staging; Stem cells; T memory cell; T-Lymphocyte; TNFRSF5 gene; Transcriptional Regulation; Vaccination; base; cohort; cyclin D2; day; granzyme B; histone acetyltransferase; in vivo; inhibitor/antagonist; interest; long term memory; memory CD4 T lymphocyte; memory process; pathogen; perforin; promoter; response; self-renewal; transcription factor

Immunological memory provides a fundamental basis of vaccination, yet it remains unresolved how the immune system achieves this long lasting enhanced function to re-encounters of the same pathogen. At the center of immunological memory are the memory lymphocytes that are capable of mounting a rapid and robust cellular response and have the stem cell like ability of self-renewal. These functional properties of memory T cells are acquired after activation of nave cells in which transcriptional regulation of specific genes plays a central role in the process of memory cell generation and subsequent maintenance. To understand the mechanism regulating the rapid effector function of memory CD8 T cells, we examined expression and chromatin state of a key transcription factor (eomesodermin, EOMES) and two of its targets: perforin (PRF1) and granzyme B (GZMB). Accessible chromatin associated histone 3 lysine 9 acetylation (H3K9Ac) was found significantly higher at the proximal promoter and the first exon region of all three genes in memory CD8 T cells than in nave CD8 T cells. Correspondingly, EOMES and PRF1 were constitutively higher expressed in memory CD8 T cells than in nave CD8 T cells at resting and activated states. In contrast, higher expression of GZMB was induced in memory CD8 T cells than in nave CD8 T cells only after activation. Regardless of their constitutive or inducible expression, decreased H3K9Ac levels after treatment with a histone acetyltransferase inhibitor (Curcumin) led to decreased expression of all three genes in activated memory CD8 T cells. These findings suggest that H3K9Ac associated accessible chromatin state serves as a corner stone for the differentially high expression of these effector genes in memory CD8 T cells. Thus, epigenetic changes mediated via histone acetylation may provide a chromatin memory for the rapid and robust transcriptional response of memory CD8 T cells. Highly activated CD4 T cell effectors can become resting after antigen clearance and go on to persist as long-lived memory cells. However, it is unclear when after antigen clearance effectors return to rest and acquire important memory properties. Here, we follow well-defined cohorts of CD4 T cells through the transitions from effector to memory by analyzing phenotype, functional properties, and gene expression profiles. We find that the transition from effector to memory is rapid in that effectors rested for only 3 days closely resemble long-lived memory cells in terms of phenotype and function. This is true for both Th1 and Th2 lineages, and occurs whether cells rest in vivo or in vitro, suggesting a largely default pathway. Finally, we find that the transition from effector to memory at the level of gene expression occurs in two stages: a rapid loss of expression of a myriad of effector-associated genes, and a more gradual gain of expression of a small cohort of genes uniquely associated with long-term memory cells. Further characterization of those genes preferentially expressed by long-term memory CD4 T cells may help to explain some of their unique features. Krppel-like factor 4 (Klf4) is a transcription factor and functions in regulating cell differentiation, cell growth, and cell cycle. Although Klf4 is expressed in lymphocytes, its function in lymphocytes is unknown. Here we report that the levels of Klf4 expression were low in pro-B cells and continuously increased in pre-B and in mature B cells. Upon activation, Klf4 was rapidly decreased in mature B cells after 2 hr of activation. A modest decrease in numbers of pre-B cells in bone marrow and mature B cells in spleen were observed in Klf4 deficient mice. In the absence of Klf4, fewer B cells entered S phase of the cell cycle and completed cell division in response to the engagement of BCR and/or CD40 in vitro. Furthermore, the delay in entering the cell cycle is associated with decreased expression of cyclin D2 in B cells that lack Klf4 expression. We then demonstrated that Klf4 directly bound to the promoter of cyclin D2 and regulated its expression. These findings demonstrate that Klf4 regulates B cell number and activation-induced B cell proliferation through directly acting on the promoter of cyclin D2.

免疫记忆提供了疫苗接种的基本基础，但仍未解决免疫系统如何实现这种持久的增强功能，以重新吸引同一病原体。 免疫记忆的中心是能够安装快速稳固的细胞反应并具有自我更新能力的干细胞的记忆淋巴细胞。在激活中殿细胞激活中，获得了记忆T细胞的这些功能特性，其中特定基因的转录调节在记忆细胞产生和随后的维持过程中起着核心作用。为了了解调节记忆CD8 T细胞快速效应函数的机制，我们检查了关键转录因子（Eomesodermin，eomes）的表达和染色质状态及其两个靶标：perforin（PRF1）和Granzyme B（GZMB）。 在记忆CD8 T细胞中所有三个基因的近端启动子和所有三个基因的第一个外显子区域发现，可访问染色质相关的组蛋白3赖氨酸9乙酰化（H3K9AC）明显高于Nave CD8 T细胞中的第一个外显子区域。 相应地，在记忆CD8 T细胞中，组成型Eomes和PRF1的表达高于在静息和激活状态下的含义CD8 T细胞中的Eomes和PRF1。 相反，仅在激活后，在记忆CD8 T细胞中诱导GZMB的表达更高。 无论其组成型或诱导表达如何，用组蛋白乙酰转移酶抑制剂（姜黄素）处理后H3K9AC水平降低，导致活化记忆CD8 T细胞中所有三个基因的表达降低。 这些发现表明，H3K9AC相关的可访问染色质状态是记忆CD8 T细胞中这些效应基因差异表达的角石。 因此，通过组蛋白乙酰化介导的表观遗传学变化可能为记忆CD8 T细胞的快速转录反应提供染色质记忆。 高度激活的CD4 T细胞效应子可以在抗原清除后静止，并继续持续使用长寿命的记忆细胞。 但是，目前尚不清楚抗原清除效应器何时恢复休息并获得重要的内存属性。 在这里，我们通过分析表型，功能特性和基因表达谱通过从效应子到记忆的过渡遵循明确定义的CD4 T细胞队列。 我们发现，从表型和功能方面，效应子仅在效应子到内存的过渡迅速3天。 对于TH1和TH2谱系都是如此，并且发生在体内或体外，都会发生细胞，这在很大程度上表明默认途径。 最后，我们发现在基因表达水平上从效应子到记忆的过渡分为两个阶段：迅速丧失了与效应子相关的基因的表达迅速丧失，以及与长期记忆细胞独特相关的小基因的表达的逐渐逐渐增加。 通过长期记忆CD4 T细胞优先表达的那些基因的进一步表征可能有助于解释它们的某些独特特征。 Krppel样因子4（KLF4）是转录因子，并且在调节细胞分化，细胞生长和细胞周期方面的功能。 尽管KLF4在淋巴细胞中表达，但其在淋巴细胞中的功能尚不清楚。 在这里，我们报告说，pro-B细胞中KLF4表达的水平较低，并且在成熟的B细胞中不断增加。 激活后，激活2小时后，成熟的B细胞中KLF4迅速降低。 在KLF4缺乏的小鼠中观察到骨髓和成熟的B细胞中BED-B细胞数量的适度减少。 在没有KLF4的情况下，较少的B细胞进入了细胞周期的S期，并响应于BCR和/或CD40体外的响应而完成细胞分裂。 此外，进入细胞周期的延迟与缺乏KLF4表达的B细胞中细胞周期蛋白D2的表达降低有关。 然后，我们证明KLF4直接与Cyclin D2的启动子结合并调节其表达。 这些发现表明，KLF4通过直接作用于细胞周期蛋白D2的启动子来调节B细胞数和激活诱导的B细胞增殖。