Independent Cycling and Differentiation in CD4+ T cells

描述（由申请人提供）：活化的T细胞既经历增殖，导致克隆扩增，也经历分化，产生效应功能。这些现象在许多免疫反应中同时发生，但它们是如何联系在一起的呢？一些已发表的数据表明，CD4+ T细胞的分裂次数与分化和效应细胞因子的合成密切相关，提示分化与细胞分裂周期之间存在分子机制耦合。其他已发表的数据，包括我们自己的数据，表明细胞分裂和分化是不耦合的。我们在一个过继转移模型中开发的新的初步数据，在该模型中，CFSE染料用于计数细胞分裂周期，也有利于CD4+ T细胞增殖和分化的独立性。为了适应所有的数据，我们将细胞周期进入S期和编码效应细胞因子的基因的激活视为不同的、不相关的概率事件。为了探索这一想法，我们将使用一个模型，其中CD4+ T细胞中效应细胞因子（ifn - γ， IL-4和IL-5）的合成独立于增殖。在特异性目标1中，我们将确定T细胞激活的条件，导致非循环但有功能的效应T细胞。在特异性目标2中，我们将定义这些细胞的细胞周期调节状态，并验证由于一种或多种周期蛋白依赖性激酶抑制剂的作用，它们在周期的g1期被阻止的假设。在特异性目标3中，我们将确定这些非循环但具有功能效应的CD4+ T细胞是否正在经历Th1和Th2途径的谱系承诺。这些研究将阐明CD4+ T细胞活化、细胞分裂、分化和谱系承诺之间的关系。

DESCRIPTION (provided by applicant): Activated T cells undergo both proliferation, which results in clonal expansion, and differentiation, resulting in effector function. These phenomena occur together in many immune responses, but how are they linked? Some published data show that the number of divisions undergone by a CD4+ T cell is tightly correlated with differentiation and the synthesis of effector cytokines, suggesting that a molecular mechanism couples differentiation to cell division cycles. Other published data, including our own, suggest that cell division and differentiation are uncoupled. Our new preliminary data, developed in an adoptive transfer model in which the dye CFSE was used to count cell division cycles, also favor the independence of proliferation and differentiation in CD4+ T cells. To accommodate all of the data, we view the entry into S phase of the cell cycle, and the activation of the genes that encode effector cytokines, as distinct, unlinked probabilistic events. To explore this idea, we will use a model in which the synthesis of effector cytokines (IFN-gamma, IL-4 and IL-5)in CD4+ T cells occurs independent of proliferation. In Specific Aim 1, we will determine the conditions of T cell activation that result in non-cycling but functional effector T cells. In Specific Aim 2, we will define the state of cell cycle regulation in these cells, and test the hypothesis that they are arrested in the G 1 phase of the cycle, due to the action of one or more cyclin-dependent kinase inhibitors. In Specific Aim 3, we will determine whether these non-cycling but functional effector CD4+ T cells are undergoing lineage commitment to the Th1 and Th2 pathways. These studies will clarify the relationships between activation, cell division, differentiation, and lineage commitment in CD4+ T cells.