Role of microRNAs in regulatory T cell-mediated immunological tolerance and T cel

描述(申请人提供)：众多微RNA(MiRNA)，一类短的调节性非编码RNA，以其在器官发育、细胞分化、动态平衡和功能中的作用而闻名，最近被证明在调节免疫反应中起关键作用。我们以前已经证明了miRNA通路在控制调节性T(Treg)细胞的稳态和功能中起着不可或缺的作用。在Treg细胞高表达的miRNAs中，miR-155和miR-146a分别在维持Treg细胞的正常动态平衡和更重要的是调节其对Th1炎症的抑制作用方面发挥着关键作用。然而，由于携带缺乏miRNA的Treg细胞的小鼠的疾病表型的复杂性和严重性不能完全归因于上述单个miRNAs的丢失，因此需要进一步阐明控制Treg细胞生物学其他功能所必需的其他miRNAs。与上面描述的miR-155和miR-146a一样，miR-23簇在Treg细胞中至少部分地以Foxp3依赖的方式高度上调。此外，在Treg细胞和Tcon细胞中，miR-23簇的表达差异在激活后变得更大，因为它们在Treg细胞中进一步上调，而在Tcon细胞中下调。在这里，我们提出了一项多方面的研究，采用遗传学、生化、免疫学和整体动物实验的方法，全面研究miR-23簇介导的免疫调节的分子和细胞机制。首先，通过产生携带miR-23簇的条件等位基因的小鼠，这种功能丧失的方法将使我们能够检查miR-23簇在生理和自身免疫环境中调节Treg细胞介导的免疫耐受中的作用。接下来，立即获得携带整个miR-23a簇的条件性过表达转基因的小鼠以及该簇中的单个miRNA成员，将为系统地研究miR-23簇在不同环境中控制T细胞免疫的作用提供机会。最后，我们将通过识别以miR-23簇依赖的方式调节的基因和通过识别由miR-23簇直接控制的靶点来探索miR-23簇依赖的免疫调控的潜在分子机制。所提出的研究将极大地扩展我们对miRNA介导的免疫调节的基础知识，并为开发操纵Treg细胞和效应器T细胞功能作为治疗人类免疫性疾病的新的治疗方法提供进一步的见解。

DESCRIPTION (provided by applicant): Numerous microRNA (miRNA), a class of short regulatory non-coding RNAs known for their role in organ development, cellular differentiation, homeostasis, and function, have been recently demonstrated to be pivotal in regulating immune responses. We have previously shown an indispensable role of the miRNA pathway in controlling regulatory T (Treg) cell homeostasis and function. Among miRNAs highly expressed in Treg cells, miR-155 and miR-146a play pivotal roles in maintaining normal Treg cell homeostasis and more importantly regulating their suppressor function to Th1 inflammation, respectively. Nonetheless, because the complexity and the severity of the disease phenotypes in mice harboring Treg cells devoid of miRNA cannot be attributed entirely to the loss of aforementioned individual miRNAs, additional miRNAs essential for controlling other features of Treg cell biology require further elucidation. Like miR-155 and miR-146a described above, miR-23 clusters were found to be highly upregulated in Treg cells at least partially in a Foxp3 dependent manner. Moreover, the differences in the expression of miR-23 clusters between Treg cells and Tcon cells became even larger upon activation as they were further upregulated in Treg cells while downregulated in Tcon cells. Here, we propose a multifaceted study employing genetic, biochemical, immunological approaches and whole animal experimentation to comprehensively examine the molecular and cellular mechanisms underlying miR-23 cluster-mediated immune regulation. First, by generating mice harboring conditional alleles of miR-23 clusters, this loss-of-function approach will allow us to examine the role of miR-23 clusters in regulating Treg cell-mediated immunological tolerance in both physiological and autoimmune settings. Next, the immediate availability of mice harboring conditional over-expressing transgenes of the whole miR-23a cluster as well as individual miRNA member within the cluster will afford the opportunity to systematically examine the role of miR-23 cluster in controlling T cell immunity in various settings. Finally, we will explore the putative molecular mechanisms underlying miR-23 cluster-dependent immune regulation through identification of genes that are regulated in miR-23 cluster-dependent manner and through identification of targets that are directly controlled by miR-23 clusters. The proposed studies will greatly extend our fundamental knowledge of miRNA-mediated immune regulation and provide further insights into the development of strategies to manipulate Treg cell and effector T cell function as novel therapeutic approaches for treating human immunological diseases.