The role of SOCS1 repression by miR-155 in regulating immune responsiveness

描述（由申请人提供）：MicroRNA（miRNA）最近已被证明在调节免疫应答中起关键作用。其中，miR-155是免疫系统中最重要的miRNAs之一。遗传功能丧失研究表明，miR-155通过沉默各种免疫细胞群体中的多种靶标来控制免疫应答的多个方面。我们之前的工作表明Foxp 3驱动miR-155的高表达，从而通过诱导SOCS 1下调来促进Treg细胞的竞争适应性。其他小组进行的后续研究暗示了miR-155/SOCS 1轴在调节巨噬细胞对LPS诱导的内毒素耐受的反应性以及树突状细胞产生细胞因子中的作用。然而，由于miRNA通过靶向广泛的mRNA种类介导其作用，因此miR-155缺陷小鼠中的多种免疫应答相关表型可归因于除SOCS 1之外的miR-155靶基因的变化。在这里，我们提出了一个多方面的研究，采用遗传学，生物化学，免疫学的方法和整体动物实验，全面检查miR-155介导的SOCS 1调节的作用。首先，我们将检查SOCS 1缺陷/单倍不足和miR-155缺陷的联合作用，以观察所观察到的miR-155表型是否会因SOCS 1功能丧失而逆转。接下来，通过产生具有特异性破坏miR-155和SOCS 1基因之间相互作用的突变的新小鼠模型（SOCS 1 KI/KI小鼠），并将这些小鼠与miR-155缺陷小鼠进行比较，我们将能够分离miR-155对单个靶标的影响，并探索SOCS 1抑制在miR-155介导的免疫调节中的生物学意义。此外，由于miR-155强烈地参与促进自身免疫发展所需的炎症反应，因此在第二个具体目标中，我们将阐明miR-155在EAE中抑制SOCS 1的作用，EAE是一种成熟的多发性硬化症动物模型。SOCS 1 KI/KI小鼠的可用性提供了检查miR-155介导的SOCS 1抑制对控制自身免疫性疾病的贡献的机会。此外，使用T细胞转移实验以及混合BM嵌合体研究，将确定对miR-155介导的SOCS 1抑制在不同造血谱系中的各自作用的更精细的见解。最后，我们将研究miR-155介导的SOCS 1抑制促进EAE疾病表型的效应机制。拟议的研究将极大地扩展我们对miR-155介导的免疫调节中SOCS 1抑制的基本知识，并为调节人类健康和疾病中这种特定的miRNA靶点伙伴关系提供进一步的见解。

DESCRIPTION (provided by applicant): MicroRNA (miRNA), have been demonstrated recently to be pivotal in regulating immune responses. Among them, miR-155 is one of the most prominent miRNAs in the immune system. Genetic loss-of-function studies have demonstrated that miR-155 controls multiple aspects of the immune responses through silencing a wide range of targets in various immune cell populations. Our previous work suggested that Foxp3 drives high expression of miR-155 and, thereby promotes the competitive fitness of Treg cells by inducing SOCS1 down-regulation. Subsequent studies conducted by other groups have implied a role for the miR-155/SOCS1 axis in tuning macrophage responsiveness to LPS-induced endotoxin tolerance as well as cytokine production by dendritic cells. However, since miRNAs mediate their effects through targeting a broad range of mRNA species, diverse immune response related phenotypes in miR-155 deficient mice can be attributed to changes in miR-155 target genes other than SOCS1. Here, we propose a multifaceted study employing genetic, biochemical, immunological approaches and whole animal experimentation to comprehensively examine the role for miR-155-mediated SOCS1 regulation. First, we will examine the combined effects of SOCS1 deficiency/haploinsufficiency and miR-155 deficiency to see if aspects of the observed miR-155 phenotype are reversed by loss of SOCS1 function. Next, by generating a new mouse model with mutations specifically disrupting the interaction between miR-155 and SOCS1 gene (SOCS1KI/KI mice) and by comparing these mice to miR-155-deficient mice, we will be able to isolate the effects of miR-155 on a single target and to explore the biological significance of SOCS1 repression in miR-155-mediated immune regulation. Moreover, as miR-155 has been strongly implicated in promoting inflammatory responses required for the development of autoimmunity, in the second specific aim, we will elucidate the role of SOCS1 repression by miR-155 in EAE, a well-established animal model of multiple sclerosis. The availability of SOCS1KI/KI mice affords the opportunity to examine the contribution of miR-155-mediated SOCS1 repression to the control of autoimmune disease. Moreover, using T cell transfer experiments as well as mixed BM chimeras studies, more refined insights into the respective role of miR-155-mediated SOCS1 repression within different hematopoietic lineages will be determined. Finally, we will investigate effector mechanisms underlying miR-155-mediated SOCS1 repression in promoting EAE disease phenotype. The proposed studies will greatly extend our fundamental knowledge of SOCS1 repression in miR-155-mediated immune regulation and provide further insights into this specific miRNA-target partnership in regulating human health and disease.