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

描述(申请人提供)：微RNA(MiRNA)，最近已被证明在调节免疫反应中起关键作用。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通过沉默不同免疫细胞群体中的广泛靶点来控制免疫反应的多个方面。我们以前的工作表明，Foxp3可以促进miR-155的高表达，从而通过诱导SOCS1下调来促进Treg细胞的竞争适合度。其他研究小组随后进行的研究表明，miR-155/SOCS1轴在调节巨噬细胞对内毒素耐受的反应以及树突状细胞产生细胞因子方面发挥了作用。然而，由于miRNAs通过靶向广泛的mRNA物种来调节其作用，miR-155缺陷小鼠中与免疫反应相关的不同表型可以归因于除SOCS1以外的miR-155靶基因的变化。在这里，我们提出了一项多方面的研究，采用遗传学、生化、免疫学和全动物实验的方法来全面研究miR-155介导的SOCS1调节的作用。首先，我们将研究SOCS1缺乏/单倍体不足和miR-155缺乏的联合影响，看看所观察到的miR-155表型的某些方面是否会因SOCS1功能的丧失而逆转。接下来，通过建立一个新的小鼠模型(SOCS1KI/KI小鼠)，并将这些小鼠与miR-155缺陷小鼠进行比较，我们将能够分离出miR-155对单个靶点的影响，并探索SOCS1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与促进自身免疫发展所需的炎症反应密切相关，在第二个特定目标中，我们将阐明miR-155抑制SOCS1在EAE中的作用，EAE是一种公认的多发性硬化症动物模型。SOCS1KI/KI小鼠的出现为研究miR-155介导的SOCS1抑制在控制自身免疫性疾病中的作用提供了机会。此外，利用T细胞转移实验和混合骨髓嵌合体研究，将确定更精细的洞察力，以了解miR-155介导的SOCS1抑制在不同造血谱系中的各自作用。最后，我们将研究miR-155介导的SOCS1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SOCS1抑制的基础知识，并为进一步了解这一特定的miRNA-靶向伙伴关系在调节人类健康和疾病中的作用提供进一步的见解。

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.