MicroRNA Function in the Immune System

描述(由申请人提供)：炎症反应是人体对感染最重要的防御之一。炎症的起始者之一是细菌脂多糖(LPS)。我们早在几年前就发现，内毒素会在巨噬细胞中诱导3个microRNA。这些小RNA可以对蛋白质水平产生巨大的调控影响。因此，我们一直在从不同的角度描述这3个RNA的特征，这项请求是为了获得资金来深入研究这些RNA。其中一种微小RNA被认为与癌症的诱发有关，并可能在炎症和癌症之间提供联系。我们还计划研究另一个microRNA家族，因为它与免疫细胞成熟有潜在的关系。计划中的研究利用了当今操纵老鼠基因的能力。因此，过度表达和敲除研究将使我们能够检查过多或不过多的特定microRNAs对小鼠生理的影响。过度表达的研究将通过将表达microRNAs的基因整合到病毒载体中，用这些载体感染骨髓干细胞，并将感染的细胞转移到受到致命辐射的宿主鼠身上来完成。我们将使用高分辨率表面标记分析来表征这些microRNAs在特定免疫细胞亚群的产生和行为中的作用。在这项工作中，我们还将使用在细胞中的体外表达，通过向细胞传递基因的载体。MicroRNA是从前体加工而来的，我们发现加工本身是受调控的。我们计划研究这一规定是如何实现的。为了了解这些微小RNA是如何工作的，我们将描述它们调控的目标基因的特征。这涉及到生物信息学来寻找候选基因，确定其表达对特定microRNA敏感的基因，然后研究这些基因的作用。对于可能参与免疫细胞发育的microRNA家族，我们怀疑它可能控制着产生抗体的细胞分化的最后阶段。因此，我们将集中精力研究免疫细胞发育的那个阶段，重点是一种通常与保护基因组有关的蛋白质--p53的可能作用。与公共健康相关：科学家长期以来一直认为免疫系统是由蛋白质控制的。我们最近的工作表明，一些小的RNA分子是炎症和免疫反应的控制者。我们计划研究这种RNA如何发挥作用，重点放在癌症和炎症之间的关系上。微生物感染和癌症是全球人类疾病的主要原因之一。因此，我们必须继续界定这些毁灭性问题背后的分子基础。最近，microRNAs作为一类新的基因表达调控因子出现，与免疫系统调节和癌症生物学有关。我们的团队已经发现，少数miRNAs是由对感染的先天免疫反应有效地诱导的，因此建议表征这些miRNAs在宿主防御感染和肿瘤发生中的作用。

DESCRIPTION (provided by applicant): The inflammatory response is one of the body's most important defenses against infection. One initiator of inflammation is bacterial lipopolysaccharide (LPS). We found some years ago that LPS will induce in macrophages 3 microRNAs. These are small RNAs that can have huge regulatory influences on protein levels. We have therefore been characterizing these 3 RNAs from various points of view and this request is for funds to study these RNAs in depth. One of the microRNAs has been linked to cancer induction and may provide a link between inflammation and cancer. We have also included plans to study another microRNA family because of its potential relationship to immune cell maturation. The planned studies take advantage of today's ability to manipulate the genetics of mice. Thus, overexpression and knockout studies will allow us to examine the consequences to mouse physiology of too much or none of the particular microRNAs. The overexpression studies will be done by incorporating into viral vectors genes that express the microRNAs, infecting bone marrow stem cells with these vectors and transferring the infected cells to lethally irradiated host mice. We will use high resolution surface marker analysis to characterize the role of these microRNAs in the generation and behavior of particular subsets of immune cells. In this work, we will also use in vitro expression in cells through vectored delivery of genes to the cells. MicroRNAs are processed from precursors and we have found that the processing itself is regulated. We plan to examine how this regulation is achieved. To understand how these microRNAs work we will characterize the target genes that they regulate. This involves bioformatics to find candidates, determining the genes whose expression is sensitive to a particular microRNA and then study of the role of those genes. For the microRNA family that may be involved in immune cell development, we suspect that it could be controlling the final stage of differentiation of the cells that make antibodies. We will therefore concentrate on examining that stage of immune cell development with an emphasis on the possible role of a protein usually associated with protecting the genome, p53. PUBLIC HEALTH RELEVANCE: Scientists have long thought that the immune system is controlled by proteins. Our recent work has implicated some small RNA molecules as controllers of inflammatory and immune responses. We plan to examine how such RNAs might work with an emphasis on the relationship between cancer and inflammation. Microbial infections and cancer are among the leading causes of human diseases worldwide. Therefore, it is imperative that we continue to define the molecular basis underlying these devastating problems. Very recently, micro-RNAs have emerged as a novel class of gene expression regulators that are implicated in both immune system regulation and cancer biology. Our group has found that a small number of miRNAs are potently induced by the innate immune response to infection, and therefore propose to characterize the roles of these miRNAs in host defense against infection and tumorigenesis