【作者】 李涛；

【导师】 张学敏；

【作者基本信息】 中国人民解放军军事医学科学院 ， 细胞生物学， 2010， 博士

【摘要】 单核细胞(Monocyte)是体内一类重要的无颗粒白细胞,单核细胞作为巨噬细胞(Macrophages)和树突状细胞(Dendritic cells)的前体,与巨噬细胞共同构成了机体先天免疫系统的重要部分。巨噬细胞分化和功能异常,通常与包括肿瘤在内的一系列疾病有关。然而,单核-巨噬细胞分化过程中诸多分子事件的发生以及其调控原理,我们仍然知之甚少。在这方面的进一步深入研究将无疑会帮助我们认识和解决诸如肿瘤、自身免疫疾病等一系列重大疾病。MicroRNAs自1993年被初次发现以来,迅速成为了研究者们研究的热点,人们渐渐意识到MicroRNA在包括细胞分化等许多生物学过程中起着关键作用。特别是在免疫细胞分化和功能的调节中发挥了引人注目的作用。本研究中,我们以人的原代单核细胞为模型,揭示了在单核-巨噬细胞分化过程中,MicroRNA——miR-223,miR-15a和miR-16通过调节非经典NF-κB信号通路的激活,进而在调控巨噬细胞的功能方面起到了至关重要的作用。我们发现,miR-223,miR-15a和miR-16在单核-巨噬细胞分化过程中显著下调。生物信息学分析发现NF-κB信号通路的重要激酶IKKα是这三个micoRNA的共同靶基因。进一步的研究证实了在巨噬细胞分化的过程中,这些microRNA表达水平的变化显著上调了IKKα蛋白水平。更重要的是,在巨噬细胞中高表达水平的IKKα,NIK以及信号分子TRAF2的降解介导了p100持续性地被剪切成p52。然而,由于在巨噬细胞中,NF-κB2转录因子的转录调节亚基RelB的蛋白表达水平极低,因此,高表达水平的p52对非经典NF-κB通路靶基因的表达起抑制作用。当巨噬细胞受到炎性因子刺激后,如LPS,随着细胞内RelB蛋白的快速补充,p52介导的这种抑制作用,迅速转为促进作用,促进非经典NF-κB通路靶基因的表达。综上所述,我们的结果揭示了在单核-巨噬细胞分化的过程中,特定microRNA的变化通过调控非经典NF-κB信号通路的激活使分化成熟的巨噬细胞处在一种抑制性的自我保护状态,并为机体应对后续的炎性刺激做好了准备。更多还原

【Abstract】 Monocytes are a type of the nongranular leukocytes, which supply peripheral tissues with macrophages and dendritic cells (DC) precursors and constitute an important part of the innate immune system. It has been more and more uncovered by emerging publications that deregulation of macrophage functions and differentiation is often involved in many types of diseases including cancer. However, the molecular events happened during monocyte-macrophage differentiation are still largely unknown. Any further knowledge about this important process will definitely give more in sight to understand the differentiation of monocytes and will provide more therapeutic opportunity to treat cancer and other major related diseases.MicroRNAs became the focus of many researchers since it has been discovered at 1993. Emerging evidence suggested that microRNAs are important component of immune cell differentiation and function.In this study with human primary monocytes and macrophages, we show that during monocyte-macrophage differentiation, microRNAs, miR-223, miR-15a and miR-16 play a crucial role in regulating macrophage function by modulating non-canonical NF-κB signaling pathway. We found that during the differentiation of macrophage, these microRNAs are dramatically decreased. Bioinformatics analysis suggested that the IκB protein kinase, IKKαis the sharing target of these three microRNAs. We demonstrated that the levels of these microRNAs determine the expression amounts of IKKαin monocyte and macrophages respectively. Importantly, the high IKKαexpression in junction with NIK stabilization leads to an increased level of p52. Due to the absence of RelB expression in untreated macrophages, the high level of p52 represses target genes of the non-canonical NF-κB pathway. However, this inhibitory effect will be turned to promotional effect when the cells were further challenged by LPS. Thus, our data suggested during the differentiation of macrophage, the changes of certain microRNAs likely prevent macrophage hyperactive and yet prime the macrophage for a robust response to proinflammatory stimuli.更多还原