miR-143/145 cluster 在I型干扰素介导免疫反应中的作用及其表观遗传机制研究

Type I interferons (IFNs) are cytokines that are important for the regulation of immune responses. IFNs-mediated immunity and the underlying mechanism have attracted much more attention since their discovery. miRNAs have recently emerged as posttranscriptional gene regulators, and their important roles in immunology have been widely accepted and required further in-depth characterization. The present study concentrates exactly on the connection between the two above kinds of regulators. Through miRNA microarray，we found that miR-143/145 cluster was dramatically decreased upon direct IFNs signal in mouse macrophages. And miR-145 could enhance transcription activity of Il10 promoter via targeting histone deacetylase HDAC11, and subsequently increase IL-10 production induced by IFN-beta. This project intends to further confirm the roles miR-143/145 cluster might play in IFNs-mediated immunity, especially the anti-inflammatory resonses, with ectopic expression cell lines and transgenetic mice. Secondly, the intact effects of miR-143/145 cluster on type I IFN signaling and the detailed mechanism will be clarified. In addition, we will also investigate the mechanism in the regulation of miR-143/145 cluster expression triggered by IFNs at miRNA transcriptional level, as well as the individual steps in the miRNA processing. The study will clarify the novel mechanism in IFNs-mediated immunity via posttranscriptional level, lead to new explanation in IFNs-mediated anti-inflammatory responses, and further enrich miRNA functions in immune response and its regulation by immune system.

I型IFNs,一类重要的细胞因子，其介导的免疫反应及其调控机制长期受到广泛关注。miRNAs，一类新兴转录后调控因子，其在免疫学中的重要作用被广泛接受并继续深入。该研究正是着眼于这两者的相互调控。前期实验通过rmIFNbeta刺激小鼠巨噬细胞的miRNA芯片得到I型IFNs调控的miR-143/145 cluster，其中下调的miR145可通过HDAC11参与IFN介导的IL-10的表达。后续将通过构建高表达细胞系或转基因老鼠确定miR-143/145在I型IFN介导的抗炎反应中的作用，并全面筛查该cluster对I型IFNs信号通路和功能的影响并确定作用机制。同时在miRNA转录及其加工成熟的各环节研究IFN下调该cluster的分子机制。本项目的完成将阐明I型IFN通过miRNA发挥功能的新机制，为IFN的抗炎机制作出新解释，进一步丰富miRNA在免疫反应中的功能和被免疫调控的机制。

microRNAs（miRNAs）是一类参与基因转录后负向调节的小分子非编码RNA，其在天然免疫应答中重要的调控功能近年来逐渐被证实。我们以往的研究提示水疱性口炎病毒（VSV）感染的巨噬细胞中miR-143 / 145簇的表达水平呈现显著下调，而该miRNA簇在天然免疫应答调控以及抗病毒天然免疫应答中的功能尚不清楚。第一部分研究中，我们证实了天然免疫应答过程中诱导产生的IFN-I可下调miR-145的表达，从而缓解miR-145对其靶标分子HDAC11的转录后抑制；表达上调的HDAC11特异性地促进 Il10基因的转录抑制，进而实现IL-10表达的负向调控。我们的发现揭示了天然免疫应答中IL-10表达调控网络中一条新的由IFN-I- miR-145- HDAC11介导的负向反馈环路，为启动和维持适度的天然免疫应答而存在的错综复杂的调控网络增添了新的机制和新的认识。第二部分研究中，我们证实了miR-143通过靶向作用于GABARAPL1从而抑制病毒entry过程，巨噬细胞内病毒复制相应减弱，继而影响巨噬细胞对病毒RNA信号的识别及其后续的抗病毒天然免疫应答。我们的研究可能揭示天然免疫细胞识别病毒核酸信号上游的生物学过程，并可能为干扰素非直接依赖的抗病毒机制增添新的认识。