RNA结合蛋白介导的新型上皮细胞免疫抑制通路的研究

Cellular inflammatory responses require a series of intricate regulations. This proposal seeks to define the posttranscriptional mechanisms that control cellular inflammatory response and prevent tissue damage due to excessive inflammation. Because of the important of RNA-binding proteins in posttranscriptional gene regulation, the goal for this application is to investigation the role of KSRP-mediated mRNA stability in the coordinated expression of inflammatory effecter proteins that are potentially harmful to host tissues in epithelial cells. Sustained expression of pro-inflammatory proteins has been implicated in cellular injury in a diverse range of inflammatory diseases, including inflammatory hepatobiliary diseases. KSRP (the KH-type splicing regulatory protein) is an RNA binding protein that induces mRNA decay through binding to the AU-rich region of 3'UTR mRNA. Based on preliminary data, this proposal tests the novel central hypothesis that miRNA-mediated posttranscriptional mechanisms control expression of KSRP in liver epithelial cells, and upregulation of KSRP destabilizes iNOS and COX-2 mRNAs, providing negative regulation to epithelial cell inflammatory responses. Current and comprehensive molecular, biochemical, and cell biological approaches will be employed to ascertain how interferon-gamma (IFN-γ) induce KSRP expression in liver epithelial cells, and to clarify KSRP's relevance to the feedback regulation of epithelial inflammatory response. This proposal has two specific aims. First, it will test the hypothesis that IFN-γ regulates KSRP expression to destabilize iNOS and COX-2 mRNAs through downregulating miRNAs. Second, it will test the hypothesis that KSRP-mediated destabilization of iNOS and COX-2 mRNAs provides negative regulation to epithelial inflammatory responses. The proposal is innovation because it tests new concepts for KSRP-mediated mRNA stability and its involvement in the regulation of epithelial cell inflammatory responses. The project's significance is that it may reveal a new mechanism by which liver epithelial cells maintain homeostasis in response to inflammatory stimuli. The information resulting from these studies could identify new therapeutic strategies not only for inflammatory diseases, but also for other inflammatory diseases in general.

机体内的免疫反应受到一系列精细调控。过强的免疫应答会造成机体的损伤。转录后调控在免疫功能因子的调控中起着重要的作用，需要RNA结合蛋白的参与。KH-型剪接调控蛋白（KSRP）是一个RNA结合蛋白，可以调控一些免疫功能因子的mRNA稳定性。本文主要是研究KSRP介导的mRNA稳定性在上皮细胞免疫应答的精细调控中的作用。该研究包括将在肝脏和胆管上皮细胞及急性肝损伤小鼠模型中，证明通过miRNA调节的KSRP的表达，KSRP通过转录后调控机制，即与mRNA 3'UTR上的AREs结合，调节一些免疫功能因子的表达，从而形成一个负反馈调控环路，抑制过强的免疫应答。研究的新颖性在于证实在上皮细胞免疫中存在的一种新的免疫调节机制；阐明一种针对免疫刺激上皮细胞维持内部稳态新的机制。

机体内的免疫反应受到一系列精细调控。过强的免疫应答会造成机体的损伤。转录后调控在炎症相关因子的调控中起着重要的作用。本课题通过对细胞水平和小鼠模型的研究中发现，miR-27b和KH-型剪接调控蛋白（KSRP）参与调控一些炎症因子的表达，如CX3CL1和TGF-β。其作用机制通过miR-27b调控KSRP的表达，KSRP与CX3CL1和TGF-β3’UTR 上的AREs 结合，影响其mRNA的稳定性，从而形成一个负反馈调控环路，抑制过强的免疫应答。研究的新颖性在于证实在上皮细胞免疫中存在的一种新的免疫调节机制；阐明一种针对免疫刺激上皮细胞维持内部稳态新的机制，并将会为肝脏相关疾病的治疗理论依据。研究成果部分发表在2015年的《Scientific Reports》上和2017年的《The Journal of Immunology》。