E3泛素连接酶FBXW7调节病毒诱导的Ⅰ型干扰素表达及其机制研究

发布时间：2018-07-10 05:03

本文选题：抗病毒免疫 + E3泛素连接酶　；参考：《浙江大学》2015年博士论文

【摘要】：天然免疫细胞通过模式识别受体(pattern recognition receptors,PRRS)识别病原微生物相关模式启动天然免疫反应抵抗病原微生物的入侵。其中维甲酸诱导基因Ⅰ样受体(Retinoic acid-inducible gene I like receptor,RLRs)通过识别病毒 RNA,传递下游信号通路,活化了转录因子IRF3/7,NF-κB,AP-1,导致f型干扰素和炎症因子的表达。I型干扰素能够与细胞膜上的干扰素受体(interferon receptor,IFNR)结合,活化了细胞内信号通路,诱导表达具有抑制病毒复制和感染功能的干扰素刺激基因(interferonstimulationgene,ISG)。因此I型干扰素,在抗病毒天然免疫反应中具有非常重要的作用。蛋白质的泛素化在天然免疫细胞识别,清除病原体和细胞信号传导中发挥着非常关键的作用。而在蛋白质发生泛素化过程中,E3泛素连接酶负责特异性识别靶蛋白,并将不同的泛素链连接到靶蛋白上,发挥着不同的功能。E3泛素连接酶FBXW7在肿瘤的发生发展,脂类代谢,细胞增殖和分化,维持干细胞的稳态发挥着重要的作用,然而FBXW7在病毒天然免疫反应中的作用几乎不清楚。我们研究发现,髓系细胞中特异性敲除FBXW7基因的小鼠(Lysm+FBXW7f/f mice)对水疱性口炎病毒(Vesicular Stomatitis Virus,VSV)感染更加敏感,VSV病毒复制更加活跃。敲除FBXW7的巨噬细胞和树突状细胞在VSV感染下,VSV-G mRNA明显升高。我们发现这一现象与I型干扰素的产生的差异相关。敲除FBXW7的巨噬细胞和树突状细胞在VSV和H1N1感染下显著减少了 I型干扰素的产生,III而过表达FBXW7,能够显著地促进I型干扰素的产生。进一步的研究发现FBXW7能够促进转录因子IRF3的活化,进而增强了Ⅰ型干扰素的产生。其作用机制是FBXW7在病毒感染作用下,能够与SHP2结合。而SHP2是RIG-I信号通路中关键的负向调控分子,能够显著抑制Ⅰ型干扰素的产生。FBXW7通过识别SHP2的降解子序列,催化SHP2的91位点的赖氨酸(91K)发生K48连接的泛素化,使SHP2通过蛋白酶体途径发生降解,促进Ⅰ型干扰素的产生。本研究揭示了 FBXW7在抗病毒天然免疫中发挥着重要的调控功能,可为深入认识天然免疫的调节机制提供新的观点并可能为治疗感染性疾病提供新的思路和理论依据。
[Abstract]:Innate immune cells recognize pathogenic microorganisms by pattern recognition receptor (pattern recognition receptor / PRRS) and initiate innate immune response to the invasion of pathogenic microorganisms. Retinoic acid-inducible gene I like receptor (RLRs) transduces downstream signaling pathways by recognizing viral RNAs. Activation of transcription factor IRF3 / 7 NF- 魏 BmAP-1resulted in the expression of interferon type f and inflammatory factor I, which could bind to the interferon receptor (IFNR) on the cell membrane and activate the intracellular signaling pathway. Interferon stimulating ISG (ISG) was induced to express interferon stimulating gene (ISG) which can inhibit viral replication and infection. Therefore, interferon I plays a very important role in anti-viral innate immune response. Protein ubiquitin plays a key role in innate immune cell recognition, pathogen clearance and cell signal transduction. In the process of protein ubiquitin ligation, E3 ubiquitin ligase is responsible for the specific recognition of target proteins, and links different ubiquitin chains to target proteins, which play different functions. E3 ubiquitin ligase FBXW7 plays a different role in tumorigenesis and development and lipid metabolism. Cell proliferation and differentiation and maintenance of stem cell homeostasis play an important role, but the role of FBXW7 in the innate immune response of virus is almost unknown. We found that Lysm FBXW7fr / f mice was more sensitive to vesicular stomatitis virus infection than Lysm FBXW7 gene knockout mice (Lysm FBXW7f / f mice). Macrophages and dendritic cells knockout FBXW7 were significantly increased in VSV-G mRNA under VSV infection. We found that this phenomenon was related to the difference in the production of type I interferon. The knockout macrophages and dendritic cells of FBXW7 significantly reduced the production of interferon type I and overexpression of FBXW7 under VSV and H1N1 infection, which could significantly promote the production of interferon type I. Further studies have shown that FBXW7 can promote the activation of transcription factor IRF3 and further enhance the production of interferon type I. The mechanism is that FBXW7 can bind to SHP2 in the presence of virus infection. SHP2 is a key negative regulatory molecule in the RIG-I signaling pathway, which can significantly inhibit the production of interferon type I. FBXW7 catalyzes the K48-linked ubiquialization of lysine (91K) at the 91 site of SHP2 by recognizing the degradation subsequence of SHP2. SHP2 was degraded by proteasome pathway and the production of interferon type I was promoted. This study revealed that FBXW7 plays an important regulatory role in antiviral innate immunity, which can provide a new viewpoint for further understanding the regulatory mechanism of innate immunity and may provide new ideas and theoretical basis for the treatment of infectious diseases.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：R392

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