去泛素化酶USP39在天然免疫应答及感染性疾病中的调控作用与机制研究

The innate immune responses trigged by pathogens or exogenous ligands through pattern recognition receptors, which are tightly regulated by various molecules. Deubiquitinases regulate the stability and activity of ubiquitination regulatory protein involved in the immune response. However, little attention was paid to the roles of deubiquitinases in innate immunity and inflammatory diseases. By luciferase reporter gene screening, we found USP39 positive regulation of NF-κB and RIG-I signaling pathway. In the preliminary experiments of this case，We found that in mice peritoneal macrophages interference USP39, reduced production of LPS or CpG or VSV induced TNF-α and IFN-β; interference USP39 in human THP-1, or USP39+/- mouse peritoneal macrophages by VSV infection induced IFN-β expression was significantly reduced and antiviral capacity decreased, suggesting that USP39 may positively regulates virus triggered innate immune response. This study intends to investigate the function of USP39 against bacterial and viral induced innate immune responses in vitro and in vivo, study on molecular regulation mechanism of protein or mRNA mature level of innate immune signal molecules by USP39, and provide new ideas for the treatment of infectious diseases and inflammatory autoimmune diseases.

病原体或外源性配体通过模式识别受体触发的天然免疫应答受到多种分子的严密调控。去泛素化酶通过去泛素化作用调控蛋白的稳定性及活性参与免疫应答反应，然而去泛素化酶在天然免疫应答中的功能及非去泛素化调控机制研究较少。通过荧光素报告基因筛选，我们发现USP39可正向调控NF-κB和RIG-I信号通路。预实验显示在小鼠腹腔巨噬细胞中干扰USP39后，LPS、CpG 或 VSV 诱导的TNF-α、IFN-β产生减少；在人THP-1中干扰USP39，或USP39+/-小鼠腹腔巨噬细胞经VSV感染诱导的IFN-β的表达显著减少且抗病毒能力下降，提示USP39可能正向调控病毒触发的天然免疫应答反应。本研究拟在体内外探讨USP39 对细菌和病毒诱导的天然免疫反应的调控功能，探讨USP39对天然免疫信号关键分子在蛋白或mRNA成熟水平的分子调控机制，为感染性疾病和炎症性自身免疫病的治疗提供新思路。

固有免疫是机体抵抗病原微生物的第一道防线。本研究发现去泛素化酶USP39可促进TLR配体、RNA病毒等诱导的固有免疫应答。项目重点研究了USP39在抗RNA病毒固有免疫应答中的作用。RIG-I是识别RNA病毒并触发抗病毒固有免疫应答的关键分子。本研究证实RNA病毒可下调巨噬细胞USP39的表达；USP39促进RIG-I mRNA剪切成熟，进而稳定的RIG-I蛋白，从而正向调控RNA病毒感染诱导的RIG-I的活化、IRF3的磷酸化及I型干扰素的产生。通过构建USP39巨噬细胞条件敲除小鼠，发现USP39特异性敲除小鼠抗VSV病毒感染能力显著减弱。该研究明确了USP39在抗病毒固有免疫反应中的调控作用及其调控RIG-I信号途径的相关分子机制，发现调控RIG-I mRNA剪切成熟的新方式，为深入了解抗病毒固有免疫反应提供新思路。