去泛素相关蛋白Gm114在肠道稳态和炎症反应调控机制的研究

NF-κB信号通路在免疫反应和细胞存活、分化和增殖中起着重要并且保守的功能。蛋白的泛素和去泛素在NF-κB信号通路活性的平衡和适时终止至关重要。蛋白的聚集参与调控多种生命过程，并与许多疾病相关。蛋白的聚集在蛋白的泛素酶和去泛素酶的作用目前还很不清楚。我们近期果蝇的工作发现Otu蛋白的“自我聚集”调控其去泛素酶的活性；分子伴侣Bam促进Otu的聚集，进而去除dTRAF6的泛素来调控IMD通路，从而影响果蝇肠道稳态和寿命。我们进一步发现Bam在小鼠的同源物Gm114负调控NF-κB通路活性，本项目在此基础上探讨Gm114调控NF-κB的分子机制，主要将围绕着GM114-A20-TRAF6/2之间的关系进行解析，并利用Gm114 敲除的小鼠研究Gm114在肠道免疫、炎症反应和寿命中的作用。本项目的开展不仅能揭示天然免疫可能的新调控机制，而且可能为今后肠炎诊断或是药物靶点的开发提供重要的理论依据。

Innate immunity is the first line of host defense against invading microorganisms, including bacteria, fungi and viruses. The NF-ĸB signaling pathway has been shown to play evolutionarily conserved roles in regulating innate immunity, inflammation, cell survival, differentiation, and proliferation. However, excessive activities of NF-ĸB signaling may lead to severe consequences including autoimmune and inflammatory diseases. Although NF-ĸB signaling pathway has been extensively studied, how NF-ĸB signaling is precisely controlled in balancing innate immune responses remains to be understood. Our recently published study showed that Drosophila Otu can coalesce to membrane-less granules via its intrinsically disordered low-complexity domain (LC), and that Otu coalescence is critical for its deubiquitinase activity. In gut, the Otu/Bam deubiquitinase complex play important roles in maintaining intestinal immune homeostasis by targeting dTraf6, thereby extending fly lifespan. In this proposal, we plan to investigate whether mammalian homologues of Bam, Gm114 in mouse and Kiz in human, have conserved roles in regulating NF-ĸB signaling. Our preliminary results have shown that both Gm114 and Kiz play negative roles in NF-ĸB activation. Moreover, to elucidate the molecular mechanism of how Gm114 regulates NF-ĸB signaling, we will also study the relationship of Gm114 with deubiquitinase A20 and TRAF2/6. On the basis of our preliminary results indicating that A20 also form aggregation, we will further study the characters and functions of aggregated A20, and test whether Gm114 affects A20 aggregation. Additionally, we will employ Gm114 knockout mice to examine the role of Gm114 in maintaining innate immune homeostasis in intestine，LPS-induced inflammation and lifespan.