PDF(Pubmed)
Abstract：
The NLRP3 inflammasome, a pivotal component of innate immunity, has been implicated in various inflammatory disorders. The ubiquitin-editing enzyme A20 is well known to regulate inflammation and maintain homeostasis. However, the precise molecular mechanisms by which A20 modulates the NLRP3 inflammasome remain poorly understood. Here, our study revealed that macrophages deficient in A20 exhibit increased protein abundance and elevated mRNA level of NIMA-related kinase 7 (NEK7). Importantly, A20 directly binds with NEK7, mediating its K48-linked ubiquitination, thereby targeting NEK7 for proteasomal degradation. Our results demonstrate that A20 enhances the ubiquitination of NEK7 at K189 and K293 ubiquitinated sites, with K189 playing a crucial role in the binding of NEK7 to A20, albeit not significantly influencing the interaction between NEK7 and NLRP3. Furthermore, A20 disrupts the association of NEK7 with the NLRP3 complex, potentially through the OTU domain and/or synergistic effect of ZnF4 and ZnF7 motifs. Significantly, NEK7 deletion markedly attenuates the activation of the NLRP3 inflammasome in A20-deficient conditions, both in vitro and in vivo. This study uncovers a mechanism by which A20 inhibits the NLRP3 inflammasome.
摘要：
NLRP3炎性体,先天免疫的关键组成部分，与各种炎症性疾病有关。众所周知，泛素编辑酶A20可以调节炎症并维持稳态。然而,A20调节NLRP3炎性体的确切分子机制仍然知之甚少。这里,我们的研究显示,缺乏A20的巨噬细胞表现出蛋白丰度增加和NIMA相关激酶7(NEK7)mRNA水平升高.重要的是,A20直接与NEK7结合，介导其K48连接的泛素化，从而靶向NEK7用于蛋白酶体降解。我们的结果表明，A20增强了NEK7在K189和K293泛素化位点的泛素化，K189在NEK7与A20的结合中起关键作用，尽管没有显着影响NEK7与NLRP3之间的相互作用。此外，A20破坏了NEK7与NLRP3复合体的联系，可能通过OTU结构域和/或ZnF4和ZnF7基序的协同作用。重要的是,在A20缺陷条件下，NEK7缺失显著减弱NLRP3炎性体的激活，在体外和体内。本研究揭示了A20抑制NLRP3炎性体的机制。
