Institute for Genetics, Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD) and Center for Molecular Medicine, University of Cologne, Cologne, Germany.
VIB Center for Inflammation Research, Ghent, Belgium.
Nat Cell Biol. 2019 Jun;21(6):731-742. doi: 10.1038/s41556-019-0324-3. Epub 2019 May 13.
Deficiency in the deubiquitinating enzyme A20 causes severe inflammation in mice, and impaired A20 function is associated with human inflammatory diseases. A20 has been implicated in negatively regulating NF-κB signalling, cell death and inflammasome activation; however, the mechanisms by which A20 inhibits inflammation in vivo remain poorly understood. Genetic studies in mice revealed that its deubiquitinase activity is not essential for A20 anti-inflammatory function. Here we show that A20 prevents inflammasome-dependent arthritis by inhibiting macrophage necroptosis and that this function depends on its zinc finger 7 (ZnF7). We provide genetic evidence that RIPK1 kinase-dependent, RIPK3-MLKL-mediated necroptosis drives inflammasome activation in A20-deficient macrophages and causes inflammatory arthritis in mice. Single-cell imaging revealed that RIPK3-dependent death caused inflammasome-dependent IL-1β release from lipopolysaccharide-stimulated A20-deficient macrophages. Importantly, mutation of the A20 ZnF7 ubiquitin binding domain caused arthritis in mice, arguing that ZnF7-dependent inhibition of necroptosis is critical for A20 anti-inflammatory function in vivo.
缺乏去泛素化酶 A20 会导致小鼠严重炎症，而 A20 功能受损与人类炎症性疾病有关。A20 被认为可负调控 NF-κB 信号转导、细胞死亡和炎性小体激活；然而，A20 体内抑制炎症的机制仍知之甚少。在小鼠中的遗传研究表明，其去泛素酶活性对于 A20 的抗炎功能并非必需。在这里，我们表明 A20 通过抑制巨噬细胞坏死性凋亡来预防炎性小体依赖性关节炎，而这一功能依赖于其锌指结构域 7（ZnF7）。我们提供了遗传证据表明，RIPK1 激酶依赖性、RIPK3-MLKL 介导的坏死性凋亡驱动 A20 缺陷型巨噬细胞中的炎性小体激活，并导致小鼠炎症性关节炎。单细胞成像显示，RIPK3 依赖性死亡导致脂多糖刺激的 A20 缺陷型巨噬细胞中炎性小体依赖性 IL-1β 的释放。重要的是，A20 ZnF7 泛素结合结构域的突变会导致小鼠关节炎，这表明 ZnF7 依赖性抑制坏死性凋亡对于 A20 在体内的抗炎功能至关重要。
