Inflammatory osteolysis is regulated by site-specific ISGylation of the scaffold protein NEMO
Inflammatory osteolysis is regulated by site-specific ISGylation of the scaffold protein NEMO
复制标题
DOI：
10.7554/elife.56095
复制
发表时间：
2020-03-23
期刊：
影响因子：
7.7
通讯作者：
Abu-Amer, Yousef
中科院分区：
文献类型：
--
作者：
Adapala, Naga Suresh;Swarnkar, Gaurav;Abu-Amer, Yousef
炎性骨溶解是由加剧的破骨细胞生成引起的。大量证据表明，核因子-kappaB在这种病理反应中起中心作用，但支持这些反应特异性的确切机制仍不清楚。我们认为支架蛋白IKK伽马/NEMO的基序在一定程度上促进了这种功能。作为原理的证据，我们使用定点突变来检测NEMO在介导RANKL诱导的小鼠骨髓巨噬细胞中的信号传递中的作用，该信号被称为破骨细胞前体。我们发现赖氨酸(K)270是调节RANKL信号的靶点，因为K270A的替代在体外会导致旺盛的破骨细胞生成，在体内会导致小鼠炎性骨溶解。从机制上讲，我们发现K270A突变破坏了自噬，稳定了NEMO，并增加了炎症负担。具体地说，K270A直接或间接地阻止Nemo与ISG15的结合，ISG15是一种泛素样蛋白，我们发现ISG15针对的是自噬介导的溶酶体降解的修饰蛋白。综上所述，我们的发现表明，NEMO可以作为一个工具包，在生理和病理条件下微调特定的信号。
Inflammatory osteolysis is governed by exacerbated osteoclastogenesis. Ample evidence points to central role of NF-kappa B in such pathologic responses, yet the precise mechanisms underpinning specificity of these responses remain unclear. We propose that motifs of the scaffold protein IKK gamma/NEMO partly facilitate such functions. As proof-of-principle, we used site-specific mutagenesis to examine the role of NEMO in mediating RANKL-induced signaling in mouse bone marrow macrophages, known as osteoclast precursors. We identified lysine (K)270 as a target regulating RANKL signaling as K270A substitution results in exuberant osteoclastogenesis in vitro and murine inflammatory osteolysis in vivo. Mechanistically, we discovered that K270A mutation disrupts autophagy, stabilizes NEMO, and elevates inflammatory burden. Specifically, K270A directly or indirectly hinders binding of NEMO to ISG15, a ubiquitin-like protein, which we show targets the modified proteins to autophagy-mediated lysosomal degradation. Taken together, our findings suggest that NEMO serves as a toolkit to fine-tune specific signals in physiologic and pathologic conditions.