Abstract：
Mounting evidence indicates that proteotoxic stress is a primary activator of the CARD8 inflammasome, but the complete array of signals that control this inflammasome have not yet been established. Notably, we recently discovered that several hydrophobic radical-trapping antioxidants (RTAs), including JSH-23, potentiate CARD8 inflammasome activation through an unknown mechanism. Here, we report that these RTAs directly alkylate several cysteine residues in the N-terminal disordered region of CARD8. These hydrophobic modifications destabilize the repressive CARD8 N-terminal fragment and accelerate its proteasome-mediated degradation, thereby releasing the inflammatory CARD8 C-terminal fragment from autoinhibition. Consistently, we also found that unrelated (non-RTA) hydrophobic electrophiles as well as genetic mutation of the CARD8 cysteine residues to isoleucines similarly potentiate inflammasome activation. Overall, our results not only provide further evidence that protein folding stress is a key CARD8 inflammasome-activating signal, but also indicate that the N-terminal cysteines can play key roles in tuning the response to this stress.
摘要：
越来越多的证据表明，蛋白毒性应激是CARD8炎性体的主要激活剂，但是控制这个炎症小体的完整信号还没有建立起来。值得注意的是,我们最近发现了几种疏水性自由基捕获抗氧化剂（RTAs），包括JSH-23，通过未知机制增强CARD8炎性体激活。这里,我们报告说，这些RTA直接烷基化了CARD8N端无序区域中的几个半胱氨酸残基。这些疏水修饰使抑制性CARD8N末端片段不稳定，并加速其蛋白酶体介导的降解，从而从自身抑制中释放炎性CARD8C末端片段。始终如一，我们还发现,不相关的(非RTA)疏水性亲电试剂以及CARD8半胱氨酸残基向异亮氨酸的基因突变类似地增强了炎性小体的激活.总的来说,我们的研究结果不仅提供了进一步的证据，表明蛋白质折叠应激是一个关键的CARD8炎性体激活信号，但也表明N端半胱氨酸可以在调节对这种应激的反应中发挥关键作用。
