Inhibitor of nuclear factor kappa-B kinase subunit beta (IKKβ) is one of important kinases in inflammation to phosphorylate inhibitor of nuclear factor kappa-B (IκBα) and then activate nuclear factor kappa-B (NF-κB). Inhibition of IKKβ has been a therapeutic strategy for inflammatory and autoimmune diseases. Here we report that IKKβ is constitutively activated in healthy donors and healthy Ikkβ^C46A (cysteine 46 mutated to alanine) knock-in mice although they possess intensive IKKβ–IκBα–NF-κB signaling activation. These indicate that IKKβ activation probably plays homeostatic role instead of causing inflammation. Compared to Ikkβ^WT littermates, lipopolysaccharides (LPS) could induce high mortality rate in Ikkβ^C46A mice which is correlated to breaking the homeostasis by intensively activating p-IκBα–NF-κB signaling and inhibiting phosphorylation of 5ʹ adenosine monophosphate-activated protein kinase (p-AMPK) expression. We then demonstrated that IKKβ kinase domain (KD) phosphorylates AMPKα1 via interacting with residues Thr183, Ser184, and Thr388, while IKKβ helix–loop–helix motifs is essential to phosphorylate IκBα according to the previous reports. Kinase assay further demonstrated that IKKβ simultaneously catalyzes phosphorylation of AMPK and IκBα to mediate homeostasis. Accordingly, activation of AMPK rather than inhibition of IKKβ could substantially rescue LPS-induced mortality in Ikkβ^C46A mice by rebuilding the homeostasis. We conclude that IKKβ activates AMPK to restrict inflammation and IKKβ mediates homeostatic function in inflammation via competitively phosphorylating AMPK and IκBα.

核因子κ-B激酶亚基β（IKKβ ）抑制剂是炎症中重要的激酶之一，可磷酸化核因子κ-B抑制剂（IκBα），然后激活核因子κ-B（NF - κB ） . 抑制 IKK β一直是炎症和自身免疫性疾病的治疗策略。在这里，我们报告 IKK β在健康供体和健康Ikkβ ^C46A（半胱氨酸 46 突变为丙氨酸）敲入小鼠中组成型激活，尽管它们具有密集的 IKK β -I κ B α -NF- κ B 信号传导激活。这些表明 IKKβ激活可能起稳态作用而不是引起炎症。与Ikkβ ^WT同窝小鼠相比，脂多糖 (LPS) 可诱导Ikkβ ^C46A小鼠的高死亡率，这与通过强烈激活 pI κ B α -NF- κ B 信号传导和抑制 5ʹ 腺苷一磷酸活化蛋白激酶的磷酸化来打破稳态相关(p-AMPK) 表达。然后我们证明 IKK β激酶结构域 (KD) 通过与残基 Thr183、Ser184 和 Thr388 相互作用磷酸化 AMPK α 1，而IKK β根据先前的报道，螺旋 - 环 - 螺旋基序对于磷酸化 I κ B α是必不可少的。激酶测定进一步证明 IKK β同时催化 AMPK 和 I κ B α的磷酸化以介导体内平衡。因此，激活 AMPK 而不是抑制 IKK β可以通过重建体内平衡来显着挽救 LPS 诱导的Ikkβ ^C46A小鼠死亡率。我们得出结论，IKK β激活 AMPK 以限制炎症，并且 IKK β通过竞争性磷酸化 AMPK 和IκB介导炎症中的稳态功能α。