Abstract：
IkappaB kinase beta (IKKβ) is a key member of IκB kinases and functions importantly in interferon (IFN) signaling. Phosphorylation and ubiquitination are involved in the activation of IKKβ. A20 is a de-ubiquitin enzyme and functions as a suppressor in inflammation signaling, which has been reported to be phosphorylated and activated by IKKβ. However, the role and relationship of IKKβ and A20 in teleost remains unclear. In this study, IKKβ (bcIKKβ) and A20 (bcA20) of black carp (Mylopharyngodon piceus) have been cloned and characterized. Overexpressed bcIKKβ in EPC cells showed strong anti-viral ability by activating both NF-κB and IFN signaling. EPC cells stable expressing bcIKKβ presented improved anti-viral activity as well. The interaction between bcA20 and bcIKKβ was identified, and overexpression of bcA20 was able to suppress bcIKKβ-mediated activation of NF-κB and IFN signaling. Meanwhile, knock-down of A20 increased host the antiviral ability of host cells. Importantly, it has been identified that bcA20 was able to remove K27-linked ubiquitination and decrease the phosphorylation of bcIKKβ. Thus, our data conclude that bcA20 suppresses the anti-viral activity of bcIKKβ and removes its K27-linked ubiquitination, which presents a new mechanism of IKKβ regulation.
摘要：
IkappaB激酶β（IKKβ）是IκB激酶的关键成员，在干扰素（IFN）信号传导中起重要作用。磷酸化和泛素化参与IKKβ的活化。A20是一种去泛素酶，在炎症信号传导中起抑制作用，据报道被IKKβ磷酸化和激活。然而,IKKβ和A20在硬骨鱼中的作用和关系尚不清楚。在这项研究中,已克隆并鉴定了黑鲤鱼（Mylophingodonpiceus）的IKKβ（bcIKKβ）和A20（bcA20）。EPC细胞中过表达的bcIKKβ通过激活NF-κB和IFN信号传导显示出强的抗病毒能力。稳定表达bcIKKβ的EPC细胞也呈现改善的抗病毒活性。确定了bcA20和bcIKKβ之间的相互作用，bcA20的过表达能够抑制bcIKKβ介导的NF-κB和IFN信号的激活。同时,A20的敲低增加宿主细胞的抗病毒能力。重要的是,已经确定bcA20能够去除K27连接的泛素化并降低bcIKKβ的磷酸化。因此，我们的数据得出结论，bcA20抑制bcIKKβ的抗病毒活性，并消除其K27连接的泛素化，提出了一种新的IKKβ调控机制。
