Regulation of the NF-κB Activation Pathway by Isolated Domains of FIP3/IKKγ, a Component of the IκB-α Kinase Complex*
Regulation of the NF-κB Activation Pathway by Isolated Domains of FIP3/IKKγ, a Component of the IκB-α Kinase Complex*
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DOI：
10.1074/jbc.275.13.9882
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发表时间：
2000-03
期刊：
影响因子：
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通讯作者：
Jianjiang Ye;Xueping Xie;L. Tarassishin;M. Horwitz
中科院分区：
文献类型：
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作者：
Jianjiang Ye;Xueping Xie;L. Tarassishin;M. Horwitz
FIP3 是一种 2 型腺病毒 E3-14.7-kDa 相互作用蛋白，是多聚体 IκB-α 激酶 (IKK) 复合物的重要组成部分，并且已被证明与 NF-κB 激活途径的各种成分（Fas 受体相互作用蛋白、NF-κB 诱导激酶、IKKβ）相互作用。 FIP3 还被证明可以抑制基础和肿瘤坏死因子 (TNF) α 诱导的 NF-κB 活性，并在过度表达时诱导细胞死亡。腺病毒 E3-14.7-kDa 蛋白 (E3-14.7K) 是 TNFα 诱导的细胞死亡的抑制剂。在当前的研究中，我们生成了缺失突变体来绘制 FIP3 的结构域，这些结构域负责其各种功能。 NF-κB 抑制活性和 E3-14.7K 结合域被定位在 FIP3 蛋白的羧基部分。我们还发现 FIP3 的羧基末端部分阻断了 TNFα 诱导的 IκB-α 磷酸化和随后的降解，这表明 NF-κB 细胞质抑制剂的稳定是 FIP3 对 NF-κB 活性抑制的基础。氨基末端 119 个氨基酸负责 FIP3-IKKβ 和 FIP3-IKKα 相互作用，蛋白质的中间（氨基酸 201-300）似乎既是 FIP3 自关联结构域，又是 FIP3-Fas 受体相互作用蛋白相互作用结构域。因此，FIP3 可能作为支架蛋白来组织 IκB-α 激酶复合物的各个组件。虽然有效的细胞死亡需要全长蛋白质，但氨基末端的 200 个氨基酸足以导致细胞变圆和从单层分离。
FIP3, isolated as a type 2 adenovirus E3–14.7-kDa interacting protein, is an essential component of the multimeric IκB-α kinase (IKK) complex and has been shown to interact with various components (Fas receptor-interacting protein, NF-κB-inducing kinase, IKKβ) of the NF-κB activation pathway. FIP3 has also been shown to repress basal and tumor necrosis factor (TNF) α-induced NF-κB activity as well as to induce cell death when overexpressed. The adenovirus E3–14.7-kDa protein (E3-14.7K) is an inhibitor of TNFα-induced cell death. In the current study, we generated deletion mutants to map the domains of FIP3, which are responsible for its various functions. The NF-κB inhibitory activity and the E3–14.7K binding domains were mapped at the carboxyl half of the FIP3 protein. We also found that the carboxyl-terminal half of FIP3 blocked TNFα-induced IκB-α phosphorylation and subsequent degradation, which suggests that the stabilization of the cytoplasmic inhibitor of NF-κB underlies the FIP3 inhibition of NF-κB activity. The amino-terminal 119 amino acids were responsible for the FIP3-IKKβ and FIP3-IKKα interaction, and the middle of the protein (amino acids 201–300) appeared to be both the FIP3 self-association domain as well as the FIP3-Fas receptor-interacting protein interaction domain. Thus, FIP3 might serve as a scaffold protein to organize the various components of the IκB-α kinase complex. Whereas the full-length protein is required for efficient cell death, the amino-terminal 200 amino acids are sufficient to cause rounding and detachment of the cells from the monolayer.