A selective IKK-2 inhibitor blocks NF-κB-dependent gene expression in interleukin-1β-stimulated synovial fibroblasts
A selective IKK-2 inhibitor blocks NF-κB-dependent gene expression in interleukin-1β-stimulated synovial fibroblasts
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DOI：
10.1074/jbc.m211439200
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发表时间：
2003-08-29
影响因子：
4.8
通讯作者：
Tripp, CS
中科院分区：
文献类型：
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作者：
Kishore, N;Sommers, C;Tripp, CS
NF-κ B诱导的基因表达在炎症性疾病如关节炎的发病机制中起重要作用。IkappaB激酶（IKK）是通过广谱炎性激动剂激活NF-κ B的汇聚点，因此是治疗干预的新靶点。我们描述了一种IKK-2的小分子选择性抑制剂SC-514，它不抑制其他IKK亚型或其他丝氨酸-苏氨酸和酪氨酸激酶。SC-514对天然IKK复合物或重组人IKK-1/IKK-2异源二聚体和IKK-2同源二聚体的抑制作用相似。SC-514对IKK-2的抑制是选择性的、可逆的，并且与ATP竞争。SC-514以剂量依赖性方式抑制IL-1 β诱导的类风湿性关节炎滑膜成纤维细胞中NF-κ B依赖性基因的转录。当在存在这种抑制剂的情况下评估NF-κ B活化的机制时，发现了几个有趣的观察结果：首先，SC-514不抑制IKK复合物的磷酸化和活化。第二，IkappaB α磷酸化和降解有延迟，但不是完全阻断;同样，p65进入细胞核的速度略有减慢，减少，而p65从细胞核的输出速度加快。最后，IkappaB α和p65都是IKK-2的相当底物，具有相似的K-m和K-cat值，SC-514相似地抑制任一底物的磷酸化。因此，SC-514对细胞因子基因表达的影响可能是抑制IkappaB α磷酸化/降解、影响NF-κ B核输入/输出以及p65磷酸化和反式激活的组合。
NF-kappaB-induced gene expression contributes significantly to the pathogenesis of inflammatory diseases such as arthritis. IkappaB kinase (IKK) is the converging point for the activation of NF-kappaB by a broad spectrum of inflammatory agonists and is thus a novel target for therapeutic intervention. We describe a small molecule, selective inhibitor of IKK-2, SC-514, which does not inhibit other IKK isoforms or other serine-threonine and tyrosine kinases. SC-514 inhibits the native IKK complex or recombinant human IKK-1/IKK-2 heterodimer and IKK-2 homodimer similarly. IKK-2 inhibition by SC-514 is selective, reversible, and competitive with ATP. SC-514 inhibits transcription of NF-kappaB-dependent genes in IL-1beta-induced rheumatoid arthritis-derived synovial fibroblasts in a dose-dependent manner. When the mechanism of NF-kappaB activation was evaluated in the presence of this inhibitor, several interesting observations were found. First, SC-514 did not inhibit the phosphorylation and activation of the IKK complex. Second, there was a delay but not a complete blockade in IkappaBalpha phosphorylation and degradation; likewise there was a slightly slowed, decreased import of p65 into the nucleus and a faster export of p65 from the nucleus. Finally, both IkappaBalpha and p65 were comparable substrates for IKK-2, with similar K-m and K-cat values, and SC-514 inhibited the phosphorylation of either substrate similarly. Thus, the effect of SC-514 on cytokine gene expression may be a combination of inhibiting IkappaBalpha phosphorylation/ degradation, affecting NF-kappaB nuclear import/ export as well as the phosphorylation and transactivation of p65.