Fujikawa K
First Department of Medicine, Hokkaido University School of Medicine, Sapporo, Japan.
Hokkaido Igaku Zasshi. 1992 Jul;67(4):563-74.
NF-IL6 and NF-kappa B are nuclear proteins supposed to play an important role in the regulation of acute-phase protein synthesis and inflammatory response against infection and tissue injury as a host defence mechanism. In addition the promoter region of the interleukin-6 (IL-6) gene has a NF-kappa B binding motif as well as a NF-IL6 binding site. Considering of these facts, we come to investigate that there may be a synergistic effect between NF-IL6 and NF-kappa B in the regulation of IL-6 gene expression. In order to study it, some combinations of expression vectors NF-IL6 cDNA, NF-kappa B (p50/p65) cDNA and reporter plasmid K18-CAT which contains human IL-6 promoter linked to the chloramphenicol acetyltransferase (CAT) gene, were transfected into Jurkat cells and the CAT activities were examined. Co-transfection of NF-IL6 and NF-kappa B (p50/p65) cDNA revealed a dramatic increase of acetylated [14C] chloramphenicol, and its CAT activity reached to 40%. Then, co-transfection of NF-IL6 and NF-kappa B subunit p65 alone showed a high level of CAT activity, too. When 5' deletion mutant reporter plasmid K9-CAT lacking the NF-IL6 binding site was used, co-transfection of NF-IL6 and NF-kappa B (p50/p65) showed low level of CAT activity. These results indicate that there is a synergistic effect between NF-IL6 and NF-kappa B (p50/p65) in IL-6 gene regulation. Among two subunits of NF-kappa B (p50/p65), p65 seems to play an important role rather than p50 does in synergism between NF-IL6 and NF-kappa B. Besides, this synergistic function comes to work only when NF-IL6 binds to its binding site of IL-6 promoter region.
NF-IL6和NF-κB是核蛋白，被认为在急性期蛋白合成调节以及针对感染和组织损伤的炎症反应（作为一种宿主防御机制）中发挥重要作用。此外，白细胞介素-6（IL-6）基因的启动子区域有一个NF-κB结合基序以及一个NF-IL6结合位点。鉴于这些事实，我们着手研究NF-IL6和NF-κB在IL-6基因表达调控中可能存在协同效应。为了对此进行研究，将表达载体NF-IL6 cDNA、NF-κB（p50/p65）cDNA与包含与人IL-6启动子相连的氯霉素乙酰转移酶（CAT）基因的报告质粒K18-CAT的一些组合转染到Jurkat细胞中，并检测CAT活性。NF-IL6和NF-κB（p50/p65）cDNA的共转染显示乙酰化的[14C]氯霉素显著增加，其CAT活性达到40%。然后，单独将NF-IL6和NF-κB亚基p65共转染也显示出高水平的CAT活性。当使用缺乏NF-IL6结合位点的5'缺失突变报告质粒K9-CAT时，NF-IL6和NF-κB（p50/p65）的共转染显示出低水平的CAT活性。这些结果表明NF-IL6和NF-κB（p50/p65）在IL-6基因调控中存在协同效应。在NF-κB（p50/p65）的两个亚基中，p65似乎在NF-IL6和NF-κB的协同作用中比p50发挥更重要的作用。此外，这种协同功能仅在NF-IL6与其在IL-6启动子区域的结合位点结合时才起作用。
