Wissink S, van de Stolpe A, Caldenhoven E, Koenderman L, van der Saag P T
Hubrecht Laboratory, Netherlands Institute for Developmental Biology, Nijmegen, The Netherlands.
Immunobiology. 1997 Dec;198(1-3):50-64. doi: 10.1016/s0171-2985(97)80026-5.
A kappa B-site was identified in the promoter of the intercellular adhesion molecule-1 (ICAM-1) gene, which is involved in regulation of ICAM-1 expression by tumor necrosis factor alpha (TNF-alpha) and glucocorticoids. We now report on the transcription factors which bind and transactivate this enhancer sequence. In vitro, the ICAM-1 kappa B site appeared to bind RelA and c-Rel homodimers as well as heterodimers with NF-kappa B1, but weakly NF-kappa B1 homodimers. In addition, both RelA and c-Rel, but not NF-kappa B1, were shown to transactivate an ICAM-1 kappa B-reporter construct. In monocytic THP-1 cells TNF-alpha induced two nuclear complexes which in vitro bound to the ICAM-1 kappa B site. Using antibodies in an electrophoretic mobility supershift assay, one of these complexes was shown to contain NF-kappa B1 and RelA, and to bind with higher affinity to the consensus kappa B site in the HIV long terminal repeat. The second complex contained RelA, and exhibited higher affinity towards the ICAM-1 kappa B than to the HIV kappa B site. The glucocorticoid receptor was shown to repress activity of both the RelA homodimer and the NF-kappa B1/RelA heterodimer. We argue that in vivo RelA homodimers are likely to play a dominant role in TNF-alpha-induced ICAM-1 transcription in monocytic cells.
在细胞间黏附分子1（ICAM-1）基因的启动子中鉴定出一个κB位点，该基因参与肿瘤坏死因子α（TNF-α）和糖皮质激素对ICAM-1表达的调控。我们现在报告结合并反式激活该增强子序列的转录因子。在体外，ICAM-1κB位点似乎能结合RelA和c-Rel同型二聚体以及与NF-κB1形成的异型二聚体，但与NF-κB1同型二聚体的结合较弱。此外，RelA和c-Rel均能反式激活ICAM-1κB报告基因构建体，而NF-κB1则不能。在单核细胞THP-1细胞中，TNF-α诱导形成两种核复合物，它们在体外能与ICAM-1κB位点结合。在电泳迁移率超迁移试验中使用抗体，其中一种复合物被证明含有NF-κB1和RelA，并且与HIV长末端重复序列中的共有κB位点具有更高的亲和力。第二种复合物含有RelA，对ICAM-1κB的亲和力高于对HIVκB位点的亲和力。糖皮质激素受体被证明能抑制RelA同型二聚体和NF-κB1/RelA异型二聚体的活性。我们认为，在体内RelA同型二聚体可能在单核细胞中TNF-α诱导的ICAM-1转录中起主导作用。
