Jobin C, Morteau O, Han D S, Balfour Sartor R
Departments of Medicine, Microbiology, Immunology and the Center for Gastrointestinal Biology and Disease, University of North Carolina, Chapel Hill, NC 27599, USA.
Immunology. 1998 Dec;95(4):537-43. doi: 10.1046/j.1365-2567.1998.00646.x.
Cyclo-oxygenase (COX) is the key regulatory enzyme of the prostaglandin/eicosanoid pathway. While COX-1 is mostly constitutively expressed, the COX-2 isoform is inducible by proinflammatory cytokines. We used an adenoviral vector containing an NF-kappaB super-repressor (Ad5IkappaB) to investigate the role of NF-kappaB in tumour necrosis factor-alpha (TNF-alpha)-mediated COX-2 gene expression in a colonic epithelial cell line. COX-1 mRNA and protein were constitutively expressed in uninfected, control Ad5LacZ- or Ad5IkappaB-infected HT-29 cells with no apparent change following TNF-alpha exposure. COX-2 mRNA and protein expression was undetectable in unstimulated cells but was strongly up-regulated after TNF-alpha stimulation in uninfected and Ad5LacZ-infected HT-29 cells. This induction was prevented in Ad5IkappaB cells. TNF-alpha increased prostaglandin E2 production by 20-fold in Ad5LacZ-infected HT-29 cells compared with uninfected cells and was significantly inhibited in Ad5IkappaB-infected cells in agreement with the COX-2 mRNA findings. We conclude that NF-kappaB activation is critical in mediating COX-2, but not COX-1 gene expression in HT-29 cells. Selective inhibition of COX-2 expression with the NF-kappaB super-repressor may be useful in distinguishing the role of inducible versus constitutive prostaglandins in intestinal function and provides greater specificity than pharmacological inhibitors.
环氧化酶（COX）是前列腺素/类花生酸途径的关键调节酶。虽然COX-1大多为组成性表达，但COX-2同工型可被促炎细胞因子诱导。我们使用了一种含有NF-κB超级抑制剂（Ad5IkappaB）的腺病毒载体，来研究NF-κB在结肠上皮细胞系中肿瘤坏死因子-α（TNF-α）介导的COX-2基因表达中的作用。COX-1 mRNA和蛋白在未感染、对照Ad5LacZ或Ad5IkappaB感染的HT-29细胞中组成性表达，TNF-α暴露后无明显变化。COX-2 mRNA和蛋白表达在未刺激的细胞中无法检测到，但在未感染和Ad5LacZ感染的HT-29细胞中，TNF-α刺激后强烈上调。这种诱导在Ad5IkappaB细胞中被阻止。与未感染细胞相比，TNF-α使Ad5LacZ感染的HT-29细胞中前列腺素E2的产生增加了20倍，并且与COX-2 mRNA的结果一致，在Ad5IkappaB感染的细胞中被显著抑制。我们得出结论，NF-κB激活在介导HT-29细胞中COX-2而非COX-1基因表达方面至关重要。用NF-κB超级抑制剂选择性抑制COX-2表达，可能有助于区分诱导型与组成型前列腺素在肠道功能中的作用，并且比药理抑制剂具有更高的特异性。
