NF‐IL6 is a nuclear factor that specifically binds to an IL1‐responsive element in the IL‐6 gene. In this study the gene encoding NF‐IL6 has been cloned by direct screening of a lambda gt11 library using NF‐IL6 binding sequence as a ligand. The full‐length cDNA encoded a 345 amino acid protein with a potential leucine zipper structure and revealed a high degree of homology to a liver‐specific transcriptional factor, C/EBP, at the C‐terminal portion. The bacterial fusion protein bound to the CCAAT homology as well as the viral enhancer core sequences as in the case of C/EBP. Recombinant NF‐IL6 activated the human IL‐6 promoter in a sequence‐specific manner. Southern blot analysis demonstrated the high‐degree conservation of the NF‐IL6 gene through evolution and the existence of several other related genes sharing the DNA‐binding domain. NF‐IL6 mRNA was normally not expressed, but induced by the stimulation with either LPS, IL‐1 or IL‐6. Interestingly, NF‐IL6 was shown to bind to the regulatory regions for various acute‐phase protein genes and several other cytokine genes such as TNF, IL‐8 and G‐CSF, implying that NF‐IL6 has a role in regulation not only for the IL‐6 gene but also for several other genes involved in acute‐phase reaction, inflammation and hemopoiesis.

Single binding sites for transcription factors NF-IL6 and NF-iB are present in the promoter of the interleukin (IL) 6 gene. Previous studies of internally deleted promoter mutants demonstrated that these two sites are important for the transcriptional regulation of this gene. In this report, we describe the synergistic activation of the IL-6 promoter by transcription factors NF-IL6 and NF-KB. Cotransfection of NF-IL6 with the NF-cB p65 subunit resulted in strong synergistic activation of an IL-6 promoter-reporter construct. Both the NF-IL6 and NF-cB binding sites in the IL-6 promoter were required for synergistic activation. Similar synergistic activation was observed in the IL-8 promoter, which also contains both NF-IL6 and NF-cB binding sites. Furthermore, we demonstrated that NF-IL6 and the NF-KB p65 subunit directly associated via the basic leucine-zipper domain of NF-IL6 and the Rel homology domain of p65. Since the promoters of many other genes involved in the inflammatory and acute-phase responses also contain binding sites for NF-IL6 and NF-cB, the cooperation between these two factors may have an important role in these responses. We also discuss the possible interplay between various viral gene products and these two factors in the process of viral infection and constitutive cytokine production.

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Although estrogen is known to activate endothelial nitric oxide synthase (eNOS) in the vascular endothelium, the molecular mechanism responsible for this effect remains to be elucidated. In studies of both human umbilical vein endothelial cells ( The inhibitory effect of estrogen on the development of atherosclerosis has been suggested by abundant human epidemiological and animal experimental data (1-9). The incidence of atherosclerotic diseases is lower in premenopausal women than in men, steeply rises in postmenopausal women, and is reduced to premenopausal levels in postmenopausal women who receive estrogen therapy (10 -12). Until recently, the atheroprotective effects of estrogen were attributed principally to the effects on serum lipid concentrations. However, estrogeninduced alterations in serum lipids account for only approximately one-third of the observed clinical benefits of estrogen (12)(13)(14). Recent evidence suggests that the direct actions of estrogen on blood vessels contribute to the cardioprotective effects of estrogen (13, 15). There are many kinds of direct effects of estrogen on blood vessels, such as estrogen-induced increases of vasodilatation and inhibition of the response of blood vessels to injury and the development of atherosclerosis. However, the molecular mechanism underlying the estrogeninduced vasodilatation has not yet been determined. Several studies suggest that a key mediator of this vasodilator response could be the endothelium-derived relaxing factor nitric oxide (NO), and that brief treatment with estrogen increases basal NO release in endothelial cells without elevation of eNOS mRNA or protein (16). Estrogen activates endothelial nitric oxide synthase (eNOS) without altering expression of the eNOS gene in vascular endothelium (17)(18)(19)(20). However, the details of the mechanism of the estrogen-induced eNOS activation are not yet well understood.The serine/threonine kinase termed Akt or protein kinase B (PKB) 1 is an important regulator of various cellular processes, including glucose metabolism and cell survival (21, 22). Activation of receptor tyrosine kinases and G-protein-coupled receptors, and stimulation of cells by mechanical force, can lead to the phosphorylation and activation of . Akt was identified as a downstream component of survival signaling through phosphatidylinositol 3-kinase (PI3K) (26 -30). Akt may be regulated by both phosphorylation and the direct binding of PI3K lipid products to the Akt pleckstrin homology domain. Akt can then phosphorylate substrates such as glycogen synthase kinase-3, 6-phosphofructo-2-kinase, and BAD. More recently, it was found that eNOS is also an Akt substrate and is activated by Akt-dependent phosphorylation to release NO in endothelial cells (31-34).The actions of estrogen can be mediated by the classical nuclear receptors, ER␣ and ER␤ (35,36) or through other putative membrane receptors. By definition, rapid effects of estrogen that involve nongenomic mechanisms are independent of transcriptional activation by the nuclea...

We investigated whether inhibition of nuclear factor-B (NF B) increases the efficacy of paclitaxel in in vitro