The NF-kappa b repressing factor is involved in basal repression and interleukin (IL)-1-induced activation of IL-8 transcription by binding to a conserved NF-kappa b-flanking sequence element.
Interleukin (IL)-8, a prototypic chemokine, is rapidly induced by the pro-inflammatory cytokine IL-1 but is barely detectable in noninduced cells. Although there is clear evidence that the transcription factor NF-kappaB plays a central role in inducible IL-8 transcription, very little is known about the cis-elements and trans-acting factors involved in silencing of the IL-8 promoter. By sequence comparison with the interferon-beta promoter, we found a negative regulatory element (NRE) in the IL-8 promoter overlapping partially with the NF-kappaB response element. Here we show that an NF-kappaB-repressing factor (NRF) binds to the IL-8 promoter NF-kappaB-NRE. Reduction of cellular NRF by expressing NRF antisense RNA results in spontaneous IL-8 gene expression. In contrast, IL-1-induced IL-8 secretion is strongly impaired by expressing NRF antisense RNA. Mutation of the NRE site results in loss of NRF binding and increased basal IL-8 transcription. On the other hand IL-1-induced IL-8 transcription is decreased by mutating the NRE. These data provide evidence for a dual role of the NRF in IL-8 transcription. Although in the absence of stimulation it is involved in transcriptional silencing, in IL-1-induced cells it is required for full induction of the IL-8 promoter.
Nourbakhsh
M
M
Department of Gene Regulation and Differentiation, GBF-National Research Institute for Biotechnology, Mascheroder Weg 1, D-38124 Braunschweig, Germany.
Kalble
S
S
Dorrie
A
A
Hauser
H
H
Resch
K
K
Kracht
M
M
D001483:Base Sequence; D004247:DNA; D004268:DNA-Binding Proteins; D006367:HeLa Cells; D006801:Humans; D007375:Interleukin-1 / Q000502:physiology*; D016209:Interleukin-8 / Q000235:genetics*; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011485:Protein Binding; D012097:Repressor Proteins / Q000378:metabolism / Q000502:physiology*; D012689:Sequence Homology, Nucleic Acid; D014157:Transcription Factors / Q000378:metabolism / Q000502:physiology*; D015533:Transcriptional Activation
D004268:DNA-Binding Proteins; D007375:Interleukin-1; D016209:Interleukin-8; D016328:NF-kappa B; C111027:NKRF protein, human; D012097:Repressor Proteins; D014157:Transcription Factors; D004247:DNA; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases