Selective inhibition of proinflammatory chemokines such as IL-8 is an important approach to combat inflammatory and infection diseases. Previous studies suggested that interaction of transcription factors NFκB repressing factor (NRF) and NFκB play a crucial role in activation of IL-8 gene expression. In a search for a specific inhibitor of IL-8 expression, we applied tandem affinity purification to investigate interaction of NRF and NFκB p65 in cells. We identified a synthetic peptide corresponding to aa 223–238 of NRF interfering with binding of endogenous p65 to NRF. Furthermore, nucleofection experiments were established to introduce this inhibitory peptide into the nucleus of IL-1 stimulated human cervical and Helicobacter pylori infected gastric epithelial cells. Our data clearly show that the specific peptide disturbing NRF/NFκB interaction is able to significantly decrease endogenous IL-8 gene transcription in response to IL-1 or Helicobacter pylori infection. Thus, our study provides novel insights into NRF and NFκB interaction in vivo and may facilitate the design of new anti-IL-8 drugs based on novel strategies.

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Human immunodeficiency virus type 1 (HIV-1) is able to establish a latent infection during which the integrated provirus remains transcriptionally silent. In response to specific stimuli, the HIV-1 long terminal repeat (LTR) is highly activated, enhancing both transcriptional initiation and elongation. Here, we have identified a specific binding sequence of the nuclear NF-B-repressing factor (NRF) within the HIV-1 LTR. The aim of this work was to define the role of NRF in regulating the LTR. Our data show that the endogenous NRF is required for transcriptional activation of the HIV-1 LTR in stimulated cells. In unstimulated cells, however, NRF inhibits HIV-1 LTR activity at the level of transcription elongation. Binding of NRF to the LTR in unstimulated cells prevents recruitment of elongation factor DRB sensitivity-inducing factor and formation of processive elongation complexes by hyperphosphorylated RNA polymerase II. Our data suggest that NRF interrupts the regulatory coupling of LTR binding factors and transcription elongation events. This inhibitory mechanism might contribute to transcriptional quiescence of integrated HIV-1 provirus.

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