Inhibition of Nuclear Translocation of Transcription Factor NF-κB by a Synthetic Peptide Containing a Cell Membrane-permeable Motif and Nuclear Localization Sequence (*)

To control agonist-induced nuclear translocation of transcription factor κB (NF-κB) in intact cells, cell-permeable synthetic peptides were devised. Their import into intact cells was dependent on a hydrophobic region selected from the signal peptide sequences and was verified by their inaccessibility to extracellular proteases and by confocal laser scanning microscopy. When a cell-permeable peptide carried a functional cargo representing the nuclear localization sequence of NF-κB p50, it inhibited in a concentration-dependent manner nuclear translocation of NF-κB in cultured endothelial and monocytic cells stimulated with lipopolysaccharide or tumor necrosis factor-α. Synthetic peptide analogues with deleted hydrophobic cell membrane-permeable motif or with a mutated nuclear localization sequence were inactive. Cell membrane-permeable peptides were not cytotoxic within the concentration range used in these experiments. These results suggest that cell-permeable synthetic peptides carrying a functional cargo can be applied to control signal transduction-dependent subcellular traffic of transcription factors mediating the cellular responses to different agonists. Moreover, this approach can be used to study other intracellular processes involving proteins with functionally distinct domains.