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The transcription factor NF-κB regulates many genes involved in proinflammatory and immune responses. The transport of NF-κB into the nucleus is essential for its biologic activity. We describe a novel, potent, and selective NF-κB inhibitor composed of a cell-permeable peptide carrying two nuclear localization sequences (NLS). This peptide blocks NF-κB nuclear localization, resulting in inhibition of cell surface protein expression, cytokine production, and T cell proliferation. The peptide is efficacious in vivo in a mouse septic shock model as well as a mouse model of inflammatory bowel disease, demonstrating that NF-κB nuclear import plays a role in these acute inflammatory disease models.

The 70 kDa heat shock protein (Hsp70) is a highly conserved, ubiquitous protein involved in chaperoning proteins to various cellular organelles. Here we show that when added exogenously to cells, Hsp70 is readily imported into both cytoplasmic and nuclear compartments in a cell-type-specific fashion. We exploited this ability of Hsp70 to deliver NF-κB, a key transcriptional regulator of inflammatory responses. We demonstrate that a fusion protein composed of a C-terminal Hsp70 peptide and the p50 subunit of NF-κB was directed into the nucleus of cells, could bind DNA specifically, and activated Igκ expression and TNFα production. We therefore propose that Hsp70 can be used as a vehicle for intracytoplasmic and intranuclear delivery of proteins or DNA to modulate gene expression and thereby control immune responses.

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