Inducible expression of IκBα repressor mutants interferes with NF-κB activity and HIV-1 replication in Jurkat T cells

Human immunodeficiency virus (HIV-1) utilizes the NF-kappa B/Rel proteins to regulate transcription through NF-kappa B binding sites in the HIV-1 long terminal repeat (LTR). Normally, NF-kappa B is retained in the cytoplasm by inhibitory I kappa.B proteins; after stimulation by multiple activators including viruses, I kappa B alpha is phosphorylated and degraded, resulting in NF-kappa B release. In the present study, we examined the effect of tetracycline inducible expression of transdominant repressors of I kappa B alpha (TD-I kappa B alpha) on HIV-1 multiplication using stably selected Jurkat T cells, TD-I kappa B alpha was inducibly expressed as early as 3 h after doxycycline addition and dramatically reduced both NF-kappa B DNA binding activity and LTR directed gene activity. Interestingly, induced TD-I kappa B alpha expression also decreased endogenous I kappa B alpha expression to undetectable levels by 24 h after induction, demonstrating that TD-I kappa B alpha repressed endogenous NF-kappa B-dependent gene transcription. TD-I kappa B alpha expression also sensitized Jurkat cells to tumor necrosis factor-induced apoptosis. De novo HIV-1 infection of Jurbat cells was dramatically altered by TD-I kappa B alpha induction, resulting in inhibition of HIV-1 multiplication, as measured by p24 antigen, reverse transcriptase, and viral RNA. Given the multiple functions of the NF-kappa B/I kappa B pathway, TD-I kappa B alpha expression may interfere with HIV-1 multiplication at several levels: LTR-mediated transcription, Rev-mediated export of viral RNA, inhibition of HIV-1-induced pro-inflammatory cytokines, and increased sensitivity of HIV-1-infected cells to apoptosis.