RETROVIRUS-MEDIATED TRANSFER OF NUCLEAR FACTOR-KAPPA-B SUBUNIT GENES MODULATES I-KAPPA-B-ALPHA AND INTERFERON-BETA EXPRESSION

Nuclear factor (NF)-kappa B proteins regulate the transcription of num erous genes involved in the immune response, transcription control, an d viral pathogenesis. To examine the effect of ectopic expression of N F-kappa B proteins on DNA-binding activity and gene expression, indivi dual NF-kappa B subunit genes were introduced into NIH 3T3 cells via r etrovirus-mediated gene transfer. Expression of NF-kappa B subunits Re lA (p65), NF-kappa B1 (p105), NF-kappa B2 (p100), and c-Rel increased the basal level of nuclear NF-kappa B DNA binding in NIH 3T3 cells, wh ereas expression of Delta RelA (p65 Delta) and NF-kappa B2 (p52) subun its did not affect basal level activity. Tumor necrosis factor-alpha t reatment of the NF-kappa B-expressing cells stimulated the induced lev el of DNA-binding activity, reflecting interaction between endogenous murine and transfected human NF-kappa B proteins. Interestingly, expre ssion of ReIA (p65), c-Rel, NF-kappa B1 (p105), NF-kappa B2 (p100), an d NF-kappa B2 (p52) subunits increased I kappa B alpha protein levels from 3- to 30-fold, indicating that one mechanism to compensate for th e increased expression of NF-kappa B proto-oncogenes was to increase t he synthesis and/or stability of the regulatory I kappa B alpha protei n. In addition, overexpression of RelA (p65), c-Rel, NF-kappa B2 (p100 ), and NF-kappa B2 (p52) altered the induction kinetics of IFN-beta mR NA after Senhai virus infection, whereas overexpression of NF-kappa B1 (p105) dramatically decreased IFN-beta mRMA induction.