Stimulation of the Human Cytomegalovirus IE Enhancer/Promoter in HL-60 Cells by TNFα Is Mediated via Induction of NF-κB

TNFα enhances the basal activity of the major Immediate Early (IE) enhancer/promoter of human cytomegalovirus (HCMV) in the immature premonocytic HL-60 cell line. The stimulatory effect of TNFα is mediated by induction of the transcription factor NF-κB, which specifically binds to the 18-bp repetitive sequence motif of the enhancer region. Complex formation could be competed by oligonucleotides representing the 18-bp sequence motif or the prototype NF-κB sequence of the immunoglobulin κ gene. In gel mobility shift assays antisera specific to NF-κB p50 and p65 subunits were shown to react with the DNA-protein complex. Addition of the antioxidant PDTC blocked TNFα-mediated stimulation in a dose dependent manner. Electrophoretic mobility shift assays indicated that PDTC prevents NF-κB induction. Furthermore, it is suggested that protein kinases like PK-C are involved in the TNFα signal transduction pathway which leads to the activation of NFκB and its binding to the HCMV IE enhancer in HL-60 cells. Our data are consistent with a role of TNFα in reactivation of latent HCMV infection in premonocytic cells.