Transcription of proinflammatory cytokine genes is controlled by binding of specific transcription factors in the promoter of target genes. NFκB, a pivotal transcription factor binds in the promoter region of the TNF-α gene and initiates transcription (18). Because we found modulation of NFκB binding activity, we wanted to evaluate whether alcohol affects NFκB promoter-driven transcriptional activity. Transient transfection of the NFκB-driven luciferase reporter in control RAW 264.7 cells or cells exposed to alcohol for 4 days, a time-point showing enhanced NFκB binding in human monocytes, was chosen. Fig. 7B shows that LPS stimulation significantly induced NFκB-mediated luciferase reporter activity. Furthermore, as reported earlier (20), exposure of 25 mM alcohol for up to 24 h or 1 day followed by LPS resulted in a significant reduction of the NFκB-mediated luciferase reporter activity. However, transfection of chronic alcohol-exposed RAW 264.7 cells showed a significant increase in LPS-induced NFκB-mediated luciferase activity (Fig. 7B). These results propose that acute and chronic alcohol exposure modulates NFκB binding activity as well as transactivation suggesting a pivotal role for NFκB in regulating TNF-α expression during alcohol exposure.
