The Activity Of NF-KB In Swiss 3T3 Cells Exposed To Aqueous Extracts Of Cigarette Smoke Is Dependent On Thioredoxin

Studies on stress signal transduction in swiss 3T3 cells exposed to aqueous extracts of CS (‘smoke-bubbled PBS’) revealed the activation of mitogen activated protein kinases (mapks), i.e., stress-activated protein kinase (SAPK) and p38, as well as the modulation of transcription factors AP-1 and NF-kappa B as detected by electromobility shift assay techniques. Unlike complexes, that bind to AP-1 sites, NF-kappa B DNA binding was strikingly decreased during the first 2 h of exposure followed by a more than 2- fold increase over controls after 4 to 6 h of exposure. This type of kinetics is not subject to regulation by i kappa b-alpha has evidenced by the lack of phosphorylation and degradation of i kappa b-alpha in CS-treated cells.However, as demonstrated by immuno-co-precipitation experiments, the kinetics of NF-kappa B DNA-binding was strictly paralleled by decreased and increased complex formation between NF-kappa B and thioredoxin (TRX), the reducing catalyst of cys-62 of NF-kappa B, which is required for efficient DNA binding. These results suggest that the activity of NF-kappa B in smoke-bubbled PBS-treated cells is subject mainly to a redoxcontrolled mechanism dependent on the availability of reduced TRX rather than being controlled by its normal regulator I Kappa B-Alpha.