AP-1 DNA-binding activity is inhibited by selenite and selenodiglutathione

The binding of the transcription factor AP-1 to DNA has been shown to be modulated by redox control mechanisms. Selenite and selenodiglutathione (GS-Se-SG), inhibit mammalian cell growth and are efficient oxidants of reduced thioredoxin and reduced thioredoxin reductase. Here, we report that selenite and GS-Se-SG efficiently inhibited AP-1 DNA-binding in nuclear extracts from 3B6 lymphocytes. A GS-Se-SG concentration of 0.75 microM resulted in 50% inhibition of AP-1 DNA-binding, whereas the same effect was achieved with 7.5 microM selenite. Nuclear extracts prepared from human 3B6 lymphocytes exposed for 4 h to 10 microM selenite showed a 50% reduction of AP-1 binding. These data suggest that selenite and selenodiglutathione inactivate the AP-1 factor and provide a mechanism by which selenium compounds inhibit cell growth.