Distinct effects of glutathione disulphide on the nuclear transcription factors κB and the activator protein‐1

Abstract

Oxidative conditions potentiate the activation of the nuclear transcription factor κB (NFκB) and the activator protein‐1 (AP‐1) in intact cells, but inhibit their DNA binding activity in vitro. We now show that both the activation of NFκB and the inhibition of its DNA binding activity is modulated in intact cells by the physiological oxidant glutathione disulphide (GSSG). NFκB activation in human T lineage cells (Molt‐4) by 12‐O‐tetradecanoyl‐phorbol 13‐acetate was inhibited by dithiothreitol, and this was partly reversed by the glutathione reductase inhibitor 1,3‐bis(2‐chloroethyl)‐1‐nitrosourea (BCNU) or by hydrogen peroxide, indicating that GSSG may be required for NFκB activation. These effects of BCNU and hydrogen peroxide were not seen in glutathione‐depleted cells. However, NFκB and AP‐1 activation were potentiated by dithiothreitol if added to cell cultures 1 h after the phorbol ester, indicating that a shift of redox conditions may support optimal oxidative activation with minimal inhibition of DNA binding. The elevation of intracellular GSSG levels by BCNU before stimulation suppressed the chloramphenicol acetyltransferase expression dependent on NFκB but increased that dependent on AP‐1. This selective suppression of NFκB was also demonstrable by electrophoretic mobility shift assays. In vitro, GSSG inhibited the DNA binding activity of NFκB more effectively than that of AP‐1, while AP‐1 was inhibited more effectively by oxidized thioredoxin.