Optimal NFκB Mediated Transcriptional Responses in Jurkat T Cells Exposed to Oxidative Stress Are Dependent on Intracellular Glutathione and Costimulatory Signals

Abstract

Many early response genes induced by the exposure of mammalian cells to environmental stress contain DNA sequences which bind nuclear factor (NF) κB. However, the effects of oxidative stress on NFκB activity in T cells are contradictory with evidence supporting both stimulation and suppression. The present investigation examined the effects of low levels of oxidative stress in the form of H2O2on NFκB transactivation in Jurkat T cells and the regulation of NFκB activity by cellular glutathione (GSH) levels and costimulatory signals. Transient transfection analyses demonstrated 2-3 fold increases in transcription of an NFκB dependent chloramphenicol acetyl transferase (CAT) reporter after the exposure of Jurkat cells to 100-500 μM H2O2. By comparison, dual stimulation of Jurkat cells with phytohemagglutinin (PHA) plus phorbol (PMA) induced 9-10 fold increases in NFκB CAT activity. Although no marked changes in GSH levels were detected in cells treated with H2O2or PHA/PMA, the depletion of GSH in cells pretreated withDL-buthionine-[S,R]-sulfoximine (BSO) substantially inhibited NFκB transactivation by H2O2. In addition, H2O2was less effective than PHA/PMA in inducing NFκB1 (p50)/RelA (p65) complexes. However, signals induced by oxidative conditions effectively cooperated with stimulatory signals provided by PMA but not with T cell receptor/CD3 stimulation to induce significant increases in NFκB CAT responses. These results suggest that a functional GSH system is required for NFκB activation in T cells exposed to oxidative reagents and provide evidence that oxidative stress triggers signaling events capable of participating with distinct coregulatory signals to activate NFκB transcriptional responses.