Pre-exposure to oxidative stress decreases the nuclear factor-kappa B-dependent transcription in T lymphocytes.
Reactive oxygen species (ROS) are used as signaling molecules in T cell activation. One of the main targets of ROS is the transcription factor nuclear factor-kappa B (NF-kappa B). NF-kappa B-dependent transcription is inhibited by antioxidants, and the activation is induced or potentiated by ROS. However, chronic oxidative stress is known to reduce the activation of T cells and NF-kappa B. To analyze these phenomena in more detail, we have exposed Jurkat T cells in vitro to oxidative stress (H2O2) at various times before or simultaneously with signals known to activate NF-kappa B (phorbol dibutyrate (PDBu) and TNF). Simultaneously applied H2O2 strongly potentiated the PDBu- or TNF-induced transcriptional activity of NF-kappa B. In contrast to this, H2O2 given 3 to 20 h before the activating signal reduced NF-kappa B-dependent transcriptional activity. This was not due to the oxidation-induced modification of NF-kappa B; cytoplasmic NF-kappa B was able to bind to DNA after dissociation from I kappa B alpha by detergent treatment. H2O2 pre-exposure effectively inhibited the PDBu- or TNF-induced phosphorylation and degradation of I kappa B alpha, but H2O2 given simultaneously with PDBu or TNF enhanced the degradation. Oxidative stress was also followed by a strongly decreased ability to form intracellular ROS. Taken together, these data indicate that I kappa B alpha phosphorylation is the target of action of ROS, and as the ROS-forming capacity is weaker after chronic oxidative stress, I kappa B alpha is not effectively phosphorylated and degraded, thus leading to decreased NF-kappa B-dependent transcription.
Lahdenpohja
N
N
Department of Microbiology and Immunology, University of Tampere Medical School, Finland. llnila@uta.fi.
Savinainen
K
K
Hurme
M
M
D004268:DNA-Binding Proteins / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D020672:I-kappa B Proteins; D007424:Intracellular Fluid / Q000378:metabolism; D019169:Jurkat Cells; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000235:genetics*; D018384:Oxidative Stress / Q000276:immunology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D013601:T-Lymphocytes / Q000187:drug effects / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects / Q000276:immunology*
D004268:DNA-Binding Proteins; D020672:I-kappa B Proteins; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D017382:Reactive Oxygen Species; D000072000:NF-KappaB Inhibitor alpha; D006861:Hydrogen Peroxide