Activation of the transcription factor NF-kappaB in lipopolysaccharide-stimulated U937 cells.
During the course of serious bacterial infections, lipopolysaccharide (LPS) interacts with monocyte/macrophage receptors, resulting in the generation of inflammatory cytokines. Transcription factor NF-kappaB is crucial in activating the transcription of genes encoding proinflammatory cytokines. In this paper, we demonstrate that the activation of NF-kappaB by LPS in a promonocytic cell line (U937) followed a rather slow kinetics, depending on the rate of IkappaB-alpha inhibitor hydrolysis. No degradation of p105 and p100 inhibitors was observed under these conditions. The transduction pathway leading to NF-kappaB activation in U937 cells involved the intracellular generation of reactive oxygen species (ROS), as demonstrated by the concomitant inhibitory effects of antioxidants on NF-kappaB activation and the emission of a fluorescent probe reacting intracellularly with hydrogen peroxide. This ROS pathway was also characterized by the use of other inhibitors. This finding indicates that phospholipase A2 and 5-lipoxygenase are also involved. However, the NF-kappaB activation pathway involving the acidic sphingomyelinase of the endolysosomial membrane did not seem to participate in the LPS-induced NF-kappaB activation in U937 cells.
Legrand-Poels
S
S
Laboratory of Fundamental Virology, Université de Liège, Belgium.
Maniglia
S
S
Boelaert
J R
JR
Piette
J
J
D000975:Antioxidants / Q000494:pharmacology; D001692:Biological Transport / Q000187:drug effects; D002460:Cell Line; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D007375:Interleukin-1 / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008084:Lipoxygenase / Q000502:physiology; D009000:Monocytes / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism*; D010741:Phospholipases A / Q000502:physiology; D054467:Phospholipases A2; D015398:Signal Transduction; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D000975:Antioxidants; D007375:Interleukin-1; D008070:Lipopolysaccharides; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; D006861:Hydrogen Peroxide; D008084:Lipoxygenase; D010741:Phospholipases A; D054467:Phospholipases A2