Importance of post-transcriptional regulation of chemokine genes by oxidative stress.
The transcription factor, nuclear factor kappa B (NF-kappa B), is activated by various stimuli including cytokines, radiation, viruses and oxidative stress. Here we show that, although induction with H(2)O(2) gives rise to NF-kappa B nuclear translocation in both lymphocyte (CEM) and monocyte (U937) cells, it leads only to the production of mRNA species encoding interleukin-8 (IL-8) and macrophage inflammatory protein 1 alpha in U937 cells. Under similar conditions these mRNA species are not observed in CEM cells. With the use of a transient transfection assay of U937 cells transfected with reporter constructs of the IL-8 promoter and subsequently treated with H(2)O(2), we show that (1) IL-8-promoter-driven transcription is stimulated in both U937 and CEM cells and (2) the NF-kappa B site is crucial for activation because its deletion abolishes activation by H(2)O(2). The production of IL-8 mRNA in U937 cells is inhibited by the NF-kappa B inhibitors clasto-lactacystin-beta-lactone and E-64D (l-3-trans-ethoxycarbonyloxirane-2-carbonyl-L-leucine-3-methyl amide) but requires protein synthesis de novo. Moreover, inhibition of the p38 mitogen-activated protein kinase also decreases the IL-8 mRNA up-regulation mediated by H(2)O(2). Taken together, these results show the importance of post-transcriptional events controlled by a p38-dependent pathway in the production of IL-8 mRNA in U937. The much lower activation of p38 in CEM cells in response to H(2)O(2) could explain the lack of stabilization of IL-8 mRNA in these cells.
Josse
C
C
Laboratory of Virology and Immunology, Institute of Pathology B23, University of Liège, B-4000 Liège, Belgium.
Boelaert
J R
JR
Best-Belpomme
M
M
Piette
J
J
D002474:Cell-Free System / Q000187:drug effects / Q000378:metabolism; D018932:Chemokine CCL2 / Q000235:genetics / Q000378:metabolism; D018925:Chemokines / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism*; D004789:Enzyme Activation / Q000235:genetics; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D016209:Interleukin-8 / Q000235:genetics / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects / Q000235:genetics*; D011401:Promoter Regions, Genetic; D011485:Protein Binding / Q000235:genetics; D012323:RNA Processing, Post-Transcriptional / Q000187:drug effects; D012333:RNA, Messenger / Q000096:biosynthesis / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects; D014407:Tumor Cells, Cultured; D020298:U937 Cells / Q000187:drug effects / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases
D018932:Chemokine CCL2; D018925:Chemokines; D016209:Interleukin-8; D016328:NF-kappa B; D012333:RNA, Messenger; D006861:Hydrogen Peroxide; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases