The p38 mitogen-activated protein kinase regulates interleukin-1beta-induced IL-8 expression via an effect on the IL-8 promoter in intestinal epithelial cells.
Several lines of evidence implicate the p38 mitogen-activated protein kinase (p38 MAPK) in the proinflammatory response to bacterial agents and cytokines. Equally, the transcription factor, nuclear factor (NF)-kappaB, is recognized to be a critical determinant of the inflammatory response in intestinal epithelial cells (IECs). However, the precise inter-relationship between the activation of p38 MAPK and activation of the transcription factor NF-kappaB in the intestinal epithelial cell (IEC) system, remains unknown. Here we show that interleukin (IL)-1beta activates all three MAPKs in Caco-2 cells. The production of IL-8 and monocyte chemotactic protein 1 (MCP-1) was attenuated by 50% when these cells were preincubated with the p38 MAPK inhibitor, SB 203580. Further investigation of the NF-kappaB signalling system revealed that the inhibitory effect was independent of the phosphorylation and degradation of IkappaBalpha, the binding partner of NF-kappaB. This effect was also independent of the DNA binding of the p65 Rel A subunit, as well as transactivation, determined by an NF-kappaB luciferase construct, using both SB 203580 and dominant-negative p38 MAPK. Evaluation of IL-8 and MCP-1 RNA messages by reverse transcription-polymerase chain reaction (RT-PCR) revealed that the inhibitory effect of SB 203580 was associated with a reduction in this parameter. Using an IL-8-luciferase promoter construct, an effect of p38 upon its activation by both pharmacological and dominant-negative p38 construct co-transfection was demonstrated. It is concluded that p38 MAPK influences the expression of chemokines in intestinal epithelial cells, through an effect upon the activation of the chemokine promoter, and does not directly involve the activation of the transcription factor NF-kappaB.
Parhar
Kuljit
K
Department of Medicine, The Jack Bell Research Centre, Vancouver, British Columbia, Canada.
Ray
Andrew
A
Steinbrecher
Urs
U
Nelson
Colleen
C
Salh
Baljinder
B
D002460:Cell Line; D018932:Chemokine CCL2 / Q000096:biosynthesis; D004268:DNA-Binding Proteins / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000276:immunology; D006801:Humans; D020672:I-kappa B Proteins / Q000378:metabolism; D007093:Imidazoles / Q000494:pharmacology; D007375:Interleukin-1 / Q000276:immunology*; D016209:Interleukin-8 / Q000096:biosynthesis*; D007413:Intestinal Mucosa / Q000276:immunology*; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000276:immunology* / Q000378:metabolism / Q000502:physiology; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism; D010766:Phosphorylation; D011725:Pyridines / Q000494:pharmacology; D015533:Transcriptional Activation / Q000276:immunology; D048051:p38 Mitogen-Activated Protein Kinases
D018932:Chemokine CCL2; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D020672:I-kappa B Proteins; D007093:Imidazoles; D007375:Interleukin-1; D016209:Interleukin-8; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D011725:Pyridines; D000072000:NF-KappaB Inhibitor alpha; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C093642:SB 203580