The p38 MAP kinase inhibitor SB203580 enhances nuclear factor-kappa B transcriptional activity by a non-specific effect upon the ERK pathway.
In the present study we investigated a possible role for the p38 mitogen-activated protein (MAP) kinase pathway in mediating nuclear factor-kappa B (NF-kappaB) transcriptional activity in the erythroleukaemic cell line TF-1. TF-1 cells stimulated with the phosphatase inhibitor okadaic acid (OA) demonstrated enhanced NF-kappaB and GAL4p65-regulated transcriptional activity which was associated with elevated p38 phosphorylation. However, pretreatment with the p38 MAPK specific inhibitor SB203580 (1 microM) or overexpression of kinase-deficient mutants of MKK3 or MKK6 did not affect OA-enhanced NF-kappaB transcriptional potency, as determined in transient transfection assays. In fact, 5 and 10 microM SB203580 enhanced rather than inhibited NF-kappaB-mediated promoter activity by 2 fold, which was independent of phosphorylation of the p65 subunit. The SB203580-mediated increase in NF-kappaB transcriptional activity was associated with enhanced phosphorylation of extracellular signal-regulated kinase (ERK)1/2 and c-Jun N-terminal kinase (JNK), but not p38 kinase. Overexpression of kinase-deficient mutants belonging to the ERK1/2, JNK, and p38 pathways showed that only dominant-negative Raf-1 abrogated SB203580-enhanced NF-kappaB activity. This would implicate the involvement of the ERK1/2 pathway in the enhancing effects of SB203580 on NF-kappaB-mediated gene transcription. This study demonstrates that the p38 MAP kinase pathway is not involved in the OA-induced activation of NF-kappaB. SB203580 at higher concentrations activates the ERK pathway, which subsequently enhances NF-kappaB transcriptional activity.
Birkenkamp
K U
KU
Division of Hematology, Department of Medicine, University of Groningen, PO Box 30 001, 9700 RB Groningen, The Netherlands.
Tuyt
L M
LM
Lummen
C
C
Wierenga
A T
AT
Kruijer
W
W
Vellenga
E
E
D004247:DNA / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology*; D048371:MAP Kinase Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases / Q000502:physiology; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*; D016328:NF-kappa B / Q000378:metabolism*; D019319:Okadaic Acid / Q000494:pharmacology; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D011505:Protein-Tyrosine Kinases / Q000502:physiology; D019908:Proto-Oncogene Proteins c-raf / Q000502:physiology; D011725:Pyridines / Q000494:pharmacology*; D015533:Transcriptional Activation / Q000187:drug effects*; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases
D004791:Enzyme Inhibitors; D007093:Imidazoles; D016328:NF-kappa B; D011725:Pyridines; D014409:Tumor Necrosis Factor-alpha; D019319:Okadaic Acid; D004247:DNA; D011505:Protein-Tyrosine Kinases; D019908:Proto-Oncogene Proteins c-raf; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048371:MAP Kinase Kinase 3; C482530:MAP2K3 protein, human; D020929:Mitogen-Activated Protein Kinase Kinases; C093642:SB 203580