Inhibition of p38 MAP kinase increases okadaic acid mediated AP-1 expression and DNA binding but has no effect on TRE dependent transcription.
By performing in vitro kinase assays we found in papilloma producing 308 mouse keratinocytes that okadaic acid elevated activities of extracellular signal-regulated kinase (ERK) 1/2, c-Jun N-terminal kinases (JNKs) and p38 mitogen-activated protein kinases (MAPKs). This okadaic acid mediated activation of MAP kinases correlated with increased AP-1 binding to a consensus TPA responsive element (TRE) and elevated TRE dependent transcription. To determine the role of p38 MAP kinases in these processes we employed the specific p38 MAP kinase inhibitor SB 203580. Using orthophosphate labeling we showed a decrease in phosphorylation of MAPK activated protein kinase-2 (MAPKAP-K2) indicating reduced activity of p38 MAPKs utilizing this kinase as substrate. In contrast, we found that SB 203580 raised activities of ERK-1/2 and JNKs. Electrophoretic mobility shift assays revealed an increase in TRE binding activity in response to SB 203580 most likely resulting from increased expression of the major TRE binding components JunD and FosB as indicated by Western blot analyses. Increased TRE DNA binding failed to lead to increased transactivation correlating with the inability of SB 203580 to increase phosphorylation of these AP-1 proteins. These data indicate that SB 203580 sensitive p38 MAP kinases are not involved in okadaic acid mediated increases in TRE DNA binding and transactivation.
Rosenberger
S F
SF
Department of Radiation Oncology, The University of Arizona Health Sciences Center, Tucson 85724, USA.
Gupta
A
A
Bowden
G T
GT
D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D016384:Consensus Sequence / Q000235:genetics; D004247:DNA / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D007093:Imidazoles / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases; D015603:Keratinocytes / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D048670:MAP Kinase Kinase 4; D051379:Mice; D020929:Mitogen-Activated Protein Kinase Kinases; D020928:Mitogen-Activated Protein Kinases; D019319:Okadaic Acid / Q000494:pharmacology*; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding / Q000187:drug effects; D011494:Protein Kinases / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology; D020218:Response Elements / Q000235:genetics; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D018808:Transcription Factor AP-1 / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects*; D015533:Transcriptional Activation / Q000187:drug effects; D048051:p38 Mitogen-Activated Protein Kinases
D004268:DNA-Binding Proteins; D007093:Imidazoles; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D011725:Pyridines; D018808:Transcription Factor AP-1; D019319:Okadaic Acid; D004247:DNA; D011494:Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases; D013755:Tetradecanoylphorbol Acetate; C093642:SB 203580