title: Divergent roles for Ras and Rap in the activation of p38 mitogen-activated protein kinase by interleukin-1.
abstract: We have found that lethal toxin from Clostridium sordellii, which specifically inactivates the low molecular weight G proteins Ras, Rap, and Rac, inhibits the activation of p38 mitogen-activated protein kinase (MAPK) by interleukin-1 (IL-1) in EL4.NOB-1 cells and primary fibroblasts. The target protein involved appeared to be Ras, because transient transfections with dominant negative RasN17 inhibited p38 MAPK activation by IL-1. Furthermore, transfections of cells with constitutively active RasVHa-activated p38 MAPK. Further evidence for Ras involvement came from the observation that IL-1 caused a rapid activation of Ras in the cells and from the inhibitory effects of the Ras inhibitors manumycin A and damnacanthal. Toxin B from Clostridium difficile, which inactivates Rac, Cdc42, and Rho, was without effect. Dominant negative versions of Rac (RacN17) or Rap (Rap1AN17) did not inhibit the response. Intriguingly, transfection of cells with dominant negative Rap1AN17 activated p38 MAPK. Furthermore, constitutively active Rap1AV12 inhibited p38 MAPK activation by IL-1, consistent with Rap antagonizing Ras function. IL-1 also activated Rap in the cells, but with slower kinetics than Ras. Our studies therefore provide clear evidence using multiple approaches for Ras as a signaling component in the activation of p38 MAPK by IL-1, with Rap having an inhibitory effect.
authors.affiliation: Department of Biochemistry, Biotechnology Institute, Trinity College, Dublin 2, Ireland.
authors.forename: E M
authors.initials: EM
authors.lastname: Palsson
authors.forename: M
authors.initials: M
authors.lastname: Popoff
authors.forename: M
authors.initials: M
authors.lastname: Thelestam
authors.forename: L A
authors.initials: LA
authors.lastname: O'Neill
mesh_terms: D000818:Animals; D000880:Anthraquinones / Q000494:pharmacology; D001426:Bacterial Proteins; D001427:Bacterial Toxins / Q000494:pharmacology; D022762:CCAAT-Enhancer-Binding Proteins; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D004789:Enzyme Activation; D004792:Enzyme Precursors / Q000378:metabolism; D020672:I-kappa B Proteins; D007375:Interleukin-1 / Q000494:pharmacology*; D051379:Mice; D020928:Mitogen-Activated Protein Kinases; D008954:Models, Biological; D000072000:NF-KappaB Inhibitor alpha; D010766:Phosphorylation; D011090:Polyenes / Q000494:pharmacology; D053284:Polyunsaturated Alkamides; D011499:Protein Processing, Post-Translational; D051742:Transcription Factor CHOP; D014157:Transcription Factors / Q000378:metabolism; D014407:Tumor Cells, Cultured; D048051:p38 Mitogen-Activated Protein Kinases; D020668:rap GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D018631:ras Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D000880:Anthraquinones; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; C497250:Ddit3 protein, mouse; D004792:Enzyme Precursors; D020672:I-kappa B Proteins; D007375:Interleukin-1; C000606205:Nfkbia protein, mouse; D011090:Polyenes; D053284:Polyunsaturated Alkamides; D014157:Transcription Factors; C072292:lethal toxin LT, Clostridium sordellii; C031815:toxB protein, Clostridium difficile; D000072000:NF-KappaB Inhibitor alpha; D051742:Transcription Factor CHOP; C079170:damnacanthal; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases; D020668:rap GTP-Binding Proteins; D018631:ras Proteins; C054474:manumycin