Tpl-2 induces IL-2 expression in T-cell lines by triggering multiple signaling pathways that activate NFAT and NF-kappaB.
The Tpl-2 kinase activates the nuclear factor of activated T cells (NFAT) and induces IL-2 expression in T-cell lines. Here we show that the activation of the IL-2 promoter by Tpl-2 is inhibited by mutant signaling molecules that inhibit the mitogen-activated protein kinase (MAPK) or the calcineurin/NFAT pathways and is promoted by combinations of signaling molecules that activate these pathways. We, therefore, conclude that signals generated by the convergence of the MAPK and the calcineurin/NFAT pathway are necessary and sufficient for the activation of the IL-2 promoter by Tpl-2. The activation of both the IL-2 promoter and an NFAT-driven minimal promoter were shown to depend on signals transduced by Raf1. However, it was only the IL-2 promoter whose activation by Tpl-2 was fully blocked by the dominant negative mutant MEK1S218/222A and the MEK1/MEK2 inhibitor PD098059. Since the activation of NFAT is MAPK-dependent these findings suggested that the activation of MAPK by Tpl-2 is either independent or only partially dependent on MEK1 and MEK2. In addition, they suggested that the activation of the IL-2 promoter is under the control of not only NFAT but also a second factor whose activation is MEK-dependent. Experiments in COS-1 and EL-4 cells confirmed both hypotheses and revealed that the second factor activated by Tpl-2 is NF-kappaB. While the activation of the IL-2 promoter and an NFAT-driven minimal promoter by Tpl-2 was fully blocked by the dominant negative mutant NFAT delta418, it was only partially blocked by the calcineurin inhibitor cyclosporin A suggesting that the Tpl-2-mediated NFAT activation is under the control of a combination of calcineurin-dependent and independent pathways. Both pathways were fully blocked by Bcl-2 or Bcl-X(L).
Tsatsanis
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Department of Microbiology and Immunology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
Patriotis
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Tsichlis
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D000818:Animals; D019556:COS Cells; D019703:Calcineurin / Q000502:physiology*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism / Q000502:physiology; D016572:Cyclosporine / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000502:physiology*; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology; D007376:Interleukin-2 / Q000096:biosynthesis* / Q000235:genetics; D019169:Jurkat Cells; D016399:Lymphoma, T-Cell / Q000473:pathology; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; D020930:MAP Kinase Kinase Kinases; D051379:Mice; D048052:Mitogen-Activated Protein Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases; D020928:Mitogen-Activated Protein Kinases; D016328:NF-kappa B / Q000378:metabolism*; D050778:NFATC Transcription Factors; D009363:Neoplasm Proteins / Q000502:physiology; D009687:Nuclear Proteins; D011401:Promoter Regions, Genetic; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D011505:Protein-Tyrosine Kinases / Q000502:physiology; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000502:physiology; D019908:Proto-Oncogene Proteins c-raf / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology*; D013601:T-Lymphocytes / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured; D051020:bcl-X Protein
C494811:BCL2L1 protein, human; C494812:Bcl2l1 protein, mouse; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D005419:Flavonoids; D007166:Immunosuppressive Agents; D007376:Interleukin-2; D016328:NF-kappa B; D050778:NFATC Transcription Factors; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D014157:Transcription Factors; D051020:bcl-X Protein; D016572:Cyclosporine; C482128:MAP2K2 protein, human; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D019908:Proto-Oncogene Proteins c-raf; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D020930:MAP Kinase Kinase Kinases; C069937:MAP3K8 protein, human; C489843:Map3k8 protein, mouse; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; C482125:MAP2K1 protein, human; C482127:Map2k1 protein, mouse; D020929:Mitogen-Activated Protein Kinase Kinases; D019703:Calcineurin; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one