title: Selective activation of the mitogen-activated protein kinase subgroups c-Jun NH2 terminal kinase and p38 by IL-1 and TNF in human articular chondrocytes.
abstract: Previous studies suggested that tyrosine kinase activation is an important signal transduction event in the IL-1 response of chondrocytes. The present study identifies the mitogen-activated protein (MAP) kinases extracellular signal-regulated kinase (ERK)-1 and ERK-2 as major tyrosine phosphorylated proteins in IL-1 stimulated chondrocytes. Kinase assays on immunoprecipitates with myelin basic protein as substrate showed that ERK-1 and ERK-2 activation was detectable within 5 min after IL-1 stimulation and decreased to baseline within 60 min. Analysis of other members of the MAP kinase family showed that chondrocytes also express c-Jun NH2 terminal kinase (JNK)-1, JNK-2, and p38 proteins. These kinases were time-dependently activated by IL-1. Among other chondrocyte activators tested, only TNF activated all three of the MAP kinase subgroups. JNK and p38 were not activated by any of the other cytokines and growth factors tested. However, ERK was also activated by PDGF, IGF-1, and IL-6. Phorbol 12-myristate 13-acetate, calcium ionophore, and cAMP analogues only increased ERK activity but had no significant effects on JNK or p38. These results suggest differential activation of MAP kinase subgroups by extracellular stimuli. ERK is activated in response to qualitatively diverse extracellular stimuli and various second messenger agonists. In contrast, JNK and p38 are only activated by IL-1 or TNF, suggesting that these kinases participate in the induction of the catabolic program in cartilage.
authors.affiliation: Sam and Rose Stein Institute for Research on Aging, Department of Medicine, University of California, San Diego, La Jolla 92093-0663, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Geng
authors.forename: J
authors.initials: J
authors.lastname: Valbracht
authors.forename: M
authors.initials: M
authors.lastname: Lotz
mesh_terms: D002118:Calcium / Q000494:pharmacology; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002356:Cartilage / Q000166:cytology / Q000378:metabolism*; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000494:pharmacology; D006801:Humans; D015151:Immunoblotting; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology; D015850:Interleukin-6 / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048056:Mitogen-Activated Protein Kinase 9; D020929:Mitogen-Activated Protein Kinase Kinases; D020928:Mitogen-Activated Protein Kinases; D004676:Myelin Basic Protein / Q000276:immunology / Q000378:metabolism; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology; D011494:Protein Kinases / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D015398:Signal Transduction; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D007375:Interleukin-1; D015850:Interleukin-6; D004676:Myelin Basic Protein; D010982:Platelet-Derived Growth Factor; D014409:Tumor Necrosis Factor-alpha; D007334:Insulin-Like Growth Factor I; D000242:Cyclic AMP; D011494:Protein Kinases; D048056:Mitogen-Activated Protein Kinase 9; D011505:Protein-Tyrosine Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium