title: p38 mitogen-activated protein kinase regulates growth factor-induced mitogenesis of rat pulmonary myofibroblasts.
abstract: Myofibroblast proliferation is a central feature of pulmonary fibrogenesis. Several growth factors, including platelet-derived growth factor (PDGF) and epidermal growth factor (EGF), stimulate myofibroblast growth by activating extracellular signal regulated kinases 1 and 2 (ERK1/2). In this report, we demonstrate that PDGF-BB and EGF also activate the p38 mitogen-activated protein (MAP) kinase. Inhibition of p38 activity with the pyridinylimidazole compound SB203580 enhanced both PDGF-BB and EGF-stimulated DNA synthesis in rat lung myofibroblasts. ERK1/2 phosphorylation in response to either PDGF-BB or EGF treatment was significantly increased by pretreatment of cells with SB203580. We also demonstrated that ERK1/2-induced phosphorylation of PHAS-1 substrate was enhanced by inhibition of p38 MAP kinase with SB203580. However, SB203580 did not significantly increase growth factor-induced activation of MEK, the upstream kinase that phosphorylates ERK1/2. p38 MAP kinase was co-immunoprecipitated with ERK-1/2 following growth factor stimulation. Collectively, these data demonstrate that p38 MAP kinase activation negatively regulates PDGF- and EGF-mediated growth responses by directly interacting with ERK1/2 and suppressing its phosphorylation.
authors.affiliation: Airway Inflammation Group, Laboratory of Pulmonary Pathobiology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, USA.
authors.forename: Annette B
authors.initials: AB
authors.lastname: Rice
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Ingram
authors.forename: James C
authors.initials: JC
authors.lastname: Bonner
mesh_terms: D000818:Animals; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004815:Epidermal Growth Factor / Q000494:pharmacology; D005347:Fibroblasts / Q000166:cytology* / Q000201:enzymology*; D006133:Growth Substances / Q000494:pharmacology*; D007093:Imidazoles / Q000494:pharmacology; D008168:Lung / Q000166:cytology*; D008297:Male; D019950:Mitogen-Activated Protein Kinase 1 / Q000032:analysis / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000032:analysis / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology; D011233:Precipitin Tests; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D004791:Enzyme Inhibitors; D006133:Growth Substances; D007093:Imidazoles; D010982:Platelet-Derived Growth Factor; D011725:Pyridines; D004815:Epidermal Growth Factor; D017346:Protein Serine-Threonine Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C093642:SB 203580