title: Mechanism of extracellular signal-regulated kinase (ERK)-1 and ERK-2 activation by vanadium pentoxide in rat pulmonary myofibroblasts.
abstract: Vanadium pentoxide (V(2)O(5)) is a cause of occupational asthma and chronic bronchitis, yet the molecular mechanisms through which V(2)O(5) exerts its effects on cell function are unclear. In this study we investigated the potential of V(2)O(5) to activate the extracellular signal-regulated kinases 1 and 2 (ERK-1/2) in rat pulmonary myofibroblasts. Treatment of myofibroblasts with V(2)O(5) resulted in the activation of ERK-1/2, yet the inert metal titanium dioxide had no effect on ERK-1/2 activation. V(2)O(5)-induced ERK-1/2 activation was abolished by pretreatment with forskolin or PD98059, indicating a dependence on Raf and mitogen-activated protein (MAP) kinase kinase, respectively. Depletion of conventional protein kinase C activity with phorbol 12-myristate 13-acetate did not inhibit V(2)O(5)-induced ERK-1/2 activation. ERK-1/2 activation by V(2)O(5) was inhibited > 70% with the epidermal growth factor receptor (EGF-R) tyrosine kinase inhibitor AG1478. Phosphorylation of the 170-kD EGF-R by V(2)O(5) was detected after immunoprecipitation with an anti-EGF-R antibody followed by phosphotyrosine Western blotting. V(2)O(5) strongly tyrosine-phosphorylated a 115-kD protein (p115) and activation of p115 was inhibited 60 to 70% by AG1478, indicating that this protein was an EGF-R substrate. Phosphorylation of p115 was also observed in EGF-stimulated cells. Immunoprecipitation of V(2)O(5)- or EGF-treated cell lysates with an antibody against Src homology 2 protein tyrosine phosphatase (SH-PTP2) identified p115 as a SH-PTP2-binding protein. Pretreatment of cells with the antioxidant N-acetyl-L-cysteine blocked V(2)O(5)-induced MAP kinase activation and p115 phosphorylation > 90%. These data suggest that V(2)O(5) activation of ERK-1/2 is oxidant-dependent and mediated through tyrosine phosphorylation of EGF-R and an EGF-R substrate which we identified as a 115-kD SH-PTP2-binding protein.
authors.affiliation: Airway Inflammation Section, Laboratory of Pulmonary Pathobiology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709, USA.
authors.forename: Y Z
authors.initials: YZ
authors.lastname: Wang
authors.forename: J C
authors.initials: JC
authors.lastname: Bonner
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D000818:Animals; D001249:Asthma / Q000209:etiology; D001991:Bronchitis / Q000209:etiology; D002244:Carbon / Q000009:adverse effects; D060729:Coal Ash; D005576:Colforsin / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D066246:ErbB Receptors / Q000378:metabolism; D005347:Fibroblasts; D005419:Flavonoids / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins; D008168:Lung / Q000201:enzymology*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D052638:Particulate Matter; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism; D011799:Quinazolines; D051381:Rats; D014025:Titanium / Q000494:pharmacology; D020032:Tyrphostins / Q000494:pharmacology; D017968:Vanadium Compounds / Q000494:pharmacology*
chemical_list: D060729:Coal Ash; D005419:Flavonoids; D047908:Intracellular Signaling Peptides and Proteins; D052638:Particulate Matter; D011799:Quinazolines; D020032:Tyrphostins; D017968:Vanadium Compounds; C009495:titanium dioxide; C101044:RTKI cpd; D005576:Colforsin; D019000:Phosphotyrosine; D002244:Carbon; C066075:vanadium pentoxide; D014025:Titanium; D066246:ErbB Receptors; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases; C516727:Ptpn11 protein, rat; C509250:Ptpn6 protein, rat; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; D000111:Acetylcysteine