© 2003 American Thoracic Society DOI: 10.1165/rcmb.2002-0013OC Asbestos Inhalation Induces Tyrosine Nitration Associated with Extracellular Signal-Regulated Kinase 1/2 Activation in the Rat LungDepartment of Pathology, Uniformed Services University of the Health Sciences, Bethesda, Maryland; and Department of Civil and Environmental Engineering, University of Vermont, Burlington, Vermont Address correspondence to: Elliott Kagan, M.D., Department of Pathology, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814-4799. E-mail: ekagan{at}usuhs.mil Nitration of proteins by peroxynitrite (ONOO-) has been shown to critically alter protein function in vitro. We have shown previously that asbestos inhalation induced nitrotyrosine formation, a marker of ONOO- production, in the rat lung. To determine whether asbestos-induced protein nitration may affect mitogen-activated protein kinase (MAPK) signaling pathways, lung lysates from crocidolite and chrysotile asbestos-exposed rats and from sham-exposed rats were immunoprecipitated with anti-nitrotyrosine antibody, and captured proteins were subjected to Western blotting with anti–phospho-extracellular signal-regulated kinase (ERK)1/2 antibodies. Both types of asbestos inhalation induced significantly greater phosphorylation of ERK1/2 in rat lung lysates than was noted after sham exposure. Phosphorylated ERK proteins co-immunoprecipitated with nitrotyrosine. Moreover, in MAPK functional assays using Elk-1 substrate, immunoprecipitated phospho-ERK1/2 in lung lysates from both crocidolite-exposed and chrysotile-exposed rats demonstrated significantly greater phosphorylation of Elk-1 than was noted after sham exposure. Asbestos inhalation also induced ERK phosphorylation in bronchoalveolar lavage cells. Lung sections from rats exposed to crocidolite or chrysotile (but not from sham-exposed rats nor from rats exposed to "inert" carbonyl iron particles) demonstrated strong immunoreactivity for nitrotyrosine and phospho-ERK1/2 in alveolar macrophages and bronchiolar epithelium. These findings suggest that asbestos fibers may activate the ERK signaling pathway by generating ONOO- or other nitrating species that induce tyrosine nitration and phosphorylation of critical signaling molecules.
Abbreviations: bovine serum albumin, BSA • bronchoalveolar lavage, BAL • epidermal growth factor receptor, EGFR • extracellular signal-related kinase, ERK • fetal bovine serum, FBS • inducible form of nitric oxide synthase, iNOS • mitogen-activated protein kinase, MAPK • mitogen-activated protein kinase kinase/ERK kinase, MEK-1 • nitric oxide, •NO • nuclear factor- This article has been cited by other articles:
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