© 2002 American Thoracic Society Oxidant-Induced Hypertrophy of A549 Cells Is Accompanied by Alterations in Eukaryotic Translation Initiation Factor 4E and 4E-Binding Protein-1Department of Pediatrics, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire; and Departments of Anatomy/Neurobiology and Microbiology/Immunology, University of Kentucky, Lexington, Kentucky Address correspondence to: Jeffrey S. Shenberger, M.D., Department of Pediatrics/Neonatology, Dartmouth-Hitchcock Medical Center, One Medical Center Drive, Lebanon, NH 03756. E-mail: Jeffrey.S.Shenberger{at}Dartmouth.edu Control of protein synthesis resides at the level of eukaryotic translation initiation (eIF) complex formation. Complex formation is regulated by the mRNA cap-binding protein, eIF4E, whose activity is influenced by phosphorylation and binding to 4E-binding protein 1 (4E-BP1). To provide a link between alterations in protein synthesis and the pathogenesis of oxidant-mediated lung disease, we investigated the effect of hydrogen peroxide (H2O2) on actively growing A549 cells. Cells were exposed to 200 or 400 µM H2O2 for 4 h and then assessed for changes in proliferation, protein synthesis, and eIF4E and 4E-BP1 status over 72 h. We found that both concentrations of H2O2 inhibited [3H]thymidine incorporation and cell division while inducing a G2/M-predominant growth arrest within 24 h. In addition, H2O2 increased cell size, [3H]leucine incorporation/cell, and total cell protein. Although time had little effect on eIF4E and 4E-BP1 expression and phosphorylation state of control cells, H2O2 induced a 2- to 3-fold increase in eIF4E and 4E-BP1 expression, a 5-fold increase in eIF4E phosphorylation, and a shift in the distribution of 4E-BP1 phosphorylation favoring lesser phosphorylated forms. These findings suggest that oxidant-mediated alterations in protein synthesis and cell morphology occur in concert with changes in factors known to regulate translation kinetics.
Abbreviations: bronchopulmonary dysplasia, BPD • 4E-binding protein 1, 4E-BP1 • enhanced chemiluminescence, ECL • eukaryotic translation initiation, eIF • lactate dehydrogenase, LDH • mitogen-activated protein kinase, MAPK • phosphate-buffered saline, PBS • reactive oxygen species, ROS • trichloroacetic acid, TCA This article has been cited by other articles:
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