Am. J. Respir. Cell Mol. Biol.,
Volume 27, Number 1, July, 2002 99-106
Inhibition of Glutamine Synthetase in A549 Cells During Hyperoxia
Sharon A.
McGrath-Morrow
and
Jennifer
Stahl
Department of Pediatrics, Eudowood Division of Pediatric Respiratory Sciences, Johns Hopkins Medical Institutions, Baltimore, Maryland
High oxygen concentrations are used in the treatment of
acute respiratory distress syndrome and hyaline membrane disease. Hyperoxia, however, can damage alveolar epithelial cells
through the release of free oxygen radicals. Supplemental
glutamine (Gln) has recently been shown to increase survival
of A549 cells, a distal epithelial cell line, during hyperoxia ().
We found that supplemental Gln (Gln+) is essential for cell
growth in A549 cells. In room air, cells without supplemental
Gln (Gln
) survived with BCL-2 levels similar to those of Gln+
cells, but cell growth was minimal. We also evaluated the role
of glutamine synthetase (GS) in A549 cells during hyperoxia.
L-methionine sulfoximine (MSO), an irreversible inhibitor of
GS, was added to Gln+ and Gln cells. In hyperoxia, Gln
cells had greater survival then Gln cells treated with MSO.
Supplemental Gln could rescue cells in hyperoxia from the effect of MSO, suggesting that GS, through the endogenous
synthesis of Gln, could attenuate hyperoxic cell injury. In hyperoxia, cells treated with 10-mM concentrations of Gln had
increased survival compared with cells receiving 2-mM concentrations. The higher concentration of Gln, however, did not decrease the percentage of cells undergoing necrosis.
Abbreviations: L-buthionine-[S,R]-sulfoximine, BSO; bromodeoxyuridine, BRDU; enhanced chemiluminescence, ECL; fetal bovine serum,
FBS; glutamine, Gln; Gln synthetase, GS; glutathione, GSH; heat shock
protein-70, HSP70; mitochondrial membrane permeability, MMP; L-methionine sulfoximine, MSO; phosphate-buffered saline, PBS; proliferating cell
nuclear antigen, PCNA.
