Glutathione stimulates A549 cell proliferation in glutamine-deficient culture: The effect of glutamate supplementation
✍ Scribed by Y. James Kang; Yi Feng; Emiko L. Hatcher
- Publisher
- John Wiley and Sons
- Year
- 1994
- Tongue
- English
- Weight
- 964 KB
- Volume
- 161
- Category
- Article
- ISSN
- 0021-9541
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✦ Synopsis
Extracellular glutathione (GSH) is degraded by an external cell-surface enzyme, y-glutamyltranspeptidase (y-GT). The products are transported into cells to participate in important cellular processes. In the present study, we tested the hypothesis that extracellular GSH is a source of glutamic acid for cells that express y-GT. Under a glutamine-deficient culture condition, the extracellular GSH-supplemented glutamic acid would enhance intracellular glutamine synthesis, thereby stimulating cell proliferation. Human lung carcinoma A549 cells were cultured in glutamine-deficient Dulbecco's modified Eagle medium, and they did not proliferate unless glutamine was supplemented. Extracellular GSH, however, provoked a partial proliferation. The GSH effect correlated with a high level of y-GT activity and an increased intracellular level of glutamic acid. A constituent amino acid of