Increased glutathione levels in quiescent, serum-stimulated NRK-49F cells are associated not with a response to growth factors but with nutrient repletion.
Treatment of quiescent cells with serum results concomitantly in an increase in cellular glutathione (GSH) content and growth stimulation. A possible association between the GSH increase and the growth response was examined by studying separately the effects of nutrients and growth factors on the levels of cellular GSH and proliferation of quiescent NRK-49F cells. The addition of fresh medium with 10% calf serum was found to result in both a twofold increase in cellular GSH and growth stimulation (DNA synthesis and cell proliferation). 10% calf serum alone, without fresh medium, stimulated cell growth but failed to cause a comparable increase in cellular GSH. The addition of fresh medium without 10% serum, and of 0.5 mM cysteine and glutamate, resulted in both instances in a marked increase in cellular GSH, but failed to stimulate cell growth. EGF, in contrast, induced a complete mitogenic response but did not increase cellular GSH. Finally, pretreatment with L-buthionine-(S,R)-sulfoximine (BSO), a specific inhibitor of GSH synthesis, decreased cellular GSH and inhibited EGF-induced DNA synthesis, but these two responses do not, in their dose dependency, correlate. The results obtained thus show that the increase in cellular GSH that occurs in quiescent, serum-stimulated NRK-49F cells is a result of nutrient repletion rather than mitogenic stimulation, and increased GSH levels do not necessarily precede DNA synthesis and mitosis.
Department of Zoology and Genetics, Iowa State University, Ames 50011.
Y J
YJ
Kang
M D
MD
Enger
D000818:Animals; D001769:Blood; D019328:Buthionine Sulfoximine; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D003470:Culture Media; D003545:Cysteine / Q000494:pharmacology; D004247:DNA / Q000096:biosynthesis; D004815:Epidermal Growth Factor / Q000494:pharmacology; D005971:Glutamates / Q000494:pharmacology; D018698:Glutamic Acid; D005978:Glutathione / Q000378:metabolism*; D006133:Growth Substances / Q000494:pharmacology*; D007399:Interphase; D008717:Methionine Sulfoximine / Q000031:analogs & derivatives / Q000494:pharmacology
D003470:Culture Media; D005971:Glutamates; D006133:Growth Substances; D008717:Methionine Sulfoximine; D018698:Glutamic Acid; D019328:Buthionine Sulfoximine; D004815:Epidermal Growth Factor; D004247:DNA; D005978:Glutathione; D003545:Cysteine