Synthesis of hsp-70 is enhanced in glutathione-depleted Hep G2 cells.
The question of whether depletion of glutathione (GSH) could affect the synthesis of stress proteins was investigated in Hep G2 cells. Cells were exposed to BSO/DEM at 37 degrees C to deplete glutathione. When 95% of the glutathione was depleted cells were washed, and BSO was added to cells previously exposed to BSO/DEM; then the cells were incubated at 37, 38.5, or 39 degrees C for 4 h. Two-dimensional PAGE analysis of GSH-depleted cells incubated at 37 degrees C indicated increased synthesis of heme oxygenase and a polypeptide tentatively identified as hsp-70B'. Depletion of GSH did not affect the cellular concentration of hsp-70 as assessed by Western immunoblotting, yet Northern blot analysis indicated that hsp-70 mRNA was increased in GSH-depleted cells. Incubation of GSH-replete cells at 38.5 degrees C did not appear to enhance the amount of hsp-70 mRNA or the relative rate of hsp-70 synthesis. In contrast, incubation of GSH-depleted cells at 38.5 degrees C elevated steady-state hsp-70 mRNA levels and the rate of hsp-70 synthesis relative to total protein synthesis. Depletion of GSH also increased the relative rate of hsp-70 synthesis at 39 degrees C. These results suggest that the synthesis of stress proteins can be affected by glutathione concentrations.
Vanderbilt Center for Radiation Oncology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232.
M L
ML
Freeman
E
E
Sierra-Rivera
G J
GJ
Voorhees
D R
DR
Eisert
M J
MJ
Meredith
D019328:Buthionine Sulfoximine; D002330:Carmustine / Q000494:pharmacology; D002478:Cells, Cultured; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D005978:Glutathione / Q000172:deficiency* / Q000187:drug effects; D006360:Heat-Shock Proteins / Q000096:biosynthesis*; D006358:Hot Temperature; D006801:Humans; D008717:Methionine Sulfoximine / Q000031:analogs & derivatives / Q000494:pharmacology; D010084:Oxidation-Reduction; D012333:RNA, Messenger / Q000096:biosynthesis
D006360:Heat-Shock Proteins; D012333:RNA, Messenger; D008717:Methionine Sulfoximine; D019328:Buthionine Sulfoximine; D005978:Glutathione; D002330:Carmustine; D004121:Dimethyl Sulfoxide