Differences in thermotolerance induced by heat or sodium arsenite: correlation between redistribution of a 26-kDa protein and development of protein synthesis-independent thermotolerance in CHO cells.
In previous studies, we have demonstrated the differences in thermotolerance induced by heat and sodium arsenite (Lee et al., Radiat. Res. 121, 295-303, 1990). In this study, we investigated whether a 26-kDa protein might play an important role in evincing these differences. Chinese hamster ovary (CHO) cells treated for either 1 h with 100 microM sodium arsenite (ARS) or 10 min at 45.5 degrees C became thermotolerant to a test heat treatment at 43 degrees C administered 6 or 12 h later, respectively. After the test heating at 43 degrees C for 1.5 h, the level of 26-kDa protein in the nucleus was decreased by 92% in nonthermotolerant cells, 78% in ARS-induced thermotolerant cells, and 3% in heat-induced thermotolerant cells. Inhibiting protein synthesis with cycloheximide (CHM, 10 micrograms/ml) after ARS treatment eliminated thermotolerance to 43 degrees C and delayed restoration of the 26-kDa protein in the nucleus. In contrast, CHM neither prevented the development of thermotolerance nor inhibited the restoration of the 26-kDa protein in heat-induced thermotolerant cells. However, when cells were exposed to cold (4 degrees C), immediately after initial heating, restoration of the 26-kDa protein and development of thermotolerance did not occur. These results demonstrate a good correlation between the restoration and/or the presence of this 26-kDa protein and the development of protein synthesis-independent thermotolerance.
Lee
Y J
YJ
Department of Radiation Oncology, William Beaumont Hospital, Royal Oak, Michigan 48073.
Kim
D H
DH
Hou
Z Z
ZZ
Corry
P M
PM
D000064:Acclimatization / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D001151:Arsenic / Q000494:pharmacology*; D018053:Arsenites; D002467:Cell Nucleus / Q000187:drug effects* / Q000378:metabolism; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D006360:Heat-Shock Proteins / Q000096:biosynthesis / Q000378:metabolism*; D006358:Hot Temperature; D017670:Sodium Compounds
D018053:Arsenites; D006360:Heat-Shock Proteins; D017670:Sodium Compounds; C017947:sodium arsenite; D003513:Cycloheximide; D001151:Arsenic