Inhibition of protein synthesis and heat protection: histidinol-resistant mutant cell lines.
The mechanism of histidinol (HST)-induced heat protection was investigated to test the hypothesis that the cessation of protein synthesis itself is one of the events involved in heat protection. For this study, we isolated three HST-resistant mutant strains. HST (5 mM), which inhibited protein synthesis by 88% in the wild type, caused only 0, 9, and 25% inhibition in three mutants, respectively. The drug, which afforded heat protection, (i.e., a 125-fold increase in survival from 4 x 10(-3) to 5 x 10(-1) after 2 hr at 43 degrees C in wild type), did not protect mutant cells from heat killing. In contrast, cycloheximide (10 micrograms/ml) which inhibited protein synthesis by 95% in both wild type and mutant cell types, protected both cell types from heat killing. Therefore, these results suggest that the cessation of protein synthesis, per se, preventing synthesis of nascent polypeptides, is a major event leading to heat protection.
Lee
Y J
YJ
Department of Radiation Oncology, William Beaumont Hospital, Royal Oak, Michigan 48073.
Hou
Z Z
ZZ
Kim
D
D
al-Saadi
A
A
Corry
P M
PM
D000818:Animals; D001692:Biological Transport; D016466:CHO Cells; D002470:Cell Survival / Q000187:drug effects; D002999:Clone Cells; D006224:Cricetinae; D003513:Cycloheximide / Q000494:pharmacology*; D004351:Drug Resistance; D005020:Ethyl Methanesulfonate / Q000494:pharmacology; D006641:Histidinol / Q000378:metabolism / Q000494:pharmacology*; D006358:Hot Temperature; D007700:Kinetics; D016296:Mutagenesis; D014176:Protein Biosynthesis
D006641:Histidinol; D003513:Cycloheximide; D005020:Ethyl Methanesulfonate