Combined effects of ionizing radiation and cycloheximide on gene expression.
We performed experiments to determine the effects of ionizing radiation exposure on expression of genes such as beta-actin, c-fos, histone H4, c-myc, c-jun, Rb, and p53 after exposure of Syrian hamster embryo (SHE) cells to the protein synthesis inhibitor cycloheximide. The purpose of these experiments was to determine the role of a labile protein in the radiation-induced response. The results revealed that when ionizing radiation (either fission-spectrum neutrons or gamma rays) was administered 15 min after cycloheximide treatment of SHE cells, the radiation exposure reduced cycloheximide-mediated gene induction of c-fos, histone H4, and c-jun. In addition, dose-rate differences were found when radiation exposure most significantly inhibited the cycloheximide response. Our results suggest that ionizing radiation does not act as a general protein-synthesis inhibitor and that the presence of a labile protein is required for the maintenance of specific gene transcription and mRNA accumulation after radiation exposure, especially at high dose-rates.
Woloschak
G E
GE
Center for Mechanistic Biology and Biotechnology, Argonne National Laboratory, IL 60439-4833, USA.
Felcher
P
P
Chang-Liu
C M
CM
D000199:Actins / Q000235:genetics; D000818:Animals; D002478:Cells, Cultured; D006224:Cricetinae; D003513:Cycloheximide / Q000494:pharmacology*; D004622:Embryo, Mammalian; D005720:Gamma Rays; D015870:Gene Expression / Q000187:drug effects* / Q000528:radiation effects*; D005786:Gene Expression Regulation / Q000187:drug effects* / Q000528:radiation effects*; D006657:Histones / Q000235:genetics; D018499:Linear Energy Transfer; D008647:Mesocricetus; D011519:Proto-Oncogenes / Q000187:drug effects / Q000528:radiation effects; D012313:RNA / Q000032:analysis / Q000187:drug effects / Q000528:radiation effects; D014158:Transcription, Genetic / Q000187:drug effects / Q000528:radiation effects; D015533:Transcriptional Activation
D000199:Actins; D006657:Histones; D012313:RNA; D003513:Cycloheximide