Effects of ionizing radiation on expression of genes encoding cytoskeletal elements: Kinetics and dose effects

Publisher Website
Google Scholar
Abstract
We examined the modulation in expression of genes encoding three cytoskeletal elements (β-actin, γ-actin, and α-tubulin) in Syrian hamster embryo (SHE) cells following exposure to ionizing radiations. Early-passage SHE cells were irradiated in plateau phase with various low doses (12-200 cGy) of neutrons, γ-rays, or x-rays. RNA samples were prepared from cells at different times postexposure and were analyzed for levels of specific transcripts by northern blots. The results revealed that α-tubulin was induced by both high-linear energy of transfer (LET) (neutrons) and low-LET (γ-rays and x-rays) radiations with similar kinetics. The peak in α-tubulin mRNA accumulation occurred between 1 and 3 h postexposure; for γ-actin mRNA, accumulation was similarly induced. For both γ-actin and α-tubulin, the higher the dose during the first hour postexposure (up to 200 cGy γ-rays), the greater the level of mRNA induction. In contrast, mRNA specific for β-actin showed decreased accumulation during the first hour following radiation exposure, and remained low up to 3 h postexposure. These results document the differential modulation of genes specific for cytoskeletal elements following radiation exposure. In addition, they demonstrate a decrease in the ratio of β-actin:γ-actin mRNA within the first 3 h following γ-ray exposure. These changes in mRNA accumulation are similar to those reported in some transformed cell lines and in cells treated with tumor promoters, which suggests a role for changes in actin- and tubulin-mRNA expression in radiation-mediated transformation.