Expression of cytoskeletal elements in proliferating cells following radiation exposure.
Previous work has demonstrated that radiation exposure modulates the expression of a series of genes, including those that encode cytoskeletal elements. The experiments reported here were designed to examine (1) the comparative effects of neutrons administered at high versus low dose-rates, (2) the comparative effects of neutrons on cycling versus resting cells and (3) the comparative effects of neutrons versus gamma-rays on beta- and gamma-actin mRNA accumulation in Syrian hamster embryo (SHE) cells 1 and 3 h post-irradiation. JANUS fission-spectrum neutrons from Argonne National Laboratory's JANUS reactor administered at high (12 cGy/min) dose-rates had little effect on resting cells, but at very low dose-rates (0.1 cGy/min) had a repressive effect on gamma-actin mRNA accumulation. Increased accumulation of beta-actin mRNA was detected following the exposure of cells to neutrons administered at high dose-rates, but repression of beta-actin mRNA was observed when neutrons were administered at low dose-rates. Cycling cells (unexposed and neutron irradiated) in all cases expressed higher levels of all actin-specific mRNAs than resting cells; beta-actin mRNA (but not gamma-actin mRNA) was induced to a greater extent in cycling cells than in resting cells during the first hour following neutron exposure. In resting cells, however, low dose-rate neutrons were more effective than low dose-rate gamma-rays at repressing both gamma- and beta-actin mRNA accumulation. These results demonstrate the differential effects of radiation quality (neutrons versus gamma-rays) and cell-cycle state on the modulation of actin isotype-specific gene expression.
Woloschak
G E
GE
Biological and Medical Research Division, BIM-202, Argonne National Laboratory, IL 60439.
Chang-Liu
C M
CM
D000199:Actins / Q000378:metabolism; D000818:Animals; D002455:Cell Division; D003599:Cytoskeleton / Q000528:radiation effects*; D005720:Gamma Rays; D015870:Gene Expression / Q000528:radiation effects*; D066298:In Vitro Techniques; D009502:Neutrons; D012333:RNA, Messenger / Q000378:metabolism; D011829:Radiation Dosage
D000199:Actins; D012333:RNA, Messenger