O. Labudova et al., THE TRANSCRIPTION OF THE XRCC1 GENE IN THE HEART OF RADIATION-RESISTANT AND RADIATION-SENSITIVE MICE AFTER IONIZING IRRADIATION, Pediatric research, 41(3), 1997, pp. 435-439
The XRCC1 (X-Ray Repair Cross Complementing) gene was described to pla
y a role for the sensitivity of mammalian cell Lines toward ionizing i
rradiation. Cells with a mutation of this gene present with decreased
single strand break repair and reduced recombination repair, they show
increased double strand breaks, and sister chromatid exchange is incr
eased up to 10-fold. The goal of our study was to investigate the tran
scription of this gene in the heart after ionizing irradiation in the
mouse. Furthermore, we intended to examine whether radiation-sensitive
mice would show a transcriptional pattern different from radiation-re
sistant mice. Radiation-sensitive BALB/c/J Him mice and radiation-resi
stant C3H He/Him mice were whole body irradiated with x-ray at 2, 4, a
nd 6 Gy and killed 5, 15, and 30 min after irradiation, mRNA was isola
ted from the heart and hybridized with probes for XRCC1 and beta-actin
as a housekeeping gene control. Irradiation at 2 Gy showed increased
transcription of XRCC1 at 5 min in the C3H He/Him group, approached XR
CC1 transcription of BALB/c J/Him mice at 15 min, and was lower in the
latter at 30 min after irradiation. Irradiation at 4 Gy showed double
the transcription at 5 min and an about 3-fold rapid increase of mRNA
XRCC1 in the radiation-resistant group af 15 min after irradiation, r
eturning to the transcriptional level of sensitive animals at 30 min.
Irradiation at 6 Gy seemed to overwhelm the system in both groups, but
resistant mice still showed higher levels of XRCC1 transcription. We
conclude that radiation-resistant mice show a higher transcription lev
el for the XRCC1 gene in the heart early after x-ray whole body irradi
ation. This finding is the first in vivo study on XRCC1 of this kind a
nd may in part explain the differences in the radiation sensitivity be
tween the two strains studied.