The transcription of the XRCC1 gene in spleen following ionizing irradiation in radiosensitive and radioresistant mice

The XRCC1 gene was described to play a role for the sensitivity of mammalian cell lines towards ionizing irradiation. Cells with a mutation of this gene present with decreased single strand break repair, reduced recombination repair, show increased double strand breaks and sister chromatid exchange is increased up to tenfold. The goal of our study was to investigate the transcription of this gene in the spleen following ionizing irradiation in the mouse. Furthermore, we intended to examine whether radiation sensitive (RS) mice would show a transcriptional pattern different from radiation resistant (RR) mice. Radiation sensitive BALB/c/J Him mice and radiation resistant C3H He/Him mice were untreated or whole body irradiated with X-ray at 4 and 6 Gy and sacrificed 5, 15 and 30 min after irradiation. mRNA was isolated from the spleen and hybridized with probes for XRCC1 and beta-actin as a house keeping gene control. Transcription of XRCC1 was not different in unirradiated or 4 Gyirradiated mouse RR or RS mouse strains. When irradiated at 6 Gy, RR mice showed an approximately threefold increase of mRNA XRCC1/mRNA beta actin as early as 15 min after irradiation. We conclude that radiation resistant mice show a higher transcription level for the XRCC1 gene in the spleen early after high dose X-ray whole body irradiation. This finding is the first in vivo study on XRCC1 of this kind and may in part explain the differences in the radiation sensitivity between the two strains studied.