抄録
Ionizing radiation induces genomic instability, which is transmitted through many generations after irradiation in the progeny of surviving cells. We have hypothesized that radiation-induced large deletion causes potentially unstable chromosome regions, which are involved in delayed induction of radiation-induced genomic instability. Using phosphorylation-specific antibodies against ATM and histone H2AX, whose phosphorylation is induced by DNA double strand breaks, we detected delayed induction of phosphorylated ATM and H2AX foci in the progeny of X-ray-surviving cells, which indicated delayed induction of DNA double strand breaks. Furthermore, we found delayed chromosomal instability in X chromosomes in clones which contain large deletion involving the HPRT loci. It is suggested that large deletion involving —Mb region causes unstable chromatin structure, and it results in delayed rearrangement of chromosomes involved. These findings provide the possibility that manifestation of radiation-induced genomic instability results from delayed DNA breaks, i.e., the breaks lead to delayed chromosome rearrangements, delayed cell death etc., many generations after irradiation.
