DNA damage caused by UV-A irradiation induces genetic instability

UV-A照射で生じたDNA損傷は遺伝的不安定性を引き起こす

漆原 あゆみ; 児玉 靖司*; 横谷 明徳

Urushibara, Ayumi; Kodama, Seiji*; Yokoya, Akinari

It is well known that ionizing radiation induces genetic instability in the progeny of irradiated cells. Since it seems unlikely that DNA double-strand breaks (DSBs) persist through several cycles of cell division, we hypothesize that some DNA lesions, but not DSBs per se, are also involved in inducing genetic instability. To find out whether genetic instability is induced by non-DSBs type of damage, particularly oxidative base lesions, we transferred a human chromosome exposed to UV-A into unirradiated mouse recipient cells by microcell fusion, and examined chromosome aberrations of the transferred human chromosome and recipient mouse chromosomes. The transferred chromosomes were analyzed by the whole chromosome painting fluorescence in situ hybridization. Most of the microcell hybrids transferred with the unirradiated human chromosomes remained diploid, and both the transferred human chromosome and recipient mouse chromosomes were stable. In contrast, the microcell hybrids transferred with the UV-A irradiated human chromosome became polyploid and structural aberrations occurred not only in the UV-A irradiated human chromosome but also in the unirradiated mouse chromosomes. These results suggest that non-DSBs type of DNA damage induced by UV-A irradiation disturbs the homeostatic maintenance of the chromosomes and induces genetic instability.