Host: The Japan Radiation Research Society, Chairman of the 52nd Annual Meeting, Toshiteru Okubo (Radiation Effects Research Foundation)
Artemis, which is originally discovered as a responsible gene for human radiation-sensitive severe combined immunodeficiency syndrome, is a nuclease required for V(D)J recombination as well as repair of the nonhomologous end-joining pathway of DNA double-strand breaks (DSB) introduced by ionizing radiation (IR).
Artemis cleaves DNA hairpin intermediate during V(D)J recombination, while the precise function and its regulation of Artemis during DSB repair is not well understood.
It is well known that Artemis is phosphorylated at multiple sites by DNA-PKcs and ATM after IR. However, Artemis mutations in these phosphorylation sites only marginally affect their nuclease activities in vitro, and the mutants still complements IR sensitivities and V(D)J recombination defects in Artemis-deficient cells.
We examined nuclear dynamics of human Artemis-GFP fusion protein expressed in human fibroblast cells using laser UVA microirradiation system. We observed the accumulation of Artemis-GFP at damage sites after microirradiation in live cells. By mutational analysis, it has been shown that this accumulation depends on the multiple phosphorylation sites, but not on the nuclease domain. Collectively, these findings suggest that the dynamics of Artemis after IR is regulated by phsphorylation.
