EUROPEAN RADIATION RESEARCH 2012

The potential impact of low dose ionizing γ-radiation on Ikaros-mediated immune activation in B lymphoblasts

18 Oct 2012, 16:49

1m

Poster Hall (Vietri sul Mare)

poster preferred Modulation of Radiosensitivity Poster Session 3

Speaker

Dr Kwang Hee Yang (Korea Hydro & Nuclear Power co. LTD.)

Description

The biological effects of low dose ionizing radiation (LDIR) remain insufficiently understood. In our previous study, Ikaros was phosphorylated in response to LDIR in IM-9 B lymphoblasts cell line. Ikaros encodes a zinc finger transcription factor that is an important regulator of a hematopoietic stem cells (HSCs) progression in the B lymphoid lineage development, differentiation and proliferation. This study showed the biological effects of LDIR in radiation-sensitive immune cells. We observed that almost 20% of cell proliferation was enhanced by LDIR (0.05 Gy) in IM-9 B lymphocytes. We found that the phosphorylation of Ikaros at Ser304 and Ser306 residues was up-regulated through CK2/AKT pathway in LDIR irradiated IM-9 B lymphocytes, decreasing its DNA binding activity. We also revealed that Ikaros protein was translocated from the nucleus to the cytoplasm after LDIR irradiation, and then binded with Autotaxin (ENPP2, ATX) protein. In addition, we found that the lysoPLD activity of ATX was increased by the interaction between Ikaros and ATX protein. The lysoPLD activity of ATX converts lysophosphatidylcholine (LPC) into lysophosphatidic acid (LPA) which is a bioactive phospholipid involved in proliferation, differentiation, and migration of immune cells. Taken together, these results indicate that Ikaros may be an important regulator of immune activation through the interaction with Autotaxin. Therefore, we suggest that low dose ionizing radiation can show a beneficial effect stimulating the immune activity in IM-9 B lymphoblasts.