The profiles of gamma-H2AX along with ATM/DNA-PKcs activation in the lymphocytes and granulocytes of rat and human blood exposed to gamma rays.
Establishing a rat model suitable for γ-H2AX biodosimeter studies has important implications for dose assessment of internal radionuclide contamination in humans. In this study, γ-H2AX, p-ATM and p-DNA-PKcs foci were enumerated using immunocytofluorescence method, and their protein levels were measured by Western blot in rat blood lymphocytes and granulocytes exposed to γ-rays compared with human blood lymphocytes and granulocytes. It was found that DNA double-strand break repair kinetics and linear dose responses in rat lymphocytes were similar to those observed in the human counterparts. Moreover, radiation induced clear p-ATM and p-DNA-PKcs foci formation and an increase in ratio of co-localization of p-ATM or p-DNA-PKcs with γ-H2AX foci in rat lymphocytes similar to those of human lymphocytes. The level of γ-H2AX protein in irradiated rat and human lymphocytes was significantly reduced by inhibitors of ATM and DNA-PKcs. Surprisingly, unlike human granulocytes, rat granulocytes with DNA-PKcs deficiency displayed a rapid accumulation, but delayed disappearance of γ-H2AX foci with essentially no change from 10 h to 48 h post-irradiation. Furthermore, inhibition of ATM activity in rat granulocytes also decreased radiation-induced γ-H2AX foci formation. In comparison, human granulocytes showed no response to irradiation regarding γ-H2AX, p-ATM or p-DNA-PKcs foci. Importantly, incidence of γ-H2AX foci in lymphocytes after total-body radiation of rats was consistent with that of in vitro irradiation of rat lymphocytes. These findings show that rats are a useful in vivo model for validation of γ-H2AX biodosimetry for dose assessment in humans. ATM and DNA-PKcs participate together in DSB repair in rat lymphocytes similar to that of human lymphocytes. Further, rat granulocytes, which have the characteristic of delayed disappearance of γ-H2AX foci in response to radiation, may be a useful experimental system for biodosimetry studies.
Department of Radiation Biology, Institute of Radiation Medicine, Fudan University, No. 2094, Xie-Tu Road, Shanghai, 200032, People's Republic of China.
Jing
J
Wang
Department of Radiation Biology, Institute of Radiation Medicine, Fudan University, No. 2094, Xie-Tu Road, Shanghai, 200032, People's Republic of China.
Lina
L
Yin
Department of Radiation Biology, Institute of Radiation Medicine, Fudan University, No. 2094, Xie-Tu Road, Shanghai, 200032, People's Republic of China.
Junxiang
J
Zhang
Department of Radiation Biology, Institute of Radiation Medicine, Fudan University, No. 2094, Xie-Tu Road, Shanghai, 200032, People's Republic of China.
Yaping
Y
Zhang
Department of Radiation Biology, Institute of Radiation Medicine, Fudan University, No. 2094, Xie-Tu Road, Shanghai, 200032, People's Republic of China.
Xuxia
X
Zhang
Department of Radiation Biology, Institute of Radiation Medicine, Fudan University, No. 2094, Xie-Tu Road, Shanghai, 200032, People's Republic of China.
Defang
D
Ding
Department of Radiation Biology, Institute of Radiation Medicine, Fudan University, No. 2094, Xie-Tu Road, Shanghai, 200032, People's Republic of China.
Yun
Y
Gao
Department of Radiation Biology, Institute of Radiation Medicine, Fudan University, No. 2094, Xie-Tu Road, Shanghai, 200032, People's Republic of China.
Qiang
Q
Li
Department of Radiation Biology, Institute of Radiation Medicine, Fudan University, No. 2094, Xie-Tu Road, Shanghai, 200032, People's Republic of China. hhchen@shmu.edu.cn.
Honghong
H
Chen
D000818:Animals; D064007:Ataxia Telangiectasia Mutated Proteins / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D053903:DNA Breaks, Double-Stranded; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005720:Gamma Rays; D006098:Granulocytes / Q000378:metabolism / Q000528:radiation effects*; D006657:Histones / Q000378:metabolism*; D006801:Humans; D008214:Lymphocytes / Q000378:metabolism / Q000528:radiation effects*; D008297:Male; D011829:Radiation Dosage; D011834:Radiation Monitoring / Q000379:methods; D017207:Rats, Sprague-Dawley
C109198:CIB1 protein, human; D002135:Calcium-Binding Proteins; C468783:H2AX protein, human; D006657:Histones; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins
Granulocytes; Lymphocytes; Phospho-ATM foci; Phospho-DNA-PKcs foci; γ-H2AX foci; γ-Ray