Gene expression profiles in mouse liver after long-term low-dose-rate irradiation with gamma rays.
Changes in gene expression profiles in mouse liver induced by long-term low-dose-rate γ irradiation were examined by microarray analysis. Three groups of male C57BL/6J mice were exposed to whole-body radiation at dose rates of 17-20 mGy/day, 0.86-1.0 mGy/day or 0.042-0.050 mGy/day for 401-485 days with cumulative doses of approximately 8 Gy, 0.4 Gy or 0.02 Gy, respectively. The gene expression levels in the livers of six animals from each exposure group were compared individually with that of pooled sham-irradiated animals. Some genes revealed a large variation in expression levels among individuals within each group, and the number of genes showing common changes in individuals from each group was limited: 20 and 11 genes showed more than 1.5-fold modulation with 17-20 mGy/day and 0.86-1.0 mGy/day, respectively. Three genes showed more than 1.5-fold modulation even at the lowest dose-rate of 0.04-0.05 mGy/day. Most of these genes were down-regulated. RT-PCR analysis confirmed the expression profiles of the majority of these genes. The results indicate that a few genes are modulated in response to very low-dose-rate irradiation. The functional analysis suggests that these genes may influence many processes, including obesity and tumorigenesis.
Uehara
Yoshihiko
Y
Department of Cell Biology, Graduate School of Medicine, Tohoku University, Sendai 980-8575, Japan. yuehara@mail.tains.tohoku.ac.jp
Ito
Yasuko
Y
Taki
Keiko
K
Nenoi
Mitsuru
M
Ichinohe
Kazuaki
K
Nakamura
Shingo
S
Tanaka
Satoshi
S
Oghiso
Yoichi
Y
Tanaka
Kimio
K
Matsumoto
Tsuneya
T
Paunesku
Tatjana
T
Woloschak
Gayle E
GE
Ono
Tetsuya
T
D000818:Animals; D004307:Dose-Response Relationship, Radiation; D005720:Gamma Rays; D020869:Gene Expression Profiling; D008099:Liver / Q000378:metabolism* / Q000528:radiation effects*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D016273:Occupational Exposure / Q000009:adverse effects; D020411:Oligonucleotide Array Sequence Analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors