Transcription factor-recognition sequences potentially involved in modulation of gene expression after exposure to low-dose-rate γ-rays in the mouse liver

In vivo modulation of gene expression profiles after low-dose and low-dose-rate irradiation has been observed in a variety of experimental systems. however,few studies actually investigated the underlying mechanisms for these genetic responses. in this study,we used pre-existing microarray data and searched for gene modulations in response to long-term,low-dose-rate irradiation. nucleotide sequences in the neighboring region of the up-regulated,down-regulated,and unaffected genes were retrieved from the entrez gene database,and recognition sequences for transcription factors (tfs) were searched using the tfsearch database. as a result,we suggested 21 potential tf-binding sites with significantly different incidence between the three gene groups (up-regulated,down-regulated and unaffected gene groups). the binding sites for sterol regulatory element-binding protein 1 (srebp-1),aryl hydrocarbon receptor (ahr/ar) and olfactory 1 (olf-1) were suggested to be involved in up-regulation,while the binding sites for glucocorticoid receptor (gr(ggtacaannt gtyctk)) and hepatocyte nuclear factor 1 (hnf-1) were suggested to be involved in down-regulation of the genes. in addition,the binding sites for activating enhancer-binding protein 4 (ap-4),nuclear factor-κb (nfκb),gr (nnnnnncnntntgtnctnn) and early growth response 3 (egr-3) were correlated with modulation of gene expression regardless of the direction of modulation. our results suggest that these tf-binding sites are involved in gene modulations after long-term continuous irradiation with low-dose-rate γ rays. gr and/or srebp-1 might be associated with the altered metabolic process observed in liver after exposure to low-dose-rate irradiation.