Transcriptional responses to ionizing radiation reveal that p53R2 protects against radiation-induced mutagenesis in human lymphoblastoid cells
Journal
Oncogene
Journal Issue
25
4
Pages
622-632
Date Issued
2006
Date
2006
Author(s)
Chen, X.
Chandramouli, G. V. R.
Chen, Y.
Yan, H.
Zhao, S.
Keng, P.
Liber, H. L.
Coleman, C. N.
Mitchell, J. B.
Abstract
The p53 protein has been implicated in multiple cellular responses related to DNA damage. Alterations in any of these cellular responses could be related to increased genomic instability. Our previous study has shown that mutations in p53 lead to hypermutability to ionizing radiation. To investigate further how p53 is involved in regulating mutational processes, we used 8K cDNA microarrays to compare the patterns of gene expression among three closely related human cell lines with different p53 status including TK6 (wild-type p53), NH32 (p53-null), and WTK1 (mutant p53). Total RNA samples were collected at 1, 3, 6, 9, and 24 h after 10 Gy γ-irradiation. Template-based clustering analysis of the gene expression over the time course showed that 464 genes are either up or downregulated by at least twofold following radiation treatment. In addition, cluster analyses of gene expression profiles among these three cell lines revealed distinct patterns. In TK6, 165 genes were upregulated, while 36 genes were downregulated. In contrast, in WTK1 75 genes were upregulated and 12 genes were downregulated. In NH32, only 54 genes were upregulated. Furthermore, we found several genes associated with DNA repair namely p53R2, DDB2, XPC, PCNA, BTG2, and MSH2 that were highly induced in TK6 compared to WTK1 and NH32. p53R2, which is regulated by the tumor suppressor p53, is a small subunit of ribonucleotide reductase. To determine whether it is involved in radiation-induced mutagenesis, p53R2 protein was inhibited by siRNA in TK6 cells and followed by 2 Gy radiation. The background mutation frequencies at the TK locus of siRNA-transfected TK6 cells were about three times higher than those seen in TK6 cells. The mutation frequencies of siRNA-transfected TK6 cells after 2 Gy radiation were significantly higher than the irradiated TK6 cells without p53R2 knock down. These results indicate that p53R2 was induced by p53 protein and is involved in protecting against radiation-induced mutagenesis. © 2006 Nature Publishing Group All rights reserved.
Subjects
Microarray; p53R2; Radiation; TK6
SDGs
Other Subjects
complementary DNA; protein p53; protein p5r2; protein subunit; ribonucleotide reductase; small interfering RNA; unclassified drug; article; cell protection; controlled study; DNA microarray; DNA repair; down regulation; gamma radiation; gene cluster; gene expression profiling; gene function; gene induction; gene locus; genetic transfection; human; human cell; ionizing radiation; knockout gene; lymphoblastoid cell; mutagenesis; priority journal; protein analysis; protein function; radiation dose; RNA analysis; transcription regulation; upregulation; wild type; Cells, Cultured; DNA Damage; DNA Repair; Gene Expression; Gene Expression Profiling; Humans; Mutation; NF-kappa B; Transcription, Genetic; Transforming Growth Factor beta; Transforming Growth Factor beta1; Tumor Suppressor Protein p53
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