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Differential DNA methylation alterations in radiation-sensitive and -resistant cells
M Ahmad Chaudhry1, Romaica A Omaruddin
1Department of Medical Laboratory and Radiation Sciences, University of Vermont, Burlington, Vermont 05405, USA. mchaudhr@uvm.edu
DNA and Cell Biology
|December 22, 2011
Summary
Ionizing radiation exposure causes epigenetic changes in DNA methylation patterns. These dynamic changes in methylation are cell-type dependent and involve key enzymes, impacting cellular responses to radiation.
Area of Science:
- Epigenetics
- Radiation Biology
- Genomics
Background:
- Understanding cellular responses to ionizing radiation (IR) is crucial for radiotherapy and health risk assessment.
- Epigenetic modifications, particularly DNA methylation, are increasingly recognized as regulators of cellular responses to IR.
- DNA methylation involves converting cytosine bases to 5-methyl cytosine in CpG dimers, influencing various biological processes.
Purpose of the Study:
- To investigate DNA methylation changes in response to IR in human cell lines with differing sensitivities (TK6 and WTK1).
- To analyze the dynamic alterations in regional genomic DNA methylation patterns and their time-dependency.
- To examine the modulation of DNA methylation machinery components in irradiated cells.
Main Methods:
- Global DNA methylation analysis using an enzyme-linked immunosorbent assay (ELISA)-based assay.
- Regional genomic DNA methylation profiling via arbitrarily primed polymerase chain reaction (AP-PCR).
- Quantitative analysis of DNA methyltransferase (DNMT) and TET enzyme mRNA levels via RT-qPCR.
Main Results:
- Both cell lines exhibited global DNA hypomethylation after IR exposure.
- AP-PCR revealed time-dependent, dynamic changes in regional DNA methylation patterns, with distinct profiles between TK6 and WTK1 cells.
- Irradiation modulated DNA methylation machinery: DNMT1 mRNA increased in TK6 but decreased in WTK1; DNMT3A, DNMT3B, and TET1 were induced in both cell types.
Conclusions:
- Irradiated cells undergo epigenetic alterations in DNA methylation patterns, with the associated machinery playing a role in the radiation response.
- DNA methylation changes are dynamic, region-specific, and influenced by the time post-irradiation and the cell's genetic background.
- These findings highlight the complex interplay between DNA methylation and cellular responses to ionizing radiation, with implications for radiotherapy and radiation protection.
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