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Updated: Jun 28, 2026
Methodology for Accurate Detection of Mitochondrial DNA Methylation
Published on: May 20, 2018
Methyl group acceptance assay for the determination of global DNA methylation levels
Kenneth P Nephew1, Curt Balch, David G Skalnik
1Department of Cellular and Integrative Physiology, Medical Sciences Program, Indiana University School of Medicine, Bloomington, IN, USA.
Abstract:
DNA methylation levels are affected by numerous environmental influences, including diet and xenobiotic exposure, and neoplasia has been firmly associated with genomic hypomethylation and localized hypermethylation of tumor suppressor genes. To reverse methylation-induced gene repression, DNA hypomethylating agents are currently in clinical trials for various malignancies, with two of these now approved for the therapy of myelodysplastic syndrome, and the efficacy of these drugs can be assessed by the monitoring of global DNA methylation levels. Herein, we outline a simple, well-established method for the evaluation of genomic DNA methylation levels, based on the ability of isolated DNA to "accept" radiolabeled methyl groups from S-[3H-methyl] adenosylmethionine, using the bacterial CpG methyltransferase SssI. As this enzyme methylates all unmethylated CpG dinucleotides in the genome, radiolabeled methyl group acceptance is inversely proportional to the level of preexisting methylation. This assay is applicable to a number of translational and basic research questions.
Insights
This study presents a straightforward method to measure global DNA methylation levels. The assay uses a bacterial enzyme to quantify methylation, aiding in assessing cancer therapies.
Area of Science:
- Epigenetics
- Genomics
- Cancer Biology
Background:
- DNA methylation is crucial in gene regulation and is altered in cancer.
- Environmental factors like diet and xenobiotics influence DNA methylation patterns.
- Genomic hypomethylation and tumor suppressor gene hypermethylation are hallmarks of neoplasia.
Purpose of the Study:
- To describe a simple and established method for evaluating genomic DNA methylation levels.
- To provide a tool for monitoring the efficacy of DNA hypomethylating agents in cancer therapy.
- To support translational and basic research in epigenetics and oncology.
Main Methods:
- Utilizes the bacterial CpG methyltransferase SssI for DNA methylation analysis.
- Measures the "acceptance" of radiolabeled methyl groups from S-[3H-methyl]adenosylmethionine by isolated DNA.
- Relies on the principle that SssI methylates all unmethylated CpG dinucleotides.
Main Results:
- The assay provides a quantitative measure of global DNA methylation.
- Radiolabeled methyl group acceptance is inversely proportional to existing DNA methylation levels.
- The method is robust and applicable to various research contexts.
Conclusions:
- This assay offers a reliable way to assess global DNA methylation.
- It is valuable for monitoring therapeutic responses to DNA hypomethylating agents.
- The method has broad applicability in cancer research and beyond.
