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Published on: September 7, 2017
Evidence for non-CpG methylation in mammals
Jie Yan1, Juleen R Zierath, Romain Barrès
1Section of Integrative Physiology, Department of Molecular Medicine and Surgery, Karolinska University Hospital, Karolinska Institutet, Stockholm, Sweden.
Experimental Cell Research
|September 20, 2011
Summary
Non-CpG methylation, a controversial epigenetic modification, is confirmed in mammals. This study reveals substantial levels of non-CpG methylation in various rodent and human tissues.
Area of Science:
- Epigenetics
- Molecular Biology
- Genomics
Background:
- The role and extent of cytosine methylation on non-CpG sequences in mammals remain debated.
- Previous studies may have underestimated non-CpG methylation due to technical limitations.
Purpose of the Study:
- To accurately quantify global non-CpG methylation levels in mammalian tissues.
- To investigate potential reasons for the underestimation of non-CpG methylation.
Main Methods:
- Adaptation and application of a LuminoMetric-based Assay (LUMA) for global non-CpG methylation analysis.
- Bisulfite sequencing of DNA from human, rat, and mouse tissues.
- Comparative analysis of methylation levels with and without a secondary PCR step.
Main Results:
- Significant levels of non-CpG methylation were detected in mouse tissues (7-13%) and human/rodent tissues (up to 7.5%).
- A secondary PCR step before bisulfite sequencing reduced observed non-CpG methylation to 1.5%, explaining prior underestimations.
- 3T3-L1 fibroblasts showed minimal non-CpG methylation (<1%).
Conclusions:
- Non-CpG methylation occurs at substantial levels in various mammalian tissues.
- Technical factors, particularly PCR amplification, can lead to the underestimation of true non-CpG methylation levels.
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