MIRA-SNuPE, a quantitative, multiplex method for measuring allele-specific DNA methylation

Area of Science:

• Epigenetics
• Molecular Biology
• Genetics

Background:

• 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) are crucial epigenetic marks involved in gene regulation.
• Standard methods like bisulfite sequencing cannot differentiate between 5mC and 5hmC.
• Allele-specific methylation is vital for genomic imprinting and other regulatory processes.

Purpose of the Study:

• To develop and validate a method for specifically detecting 5-methylcytosine (5mC) at allele-specific differentially methylated regions (DMRs).
• To analyze DNA methylation patterns in imprinted genes and identify variations in different tissues.
• To assess the utility of the developed assay for studying imprinting disorders and haplotype-associated methylation.

Main Methods:

• Methylated CpG island recovery assay (MIRA) was employed for specific detection of 5mC.
• MIRA was combined with multiplex single nucleotide primer extension (SNuPE) assays for allele-specific analysis.
• The MIRA-SNuPE assay was applied to mouse embryo fibroblasts (MEFs) and various placental and embryonic tissues.

Main Results:

• MIRA specifically detected 5mC, distinguishing it from 5hmC.
• The MIRA-SNuPE assay successfully identified allele-specific methylation at imprinted DMRs in normal and aberrant methylation cases.
• Placenta showed less DNA methylation bias at DMRs compared to other tested tissues like yolk sac, amnion, brain, heart, kidney, liver, and muscle.

Conclusions:

• The MIRA-SNuPE assay is a robust method for analyzing allele-specific CpG methylation, particularly at DMRs.
• This technique can accurately detect aberrant methylation patterns, such as loss-of-imprinting.
• The findings provide insights into tissue-specific DNA methylation patterns and offer a valuable tool for studying imprinting, X-chromosome inactivation, and population methylation differences.