Methylation-sensitive restriction enzyme nested real time PCR, a potential approach for sperm DNA identification

Area of Science:

• Epigenetics
• Genomic imprinting
• Molecular biology

Background:

• The H19 gene is an imprinted gene with paternal allele silencing regulated by DNA methylation at its imprinting control region (ICR).
• This methylation pattern is reset in the germline, leading to biallelic methylation in mature sperm, unlike somatic cells.
• Understanding H19 ICR methylation in human germline is crucial, though primarily studied in mice.

Purpose of the Study:

• To investigate and quantify DNA methylation levels at the H19 ICR in human sperm and somatic cells.
• To develop and validate a methylation-sensitive restriction enzyme nested quantitative PCR (MSRE-nested-qPCR) method for assessing H19 ICR methylation.
• To determine if H19 ICR methylation patterns can distinguish sperm DNA.

Main Methods:

• Utilized methylation-sensitive restriction enzyme (HhaI) digestion followed by nested quantitative PCR (qPCR).
• Amplified H19 ICR DNA using outer primers targeting four HhaI sites.
• Quantified DNA methylation levels by real-time PCR using amplified products as templates.

Main Results:

• Somatic cells (blood samples) showed a DNA methylation level of 55.27 ± 8.36% at the H19 ICR.
• Semen samples exhibited a significantly higher DNA methylation level of 101.94 ± 11.66% at the H19 ICR.
• A threshold of 78.62% H19 ICR methylation was identified to potentially identify sperm DNA.

Conclusions:

• The MSRE-nested-qPCR method effectively quantifies H19 ICR DNA methylation levels in human samples.
• Significant differences in H19 ICR methylation exist between human somatic cells and sperm.
• The distinct methylation profile suggests potential for identifying sperm DNA based on H19 ICR methylation levels.