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Epigenetic germline mosaicism in infertile men
Sandra Laurentino1, Jasmin Beygo2, Verena Nordhoff1
1Centre of Reproductive Medicine and Andrology, University of Muenster, 48149 Muenster, Germany.
Human Molecular Genetics
|October 23, 2014
Summary
Spermatozoa exhibit epigenetic mosaicism in DNA methylation patterns, particularly in men with abnormal sperm parameters. This heterogeneity in imprinted gene methylation may contribute to male infertility.
Area of Science:
- Reproductive Biology
- Epigenetics
- Spermatozoa Biology
Background:
- Imprinted genes are crucial for development, with their expression regulated by DNA methylation.
- Aberrant methylation of imprinted genes in sperm DNA has been linked to male infertility.
- Previous studies overlooked potential epigenetic heterogeneity within sperm populations.
Purpose of the Study:
- To investigate epigenetic heterogeneity in sperm DNA methylation of imprinted genes.
- To determine if spermatozoa constitute a homogeneous cell population regarding DNA methylation.
- To explore the relationship between DNA methylation patterns and abnormal sperm parameters.
Main Methods:
- Analysis of swim-up sperm from 45 men (19 normal, 26 abnormal parameters).
- DNA methylation of KCNQ1OT1 measured using pyrosequencing-based oligo-sperm methylation assay (OSMA).
- Deep bisulfite sequencing (DBS) used to analyze methylation of KCNQ1OT1, MEST, H19, and MEG3 at the single-cell level.
Main Results:
- OSMA revealed significantly increased DNA methylation variation of KCNQ1OT1 in men with abnormal sperm parameters.
- DBS demonstrated homogenous methylation patterns in normozoospermic samples.
- Oligoasthenozoospermic samples showed discrete sperm populations with normal or aberrant methylation patterns; aberrant H19 methylation occurred on the maternal allele.
Conclusions:
- Semen from oligoasthenozoospermic men exhibits epigenetic mosaicism.
- This mosaicism likely arises from errors in imprint erasure during spermatogenesis.
- Findings suggest a potential link between sperm DNA methylation heterogeneity and male infertility.
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