Principal Investigator University of Münster Muenster, Nordrhein-Westfalen, Germany
Abstract Authors: Sandra Laurentino1; Lara M. Siebert-Kuss1; Verena Dietrich2; Sara Di Persio1; Jahnavi Bhaskaran3,4,5; Martin Stehling5; Jann-Frederik Cremers6; Sarah Sandmann2; Julian Varghese2; Sabine Kliesch6; Stefan Schlatt1; Juan M. Vaquerizas3,4,5; Nina Neuhaus1
1. Centre of Reproductive Medicine and Andrology, Institute of Reproductive and Regenerative Biology, University of Münster, Münster, Germany.
2. Institute of Medical Informatics, University of Münster, Münster, Germany.
3. MRC Laboratory of Medical Sciences, London, UK
4. Institute of Clinical Sciences, Imperial College London, London, UK
5. Max Planck Institute for Molecular Biomedicine, Münster, Germany
6. Department of Clinical and Surgical Andrology, Centre of Reproductive Medicine and Andrology, University Hospital of Münster, Münster, Germany
Abstract Text: The Germline Undergoes Genome-Wide DNA Methylation Changes During Human Spermatogenesis
Sandra Laurentino1; Lara M. Siebert-Kuss1; Verena Dietrich2; Sara Di Persio1; Jahnavi Bhaskaran3,4,5; Martin Stehling5; Jann-Frederik Cremers6; Sarah Sandmann2; Julian Varghese2; Sabine Kliesch6; Stefan Schlatt1; Juan M. Vaquerizas3,4,5; Nina Neuhaus1
1. Centre of Reproductive Medicine and Andrology, Institute of Reproductive and Regenerative Biology, University of Münster, Münster, Germany.
2. Institute of Medical Informatics, University of Münster, Münster, Germany.
3. MRC Laboratory of Medical Sciences, London, UK
4. Institute of Clinical Sciences, Imperial College London, London, UK
5. Max Planck Institute for Molecular Biomedicine, Münster, Germany
6. Department of Clinical and Surgical Andrology, Centre of Reproductive Medicine and Andrology, University Hospital of Münster, Münster, Germany
Correct establishment of germline DNA methylation patterns is required for mammalian fertilisation and development. The mammalian germline undergoes two waves of genome-wide reprogramming during prenatal life. Studies in mouse and rat indicated that the male germline methylome undergoes remodelling during spermatogenesis, however it was unknown whether a comparable process takes in the human male germline. Here, we aimed at studying DNA methylation changes occurring during human spermatogenesis and evaluating whether DNA methylation patterns are disturbed in cases of male infertility. We isolated undifferentiated and differentiating spermatogonia, primary spermatocytes (4C), and spermatids (1C) from testicular biopsies from individuals with normal (n=3) and severely disturbed spermatogenesis (cryptozoospermia; n=2) by fluorescence-activated cell sorting. The methylome of each germ cell type was analysed by enzymatic methyl-sequencing (EM-seq). We found that the germline methylome underwent remodelling during spermatogenesis progression. This included a global decline in DNA methylation in primary spermatocytes followed by partial remethylation. The methylation remodelling did not affect imprinting control regions. Regions displaying differential methylation during spermatogenesis were enriched in short intersperced nuclear elements (SINEs), a type of transposable element. The remethylation of the germline genome following meiosis occurred at particular regions and resulted in a spermatid-specific methylome. These spermatid-specific hypomethylated regions were enriched at spermatid-expressed gene promoters and in binding sites for DMRT and SOX family members. The methylomes of cryptozoospermia-derived germ cells displayed significant DNA methylation changes compared to normal ones. Differentially methylated regions in germ cells from infertile men were significantly enriched in genes involved in spermatogenesis and in transposable elements. Particularly, the evolutionarily young SVA (SINE-VNTR-Alus) D and F families of transposable elements displayed lower methylation in cryptozoospermia than in normal spermatogenesis. Our data hints at a possible association between abnormal germline methylation of transposable elements and failure of male germ cells to progress beyond meiosis, resulting in male infertility, and suggests a pivotal role for DNA methylation in the regulation of spermatogenesis and germ cell-specific gene expression.
