DNA methyltransferase inhibitors modulate histone methylation: epigenetic crosstalk between H3K4me3 and DNA methylation during sperm differentiation

The process of cytodifferentiation in spermatogenesis is governed by a unique genetic and molecular programme. In this context, accurate 'tuning' of the regulatory mechanisms involved in germ cells differentiation is required, as any error could have dramatic consequences on species survival and maintenance. To study the processes that govern the spatial-temporal expression of genes, as well as analyse transmission of epigenetic information to descendants, an integrated approach of genetics, biochemistry and cytology data is necessary. As information in the literature on interplay between DNA methylation and histone H3 lysine 4 trimethylation (H3K4me3) in the advanced stages of murine spermatogenesis is still scarce, we investigated the effect of a DNA methyltransferase inhibitor, 5-aza-2'-deoxycytidine, at the cytological level using immunocytochemistry methodology. Our results revealed a particular distribution of H3K4me3 during sperm cell differentiation and highlighted an important role for regulation of DNA methylation in controlling histone methylation and chromatin remodelling during spermatogenesis.