Histone lysine methylation exhibits a distinct distribution during spermatogenesis in pigs

Spermatogenesis is a continual process throughout the adult life of a male, which is governed by unique transcriptional regulation and massive alterations of chromatin. Histone modification was one of the underlying epigenetic mechanisms during spermatogenesis. It has been shown that methylation of histone lysine exhibits a distinct distribution in mice during spermatogenesis and some histone lysine methylation is essential for male fertility. However, the dynamic change of methylated histone in porcine testis tissue was largely unknown. Here, we studied the dynamic modulation of three types of methylation (monomethylation, dimethylation, and trimethylation) of H3K4, H3K27, and H4K20 during spermatogenesis in pigs. The results showed that H3K4me2/3, H3K27me3, and H4K20me1/2/3 were extensively localized in adult pig testis. Interestingly, we found that undifferentiated spermatogonia contained strongly H4K20me2 and H4K20me3, but little H4K20me1, whereas the differentiated spermatogonia possessed H4K20me1 and H4K20me2 and little H4K20me3. The findings of this study help for the understanding of epigenetic modifications during spermatogenesis in pigs and provide information for further studies.