Epigenetic silencing of bovine meiosis-specific recombinase Dmc1 by DNA methylation

The meiosis-specific recombinase Dmc1 is a member of the Rad51 family that is required for the pairing of homologous chromosomes, formation of crossovers and recombination during meiosis. However, the molecular mechanisms of Dmc1 in cattle spermatogenesis remain unclear. In this study, we measured the methylation status of bDmc1 promoter by bisulfite sequencing, and the results showed that the methylation level of -2012CpG site in bDmc1 promoter was higher in the testes of cattle-yak hybrids (30%, 3/10) with male sterility compared with cattle (0%, 0/10). Moreover, the cattle bDmc1 promoter especially -2012CpG site was highly methylated in bovine mammary epithelial cells (BMECs) in which bDmc1 was low-expressed. Luciferase assays revealed that the promoter activity of bDmc1 was decreased significantly after M.SssI methylase treatment. Real-time PCR showed that bDmc1 transcription was dramatically induced in BMECs after treatment with 5-Aza-CdR. Interestingly, the differentially methylated site -2012CpG was located in the binding site for HSF by bioinformatics predictions. Taken together, these results suggest that the expression of bDmc1 was regulated by its promoter methylation and provide new insight into the molecular mechanism of Dmc1 in bovine spermatogenesis.