PRAMEY enhances sperm-egg binding and modulates epigenetic dynamics in bovine embryogenesis

Infertility and subfertility are significant reproductive challenges in cattle, often linked to genetic factors. Among these genetic factors, the bovine Y-linked gene family, PRAMEY, has emerged as a candidate due to its involvement in germ cell formation, fertilization, and embryonic development. This study investigates PRAMEY's role in sperm-egg binding, acrosome integrity, and epigenetic modifications during fertilization and early embryogenesis. Using IVF with bovine spermatozoa treated with either PRAMEY antibody (ab) or rabbit IgG control, we assessed sperm-egg binding and acrosome integrity at 2, 4, and 6 h post-fertilization (hpf). PRAMEY ab treatment doubled sperm binding per oocyte across all time points, with a significant increase at 6 hpf (P ≤ 0.05), although no differences in acrosome integrity were observed (P > 0.05). To explore PRAMEY's role in epigenetic regulation, we analyzed DNA (5-methylcytosine (5-mC)) and histone (H3K9me3 and H3K27me3) methylation in zygotes and embryos using immunofluorescent staining techniques. Zygotes derived from PRAMEY ab-treated spermatozoa showed significantly reduced DNA methylation in paternal pronuclei at 10 hpf and maternal pronuclei at 25 hpf (P ≤ 0.01). Histone methylation analysis revealed no significant differences in H3K9me3 methylation between groups, but H3K27me3 methylation was significantly lower in embryos produced using PRAMEY ab-treated spermatozoa at the 8-cell and morula stages (P ≤ 0.05). In summary, PRAMEY inhibition enhances sperm-egg binding and influences DNA and histone methylation dynamics in bovine embryos, underscoring its potential role in fertilization and early embryonic epigenetic regulation.