Relation of sperm protamine transcripts content with global DNA methylation and DNA methyltransferases mRNA in men with severe sperm abnormalities

Background: This study aims at evaluating the relation of mRNA expression of DNA methyltransferases (DNMTs) like DNMT1, DNMT3A and DNMT3B mRNA and sperm global DNA methylation with protamine transcripts content in men with severe sperm abnormalities.Materials and Methods: Each semen sample was isolated and purified using a standard gradient isolation procedure issued by the WHO by layering 1 mL of 40% (v/v) density gradient mediume over 1 mL of 80% (v/v). The number of 30 oligoasthenoteratozoospermic patients (OAT) and 30 cases of normozoospermia as control were compared using real-time quantitative reverse transcriptase polymerase chain reaction for mRNA expression of DNMT1, 3A, 3B, protamine1 (P1) and protamine2 (P2). The enzyme-linked immunosorbent assay was used to detect sperm global DNA methylation. p<0.05 was considered statistically significant.Results: The mRNA expression of P1, P2 and P1plus P2 as the total protamine transcripts was significantly higher in OAT. However, the P1 to P2 mRNA as the protamine ratio was lower in OAT (0.27) compared to control group (0.51) which was significantly different (p<0.04). The median of global DNA methylation was (3.1%) in OAT and (2.0%) in control group to a significant difference (p<0.001). The mRNA expression of DNMT1 was not statistically different in two groups. The mRNA expression of DNMT3A and DNMT3B were higher in OAT compared to that in control group to a significant difference (p=0.04, p=0.03 respectively) .In OAT neither of protamine content of total nor ratio was related to sperm parameters. However, in control group P1plus P2 mRNA was negatively correlated to sperm progressive motility at a significant level.Conclusion: In OAT, the increasing level of DNMT3A, 3B mRNA, sperm global methylation, P1plus P2 mRNA and decreasing of P1 to P2 ratio were significantly seen. In OAT, the content of protamine transcript was not correlated with sperm parameters.

Keywords:

Sperm , DNA , Transcription