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

Abstract

This study aimed to evaluate the relationship between mRNA expression of DNA methyltransferases (DNMTs) such as DNMT1, DNMT3A and DNMT3B mRNA and sperm global DNA methylation with protamine transcripts in the sperm from men with severe sperm abnormalities. Sperm from each semen sample were isolated using a standard gradient isolation procedure by layering 1 mL of 40% (v/v) density gradient medium over 1 mL of 80% (v/v). A total of 30 oligoasthenoteratozoospermic ejaculates (OAT) and 30 normozoospermic ejaculates as controls 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 global DNA methylation in sperm. A p-value of <0.05 was considered statistically significant. In OAT ejaculates, the increased level of DNMT3A, 3B mRNA, sperm global methylation, P1 plus P2 mRNA and decrease of P1–P2 ratio were significantly different. Also the content of protamine transcript was not correlated with sperm parameters. The increased total protamine transcript levels were associated with increased mRNA methyltransferases. The increase of DNMT1 may lead to an increased level of global methylation.

Keywords:

• Sperm
• DNA
• transcription
• methylation
• protamine

Acknowledgments

The authors would like to thank Mr Mehrdad Soleimani the head of the laboratories, staff of ART Research, Andrology, Stem Cell Biology Research Centre, Recurrent Abortion Study and Hormone Laboratories in Yazd Research and Clinical Centre for Infertility.

Disclosure statement

All investigators disclose no conflict of interest in this study.

Additional information

Funding

Shahid Sadoughi University of Medical Sciences funded this study as a PhD dissertation.