Histone methylation and acetylation in ejaculated human sperm Effects of swim up and smoking

Capsule:
This study demonstrates a decrease of global methylation and unchanged acetylation level in ejaculated human sperm after the swim-up preparation.

Authors:
Seul Ki Kim, M.D., Byung Chul Jee, M.D., Ph.D., Seok Hyun Kim, M.D., Ph.D.

Volume 103, Issue 6, Pages 1425-1431

Abstract:

Objective:
To assess global methylation and acetylation level before and after swim-up in ejaculated human sperm.

Design:
Prospective experimental study.

Setting:
University-based hospital.

Patient(s):
Semen samples were obtained from 50 healthy volunteers (single sample per person) between December 2012 and May 2014.

Intervention(s):
The semen samples were processed by the swim-up method.

Main Outcome Measure(s):
Sperm motility, strict morphology, DNA fragmentation index (DFI) by TUNEL, abnormal chromatin structure by toluidine blue staining, immunostaining of 8-hydroxy-2′-deoxyguanosine (8-OHdG) as an oxidative stress marker, immunostaining of 5-methyl-cytosine (5-mC) as a measurement of methylation level and immunostaining of six acetylation markers (H3K9ac, H3K14ac, H4K5ac, H4K8ac, H4K12ac, and H4K16ac) before and after swim-up.

Result(s):
After swim-up, motility and the percentage of normal form was significantly elevated. In the swim-up fraction, DFI and the percentage of abnormal chromatin structure were significantly lower and 8-OHdG levels were significantly higher. The 5-mC levels were significantly lower in the swim-up fraction, whereas no changes were observed in the positivity of six acetylation markers. Elevated percentage of normal form and decreased DFI and 5-mC levels were observed only in nonsmokers; 8-OHdG level was significantly higher in the swim-up fraction only from smokers. After swim-up, 5-mC levels were positively correlated with DFI.

Conclusion(s):
This is the first study demonstrating decreased methylation and unchanged acetylation patterns in human sperm after swim-up preparation.

  • ranjithrama

    This is an interesting study demonstrating association between methylation and patterns in sperm swim-up. It would be good to know whether these volunteers were fertile. Future studies need to focus on outcomes following sperm used from same semen sample comparing swim up vs. non swim up fraction. Increased methylation leading to decreased gene expression does not necessarily mean worse prognosis.

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