Altered DNA Methylation Patterns of the H19 Differentially Methylated Region and the DAZL Gene Promoter Are Associated with Defective Human Sperm

Abstract

DNA methylation disturbance is associated with defective human sperm. However, oligozoospermia (OZ) and asthenozoospermia (AZ) usually present together, and the relationship between the single-phenotype defects in human sperm and DNA methylation is poorly understood. In this study, 20 infertile OZ patients and 20 infertile AZ patients were compared with 20 fertile normozoospermic men. Bisulfate-specific PCR was used to analyze DNA methylation of the H19-DMR and the DAZL promoter in these subjects. A similar DNA methylation pattern of the H19-DMR was detected in AZ and NZ(control), with only complete methylation and mild hypomethylation(<50% unmethylated CpGs) identified, and there was no significant difference in the occurrence of these two methylation patterns between AZ and NZ (P>0.05). However, the methylation pattern of severe hypomethylation (>50% unmethylated CpGs ) and complete unmethylation was only detected in 5 OZ patients, and the occurrence of these two methylation patterns was 8.54±10.86% and 9±6.06%, respectively. Loss of DNA methylation of the H19-DMR in the OZ patients was found to mainly occur in CTCF-binding site 6, with occurrence of 18.15±14.71%, which was much higher than that in patients with NZ (0.84±2.05%) and AZ (0.58±1.77%) (P<0.001).Additional, our data indicated the occurrence of >20% methylated clones in the DAZL promoter only in infertile patients, there was no significant difference between the AZ and OZ patients in the proportion of moderately-to-severely hypermethylated clones (p>0.05). In all cases, global sperm genome methylation analyses, using LINE1 transposon as the indicator, showed that dysregulation of DNA methylation is specifically associated with the H19-DMR and DAZL promoter. Therefore, abnormal DNA methylation status of H19-DMR, especially at the CTCF-binding site 6, is closely associated with OZ. Abnormal DNA methylation of the DAZL promoter might represent an epigenetic marker of male infertility.

Effects on specific promoter DNA methylation in zebrafish embryos and larvae following benzo[a]pyrene exposure

“…dazl is an important gene for spermatogenesis (Rengaraj et al, 2010). In mammals, dazl deficiency leads to spermatogenic arrest and alterations in promoter DNA methylation of dazl have been found in poor quality sperm (Li et al, 2013; Krausz et al, 2012; Navarro-Costa et al, 2010). Therefore, aberrant methylation of dazl may contribute to impaired fertility in adulthood.…”

The role of epigenetics in idiopathic male infertility

“…Global/genome-wide and gene-specific DNA methylation Although most studies have focused on aberrant epigenetic marks of imprinted genes [47,58,[63][64][65][66][67], several studies have shown associations between aberrant DNA methylation of non-imprinted genes and oligozoospermia, abnormal sperm morphology, and motility. Recently, Urdinguio and colleagues showed alterations in methylation pattern of 2752 CGIs of genomic sperm DNA in idiopathic infertile males compared with fertile men.…”

“…DAZL promoter methylated only in infertile patents [47] Global Infertile males (38) • Hypermethylation in spermatogenesis-related genes • Loss of methylation in inflammation and immune response-related genes [18] Global NOA (65) and oligoastenozoospermic (29)…”

The Role of CCCTC-Binding Factor (CTCF) in Genomic Imprinting, Development, and Reproduction1

“…Furthermore, DNA methylation alterations are associated with subfertility and/or infertility in humans and animals, and abnormal DNA methylation at the CTCF-binding site 6 of the H19 DMR is closely associated with oligozoospermia [114,115], azoospermia [116], teratozoospermia, and oligo-astheno-teratozoospermia [117] in humans, and altered conception rates in cattle [118]. Interestingly, the same sixth CTCF-binding site was found to be hypomethylated in placentas of pregnancies conceived by IVEP/ICSI [119].…”