Clin Exp Reprod Med.  2016 Jun;43(2):82-89. 10.5653/cerm.2016.43.2.82.

Epigenetic modification of long interspersed elements-1 in cumulus cells of mature and immature oocytes from patients with polycystic ovary syndrome

• Pruksananonda K
• Wasinarom
• Sereepapong W
• Sirayapiwat P
• Rattanatanyong P
• Mutirangura A

• KMID: 2308893
• DOI: http://doi.org/10.5653/cerm.2016.43.2.82

Abstract

OBJECTIVE
The long interspersed elements (LINE-1, L1s) are a group of genetic elements found in large numbers in the human genome that can translate into phenotype by controlling genes. Growing evidence supports the role of epigenetic in polycystic ovary syndrome (PCOS). The purpose of this study is to evaluate the DNA methylation levels in LINE-1 in a tissue-specific manner using cumulus cells from patients with PCOS compared with normal controls.
METHODS
The study included 19 patients with PCOS and 22 control patients who were undergoing controlled ovarian hyperstimulation. After oocyte retrieval, cumulus cells were extracted. LINE-1 DNA methylation levels were analysed by bisulfite treatment, polymerase chain reaction, and restriction enzyme digestion. The Connection Up- and Down-Regulation Expression Analysis of Microarrays software package was used to compare the gene regulatory functions of intragenic LINE-1.
RESULTS
The results showed higher LINE-1 DNA methylation levels in the cumulus cells of mature oocytes in PCOS patients, 79.14 (±2.66) vs. 75.40 (±4.92); p=0.004, but no difference in the methylation of cumulus cells in immature oocytes between PCOS and control patients, 70.33 (±4.79) vs. 67.79 (±5.17); p=0.155. However, LINE-1 DNA methylation levels were found to be higher in the cumulus cells of mature oocytes than in those of immature oocytes in both PCOS and control patients.
CONCLUSION
These findings suggest that the epigenetic modification of LINE-1 DNA may play a role in regulating multiple gene expression that affects the pathophysiology and development of mature oocytes in PCOS.

Keyword

Cumulus cell; DNA methylation; Epigenetic; Infertility; In vitro fertilization; Long interspersed nucleotide elements; Oocyte; Polycystic ovary syndrome

MeSH Terms

Cumulus Cells*
Digestion
DNA
DNA Methylation
Down-Regulation
Epigenomics*
Fertilization in Vitro
Gene Expression
Genome, Human
Humans
Infertility
Long Interspersed Nucleotide Elements
Methylation
Oocyte Retrieval
Oocytes*
Phenotype
Polycystic Ovary Syndrome*
Polymerase Chain Reaction
DNA