title: Epigenetic modification of long interspersed elements-1 in cumulus cells of mature and immature oocytes from patients with polycystic ovary syndrome.
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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Reproductive Medicine Division, Department of Obstetrics and Gynecology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
authors.forename: Kamthorn
authors.initials: K
authors.lastname: Pruksananonda
authors.affiliation: Reproductive Medicine Division, Department of Obstetrics and Gynecology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
authors.forename: Artisa
authors.initials: A
authors.lastname: Wasinarom
authors.affiliation: Reproductive Medicine Division, Department of Obstetrics and Gynecology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
authors.forename: Wisan
authors.initials: W
authors.lastname: Sereepapong
authors.affiliation: Reproductive Medicine Division, Department of Obstetrics and Gynecology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
authors.forename: Porntip
authors.initials: P
authors.lastname: Sirayapiwat
authors.affiliation: Center of Excellence in Molecular Genetics of Cancer and Human Disease, Department of Anatomy, King Chulalongkorn Memorial Hospital, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
authors.forename: Prakasit
authors.initials: P
authors.lastname: Rattanatanyong
authors.affiliation: Center of Excellence in Molecular Genetics of Cancer and Human Disease, Department of Anatomy, King Chulalongkorn Memorial Hospital, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
authors.forename: Apiwat
authors.initials: A
authors.lastname: Mutirangura
keywords: Cumulus cell; DNA methylation; Epigenetic; In vitro fertilization; Infertility; Long interspersed nucleotide elements; Oocyte; Polycystic ovary syndrome