title: Aberrant Epigenetic Alterations of Glutathione-S-Transferase P1 in Age-Related Nuclear Cataract.
abstract: Oxidative damage of lens tissue contributes to the formation of age-related cataract. Pi-class glutathione-S-transferase (GSTP1) plays a role in the removal of oxidative adducts by transferring them to glutathione. To assess epigenetic regulation of GSTP1 and its potential role in age-related nuclear cataract (ARNC) pathogenesis, we evaluated GSTP1 mRNA expression, methylation, and chromatin modifications in lenses from ARNC patients.
  
  
  
  The mRNA and protein of lens GSTP1 were assayed by relative quantitative real-time polymerase chain reaction (qRT-PCR) and Western blots. Methylation of the GSTP1 promoter was determined by bisulfite genomic sequencing. Chromatin modification was detected by chromatin immunoprecipitation. DNA methyltransferase (DNMT) and histone deacetylase (HDAC) activities were also assayed by enzyme-linked immunosorbent assay (ELISA)-like reaction. To assess the effect of DNA methylation on the mRNA expression of GSTP1, human lens epithelium HLE-B3 cells were treated with the demethylation compound 5-aza-dC, followed by qRT-PCR assay.
  
  
  
  GSTP1 mRNA and protein levels were significantly reduced in lens epithelium and cortex of ARNC cases versus age-matched controls. The changes corresponded to hypermethylation of the GSTP1 promoter CpG islands. The loss of GSTP1 mRNA and protein and the increased DNA promoter methylation might be correlated with the severity of the ARNC. ARNC lenses also had lower acetylation of histone proteins H3, H4, and lower methylation of H3K4, and higher methylation of H3K9. Histone modifications were not correlated with the severity of the ARNCs. DNMT and HDAC were elevated in lenses from ARNCs compared with controls. Demethylation treatment of HLE-B3 cells with 5-aza-dC enhanced the expression of GSTP1.
  
  
  
  Epigenetic alteration of GSTP1 regulates its expression in lens epithelial and cortical tissues. These changes likely contribute to the pathogenesis of ARNC.
authors.affiliation: a Eye Institute, Affiliated Hospital of Nantong University , Nantong , China.
authors.forename: Jia
authors.initials: J
authors.lastname: Chen
authors.affiliation: a Eye Institute, Affiliated Hospital of Nantong University , Nantong , China.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhou
authors.affiliation: a Eye Institute, Affiliated Hospital of Nantong University , Nantong , China.
authors.forename: Jian
authors.initials: J
authors.lastname: Wu
authors.affiliation: a Eye Institute, Affiliated Hospital of Nantong University , Nantong , China.
authors.forename: Guowei
authors.initials: G
authors.lastname: Zhang
authors.affiliation: a Eye Institute, Affiliated Hospital of Nantong University , Nantong , China.
authors.forename: Lihua
authors.initials: L
authors.lastname: Kang
authors.affiliation: a Eye Institute, Affiliated Hospital of Nantong University , Nantong , China.
authors.forename: Jindong
authors.initials: J
authors.lastname: Ben
authors.affiliation: a Eye Institute, Affiliated Hospital of Nantong University , Nantong , China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Wang
authors.affiliation: a Eye Institute, Affiliated Hospital of Nantong University , Nantong , China.
authors.forename: Bai
authors.initials: B
authors.lastname: Qin
authors.affiliation: a Eye Institute, Affiliated Hospital of Nantong University , Nantong , China.
authors.forename: Huaijin
authors.initials: H
authors.lastname: Guan
mesh_terms: D000368:Aged; D015153:Blotting, Western; D002386:Cataract / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D002478:Cells, Cultured; D044127:Epigenesis, Genetic; D004847:Epithelial Cells / Q000378:metabolism / Q000473:pathology; D005260:Female; D005786:Gene Expression Regulation; D051549:Glutathione S-Transferase pi / Q000096:biosynthesis / Q000235:genetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012333:RNA, Messenger / Q000235:genetics*; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D012333:RNA, Messenger; C496556:GSTP1 protein, human; D051549:Glutathione S-Transferase pi
keywords: Age-related cataract; DNA methylation; epigenetic; glutathione-S-transferase; histone modification