title: Evidence of gender-and tissue-specific promoter methylation and the potential for ethinylestradiol-induced changes in Japanese medaka (Oryzias latipes) estrogen receptor and aromatase genes.
abstract: In order to explore the potential of DNA methylation to serve as a biomarker of toxicity, thus establishing a link between exposure to environmental contaminants and physiologically significant changes in gene expression, tissue- and gender-specific methylation patterns in the promoter regions of estrogen receptor (ER) and aromatase genes of Japanese medaka (Oryzias latipes) were determined. Adult male and female medaka were exposed to either 0 or 500 ng/L 17 alpha-ethinylestradiol (EE) for 14d via a waterborne exposure. Livers, gonads, and brains were removed and genomic DNA was extracted. Samples of genomic DNA were then analyzed by bisulfite-mediated methylation-specific polymerase chain reaction (PCR) of an approximately 300-bp region containing suspected methylation sites from the two genes, amplified, cloned, and sequenced. ER protein content in exposed medaka was significantly induced in all male and female tissues compared to controls. Aromatase activity in exposed medaka was significantly increased in the male brain, testes, and female brain as compared to controls. The methylation changes described by these studies indicate the potential for anthropogenic alteration of the mechanisms controlling gene expression, as well as gender- and tissue-specific sensitivity. While methylation differences were not paralleled by changes in protein expression in this study, changes in methylation have the potential to impact the regulation of normal gene expression and these changes could be transmitted to offspring.
authors.affiliation: Department of Pharmacology and Environmental Toxicology Research Program, Research Institute of Pharmaceutical Sciences, University of Mississippi, University, MS 38677, USA.
authors.forename: Rooha G
authors.initials: RG
authors.lastname: Contractor
authors.forename: Christy M
authors.initials: CM
authors.lastname: Foran
authors.forename: Shuanfang
authors.initials: S
authors.lastname: Li
authors.forename: Kristine L
authors.initials: KL
authors.lastname: Willett
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001141:Aromatase / Q000032:analysis / Q000187:drug effects* / Q000235:genetics*; D015415:Biomarkers / Q000032:analysis; D015153:Blotting, Western; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D019175:DNA Methylation / Q000187:drug effects*; D004781:Environmental Exposure / Q000009:adverse effects / Q000032:analysis; D004784:Environmental Monitoring / Q000379:methods* / Q000592:standards; D044127:Epigenesis, Genetic / Q000187:drug effects / Q000235:genetics; D004997:Ethinyl Estradiol / Q000032:analysis / Q000633:toxicity*; D005260:Female; D015870:Gene Expression / Q000187:drug effects / Q000235:genetics; D006066:Gonads / Q000737:chemistry / Q000187:drug effects; D008099:Liver / Q000737:chemistry / Q000187:drug effects; D008297:Male; D008969:Molecular Sequence Data; D009990:Oryzias; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic / Q000187:drug effects* / Q000235:genetics*; D011960:Receptors, Estrogen / Q000032:analysis / Q000187:drug effects* / Q000235:genetics*; D012727:Sex Characteristics; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000633:toxicity
chemical_list: D015415:Biomarkers; D011960:Receptors, Estrogen; D014874:Water Pollutants, Chemical; D004997:Ethinyl Estradiol; D001141:Aromatase