title: Cloning of circadian rhythmic pathway genes and perturbation of oscillation patterns in endocrine disrupting chemicals (EDCs)-exposed mangrove killifish Kryptolebias marmoratus.
abstract: To investigate the effect of endocrine disrupting chemicals (EDCs) on the circadian rhythm pathway, we cloned clock and circadian rhythmic pathway-associated genes (e.g. Per2, Cry1, Cry2, and BMAL1) in the self-fertilizing mangrove killifish Kryptolebias marmoratus. The promoter region of Km-clock had 1 aryl hydrocarbon receptor element (AhRE, GTGCGTGACA) and 8 estrogen receptor (ER) half-sites, indicating that the AhRE and ER half sites would likely be associated with regulation of clock protein activity during EDCs-induced cellular stress. The Km-clock protein domains (bHLH, PAS1, PAS2) were highly conserved in five additional fish species (zebrafish, Japanese medaka, Southern platyfish, Nile tilapia, and spotted green pufferfish), suggesting that the fish clock protein may play an important role in controlling endogenous circadian rhythms. The promoter regions of Km-BMAL1, -Cry1, -Cry2, and -Per2 were found to contain several xenobiotic response elements (XREs), indicating that EDCs may be able to alter the expression of these genes. To analyze the endogenous circadian rhythm in K. marmoratus, we measured expression of Km-clock and other circadian rhythmic genes (e.g. Per2, Cry1, Cry2, and BMAL1) in different tissues, and found ubiquitous expression, although there were different patterns of transcript amplification during different developmental stages. In an estrogen (E2)-exposed group, Km-clock expression was down-regulated, however, a hydroxytamoxifen (TMX, nonsteroid estrogen antagonist)-exposed group showed an upregulated pattern of Km-clock expression, suggesting that the expression of Km-clock is closely associated with exposure to EDCs. In response to the exposure of bisphenol A (BPA) and 4-tert-octyphenol (OP), Km-clock expression was down-regulated in the pituitary/brain, muscle, and skin in both gender types (hermaphrodite and secondary male). In juvenile K. marmoratus liver tissue, expression of Km-clock and other circadian rhythmic pathway-associated genes showed a regular oscillation pattern over a period of approximately 24h during a 12L:12D cycle. However, the circadian rhythm of BPA-exposed juvenile K. marmoratus liver tissue was perturbed over a 12L:12D period. This study will aid in our understanding of how EDCs perturb endogenous circadian rhythms, particularly in BPA-exposed fish liver tissue.
authors.affiliation: Department of Marine Science, College of Natural Sciences, Incheon National University, Incheon 406-772, South Korea.
authors.forename: Jae-Sung
authors.initials: JS
authors.lastname: Rhee
authors.affiliation: Department of Biological Sciences, College of Science, Sungkyunkwan University, Suwon 440-746, South Korea.
authors.forename: Bo-Mi
authors.initials: BM
authors.lastname: Kim
authors.affiliation: Department of Biological Sciences, College of Science, Sungkyunkwan University, Suwon 440-746, South Korea.
authors.forename: Bo-Young
authors.initials: BY
authors.lastname: Lee
authors.affiliation: Marine Ecological Risk Assessment Center, West Sea Fisheries Research Institute, National Fisheries Research & Development Institute, Incheon 400-420, South Korea.
authors.forename: Un-Ki
authors.initials: UK
authors.lastname: Hwang
authors.affiliation: Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul 133-791, South Korea.
authors.forename: Yong Sung
authors.initials: YS
authors.lastname: Lee
authors.affiliation: Department of Biological Sciences, College of Science, Sungkyunkwan University, Suwon 440-746, South Korea. Electronic address: jslee2@skku.edu.
authors.forename: Jae-Seong
authors.initials: JS
authors.lastname: Lee
mesh_terms: D000818:Animals; D001559:Benzhydryl Compounds / Q000633:toxicity; D002940:Circadian Rhythm / Q000187:drug effects* / Q000235:genetics; D003001:Cloning, Molecular; D012734:Disorders of Sex Development / Q000235:genetics; D052244:Endocrine Disruptors / Q000633:toxicity*; D005260:Female; D029941:Fish Proteins / Q000235:genetics; D005786:Gene Expression Regulation / Q000187:drug effects; D007695:Killifishes / Q000235:genetics / Q000502:physiology*; D008099:Liver / Q000187:drug effects / Q000502:physiology; D008297:Male; D008969:Molecular Sequence Data; D010636:Phenols / Q000633:toxicity; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D013629:Tamoxifen / Q000031:analogs & derivatives / Q000633:toxicity; D014874:Water Pollutants, Chemical / Q000633:toxicity; D000098826:Bisphenol A Compounds
chemical_list: D001559:Benzhydryl Compounds; D052244:Endocrine Disruptors; D029941:Fish Proteins; D010636:Phenols; D013629:Tamoxifen; D014874:Water Pollutants, Chemical; C016601:afimoxifene; C006780:bisphenol A; D000098826:Bisphenol A Compounds
keywords: Circadian rhythm; Clock; Endocrine disrupting chemicals; Fish; Kryptolebias marmoratus