title: Cloning and characterization of estrogen receptor alpha in mummichog, Fundulus heteroclitus.
abstract: Developmental exposure to 17 beta-estradiol (E(2)) induced the death of embryos and fry, malformations, sex reversal, and incomplete ossification of vertebrae and cranial bones in the cyprinodont fish, the mummichog (Fundulus heteroclitus). To clarify the mechanism by which exogenous estrogens caused these developmental effects, we determined the sequence of an estrogen receptor (ER) coding region, encoded by 620 amino acid residues. This region shared 80% identity to that of ER alpha of medaka (Oryzias latipes). Northern blot analysis showed that two ER alpha mRNAs with 5.5 and 4 kb were expressed in the liver. These mRNAs were strongly induced by E(2) stimulation. The 4 kb mRNA was expressed 8 h after treatment, whereas the 5.5 kb mRNA was not induced until 12 h after E(2) stimulation. Vitellogenin (VTG) was expressed 8 h after E(2) stimulation in the male liver. Receptor binding assays using the protein of F. heteroclitus ER alpha (fh ER alpha) ligand binding domain showed that alkylphenols bind to fh ER alpha with a higher affinity (50 times or more) as compared with the human ER alpha. The present results demonstrate that the fh ER alpha has a sequence very similar to that of medaka, and the mRNA for this receptor was induced by E(2)-stimulation, followed subsequently by VTG expression. Furthermore, alkylphenols bind to fh ER alpha more efficiently than to human ER alpha.
authors.affiliation: Graduate School of Integrated Science, Yokohama City University, 22-2 Seto, Kanazawa-ku, Yokohama 236-0027, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Urushitani
authors.forename: Makoto
authors.initials: M
authors.lastname: Nakai
authors.forename: Hideko
authors.initials: H
authors.lastname: Inanaga
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Shimohigashi
authors.forename: Akio
authors.initials: A
authors.lastname: Shimizu
authors.forename: Yoshinao
authors.initials: Y
authors.lastname: Katsu
authors.forename: Taisen
authors.initials: T
authors.lastname: Iguchi
mesh_terms: D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004625:Embryo, Nonmammalian; D045166:Estradiol Congeners / Q000494:pharmacology*; D047628:Estrogen Receptor alpha; D005260:Female; D005399:Fishes; D023781:Fundulidae / Q000235:genetics*; D008099:Liver / Q000378:metabolism; D008297:Male; D008969:Molecular Sequence Data; D010802:Phylogeny; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000096:biosynthesis; D011960:Receptors, Estrogen / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D014819:Vitellogenins / Q000096:biosynthesis; D014874:Water Pollutants, Chemical / Q000494:pharmacology
chemical_list: D045166:Estradiol Congeners; D047628:Estrogen Receptor alpha; D012333:RNA, Messenger; D011960:Receptors, Estrogen; D014819:Vitellogenins; D014874:Water Pollutants, Chemical