title: Sharing the Roles: An Assessment of Japanese Medaka Estrogen Receptors in Vitellogenin Induction.
abstract: Teleost fish express at least three estrogen receptor (ER) subtypes. To date, however, the individual role of these ER subtypes in regulating expression of estrogen responsive genes remains ambiguous. Here, we investigate putative roles of three ER subtypes in Japanese medaka (Oryzias latipes), using vitellogenin (VTG) I and II as model genes. We identify specific ligand/receptor/promoter dynamics, using transient transactivation assays that incorporate luciferase reporters comprising 3kb promoter/enhancer regions of medaka VTGI and VTGII genes. Four steroidal estrogens (17β-estradiol, estrone, estriol, and 17α-estradiol) were tested in these assays. Results indicate that all three medaka ERs (mERs) are capable of initiating transactivation of both VTG I and II, with ERβ2 exhibiting greatest activity. Promoter deletion analysis suggests that ligand-specific receptor transactivation and utilization of regional-specific estrogen response elements may be associated with differential activities of each medaka ER. Further, cluster analysis of in vivo gene expression and in vitro transactivation suggests that all three ER subtypes putatively play a role in up-regulation of VTG. Results illustrate that preferential ligand/receptor/promoter interactions may have direct implications for VTG gene expression and other ER-mediated regulatory functions that are relevant to the risk assessment of estrogenic compounds.
authors.affiliation: Department of Biological Sciences, Environmental and Molecular Toxicology Program, North Carolina State University , 850 Main Campus Drive, Raleigh, North Carolina 27606, United States.
authors.forename: Crystal S D
authors.initials: CS
authors.lastname: Lee Pow
authors.affiliation: Department of Biological Sciences, Environmental and Molecular Toxicology Program, North Carolina State University , 850 Main Campus Drive, Raleigh, North Carolina 27606, United States.
authors.forename: Erin E
authors.initials: EE
authors.lastname: Yost
authors.affiliation: Department of Applied Ecology, North Carolina State University , 127 David Clark Laboratories, Raleigh, North Carolina 27695, United States.
authors.forename: D Derek
authors.initials: DD
authors.lastname: Aday
authors.affiliation: Department of Biological Sciences, Environmental and Molecular Toxicology Program, North Carolina State University , 850 Main Campus Drive, Raleigh, North Carolina 27606, United States.
authors.forename: Seth W
authors.initials: SW
authors.lastname: Kullman
mesh_terms: D000818:Animals; D001681:Biological Assay; D004958:Estradiol / Q000378:metabolism; D004967:Estrogens / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects; D009990:Oryzias / Q000378:metabolism*; D011960:Receptors, Estrogen / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects; D014819:Vitellogenins / Q000378:metabolism
chemical_list: D004967:Estrogens; D011960:Receptors, Estrogen; D014819:Vitellogenins; D004958:Estradiol