Molecular cloning and characterization of hagfish estrogen receptors.
One or more distinct forms of the nuclear estrogen receptor (ER) have been isolated from many vertebrates to date. To better understand the molecular evolution of ERs, we cloned and characterized er cDNAs from the inshore hagfish, Eptatretus burgeri, a modern representative of the most primitive vertebrates, the agnathans. Two er cDNAs, er1 and er2, were isolated from the liver of a reproductive female hagfish. A phylogenetic analysis placed hagfish ER1 into a position prior to the divergence of vertebrate ERs. Conversely, hagfish ER2 was placed at the base of the vertebrate ERβ clade. The tissue distribution patterns of both ER subtype mRNAs appeared to be different, suggesting that each subtype has different physiological roles associated with estrogen actions. An estrogen responsive-luciferase reporter assay using mammalian HEK293 cells was used to functionally characterize these hagfish ERs. Both ER proteins displayed estrogen-dependent activation of transcription. These results clearly demonstrate that the hagfish has two functional ER subtypes.
Laboratory of Fish Reproductive Physiology and Biochemistry, Division of Marine Life Sciences, Faculty of Fisheries Sciences, Hokkaido University, Hakodate, Hokkaido, 041-8611, Japan.
Osamu
O
Nishimiya
Laboratory of Reproductive and Developmental Biology, Department of Biological Sciences, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan.
Yoshinao
Y
Katsu
Department of Applied Aquabiology, National Fisheries University, Shimonoseki, Yamaguchi 759-6595, Japan.
Hiroyuki
H
Inagawa
Laboratory of Fish Reproductive Physiology and Biochemistry, Division of Marine Life Sciences, Faculty of Fisheries Sciences, Hokkaido University, Hakodate, Hokkaido, 041-8611, Japan.
Naoshi
N
Hiramatsu
Laboratory of Fish Reproductive Physiology and Biochemistry, Division of Marine Life Sciences, Faculty of Fisheries Sciences, Hokkaido University, Hakodate, Hokkaido, 041-8611, Japan. Electronic address: todo@fish.hokudai.ac.jp.
Takashi
T
Todo
Laboratory of Fish Reproductive Physiology and Biochemistry, Division of Marine Life Sciences, Faculty of Fisheries Sciences, Hokkaido University, Hakodate, Hokkaido, 041-8611, Japan.
Akihiko
A
Hara
D000818:Animals; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D047628:Estrogen Receptor alpha / Q000235:genetics; D047629:Estrogen Receptor beta / Q000235:genetics; D004967:Estrogens / Q000378:metabolism*; D019143:Evolution, Molecular; D005260:Female; D029941:Fish Proteins / Q000235:genetics / Q000378:metabolism*; D057809:HEK293 Cells; D006196:Hagfishes / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D008024:Ligands; D008297:Male; D010802:Phylogeny; D011960:Receptors, Estrogen / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D013045:Species Specificity; D014018:Tissue Distribution; D015533:Transcriptional Activation
D018076:DNA, Complementary; C506487:ESR1 protein, human; C000600034:ESR2 protein, human; D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D004967:Estrogens; D029941:Fish Proteins; D008024:Ligands; D011960:Receptors, Estrogen
Agnathan; Eptatretus burgeri; Estrogen receptor; Molecular cloning; Transactivation