Molecular cloning and characterization of ligand- and species-specificity of amphibian estrogen receptors.
Estrogens are essential for normal reproductive activity in both males and females as well as for ovarian differentiation during a critical developmental stage in most vertebrates. To understand the molecular mechanisms of estrogen action and to evaluate estrogen receptor ligand interactions in amphibians, we isolated cDNAs encoding the estrogen receptors (ERalpha and ERbeta) from the Japanese firebelly newt (Cynops pyrrhogaster), Tokyo salamander (Hynobius tokyoensis), axolotl (Ambystoma mexicanum), and Raucous toad (Bufo rangeri). Full-length amphibian ER cDNAs were obtained using 5' and 3' rapid amplification of cDNA ends. The predicted amino acid sequences of these amphibian ERs showed a high degree of amino acid sequence identity (over 70%) to each other. We analyzed the relationships of these amphibian ER sequences to other vertebrate ER sequences by constructing a phylogenetic tree. We verified that these were bona fide estrogen receptors using receptor dependent reporter gene assays. We analyzed the effects of natural estrogens, ethinylestradiol, and DDT and its metabolites on the transactivation of the four amphibian species listed above, and Xenopus tropicalis ERs and found that there were species-specific differences in the sensitivity of these ERs to hormones and environmental chemicals. These findings will expand our knowledge of endocrine-disrupting events in amphibians.
Katsu
Yoshinao
Y
Okazaki Institute for Integrative Bioscience, National Institute for Basic Biology, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki 444-8787, Japan.
Taniguchi
Ena
E
Urushitani
Hiroshi
H
Miyagawa
Shinichi
S
Takase
Minoru
M
Kubokawa
Kaoru
K
Tooi
Osamu
O
Oka
Tomohiro
T
Santo
Noriaki
N
Myburgh
Jan
J
Matsuno
Akira
A
Iguchi
Taisen
T
D000558:Ambystoma mexicanum / Q000235:genetics / Q000378:metabolism; D029845:Amphibian Proteins / Q000145:classification* / Q000235:genetics / Q000378:metabolism*; D000663:Amphibians / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001001:Anura / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D047628:Estrogen Receptor alpha / Q000145:classification / Q000235:genetics / Q000378:metabolism; D047629:Estrogen Receptor beta / Q000145:classification / Q000235:genetics / Q000378:metabolism; D005260:Female; D008297:Male; D011960:Receptors, Estrogen / Q000145:classification* / Q000235:genetics / Q000378:metabolism*; D012455:Salamandridae / Q000235:genetics / Q000378:metabolism; D014562:Caudata / Q000235:genetics / Q000378:metabolism
D029845:Amphibian Proteins; D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D011960:Receptors, Estrogen