Molecular characterization of three estrogen receptor forms in zebrafish: binding characteristics, transactivation properties, and tissue distributions.
There are two estrogen receptor (ER) subtypes in fish, ERalpha and ERbeta, and increasing evidence that the ERbeta subtype has more than one form. However, there is little information on the characteristics and functional significance of these ERs in adults and during development. Here, we report the cloning and characterization of three functional ER forms, zfERalpha, zfERbeta1, and zfERbeta2, in the zebrafish. The percentages of identity between these receptors suggest the existence of three distinct genes. Each cDNA encoded a protein that specifically bound estradiol with a dissociation constant ranging from 0.4 nM (zfERbeta2) to 0.75 nM (zfERalpha and zfERbeta1). In transiently transfected cells, all three forms were able to induce, in a dose-dependent manner, the expression of a reporter gene driven by a consensus estrogen responsive element; zfERbeta2 was slightly more sensitive than zfERalpha and zfERbeta1. Tissue distribution pattern, analyzed by reverse transcription polymerase chain reaction, showed that the three zfER mRNAs largely overlap and are predominantly expressed in brain, pituitary, liver, and gonads. In situ hybridization was performed to study in more detail the distribution of the three zfER mRNAs in the brain of adult females. The zfER mRNAs exhibit distinct but partially overlapping patterns of expression in two neuroendocrine regions, the preoptic area and the mediobasal hypothalamus. The characterization of these zfERs provides a new perspective for understanding the mechanisms underlying estradiol actions in a vertebrate species commonly used for developmental studies.
Menuet
Arnaud
A
Endocrinologie Moléculaire de la Reproduction, UMR CNRS 6026, Campus de Beaulieu, 35042 Rennes cedex, France.
Pellegrini
Elisabeth
E
Anglade
Isabelle
I
Blaise
Odile
O
Laudet
Vincent
V
Kah
Olivier
O
Pakdel
Farzad
F
D000595:Amino Acid Sequence; D000818:Animals; D001923:Brain Chemistry; D003001:Cloning, Molecular; D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D006801:Humans; D007033:Hypothalamus, Middle / Q000737:chemistry; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D010802:Phylogeny; D011301:Preoptic Area / Q000737:chemistry; D012333:RNA, Messenger / Q000032:analysis; D011960:Receptors, Estrogen / Q000032:analysis / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D017421:Sequence Analysis; D014018:Tissue Distribution; D015533:Transcriptional Activation; D014162:Transfection; D015027:Zebrafish / Q000378:metabolism*
D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D012333:RNA, Messenger; D011960:Receptors, Estrogen