Inhibition of GATA2-dependent transactivation of the TSHbeta gene by ligand-bound estrogen receptor alpha.
Transcriptional repression of the TSH-specific beta subunit (TSHbeta) gene has been regarded to be specific to thyroid hormone (tri-iodothyronine, T(3)) and its receptors (TRs) in physiological conditions. However, TSHbeta mRNA levels in the pituitary were reported to decrease in the administration of pharmacologic doses of estrogen (17-beta-estradiol, E(2)) and increase in E(2) receptor (ER)-alpha null mice. Here, we investigated the molecular mechanism of inhibition of the TSHbeta gene expression by E(2)-bound E(2)-estrogen receptor 1 (E(2)-ERalpha). In kidney-derived CV1 cells, transcriptional activity of the TSHbeta promoter was stimulated by GATA2 and suppressed by THRBs and ERalpha in a ligand-dependent fashion. Overexpression of PIT1 diminished the E(2)-ERalpha-induced inhibition, suggesting that PIT1 may protect GATA2 from E(2)-ERalpha targeting by forming a stable complex with GATA2. Interacting surfaces between ERalpha and GATA2 were mapped to the DNA-binding domain (DBD) of ERalpha and the Zn finger domain of GATA2. E(2)-dependent inhibition requires the ERalpha amino-terminal domain but not the tertiary structure of the second Zn finger motif in E(2)-ERalpha-DBD. In the thyrotroph cell line, TalphaT1, E(2) treatment reduced TSHbeta mRNA levels measured by the reverse transcription PCR. In the human study, despite similar free thyroxine levels, the serum TSH level was small but significantly higher in post- than premenopausal women who possessed no anti-thyroid antibodies (1.90 microU/ml+/-0.13 S.E.M. vs 1.47 microU/ml+/-0.12 S.E.M., P<0.05). Our findings indicate redundancy between T(3)-TR and E(2)-ERalpha signaling exists in negative regulation of the TSHbeta gene.
Nagayama
Koji
K
Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka 431-3192, Japan.
Sasaki
Shigekazu
S
Matsushita
Akio
A
Ohba
Kenji
K
Iwaki
Hiroyuki
H
Matsunaga
Hideyuki
H
Suzuki
Shingo
S
Misawa
Hiroko
H
Ishizuka
Keiko
K
Oki
Yutaka
Y
Noh
Jaeduk Yoshimura
JY
Nakamura
Hirotoshi
H
D000328:Adult; D000818:Animals; D002460:Cell Line; D002522:Chlorocebus aethiops; D024202:Electrophoretic Mobility Shift Assay; D004958:Estradiol / Q000097:blood / Q000378:metabolism / Q000494:pharmacology; D047628:Estrogen Receptor alpha / Q000737:chemistry / Q000378:metabolism*; D050989:GATA2 Transcription Factor / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology*; D006801:Humans; D017698:Postmenopause / Q000097:blood; D017697:Premenopause / Q000097:blood; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D020133:Reverse Transcriptase Polymerase Chain Reaction; D037322:Thyrotropin, beta Subunit / Q000235:genetics*; D013974:Thyroxine / Q000097:blood; D050817:Transcription Factor Pit-1 / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation / Q000187:drug effects*; D014284:Triiodothyronine / Q000097:blood; D016335:Zinc Fingers / Q000502:physiology
D047628:Estrogen Receptor alpha; D050989:GATA2 Transcription Factor; D037322:Thyrotropin, beta Subunit; D050817:Transcription Factor Pit-1; D014284:Triiodothyronine; D004958:Estradiol; D013974:Thyroxine