scholarly journals Activation of estrogen response element dependent transcription by thyroid hormone with increase in estrogen receptor levels in a rat pituitary cell line, GH3

2004 ◽  
Vol 181 (1) ◽  
pp. 77-83 ◽  
Author(s):  
N Fujimoto ◽  
N Jinno ◽  
S Kitamura
Keyword(s):  
Estrogen Receptor ◽  
Thyroid Hormone ◽  
Cell Line ◽  
Estrogen Receptor Alpha ◽  
Hormone Receptors ◽  
Target Genes ◽  
Progesterone Receptors ◽  
Pituitary Cell ◽  
Gh3 Cells

Interrelationships between thyroid hormone and estrogen actions have been documented with regard to a variety of physiological functions. Both hormones stimulate transcription of target genes by binding to their nuclear receptors that interact with specific responsive elements (estrogen and thyroid hormone response elements, i.e ERE and TRE, respectively) in the regulatory regions of the gene. In vitro studies have suggested that interplay between the two hormones might be due to cross-talk at hormone responsive elements, with the respective hormone receptors and ligands able to interact, although physiological relevance has yet to be proved. We have proposed a simpler mechanism for thyroid hormone effects on estrogen responses via increase in estrogen receptor alpha (ERalpha) with resultant increase in progesterone receptors, prolactin production and tumor growth. A pituitary cell line, GH3, has been widely used to investigate the function of mammo-somatotropic cells, especially regarding regulation of GH and prolactin production. In the present study, an ERE-luc reporter was transfected into GH3 cells and the responses to endogenous ERalpha were examined. We demonstrated that: (1)l -3,5,3'-triiodothyronine (T3) induces mRNA expression of ERalpha; (2) T3 alone is able to induce ERE-luc activity and this is inhibited by OH-tamoxifen; (3) T3 synergistically acts on estradiol (E2)-induced ERE responses; and (4) ERE-luc activity is enchanted by co-transfection of an ERalpha expression vector. These results support the hypothesis that estrogen responses are potentiated by T3 through up-regulation of ERalpha levels.

scholarly journals Do unliganded thyroid hormone receptors have physiological functions?

2003 ◽  
Vol 31 (1) ◽  
pp. 9-20 ◽  
Author(s):  
O Chassande
Keyword(s):  
Thyroid Hormone ◽  
Hormone Receptors ◽  
Target Genes ◽  
Thyroid Hormone Receptors ◽  
Intrinsic Activity ◽  
Vertebrate Development ◽  
Transcriptional Responses ◽  
Embryonic And Fetal Development

Thyroid hormone (TH) is required for the development of vertebrates and exerts numerous homeostatic functions in adults. TH acts through nuclear receptors which control the transcription of target genes. Unliganded and liganded thyroid hormone receptors (TRs) have been shown to exert opposite effects on the transcription of target genes in vitro. However, the occurance of an aporeceptor activity in vivo and its potential physiological significance has not been clearly addressed. Several data generated using experimental hypothyroidism and thyrotoxicosis in wild type and TR knockout mice support the notion that apoTRs have an intrinsic activity in several tIssues. ApoTRs, and in particular TRalpha1, are predominant during the early stages of vertebrate development and must be turned into holoTRs for post-natal development to proceed normally. However, the absence of striking alterations of embryonic and fetal development in mice devoid of TRs indicates that apoTRs do not play a fundamental role. During development, as well as in adults, apoTRs rather appears as a system which increases the range of transcriptional responses to moderate variations of T3.

scholarly journals The Role of Estriol and Estrone in Keratoconic Stromal Sex Hormone Receptors

2022 ◽  
Vol 23 (2) ◽  
pp. 916
Author(s):  
Paulina Escandon ◽  
Sarah E. Nicholas ◽  
Rebecca L. Cunningham ◽  
David A. Murphy ◽  
Kamran M. Riaz ◽  
...  
Keyword(s):  
Estrogen Receptor ◽  
Stromal Cells ◽  
Estrogen Receptor Alpha ◽  
Hormone Receptors ◽  
Estrogen Receptor Beta ◽  
Corneal Stroma ◽  
Sex Hormone ◽  
Human Cornea

Keratoconus (KC) is a progressive corneal thinning disease that manifests in puberty and worsens during pregnancy. KC onset and progression are attributed to diverse factors that include: environmental, genetics, and hormonal imbalances; however, the pathobiology remains elusive. This study aims to determine the role of corneal stroma sex hormone receptors in KC and their interplay with estrone (E1) and estriol (E3) using our established 3D in vitro model. Healthy cornea stromal cells (HCFs) and KC cornea stromal cells (HKCs), both male and female, were stimulated with various concentrations of E1 and E3. Significant changes were observed between cell types, as well as between males and females in the sex hormone receptors tested; androgen receptor (AR), progesterone receptor (PR), estrogen receptor alpha (ERα), and estrogen receptor beta (ERβ) using Western blot analysis. E1 and E3 stimulations in HCF females showed AR, PR, and ERβ were significantly upregulated compared to HCF males. In contrast, ERα and ERβ had significantly higher expression in HKC’s females than HKC’s males. Our data suggest that the human cornea is a sex-dependent, hormone-responsive tissue that is significantly influenced by E1 and E3. Therefore, it is plausible that E1, E3, and sex hormone receptors are involved in the KC pathobiology, warranting further investigation.

scholarly journals Coactivator Recruitment Is Essential for Liganded Thyroid Hormone Receptor To Initiate Amphibian Metamorphosis

2005 ◽  
Vol 25 (13) ◽  
pp. 5712-5724 ◽  
Author(s):  
Bindu Diana Paul ◽  
Liezhen Fu ◽  
Daniel R. Buchholz ◽  
Yun-Bo Shi
Keyword(s):  
Gene Regulation ◽  
Thyroid Hormone ◽  
Transcriptional Activation ◽  
Hormone Receptors ◽  
Target Genes ◽  
Thyroid Hormone Receptor ◽  
Dominant Negative ◽  
Amphibian Metamorphosis

ABSTRACT Thyroid hormone receptors (TRs) can repress or activate target genes depending on the absence or presence of thyroid hormone (T3), respectively. This hormone-dependent gene regulation is mediated by recruitment of corepressors in the absence of T3 and coactivators in its presence. Many TR-interacting coactivators have been characterized in vitro. In comparison, few studies have addressed the developmental roles of these cofactors in vivo. We have investigated the role of coactivators in transcriptional activation by TR during postembryonic tissue remodeling by using amphibian metamorphosis as a model system. We have previously shown that steroid receptor coactivator 3 (SRC3) is expressed and upregulated during metamorphosis, suggesting a role in gene regulation by liganded TR. Here, we have generated transgenic tadpoles expressing a dominant negative form of SRC3 (F-dnSRC3). The transgenic tadpoles exhibited normal growth and development throughout embryogenesis and premetamorphic stages. However, transgenic expression of F-dnSRC3 inhibits essentially all aspects of T3-induced metamorphosis, as well as natural metamorphosis, leading to delayed or arrested metamorphosis or the formation of tailed frogs. Molecular analysis revealed that F-dnSRC3 functioned by blocking the recruitment of endogenous coactivators to T3 target genes without affecting corepressor release, thereby preventing the T3-dependent gene regulation program responsible for tissue transformations during metamorphosis. Our studies thus demonstrate that coactivator recruitment, aside from corepressor release, is required for T3 function in development and further provide the first example where a specific coactivator-dependent gene regulation pathway by a nuclear receptor has been shown to underlie specific developmental events.

The functional relationship between co-repressor N-CoR and SMRT in mediating transcriptional repression by thyroid hormone receptor α

2008 ◽  
Vol 411 (1) ◽  
pp. 19-26 ◽  
Author(s):  
Kyung-Chul Choi ◽  
So-Young Oh ◽  
Hee-Bum Kang ◽  
Yoo-Hyun Lee ◽  
Seungjoo Haam ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Hormone Receptor ◽  
Transcriptional Repression ◽  
Fatty Acid Synthase ◽  
Hormone Receptors ◽  
Target Genes ◽  
Functional Relationship ◽  
Thyroid Hormone Receptor ◽  
B Cell Lymphoma ◽  
Hormone Response Elements

A central issue in mediating repression by nuclear hormone receptors is the distinct or redundant function between co-repressors N-CoR (nuclear receptor co-repressor) and SMRT (silencing mediator of retinoid and thyroid hormone receptor). To address the functional relationship between SMRT and N-CoR in TR (thyroid hormone receptor)-mediated repression, we have identified multiple TR target genes, including BCL3 (B-cell lymphoma 3-encoded protein), Spot14 (thyroid hormone-inducible hepatic protein), FAS (fatty acid synthase), and ADRB2 (β-adrenergic receptor 2). We demonstrated that siRNA (small interfering RNA) treatment against either N-CoR or SMRT is sufficient for the de-repression of multiple TR target genes. By the combination of sequence mining and physical association as determined by ChIP (chromatin immunoprecipitation) assays, we mapped the putative TREs (thyroid hormone response elements) in BCL3, Spot14, FAS and ADRB2 genes. Our data clearly show that SMRT and N-CoR are independently recruited to various TR target genes. We also present evidence that overexpression of N-CoR can restore repression of endogenous genes after knocking down SMRT. Finally, unliganded, co-repressor-free TR is defective in repression and interacts with a co-activator, p300. Collectively, these results suggest that both SMRT and N-CoR are limited in cells and that knocking down either of them results in co-repressor-free TR and consequently de-repression of TR target genes.

Characterization of a newly established uterine carcinosarcoma cell line featuring the sarcomatous phenotype of the tumor in vitro

2008 ◽  
Vol 18 (2) ◽  
pp. 339-344 ◽  
Author(s):  
H.-J. Schulten ◽  
J. Wolf-Salgó ◽  
C. Gründker ◽  
B. Gunawan ◽  
L. FÜZESI
Keyword(s):  
Cell Line ◽  
Hormone Receptors ◽  
Tumor Biology ◽  
Growth Factor Receptor ◽  
Population Doubling ◽  
Established Cell Line ◽  
Population Doubling Time ◽  
Uterine Carcinosarcoma ◽  
Specific Staining

We describe the newly established cell line CS-99 derived from a uterine carcinosarcoma retaining features of the sarcomatous phenotype in vitro. CS-99 cells exhibit a mesenchymal morphology with predominantly spindle-shaped cells at nonconfluence turning to pleomorphic appearance at confluence. The mesenchymal phenotype was evidenced immunohistochemically by strong vimentin and moderate SM-actin, which was similar to the sarcomatous component of the primary tumor. P53 was overexpressed in a subset of CS-99 cells. Epithelial membrane antigen was moderately expressed whereas other markers including pan CK, CK 5/6, CK 34, epidermal growth factor receptor, desmin, carcinoembryonic antigen, S100, KIT, ERBB2, and the hormone receptors, estrogen receptor and progesterone receptor revealed either weak or no specific staining in CS-99 cells. High self-renewal capacity corresponded to the population doubling time of 23 h in high passage. CS-99 cells were able to develop three-dimensional tumor spheroids in vitro. Cytogenetic analysis and multicolor fluorescence in situ hybridization of CS-99 demonstrated an almost stable karyotype including numerical changes +8, +18, and +20 and translocations, amongst others der(1)t(1;2), der(1)t(1;7), der(2)t(2;19), der(5)t(5;8), and der(5)t(5;14). Taken together, the cell line CS-99 exhibits strong growths dynamics and a complex but stable karyotype in higher passages, and can be further a useful in vitro model system for studying tumor biology of carcinosarcomas.

Ligand-dependent, Pit-1/growth hormone factor-1 (GHF-1)-independent transcriptional stimulation of rat growth hormone gene expression by thyroid hormone receptors in vitro

1993 ◽  
Vol 13 (3) ◽  
pp. 1719-1727
Author(s):  
C S Suen ◽  
W W Chin
Keyword(s):  
Gene Expression ◽  
Growth Hormone ◽  
Thyroid Hormone ◽  
Promoter Activity ◽  
Hormone Receptors ◽  
Nuclear Extract ◽  
In Vitro Transcription ◽  
Stimulation Of ◽  
Transcriptional Stimulation

The expression of the rat growth hormone (rGH) gene in the anterior pituitary gland is modulated by Pit-1/GHF-1, a pituitary-specific transcription factor, and by other more widely distributed factors, such as the thyroid hormone receptors (TRs), Sp1, and the glucocorticoid receptor. Thyroid hormone (T3)-mediated transcriptional stimulation of rGH gene expression has been extensively studied in vivo and in vitro including the measurements of (i) rGH mRNA by blot hybridization, (ii) transcriptional rate of rGH gene by nuclear run-on, and (iii) reporter gene expression in which a chimeric plasmid containing 5'-flanking sequences of the rGH gene linked to a reporter gene has been transfected either stably or transiently into pituitary and/or nonpituitary cells. From these studies, it has been suggested that the Pit-1/GHF-1 binding site is necessary for full T3 action. We developed a cell-free in vitro transcription system to examine further the roles of the TRs and Pit-1/GHF-1 in rGH gene activation. Using GH3 nuclear extract as a source of TRs and Pit-1/GHF-1, this in vitro transcription assay showed that T3 stimulation of rGH promoter activity is dependent on the addition of T3 to the GH3 nuclear extract. This transcriptional stimulation was augmented with increasing concentrations of ligand and was T3, but not T4 or reverse T3, specific. T3-mediated stimulation of rGH promoter activity was completely abolished by preincubation of the nuclear extract with rGH-thyroid hormone response element (-200 to -160) but not with Pit-1/GHF-1 (-137 to -65) oligonucleotides. Further, neither deletion of both Pit-1/GHF-1 binding sites nor mutation of the proximal Pit-1/GHF-1 binding site from the rGH promoter abrogated the T3 effect. These results provide evidence that T3-stimulated rGH promoter activity is independent of Pit-1/GHF-1 and raise the possibility that the stimulation of rGH gene expression by T3 might involve direct interaction of TRs with the general transcriptional apparatus.

A background sodium conductance is necessary for spontaneous depolarizations in rat pituitary cell line GH3

1994 ◽  
Vol 266 (3) ◽  
pp. C709-C719 ◽  
Author(s):  
S. M. Simasko
Keyword(s):  
Cell Line ◽  
Calcium Current ◽  
Membrane Conductance ◽  
Potassium Currents ◽  
Pituitary Cell ◽  
Calcium Currents ◽  
Gh3 Cells ◽  
Sodium Conductance ◽  
Rat Pituitary ◽  
Voltage Dependent

The role of Na+ in the expression of membrane potential activity in the clonal rat pituitary cell line GH3 was investigated using the perforated patch variation of patch-clamp electrophysiological techniques. It was found that replacing bath Na+ with choline, tris(hydroxymethyl)aminomethane (Tris), or N-methyl-D-glucamine (NMG) caused the cells to hyperpolarize 20-30 mV. Tetrodotoxin had no effect. The effects of the Na+ substitutes could not be explained by effects on potassium or calcium currents. Although all three Na+ substitutes suppressed voltage-dependent calcium current by 10-20%, block of voltage-dependent calcium current by nifedipine or Co2+ did not result in hyperpolarization of the cells. There was no effect of the Na+ substitutes on voltage-dependent potassium currents. In contrast, all three Na+ substitutes influenced calcium-activated potassium currents [IK(Ca)], but only at depolarized potentials. Choline consistently suppressed IK(Ca), whereas Tris and NMG either had no effect or slightly increased IK(Ca). These effects on IK(Ca) also cannot explain the hyperpolarization induced by removing bath Na+. Choline always hyperpolarized cells yet suppressed IK(Ca). Furthermore, removing bath Na+ caused an increase in cell input resistance, an observation consistent with the loss of a membrane conductance as the basis of the hyperpolarization. Direct measurement of background currents revealed a 12-pA inward current at -84 mV that was lost upon removing bath Na+. These results suggest that this background sodium conductance provides the depolarizing drive for GH3 cells to reach the threshold for firing calcium-dependent action potentials.

scholarly journals Regulation of functional steroid receptors and ligand-induced responses in telomerase-immortalized human endometrial epithelial cells

2005 ◽  
Vol 34 (2) ◽  
pp. 517-534 ◽  
Author(s):  
S Hombach-Klonisch ◽  
A Kehlen ◽  
P A Fowler ◽  
B Huppertz ◽  
J F Jugert ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Estrogen Receptor Alpha ◽  
Hormone Receptors ◽  
Steroid Receptors ◽  
Steroid Hormone ◽  
Three Dimensional ◽  
Steroid Hormone Receptors ◽  
Endogenous Estrogen ◽  
Endometrial Epithelial Cells

Information on the regulation of steroid hormone receptors and their distinct functions within the human endometrial epithelium is largely unavailable. We have immortalized human primary endometrial epithelial cells (EECs) isolated from a normal proliferative phase endometrium by stably transfecting the catalytic subunit (hTERT) of the human telomerase complex and cultured these hTERT-EECs now for over 350 population doublings. Active hTERT was detected in hTERT-EECs employing the telomerase repeat amplification assay protocol. hTERT-EECs revealed a polarized, non-invasive epithelial phenotype with apical microvilli and production of a basal lamina when grown on a three-dimensional collagen–fibroblast lattice. Employing atomic force microscopy, living hTERT-EECs were shown to produce extracellular matrix (ECM) components and ECM secretion was modified by estrogen and progesterone (P4). hTERT-EECs expressed inducible and functional endogenous estrogen receptor-alpha (ER-alpha) as demonstrated by estrogen response element reporter assays and induction of P4 receptor (PR). P4 treatment down-regulated PR expression, induced MUC-1 gene activity and resulted in increased ER-beta transcriptional activity. Gene activities of cytokines and their receptors interleukin (IL)-6, leukemia inhibitory factor (LIF), IL-11 and IL-6 receptor (IL6-R), LIF receptor and gp130 relevant to implantation revealed a 17 beta-estradiol (E2)-mediated up-regulation of IL-6 and an E2- and P4-mediated up-regulation of IL6-R in hTERT-EECs. Thus, hTERT-EECs may be regarded as a novel in vitro model to investigate the role of human EECs in steroid hormone-dependent normal physiology and pathologies, including implantation failure, endometriosis and endometrial cancer.

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