scholarly journals The erbA oncogene represses the actions of both retinoid X and retinoid A receptors but does so by distinct mechanisms.

1993 ◽  
Vol 13 (10) ◽  
pp. 5970-5980 ◽  
Author(s):  
H W Chen ◽  
M L Privalsky
Keyword(s):  
Thyroid Hormone ◽  
Hormone Receptors ◽  
Thyroid Hormone Receptor ◽  
Dominant Negative ◽  
Nuclear Hormone Receptors ◽  
Dominant Negative Inhibitor ◽  
Dominant Negative Mutations ◽  
Microbial Systems ◽  
Dna Binding Properties ◽  
Activate Gene

Genetic lesions that function as dominant negative mutations in microbial systems have long been recognized. It is only relatively recently, however, that similar dominant negative mutations have been implicated as a basis for genetic and neoplastic disorders in vertebrates. We describe here a dissection of the actions of the erbA oncogene protein, an aberrant form of thyroid hormone receptor that acts as a dominant negative inhibitor of other nuclear hormone receptors. We demonstrate that the ErbA oncoprotein interferes with thyroid hormone and trans-retinoic acid receptors by competing for binding to the corresponding response elements. Heterodimerization of the ErbA oncoprotein with these receptors does not play an observable role in repression. In contrast, however, the ErbA oncoprotein does efficiently form a heterodimer with the retinoid X receptor (RXR) class of nuclear hormone receptors; complex formation enhances the DNA-binding properties of the ErbA protein but dramatically interferes with the ability of the RXR component to activate gene expression. Our results indicate that the erbA oncogene may play a previously unanticipated role in neoplasia by interfering with RXR function.

The erbA oncogene represses the actions of both retinoid X and retinoid A receptors but does so by distinct mechanisms

1993 ◽  
Vol 13 (10) ◽  
pp. 5970-5980
Author(s):  
H W Chen ◽  
M L Privalsky
Keyword(s):  
Thyroid Hormone ◽  
Hormone Receptors ◽  
Thyroid Hormone Receptor ◽  
Dominant Negative ◽  
Nuclear Hormone Receptors ◽  
Dominant Negative Inhibitor ◽  
Dominant Negative Mutations ◽  
Microbial Systems ◽  
Dna Binding Properties ◽  
Activate Gene

Genetic lesions that function as dominant negative mutations in microbial systems have long been recognized. It is only relatively recently, however, that similar dominant negative mutations have been implicated as a basis for genetic and neoplastic disorders in vertebrates. We describe here a dissection of the actions of the erbA oncogene protein, an aberrant form of thyroid hormone receptor that acts as a dominant negative inhibitor of other nuclear hormone receptors. We demonstrate that the ErbA oncoprotein interferes with thyroid hormone and trans-retinoic acid receptors by competing for binding to the corresponding response elements. Heterodimerization of the ErbA oncoprotein with these receptors does not play an observable role in repression. In contrast, however, the ErbA oncoprotein does efficiently form a heterodimer with the retinoid X receptor (RXR) class of nuclear hormone receptors; complex formation enhances the DNA-binding properties of the ErbA protein but dramatically interferes with the ability of the RXR component to activate gene expression. Our results indicate that the erbA oncogene may play a previously unanticipated role in neoplasia by interfering with RXR function.

scholarly journals Thyroid-hormone-dependent negative regulation of thyrotropin beta gene by thyroid hormone receptors: study with a new experimental system using CV1 cells

2004 ◽  
Vol 378 (2) ◽  
pp. 549-557 ◽  
Author(s):  
Keiko NAKANO ◽  
Akio MATSUSHITA ◽  
Shigekazu SASAKI ◽  
Hiroko MISAWA ◽  
Kozo NISHIYAMA ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Hormone Receptor ◽  
Hormone Receptors ◽  
Thyroid Hormone Receptor ◽  
Experimental System ◽  
Thyroid Stimulating Hormone ◽  
Negative Regulation ◽  
Dominant Negative ◽  
Negative Effects ◽  
Receptor Isoforms

The molecular mechanism involved in the liganded thyroid hormone receptor suppression of the TSHβ (thyroid-stimulating hormone β, or thyrotropin β) gene transcription is undetermined. One of the main reasons is the limitation of useful cell lines for the experiments. We have developed an assay system using non-pituitary CV1 cells and studied the negative regulation of the TSHβ gene. In CV1 cells, the TSHβ–CAT (chloramphenicol acetyltransferase) reporter was stimulated by Pit1 and GATA2 and suppressed by T3 (3,3´,5-tri-iodothyronine)-bound thyroid hormone receptor. The suppression was dependent on the amounts of T3 and the receptor. Unliganded receptor did not stimulate TSHβ activity, suggesting that the receptor itself is not an activator. Analyses using various receptor mutants revealed that the intact DNA-binding domain is crucial to the TSHβ gene suppression. Co-activators and co-repressors are not necessarily essential, but are required for the full suppression of the TSHβ gene. Among the three receptor isoforms, β2 exhibited the strongest inhibition and its protein level was the most predominant in a thyrotroph cell line, TαT1, in Western blotting. The dominant-negative effects of various receptor mutants measured on the TSHβ–CAT reporter were not simple mirror images of those in the positive regulation under physiological T3 concentration.

scholarly journals Hematopoiesis in aged female mice devoid of thyroid hormone receptors

2020 ◽  
Vol 244 (1) ◽  
pp. 83-94 ◽  
Author(s):  
Ángela Sánchez ◽  
Constanza Contreras-Jurado ◽  
Diego Rodríguez ◽  
Javier Regadera ◽  
Susana Alemany ◽  
...  
Keyword(s):  
Gene Expression ◽  
Thyroid Hormone ◽  
Thyroid Hormones ◽  
B Cell ◽  
Knockout Mice ◽  
Hormone Receptors ◽  
Thyroid Hormone Receptor ◽  
Dominant Negative ◽  
Thyroid Hormone Receptors ◽  
Female Mice

Hypothyroidism is often associated with anemia and immunological disorders. Similar defects are found in patients and in mice with a mutated dominant-negative thyroid hormone receptor α (TRα) and in knockout mice devoid of this receptor, suggesting that this isoform is responsible for the effects of the thyroid hormones in hematopoiesis. However, the hematological phenotype of mice lacking also TRβ has not yet been examined. We show here that TRα1/TRβ-knockout female mice, lacking all known thyroid hormone receptors with capacity to bind thyroid hormones, do not have overt anemia and in contrast with hypothyroid mice do not present reduced Gata1 or Hif1 gene expression. Similar to that found in hypothyroidism or TRα deficiency during the juvenile period, the B-cell population is reduced in the spleen and bone marrow of ageing TRα1/TRβ-knockout mice, suggesting that TRβ does not play a major role in B-cell development. However, splenic hypotrophy is more marked in hypothyroid mice than in TRα1/TRβ-knockout mice and the splenic population of T-lymphocytes is not significantly impaired in these mice in contrast with the reduction found in hypothyroidism. Our results show that the overall hematopoietic phenotype of the TRα1/TRβ-knockout mice is milder than that found in the absence of hormone. Although other mechanism/s cannot be ruled out, our results suggest that the unoccupied TRs could have a negative effect on hematopoiesis, likely secondary to repression of hematopoietic gene expression.

scholarly journals Alien, a Highly Conserved Protein with Characteristics of a Corepressor for Members of the Nuclear Hormone Receptor Superfamily

1999 ◽  
Vol 19 (5) ◽  
pp. 3383-3394 ◽  
Author(s):  
Uwe Dressel ◽  
Dorit Thormeyer ◽  
Boran Altincicek ◽  
Achim Paululat ◽  
Martin Eggert ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Hormone Receptor ◽  
Hormone Receptors ◽  
Thyroid Hormone Receptor ◽  
Retinoic Acid Receptor ◽  
Specific Interaction ◽  
Gene Activation ◽  
Nuclear Hormone Receptor ◽  
Nuclear Hormone Receptors ◽  
Reporter Assays

ABSTRACT Some members of nuclear hormone receptors, such as the thyroid hormone receptor (TR), silence gene expression in the absence of the hormone. Corepressors, which bind to the receptor’s silencing domain, are involved in this repression. Hormone binding leads to dissociation of corepressors and binding of coactivators, which in turn mediate gene activation. Here, we describe the characteristics of Alien, a novel corepressor. Alien interacts with TR only in the absence of hormone. Addition of thyroid hormone leads to dissociation of Alien from the receptor, as shown by the yeast two-hybrid system, glutathioneS-transferase pull-down, and coimmunoprecipitation experiments. Reporter assays indicate that Alien increases receptor-mediated silencing and that it harbors an autonomous silencing function. Immune staining shows that Alien is localized in the cell nucleus. Alien is a highly conserved protein showing 90% identity between human and Drosophila. Drosophila Alien shows similar activities in that it interacts in a hormone-sensitive manner with TR and harbors an autonomous silencing function. Specific interaction of Alien is seen with Drosophila nuclear hormone receptors, such as the ecdysone receptor and Seven-up, the Drosophila homologue of COUP-TF1, but not with retinoic acid receptor, RXR/USP, DHR 3, DHR 38, DHR 78, or DHR 96. These properties, taken together, show that Alien has the characteristics of a corepressor. Thus, Alien represents a member of a novel class of corepressors specific for selected members of the nuclear hormone receptor superfamily.

scholarly journals Dominant Inhibition of Thyroid Hormone Action Selectively in the Pituitary of Thyroid Hormone Receptor-β Null Mice Abolishes the Regulation of Thyrotropin by Thyroid Hormone

2003 ◽  
Vol 17 (9) ◽  
pp. 1767-1776 ◽  
Author(s):  
E. Dale Abel ◽  
Egberto G. Moura ◽  
Rexford S. Ahima ◽  
Angel Campos-Barros ◽  
Carmen C. Pazos-Moura ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Hormone Receptors ◽  
Thyroid Hormone Receptor ◽  
Feedback Inhibition ◽  
Fold Increase ◽  
Dominant Negative ◽  
Hypothalamic Nucleus ◽  
Relative Contribution ◽  
Pituitary Thyroid Axis ◽  
Thyroid Hormone Receptor Β

Abstract Thyroid hormones, T4 and T3, regulate their own production by feedback inhibition of TSH and TRH synthesis in the pituitary and hypothalamus when T3 binds to thyroid hormone receptors (TRs) that interact with the promoters of the genes for the TSH subunit and TRH. All TR isoforms are believed to be involved in the regulation of this endocrine axis, as evidenced by the massive dysregulation of TSH production in mice lacking all TR isoforms. However, the relative contributions of TR isoforms in the pituitary vs. the hypothalamus remain to be completely elucidated. Thus, to determine the relative contribution of pituitary expression of TR-α in the regulation of the hypothalamic-pituitary-thyroid axis, we selectively impaired TR-α function in TR-β null mice (TR-β−/−) by pituitary restricted expression of a dominant negative TR-β transgene harboring a Δ337T mutation. These animals exhibited 10-fold and 32-fold increase in T4 and TSH concentrations, respectively. Moreover, the negative regulation of TSH by exogenous T3 was completely absent and a paradoxical increase in TSH concentrations and TSH-β mRNA was observed. In contrast, prepro-TRH expression levels in T3-treated TR-β−/− were similar to levels observed in the Δ337/TR-β−/− mice, and ligand-independent activation of TSH in hypothyroid mice was equivalently impaired. Thus, isolated TR-β deficiency in TRH paraventricular hypothalamic nucleus neurons and impaired function of all TRs in the pituitary recapitulate the baseline hormonal disturbances that characterize mice with complete absence of all TRs.

scholarly journals Involvement of Histone Methylation and Phosphorylation in Regulation of Transcription by Thyroid Hormone Receptor

2002 ◽  
Vol 22 (16) ◽  
pp. 5688-5697 ◽  
Author(s):  
Jiwen Li ◽  
Qiushi Lin ◽  
Ho-Geun Yoon ◽  
Zhi-Qing Huang ◽  
Brian D. Strahl ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Histone Acetylation ◽  
Histone Methylation ◽  
Hormone Receptor ◽  
Transcriptional Control ◽  
Hormone Receptors ◽  
Thyroid Hormone Receptor ◽  
Nuclear Hormone Receptors ◽  
Regulation Of Transcription

ABSTRACT Previous studies have established an important role of histone acetylation in transcriptional control by nuclear hormone receptors. With chromatin immunoprecipitation assays, we have now investigated whether histone methylation and phosphorylation are also involved in transcriptional regulation by thyroid hormone receptor (TR). We found that repression by unliganded TR is associated with a substantial increase in methylation of H3 lysine 9 (H3-K9) and a decrease in methylation of H3 lysine 4 (H3-K4), methylation of H3 arginine 17 (H3-R17), and a dual modification of phosphorylation of H3 serine 10 and acetylation of lysine 14 (pS10/acK14). On the other hand, transcriptional activation by liganded TR is coupled with a substantial decrease in both H3-K4 and H3-K9 methylation and a robust increase in H3-R17 methylation and the dual modification of pS10/acK14. Trichostatin A treatment results in not only histone hyperacetylation but also an increase in methylation of H3-K4, increase in dual modification of pS10/acK14, and reduction in methylation of H3-K9, revealing an extensive interplay between histone acetylation, methylation, and phosphorylation. In an effort to understand the underlying mechanism for an increase in H3-K9 methylation during repression by unliganded TR, we demonstrated that TR interacts in vitro with an H3-K9-specific histone methyltransferase (HMT), SUV39H1. Functional analysis indicates that SUV39H1 can facilitate repression by unliganded TR and in so doing requires its HMT activity. Together, our data uncover a novel role of H3-K9 methylation in repression by unliganded TR and provide strong evidence for the involvement of multiple distinct histone covalent modifications (acetylation, methylation, and phosphorylation) in transcriptional control by nuclear hormone receptors.

scholarly journals Adipogenesis is differentially impaired by thyroid hormone receptor mutant isoforms

2010 ◽  
Vol 44 (4) ◽  
pp. 247-255 ◽  
Author(s):  
Alok Mishra ◽  
Xu-guang Zhu ◽  
Kai Ge ◽  
Sheue-Yann Cheng
Keyword(s):  
Thyroid Hormone ◽  
Hormone Receptors ◽  
Target Genes ◽  
Thyroid Hormone Receptor ◽  
Fold Increase ◽  
Dominant Negative ◽  
Peroxisome Proliferator ◽  
Loss Of Function ◽  
Peroxisome Proliferator Activated Receptor ◽  
Protein Levels

To understand the roles of thyroid hormone receptors (TRs) in adipogenesis, we adopted a loss-of-function approach. We generated 3T3-L1 cells stably expressing either TRα1 mutant (TRα1PV) or TRβ1 mutant (TRβ1PV). TRα1PV and TRβ1PV are dominant negative mutations with a frameshift in the C-terminal amino acids. In control cells, the thyroid hormone, tri-iodothyronine (T3), induced a 2.5-fold increase in adipogenesis in 3T3-L1 cells, as demonstrated by increased lipid droplets. This increase was mediated by T3-induced expression of the peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT/enhancer-binding protein α (C/EBPα), which are master regulators of adipogenesis at both the mRNA and protein levels. In 3T3-L1 cells stably expressing TRα1PV (L1-α1PV cells) or TRβ1PV (L1-β1PV cells), adipogenesis was reduced 94 or 54% respectively, indicative of differential inhibitory activity of mutant TR isoforms. Concordantly, the expression of PPARγ and C/EBPα at the mRNA and protein levels was more repressed in L1-α1PV cells than in L1-β1PV cells. In addition, the expression of PPARγ downstream target genes involved in fatty acid synthesis – the lipoprotein lipase (Lpl) and aP2 involved in adipogenesis – was more inhibited by TRα1PV than by TRβ1PV. Chromatin immunoprecipitation assays showed that TRα1PV was more avidly recruited than TRβ1PV to the promoter to preferentially block the expression of the C/ebpα gene. Taken together, these data indicate that impaired adipogenesis by mutant TR is isoform dependent. The finding that induction of adipogenesis is differentially regulated by TR isoforms suggests that TR isoform-specific ligands could be designed for therapeutic intervention for lipid abnormalities.

scholarly journals Residues K128, 132, and 134 in the Thyroid Hormone Receptor-α Are Essential for Receptor Acetylation and Activity

Endocrinology ◽  
2009 ◽  
Vol 150 (11) ◽  
pp. 5143-5152 ◽  
Author(s):  
Aurora Sánchez-Pacheco ◽  
Olaia Martínez-Iglesias ◽  
Marinela Méndez-Pertuz ◽  
Ana Aranda
Keyword(s):  
Thyroid Hormone ◽  
Hormone Receptor ◽  
Thyroid Hormone Receptor ◽  
Camp Response Element Binding ◽  
Dominant Negative ◽  
Independent Manner ◽  
Lysine Residues ◽  
Element Binding Protein ◽  
Dominant Negative Inhibitor ◽  
Fibroblast Transformation

The thyroid hormone receptor (TR)-α is a nuclear receptor that mediates both transrepression and ligand-dependent transactivation. Here we show that TRα is posttranslationally modified by acetylation in response to its own ligand (T3). Acetylation increases binding to DNA. Using mutagenesis, we identified three conserved lysine residues in the carboxi-terminal extension (CTE) of the DNA binding domain that are targets of the cAMP-response element-binding protein acetyltransferase. Substitution of these lysines by arginines in TRα decreased ligand binding affinity and precluded ligand-dependent release of corepressors and recruitment of coactivators. The acetylation TRα mutant lost the ability to transactivate even at high T3 concentrations and acts as a dominant-negative inhibitor of wild-type TR activity. In addition, whereas native TRα interferes with AP-1 function, the mutant is unable to mediate transrepression. Finally, TRα suppresses NIH-3T3 fibroblast transformation by the Ras oncogene both in a ligand-dependent and -independent manner, but the CTE mutant is unable to mediate ligand-dependent repression of transformation. These results reveal a key role for the CTE region on acetylation, ligand affinity, transactivation, transrepression, and antitransforming properties of TRα.

scholarly journals RORα Augments Thyroid Hormone Receptor-Mediated Transcriptional Activation*

Endocrinology ◽  
1999 ◽  
Vol 140 (3) ◽  
pp. 1356-1364 ◽  
Author(s):  
Noriyuki Koibuchi ◽  
Ying Liu ◽  
Harumi Fukuda ◽  
Akira Takeshita ◽  
Paul M. Yen ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Transcriptional Activation ◽  
Hormone Receptor ◽  
Hormone Receptors ◽  
Thyroid Hormone Receptor ◽  
Critical Role ◽  
Nuclear Hormone Receptor ◽  
Dominant Negative ◽  
Mobility Shift ◽  
Response Element

Abstract This study is designed to clarify the role of an orphan nuclear hormone receptor, RORα, on thyroid hormone (TH) receptor (TR)-mediated transcription on a TH-response element (TRE). A transient transfection study using various TREs [i.e., F2 (chick lysozyme TRE), DR4 (direct repeat), and palindrome TRE] and TR and RORα1 was performed. When RORα1 and TR were cotransfected into CV1 cells, RORα1 enhanced the transactivation by liganded-TR on all TREs tested without an effect on basal repression by unliganded TR. By electrophoretic mobility shift assay, on the other hand, although RORα bound to all TREs tested as a monomer, no (or weak) TR and RORα1 heterodimer formation was observed on various TREs except when a putative ROR-response element was present. The transactivation by RORα1 on a ROR-response element, which does not contain a TRE, was not enhanced by TR. The effect of RORα1 on the TREs is unique, because, whereas other nuclear hormone receptors (such as vitamin D receptor) may competitively bind to TRE to exert dominant negative function, RORα1 augmented TR action. These results indicate that RORα1 may modify the effect of liganded TR on TH-responsive genes. Because TR and RORα are coexpressed in cerebellar Purkinje cells, and perinatal hypothyroid animals and RORα-disrupted animals show similar abnormalities of this cell type, cross-talk between these two receptors may play a critical role in Purkinje cell differentiation.

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