scholarly journals NRIF3 Is a Novel Coactivator Mediating Functional Specificity of Nuclear Hormone Receptors

1999 ◽  
Vol 19 (10) ◽  
pp. 7191-7202 ◽  
Author(s):  
Dangsheng Li ◽  
Vandana Desai-Yajnik ◽  
Eric Lo ◽  
Matthieu Schapira ◽  
Ruben Abagyan ◽  
...  
Keyword(s):  
Nuclear Receptors ◽  
Transcriptional Activation ◽  
Hormone Receptors ◽  
Target Genes ◽  
Thyroid Hormone Receptor ◽  
Specific Interaction ◽  
Minor Role ◽  
Receptor Specificity ◽  
Terminal Domain

ABSTRACT Many nuclear receptors are capable of recognizing similar DNA elements. The molecular event(s) underlying the functional specificities of these receptors (in regulating the expression of their native target genes) is a very important issue that remains poorly understood. Here we report the cloning and analysis of a novel nuclear receptor coactivator (designated NRIF3) that exhibits a distinct receptor specificity. Fluorescence microscopy shows that NRIF3 localizes to the cell nucleus. The yeast two-hybrid and/or in vitro binding assays indicated that NRIF3 specifically interacts with the thyroid hormone receptor (TR) and retinoid X receptor (RXR) in a ligand-dependent fashion but does not bind to the retinoic acid receptor, vitamin D receptor, progesterone receptor, glucocorticoid receptor, or estrogen receptor. Functional experiments showed that NRIF3 significantly potentiates TR- and RXR-mediated transactivation in vivo but has little effect on other examined nuclear receptors. Domain and mutagenesis analyses indicated that a novel C-terminal domain in NRIF3 plays an essential role in its specific interaction with liganded TR and RXR while the N-terminal LXXLL motif plays a minor role in allowing optimum interaction. Computer modeling and subsequent experimental analysis suggested that the C-terminal domain of NRIF3 directly mediates interaction with liganded receptors through an LXXIL (a variant of the canonical LXXLL) module while the other part of the NRIF3 protein may still play a role in conferring its receptor specificity. Identification of a coactivator with such a unique receptor specificity may provide new insight into the molecular mechanism(s) of receptor-mediated transcriptional activation as well as the functional specificities of nuclear receptors.

Nuclear Hormone Receptors and Gene Expression

2001 ◽  
Vol 81 (3) ◽  
pp. 1269-1304 ◽  
Author(s):  
Ana Aranda ◽  
Angel Pascual
Keyword(s):  
Gene Expression ◽  
Nuclear Receptors ◽  
Transcriptional Activation ◽  
Transcriptional Repression ◽  
Hormone Receptors ◽  
Target Genes ◽  
Specific Interaction ◽  
Nuclear Hormone Receptor ◽  
Transcriptional Responses ◽  
Orphan Receptors

The nuclear hormone receptor superfamily includes receptors for thyroid and steroid hormones, retinoids and vitamin D, as well as different “orphan” receptors of unknown ligand. Ligands for some of these receptors have been recently identified, showing that products of lipid metabolism such as fatty acids, prostaglandins, or cholesterol derivatives can regulate gene expression by binding to nuclear receptors. Nuclear receptors act as ligand-inducible transcription factors by directly interacting as monomers, homodimers, or heterodimers with the retinoid X receptor with DNA response elements of target genes, as well as by “cross-talking” to other signaling pathways. The effects of nuclear receptors on transcription are mediated through recruitment of coregulators. A subset of receptors binds corepressor factors and actively represses target gene expression in the absence of ligand. Corepressors are found within multicomponent complexes that contain histone deacetylase activity. Deacetylation leads to chromatin compactation and transcriptional repression. Upon ligand binding, the receptors undergo a conformational change that allows the recruitment of multiple coactivator complexes. Some of these proteins are chromatin remodeling factors or possess histone acetylase activity, whereas others may interact directly with the basic transcriptional machinery. Recruitment of coactivator complexes to the target promoter causes chromatin decompactation and transcriptional activation. The characterization of corepressor and coactivator complexes, in concert with the identification of the specific interaction motifs in the receptors, has demonstrated the existence of a general molecular mechanism by which different receptors elicit their transcriptional responses in target genes.

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.

Abstract P244: Transcriptional Regulation of Cardiac Gene Expression by Med13 Alters Global Energy Balance

2011 ◽  
Vol 109 (suppl_1) ◽  
Author(s):  
Chad E Grueter ◽  
Brett A Johnson ◽  
Xiaoxia Qi ◽  
John McAnally ◽  
Rhonda Bassel-Duby ◽  
...  
Keyword(s):  
Gene Expression ◽  
Energy Balance ◽  
Hormone Receptor ◽  
Hormone Receptors ◽  
Target Genes ◽  
Thyroid Hormone Receptor ◽  
Cardiac Contractility ◽  
Nuclear Hormone Receptor ◽  
Mediator Complex

Aberrant cardiac metabolism is associated with obesity, type 2 diabetes and heart failure. The heart requires highly efficient metabolism to maintain the levels of ATP needed for contractility and pump function, however little is known about the role of the heart as a metabolic organ. Nuclear hormone receptors, such as thyroid hormone receptor play an important role in cardiovascular disease by significantly altering expression of genes involved in maintaining metabolic activity. The Mediator, a large multiprotein complex functions as a hub to control gene expression through association with transcriptional activators and repressors. We tested the hypothesis that Med13, a component of the Mediator complex, regulates cardiac function in a gain-of-function mouse model. Trangsenic mice overexpressing Med13 in the heart are lean, have increased energy expenditure, are resistant to high fat diet-induced obesity and have enhanced cardiac contractility. Microarray analysis and biochemical assays show that in vivo and in vitro Med13 selectively inhibits nuclear hormone receptor target genes of energy metabolism. These results implicate the Mediator complex regulates energy balance and cardiac contractility and suggests that the heart may function as a key component of mammalian energy homeostasis.

Co-operation between protein-acetylating and protein-methylating co-activators in transcriptional activation

2000 ◽  
Vol 28 (4) ◽  
pp. 415-418 ◽  
Author(s):  
M. R. Stallcup ◽  
D. Chen ◽  
S. S. Koh ◽  
H. Ma ◽  
Y.-H. Lee ◽  
...  
Keyword(s):  
Transcriptional Activation ◽  
Transcription Initiation ◽  
Protein Modification ◽  
Hormone Receptors ◽  
Target Genes ◽  
Reporter Genes ◽  
Specific Protein ◽  
Synergistic Enhancement ◽  
Arginine Residues

Nuclear hormone receptors (NRs) activate transcription by binding to specific enhancer elements associated with target genes. Transcriptional activation is accomplished with the help of complexes of co-activator proteins that bind to NRs. p160 co-activators, a family of three related 160 kDa proteins, serve as primary co-activators by binding directly to NRs and recruiting additional secondary co-activators. Some of these (CBP/p300 and p/CAF) can acetylate histones and other proteins in the transcription complex, thus helping to modify chromatin structure and form an active transcription initiation complex. We recently discovered co-activator-associated arginine methyltransferase 1 (CARM1), which binds to p160 co-activators and thereby enhances transcriptional activation by NRs on transiently transfected reporter genes. CARM1 also methylates specific arginine residues in the N-terminal tail of histone H3 in vitro. A related arginine-specific protein methyltransferase, PRMT1, also binds p160 co-activators and enhances NR function. PRMT1 methylates histone H4 in vitro. The enhancement of NR function by CARM1, PRMT1 and p300 depends on their interactions with p160 co-activators. In the presence of p160 co-activators, some pairs of these three secondary co-activators provide a highly synergistic enhancement of NR function on transiently transfected reporter genes. We have also observed an enhancement of NR function on stably integrated reporter genes by these co-activators. We propose that the synergy of co-activator function between p300, CARM1 and PRMT1 is due to their different but complementary protein modification activities.

scholarly journals The DRIP Complex and SRC-1/p160 Coactivators Share Similar Nuclear Receptor Binding Determinants but Constitute Functionally Distinct Complexes

2000 ◽  
Vol 20 (8) ◽  
pp. 2718-2726 ◽  
Author(s):  
Christophe Rachez ◽  
Matthew Gamble ◽  
Chao-Pei Betty Chang ◽  
G. Brandon Atkins ◽  
Mitchell A. Lazar ◽  
...  
Keyword(s):  
Nuclear Receptors ◽  
Nuclear Receptor ◽  
Receptor Binding ◽  
Transcriptional Activation ◽  
Thyroid Hormone Receptor ◽  
Nuclear Receptor Coactivators ◽  
Nuclear Extracts ◽  
Sequence Requirements

ABSTRACT Transcriptional activation requires both access to DNA assembled as chromatin and functional contact with components of the basal transcription machinery. Using the hormone-bound vitamin D3receptor (VDR) ligand binding domain (LBD) as an affinity matrix, we previously identified a novel multisubunit coactivator complex, DRIP (VDR-interacting proteins), required for transcriptional activation by nuclear receptors and several other transcription factors. In this report, we characterize the nuclear receptor binding features of DRIP205, a key subunit of the DRIP complex, that interacts directly with VDR and thyroid hormone receptor in response to ligand and anchors the other DRIP subunits to the nuclear receptor LBD. In common with other nuclear receptor coactivators, DRIP205 interaction occurs through one of two LXXLL motifs and requires the receptor's AF-2 subdomain. Although the second motif of DRIP205 is required only for VDR binding in vitro, both motifs are used in the context of an retinoid X receptor-VDR heterodimer on DNA and in transactivation in vivo. We demonstrate that both endogenous p160 coactivators and DRIP complexes bind to the VDR LBD from nuclear extracts through similar sequence requirements, but they do so as distinct complexes. Moreover, in contrast to the p160 family of coactivators, the DRIP complex is devoid of any histone acetyltransferase activity. The results demonstrate that different coactivator complexes with distinct functions bind to the same transactivation region of nuclear receptors, suggesting that they are both required for transcription activation by nuclear receptors.

Activation Functions 1 and 2 of Nuclear Receptors: Molecular Strategies for Transcriptional Activation

2003 ◽  
Vol 17 (10) ◽  
pp. 1901-1909 ◽  
Author(s):  
Anette Wärnmark ◽  
Eckardt Treuter ◽  
Anthony P. H. Wright ◽  
Jan-Åke Gustafsson
Keyword(s):  
Transcription Factors ◽  
Rna Polymerase Ii ◽  
Nuclear Receptors ◽  
Transcriptional Activation ◽  
Molecular Mechanisms ◽  
Target Genes ◽  
Current Knowledge ◽  
Preinitiation Complex ◽  
Activation Domains ◽  
Terminal Domain

Abstract Nuclear receptors (NRs) comprise a family of ligand inducible transcription factors. To achieve transcriptional activation of target genes, DNA-bound NRs directly recruit general transcription factors (GTFs) to the preinitiation complex or bind intermediary factors, so-called coactivators. These coactivators often constitute subunits of larger multiprotein complexes that act at several functional levels, such as chromatin remodeling, enzymatic modification of histone tails, or modulation of the preinitiation complex via interactions with RNA polymerase II and GTFs. The binding of NR to coactivators is often mediated through one of its activation domains. Many NRs have at least two activation domains, the ligand-independent activation function (AF)-1, which resides in the N-terminal domain, and the ligand-dependent AF-2, which is localized in the C-terminal domain. In this review, we summarize and discuss current knowledge regarding the molecular mechanisms of AF-1- and AF-2-mediated gene activation, focusing on AF-1 and AF-2 conformation and coactivator binding.

scholarly journals A shift in the ligand responsiveness of thyroid hormone receptor alpha induced by heterodimerization with retinoid X receptor alpha.

1996 ◽  
Vol 16 (1) ◽  
pp. 219-227 ◽  
Author(s):  
F X Claret ◽  
T Antakly ◽  
M Karin ◽  
F Saatcioglu
Keyword(s):  
Thyroid Hormone ◽  
Dna Binding ◽  
Conformational Changes ◽  
Transcriptional Activation ◽  
Target Genes ◽  
Thyroid Hormone Receptor ◽  
Transcriptional Responses ◽  
Receptor Alpha

Thyroid hormone (T3) receptors (T3Rs) are ligand-modulated transcription factors that bind to thyroid hormone response elements (T3REs) and mediate either positive or negative transcriptional regulation of target genes. In addition, in response to ligand binding, T3Rs can interfere with AP-1 activity and thereby inhibit transcription of AP-1-responsive genes. T3Rs were recently shown to form heterodimers with retinoid X receptors (RXRs), leading to increased binding to T3REs in vitro and potentiation of transcriptional responses in vivo. Here we demonstrate that T3R alpha forms stable heterodimers with RXR alpha in living cells. Most important, we describe a new role for RXR alpha in modulating ligand-dependent T3R alpha activity: heterodimerization with RXR alpha greatly increases transcriptional interference with AP-1 activity, augments T3-dependent transcriptional activation, and potentiates the reversal of ligand-independent activation by T3R alpha. In all three cases, the responses occur at substantially lower T3 concentrations when elicited by T3R alpha plus RXR alpha than by T3R alpha alone. In vitro, the binding of T3 decreases the DNA-binding activity of T3R alpha homodimers but does not affect DNA binding by T3R alpha:RXR alpha heterodimers. We provide evidence that increased activities of T3R alpha at lower T3 concentrations are not due to changes in its T3 binding properties. Instead, the altered response could be mediated by either RXR alpha-induced conformational changes, increased stability of heterodimers over homodimers, especially following T3 binding, or both.

scholarly journals Methylcytosine dioxygenase TET3 interacts with thyroid hormone nuclear receptors and stabilizes their association to chromatin

2017 ◽  
Vol 114 (31) ◽  
pp. 8229-8234 ◽  
Author(s):  
Wenyue Guan ◽  
Romain Guyot ◽  
Jacques Samarut ◽  
Frédéric Flamant ◽  
Jiemin Wong ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Nuclear Receptors ◽  
Transcriptional Activation ◽  
Hormone Receptors ◽  
Target Genes ◽  
Nuclear Hormone Receptor ◽  
Regulatory Function ◽  
Interacting Protein ◽  
Differential Ability ◽  
Dominant Activity

Thyroid hormone receptors (TRs) are members of the nuclear hormone receptor superfamily that act as ligand-dependent transcription factors. Here we identified the ten-eleven translocation protein 3 (TET3) as a TR interacting protein increasing cell sensitivity to T3. The interaction between TET3 and TRs is independent of TET3 catalytic activity and specifically allows the stabilization of TRs on chromatin. We provide evidence that TET3 is required for TR stability, efficient binding of target genes, and transcriptional activation. Interestingly, the differential ability of different TRα1 mutants to interact with TET3 might explain their differential dominant activity in patients carrying TR germline mutations. So this study evidences a mode of action for TET3 as a nonclassical coregulator of TRs, modulating its stability and access to chromatin, rather than its intrinsic transcriptional activity. This regulatory function might be more general toward nuclear receptors. Indeed, TET3 interacts with different members of the superfamily and also enhances their association to chromatin.

scholarly journals Interaction between the trout mineralocorticoid and glucocorticoid receptors in vitro

2015 ◽  
Vol 55 (1) ◽  
pp. 55-68 ◽  
Author(s):  
Pia Kiilerich ◽  
Gérard Triqueneaux ◽  
Nynne Meyn Christensen ◽  
Vincent Trayer ◽  
Xavier Terrien ◽  
...  
Keyword(s):  
Dna Binding ◽  
Transcriptional Activation ◽  
Transcriptional Activity ◽  
Glucocorticoid Receptors ◽  
Hormone Receptors ◽  
Target Genes ◽  
Cell Types ◽  
Dominant Negative ◽  
Site Directed Mutagenesis

The salmonid corticosteroid receptors (CRs), glucocorticoid receptors 1 and 2 (GR1 and GR2) and the mineralocorticoid receptor (MR) share a high degree of homology with regard to structure, ligand- and DNA response element-binding, and cellular co-localization. Typically, these nuclear hormone receptors homodimerize to confer transcriptional activation of target genes, but a few studies using mammalian receptors suggest some degree of heterodimerization. We observed that the trout MR confers a several fold lower transcriptional activity compared to the trout GRs. This made us question the functional relevance of the MR when this receptor is located in the same cells as the GRs and activated by cortisol. A series of co-transfection experiments using different glucocorticoid response elements (GREs) containing promoter-reporter constructs were carried out to investigate any possible interaction between the piscine CRs. Co-transfection of the GRs with the MR significantly reduced the total transcriptional activity even at low MR levels, suggesting interaction between these receptors. Co-transfection of GR1 or GR2 with the MR did not affect the subcellular localization of the GRs, and the MR-mediated inhibition seemed to be independent of specific activation or inhibition of the MR. Site-directed mutagenesis of the DNA-binding domain and dimerization interface of the MR showed that the inhibition was dependent on DNA binding but not necessarily on dimerization ability. Thus, we suggest that the interaction between MR and the GRs may regulate the cortisol response in cell types where the receptors co-localize and propose a dominant-negative role for the MR in cortisol-mediated transcriptional activity.

scholarly journals Tri-iodothyronine-induced increase in rat liver nuclear thyroid-hormone receptors associated with increased mitochondrial α-glycerophosphate dehydrogenase activity

1979 ◽  
Vol 182 (2) ◽  
pp. 371-375 ◽  
Author(s):  
S Hamada ◽  
H Nakamura ◽  
M Nanno ◽  
H Imura
Keyword(s):  
Thyroid Hormone ◽  
Dehydrogenase Activity ◽  
Nuclear Receptors ◽  
Rat Liver ◽  
Hormone Receptors ◽  
Thyroid Hormone Receptor ◽  
Histone Protein ◽  
Glycerophosphate Dehydrogenase ◽  
Hormonal Modulation

The effect of tri-iodothyronine injection on the nuclear tri-iodothyronine receptor (putative thyroid-hormone receptor) was examined in rat liver. Nuclear receptors were extracted from isolated nuclei with 0.4 M-KCl, and their association constants (Ka) and maximal binding capacities (Cmax.) were determined by Scatchard analyses with and without correction for the endogenous hormone. The amount of endogenous tri-iodothyronine bound to non-histone protein was estimated on the basis of the specific radio-activity of [125I]tri-iodothyronine injected 2 h before the rats were killed. It was demonstrated that Cmax. of the nuclear receptors was 2.5-fold higher in severely hyperthyroid than in hypothyroid rats. However, irrespective of the thyroid status, the Ka of the receptors remained unchanged when corrected for endogenous tri-iodothyronine bound to non-histone protein. The validity of the correction was supported by experiments in vitro in which nuclear receptors were preincubated with unlabelled tri-iodothyronine. The increase in Cmax. of nuclear receptors was directly related to mitochondrial alpha-glycerophosphate dehydrogenase activity. These results suggest a hormonal modulation of the nuclear receptors which is associated with hormonal action.

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