Dominant-negative mutant thyroid hormone receptors prevent transcription from Xenopus thyroid hormone receptor beta gene promoter in response to thyroid hormone in Xenopus tadpoles in vivo.

Abstract Studies using mice deficient in thyroid hormone receptors (TR) indicate that the two TR isoforms, TRα1 and TRβ1, in addition to mediating overlapping biological activities of the thyroid hormone, T3, also mediate distinct functions. Mice harboring an identical dominant negative mutation (denoted PV) at the C terminus of TRα1 (Thra1PV mice) or β1 (ThrbPV mice) also exhibit distinct phenotypes. These knockin mutant mice provide an opportunity to understand the molecular basis of isoform-dependent functions in vivo. Here we tested the hypothesis that the distinct functions of TR mutant isoforms are directed by a subset of nuclear regulatory proteins. Tandem-affinity chromatography of HeLa nuclear extracts showed that distinct 33 nuclear proteins including nuclear receptor corepressor (NCoR1) and six other proteins preferentially associated with TRα1PV or TRβ1PV, respectively. These results indicate that recruitment of nuclear regulatory proteins by TR mutants is subtype dependent. The involvement of NCoR1 in mediating the distinct liver phenotype of Thra1PV and ThrbPV mice was further explored. NCoR1 preferentially interacted with TRα1PV rather than with TRβ1PV. NCoR1 was recruited more avidly to the thyroid hormone response element-bound TRα1PV than to TRβ1PV in the promoter of the CCAAT/enhancer-binding protein α gene to repress its expression in the liver of Thra1PV mice, but not in ThrbPV mice. This preferential recruitment of NCoR1 by mutant isoforms could contribute, at least in part, to the distinct liver lipid phenotype of these mutant mice. The present study highlights a novel mechanism by which TR isoforms direct their selective functions via preferential recruitment of a subset of nuclear coregulatory proteins.

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Hematopoiesis in aged female mice devoid of thyroid hormone receptors

Journal of Endocrinology ◽

10.1530/joe-19-0339 ◽

2020 ◽

Vol 244 (1) ◽

pp. 83-94 ◽

Cited By ~ 1

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.

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Jab1 is a T2-dependent coactivator or a T3-dependent corepressor of TRB1-mediated gene regulation

Journal of Endocrinology ◽

10.1530/joe-16-0485 ◽

2017 ◽

Vol 232 (3) ◽

pp. 451-459 ◽

Cited By ~ 6

Author(s):

Gabriela Hernández-Puga ◽

Arturo Mendoza ◽

Alfonso León-del-Río ◽

Aurea Orozco

Keyword(s):

Thyroid Hormone ◽

Hormone Receptors ◽

Thyroid Hormone Receptor ◽

Thyroid Hormone Receptors ◽

Biological Processes ◽

Yeast Two Hybrid ◽

Activation Domain ◽

Pleiotropic Actions ◽

Two Hybrid ◽

Receptor Beta

Thyroid hormones (THs) induce pleiotropic effects in vertebrates, mainly through the activation or repression of gene expression. These mechanisms involve thyroid hormone binding to thyroid hormone receptors, an event that is followed by the sequential recruitment of coactivator or corepressor proteins, which in turn modify the rate of transcription. In the present study, we looked for specific coregulators recruited by the long isoform of the teleostean thyroid hormone receptor beta 1 (L-Trb1) when bound to the bioactive TH, 3,5-T2 (T2). We found that jun activation domain-binding protein1 (Jab1) interacts with L-Trb1 + T2 complex. Using both the teleostean and human TRB1 isoforms, we characterized the Jab1–TRB1 by yeast two-hybrid, pull-down and transactivation assays. Our results showed that the TRB1–Jab1 interaction was ligand dependent and involved the single Jab1 nuclear receptor box, as well as the ligand-binding and N-terminal domains of TRB1. We also provide evidence of ligand-dependent, dual coregulatory properties of Jab1. Indeed, when T2 is bound to L-Trb1 or hTRB1, Jab1 acts as a coactivator of transcription, whereas it has corepressor activity when interacting with the T3-bound S-Trb1 or hTRB1. These mechanisms could explain some of the pleiotropic actions exerted by THs to regulate diverse biological processes.

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Nontranscriptional modulation of intracellular Ca2+ signaling by ligand stimulated thyroid hormone receptor

The Journal of Cell Biology ◽

10.1083/jcb.200409011 ◽

2004 ◽

Vol 167 (5) ◽

pp. 915-924 ◽

Cited By ~ 28

Author(s):

Nuttawut Saelim ◽

Linu M. John ◽

Jun Wu ◽

Jeong Soon Park ◽

Yidong Bai ◽

...

Keyword(s):

Thyroid Hormone ◽

Hormone Receptor ◽

Transcriptional Activity ◽

Hormone Receptors ◽

Thyroid Hormone Receptor ◽

Wave Activity ◽

Ruthenium Red ◽

Thyroid Hormone Receptors ◽

Localization Signal ◽

Receptor Beta

Thyroid hormone 3,5,3′-tri-iodothyronine (T3) binds and activates thyroid hormone receptors (TRs). Here, we present evidence for a nontranscriptional regulation of Ca2+ signaling by T3-bound TRs. Treatment of Xenopus thyroid hormone receptor beta subtype A1 (xTRβA1) expressing oocytes with T3 for 10 min increased inositol 1,4,5-trisphosphate (IP3)-mediated Ca2+ wave periodicity. Coexpression of TRβA1 with retinoid X receptor did not enhance regulation. Deletion of the DNA binding domain and the nuclear localization signal of the TRβA1 eliminated transcriptional activity but did not affect the ability to regulate Ca2+ signaling. T3-bound TRβA1 regulation of Ca2+ signaling could be inhibited by ruthenium red treatment, suggesting that mitochondrial Ca2+ uptake was required for the mechanism of action. Both xTRβA1 and the homologous shortened form of rat TRα1 (rTRαΔF1) localized to the mitochondria and increased O2 consumption, whereas the full-length rat TRα1 did neither. Furthermore, only T3-bound xTRβA1 and rTRαΔF1 affected Ca2+ wave activity. We conclude that T3-bound mitochondrial targeted TRs acutely modulate IP3-mediated Ca2+ signaling by increasing mitochondrial metabolism independently of transcriptional activity.

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Impaired Adipogenesis Caused by a Mutated Thyroid Hormone α1 Receptor

Molecular and Cellular Biology ◽

10.1128/mcb.02189-06 ◽

2007 ◽

Vol 27 (6) ◽

pp. 2359-2371 ◽

Cited By ~ 53

Author(s):

Hao Ying ◽

Osamu Araki ◽

Fumihiko Furuya ◽

Yasuhito Kato ◽

Sheue-Yann Cheng

Keyword(s):

Thyroid Hormone ◽

Thyroid Hormone Receptor ◽

Dominant Negative ◽

Dominant Negative Mutant ◽

Peroxisome Proliferator ◽

Peroxisome Proliferator Activated Receptor ◽

Protein Levels ◽

Reduced Body ◽

X Receptors

ABSTRACT Thyroid hormone (T3) is critical for growth, differentiation, and maintenance of metabolic homeostasis. Mice with a knock-in mutation in the thyroid hormone receptor α gene (TRα1PV) were created previously to explore the roles of mutated TRα1 in vivo. TRα1PV is a dominant negative mutant with a frameshift mutation in the carboxyl-terminal 14 amino acids that results in the loss of T3 binding and transcription capacity. Homozygous knock-in TRα1PV/PV mice are embryonic lethal, and heterozygous TRα1PV/+ mice display the striking phenotype of dwarfism. These mutant mice provide a valuable tool for identifying the defects that contribute to dwarfism. Here we show that white adipose tissue (WAT) mass was markedly reduced in TRα1PV/+ mice. The expression of peroxisome proliferator-activated receptor γ (PPARγ), the key regulator of adipogenesis, was repressed at both mRNA and protein levels in WAT of TRα1PV/+ mice. Moreover, TRα1PV acted to inhibit the transcription activity of PPARγ by competition with PPARγ for binding to PPARγ response elements and for heterodimerization with the retinoid X receptors. The expression of TRα1PV blocked the T3-dependent adipogenesis of 3T3-L1 cells and repressed the expression of PPARγ. Thus, mutations of TRα1 severely affect adipogenesis via cross talk with PPARγ signaling. The present study suggests that defects in adipogenesis could contribute to the phenotypic manifestation of reduced body weight in TRα1PV/+ mice.

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

Molecular and Cellular Biology ◽

10.1128/mcb.25.13.5712-5724.2005 ◽

2005 ◽

Vol 25 (13) ◽

pp. 5712-5724 ◽

Cited By ~ 51

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.

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The thyroid hormone receptor gene (c-erbA alpha) is expressed in advance of thyroid gland maturation during the early embryonic development of Xenopus laevis.

Molecular and Cellular Biology ◽

10.1128/mcb.11.10.5079 ◽

1991 ◽

Vol 11 (10) ◽

pp. 5079-5089 ◽

Cited By ~ 35

Author(s):

D E Banker ◽

J Bigler ◽

R N Eisenman

Keyword(s):

Gene Expression ◽

Thyroid Hormone ◽

Thyroid Gland ◽

Xenopus Laevis ◽

Hormone Receptor ◽

Hormone Receptors ◽

Thyroid Hormone Receptor ◽

Thyroid Hormone Receptors ◽

Stages Of Development ◽

Xenopus Development

The c-erbA proto-oncogene encodes the thyroid hormone receptor, a ligand-dependent transcription factor which plays an important role in vertebrate growth and development. To define the role of the thyroid hormone receptor in developmental processes, we have begun studying c-erbA gene expression during the ontogeny of Xenopus laevis, an organism in which thyroid hormone has well-documented effects on morphogenesis. Using polymerase chain reactions (PCR) as a sensitive assay of specific gene expression, we found that polyadenylated erbA alpha RNA is present in Xenopus cells at early developmental stages, including the fertilized egg, blastula, gastrula, and neurula. By performing erbA alpha-specific PCR on reverse-transcribed RNAs from high-density sucrose gradient fractions prepared from early-stage embryos, we have demonstrated that these erbA transcripts are recruited to polysomes. Therefore, erbA is expressed in Xenopus development prior to the appearance of the thyroid gland anlage in tailbud-stage embryos. This implies that erbA alpha/thyroid hormone receptors may play ligand-independent roles during the early development of X. laevis. Quantitative PCR revealed a greater than 25-fold range in the steady-state levels of polyadenylated erbA alpha RNA across early stages of development, as expressed relative to equimolar amounts of total embryonic RNA. Substantial increases in the levels of erbA alpha RNA were noted at stages well after the onset of zygotic transcription at the mid-blastula transition, with accumulation of erbA alpha transcripts reaching a relative maximum in advance of metamorphosis. We also show that erbA alpha RNAs are expressed unequally across Xenopus neural tube embryos. This differential expression continues through later stages of development, including metamorphosis. This finding suggests that erbA alpha/thyroid hormone receptors may play roles in tissue-specific processes across all of Xenopus development.

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