Noncanonical thyroid hormone signaling mediates cardiometabolic effects in vivo

Thyroid hormone (TH) and TH receptors (TRs) α and β act by binding to TH response elements (TREs) in regulatory regions of target genes. This nuclear signaling is established as the canonical or type 1 pathway for TH action. Nevertheless, TRs also rapidly activate intracellular second-messenger signaling pathways independently of gene expression (noncanonical or type 3 TR signaling). To test the physiological relevance of noncanonical TR signaling, we generated knockin mice with a mutation in the TR DNA-binding domain that abrogates binding to DNA and leads to complete loss of canonical TH action. We show that several important physiological TH effects are preserved despite the disruption of DNA binding of TRα and TRβ, most notably heart rate, body temperature, blood glucose, and triglyceride concentration, all of which were regulated by noncanonical TR signaling. Additionally, we confirm that TRE-binding–defective TRβ leads to disruption of the hypothalamic–pituitary–thyroid axis with resistance to TH, while mutation of TRα causes a severe delay in skeletal development, thus demonstrating tissue- and TR isoform-specific canonical signaling. These findings provide in vivo evidence that noncanonical TR signaling exerts physiologically important cardiometabolic effects that are distinct from canonical actions. These data challenge the current paradigm that in vivo physiological TH action is mediated exclusively via regulation of gene transcription at the nuclear level.

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

Molecular and Cellular Biology ◽

10.1128/mcb.16.1.219 ◽

1996 ◽

Vol 16 (1) ◽

pp. 219-227 ◽

Cited By ~ 12

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.

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Noncanonical Action of Thyroid Hormone Receptors α and β

Experimental and Clinical Endocrinology & Diabetes ◽

10.1055/a-1088-1187 ◽

2020 ◽

Vol 128 (06/07) ◽

pp. 383-387

Author(s):

G. Sebastian Hönes ◽

Daniela Geist ◽

Lars C. Moeller

Keyword(s):

Thyroid Hormone ◽

Dna Binding ◽

Hormone Receptors ◽

Target Genes ◽

Bone Development ◽

Regulation Of Gene Expression ◽

Cardiovascular Effects ◽

Pi3k Pathway ◽

Additional Mode

AbstractThyroid hormone (TH) is essential for the regulation of many physiological processes, especially growth, organ development, energy metabolism and cardiovascular effects. TH acts via the TH receptors (TR) α and β. By binding to thyroid hormone responsive elements (TREs) on the DNA, TRs regulate expression of TH target genes. Thus, TRs are mainly characterized as ligand dependent transcription factors and regulation of gene expression and protein synthesis is considered the canonical mode of TH/TR action. The demonstration that the ligand-bound TRs α and β also mediate activation of the phosphatidylinositol-3-kinase (PI3K) pathway established noncanonical TH/TR action as an additional mode of TH signaling. Recently, TR mutant mouse models allowed to determine the underlying mode of TH/TR action, either canonical or noncanonical TH/TR signaling, for several physiological TH effects in vivo: Regulation of the hypothalamic-pituitary-thyroid axis requires DNA-binding of TRβ, whereas hepatic triglyceride content appears to be regulated by noncanonical TRβ signaling. TRα mediated effects in bone development are dependent on DNA-binding, whereas several cardiovascular TRα effects are rapid and independent from DNA-binding. Therefore, noncanonical TH/TR action contributes to the overall effects of TH in physiology.

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Genome-Wide Binding Analyses of HOXB1 Revealed a Novel DNA Binding Motif Associated with Gene Repression

Journal of Developmental Biology ◽

10.3390/jdb9010006 ◽

2021 ◽

Vol 9 (1) ◽

pp. 6

Author(s):

Narendra Pratap Singh ◽

Bony De Kumar ◽

Ariel Paulson ◽

Mark E. Parrish ◽

Carrie Scott ◽

...

Keyword(s):

Dna Binding ◽

Target Genes ◽

Embryonic Stem ◽

Binding Motif ◽

Binding Assays ◽

Histone Marks ◽

Genome Wide ◽

Hox Cofactors

Knowledge of the diverse DNA binding specificities of transcription factors is important for understanding their specific regulatory functions in animal development and evolution. We have examined the genome-wide binding properties of the mouse HOXB1 protein in embryonic stem cells differentiated into neural fates. Unexpectedly, only a small number of HOXB1 bound regions (7%) correlate with binding of the known HOX cofactors PBX and MEIS. In contrast, 22% of the HOXB1 binding peaks display co-occupancy with the transcriptional repressor REST. Analyses revealed that co-binding of HOXB1 with PBX correlates with active histone marks and high levels of expression, while co-occupancy with REST correlates with repressive histone marks and repression of the target genes. Analysis of HOXB1 bound regions uncovered enrichment of a novel 15 base pair HOXB1 binding motif HB1RE (HOXB1 response element). In vitro template binding assays showed that HOXB1, PBX1, and MEIS can bind to this motif. In vivo, this motif is sufficient for direct expression of a reporter gene and over-expression of HOXB1 selectively represses this activity. Our analyses suggest that HOXB1 has evolved an association with REST in gene regulation and the novel HB1RE motif contributes to HOXB1 function in part through a repressive role in gene expression.

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Thyroid hormones and fetal neurological development

Journal of Endocrinology ◽

10.1530/joe-10-0444 ◽

2011 ◽

Vol 209 (1) ◽

pp. 1-8 ◽

Cited By ~ 116

Author(s):

J Patel ◽

K Landers ◽

H Li ◽

R H Mortimer ◽

K Richard

Keyword(s):

Thyroid Hormone ◽

Cell Membrane ◽

Hormone Receptors ◽

Developmental Stages ◽

Fetal Brain ◽

Neurological Development ◽

Thyroid Hormone Metabolism ◽

Pituitary Thyroid Axis ◽

Fetal Thyroid ◽

Type 3

The development of fetal thyroid function is dependent on the embryogenesis, differentiation, and maturation of the thyroid gland. This is coupled with evolution of the hypothalamic–pituitary–thyroid axis and thyroid hormone metabolism, resulting in the regulation of thyroid hormone action, production, and secretion. Throughout gestation there is a steady supply of maternal thyroxine (T4) which has been observed in embryonic circulation as early as 4 weeks post-implantation. This is essential for normal early fetal neurogenesis. Triiodothyronine concentrations remain very low during gestation due to metabolism via placental and fetal deiodinase type 3. T4 concentrations are highly regulated to maintain low concentrations, essential for protecting the fetus and reaching key neurological sites such as the cerebral cortex at specific developmental stages. There are many known cell membrane thyroid hormone transporters in fetal brain that play an essential role in regulating thyroid hormone concentrations in key structures. They also provide the route for intracellular thyroid hormone interaction with associated thyroid hormone receptors, which activate their action. There is a growing body of experimental evidence from rats and humans to suggest that even mild maternal hypothyroxinemia may lead to abnormalities in fetal neurological development. Our review will focus on the ontogeny of thyroid hormone in fetal development, with a focus on cell membrane transporters and TR action in the brain.

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The TRH Gene Is Regulated by Thyroid Hormone at the Level of Transcription in Vivo

Endocrine Reviews ◽

10.1210/edrv.31.1.9994 ◽

2010 ◽

Vol 31 (1) ◽

pp. 136-136

Author(s):

Michelle L. Sugrue ◽

Kristen R. Vella ◽

Crystal Morales ◽

Marisol E. Lopez ◽

Anthony N. Hollenberg

Keyword(s):

Thyroid Hormone ◽

Genomic Region ◽

Model System ◽

Model Systems ◽

In Vivo Model ◽

Pituitary Thyroid Axis ◽

Thyroid Axis ◽

Normal Production

ABSTRACT The expression of the TRH gene in the paraventricular nucleus (PVH) of the hypothalamus is required for the normal production of thyroid hormone (TH) in rodents and humans. In addition, the regulation of TRH mRNA expression by TH, specifically in the PVH, ensures tight control of the set point of the hypothalamic-pituitary-thyroid axis. Although many studies have assumed that the regulation of TRH expression by TH is at the level of transcription, there is little data available to demonstrate this. We used two in vivo model systems to show this. In the first model system, we developed an in situ hybridization (ISH) assay directed against TRH heteronuclear RNA to measure TRH transcription directly in vivo. We show that in the euthyroid state, TRH transcription is present both in the PVH and anterior/lateral hypothalamus. In the hypothyroid state, transcription is activated in the PVH only and can be shut off within 5 h by TH. In the second model system, we employed transgenic mice that express the Cre recombinase under the control of the genomic region containing the TRH gene. Remarkably, TH regulates Cre expression in these mice in the PVH only. Taken together, these data affirm that TH regulates TRH at the level of transcription in the PVH only and that genomic elements surrounding the TRH gene mediate its regulation by T3. Thus, it should be possible to identify the elements within the TRH locus that mediate its regulation by T3 using in vivo approaches.

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In Vivo Activity of the Thyroid Hormone Receptor β- and α-Selective Agonists GC-24 and CO23 on Rat Liver, Heart, and Brain

Endocrinology ◽

10.1210/en.2010-0813 ◽

2011 ◽

Vol 152 (3) ◽

pp. 1136-1142 ◽

Cited By ~ 25

Author(s):

Carmen Grijota-Martínez ◽

Eric Samarut ◽

Thomas S. Scanlan ◽

Beatriz Morte ◽

Juan Bernal

Keyword(s):

Thyroid Hormone ◽

Hormone Receptor ◽

Target Genes ◽

Thyroid Hormone Receptor ◽

Receptor Subtype ◽

Receptor Subtypes ◽

Genetic Modifications ◽

Hormone Analogs ◽

Thyroid Hormone Receptor Β

Thyroid hormone analogs with selective actions through specific thyroid hormone receptor (TR) subtypes are of great interest. They might offer the possibility of mimicking physiological actions of thyroid hormone with receptor subtype or tissue specificity with therapeutic aims. They are also pharmacological tools to dissect biochemical pathways mediated by specific receptor subtypes, in a complementary way to mouse genetic modifications. In this work, we studied the in vivo activity in developing rats of two thyroid hormone agonists, the TRβ-selective GC-24 and the TRα-selective CO23. Our principal goal was to check whether these compounds were active in the rat brain. Analog activity was assessed by measuring the expression of thyroid hormone target genes in liver, heart, and brain, after administration to hypothyroid rats. GC-24 was very selective for TRβ and lacked activity on the brain. On the other hand, CO23 was active in liver, heart, and brain on genes regulated by either TRα or TRβ. This compound, previously shown to be TRα-selective in tadpoles, displayed no selectivity in the rat in vivo.

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Differential Contribution of N- and C-Terminal Regions of HIF1α and HIF2α to Their Target Gene Selectivity

International Journal of Molecular Sciences ◽

10.3390/ijms21249401 ◽

2020 ◽

Vol 21 (24) ◽

pp. 9401

Author(s):

Antonio Bouthelier ◽

Florinda Meléndez-Rodríguez ◽

Andrés A. Urrutia ◽

Julián Aragonés

Keyword(s):

Transcription Factors ◽

Dna Binding ◽

Cellular Response ◽

Target Gene ◽

Target Genes ◽

Transactivation Domain ◽

Transactivation Domains ◽

Relative Contribution

Cellular response to hypoxia is controlled by the hypoxia-inducible transcription factors HIF1α and HIF2α. Some genes are preferentially induced by HIF1α or HIF2α, as has been explored in some cell models and for particular sets of genes. Here we have extended this analysis to other HIF-dependent genes using in vitro WT8 renal carcinoma cells and in vivo conditional Vhl-deficient mice models. Moreover, we generated chimeric HIF1/2 transcription factors to study the contribution of the HIF1α and HIF2α DNA binding/heterodimerization and transactivation domains to HIF target specificity. We show that the induction of HIF1α-dependent genes in WT8 cells, such as CAIX (CAR9) and BNIP3, requires both halves of HIF, whereas the HIF2α transactivation domain is more relevant for the induction of HIF2 target genes like the amino acid carrier SLC7A5. The HIF selectivity for some genes in WT8 cells is conserved in Vhl-deficient lung and liver tissue, whereas other genes like Glut1 (Slc2a1) behave distinctly in these tissues. Therefore the relative contribution of the DNA binding/heterodimerization and transactivation domains for HIF target selectivity can be different when comparing HIF1α or HIF2α isoforms, and that HIF target gene specificity is conserved in human and mouse cells for some of the genes analyzed.

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The role of thyroid hormone receptor DNA binding in negative thyroid hormone-mediated gene transcription

Journal of Molecular Endocrinology ◽

10.1677/jme-08-0023 ◽

2008 ◽

Vol 41 (1) ◽

pp. 25-34 ◽

Cited By ~ 6

Author(s):

Anne Wulf ◽

Marianne G Wetzel ◽

Maxim Kebenko ◽

Meike Kröger ◽

Angelika Harneit ◽

...

Keyword(s):

Thyroid Hormone ◽

Dna Binding ◽

Gene Transcription ◽

Hormone Receptor ◽

Target Genes ◽

Thyroid Hormone Receptor ◽

Point Mutations ◽

Chimeric Protein ◽

Functional Consequences ◽

Glycerol 3 Phosphate Dehydrogenase

Thyroid hormone 3,3′,5-tri-iodothyronine (T3) regulates gene expression in a positive and negative manner. Here, we analyzed the regulation of a positively (mitochondrial glycerol-3-phosphate dehydrogenase) and negatively T3-regulated target gene (TSHα). Thyroid hormone receptor (TR) activates mGPDH but not TSH promoter fragments in a mammalian one-hybrid assay. Furthermore, we investigated functional consequences of targeting TR to DNA independent of its own DNA-binding domain (DBD). Using a chimeric fusion protein of the DBD of yeast transcription factor Gal4 with TR, we demonstrated a positive regulation of gene transcription in response to T3. T3-mediated activation of this chimeric protein is further increased after an introduction of point mutations within the DBD of TR. Moreover, we investigated the capacity of TR to negatively regulate gene transcription on a DNA-tethered cofactor platform. A direct binding of TR to DNA via its own DBD is dispensable in this assay. We investigated functional consequences of point mutations affecting different domains of TR. Our data indicate that the DBD of TR plays a key role in direct DNA binding on positively but not on negatively T3-regulated target genes. Nevertheless, the DBD is involved in mediating negative gene regulation independent of its capacity to bind DNA.

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Transgenic Analysis Reveals that Thyroid Hormone Receptor Is Sufficient To Mediate the Thyroid Hormone Signal in Frog Metamorphosis

Molecular and Cellular Biology ◽

10.1128/mcb.24.20.9026-9037.2004 ◽

2004 ◽

Vol 24 (20) ◽

pp. 9026-9037 ◽

Cited By ~ 96

Author(s):

Daniel R. Buchholz ◽

Akihiro Tomita ◽

Liezhen Fu ◽

Bindu D. Paul ◽

Yun-Bo Shi

Keyword(s):

Thyroid Hormone ◽

Hormone Receptor ◽

Target Genes ◽

Thyroid Hormone Receptor ◽

Gene Activation ◽

Inducible Promoter ◽

Vertebrate Development ◽

Transcription System

ABSTRACT Thyroid hormone (T3) has long been known to be important for vertebrate development and adult organ function. Whereas thyroid hormone receptor (TR) knockout and transgenic studies of mice have implicated TR involvement in mammalian development, the underlying molecular bases for the resulting phenotypes remain to be determined in vivo, especially considering that T3 is known to have both genomic, i.e., through TRs, and nongenomic effects on cells. Amphibian metamorphosis is an excellent model for studying the role of TR in vertebrate development because of its total dependence on T3. Here we investigated the role of TR in metamorphosis by developing a dominant positive mutant thyroid hormone receptor (dpTR). In the frog oocyte transcription system, dpTR bound a T3-responsive promoter and activated the promoter independently of T3. Transgenic expression of dpTR under the control of a heat shock-inducible promoter in premetamorphic tadpoles led to precocious metamorphic transformations. Molecular analyses showed that dpTR induced metamorphosis by specifically binding to known T3 target genes, leading to increased local histone acetylation and gene activation, similar to T3-bound TR during natural metamorphosis. Our experiments indicated that the metamorphic role of T3 is through genomic action of the hormone, at least on the developmental parameters tested. They further provide the first example where TR is shown to mediate directly and sufficiently these developmental effects of T3 in individual organs by regulating target gene expression in these organs.

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Spermatogonial Type 3 Deiodinase Regulates Thyroid Hormone Target Genes in Developing Testicular Somatic Cells

Endocrinology ◽

10.1210/en.2019-00259 ◽

2019 ◽

Vol 160 (12) ◽

pp. 2929-2945

Author(s):

M Elena Martinez ◽

Christine W Lary ◽

Aldona A Karaczyn ◽

Michael D Griswold ◽

Arturo Hernandez

Keyword(s):

Gene Expression ◽

Thyroid Hormone ◽

Target Genes ◽

Somatic Cells ◽

Published Data ◽

Data Sets ◽

Testicular Cells ◽

Differentiation And Proliferation ◽

Neonatal Testis ◽

Type 3

Abstract Premature overexposure to thyroid hormone causes profound effects on testis growth, spermatogenesis, and male fertility. We used genetic mouse models of type 3 deiodinase (DIO3) deficiency to determine the genetic programs affected by premature thyroid hormone action and to define the role of DIO3 in regulating thyroid hormone economy in testicular cells. Gene expression profiling in the neonatal testis of DIO3-deficient mice identified 5699 differentially expressed genes. Upregulated and downregulated genes were, respectively, involved according to DAVID analysis with cell differentiation and proliferation. They included anti-Müllerian hormone and genes involved in the formation of the blood–testis barrier, which are specific to Sertoli cells (SCs). They also included steroidogenic genes, which are specific to Leydig cells. Comparison with published data sets of genes enriched in SCs and spermatogonia, and responsive to retinoic acid (RA), identified a subset of genes that were regulated similarly by RA and thyroid hormone. This subset of genes showed an expression bias, as they were downregulated when enriched in spermatogonia and upregulated when enriched in SCs. Furthermore, using a genetic approach, we found that DIO3 is not expressed in SCs, but spermatogonia-specific inactivation of DIO3 led to impaired testis growth, reduced SC number, decreased cell proliferation and, especially during neonatal development, altered gene expression specific to somatic cells. These findings indicate that spermatogonial DIO3 protects testicular cells from untimely thyroid hormone signaling and demonstrate a mechanism of cross-talk between somatic and germ cells in the neonatal testis that involves the regulation of thyroid hormone availability and action.

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