Thyroid Hormone Receptor Beta Research Articles

Genomic instability and proliferation/survival pathways in RB1-deficient malignancies.

Genomic instability (GIN) is a hallmark of most cancer cells. However, compared to most human cancer cell types, the retinoblastoma tumor cells show a relatively stable genome. The fundamental basis of this genomic stability has yet to be elucidated, and the role of certain proteins involved in cell cycle regulation may be the key to the development of these specific genotypes. We examined whether thyroid hormone receptor beta 1 and 2 (TRβ1 and TRβ2), known to regulate tumorigenesis, and PTTG1, a mitotic checkpoint protein, play a role in maintaining genomic stability in retinoblastoma. In order to elucidate the role of these proteins in development of aneuploidy/polyploidy, an indicator of GIN, we first studied comparative GIN in retinoblastomas and multiple RB mutant cancer cell lines using single nucleotide polymorphism (SNP) analysis. We then utilized pLKO lentiviral vectors to selectively modify expression of the targeted cell cycle proteins and interpret their effect on downstream cell cycle proteins and their relative effects on the development of polyploidy in multiple tumor cell lines. The SNP analysis showed that retinoblastomas displayed relatively fewer genomic copy number changes as compared to other RB1-deficient cancer cell lines. Both TRβ1 and TRβ2 knockdown led to accumulation of E2F1 and PTTG1 and increased GIN as demonstrated by an increase in polyploidy. Downregulation of PTTG1 led to a relative decrease in GIN while upregulation of PTTG1 led to a relative increase in GIN. Knockdown of E2F1 led to a downstream decrease in PTTG1 expression. Rb-knockdown also upregulated E2F1 and PTTG1 leading to increased GIN. We showed that Rb is necessary for PTTG1 inhibition and genomic stability. A relatively stable genome in retinoblastoma tumor cells is maintained by TRβ1 and TRβ2-mediated PTTG1 inhibition, counteracting Rb-deficiency-related GIN. TRβ1, TRβ2 and Rb-KD all led to the downstream PTTG1 accumulation, apparently through an activation of E2F1 resulting in extensive genomic instability as seen in other Rb-deficient tumors.

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

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.

Neonatal “resistance to thyroid hormone (refetoff syndrome)” with novel THRB mutation

Context: Resistance to thyroid hormone (RTH) is an inherited condition with variable target tissue hyposensitivity. We report two cases of preterm neonates with Neonatal resistance to thyroid hormone syndrome, one with a novel mutation in the “Thyroid hormone receptor – Beta (THRB) gene. Case description: Case 1: A male extremely preterm neonate born at 25 weeks and birth weight of 647 grams. The routine newborn screen raised concerns for hypothyroidism and further labs revealed persistently elevated TSH, free T4. The thyroid antibodies were not elevated. MRI brain did not show a pituitary tumor. The baby had persistent tachycardia and poor weight gain. The baby died eventually due to late onset sepsis as a complication of prematurity at 6 weeks of life. DNA sequence testing revealed that one of the copies had c.1299delC mutation in the THRB gene which is predicted to be pathogenic but not reported in literature. Case 2: A very preterm baby girl born at 30 weeks investigated for thyroid dysfunction due to persistent tachycardia and as mother had recently been diagnosed with resistance to thyroid hormone showed Heterozygous positive for p.PRO453THR mutation in THRB gene. Conclusion: This is the first case report of resistance to TH in extremely/very preterm newborn and one of them with novel mutation, suggesting tissue level differential functional thyroid status. Both these heterozygous mutations affect both THRB1 and THRB2 as exon 10 is necessary for both the protein isoforms. With TSH and T4 being elevated and persistent tachycardia, we think that these newborns had “Pituitary specific RTH”.

Thyroid hormone resistance misdiagnosed as Graves' disease

Resistance to thyroid hormone (RTH) syndrome is a very rare disorder characterized by mutations of the thyroid hormone receptor beta and is usually inherited as an autosomal dominant trait. Patients with RTH are usually euthyroid but rarely may present with signs and symptoms consistent with hyperthyroidism. Here, we describe the case of a young girl with goiter who was previously misdiagnosed to have hyperthyroidism and was subsequently diagnosed to be suffering from RTH.

An evaluation of the endocrine disruptive potential of crude oil water accommodated fractions and crude oil contaminated surface water to freshwater organisms using in vitro and in vivo approaches.

Knowledge regarding the potential impacts of crude oil on endocrine signaling in freshwater aquatic vertebrates is limited. The expression of selected genes as biomarkers for altered endocrine signaling was studied in African clawed frog, Xenopus laevis, tadpoles and juvenile Mozambique tilapia, Oreochromis mossambicus, exposed to weathered bunker and unweathered refinery crude oil water accommodated fractions (WAFs). In addition, the expression of the aforementioned genes was quantified in X. laevis tadpoles exposed to surface water collected from the proximity of an underground oil bunker. The (anti)estrogenicity and (anti)androgenicity of crude oil, crude oil WAFs, and surface water were furthermore evaluated using recombinant yeast. Thyroid hormone receptor beta expression was significantly down-regulated in X. laevis in response to both oil WAF types, whereas a further thyroid linked gene, type 2 deiodinase, was up-regulated in O. mossambicus exposed to a high concentration of bunker oil WAF. In addition, both WAFs altered the expression of the adipogenesis-linked peroxisome proliferator-activated receptor gamma in X. laevis. The crude oil and WAFs exhibited antiestrogenic and antiandrogenic activity in vitro. However, O. mossambicus androgen receptor 2 was the only gene, representing the reproductive system, significantly affected by WAF exposure. Estrogenicity, antiestrogenicity, and antiandrogenicity were detected in surface water samples; however, no significant changes were observed in the expression of any of the genes evaluated in X. laevis exposed to surface water. The responses varied among the 2 model organisms used, as well as among the 2 types of crude oil. Nonetheless, the data provide evidence that crude oil pollution may lead to adverse health effects in freshwater fish and amphibians as a result of altered endocrine signaling. Environ Toxicol Chem 2017;36:1330-1342. © 2016 SETAC.

MicroRNA 200a inhibits erythroid differentiation by targeting PDCD4 and THRB.

Previous studies on erythropoiesis revealed that microRNAs (miRNAs) play a critical role in erythroid differentiation. Given the abundance of identified miRNAs and the limited understanding of erythroid miRNAs, additional examination is required. Here, two sets of erythroid differentiation miRNome data were analysed to screen for novel erythroid-inhibiting miRNAs. MIR200A was selected based on its pattern of downregulated expression in the miRNome datasets during induction of erythroid differentiation. Overexpression of MIR200A in K562 and TF-1 cells confirmed its inhibitory role in erythroid differentiation. Further invivo study indicated that overexpression of mir200a inhibited primitive erythropoiesis of zebrafish. Transcriptome analyses after MIR200A overexpression in TF-1 cells indicated a significant role in regulating erythroid function and revealed potential regulation networks. Additionally, bioinformatics and experimental analyses confirmed that PDCD4 (programmed cell death 4) and THRB (thyroid hormone receptor, beta) are both targets of MIR200A-3p. Gain- and loss-of-function studies of PDCD4 and THRB revealed that the two targets were capable of promoting erythroid gene expression. Overall, our results revealed that microRNA 200a inhibits erythroid differentiation by targeting PDCD4 and THRB.

Innapropriate TSH secretion: the challenging diagnosis

Background. The elevation of thyroid hormone with a normal or elevated TSH occurs uncommonly. This has different causes and pose a diagnosis challenge namely between TSH-secreting pituitary adenoma (TSHoma) and resistance to thyroid hormone. The accurate diagnosis is essential, because delayed diagnosis of TSHoma can lead to tumour growth and poor surgical cure rates, whereas medical, surgical or radioablative treatments in patients with resistance to thyroid hormone are usually unnecessary and potentially harmful.Case Report. A 23-years-old women with palpitations, fatigue, insomnia and exophthalmia with elevated serum free T4 and TSH, medicated with methimazole 5mg 3id was sent to evaluation in endocrinology department. She did not report headaches or visual problems. Patient’s laboratory tests at admission: TSH 9,6 µUI/mL (0,4–4,0 µUI/mL), Free T4 2,1 pg/dL (0,8–1,9 pg/dL). After stopping anti-thyroid drug presented TSH 2,9 µUI/mL (0,4-4,0 µUI/mL), Free T4 3,7 pg/dL (0,8–1,9 pg/dL), Free T3 11 pg/mL (1,8–4,2 pg/mL); antithyroid peroxidase and antithyroglobulin antibodies and thyroid stimulating immunoglobulin were undetectable; thyroid ultrasound revealed small heterogeneous goiter; thyroid technetium scintigraphy showed diffuse glandular hyperfunctioning; Magnetic resonance imaging revealed a microadenoma with 7,5mm in the left side of pituitary. Remaining anterior pituitary hormones were within normal ranges. The thyrotropin-releasing hormone stimulation test was performed and revealed TSH at 0’ 1,7 µUI/mL, 20’ 14 µUI/mL and 60’ 11 µUI/mL, with free T4 2,3 pg/dL and free T3 5,9 pg/mL, which was consistent with thyroid hormone resistance syndrome. In this clinical setting genetic test was performed and revealed mutation in heterozygosity in THRβ gene: c.1030G>A, p.Gly344Arg. Patient’s mother was also tested and no mutation was found. Her father was not available to do the genetic test. No pituitary surgery or thyroidectomy was performed, nor were prescribed any anti-thyroid drugs.Conclusions. In this case, an innapropriate TSH secretion was identified and the clinical, biochemical and genetic investigations were consistent with resistance to thyroid hormone. Known that as many as 15% non-ill people may have a small, nonfunctioning pituitary adenoma, patients with thyroid hormone resistance may have incidentally abnormal imaging findings. The high level of clinical suspicion and the proper laboratory, genetic and radiological studies, conduct to a correct diagnosis and prevent unnecessary and potential harmful therapies.

Implication of thyroid hormone signaling in neural crest cells migration: Evidence from thyroid hormone receptor beta knockdown and NH3 antagonist studies

Thyroid hormones (TH) have been mainly associated with post-embryonic development and adult homeostasis but few studies report direct experimental evidence for TH function at very early phases of embryogenesis.We assessed the outcome of altered TH signaling on early embryogenesis using the amphibian Xenopus as a model system. Precocious exposure to the TH antagonist NH-3 or impaired thyroid receptor beta function led to severe malformations related to neurocristopathies. These include pathologies with a broad spectrum of organ dysplasias arising from defects in embryonic neural crest cell (NCC) development. We identified a specific temporal window of sensitivity that encompasses the emergence of NCCs. Although the initial steps in NCC ontogenesis appeared unaffected, their migration properties were severely compromised both in vivo and in vitro. Our data describe a role for TH signaling in NCCs migration ability and suggest severe consequences of altered TH signaling during early phases of embryonic development.

Detection of genomic signatures of recent selection in commercial broiler chickens.

BackgroundIdentification of the genomic signatures of recent selection may help uncover causal polymorphisms controlling traits relevant to recent decades of selective breeding in livestock. In this study, we aimed at detecting signatures of recent selection in commercial broiler chickens using genotype information from single nucleotide polymorphisms (SNPs). A total of 565 chickens from five commercial purebred lines, including three broiler sire (male) lines and two broiler dam (female) lines, were genotyped using the 60K SNP Illumina iSelect chicken array. To detect genomic signatures of recent selection, we applied two methods based on population comparison, cross-population extended haplotype homozygosity (XP-EHH) and cross-population composite likelihood ratio (XP-CLR), and further analyzed the results to find genomic regions under recent selection in multiple purebred lines.ResultsA total of 321 candidate selection regions spanning approximately 1.45 % of the chicken genome in each line were detected by consensus of results of both XP-EHH and XP-CLR methods. To minimize false discovery due to genetic drift, only 42 of the candidate selection regions that were shared by 2 or more purebred lines were considered as high-confidence selection regions in the study. Of these 42 regions, 20 were 50 kb or less while 4 regions were larger than 0.5 Mb. In total, 91 genes could be found in the 42 regions, among which 19 regions contained only 1 or 2 genes, and 9 regions were located at gene deserts.ConclusionsOur results provide a genome-wide scan of recent selection signatures in five purebred lines of commercial broiler chickens. We found several candidate genes for recent selection in multiple lines, such as SOX6 (Sex Determining Region Y-Box 6) and cTR (Thyroid hormone receptor beta). These genes may have been under recent selection due to their essential roles in growth, development and reproduction in chickens. Furthermore, our results suggest that in some candidate regions, the same or opposite alleles have been under recent selection in multiple lines. Most of the candidate genes in the selection regions are novel, and as such they should be of great interest for future research into the genetic architecture of traits relevant to modern broiler breeding.Electronic supplementary materialThe online version of this article (doi:10.1186/s12863-016-0430-1) contains supplementary material, which is available to authorized users.

Novel cell-based assay for detection of thyroid receptor beta-interacting environmental contaminants.

Even though the presence of endocrine disrupting chemicals (EDCs) with thyroid hormone (TH)-like activities in the environment is a major health concern, the methods for their efficient detection and monitoring are still limited. Here we describe a novel cell assay, based on the translocation of a green fluorescent protein (GFP)-tagged chimeric molecule of glucocorticoid receptor (GR) and the thyroid receptor beta (TRβ) from the cytoplasm to the nucleus in the presence of TR ligands. Unlike the constitutively nuclear TRβ, this GFP-GR-TRβ chimera is cytoplasmic in the absence of hormone while translocating to the nucleus in a time- and concentration-dependent manner upon stimulation with triiodothyronine (T3) and thyroid hormone analogue, TRIAC, while the reverse triiodothyronine (3,3',5'-triiodothyronine, or rT3) was inactive. Moreover, GFP-GR-TRβ chimera does not show any cross-reactivity with the GR-activating hormones, thus providing a clean system for the screening of TR beta-interacting EDCs. Using this assay, we demonstrated that Bisphenol A (BPA) and 3,3',5,5'-Tetrabromobisphenol (TBBPA) induced GFP-GR-TRβ translocation at micro molar concentrations. We screened over 100 concentrated water samples from different geographic locations in the United States and detected a low, but reproducible contamination in 53% of the samples. This system provides a novel high-throughput approach for screening for endocrine disrupting chemicals (EDCs) interacting with TR beta.

Resistencia a hormonas tiroideas: sospecha de una nueva mutación en el gen rTHβ

Resistance to thyroid hormone, described by Refetoff in 1967, it is an autosomic dominant genetic disorder. It is characterised by a reduced soft-tissue response to thyroid hormone action, associated with increased free thyroxin (FT4) levels with no thyrotrophic hormone inhibition, as a consequence of mutations present in thyroid hormone receptor beta gen (rTHβ) in 85% of cases. It is a rare disease and the definitive diagnostic is based on a genetic study.A report is presented on a possible new mutation case of the rTHβ gene.

Combined effects of transferrin and thyroid hormone during oligodendrogenesis In vitro.

Thyroid hormones (THs) and transferrin (Tf) are factors capable of favoring myelination due to their positive effects on oligodendroglial cell (OLG) differentiation. The first notion of a combined effect of apotransferrin (aTf) and TH emerged from experiments conducted in young hyperthyroid animals, which showed a seven-fold increase in the expression of Tf mRNA and precocious myelination when compared with control animals. The mechanism underlying this phenomenon in young hyperthyroid rats could consist of an increase in Tf synthesis, which in the CNS is almost exclusively produced by OLG. Overall, our results show that, during the initial stages of OLG differentiation, Tf synthesis triggers thyroid hormone receptor alpha 1 (TRα1) expression in the subventricular zone (SVZ) and promotes proliferating cells to become responsive to this trophic factor. Exposure to TH could then regulate Tf expression through TRα1 and promote the induction of thyroid hormone receptor beta (TRβ) expression, which mediates TH effects on myelination through the activation of final OLG differentiation. This regulation of the combined effects of Tf and THs implies that both factors are fundamental actors during oligodendrogenesis. GLIA 2016;64:1879-1891.

Metabolic engineering of Corynebacterium glutamicum for methionine production by removing feedback inhibition and increasing NADPH level.

Relieving the feedback inhibition of key enzymes in a metabolic pathway is frequently the first step of producer-strain construction by genetic engineering. However, the strict feedback regulation exercised by microorganisms in methionine biosynthesis often makes it difficult to produce methionine at a high level. In this study, Corynebacterium glutamicum ATCC 13032 was metabolically engineered for methionine production. First, the metD gene encoding the methionine uptake system was deleted to achieve extracellular accumulation of methionine. Then, random mutagenesis was performed to remove feedback inhibition by metabolic end-products. The resulting strain C. glutamicum ENM-16 was further engineered to block or decrease competitive branch pathways by deleting the thrB gene and changing the start codon of the dapA gene, followed by point mutations of lysC (C932T) and pyc (G1A, C1372T) to increase methionine precursor supply. To enrich the NADPH pool, glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase in the pentose phosphate pathway were mutated to reduce their sensitivity to inhibition by intracellular metabolites. The resultant strain C. glutamicum LY-5 produced 6.85±0.23gmethioninel(-1) with substrate-specific yield (Y P/S) of 0.08mol per mol of glucose after 72h fed-batch fermentation. The strategies described here will be useful for construction of methionine engineering strains.

A Novel Method for Gene-Specific Enhancement of Protein Translation by Targeting 5’UTRs of Selected Tumor Suppressors

BackgroundTranslational control is a mechanism of protein synthesis regulation emerging as an important target for new therapeutics. Naturally occurring microRNAs and synthetic small inhibitory RNAs (siRNAs) are the most recognized regulatory molecules acting via RNA interference. Surprisingly, recent studies have shown that interfering RNAs may also activate gene transcription via the newly discovered phenomenon of small RNA-induced gene activation (RNAa). Thus far, the small activating RNAs (saRNAs) have only been demonstrated as promoter-specific transcriptional activators.FindingsWe demonstrate that oligonucleotide-based trans-acting factors can also specifically enhance gene expression at the level of protein translation by acting at sequence-specific targets within the messenger RNA 5’-untranslated region (5’UTR). We designed a set of short synthetic oligonucleotides (dGoligos), specifically targeting alternatively spliced 5’UTRs in transcripts expressed from the THRB and CDKN2A suppressor genes. The in vitro translation efficiency of reporter constructs containing alternative TRβ1 5’UTRs was increased by up to more than 55-fold following exposure to specific dGoligos. Moreover, we found that the most folded 5’UTR has higher translational regulatory potential when compared to the weakly folded TRβ1 variant. This suggests such a strategy may be especially applied to enhance translation from relatively inactive transcripts containing long 5’UTRs of complex structure.SignificanceThis report represents the first method for gene-specific translation enhancement using selective trans-acting factors designed to target specific 5’UTR cis-acting elements. This simple strategy may be developed further to complement other available methods for gene expression regulation including gene silencing. The dGoligo-mediated translation-enhancing approach has the potential to be transferred to increase the translation efficiency of any suitable target gene and may have future application in gene therapy strategies to enhance expression of proteins including tumor suppressors.

Coexistence of resistance to thyroid hormone and papillary thyroid carcinoma.

SummaryResistance to thyroid hormone (RTH) is a syndrome of reduced tissue responsiveness to thyroid hormones. RTH is majorly caused by mutations in the thyroid hormone receptor beta (THRB) gene. Recent studies indicated a close association of THRB mutations with human cancers, but the role of THRB mutation in carcinogenesis is still unclear. Here, we report a rare case of RTH with a papillary thyroid carcinoma (PTC). A 26-year-old woman was referred to our hospital due to a thyroid tumor and hormonal abnormality. She had elevated serum thyroid hormones and non-suppressed TSH levels. Genetic analysis of THRB identified a missense mutation, P452L, leading to a diagnosis of RTH. Ultrasound-guided fine-needle aspiration biopsy of the tumor and lymph nodes enabled the cytological diagnosis of PTC with lymph node metastases. Total thyroidectomy and neck lymph nodes dissection were performed. Following surgery, thyroxine replacement (≥500 μg) was necessary to avoid the symptoms of hypothyroidism and to maintain her TSH levels within the same range as before the operation. During the follow-up, basal thyroglobulin (Tg) levels were around 6 ng/ml and TSH-stimulated Tg levels were between 12 and 20 ng/ml. Up to present, the patient has had no recurrence of PTC. This indicates that these Tg values are consistent with a biochemical incomplete response or an indeterminate response. There is no consensus regarding the management of thyroid carcinoma in patients with RTH, but aggressive treatments such as total thyroidectomy followed by radioiodine (RAI) and TSH suppression therapy are recommended.Learning pointsThere are only a few cases reporting the coexistence of RTH and thyroid carcinoma. Moreover, our case would be the first case presenting one with lymph node metastases.Recent studies indicated a close association of THRB mutations with human cancers, but the role of THRB mutation in carcinogenesis is still unclear.When total thyroidectomy is performed in patients with RTH, a large amount of thyroxine is needed to maintain their thyroid function.There is no consensus regarding the management of thyroid carcinoma in patient with RTH, but effective treatments such as total thyroidectomy followed by RAI and TSH suppression therapy are recommended.

3,5-Diiodothyronine-mediated transrepression of the thyroid hormone receptor beta gene in tilapia. Insights on cross-talk between the thyroid hormone and cortisol signaling pathways

T3 and cortisol activate or repress gene expression in virtually every vertebrate cell mainly by interacting with their nuclear hormone receptors. In contrast to the mechanisms for hormone gene activation, the mechanisms involved in gene repression remain elusive. In teleosts, the thyroid hormone receptor beta gene or thrb produces two isoforms of TRβ1 that differ by nine amino acids in the ligand-binding domain of the long-TRβ1, whereas the short-TRβ1 lacks the insert. Previous reports have shown that the genomic effects exerted by 3,5-T2, a product of T3 outer-ring deiodination, are mediated by the long-TRβ1. Furthermore, 3,5-T2 and T3 down-regulate the expression of long-TRβ1 and short-TRβ1, respectively. In contrast, cortisol has been shown to up-regulate the expression of thrb. To understand the molecular mechanisms for thrb modulation by thyroid hormones and cortisol, we used an in silico approach to identify thyroid- and cortisol-response elements within the proximal promoter of thrb from tilapia. We then characterized the identified response elements by EMSA and correlated our observations with the effects of THs and cortisol upon expression of thrb in tilapia. Our data show that 3,5-T2 represses thrb expression and impairs its up-regulation by cortisol possibly through a transrepression mechanism. We propose that for thrb down-regulation, ligands other than T3 are required to orchestrate the pleiotropic effects of thyroid hormones in vertebrates.

Evidence that diclofenac and celecoxib are thyroid hormone receptor beta antagonists

Long term use of NSAIDs is linked to side effects such as gastric bleeding and myocardial infarction. AimsUse of in silico methods and pharmacology to investigate the potential for NSAIDs diclofenac, celecoxib and naproxen to bind to nuclear receptors. Materials and methodsIn silico screening predicted that both diclofenac and celecoxib has the potential to bind to a number of different nuclear receptors; docking analysis confirmed a theoretical ability for diclofenac and celecoxib but not naproxen to bind to TRβ. Key findingsResults from TRβ luciferase reporter assays confirmed that both diclofenac and celecoxib display TRβ antagonistic properties; celecoxib, IC50 3.6×10−6M, and diclofenac IC50 5.3×10−6M, comparable to the TRβ antagonist MLS (IC50 3.1×10−6M). In contrast naproxen, a cardio-sparing NSAID, lacked TRβ antagonist effects. In order to determine the effects of NSAIDs in whole organ in vitro, we used isometric wire myography to measure the changes to Triiodothyronine (T3) induced vasodilation of rat mesenteric arteries. Incubation of arteries in the presence of the TRβ antagonist MLS000389544 (10−5M), as well as diclofenac (10−5M) and celecoxib (10−5M) but not naproxen significantly inhibited T3 induced vasodilation compared to controls. SignificanceThese results highlight the benefits of computational chemistry methods used to retrospectively analyse well known drugs for side effects. Using in silico and in vitro methods we have shown that both celecoxib and diclofenac but not naproxen exhibit off-target TRβ antagonist behaviour, which may be linked to their detrimental side effects.

Resistance to Thyroid Hormone Caused by a G344R Mutation of Thyroid Hormone Receptor Beta Gene: A Case Report Study

Background: Resistance to thyroid hormone (RTH), is a rare genetic disease. The aim of this research is to study a pediatric case of resistance to thyroid hormone (RTH) and its clinical manifestation. Methods: An infant demonstrating resistance to thyroid hormone (RTH) and her parents were subjected to THRB gene analysis by PCR amplification of peripheral blood DNA. The sequences were aligned and compared. Results: A heterozygous mutation, c.1030G>C, was found in exon 10 of THRB gene resulting in an amino acid substitution, G344R, in the encoded protein. Conclusion: In Chinese children, a heterozygous mutation of c.1030G>C in THRB gene may cause RTHS.

A novel mutation of the THRB gene in a Japanese family with resistance to thyroid hormone

Resistance to thyroid hormone (RTH; OMIM 190160) is an inherited syndrome of reduced sensitivity to thyroid hormone. RTH, in majority, is caused by monoallelic inactivating mutation of THRB, which encodes the thyroid hormone receptor β (TRβ) (1). RTH is endocrinologically characterized by high serum thyroid hormones together with inappropriately normal TSH. The severity of hormonal resistance varies among different tissues in an affected individual, due to differences in the relative expression of TRβ and thyroid hormone receptor alpha (TRα) in different tissues (2). To date, more than 100 THRB mutations have been reported among RTH patients. Most mutations are located in the ligand-binding domain of TR. They interfere with the function of the normal TR because of their dominant negative effect (1). We report a novel mutation of the THRB gene in a family with RTH.

Inexpensive Method for Selecting Receptor Structures for Virtual Screening.

This article introduces a screening performance index (SPI) to help select from a number of experimental structures one or a few that are more likely to identify more actives among its top hits from virtual screening of a compound library. It achieved this by docking only known actives to the experimental structures without considering a large number of decoys to reduce computational costs. The SPI is calculated by using the docking energies of the actives to all the receptor structures. We evaluated the performance of the SPI by applying it to study eight protein systems: fatty acid binding protein adipocyte FABP4, serine/threonine-protein kinase BRAF, beta-1 adrenergic receptor ADRB1, TGF-beta receptor type I TGFR1, adenosylhomocysteinase SAHH, thyroid hormone receptor beta-1 THB, phospholipase A2 group IIA PA2GA, and cytochrome P450 3a4 CP3A4. We found that the SPI agreed with the results from other popular performance metrics such as Boltzmann-Enhanced Discrimination Receiver Operator Characteristics (BEDROC), Robust Initial Enhancement (RIE), Area Under Accumulation Curve (AUAC), and Enrichment Factor (EF) but is less expensive to calculate. SPI also performed better than the best docking energy, the molecular volume of the bound ligand, and the resolution of crystal structure in selecting good receptor structures for virtual screening. The implications of these findings were further discussed in the context of ensemble docking, in situations when no experimental structure for the targeted protein was available, or under circumstances when quick choices of receptor structures need to be made before quantitative indexes such as the SPI and BEDROC can be calculated.