scholarly journals Desethylamiodarone antagonizes the effect of thyroid hormone at the molecular level

2001 ◽  
pp. 59-64 ◽  
Author(s):  
F Bogazzi ◽  
L Bartalena ◽  
S Brogioni ◽  
A Burelli ◽  
F Raggi ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Molecular Mechanisms ◽  
Thyroid Hormone Receptor ◽  
Molecular Level ◽  
Inhibitory Effect ◽  
Mobility Shift ◽  
Down Regulation ◽  
Nih3t3 Cells ◽  
Peripheral Tissues

OBJECTIVE: To evaluate the molecular mechanisms of the inhibitory effects of amiodarone and its active metabolite, desethylamiodarone (DEA) on thyroid hormone action. MATERIALS AND METHODS: The reporter construct ME-TRE-TK-CAT or TSHbeta-TRE-TK-CAT, containing the nucleotide sequence of the thyroid hormone response element (TRE) of either malic enzyme (ME) or TSHbeta genes, thymidine kinase (TK) and chloramphenicol acetyltransferase (CAT) was transiently transfected with RSV-TRbeta into NIH3T3 cells. Gel mobility shift assay (EMSA) was performed using labelled synthetic oligonucleotides containing the ME-TRE and in vitro translated thyroid hormone receptor (TR)beta. RESULTS: Addition of 1 micromol/l T4 or T3 to the culture medium increased the basal level of ME-TRE-TK-CAT by 4.5- and 12.5-fold respectively. Amiodarone or DEA (1 micromol/l) increased CAT activity by 1.4- and 3.4-fold respectively. Combination of DEA with T4 or T3 increased CAT activity by 9.4- and 18.9-fold respectively. These data suggested that DEA, but not amiodarone, had a synergistic effect with thyroid hormone on ME-TRE, rather than the postulated inhibitory action; we supposed that this was due to overexpression of the transfected TR into the cells. When the amount of RSV-TRbeta was reduced until it was present in a limited amount, allowing competition between thyroid hormone and the drug, addition of 1 micromol/l DEA decreased the T3-dependent expression of the reporter gene by 50%. The inhibitory effect of DEA was partially due to a reduced binding of TR to ME-TRE, as assessed by EMSA. DEA activated the TR-dependent down-regulation by the negative TSH-TRE, although at low level (35% of the down-regulation produced by T3), whereas amiodarone was ineffective. Addition of 1 micromol/l DEA to T3-containing medium reduced the T3-TR-mediated down-regulation of TSH-TRE to 55%. CONCLUSIONS: Our results demonstrate that DEA, but not amiodarone, exerts a direct, although weak, effect on genes that are regulated by thyroid hormone. High concentrations of DEA antagonize the action of T3 at the molecular level, interacting with TR and reducing its binding to TREs. This effect may contribute to the hypothyroid-like effect observed in peripheral tissues of patients receiving amiodarone treatment.

scholarly journals Dronerarone Acts as a Selective Inhibitor of 3,5,3′-Triiodothyronine Binding to Thyroid Hormone Receptor-α1: In Vitro and in Vivo Evidence

Endocrinology ◽  
2003 ◽  
Vol 144 (2) ◽  
pp. 552-558 ◽  
Author(s):  
H. C. van Beeren ◽  
W. M. C. Jong ◽  
E. Kaptein ◽  
T. J. Visser ◽  
O. Bakker ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Hormone Receptor ◽  
Thyroid Hormone Receptor ◽  
Density Lipoprotein ◽  
Inhibitory Effect ◽  
Selective Inhibitor ◽  
Receptor Protein ◽  
Qtc Interval

Dronedarone (Dron), without iodine, was developed as an alternative to the iodine-containing antiarrhythmic drug amiodarone (AM). AM acts, via its major metabolite desethylamiodarone, in vitro and in vivo as a thyroid hormone receptor α1 (TRα1) and TRβ1 antagonist. Here we investigate whether Dron and/or its metabolite debutyldronedarone inhibit T3 binding to TRα1 and TRβ1in vitro and whether dronedarone behaves similarly to amiodarone in vivo. In vitro , Dron had a inhibitory effect of 14% on the binding of T3 to TRα1, but not on TRβ1. Desethylamiodarone inhibited T3 binding to TRα1 and TRβ1 equally. Debutyldronedarone inhibited T3 binding to TRα1 by 77%, but to TRβ1 by only 25%. In vivo , AM increased plasma TSH and rT3, and decreased T3. Dron decreased T4 and T3, rT3 did not change, and TSH fell slightly. Plasma total cholesterol was increased by AM, but remained unchanged in Dron-treated animals. TRβ1-dependent liver low density lipoprotein receptor protein and type 1 deiodinase activities decreased in AM-treated, but not in Dron-treated, animals. TRα1-mediated lengthening of the QTc interval was present in both AM- and Dron-treated animals. The in vitro and in vivo findings suggest that dronedarone via its metabolite debutyldronedarone acts as a TRα1-selective inhibitor.

scholarly journals Antithyroid Drugs Inhibit Thyroid Hormone Receptor-Mediated Transcription

2007 ◽  
Vol 92 (3) ◽  
pp. 1066-1072 ◽  
Author(s):  
Kenji Moriyama ◽  
Tetsuya Tagami ◽  
Takeshi Usui ◽  
Mitsuhide Naruse ◽  
Takuo Nambu ◽  
...  
Keyword(s):  
Gene Expression ◽  
Thyroid Hormone ◽  
Hormone Receptors ◽  
Thyroid Hormone Receptor ◽  
Transient Gene Expression ◽  
Antithyroid Drugs ◽  
Transcriptional Level ◽  
Dependent Manner ◽  
Peripheral Tissues

Abstract Context: Methimazole (MMI) and propylthiouracil (PTU) are widely used as antithyroid drugs (ATDs) for the treatment of Graves’ disease. Both MMI and PTU reduce thyroid hormone levels by several mechanisms, including inhibition of thyroid hormone synthesis and secretion. In addition, PTU decreases 5′-deiodination of T4 in peripheral tissues. ATDs may also interfere with T3 binding to nuclear thyroid hormone receptors (TRs). However, the effect of ATDs on the transcriptional activities of T3 mediated by TRs has not been studied. Objective: The present study was undertaken to determine whether ATDs have an effect on the gene transcription regulated by T3 and TRs in vitro. Methods: Transient gene expression experiments and GH secretion assays were performed. To elucidate possible mechanisms of the antagonistic action of ATDs, the interaction between TR and nuclear cofactors was examined. Results: In the transient gene expression experiments, both MMI and PTU significantly suppressed transcriptional activities mediated by the TR and T3 in a dose-dependent manner. In mammalian two-hybrid assays, both drugs recruited one of the nuclear corepressors, nuclear receptor corepressor, to the TR in the absence of T3. In addition, PTU dissociated nuclear coactivators, such as steroid receptor coactivator-1 and glucocorticoid receptor interacting protein-1, from the TR in the presence of T3. Finally, MMI decreased the GH release that was stimulated by T3. Conclusions: ATDs inhibit T3 action by recruitment of transcriptional corepressors and/or dissociation of coactivators. This is the first report to show that ATDs can modulate T3 action at the transcriptional level.

Thyroid hormones regulate phosphate homoeostasis through transcriptional control of the renal type IIa sodium-dependent phosphate co-transporter (Npt2a) gene

2010 ◽  
Vol 427 (1) ◽  
pp. 161-169 ◽  
Author(s):  
Mariko Ishiguro ◽  
Hironori Yamamoto ◽  
Masashi Masuda ◽  
Mina Kozai ◽  
Yuichiro Takei ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Hormones ◽  
Molecular Mechanisms ◽  
Hormone Receptors ◽  
Critical Role ◽  
Serum Phosphate ◽  
Luciferase Assay ◽  
Mobility Shift ◽  
Intron 1 ◽  
Sodium Dependent

The type IIa renal sodium-dependent phosphate (Na/Pi) co-transporter Npt2a is implicated in the control of serum phosphate levels. It has been demonstrated previously that renal Npt2a protein and its mRNA expression are both up-regulated by the thyroid hormone T3 (3,3′,5-tri-iodothyronine) in rats. However, it has never been established whether the induction was mediated by a direct effect of thyroid hormones on the Npt2a promoter. To address the role of Npt2a in T3-dependent regulation of phosphate homoeostasis and to identify the molecular mechanisms by which thyroid hormones modulate Npt2a gene expression, mice were rendered pharmacologically hypo- and hyper-thyroid. Hypothyroid mice showed low levels of serum phosphate and a marked decrease in renal Npt2a protein abundance. Importantly, we also showed that Npt2a-deficient mice had impaired serum phosphate responsiveness to T3 compared with wild-type mice. Promoter analysis with a luciferase assay revealed that the transcriptional activity of a reporter gene containing the Npt2a promoter and intron 1 was dependent upon TRs (thyroid hormone receptors) and specifically increased by T3 in renal cells. Deletion analysis and EMSAs (electrophoretic mobility-shift assays) determined that there were unique TREs (thyroid-hormone-responsive elements) within intron 1 of the Npt2a gene. These results suggest that Npt2a plays a critical role as a T3-target gene, to control phosphate homoeostasis, and that T3 transcriptionally activates the Npt2a gene via TRs in a renal cell-specific manner.

Age-associated features of the expression level of apoptosis markers in cardiomyocytes of patients with dilated cardiomyopathy

2022 ◽  
pp. 885-890
Author(s):  
К.П. Кравченко ◽  
К. Л. Козлов ◽  
А.О. Дробинцева ◽  
Д.С. Медведев ◽  
В.О. Полякова
Keyword(s):  
Cell Death ◽  
Dilated Cardiomyopathy ◽  
Molecular Mechanisms ◽  
Molecular Level ◽  
Confocal Laser ◽  
Control Group ◽  
Cellular Mechanisms ◽  
Apoptosis Pathway ◽  
Bax Protein

Для понимания патогенеза дилатационной кардиомиопатии (ДКМП) необходимо установить молекулярно-клеточные механизмы старения миокарда, в том числе связанные с программируемой клеточной гибелью, молекулярные механизмы которого практически не изучены. Цель работы - изучение маркеров апоптоза в кардиомиоцитах у пациентов с ДКМП in vitro. В работе использовали метод первичных диссоциированных клеточных культур и метод иммунофлюоресцентной конфокальной лазерной микроскопии. Для моделирования клеточного старения использовали клетки 3-го и 14-го пассажей, соответствующие «молодым» и «старым» культурам. На молекулярном уровне старение клеток кардиомиоцитов сопровождалось повышением экспрессии р16 в 2 раза по сравнению с «молодыми культурами» как в контрольной, так и в группе с ДКМП. Также установлено, что экспрессия р16 в культурах, взятых от пациентов с патологией, была в 2 раза выше, чем в аналогичных культурах от здоровых пациентов. Экспрессия р21 была повышена в группе с ДКМП по сравнению с контрольной группой, однако при старении культуры экспрессия p21 не изменялась, оставаясь на высоком уровне. Наиболее значимые различия были получены при сравнении экспрессии Bax в культуре клеток кардиомиоцитов из группы с ДКМП в «молодой» культуре с нормой - в 3,2 раза. Старение клеток миокарда на молекулярном уровне проявлялось в повышении экспрессии белка Baх, именно он является запускающим механизмом митохондриального пути апоптоза. Возможно, этот путь клеточной гибели является превалирующем при ДКМП. To understand the pathogenesis of dilated cardiomyopathy (DCMP), it is necessary to establish the molecular-cellular mechanisms of myocardial aging, including those associated with programmed cell death, the molecular mechanisms of which have not been practically studied. The aim of this work is to study markers of apoptosis in cardiomyocytes of patients with DCMP in vitro. We used the method of primary dissociated cell cultures and the method of immunofluorescence confocal laser microscopy. Cells of the 3 and 14 passages, corresponding to «young» and «old» cultures, were used to simulate cellular senescence. Results. At the molecular level, aging of cardiomyocyte cells was accompanied by a twofold increase in the expression of p16 compared to «young cultures» both in the control group and in the group with DCMP. It was also found that the expression of p16 in cultures taken from patients with pathology was 2 times higher than in similar cultures from healthy patients. The expression of p21 was increased in the group with DCMP compared to the control; however, with aging of the culture, the expression of p21 did not change, remaining at a significant level. The most significant differences were obtained when comparing the expression of Bax in the cell culture of cardiomyocytes from the group with DCMP in a «young» culture compared with the norm, 3,2 times. Aging of myocardial cells at the molecular level was manifested in an increase in the expression of the Bax protein, which is the triggering mechanism of the mitochondrial apoptosis pathway. It is possible that this pathway of cell death is prevalent in DCMP.

scholarly journals Tetracycline Analogs Inhibit Osteoclast Differentiation by Suppressing MMP-9-Mediated Histone H3 Cleavage

2019 ◽  
Vol 20 (16) ◽  
pp. 4038 ◽  
Author(s):  
Yeojin Kim ◽  
Jinman Kim ◽  
Hyerim Lee ◽  
Woo-Ri Shin ◽  
Sheunghun Lee ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Osteoclast Differentiation ◽  
Histone H3 ◽  
Inhibitory Effect ◽  
Osteoclast Formation ◽  
Receptor Activator ◽  
New Strategy ◽  
Docking Approach ◽  
Metalloproteinase 9

Osteoporosis is a common disorder of bone remodeling, caused by the imbalance between bone resorption by osteoclasts and bone formation by osteoblasts. Recently, we reported that matrix metalloproteinase-9 (MMP-9)-dependent histone H3 proteolysis is a key event for proficient osteoclast formation. Although it has been reported that several MMP-9 inhibitors, such as tetracycline and its derivatives, show an inhibitory effect on osteoclastogenesis, the molecular mechanisms for this are not fully understood. Here we show that tetracycline analogs, especially tigecycline and minocycline, inhibit osteoclast formation by blocking MMP-9-mediated histone H3 tail cleavage. Our molecular docking approach found that tigecycline and minocycline are the most potent inhibitors of MMP-9. We also observed that both inhibitors significantly inhibited H3 tail cleavage by MMP-9 in vitro. These compounds inhibited receptor activator of nuclear factor kappaB ligand (RANKL)-induced osteoclast formation by blocking the NFATc1 signaling pathway. Furthermore, MMP-9-mediated H3 tail cleavage during osteoclast differentiation was selectively blocked by these compounds. Treatment with both tigecycline and minocycline rescued the osteoporotic phenotype induced by prednisolone in a zebrafish osteoporosis model. Our findings demonstrate that the tetracycline analogs suppress osteoclastogenesis via MMP-9-mediated H3 tail cleavage, and suggest that MMP-9 inhibition could offer a new strategy for the treatment of glucocorticoid-induced osteoporosis.

scholarly journals Mutations in thyroid hormone receptor α1 cause premature neurogenesis and progenitor cell depletion in human cortical development

2019 ◽  
Vol 116 (45) ◽  
pp. 22754-22763 ◽  
Author(s):  
Teresa G. Krieger ◽  
Carla M. Moran ◽  
Alberto Frangini ◽  
W. Edward Visser ◽  
Erik Schoenmakers ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Progenitor Cells ◽  
Hormone Receptor ◽  
Progenitor Cell ◽  
Thyroid Hormone Receptor ◽  
Cortical Development ◽  
Neural Progenitor Cell ◽  
Cortical Layer ◽  
Lineage Tracing

Mutations in the thyroid hormone receptor α 1 gene (THRA) have recently been identified as a cause of intellectual deficit in humans. Patients present with structural abnormalities including microencephaly, reduced cerebellar volume and decreased axonal density. Here, we show that directed differentiation of THRA mutant patient-derived induced pluripotent stem cells to forebrain neural progenitors is markedly reduced, but mutant progenitor cells can generate deep and upper cortical layer neurons and form functional neuronal networks. Quantitative lineage tracing shows that THRA mutation-containing progenitor cells exit the cell cycle prematurely, resulting in reduced clonal output. Using a micropatterned chip assay, we find that spatial self-organization of mutation-containing progenitor cells in vitro is impaired, consistent with down-regulated expression of cell–cell adhesion genes. These results reveal that thyroid hormone receptor α1 is required for normal neural progenitor cell proliferation in human cerebral cortical development. They also exemplify quantitative approaches for studying neurodevelopmental disorders using patient-derived cells in vitro.

scholarly journals The molecular mechanisms of inhibitory effect of androstenone on hepatic skatole metabolism in relation to boar taint

2005 ◽  
Vol 2005 ◽  
pp. 36-36
Author(s):  
E. Doran ◽  
J. D. McGivan ◽  
M.F. Whittington ◽  
J. D. Wood
Keyword(s):  
Molecular Mechanisms ◽  
Inhibitory Effect ◽  
Boar Taint ◽  
Cyp2e1 Expression ◽  
Low Activity ◽  
Low Expression ◽  
Excessive Accumulation ◽  
Expression And Activity

Boar taint is off-odours in cooked pork from uncastrated male pigs. It is caused by an excessive accumulation of skatole and androstenone in backfat. Accumulation of skatole is due to a low expression and activity of hepatic enzyme CYP2E1. The mechanism of androstenone accumulation is not clear. It could be due to low activity and expression of 3ß-hydroxysteroid dehydrogenase (HSD), an enzyme metabolising androstenone in liver. On the basis of our previous in vivo experiments with castrated animals we suggest that accumulation of skatole is regulated by androstenone. Castrated pigs manifest lower levels of skatole and androstenone and higher CYP2E1 expression. We hypothesise that high levels of androstenone inhibits CYP2E1 expression and hence, reduces the rate of hepatic skatole metabolism. The aims of the present study were (i) to investigate the expression of androstenone-metabolising enzyme HSD in liver of pigs with high and low skatole and androstenone deposition; (ii) to investigate the effect of androstenone on expression of the skatole-metabolising enzyme CYP2E1 in vitro (in cell culture).

Fatty Acyl-CoAs Are Potent Inhibitors of the Nuclear Thyroid Hormone Receptor In Vitro

1990 ◽  
Vol 107 (5) ◽  
pp. 699-702 ◽  
Author(s):  
Qiulin Li ◽  
Naoki Yamamoto ◽  
Akira Inoue ◽  
Seiji Morisawa
Keyword(s):  
Thyroid Hormone ◽  
Hormone Receptor ◽  
Thyroid Hormone Receptor ◽  
Fatty Acyl

scholarly journals MeCP2 Promotes Colorectal Cancer Metastasis by Modulating ZEB1 Transcription

Cancers ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 758
Author(s):  
Dan Luo ◽  
Wei Ge
Keyword(s):  
Colorectal Cancer ◽  
Molecular Mechanisms ◽  
Cancer Metastasis ◽  
The Cancer Genome Atlas ◽  
Mobility Shift ◽  
Migration Ability ◽  
Invasion And Migration ◽  
Distant Organ Metastasis

Background: Recurrence and distant organ metastasis is a major cause of death in colorectal cancer (CRC); however, the underlying molecular mechanisms regulating this phenomenon are poorly understood. MeCP2 is a key epigenetic regulator and is amplified in many types of cancer. Its role in CRC and the molecular mechanisms underlying its action remain unknown. Methods: We used western blot and immunohistochemistry to detect MeCP2 expression in CRC tissues, and then investigated its biological functions in vitro and in vivo. Chromatin immunoprecipitation, co-immunoprecipitation, and electrophoretic mobility shift assays were used to detect the associations among MeCP2 (Methyl-CpG binding protein 2), SPI1 (Spi-1 Proto-Oncogene), and ZEB1 (Zinc Finger E-Box Binding Homeobox 1). Results: Using the Cancer Genome Atlas and Oncomine databases, we found MeCP2 expression was upregulated in CRC tissues and this upregulation was related to poor prognosis. Meanwhile, MeCP2 depletion (KO/KD) in CRC cells significantly inhibited stem cell frequency, and invasion and migration ability in vitro, and suppressed CRC metastasis in vivo. Mechanistically, we show MeCP2 binds to the transcription factor SPI1, and aids its recruitment to the ZEB1 promoter. SPI1 then facilitates ZEB1 expression at the transcription level. In turn, ZEB1 induces the expression of MMP14, CD133, and SOX2, thereby maintaining CRC stemness and metastasis. Conclusions: MeCP2 is a novel regulator of CRC metastasis. MeCP2 suppression may be a promising therapeutic strategy in CRC.

Sign in / Sign up

Export Citation Format

Share Document