scholarly journals Differential Regulation Of Steroidogenic Enzyme Genes by TRα Signaling in Testicular Leydig Cells

2014 ◽  
Vol 28 (6) ◽  
pp. 822-833 ◽  
Author(s):  
Eunsook Park ◽  
Yeawon Kim ◽  
Hyun Joo Lee ◽  
Keesook Lee
Keyword(s):  
Thyroid Hormone ◽  
Leydig Cells ◽  
Promoter Activity ◽  
Molecular Mechanisms ◽  
Thyroid Hormone Receptor ◽  
Regulatory Protein ◽  
Differential Regulation ◽  
Gene Promoters ◽  
Steroidogenic Enzyme ◽  
Testicular Steroidogenesis

Abstract Thyroid hormone signaling has long been implicated in mammalian testicular function, affecting steroidogenesis in testicular Leydig cells. However, its molecular mechanism is not well understood. Here, we investigated the molecular action of thyroid hormone receptor-α (TRα) on mouse testicular steroidogenesis. TRα/thyroid hormone (T3) signaling differentially affected the expression of steroidogenic enzyme genes, mainly regulating their promoter activity. TRα directly regulated the promoter activity of the cytochrome P450 17α-hydroxylase/C17–20 lyase gene, elevating its expression in the presence of T3. TRα also indirectly regulated the expression of steroidogenic enzyme genes, such as steroidogenic acute regulatory protein and 3β-hydroxysteroid dehydrogenase, by modulating the transactivation of Nur77 on steroidogenic enzyme gene promoters through protein-protein interaction. TRα enhanced Nur77 transactivation by excluding histone deacetylases from Nur77 in the absence of T3, whereas liganded TRα inhibited Nur77 transactivation, likely due to interfering with the recruitment of coactivator such as the steroid receptor coactivator-1 to Nur77. Together, these findings suggest a role of TRα/T3 in testicular steroidogenesis and may provide molecular mechanisms for the differential regulation of steroidogenic enzyme genes by thyroid hormone.

scholarly journals Constitutive activation of gene expression by thyroid hormone receptor results from reversal of p53-mediated repression.

1997 ◽  
Vol 17 (12) ◽  
pp. 7195-7207 ◽  
Author(s):  
J S Qi ◽  
V Desai-Yajnik ◽  
Y Yuan ◽  
H H Samuels
Keyword(s):  
Gene Expression ◽  
Thyroid Hormone ◽  
Hormone Receptor ◽  
Promoter Activity ◽  
Hormone Receptors ◽  
Thyroid Hormone Receptor ◽  
Gene Promoters ◽  
Wild Type ◽  
Constitutive Activation

Thyroid hormone receptor (T3R) is a member of the steroid hormone receptor gene family of nuclear hormone receptors. In most cells T3R activates gene expression only in the presence of its ligand, L-triiodothyronine (T3). However, in certain cell types (e.g., GH4C1 cells) expression of T3R leads to hormone-independent constitutive activation. This activation by unliganded T3R occurs with a variety of gene promoters and appears to be independent of the binding of T3R to specific thyroid hormone response elements (TREs). Previous studies indicate that this constitutive activation results from the titration of an inhibitor of transcription. Since the tumor suppresser p53 is capable of repressing a wide variety of gene promoters, we considered the possibility that the inhibitor is p53. Evidence to support this comes from studies indicating that expression of p53 blocks T3R-mediated constitutive activation in GH4C1 cells. In contrast with hormone-independent activation by T3R, p53 had little or no effect on T3-dependent stimulation which requires TREs. In addition, p53 mutants which oligomerize with wild-type p53 and interfere with its function also increase promoter activity. This enhancement is of similar magnitude to but is not additive with the stimulation mediated by unliganded T3R, suggesting that they target the same factor. Since p53 mutants are known to target wild-type p53 in the cell, this suggests that T3R also interacts with p53 in vivo and that endogenous levels of p53 act to suppress promoter activity. Evidence supporting both functional and physical interactions of T3R and p53 in the cell is presented. The DNA binding domain (DBD) of T3R is important in mediating constitutive activation, and the receptor DBD appears to functionally interact with the N terminus of p53 in the cell. In vitro binding studies indicate that the T3R DBD is important for interaction of T3R with p53 and that this interaction is reduced by T3. These findings are consistent with the in vivo studies indicating that p53 blocks constitutive activation but not ligand-dependent stimulation. These studies provide insight into mechanisms by which unliganded nuclear hormone receptors can modulate gene expression and may provide an explanation for the mechanism of action of the v-erbA oncoprotein, a retroviral homolog of chicken T3R alpha.

scholarly journals The nuclear receptors NUR77 and SF1 play additive roles with c-JUN through distinct elements on the mouse Star promoter

2008 ◽  
Vol 42 (2) ◽  
pp. 119-129 ◽  
Author(s):  
Luc J Martin ◽  
Jacques J Tremblay
Keyword(s):  
Nuclear Receptors ◽  
Leydig Cells ◽  
Promoter Activity ◽  
Molecular Mechanisms ◽  
Regulatory Protein ◽  
Regulatory Elements ◽  
Camp Signaling Pathway ◽  
Steroidogenic Cells ◽  
Steroidogenic Acute Regulatory

The steroidogenic acute regulatory protein plays an essential role in steroid biosynthesis in steroidogenic cells. It is involved in the transport of cholesterol through the mitochondrial membrane where the first step of steroidogenesis occurs. Star gene expression in testicular Leydig cells is regulated by the pituitary LH through the cAMP signaling pathway. So far, several transcription factors have been implicated in the regulation of Star promoter activity in these cells. These include the nuclear receptors NUR77 and SF1, AP-1 family members (particularly c-JUN), GATA4, C/EBPβ, DLX5/6, and CREB. Some of these factors were also shown to act in a cooperative manner to further enhance Star promoter activity. Here, we report that NUR77 and c-JUN have additive effects on the Star promoter. These effects were abolished only when both elements, NUR77 at −95 bp and AP-1 at −78 bp, were mutated. Consistent with this, in vitro co-immunoprecipitation revealed that NUR77 and c-JUN interact and that this interaction is mediated through part of the ligand binding domain of NUR77. Furthermore, we found that SF1 could cooperate with c-JUN on the mouse Star promoter but this cooperation involved different regulatory elements. Collectively, our data not only provide new insights into the molecular mechanisms that control mouse Star transcription in Leydig cells but also reveal a novel mechanism for the regulation of NR4A1-dependent genes in tissues where NUR77 and c-JUN factors are co-expressed.

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 Ligand-dependent enhancement of human antithrombin gene expression by retinoid X receptor α and thyroid hormone receptor β

1996 ◽  
Vol 318 (1) ◽  
pp. 263-270 ◽  
Author(s):  
René W. L. M. NIESSEN ◽  
Farhad REZAEE ◽  
Pieter H. REITSMA ◽  
Marjolein PETERS ◽  
Jan J. M. de VIJLDER ◽  
...  
Keyword(s):  
Gene Expression ◽  
Thyroid Hormone ◽  
Hormone Receptor ◽  
Promoter Region ◽  
Promoter Activity ◽  
Thyroid Hormone Receptor ◽  
Retinoid X Receptor ◽  
Hepatoma Cell Line ◽  
Promoter Fragment ◽  
Thyroid Hormone Receptor Β

We studied potential modulators of antithrombin gene expression. A putative hormone response element (HRE) was identified by sequence similarity analysis of the antithrombin promoter, situated between nucleotides -92 and -54 relative to the transcription start site. This HRE contains three hexanucleotide motifs with an AGGTCA consensus, which are potential targets of members of the steroid/thyroid superfamily of nuclear receptors. Stimulation of the hepatoma cell line HepG2 with the receptor ligands l-3,5,3´-tri-iodothyronine, all-trans retinoic acid, or their combination, increased production of antithrombin into the culture medium by 1.3-, 1.6-, and 2.0-fold, respectively. In contrast, the receptor ligand 1,25-dihydroxycholecalciferol [1,25-(OH)2VitD3] did not influence antithrombin production. Analysis of promoter chloramphenicol acetyltransferase (CAT) constructs, showed that the first 86 bp of the antithrombin promoter region are sufficient for basal transcription. The DNA length polymorphism of 32 bp or 108 bp, located upstream of position -276, did not influence antithrombin promoter activity. The antithrombin promoter activity dropped to background values when deleting the region -97/-49 of promoter fragment -453/+57. Transactivation of the antithrombin promoter by retinoid X receptor α (RXRα) (5–7-fold) or thyroid hormone receptor β (TRβ) (4–5-fold) was only observed when at least -167/+57 bp of the promoter region is present in CAT constructs, and when the appropriate ligand of the nuclear receptor was added. This transactivation was not observed upon deletion of the antithrombin promoter region -97/-49. With three copies of the antithrombin promoter fragment -109/-42 in front of the thymidine kinase minimal promoter, transactivation was only obtained with RXRα, and not with TRβ. In conclusion, these results indicate that the ligand-dependent enhancement of antithrombin gene expression is regulated by RXRα as well as by TRβ. Transactivation of antithrombin gene expression by RXRα and TRβ appears to be dependent upon the presence of promoter region up to nucleotide -167. The HRE segment (-109/-42) only confers RXRα responsiveness to a heterologous promoter. Further study is needed to unravel the exact nature of this HRE and its 5´-flanking sequences.

scholarly journals Six1 promotes skeletal muscle thyroid hormone response through regulation of the MCT10 transporter

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
John Girgis ◽  
Dabo Yang ◽  
Imane Chakroun ◽  
Yubing Liu ◽  
Alexandre Blais
Keyword(s):  
Gene Expression ◽  
Skeletal Muscle ◽  
Thyroid Hormone ◽  
Tibialis Anterior ◽  
Molecular Mechanisms ◽  
Thyroid Hormone Receptor ◽  
Muscle Metabolism ◽  
Loss Of Function ◽  
Fast Twitch Muscle ◽  
Fast Twitch

Abstract Background The Six1 transcription factor is implicated in controlling the development of several tissue types, notably skeletal muscle. Six1 also contributes to muscle metabolism and its activity is associated with the fast-twitch, glycolytic phenotype. Six1 regulates the expression of certain genes of the fast muscle program by directly stimulating their transcription or indirectly acting through a long non-coding RNA. We hypothesized that additional mechanisms of action of Six1 might be at play. Methods A combined analysis of gene expression profiling and genome-wide location analysis data was performed. Results were validated using in vivo RNA interference loss-of-function assays followed by measurement of gene expression by RT-PCR and transcriptional reporter assays. Results The Slc16a10 gene, encoding the thyroid hormone transmembrane transporter MCT10, was identified as a gene with a transcriptional enhancer directly bound by Six1 and requiring Six1 activity for full expression in adult mouse tibialis anterior, a predominantly fast-twitch muscle. Of the various thyroid hormone transporters, MCT10 mRNA was found to be the most abundant in skeletal muscle, and to have a stronger expression in fast-twitch compared to slow-twitch muscle groups. Loss-of-function of MCT10 in the tibialis anterior recapitulated the effect of Six1 on the expression of fast-twitch muscle genes and led to lower activity of a thyroid hormone receptor-dependent reporter gene. Conclusions These results shed light on the molecular mechanisms controlling the tissue expression profile of MCT10 and identify modulation of the thyroid hormone signaling pathway as an additional mechanism by which Six1 influences skeletal muscle metabolism.

Differential regulation of steroidogenic enzymes metabolizing testosterone or dihydrotestosterone by human chorionic gonadotropin in cultured rat neonatal interstitial cells

1990 ◽  
Vol 122 (2) ◽  
pp. 289-295 ◽  
Author(s):  
Eisuke P. Murono
Keyword(s):  
Chorionic Gonadotropin ◽  
Human Chorionic Gonadotropin ◽  
Leydig Cells ◽  
Reductase Activity ◽  
Hydroxysteroid Dehydrogenase ◽  
Interstitial Cells ◽  
Differential Regulation ◽  
Steroidogenic Enzyme ◽  
Isomerase Activity ◽  
Adult Leydig Cells

Abstract The present studies examined the effects of hCG on steroidogenic enzyme activities involved in the metabolism of testosterone or dihydroststosterone in cultured rat neonatal interstitial cells. 5α-reductase and 17β-hydroxysteroid dehydrogenase activities, which are involved in the conversion of testosterone to dihydrotestosterone and androstenedione, respectively, were low in cultured neonatal interstitial cells, were unresponsive to hCG and declined to undetectable levels during 14 days of culture. However, Δ5-3β-hydroxysteroid dehydrogenase-isomerase activity, which is involved in the biosynthesis of testosterone, and 5α-androstane-3α-hydroxysteroid dehydrogenase and 5α-androstane-3β-hydroxysteroid dehydrogenase activities, which are involved in the conversion of dihydrotestosterone to 5α-androstan-3α, 17β-diol and 5α-androstan-3β, 17β-diol, respectively, were maintained or increased by hCG during the same culture period. These results demonstrate that 5α-reductase and 17β-hydroxysteroid dehydrogenase activities do not play a significant role in regulating testosterone accumulation in fetal/neonatal Leydig cells, and they suggest that these cells are adapted to maintain high testosterone but low dihydrotestosterone levels. The present results demonstrate also that fetal/neonatal Leydig cells differ from immature or adult Leydig cells with respect to the sensitivity of 5α-reductase activity to LH/hCG.

Sign in / Sign up

Export Citation Format

Share Document