NCoR1 and SMRT play unique roles in thyroid hormone signaling in the liver
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE54192 | GEO | 2014/11/21
SECONDARY ACCESSION(S): PRJNA235393
REPOSITORIES: GEO
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Project description:NCoR1 (Nuclear receptor Co-Repressor) and SMRT (Silencing Mediator of Retinoid and Thyroid hormone receptor) are well-recognized coregulators of nuclear receptor (NR) action. However, their unique roles in the regulation of thyroid hormone (TH) signaling in specific cell types have not been determined. To accomplish this we generated a mouse model that lacked function of either NCoR1 or SMRT or both in the liver only. Despite both corepressors being present in the liver, SMRT had no ability to regulate TH signaling when deleted in either euthyroid or hypothyroid animals. In contrast, disruption of NCoR1 action confirmed that it is the principal mediator of TH sensitivity in vivo. While SMRT played little role in TH signaling alone, when disrupted in combination with NCoR1 it greatly accentuated the activation of hepatic lipogenesis regulated by NCoR1. Thus, corepressor specificity exists in vivo and NCoR1 is the principal regulator of TH action in the liver. However, both NCoR1 and SMRT collaborate to control hepatic lipogenesis and lipid storage, which likely reflects their cooperative activity in regulating the action of multiple NRs including the thyroid hormone receptor (TR). RNA was extracted from livers from 3 individual mice for each group (Double-floxed, Liver specific-SMRT knock out, and Liver specific-double knock out); all were euthyroid, female mice
2014-11-21 | E-GEOD-54192 | biostudies-arrayexpress
Project description:Objective: Nuclear receptor action is mediated in part by the nuclear receptor corepressor 1 (NCOR1) and the silencing mediator of retinoic acid and thyroid hormone receptor (SMRT; also known as NCOR2). NCOR1 and SMRT regulate metabolic pathways that govern body mass, insulin sensitivity and energy expenditure and represent an understudied area in the realm of metabolic health and disease. Previously, we found that NCOR1 and SMRT are essential for maintaining metabolic homeostasis and their knockout (KO) leads to rapid weight loss and hypoglycemia, which is not survivable. Because of a potential defect in glucose absorption, we sought to determine the role of NCOR1 and SMRT specifically in intestinal epithelial cells (IECs). Methods: We used a post-natal strategy to disrupt NCOR1 and SMRT throughout IECs in adult mice. These mice were characterized metabolically by assessing body weight, glucose levels and subjecting the mice to metabolic phenotyping, body composition analysis and glucose tolerance testing. IECs were isolated from the jejunum of the small intestine and profiled by bulk RNA sequencing. Results: We found that the post-natal KO of NCOR1 and SMRT from IECs leads to rapid weight loss and hypoglycemia with a significant reduction in survival. This was accompanied by alterations in glucose metabolism and activation of fatty acid oxidation in IECs. Metabolic phenotyping confirmed a reduction in body mass driven by a loss of body fat without any difference in food intake. This appeared to be driven by a reduction of key intestinal carbohydrate transporters, including SGLT1, GLUT2 and GLUT5. Conclusions: Intestinal NCOR1 and SMRT act in tandem to regulate glucose levels and body weight. This in part may be mediated by regulation of intestinal carbohydrate transporters.
2024-08-12 | GSE268594 | GEO
Project description:This SuperSeries is composed of the following subset Series: GSE16017: Thyroid Hormone (TH) Controls The Remodeling Of The Pancreas And The Liver, Part B GSE16018: Thyroid Hormone (TH) Controls The Remodeling Of The Pancreas And The Liver, Part C GSE16074: Thyroid Hormone (TH) Controls The Remodeling Of The Pancreas And The Liver, Part A Refer to individual Series
2010-05-16 | E-GEOD-16075 | biostudies-arrayexpress
Project description:Thyroid hormones (THs) are critical regulators of systemic energy metabolism and homeostasis. In the liver, high TH action protects against steatosis by enhancing cholesterol and triglyceride turnover, with thyroid hormone receptor beta (THRB) signaling playing a pivotal role. This study probed the potential interaction between THRB action and another critical regulator of liver energy metabolism, the circadian clock. Liver transcriptome analysis of THRB deficient (THRBKO) mice under normal chow conditions revealed a markedly modest impact of THRB deletion. Temporal transcriptome and lipidome profiling uncovered significant alterations in diurnal metabolic rhythms attributable to THRB deficiency pointing to a pro-steatotic state with elevated levels of cholesterol, tri- and diacylglycerides, and fatty acids. These findings were confirmed by THRB agonization in hepatocytes under steatosis-promoting conditions in vitro. Integration of transcriptome profiles from THRBKO mice and mice with induced high or low TH action identified a subset of TH responsive but THRB insensitive genes implicated in immune processes. In summary, our study reveals a complex time-of-day dependent interaction of different TH-related signals in the regulation of liver physiology indicating an opportunity for chronopharmacological approaches to TH/THR(B) manipulation in fatty liver diseases.
2024-08-13 | GSE254467 | GEO
Project description:NCoR1 and SMRT play unique roles in thyroid hormone signaling in the liver
| PRJNA235393 | ENA
Project description:Thyroid hormones (TH) are powerful regulators of metabolism with major effects on body weight, cholesterol, and liver fat that have been exploited pharmacologically for many years. Activation of gene expression by TH action is canonically ascribed to a hormone- dependent “switch” from corepressor to activator binding to thyroid hormone receptors (TR), while the mechanism of TH-dependent repression is controversial. To address this, we generated a mouse line in which endogenous TRβ1 was epitope-tagged to allow precise chromatin immunoprecipitation at the low physiological levels of TR, and defined high confidence binding sites where TR functioned at enhancers regulated in the same direction as the nearest gene in a TRβ-dependent manner. Remarkably, although positive and negative regulation by TH have been ascribed to different mechanisms, TR binding was highly enriched at canonical DR4 motifs irrespective of the transcriptional direction of the enhancer. The canonical NCoR1/HDAC3 corepressor complex was reduced but not completely dismissed by TH and, surprisingly, similar effects were seen at enhancers associated with negatively as well as positively regulated genes. Conversely, coactivator CBP was found at all TH-regulated enhancers, with transcriptional activity correlating with the ratio of CBP to NCoR rather than their presence or absence. These results demonstrate that, in contrast to the canonical “all or none” coregulator switch model, TH regulates gene expression by orchestrating a shift in the relative binding of corepressors and coactivators.
2021-01-01 | GSE159648 | GEO
Project description:The thyroid hormone receptor (TR) has been proposed to regulate target genes in the absence of triiodothyronine (T3), through the recruitment of the corepressors, NCoR and SMRT. NCoR and SMRT may thus play a key role in both hypothyroidism and resistance to thyroid hormone, though this has never been tested in vivo. To accomplish this we developed mice that express in the liver a NCoR protein (L-NCoR∆ID) that cannot interact with the TR. L-NCoR∆ID mice develop normally, however when made hypothyroid the repression of many positively regulated T3-target genes is abrogated, demonstrating that NCoR plays a specific and sufficient role in repression by the unliganded TR. Remarkably, in the euthyroid state, expression of many T3-targets are also upregulated in L-NCoR∆ID mice, demonstrating that NCoR also determines the magnitude of the response to T3 in euthyroid animals. While positive T3 targets were upregulated in L-NCoR∆ID mice in the hypo and euthyroid state there was less effect seen on negatively regulated T3 target genes. Thus, NCoR is a specific regulator of T3-action in vivo and mediates the activity of the unliganded TR. Furthermore, NCoR may play a key role in determining the differences in individual responses to similar levels of circulating T3. Keywords: NCoR, thyroid hormone signaling, mouse liver, DNA Microarray To better assess the role of NCoR in positive and negative regulation we performed micorarray analysis of gene expression in the livers of euthyroid and hypothyroid control and L-NCoR∆ID mice.
2008-12-03 | E-GEOD-10001 | biostudies-arrayexpress
Project description:Corepressors negatively regulate gene expression by chromatin compaction. Targeted regulation of gene expression could provide a means to control endothelial cell phenotype. We hypothesize that by targeting corepressor proteins, endothelial angiogenic function can be improved. To study this, the expression and function of nuclear corepressors in human umbilical vein endothelial cells (HUVEC) and in murine organ culture was studied. RNA-seq revealed that nuclear receptor corepressor 1 (NCoR1), Silencing Mediator of Retinoid and Thyroid hormone receptors (SMRT) and repressor element-1 silencing transcription factor (REST) are the highest expressed corepressors in HUVECs. Knockout and knockdown strategies demonstrated that the depletion of NCoR1 increased the angiogenic capacity of endothelial cells, whereas depletion of SMRT or REST did not. Interestingly, the effect was VEGF signaling independent. NCoR1 depletion significantly upregulated angiogenesis-associated genes, especially tip cell genes, including ESM1, DLL4 and NOTCH4, as observed by RNA- and ATAC-seq. Confrontation assays comparing cells with and without NCoR1-deficiency revealed that loss of NCoR1 promotes a tip-cell position during spheroid sprouting. Moreover, a proximity ligation assay identified NCoR1 as a direct binding partner of the Notch-signaling-related transcription factor RBPJk. Luciferase assays showed that siRNA-mediated knockdown of NCoR1 promotes RBPJk activity. Furthermore, NCoR1 downregulation prompts upregulation of several elements in the Notch signaling cascade. Downregulation of NOTCH4, but not NOTCH1, prevented the positive effect of NCoR1 knockdown on spheroid outgrowth. Collectively, these data indicate that decreasing NCOR1 expression is an attractive approach to promote angiogenic function.
2024-02-12 | GSE242671 | GEO
Project description:Corepressors negatively regulate gene expression by chromatin compaction. Targeted regulation of gene expression could provide a means to control endothelial cell phenotype. We hypothesize that by targeting corepressor proteins, endothelial angiogenic function can be improved. To study this, the expression and function of nuclear corepressors in human umbilical vein endothelial cells (HUVEC) and in murine organ culture was studied. RNA-seq revealed that nuclear receptor corepressor 1 (NCoR1), Silencing Mediator of Retinoid and Thyroid hormone receptors (SMRT) and repressor element-1 silencing transcription factor (REST) are the highest expressed corepressors in HUVECs. Knockout and knockdown strategies demonstrated that the depletion of NCoR1 increased the angiogenic capacity of endothelial cells, whereas depletion of SMRT or REST did not. Interestingly, the effect was VEGF signaling independent. NCoR1 depletion significantly upregulated angiogenesis-associated genes, especially tip cell genes, including ESM1, DLL4 and NOTCH4, as observed by RNA- and ATAC-seq. Confrontation assays comparing cells with and without NCoR1-deficiency revealed that loss of NCoR1 promotes a tip-cell position during spheroid sprouting. Moreover, a proximity ligation assay identified NCoR1 as a direct binding partner of the Notch-signaling-related transcription factor RBPJk. Luciferase assays showed that siRNA-mediated knockdown of NCoR1 promotes RBPJk activity. Furthermore, NCoR1 downregulation prompts upregulation of several elements in the Notch signaling cascade. Downregulation of NOTCH4, but not NOTCH1, prevented the positive effect of NCoR1 knockdown on spheroid outgrowth. Collectively, these data indicate that decreasing NCOR1 expression is an attractive approach to promote angiogenic function.
2024-02-12 | GSE237653 | GEO
Project description:Thyroid hormones (THs) play a critical role in development and throughout adulthood. THs act through the thyroid receptor (TR), which binds to the TH response element (TRE) to regulate the expression of target genes. Although TH action has been studied for decades, surprisingly few TREs have been well validated and characterized. In this study we used chromatin immunoprecipitation followed by microarray analysis (ChIP-chip) to identify TR-binding sites in juvenile (postnatal day 15) mice liver. Microarray analysis revealed twelve TR-binding sites consistent between all analyzed samples. In silico analysis was carried out to search for moderately conserved classic TRE sequences within these novel binding regions, which led to the identification of six candidate TREs within three binding regions. Luciferase reporter assays confirmed the presence of a TRE in the promoter region of DEAD (Asp-Glu-Ala-Asp) box polypeptide 54 (Ddx54) and thyroid hormone responsive SPOT14 (Thrsp). The TR/retinoid X receptor (RXR) heterodimer and RXR homodiner were shown to bind the promoter region of Ddx54 and drive gene expression in the presence of 9-cis-retinoic acid (9cRA). The promoter region of Thrsp was shown to allow binding of the TR/RXR heterodimer, and both T3 and 9cRA were able to significantly increase luciferase activity. The RXR homodimer was also able to bind the response element in the promoter region of Thrsp and increase luciferase activity. Overall, ChIP-chip analysis revealed a relatively limited number of TR-binding sites in juvenile mouse liver despite previous studies showing that numerous genes can be affected by TH disruption at that developmental stage, suggesting that TH action may also be mediated through other intermediates. Collectively the results provide an important step towards characterizing TR-binding sites and identifying the underlying drivers of TR-gene regulation. Three samples were analyzed (total input and immunoprecipitated for each samples).
2013-11-16 | E-GEOD-52417 | biostudies-arrayexpress