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
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).
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.
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.
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.
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. This SuperSeries is composed of the SubSeries listed below.
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
Project description:We show that knock-in mutations of the nuclear corepressor SMRT in C57Bl6 mice (SMRTmRID) produces a novel respiratory distress syndrome (RDS) due to prematurity of the type I pneumocyte. Treatment with the anti-thyroid hormone drug, propylthiouracil (PTU), completely rescues the SMRT-induced RDS, suggesting an unrecognized and essential role for the thyroid hormone receptor (TR) in lung development. We show that TR and SMRT control type I pneumocyte differentiation through Klf2, which in turn appears to directly activate the type I pneumocyte gene program. Conversely, mice without lung Klf2 lack mature type I pneumocytes and die shortly after birth, closely recapitulating the SMRTmRID phenotype. These results identify a second nuclear receptor, the TR, in type I pneumocyte differentiation and suggest a new type of therapeutic option in the treatment of glucocorticoid non-responsive RDS. Total RNA was obtained from WT and SMRT-RID E18.5 lungs of embryos from mothers treated with Diet containing 0.15% PTU or control chow for 2 days (from E16.5).
Project description:SMRT (silencing mediator of retinoid and thyroid hormone receptors) is recruited by numerous transcription factors to mediate lineage and signal dependent transcriptional repression. We generated a knock-in mutation in the receptor interaction domain (RID) of SMRT (SMRTmRID) that solely disrupts its interaction with nuclear hormone receptors. SMRTmRID-derived 3T3-MEFs display a dramatically increased adipogenic capacity and accelerated differentiation rate. We measured global gene expression in wild-type versus SMRTmRID-derived 3T3-MEFs in the undifferentiated state to examine which pathways were altered. Our results demonstrate that SMRT-RID dependent repression is a key determinant of the adipogenic set point. Experiment Overall Design: 3T3 cells derived from wild-type and SMRT RID MEFs were cultured under pre-differentiated conditions prior to harvesting for RNA.
Project description:ChIP-seq of mouse embryonic fibroblast-adipose like cell line 3T3-L1 to identify binding sites of NCoR1 and SMRT following induction of differentiation, and RNA Pol-II after SMRT knock down