Project description:The nuclear corepressors NCOR1 and NCOR2 interact with transcription factors involved in B cell development and potentially link these factors to alterations in chromatin structure and gene expression. Herein we demonstrate that NCOR1/2 deletion limits B cell differentiation via impaired recombination, attenuates pre-BCR-signaling, and enhances STAT5-dependent transcription. Furthermore, NCOR1/2-deficient B cells exhibited derepression of EZH2-repressed gene modules, including the p53 pathway. These alterations resulted in aberrant Rag1 and Rag2 expression and accessibility in proliferating cells. Whole-genome sequencing of Ncor1/2 DKO B cells identified increased number of structural variants compared to wildtype B cells with cryptic recombination signal sequences. Finally, deletion of Ncor1 alleles in mice facilitated leukemic transformation, while human leukemias with less NCOR1 correlated with worse survival. NCOR1 mutations in human leukemia correlated with increased RAG expression and increased number of structural variants. These studies illuminate how the corepressors NCOR1/2 regulate B cell differentiation and provide insights into how NCOR1/2 mutations may promote B cell transformation.
Project description:Here, we demonstrate that upon inhibition of the Fgf/Erk pathway in mouse trophoblast stem cells (TSCs), the Ets2 repressor factor (Erf) interacts with components of the Nuclear Receptor Corepressor Complex 1 and 2 (NCoR1 and NCoR2). Upon attenuation of Fgf signalling, unphosphorylated, nuclear Erf recruits the NCoR1/2 complex to key trophoblast genes, brings about their transcriptional silencing and facilitates differentiation and placental development.
Project description:Brown adipose tissue (BAT) is a key thermogenic organ, whose expression of Uncoupling Protein 1 (UCP1) and ability to maintain body temperature in response to acute cold exposure requires histone deacetylase 3 (HDAC3). HDAC3 exists in tight association with nuclear receptor corepressors NCoR1 and NCoR2(also known as Silencing Mediator of Retinoid and Thyroid Receptors, or SMRT), butthe functions of NCoR1/2 in BAT have not been established.Here we report that, as expected, genetic loss of NCoR1/2 in BAT (NCoR1/2 BAT-dKO) leads to loss of HDAC3 activity. In addition, HDAC3 is no longer bound at its physiological genomic sites in the absence of NCoR1/2, leading to a shared deregulation of BAT lipid metabolism between the NCoR1/2 BAT-dKO and HDAC3 BAT KO mice. Despite these commonalities, however, loss of NCoR1/2 in BAT does not phenocopy the cold sensitivity observed in the HDAC3 BAT-KO, nor does loss of either corepressor alone. Instead, BAT lacking NCoR1/2 is inflamed, particularly with respect to the IL-17 axis that increases thermogenic capacity by enhancing innervation. Integration of BAT RNA-seq and ChIP-seq data revealed that NCoR1/2 directly regulate Mmp9, which integrates extracellular matrix remodeling and inflammation. These findings reveal pleiotropic functions of the NCoR/HDAC3 corepressor complex in BAT, such that HDAC3-independent suppression of BAT inflammation counterbalances their stimulation of HDAC3 activity in the control of thermogenesis.
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: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:Histone deacetylase 3 (HDAC3) is an epigenome-modifying enzyme that is required for normal mouse development and tissue-specific functions. In vitro, HDAC3 protein itself has minimal enzyme activity, but gains its histone deacetylation function from stable association with the conserved deacetylase activation domain (DAD) contained in nuclear receptor corepressors NCOR1 and SMRT. Here we show that HDAC3 enzyme activity is undetectable in mice bearing point mutations in the DAD of both NCOR1 and SMRT (NS-DADm), despite normal levels of HDAC3 protein. Local histone acetylation is increased, and genomic HDAC3 recruitment is reduced though not abrogated. Remarkably, the NS-DADm mice are born and live to adulthood, whereas genetic deletion of HDAC3 is embryonic lethal. These findings demonstrate that nuclear receptor corepressors are required for HDAC3 enzyme activity in vivo, and suggest that a deacetylase-independent function of HDAC3 may be required for life. This SuperSeries is composed of the SubSeries listed below. Refer to individual Series.
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).