-
International Journal of Oncology May 2001p53-binding consensus-like sequence (T3SF) is located in the murine promoter region of tissue inhibitor of metalloproteinase 3 gene. To identify the genes that encode...
p53-binding consensus-like sequence (T3SF) is located in the murine promoter region of tissue inhibitor of metalloproteinase 3 gene. To identify the genes that encode proteins that bind to T3SF DNA sequence, we screened a cDNA library using the Southwestern technique. The SMRT gene was cloned as one of the candidates. Addition of antibody against SMRT reduced the intensity of a band that is supposed to contain SMRT in electrophoresis mobility shift assay, although antibody against p53 had no effect. Ultraviolet (UV)-irradiation reduced the intensity of the SMRT complex whereas p53 complex was stabilized by UV-irradiation. These results suggest that SMRT may bind to T3SF sequence in p53-independent manner and dissociate from the sequence by UV irradiation.
Topics: Binding Sites; Blotting, Southern; Blotting, Western; DNA-Binding Proteins; Electrophoresis, Agar Gel; Gene Library; Humans; Nuclear Receptor Co-Repressor 2; Repressor Proteins; Tissue Inhibitor of Metalloproteinase-3; Tumor Cells, Cultured; Tumor Suppressor Protein p53
PubMed: 11295045
DOI: 10.3892/ijo.18.5.985 -
Cell Jul 2020The most aggressive B cell lymphomas frequently manifest extranodal distribution and carry somatic mutations in the poorly characterized gene TBL1XR1. Here, we show that...
The most aggressive B cell lymphomas frequently manifest extranodal distribution and carry somatic mutations in the poorly characterized gene TBL1XR1. Here, we show that TBL1XR1 mutations skew the humoral immune response toward generating abnormal immature memory B cells (MB), while impairing plasma cell differentiation. At the molecular level, TBL1XR1 mutants co-opt SMRT/HDAC3 repressor complexes toward binding the MB cell transcription factor (TF) BACH2 at the expense of the germinal center (GC) TF BCL6, leading to pre-memory transcriptional reprogramming and cell-fate bias. Upon antigen recall, TBL1XR1 mutant MB cells fail to differentiate into plasma cells and instead preferentially reenter new GC reactions, providing evidence for a cyclic reentry lymphomagenesis mechanism. Ultimately, TBL1XR1 alterations lead to a striking extranodal immunoblastic lymphoma phenotype that mimics the human disease. Both human and murine lymphomas feature expanded MB-like cell populations, consistent with a MB-cell origin and delineating an unforeseen pathway for malignant transformation of the immune system.
Topics: Animals; Basic-Leucine Zipper Transcription Factors; Chromatin; Germinal Center; Histone Deacetylases; Humans; Immunologic Memory; Lymphoma, Large B-Cell, Diffuse; Mice; Mice, Inbred C57BL; Mice, Knockout; Mutagenesis, Site-Directed; Nuclear Proteins; Nuclear Receptor Co-Repressor 2; Precursor Cells, B-Lymphoid; Protein Binding; Proto-Oncogene Proteins c-bcl-6; RNA Interference; RNA, Small Interfering; Receptors, Cytoplasmic and Nuclear; Repressor Proteins; Transcription, Genetic
PubMed: 32619424
DOI: 10.1016/j.cell.2020.05.049 -
Nature Cancer Jun 2022Resistance to antitumor treatment contributes to patient mortality. Functional proteomic screening of organoids derived from chemotherapy-treated patients with breast...
Resistance to antitumor treatment contributes to patient mortality. Functional proteomic screening of organoids derived from chemotherapy-treated patients with breast cancer identified nuclear receptor corepressor 2 (NCOR2) histone deacetylase as an inhibitor of cytotoxic stress response and antitumor immunity. High NCOR2 in the tumors of patients with breast cancer predicted chemotherapy refractoriness, tumor recurrence and poor prognosis. Molecular studies revealed that NCOR2 inhibits antitumor treatment by regulating histone deacetylase 3 (HDAC3) to repress interferon regulatory factor 1 (IRF-1)-dependent gene expression and interferon (IFN) signaling. Reducing NCOR2 or impeding its epigenetic activity by modifying its interaction with HDAC3 enhanced chemotherapy responsiveness and restored antitumor immunity. An adeno-associated viral NCOR2-HDAC3 competitor potentiated chemotherapy and immune checkpoint therapy in culture and in vivo by permitting transcription of IRF-1-regulated proapoptosis and inflammatory genes to increase IFN-γ signaling. The findings illustrate the utility of patient-derived organoids for drug discovery and suggest that targeting stress and inflammatory-repressor complexes such as NCOR2-HDAC3 could overcome treatment resistance and improve the outcome of patients with cancer.
Topics: Antineoplastic Agents; Breast Neoplasms; Cell Line, Tumor; Early Detection of Cancer; Female; Humans; Neoplasm Recurrence, Local; Nuclear Receptor Co-Repressor 2; Organoids; Proteomics
PubMed: 35618935
DOI: 10.1038/s43018-022-00375-0 -
FASEB Journal : Official Publication of... Jul 2020Peroxisome proliferator-activated receptor alpha (PPARα, NR1C1) belongs to a large family of ligand-dependent nuclear receptors (NRs). It is one of the best studied NRs... (Review)
Review
Peroxisome proliferator-activated receptor alpha (PPARα, NR1C1) belongs to a large family of ligand-dependent nuclear receptors (NRs). It is one of the best studied NRs which controls the lipid metabolism (mainly fatty acid oxidation) and inflammation, and has been a promising target for treating metabolic disorders such as fatty liver and cardiometabolic diseases. The function of PPARα relies on its interaction with various coregulators upon different stimulating contexts, and, thereby, activates or represses its transcription targets in a gene-selective manner. Understanding the transcription factor and coregulator network underlying the PPARα regulation is prerequisite to decipher its gene- and context-selectivity for designing better therapeutic ligands. In this review, we will summarize current knowledge of PPARα coregulator network, with major focus on a relatively well-studied corepressor complex containing core subunits of nuclear receptor corepressor (NCOR or NCOR1), silencing mediator of retinoic acid and thyroid hormone receptor (SMRT or NCOR2), G-protein suppressor 2 (GPS2), transducin β-like protein 1 (TBL1 or TBL1X), TBL-related 1 (TBLR1 or TBL1XR1), and the catalytic core of histone deacetylase 3 (HDAC3). We will mainly review the molecular events of the complex and sub-complexes in controlling the liver metabolism. We will also discuss the potential perturbation of the subunit expression in human livers during liver metabolic disorder progression which potentially defines the patient disease susceptibility and drug responses.
Topics: Animals; Gene Regulatory Networks; Humans; Liver; Nuclear Receptor Co-Repressor 1; Nuclear Receptor Co-Repressor 2; PPAR alpha
PubMed: 32396271
DOI: 10.1096/fj.202000055RR -
Wnt5a controls Notch1 signaling through CaMKII-mediated degradation of the SMRT corepressor protein.The Journal of Biological Chemistry Oct 2012Serine-threonine Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) is the key component in noncanonical Wnt5a signaling and has been shown to regulate its...
Serine-threonine Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) is the key component in noncanonical Wnt5a signaling and has been shown to regulate its signaling. In this study, we found that CaMKII induced by Wnt5a remarkably reduced the protein stability of the silencing mediator of retinoic acid and thyroid hormone receptor (SMRT), a co-repressor of Notch signaling, through proteasomal degradation. Wnt5a was found to enhance Notch1 intracellular domain (Notch1-IC) transcription activity, which could be inhibited by treatment with KN93, a CaMKII inhibitor. The kinase activity of CaMKII was essential for the activation of Notch signaling. We also determined that CaMKII could enhance the association between Notch1-IC and RBP-Jk. Furthermore, the physical association between RBP-Jk and SMRT was substantially suppressed by CaMKII. We demonstrated that CaMKII directly bound and phosphorylated SMRT at Ser-1407, thereby facilitating SMRT translocation from the nucleus to the cytoplasm and proteasome-dependent degradation. These results suggest that CaMKII down-regulated the protein stability of SMRT through proteasomal degradation.
Topics: Animals; Basic Helix-Loop-Helix Transcription Factors; Calcium-Calmodulin-Dependent Protein Kinase Type 2; Down-Regulation; Genes, Reporter; HEK293 Cells; Homeodomain Proteins; Humans; Immunoglobulin J Recombination Signal Sequence-Binding Protein; Luciferases; Mice; Nuclear Receptor Co-Repressor 2; Phosphorylation; Promoter Regions, Genetic; Protein Binding; Protein Processing, Post-Translational; Protein Structure, Tertiary; Proteolysis; Proto-Oncogene Proteins; Receptor, Notch1; Repressor Proteins; Transcription Factor HES-1; Transcriptional Activation; Ubiquitination; Wnt Proteins; Wnt Signaling Pathway; Wnt-5a Protein
PubMed: 22888005
DOI: 10.1074/jbc.M112.356048 -
The EMBO Journal Aug 2000We present evidence that both corepressors SMRT and N-CoR exist in large protein complexes with estimated sizes of 1.5-2 MDa in HeLa nuclear extracts. Using a...
We present evidence that both corepressors SMRT and N-CoR exist in large protein complexes with estimated sizes of 1.5-2 MDa in HeLa nuclear extracts. Using a combination of conventional and immunoaffinity chromatography, we have successfully isolated a SMRT complex and identified histone deacetylase 3 (HDAC3) and transducin (beta)-like I (TBL1), a WD-40 repeat-containing protein, as the subunits of the purified SMRT complex. We show that the HDAC3-containing SMRT and N-CoR complexes can bind to unliganded thyroid hormone receptors (TRs) in vitro. We demonstrate further that in Xenopus oocytes, both SMRT and N-CoR also associate with HDAC3 in large protein complexes and that injection of antibodies against HDAC3 or SMRT/N-CoR led to a partial relief of repression by unliganded TR/RXR. These findings thus establish both SMRT and N-CoR complexes as bona fide HDAC-containing complexes and shed new light on the molecular pathways by which N-CoR and SMRT function in transcriptional repression.
Topics: Animals; Blotting, Western; Cell Nucleus; Chromatography, Affinity; Chromatography, Gel; Chromatography, Ion Exchange; Cloning, Molecular; DNA-Binding Proteins; HeLa Cells; Histone Deacetylases; Humans; Ligands; Nuclear Proteins; Nuclear Receptor Co-Repressor 1; Nuclear Receptor Co-Repressor 2; Oocytes; Plasmids; Protein Binding; Receptors, Retinoic Acid; Receptors, Thyroid Hormone; Recombinant Proteins; Repressor Proteins; Transcription, Genetic; Two-Hybrid System Techniques; Xenopus
PubMed: 10944117
DOI: 10.1093/emboj/19.16.4342 -
PloS One 2022Silencing Mediator of Retinoid and Thyroid hormone receptors (SMRT; NCoR2) is a transcriptional corepressor (CoR) which has been recognized as an important player in the...
BACKGROUND
Silencing Mediator of Retinoid and Thyroid hormone receptors (SMRT; NCoR2) is a transcriptional corepressor (CoR) which has been recognized as an important player in the regulation of hepatic lipogenesis and in somatic development in mouse embryo. SMRT protein is also widely expressed in mouse connective tissues, for example adipocytes and muscle. We recently reported that mice with global deletion of SMRT develop significant obesity and muscle wasting which are independent from thyroid hormone (TH) signaling and thermogenesis. However, the tissue specific role of SMRT in skeletal muscle is still not clear.
METHODS
To clarify role of SMRT in muscle differentiation, we made myogenic C2C12 clones which lack SMRT protein (C2C12-SKO) by using CRISPR-Cas9. Wild-type C2C12 (C2C12-WT) and C2C12-SKO cells were cultured in differentiation medium, and the resulting gene and protein profiles were compared between the two cell lines both before and after differentiation. We also analyzed muscle tissues which were dissected from whole body SMRT knockout (KO) mice and their controls.
RESULTS
We found significant up-regulation of muscle specific β-oxidation markers; Peroxisome proliferator-activated receptor δ (PPARδ) and PPARγ coactivator-1α (PGC-1α) in the C2C12-SKO cells, suggesting that the cells had a similar gene profile to what is found in exercised rodent skeletal muscle. On the other hand, confocal microscopic analysis showed the significant loss of myotubes in C2C12-SKO cells similar to the morphology found in immature myoblasts. Proteomics analysis also confirmed that the C2C12-SKO cells had higher expression of markers of fibrosis (ex. Collagen1A1; COL1A1 and Fibroblast growth factor-2; FGF-2), indicating the up-regulation of Transforming growth factor-β (TGF-β) receptor signaling. Consistent with this, treatment with a specific TGF-β receptor inhibitor ameliorated both the defects in myotube differentiation and fibrosis.
CONCLUSION
Taken together, we demonstrate that SMRT functions as a pivotal transcriptional mediator for both β-oxidation and the prevention for the fibrosis via TGF-β receptor signaling in the differentiation of C2C12 myoblasts. In contrast to the results from C2C12 cells, SMRT does not appear to play a role in adult skeletal muscle of whole body SMRT KO mice. Thus, SMRT plays a significant role in the differentiation of myoblasts.
Topics: Animals; Mice; Cell Differentiation; Fibroblast Growth Factor 2; Fibrosis; Muscle Fibers, Skeletal; Muscle, Skeletal; PPAR delta; Nuclear Receptor Co-Repressor 2
PubMed: 36454860
DOI: 10.1371/journal.pone.0277830 -
Molecular and Cellular Biochemistry Apr 2001The Silencing-Mediator for Retinoid/Thyroid hormone receptors (SMRT) interacts with, and mediates transcriptional repression by, a variety of eukaryotic transcription...
The Silencing-Mediator for Retinoid/Thyroid hormone receptors (SMRT) interacts with, and mediates transcriptional repression by, a variety of eukaryotic transcription factors, including the nuclear hormone receptors. The ability of SMRT to function as a transcriptional 'corepressor' is regulated by a variety of signal transduction pathways. We report here that SMRT is a phosphoprotein in vivo, and is also phosphorylated in vitro by unfractionated cell extracts. A major site of phosphorylation of SMRT is a protein kinase CK2 motif centered on serine 1492, and located within a C-terminal SMRT domain that mediates interaction of the corepressor with the nuclear hormone receptors. Phosphorylation of SMRT by CK2 stabilizes the ability of the SMRT protein to interact with nuclear hormone receptors. Our results indicate that SMRT is a member of an expanding family of transcriptional regulators that are modified, and potentially regulated, in response to protein kinase CK2.
Topics: Amino Acid Sequence; Animals; Casein Kinase II; Cell Line; DNA-Binding Proteins; Dose-Response Relationship, Drug; Fibroblasts; Gene Expression Regulation, Enzymologic; Haplorhini; Microscopy, Confocal; Molecular Sequence Data; Nuclear Receptor Co-Repressor 2; Phosphorylation; Plasmids; Protein Binding; Protein Serine-Threonine Kinases; Protein Structure, Tertiary; Receptors, Thyroid Hormone; Recombinant Proteins; Repressor Proteins; Time Factors; Transcription, Genetic; Transfection
PubMed: 11451368
DOI: 10.1023/a:1011087910699 -
Molecular Metabolism Nov 2021The nuclear receptor corepressor 1 (NCOR1) and the silencing mediator of retinoic acid and thyroid hormone (SMRT, also known as NCOR2) play critical and specific roles...
OBJECTIVE
The nuclear receptor corepressor 1 (NCOR1) and the silencing mediator of retinoic acid and thyroid hormone (SMRT, also known as NCOR2) play critical and specific roles in nuclear receptor action. NCOR1, both in vitro and in vivo specifically regulates thyroid hormone (TH) action in the context of individual organs such as the liver, and systemically in the context of the hypothalamic-pituitary-thyroid (HPT) axis. In contrast, selective deletion of SMRT in the liver or globally has shown that it plays very little role in TH signaling. However, both NCOR1 and SMRT have some overlapping roles in hepatic metabolism and lipogenesis. Here, we determine the roles of NCOR1 and SMRT in global physiologic function and find if SMRT could play a compensatory role in the regulation of TH action, globally.
METHODS
We used a postnatal deletion strategy to disrupt both NCOR1 and SMRT together in all tissues at 8-9 weeks of age in male and female mice. This was performed using a tamoxifen-inducible Cre recombinase (UBC-Cre-ERT2) to KO (knockout) NCOR1, SMRT, or NCOR1 and SMRT together. We used the same strategy to KO HDAC3 in male and female mice of the same age. Metabolic parameters, gene expression, and thyroid function tests were analyzed.
RESULTS
Surprisingly, adult mice that acquired NCOR1 and SMRT deletion rapidly became hypoglycemic and hypothermic and perished within ten days of deletion of both corepressors. Postnatal deletion of either NCOR1 or SMRT had no impact on mortality. NCOR1/SMRT KO mice rapidly developed hepatosteatosis and mild elevations in liver function tests. Additionally, alterations in lipogenesis, beta oxidation, along with hepatic triglyceride and glycogen levels suggested defects in hepatic metabolism. The intestinal function was intact in the NCOR1/SMRT knockout (KO) mice. The KO of HDAC3 resulted in a distinct phenotype from the NCOR1/SMRT KO mice, whereas none of the HDAC3 KO mice succumbed after tamoxifen injection.
CONCLUSIONS
The KO of NCOR1 and SMRT rapidly leads to significant metabolic abnormalities that do not survive - including hypoglycemia, hypothermia, and weight loss. Hepatosteatosis rapidly developed along with alterations in hepatic metabolism suggesting a contribution to the dramatic phenotype from liver injury. Glucose production and absorption were intact in NCOR1/SMRT KO mice, demonstrating a multifactorial process leading to their demise. HDAC3 KO mice have a distinct phenotype from the NCOR1/SMRT KO mice-which implies that NCOR1/SMRT together regulate a critical pathway that is required for survival in adulthood and is separate from HDAC3.
Topics: Animals; Female; Homeostasis; Male; Mice; Mice, Knockout; Mice, Transgenic; Nuclear Receptor Co-Repressor 1; Nuclear Receptor Co-Repressor 2
PubMed: 34390859
DOI: 10.1016/j.molmet.2021.101315 -
PloS One 2022Tokay Gecko (Gekko gecko) is a rare and endangered medicinal animal in China. Its dry body has been used as an anti-asthmatic agent for two thousand years. To date, the...
Tokay Gecko (Gekko gecko) is a rare and endangered medicinal animal in China. Its dry body has been used as an anti-asthmatic agent for two thousand years. To date, the genome and transcriptome of this species remain poorly understood. Here, we adopted single molecule real-time (SMRT) sequencing to obtain full-length transcriptome data and characterized the transcriptome structure. We identified 882,273 circular consensus (CCS) reads, including 746,317 full-length nonchimeric (FLNC) reads. The transcript cluster analysis revealed 212,964 consensus sequences, including 203,994 high-quality isoforms. In total, 111,372 of 117,888 transcripts were successfully annotated against eight databases (Nr, eggNOG, Swiss-Prot, GO, COG, KOG, Pfam and KEGG). Furthermore, 23,877 alternative splicing events, 169,128 simple sequence repeats (SSRs), 10,437 lncRNAs and 7,932 transcription factors were predicted across all transcripts. To our knowledge, this report is the first to document the G. gecko transcriptome using SMRT sequencing. The full-length transcript data might accelerate transcriptome research and lay the foundation for further research on G. gecko.
Topics: Alternative Splicing; Animals; Genome; High-Throughput Nucleotide Sequencing; Lizards; Microsatellite Repeats; Protein Isoforms; RNA; RNA, Long Noncoding; Sequence Analysis, RNA; Transcription Factors; Transcriptome
PubMed: 35213661
DOI: 10.1371/journal.pone.0264499