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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 -
Cell Host & Microbe Jul 2021Toxoplasma gondii translocates effector proteins into its host cell to subvert various host pathways. T. gondii effector TgIST blocks the transcription of...
Toxoplasma gondii translocates effector proteins into its host cell to subvert various host pathways. T. gondii effector TgIST blocks the transcription of interferon-stimulated genes to reduce immune defense. Interferons upregulate numerous genes, including protein kinase R (PKR), which induce necrosome formation to activate mixed-lineage-kinase-domain-like (MLKL) pseudokinase and induce necroptosis. Whether these interferon functions are targeted by Toxoplasma is unknown. Here, we examine secreted effectors that localize to the host cell nucleus and find that the chronic bradyzoite stage secretes effector TgNSM that targets the NCoR/SMRT complex, a repressor for various transcription factors, to inhibit interferon-regulated genes involved in cell death. TgNSM acts with TgIST to block IFN-driven expression of PKR and MLKL, thus preventing host cell necroptotic death and protecting the parasite's intracellular niche. The mechanism of action of TgNSM uncovers a role of NCoR/SMRT in necroptosis, assuring survival of intracellular cysts and chronic infection.
Topics: HeLa Cells; Host-Parasite Interactions; Humans; Necroptosis; Nuclear Receptor Co-Repressor 2; Protein Kinases; Protozoan Proteins; Toxoplasma; Toxoplasmosis; eIF-2 Kinase
PubMed: 34043960
DOI: 10.1016/j.chom.2021.04.016 -
Neuropharmacology May 2014Epigenetic modifications are a central mechanism for regulating chromatin structure and gene expression in the brain. A wide array of histone- and DNA-modifying enzymes... (Review)
Review
Epigenetic modifications are a central mechanism for regulating chromatin structure and gene expression in the brain. A wide array of histone- and DNA-modifying enzymes have been identified as critical regulators of neuronal function, memory formation, and as causative agents in neurodevelopmental and neuropsychiatric disorders. Chromatin modifying enzymes are frequently incorporated into large multi-protein co-activator and co-repressor complexes, where the activity of multiple enzymes is both spatially and temporally coordinated. In this review, we discuss negative regulation of gene expression by co-repressor complexes, and the role of co-repressors and their binding partners in neuronal function, memory, and disease.
Topics: Animals; Brain; Chromatin Assembly and Disassembly; Co-Repressor Proteins; Epigenetic Repression; Gene Expression Regulation; Humans; Memory; Mi-2 Nucleosome Remodeling and Deacetylase Complex; Models, Biological; Nerve Tissue Proteins; Nervous System Diseases; Neurons; Nuclear Receptor Co-Repressor 1; Nuclear Receptor Co-Repressor 2; Repressor Proteins; Sin3 Histone Deacetylase and Corepressor Complex; Transcription, Genetic
PubMed: 24440532
DOI: 10.1016/j.neuropharm.2014.01.003 -
Proceedings of the National Academy of... Aug 2022Brown 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...
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 require histone deacetylase 3 (HDAC3). HDAC3 exists in tight association with nuclear receptor corepressors (NCoRs) NCoR1 and NCoR2 (also known as silencing mediator of retinoid and thyroid receptors [SMRT]), but the 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 NCoR1/2 BAT-dKO and HDAC3 BAT-KO mice. Despite these commonalities, loss of NCoR1/2 in BAT does not phenocopy the cold sensitivity observed in HDAC3 BAT-KO, nor does loss of either corepressor alone. Instead, BAT lacking NCoR1/2 is inflamed, particularly with respect to the interleukin-17 axis that increases thermogenic capacity by enhancing innervation. Integration of BAT RNA sequencing and chromatin immunoprecipitation sequencing data revealed that NCoR1/2 directly regulate , 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 stimulation of HDAC3 activity in the control of thermogenesis.
Topics: Adipose Tissue, Brown; Animals; Histone Deacetylases; Inflammation; Mice; Mice, Knockout; Nuclear Receptor Co-Repressor 1; Nuclear Receptor Co-Repressor 2; Receptors, Retinoic Acid; Thermogenesis; Uncoupling Protein 1
PubMed: 35939699
DOI: 10.1073/pnas.2205276119 -
Microorganisms Sep 2023When compared with bacteria, relatively little is known about the restriction-modification (RM) systems of archaea, particularly those in taxa outside of the...
When compared with bacteria, relatively little is known about the restriction-modification (RM) systems of archaea, particularly those in taxa outside of the haloarchaea. To improve our understanding of archaeal RM systems, we surveyed REBASE, the restriction enzyme database, to catalog what is known about the genes and activities present in the 519 completely sequenced archaeal genomes currently deposited there. For 49 (9.4%) of these genomes, we also have methylome data from Single-Molecule Real-Time (SMRT) sequencing that reveal the target recognition sites of the active mA and mC DNA methyltransferases (MTases). The gene-finding pipeline employed by REBASE is trained primarily on bacterial examples and so will look for similar genes in archaea. Nonetheless, the organizational structure and protein sequence of RM systems from archaea are highly similar to those of bacteria, with both groups acquiring systems from a shared genetic pool through horizontal gene transfer. As in bacteria, we observe numerous examples of "persistent" DNA MTases conserved within archaeal taxa at different levels. We experimentally validated two homologous members of one of the largest "persistent" MTase groups, revealing that methylation of C(mC)WGG sites may play a key epigenetic role in Crenarchaea. Throughout the archaea, genes encoding mA, mC, and mC DNA MTases, respectively, occur in approximately the ratio 4:2:1.
PubMed: 37894082
DOI: 10.3390/microorganisms11102424 -
Genes & Development Apr 2013Epigenetic regulation of gene expression is strongly influenced by the accessibility of nucleosomal DNA or the state of chromatin compaction. In this context,... (Review)
Review
Epigenetic regulation of gene expression is strongly influenced by the accessibility of nucleosomal DNA or the state of chromatin compaction. In this context, coregulators, including both coactivators and corepressors, are pivotal intermediates that bridge chromatin-modifying enzymes and transcription factors. NCoR1 (nuclear receptor corepressor) and SMRT (silencing mediator of retinoic acid and thyroid hormone receptor) are among the best-characterized corepressors from a molecular point of view. These coregulators have conserved orthologs in lower organisms, which underscores their functional importance. Here we summarize the results from recent in vivo studies that reveal the wide-ranging roles of NCoR1 and SMRT in developmental as well as homeostatic processes, including metabolism, inflammation, and circadian rhythms. We also discuss the potential implications of NCoR1 and SMRT regulation of pathways ranging from genomic stability and carcinogenesis to metabolic diseases such as type 2 diabetes.
Topics: Animals; Gene Expression Regulation; Homeostasis; Humans; Nuclear Receptor Co-Repressor 1; Nuclear Receptor Co-Repressor 2
PubMed: 23630073
DOI: 10.1101/gad.214023.113 -
Biochimie Oct 2012Adiponectin has been receiving a great deal of attention due to its potential therapeutic use for metabolic and cardiovascular disorders. Adiponectin expression levels... (Review)
Review
Adiponectin has been receiving a great deal of attention due to its potential therapeutic use for metabolic and cardiovascular disorders. Adiponectin expression levels and multimerization are down-regulated in obesity and up-regulated by insulin sensitizers such as thiazolidinediones (TZDs), metformin, sulfonylurea and resveratrol (RSV). The precise mechanisms underlying adiponectin up- and down-regulation remain largely unknown, but recent studies indicate that the cellular and plasma levels of adiponectin could be regulated at both transcriptional and post-transcriptional levels. At the post-translational level, TZDs and resveratrol promote adiponectin levels and multimerization via up-regulation of disulfide-bond-A oxidoreductase-like protein (DsbA-L). Adiponectin levels are also stimulated by FOXO1 and AMP-activated protein kinase (AMPK), and are suppressed by PKA or silencing mediator of retinoid and thyroid hormone receptors (SMRT). Since multimerization is important not only for adiponectin function but also for stability, increasing adiponectin multimerization has become a promising drug target for the treatment of metabolic diseases and other related disorders.
Topics: Adiponectin; Animals; Down-Regulation; Humans; PPAR gamma; Protein Multimerization; Small Molecule Libraries; Up-Regulation
PubMed: 22342903
DOI: 10.1016/j.biochi.2012.01.008 -
Nuclear Receptor Signaling 2003The ability of NR LBDs to transfer repression function to a heterologous DNA binding domain, and the cross-squelching of repression by untethered LBDs, has suggested...
The ability of NR LBDs to transfer repression function to a heterologous DNA binding domain, and the cross-squelching of repression by untethered LBDs, has suggested that repression is mediated by interactions with putative cellular corepressor proteins. The yeast-two hybrid screen for protein interactors has proven to be the key to the isolation and characterization of corepressors. This short review will focus on N-CoR and SMRT.
PubMed: 16604174
DOI: 10.1621/nrs.01001 -
American Journal of Clinical and... 2014Nuclear receptor corepressor (NCoR) and silencing mediator for retinoid and thyroid hormone receptors (SMRT) function as corepressors for diverse transcription factors... (Review)
Review
Nuclear receptor corepressor (NCoR) and silencing mediator for retinoid and thyroid hormone receptors (SMRT) function as corepressors for diverse transcription factors including nuclear receptors such as estrogen receptors and androgen receptors. Deregulated functions of NCoR and SMRT have been observed in many types of cancers and leukemias. NCoR and SMRT directly bind to transcription factors and nucleate the formation of stable complexes that include histone deacetylase 3, transducin b-like protein 1/TBL1-related protein 1, and G-protein pathway suppressor 2. These NCoR/SMRT-interacting proteins also show deregulated functions in cancers. In this review, we summarize the literature on the mechanism, regulation, and function of the core components of NCoR/SMRT complexes in the context of their involvement in cancers and leukemias. While the current studies support the view that the corepressors are promising targets for cancer treatment, elucidation of the mechanisms of corepressors involved in individual types of cancers is likely required for effective therapy.
PubMed: 25374920
DOI: No ID Found