ABSTRACT
Runt-related transcription factor 1 (RUNX1) plays an important role in normal haematopoietic cell development and function, and its function is frequently disrupted in leukaemia. RUNX1 is widely recognised as a sequence-specific DNA binding factor that recognises the motif 5'-TG(T/C)GGT-3' in promoter and enhancer regions of its target genes. Moreover, RUNX1 fusion proteins, such as RUNX1-ETO formed by the t(8;21) translocation, retain the ability to recognise and bind to this sequence to elicit atypical gene regulatory effects on bona fide RUNX1 targets. However, our analysis of publicly available RUNX1 chromatin immunoprecipitation sequencing (ChIP-Seq) data has provided evidence challenging this dogma, revealing that this motif-specific model of RUNX1 recruitment and function is incomplete. Our analyses revealed that the majority of RUNX1 genomic localisation occurs outside of promoters, that 20% of RUNX1 binding sites lack consensus RUNX motifs, and that binding in the absence of a cognate binding site is more common in promoter regions compared to distal sites. Reporter assays demonstrate that RUNX1 can drive promoter activity in the absence of a recognised DNA binding motif, in contrast to RUNX1-ETO. RUNX1-ETO supresses activity when it is recruited to promoters containing a sequence specific motif, while interestingly, it binds but does not repress promoters devoid of a RUNX1 recognition site. These data suggest that RUNX1 regulation of target genes occurs through multiple mechanisms depending on genomic location, the type of regulatory element and mode of recruitment.
Subject(s)
Core Binding Factor Alpha 2 Subunit , Promoter Regions, Genetic , Humans , Binding Sites , Core Binding Factor Alpha 2 Subunit/metabolism , Core Binding Factor Alpha 2 Subunit/genetics , DNA/metabolism , DNA/genetics , Nucleotide Motifs , Protein Binding , Cell Line, TumorABSTRACT
Myopia (short-sightedness), usually caused by excessive elongation of the eye during development, has reached epidemic proportions worldwide. In animal systems including the chicken model, several treatments have been shown to inhibit ocular elongation and experimental myopia. Although diverse in their apparent mechanism of action, each one leads to a reduction in the rate of ocular growth. We hypothesize that a defined set of retinal molecular changes may underlie growth inhibition, irrespective of the treatment agent used. Accordingly, across five well-established but diverse methods of inhibiting myopia, significant overlap is seen in the retinal transcriptome profile (transcript levels and alternative splicing events) in chicks when analyzed by RNA-seq. Within the two major pathway networks enriched during growth inhibition, that of cell signaling and circadian entrainment, transcription factors form the largest functional grouping. Importantly, a large percentage of those genes forming the defined retinal response are downstream targets of the transcription factor EGR1 which itself shows a universal response to all five growth-inhibitory treatments. This supports EGR1's previously implicated role in ocular growth regulation. Finally, by contrasting our data with human linkage and GWAS studies on refractive error, we confirm the applicability of our study to the human condition. Together, these findings suggest that a universal set of transcriptome changes, which sit within a well-defined retinal network that cannot be bypassed, is fundamental to growth regulation, thus paving a way for designing novel targets for myopia therapies.
Subject(s)
Eye/growth & development , Eye/metabolism , Gene Regulatory Networks , Myopia/genetics , Myopia/prevention & control , Transcriptome , Alternative Splicing/drug effects , Animals , Atropine/pharmacology , Chickens , Circadian Rhythm/drug effects , Early Growth Response Protein 1/metabolism , Eye/drug effects , Gene Expression Regulation/drug effects , Gene Regulatory Networks/drug effects , Humans , Janus Kinases/metabolism , Male , Models, Biological , Phosphinic Acids/pharmacology , Pirenzepine/pharmacology , Pyridines/pharmacology , Reproducibility of Results , Retina/drug effects , Retina/growth & development , Retina/metabolism , STAT Transcription Factors/metabolism , Tetrahydronaphthalenes/pharmacology , Time Factors , Transcriptome/drug effectsABSTRACT
Integrins are transmembrane adhesion receptors that play an important role in hematopoiesis by facilitating interactions between hematopoietic cells and extracellular matrix components of the bone marrow and hematopoietic tissues. These interactions are important in regulating the function, proliferation, and differentiation of hematopoietic cells, as well as their homing and mobilization in the bone marrow. Not surprisingly altered expression and function of integrins plays a key role in the development and progression of cancer including leukemias. However, the regulation of integrin gene expression is not well characterized and the mechanisms by which integrin genes are disrupted in cancer remain unclear. Here we demonstrate for the first time that a key regulator of hematopoiesis, RUNX1, binds to and regulates the promoters of both the ITGA6 and ITGB4 genes in myeloid cells. The ITGA6 and ITGB4 integrin genes form the α6ß4 integrin receptor. However, our data indicate that RUNX1 functions differently at these two promoters. RUNX1 regulates ITGA6 through a consensus RUNX1 binding motif in its promoter. In contrast, although the ITGB4 promoter is also activated by RUNX1, it does so in the absence of a recognized consensus RUNX1 binding motif. Furthermore, our data suggest that regulation of ITGB4 may involve interactions between the promoter and upstream regulatory elements.
Subject(s)
Core Binding Factor Alpha 2 Subunit/metabolism , Gene Expression Regulation, Developmental/genetics , Integrin alpha6/metabolism , Integrin beta4/metabolism , Myeloid Cells/metabolism , Cell Differentiation/genetics , Embryo, Mammalian/metabolism , Hematopoiesis/genetics , Hematopoietic Stem Cells/metabolism , Humans , Mutation/genetics , Promoter Regions, Genetic/geneticsABSTRACT
Memory T cells are characterized by their rapid transcriptional programs upon re-stimulation. This transcriptional memory response is facilitated by permissive chromatin, but exactly how the permissive epigenetic landscape in memory T cells integrates incoming stimulatory signals remains poorly understood. By genome-wide ChIP-sequencing ex vivo human CD4(+) T cells, here, we show that the signaling enzyme, protein kinase C theta (PKC-θ) directly relays stimulatory signals to chromatin by binding to transcriptional-memory-responsive genes to induce transcriptional activation. Flanked by permissive histone modifications, these PKC-enriched regions are significantly enriched with NF-κB motifs in ex vivo bulk and vaccinia-responsive human memory CD4(+) T cells. Within the nucleus, PKC-θ catalytic activity maintains the Ser536 phosphorylation on the p65 subunit of NF-κB (also known as RelA) and can directly influence chromatin accessibility at transcriptional memory genes by regulating H2B deposition through Ser32 phosphorylation. Furthermore, using a cytoplasm-restricted PKC-θ mutant, we highlight that chromatin-anchored PKC-θ integrates activating signals at the chromatin template to elicit transcriptional memory responses in human memory T cells.
Subject(s)
CD4-Positive T-Lymphocytes/metabolism , Cell Nucleus/enzymology , Histones/metabolism , Immunologic Memory/genetics , Isoenzymes/metabolism , Protein Kinase C/metabolism , Transcription Factor RelA/metabolism , Transcription, Genetic , Amino Acid Sequence , Chromatin/metabolism , Gene Expression Regulation , Histones/chemistry , Humans , Jurkat Cells , Phosphorylation , Phosphoserine/metabolism , Protein Kinase C-theta , Signal TransductionABSTRACT
Cisplatin is an effective anticancer drug; however, cisplatin use often leads to nephrotoxicity, which limits its clinical effectiveness. In this study, we determined the effect of dichloroacetate, a novel anticancer agent, in a mouse model of cisplatin-induced AKI. Pretreatment with dichloroacetate significantly attenuated the cisplatin-induced increase in BUN and serum creatinine levels, renal tubular apoptosis, and oxidative stress. Additionally, pretreatment with dichloroacetate accelerated tubular regeneration after cisplatin-induced renal damage. Whole transcriptome sequencing revealed that dichloroacetate prevented mitochondrial dysfunction and preserved the energy-generating capacity of the kidneys by preventing the cisplatin-induced downregulation of fatty acid and glucose oxidation, and of genes involved in the Krebs cycle and oxidative phosphorylation. Notably, dichloroacetate did not interfere with the anticancer activity of cisplatin in vivo. These data provide strong evidence that dichloroacetate preserves renal function when used in conjunction with cisplatin.
Subject(s)
Antineoplastic Agents/adverse effects , Cisplatin/adverse effects , Dichloroacetic Acid/therapeutic use , Kidney Diseases/chemically induced , Kidney Diseases/prevention & control , Animals , Antineoplastic Agents/therapeutic use , Cisplatin/therapeutic use , Female , Male , Mice , Mice, Inbred BALB CABSTRACT
Interleukins are a group of cytokines with complex immunomodulatory functions that are important for regulating immunity in vertebrate species. Reptiles and mammals last shared a common ancestor more than 350 million years ago, so it is not surprising that low sequence identity has prevented divergent interleukin genes from being identified in the central bearded dragon lizard, Pogona vitticeps, in its genome assembly. To determine the complete nucleotide sequences of key interleukin genes, we constructed full-length transcripts, using the Trinity platform, from short paired-end read RNA sequences from stimulated spleen cells. De novo transcript reconstruction and analysis allowed us to identify interleukin genes that are missing from the published P. vitticeps assembly. Identification of key cytokines in P. vitticeps will provide insight into the essential molecular mechanisms and evolution of interleukin gene families and allow for characterization of the immune response in a lizard for comparison with mammals.
Subject(s)
Computational Biology/methods , High-Throughput Nucleotide Sequencing/methods , Interleukins/genetics , Lizards/genetics , Sequence Analysis, RNA/methods , Transcriptome/genetics , Amino Acid Sequence , Animals , Gene Expression Profiling , Sequence Homology, Amino Acid , SoftwareABSTRACT
BACKGROUND: Immunological memory is the ability of the immune system to respond more rapidly and effectively to previously encountered pathogens, a key feature of adaptive immunity. The capacity of memory T cells to "remember" previous cellular responses to specific antigens ultimately resides in their unique patterns of gene expression. Following re-exposure to an antigen, previously activated genes are transcribed more rapidly and robustly in memory T cells compared to their naïve counterparts. The ability for cells to remember past transcriptional responses is termed "adaptive transcriptional memory". RESULTS: Recent global epigenome studies suggest that epigenetic mechanisms are central to establishing and maintaining transcriptional memory, with elegant studies in model organisms providing tantalizing insights into the epigenetic programs that contribute to adaptive immunity. These epigenetic mechanisms are diverse, and include not only classical acetylation and methylation events, but also exciting and less well-known mechanisms involving histone structure, upstream signalling pathways, and nuclear localisation of genomic regions. CONCLUSIONS: Current global health challenges in areas such as tuberculosis and influenza demand not only more effective and safer vaccines, but also vaccines for a wider range of health priorities, including HIV, cancer, and emerging pathogens such as Ebola. Understanding the multi-layered epigenetic mechanisms that underpin the rapid recall responses of memory T cells following reactivation is a critical component of this development pathway.
Subject(s)
Epigenesis, Genetic , Immunologic Memory/genetics , T-Lymphocytes/metabolism , Transcription, Genetic , Animals , Chromatin/metabolism , Histones/metabolism , HumansABSTRACT
Experimental autoimmune encephalomyelitis (EAE) is a T cell-mediated autoimmune disease involving effector Th subsets such as Th1 and Th17. In this study, we demonstrate that mice lacking the NF-κB transcription factor family member c-Rel (rel(-/-)), which are known to be resistant to EAE, show impaired Th17 development. Mixed bone marrow chimeras and EAE adoptive transfer experiments show that the deficiency of effector Th17 cells in rel(-/-) mice is T cell intrinsic. Consistent with this finding, c-Rel was activated in response to TCR signaling in the early stages of Th17 development and controlled the expression of Rorc, which encodes the Th17 transcription factor retinoic acid-related orphan receptor γt. CD28, but not IL-2, repression of Th17 development was dependent on c-Rel, implicating a dual role for c-Rel in modulating Th17 development. Adoptive transfer experiments also suggested that c-Rel control of regulatory T cell differentiation and homeostasis influences EAE development and severity by influencing the balance between Th17 and regulatory T cells. Collectively, our findings indicate that in addition to promoting Th1 differentiation, c-Rel regulates the development and severity of EAE via multiple mechanisms that impact on the generation of Th17 cells.
Subject(s)
Cell Differentiation/immunology , Encephalomyelitis, Autoimmune, Experimental/immunology , Proto-Oncogene Proteins c-rel/physiology , Th17 Cells/cytology , Th17 Cells/immunology , Amino Acid Sequence , Animals , CD28 Antigens/physiology , Cell Differentiation/genetics , Cells, Cultured , Disease Resistance/genetics , Disease Resistance/immunology , Encephalomyelitis, Autoimmune, Experimental/genetics , Encephalomyelitis, Autoimmune, Experimental/pathology , Female , Growth Inhibitors/deficiency , Growth Inhibitors/genetics , Growth Inhibitors/physiology , Mice , Mice, Inbred C57BL , Mice, Knockout , Molecular Sequence Data , Proto-Oncogene Proteins c-rel/deficiency , Proto-Oncogene Proteins c-rel/genetics , Severity of Illness Index , Th17 Cells/pathologyABSTRACT
IL-21 is a member of the common gamma-chain-dependent cytokine family and is a key modulator of lymphocyte development, proliferation, and differentiation. IL-21 is highly expressed in activated CD4(+) T cells and plays a critical role in the expansion and differentiation of the Th cell subsets, Th17 and follicular helper T (T(FH)) cells. Because of its potent activity in both myeloid and lymphoid cell immune responses, it has been implicated in a number of autoimmune diseases and has also been used as a therapeutic agent in the treatment of some cancers. In this study, we demonstrate that c-Rel, a member of the NF-kappaB family of transcription factors, is required for IL-21 gene expression in T lymphocytes. IL-21 mRNA and protein levels are reduced in the CD4(+) cells of rel(-/-) mice when compared with rel(+/+) mice in both in vitro and in vivo models. A c-Rel binding site identified in the proximal promoter of il21 is confirmed to bind c-Rel in vitro and in vivo and to regulate expression from the il21 promoter in T cells. Downstream of IL-21 expression, Th17, T(FH), and germinal center B cell development are also impaired in rel(-/-) mice. The administration of IL-21 protein rescued the development of T(FH) cells but not germinal center B cells. Taken together, c-Rel plays an important role in the expression of IL-21 in T cells and subsequently in IL-21-dependent T(FH) cell development.
Subject(s)
Gene Expression Regulation , Interleukins/genetics , Proto-Oncogene Proteins c-rel/metabolism , T-Lymphocytes/metabolism , Amino Acid Sequence , Animals , Binding Sites/genetics , Cell Line, Tumor , Encephalomyelitis, Autoimmune, Experimental/genetics , Encephalomyelitis, Autoimmune, Experimental/metabolism , Encephalomyelitis, Autoimmune, Experimental/prevention & control , Enzyme-Linked Immunosorbent Assay , Female , Flow Cytometry , Gene Expression Profiling , Interleukin-17/metabolism , Interleukins/metabolism , Interleukins/pharmacology , Lymphocyte Activation , Male , Mice , Mice, Inbred C57BL , Mice, Knockout , NF-kappa B/genetics , NF-kappa B/metabolism , Promoter Regions, Genetic/genetics , Protein Binding , Proto-Oncogene Proteins c-rel/genetics , Reverse Transcriptase Polymerase Chain Reaction , T-Lymphocytes, Helper-Inducer/metabolismABSTRACT
Protein kinase C (PKC)-θ is a serine/threonine kinase with both cytoplasmic and nuclear functions. Nuclear chromatin-associated PKC-θ (nPKC-θ) is increasingly recognized to be pathogenic in cancer, whereas its cytoplasmic signaling is restricted to normal T-cell function. Here we show that nPKC-θ is enriched in circulating tumor cells (CTCs) in patients with triple-negative breast cancer (TNBC) brain metastases and immunotherapy-resistant metastatic melanoma and is associated with poor survival in immunotherapy-resistant disease. To target nPKC-θ, we designed a novel PKC-θ peptide inhibitor (nPKC-θi2) that selectively inhibits nPKC-θ nuclear translocation but not PKC-θ signaling in healthy T cells. Targeting nPKC-θ reduced mesenchymal cancer stem cell signatures in immunotherapy-resistant CTCs and TNBC xenografts. PKC-θ was also enriched in the nuclei of CD8+ T cells isolated from stage IV immunotherapy-resistant metastatic cancer patients. We show for the first time that nPKC-θ complexes with ZEB1, a key repressive transcription factor in epithelial-to-mesenchymal transition (EMT), in immunotherapy-resistant dysfunctional PD1+/CD8+ T cells. nPKC-θi2 inhibited the ZEB1/PKC-θ repressive complex to induce cytokine production in CD8+ T cells isolated from patients with immunotherapy-resistant disease. These data establish for the first time that nPKC-θ mediates immunotherapy resistance via its activity in CTCs and dysfunctional CD8+ T cells. Disrupting nPKC-θ but retaining its cytoplasmic function may offer a means to target metastases in combination with chemotherapy or immunotherapy.
ABSTRACT
Naive CD8+ T cell activation results in an autonomous program of cellular proliferation and differentiation. However, the mechanisms that underpin this process are unclear. Here, we profile genome-wide changes in chromatin accessibility, gene transcription, and the deposition of a key chromatin modification (H3K27me3) early after naive CD8+ T cell activation. Rapid upregulation of the histone demethylase KDM6B prior to the first cell division is required for initiating H3K27me3 removal at genes essential for subsequent T cell differentiation and proliferation. Inhibition of KDM6B-dependent H3K27me3 demethylation limits the magnitude of an effective primary virus-specific CD8+ T cell response and the formation of memory CD8+ T cell populations. Accordingly, we define the early spatiotemporal events underpinning early lineage-specific chromatin reprogramming that are necessary for autonomous CD8+ T cell proliferation and differentiation.
Subject(s)
CD8-Positive T-Lymphocytes/immunology , Cell Differentiation/immunology , Chromatin Assembly and Disassembly , Jumonji Domain-Containing Histone Demethylases/metabolism , Viruses/immunology , Animals , Demethylation , Female , Histones/metabolism , Humans , Immunologic Memory , Lymphocyte Activation , Lysine/metabolism , Male , Mice, Inbred C57BL , Protein Binding , Transcription Factors/metabolism , Up-RegulationABSTRACT
Lysine specific demethylase 1 (LSD1) is a key epigenetic eraser enzyme implicated in cancer metastases and recurrence. Nuclear LSD1 phosphorylated at serine 111 (nLSD1p) has been shown to be critical for the development of breast cancer stem cells. Here we show that circulating tumor cells isolated from immunotherapy-resistant metastatic melanoma patients express higher levels of nLSD1p compared to responders, which is associated with co-expression of stem-like, mesenchymal genes. Targeting nLSD1p with selective nLSD1 inhibitors better inhibits the stem-like mesenchymal signature than traditional FAD-specific LSD1 catalytic inhibitors such as GSK2879552. We also demonstrate that nLSD1p is enriched in PD-1+CD8+ T cells from resistant melanoma patients and 4T1 immunotherapy-resistant mice. Targeting the LSD1p nuclear axis induces IFN-γ/TNF-α-expressing CD8+ T cell infiltration into the tumors of 4T1 immunotherapy-resistant mice, which is further augmented by combined immunotherapy. Underpinning these observations, nLSD1p is regulated by the key T cell exhaustion transcription factor EOMES in dysfunctional CD8+ T cells. EOMES co-exists with nLSD1p in PD-1+CD8+ T cells in resistant patients, and nLSD1p regulates EOMES nuclear dynamics via demethylation/acetylation switching of critical EOMES residues. Using novel antibodies to target these post-translational modifications, we show that EOMES demethylation/acetylation is reciprocally expressed in resistant and responder patients. Overall, we show for the first time that dual inhibition of metastatic cancer cells and re-invigoration of the immune system requires LSD1 inhibitors that target the nLSD1p axis.
Subject(s)
Cellular Reprogramming/drug effects , Cellular Reprogramming/genetics , Histone Demethylases/genetics , Neoplasms/etiology , T-Box Domain Proteins/metabolism , T-Lymphocytes/drug effects , T-Lymphocytes/metabolism , Animals , Biomarkers , CD8-Positive T-Lymphocytes/immunology , CD8-Positive T-Lymphocytes/metabolism , Cell Line, Tumor , Cell Nucleus/genetics , Cell Nucleus/metabolism , Female , Flow Cytometry , Fluorescent Antibody Technique , Gene Expression , Gene Expression Profiling , High-Throughput Nucleotide Sequencing , Histone Demethylases/metabolism , Humans , Immunotherapy , Mice , Neoplasms/metabolism , Neoplasms/pathology , Neoplasms/therapy , T-Box Domain Proteins/genetics , T-Lymphocytes/immunology , Treatment OutcomeABSTRACT
Our knowledge of regulatory mechanisms of gene expression and other chromosomal processes related to DNA methylation and chromatin state is continuing to grow at a rapid pace. Understanding how these epigenomic phenomena vary between individuals will have an impact on understanding their broader role in determining variation in gene expression and biochemical, physiological, and behavioural phenotypes. In this review we survey recent progress in this area, focusing on data available from humans. We highlight the role of obligatory (sequence-dependent) epigenomic variation as an important mechanism for generating interindividual variation that could impact our understanding of the mechanistic basis of complex trait architecture.
Subject(s)
Epigenesis, Genetic , Genetic Variation , DNA Methylation , Genome, Human , HumansABSTRACT
Macrophages play an important role in regulating the tumor microenvironment (TME). Here we show that classical (M1) macrophage polarization reduced expression of LSD1, nuclear REST corepressor 1 (CoREST), and the zinc finger protein SNAIL. The LSD1 inhibitor phenelzine targeted both the flavin adenine dinucleotide (FAD) and CoREST binding domains of LSD1, unlike the LSD1 inhibitor GSK2879552, which only targeted the FAD domain. Phenelzine treatment reduced nuclear demethylase activity and increased transcription and expression of M1-like signatures both in vitro and in a murine triple-negative breast cancer model. Overall, the LSD1 inhibitors phenelzine and GSK2879552 are useful tools for dissecting the contribution of LSD1 demethylase activity and the nuclear LSD1-CoREST complex to switching macrophage polarization programs. These findings suggest that inhibitors must have dual FAD and CoREST targeting abilities to successfully initiate or prime macrophages toward an anti-tumor M1-like phenotype in triple-negative breast cancer.
Subject(s)
Histone Demethylases/metabolism , Macrophages/immunology , Triple Negative Breast Neoplasms/metabolism , Animals , Cell Differentiation , Co-Repressor Proteins/metabolism , Cytokines/metabolism , Disease Models, Animal , Flavin-Adenine Dinucleotide/metabolism , Histone Demethylases/antagonists & inhibitors , Histone Demethylases/genetics , Humans , Macrophage Activation , Mice , Nerve Tissue Proteins/metabolism , Phenelzine/pharmacology , RAW 264.7 Cells , RNA, Small Interfering/genetics , Snail Family Transcription Factors/metabolism , Th1 Cells/immunology , Triple Negative Breast Neoplasms/immunology , Tumor MicroenvironmentABSTRACT
Immune reconstitution following hematopoietic stem cell transplantation (HSCT) is critical in preventing harmful sequelae in recipients with cytomegalovirus (CMV) infection. To understand the molecular mechanisms underlying immune reconstitution kinetics, we profiled the transcriptome-chromatin accessibility landscape of CMV-specific CD8+ T cells from HCST recipients with different immune reconstitution efficiencies. CMV-specific T cells from HSCT recipients with stable antiviral immunity expressed higher levels of interferon/defense response and cell cycle genes in an interconnected network involving PI3KCG, STAT5B, NFAT, RBPJ, and lower HDAC6, increasing chromatin accessibility at the enhancer regions of immune and T-cell receptor signaling pathway genes. By contrast, the transcriptional and epigenomic signatures of CMV-specific T cells from HSCT recipients with unstable immune reconstitution showed commonalities with T-cell responses in other nonresolving chronic infections. These signatures included higher levels of EGR and KLF factors that, along with lower JARID2 expression, maintained higher accessibility at promoter and CpG-rich regions of genes associated with apoptosis. Furthermore, epigenetic targeting via inhibition of HDAC6 or JARID2 enhanced the transcription of genes associated with differential responses, suggesting that drugs targeting epigenomic modifiers may have therapeutic potential for enhancing immune reconstitution in HSCT recipients. Taken together, these analyses demonstrate that transcription factors and chromatin modulators create different chromatin accessibility landscapes in T cells of HSCT recipients that not only affect immediate gene expression but also differentially prime cells for responses to additional signals. Epigenetic therapy may be a promising strategy to promote immune reconstitution in HSCT recipients.
Subject(s)
Cellular Reprogramming/genetics , Cellular Reprogramming/immunology , Epigenesis, Genetic , Immune Reconstitution , T-Lymphocytes/immunology , T-Lymphocytes/metabolism , Chromatin Assembly and Disassembly , Cytomegalovirus/immunology , Cytomegalovirus Infections/etiology , Gene Expression Regulation , Hematopoietic Stem Cell Transplantation , Hematopoietic Stem Cells/cytology , Hematopoietic Stem Cells/metabolism , Humans , T-Cell Antigen Receptor Specificity , Transcription Factors/metabolism , Transcriptome , Transplant Recipients , Virus ReplicationABSTRACT
Memory T cells exhibit transcriptional memory and "remember" their previous pathogenic encounter to increase transcription on re-infection. However, how this transcriptional priming response is regulated is unknown. Here we performed global FAIRE-seq profiling of chromatin accessibility in a human T cell transcriptional memory model. Primary activation induced persistent accessibility changes, and secondary activation induced secondary-specific opening of previously less accessible regions associated with enhanced expression of memory-responsive genes. Increased accessibility occurred largely in distal regulatory regions and was associated with increased histone acetylation and relative H3.3 deposition. The enhanced re-stimulation response was linked to the strength of initial PKC-induced signalling, and PKC-sensitive increases in accessibility upon initial stimulation showed higher accessibility on re-stimulation. While accessibility maintenance was associated with ETS-1, accessibility at re-stimulation-specific regions was linked to NFAT, especially in combination with ETS-1, EGR, GATA, NFκB, and NR4A. Furthermore, NFATC1 was directly regulated by ETS-1 at an enhancer region. In contrast to the factors that increased accessibility, signalling from bHLH and ZEB family members enhanced decreased accessibility upon re-stimulation. Interplay between distal regulatory elements, accessibility, and the combined action of sequence-specific transcription factors allows transcriptional memory-responsive genes to "remember" their initial environmental encounter.
Subject(s)
Chromatin Assembly and Disassembly , Chromatin/genetics , Immunologic Memory/genetics , T-Lymphocytes/immunology , T-Lymphocytes/metabolism , Transcription, Genetic , Acetylation , Binding Sites , CD4-Positive T-Lymphocytes/immunology , CD4-Positive T-Lymphocytes/metabolism , GATA Transcription Factors/metabolism , Gene Expression Profiling , Histones/metabolism , Humans , Lymphocyte Activation/genetics , Lymphocyte Activation/immunology , NFATC Transcription Factors/metabolism , Promoter Regions, Genetic , Protein BindingABSTRACT
T cell activation involves the recognition of a foreign antigen complexed to the major histocompatibility complex on the antigen presenting T cell to the T cell receptor. This leads to activation of signaling pathways, which ultimately leads to induction of key cytokine genes responsible for eradication of foreign antigens. We used the mouse EL4 T cell as a model system to study genes that are induced as a result of T cell activation using phorbol myristate acetate (PMA) and calcium ionomycin (I) as stimuli. We were also interested to examine the importance of new protein synthesis in regulating the expression of genes involved in T cell activation. Thus we have pre-treated mouse EL4 T cells with cycloheximide, a protein synthesis inhibitor, and left the cells unstimulated or stimulated with PMA/I for 4 h. We performed microarray expression profiling of these cells to correlate the gene expression with chromatin state of T cells upon T cell activation [1]. Here, we detail further information and analysis of the microarray data, which shows that T cell activation leads to differential expression of genes and inducible genes can be further classified as primary and secondary response genes based on their protein synthesis dependency. The data is available in the Gene Expression Omnibus under accession number GSE13278.
ABSTRACT
Dual-specificity phosphatases (DUSPs) dephosphorylate threonine/serine and tyrosine residues on their substrates. Here we show that DUSP1, DUSP4, and DUSP6 are involved in epithelial-to-mesenchymal transition (EMT) and breast cancer stem cell (CSC) regulation. DUSP1, DUSP4, and DUSP6 are induced during EMT in a PKC pathway signal-mediated EMT model. We show for the first time that the key chromatin-associated kinase PKC-θ directly regulates a subset of DUSP family members. DUSP1, DUSP4, and DUSP6 globally but differentially co-exist with enhancer and permissive active histone post-translational modifications, suggesting that they play distinct roles in gene regulation in EMT/CSCs. We show that nuclear DUSP4 associates with the key acetyltransferase p300 in the context of the chromatin template and dynamically regulates the interplay between two key phosphorylation marks: the 1834 (active) and 89 (inhibitory) residues central to p300's acetyltransferase activity. Furthermore, knockdown with small-interfering RNAs (siRNAs) shows that DUSP4 is required for maintaining H3K27ac, a mark mediated by p300. DUSP1, DUSP4, and DUSP6 knockdown with siRNAs shows that they participate in the formation of CD44hi/CD24lo/EpCAM+ breast CSCs: DUSP1 knockdown reduces CSC formation, while DUSP4 and DUSP6 knockdown enhance CSC formation. Moreover, DUSP6 is overexpressed in patient-derived HER2+ breast carcinomas compared to benign mammary tissue. Taken together, these findings illustrate novel pleiotropic roles for DUSP family members in EMT and CSC regulation in breast cancer.
Subject(s)
Breast Neoplasms/pathology , Dual-Specificity Phosphatases/metabolism , Epithelial-Mesenchymal Transition , Neoplastic Stem Cells/pathology , Biomarkers, Tumor/deficiency , Biomarkers, Tumor/genetics , Biomarkers, Tumor/metabolism , Chromatin/metabolism , Dual-Specificity Phosphatases/deficiency , Dual-Specificity Phosphatases/genetics , E1A-Associated p300 Protein/metabolism , Epigenomics , Gene Knockdown Techniques , Genetic Loci/genetics , Histones/chemistry , Histones/metabolism , Humans , Lysine/metabolism , MCF-7 Cells , Phosphorylation , Protein Kinase C/metabolism , Protein Processing, Post-Translational , Protein TransportABSTRACT
The effects of the antioxidant alpha-lipoic acid (LA) on the proliferation of mitogen-stimulated human peripheral blood lymphocytes (HPBL) were investigated in comparison to its effects on the proliferation of two leukaemic T cell lines, Jurkat and CCRF-CEM. At low mM concentrations, LA inhibited in a dose-dependent manner DNA synthesis of HPBL stimulated with either phorbol myristate acetate (PMA) in combination with ionomycin (IoM), or phytohaemagglutinin (PHA). At similar concentrations, LA inhibited the proliferation of Jurkat and CCRF-CEM cells. However, LA was preferentially cytotoxic to the leukaemic cell lines. The selective toxicity of LA to Jurkat cells was shown by electron microscopy (EM) to be due to the induction of apoptosis. Furthermore, LA had different effects on the secretion of interleukin-2 (IL-2) and steady-state levels of IL-2 mRNA in mitogen-stimulated HPBL depending on the mitogens used. LA dramatically increased the induction of IL-2 mRNA and IL-2 protein secretion in PMA/IoM-stimulated HPBL, whereas it inhibited these in HPBL stimulated with PHA. The differential effects of LA on normal and leukaemic T lymphocytes may indicate a new route towards development of therapeutic agents.
Subject(s)
Antioxidants/pharmacology , Leukemia, T-Cell/metabolism , Lymphocyte Activation/drug effects , T-Lymphocytes/metabolism , Thioctic Acid/pharmacology , Cell Survival/drug effects , Dose-Response Relationship, Drug , Humans , Ionomycin/pharmacology , Ionophores/pharmacology , Jurkat Cells , Leukemia, T-Cell/pathology , Mitogens/pharmacology , Oxidation-Reduction , Phytohemagglutinins/pharmacology , T-Lymphocytes/pathology , Tetradecanoylphorbol Acetate/pharmacologyABSTRACT
The protein kinase C (PKC) activator phorbol 12-myristate 13-acetate (PMA) induces transition of the epithelial MCF-7 cell line to a mesenchymal phenotype. A subset of the resulting mesenchymal cells has surface markers characteristics of a cancer stem cell (CSC) population. We profiled the transcriptome changes associated with the epithelial to mesenchymal transition and those that occurred in the CSC subset. Using a siRNA knockdown strategy, we examined the extent to which these changes were dependent on the PKC family member, PKC-θ. The importance of the cytoplasmic signaling role of this kinase is well established and in this study, we have shown by PKC-θ ChIP-sequencing analysis that this kinase has a dual role with the ability to also associate with chromatin on a subset of PKC-θ dependent genes. In the associated manuscript (Zafar et al., 2014 [5]) we presented evidence for the first time showing that this nuclear role of PKC-θ is also important for gene induction and mesenchymal/CSC phenotype. Here we describe the analysis associated with the transcriptome and ChIP-seq data presented in Zafar et al. (2014) [5] and uploaded to NCBI Gene Expression Omnibus (GSE53335).