1
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Wolf S, Melo D, Garske KM, Pallares LF, Lea AJ, Ayroles JF. Characterizing the landscape of gene expression variance in humans. PLoS Genet 2023; 19:e1010833. [PMID: 37410774 DOI: 10.1371/journal.pgen.1010833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 06/15/2023] [Indexed: 07/08/2023] Open
Abstract
Gene expression variance has been linked to organismal function and fitness but remains a commonly neglected aspect of molecular research. As a result, we lack a comprehensive understanding of the patterns of transcriptional variance across genes, and how this variance is linked to context-specific gene regulation and gene function. Here, we use 57 large publicly available RNA-seq data sets to investigate the landscape of gene expression variance. These studies cover a wide range of tissues and allowed us to assess if there are consistently more or less variable genes across tissues and data sets and what mechanisms drive these patterns. We show that gene expression variance is broadly similar across tissues and studies, indicating that the pattern of transcriptional variance is consistent. We use this similarity to create both global and within-tissue rankings of variation, which we use to show that function, sequence variation, and gene regulatory signatures contribute to gene expression variance. Low-variance genes are associated with fundamental cell processes and have lower levels of genetic polymorphisms, have higher gene-gene connectivity, and tend to be associated with chromatin states associated with transcription. In contrast, high-variance genes are enriched for genes involved in immune response, environmentally responsive genes, immediate early genes, and are associated with higher levels of polymorphisms. These results show that the pattern of transcriptional variance is not noise. Instead, it is a consistent gene trait that seems to be functionally constrained in human populations. Furthermore, this commonly neglected aspect of molecular phenotypic variation harbors important information to understand complex traits and disease.
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Affiliation(s)
- Scott Wolf
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, United States of America
| | - Diogo Melo
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, United States of America
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, United States of America
| | - Kristina M Garske
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, United States of America
| | - Luisa F Pallares
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, United States of America
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, United States of America
- Friedrich Miescher Laboratory of the Max Planck Society, Tübingen, Germany
| | - Amanda J Lea
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
- Child and Brain Development, Canadian Institute for Advanced Research, Toronto, Canada
| | - Julien F Ayroles
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, United States of America
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, United States of America
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2
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A transcriptional cycling model recapitulates chromatin-dependent features of noisy inducible transcription. PLoS Comput Biol 2022; 18:e1010152. [PMID: 36084132 PMCID: PMC9491597 DOI: 10.1371/journal.pcbi.1010152] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 09/21/2022] [Accepted: 08/12/2022] [Indexed: 11/23/2022] Open
Abstract
Activation of gene expression in response to environmental cues results in substantial phenotypic heterogeneity between cells that can impact a wide range of outcomes including differentiation, viral activation, and drug resistance. An important source of gene expression noise is transcriptional bursting, or the process by which transcripts are produced during infrequent bursts of promoter activity. Chromatin accessibility impacts transcriptional bursting by regulating the assembly of transcription factor and polymerase complexes on promoters, suggesting that the effect of an activating signal on transcriptional noise will depend on the initial chromatin state at the promoter. To explore this possibility, we simulated transcriptional activation using a transcriptional cycling model with three promoter states that represent chromatin remodeling, polymerase binding and pause release. We initiated this model over a large parameter range representing target genes with different chromatin environments, and found that, upon increasing the polymerase pause release rate to activate transcription, changes in gene expression noise varied significantly across initial promoter states. This model captured phenotypic differences in activation of latent HIV viruses integrated at different chromatin locations and mediated by the transcription factor NF-κB. Activating transcription in the model via increasing one or more of the transcript production rates, as occurs following NF-κB activation, reproduced experimentally measured transcript distributions for four different latent HIV viruses, as well as the bimodal pattern of HIV protein expression that leads to a subset of reactivated virus. Importantly, the parameter ‘activation path’ differentially affected gene expression noise, and ultimately viral activation, in line with experimental observations. This work demonstrates how upstream signaling pathways can be connected to biological processes that underlie transcriptional bursting, resulting in target gene-specific noise profiles following stimulation of a single upstream pathway. Many genes are transcribed in infrequent bursts of mRNA production through a process called transcriptional bursting, which contributes to variability in responses between cells. Heterogeneity in cell responses can have important biological impacts, such as whether a cell supports viral replication or responds to a drug, and thus there is an effort to describe this process with mathematical models to predict biological outcomes. Previous models described bursting as a transition between an “OFF” state or an “ON” state, an elegant and simple mathematical representation of complex molecular mechanisms, but one which failed to capture how upstream activation signals affected bursting. To address this, we added an additional promoter state to better reflect biological mechanisms underlying bursting. By fitting this model to variable activation of quiescent HIV infections in T cells, we showed that our model more accurately described viral expression variability across cells in response to an upstream stimulus. Our work highlights how mathematical models can be further developed to understand complex biological mechanisms and suggests ways to connect transcriptional bursting to upstream activation pathways.
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3
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Post-Transcriptional Control of mRNA Metabolism and Protein Secretion: The Third Level of Regulation within the NF-κB System. Biomedicines 2022; 10:biomedicines10092108. [PMID: 36140209 PMCID: PMC9495616 DOI: 10.3390/biomedicines10092108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 08/12/2022] [Accepted: 08/21/2022] [Indexed: 11/17/2022] Open
Abstract
The NF-κB system is a key transcriptional pathway that regulates innate and adaptive immunity because it triggers the activation and differentiation processes of lymphocytes and myeloid cells during immune responses. In most instances, binding to cytoplasmic inhibitory IκB proteins sequesters NF-κB into an inactive state, while a plethora of external triggers activate three complex signaling cascades that mediate the release and nuclear translocation of the NF-κB DNA-binding subunits. In addition to these cytosolic steps (level 1 of NF-κB regulation), NF-κB activity is also controlled in the nucleus by signaling events, cofactors and the chromatin environment to precisely determine chromatin recruitment and the specificity and timing of target gene transcription (level 2 of NF-κB regulation). Here, we discuss an additional layer of the NF-κB system that manifests in various steps of post-transcriptional gene expression and protein secretion. This less-studied regulatory level allows reduction of (transcriptional) noise and signal integration and endows time-shifted control of the secretion of inflammatory mediators. Detailed knowledge of these steps is important, as dysregulated post-transcriptional NF-κB signaling circuits are likely to foster chronic inflammation and contribute to the formation and maintenance of a tumor-promoting microenvironment.
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4
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Epithelial NELF guards intestinal barrier function to ameliorate colitis by maintaining junctional integrity. Mucosal Immunol 2022; 15:279-288. [PMID: 34697434 PMCID: PMC8881342 DOI: 10.1038/s41385-021-00465-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2021] [Revised: 09/27/2021] [Accepted: 10/09/2021] [Indexed: 02/04/2023]
Abstract
Well-orchestrated transcriptional programs in intestinal epithelial cells (IECs) are essential for maintenance of optimal mucosal barrier functions, whereas the contribution of elongation-related mechanisms to barrier function remains unknown. Here, a combination of genetic and genomic approaches defined a critical role of IEC-intrinsic negative elongation factor (NELF) complex in maintenance of epithelial homeostasis. By direct occupancy at endogenous gene loci, NELF sustained expression of a subset of genes related to junctional integrity. As a result, epithelial NELF deficiency results in subdued levels of these junction-related genes and excessive IEC necroptosis in vivo secondary to commensal microbial invasion. In a colitis model, NELF-deficient mice exhibited severely impaired barrier integrity characterized by increased intestinal permeability and significantly exacerbated intestinal inflammation with lethal consequences. Our findings reveal the protective function of the NELF complex against intestinal damage and inflammation and suggest that elongation represents a biologically important step in defining IEC transcriptome.
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5
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Meier-Soelch J, Mayr-Buro C, Juli J, Leib L, Linne U, Dreute J, Papantonis A, Schmitz ML, Kracht M. Monitoring the Levels of Cellular NF-κB Activation States. Cancers (Basel) 2021; 13:5351. [PMID: 34771516 PMCID: PMC8582385 DOI: 10.3390/cancers13215351] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Accepted: 10/18/2021] [Indexed: 12/12/2022] Open
Abstract
The NF-κB signaling system plays an important regulatory role in the control of many biological processes. The activities of NF-κB signaling networks and the expression of their target genes are frequently elevated in pathophysiological situations including inflammation, infection, and cancer. In these conditions, the outcome of NF-κB activity can vary according to (i) differential activation states, (ii) the pattern of genomic recruitment of the NF-κB subunits, and (iii) cellular heterogeneity. Additionally, the cytosolic NF-κB activation steps leading to the liberation of DNA-binding dimers need to be distinguished from the less understood nuclear pathways that are ultimately responsible for NF-κB target gene specificity. This raises the need to more precisely determine the NF-κB activation status not only for the purpose of basic research, but also in (future) clinical applications. Here we review a compendium of different methods that have been developed to assess the NF-κB activation status in vitro and in vivo. We also discuss recent advances that allow the assessment of several NF-κB features simultaneously at the single cell level.
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Affiliation(s)
- Johanna Meier-Soelch
- Rudolf Buchheim Institute of Pharmacology, Justus Liebig University, 35392 Giessen, Germany; (J.M.-S.); (C.M.-B.); (J.J.); (L.L.)
| | - Christin Mayr-Buro
- Rudolf Buchheim Institute of Pharmacology, Justus Liebig University, 35392 Giessen, Germany; (J.M.-S.); (C.M.-B.); (J.J.); (L.L.)
| | - Jana Juli
- Rudolf Buchheim Institute of Pharmacology, Justus Liebig University, 35392 Giessen, Germany; (J.M.-S.); (C.M.-B.); (J.J.); (L.L.)
| | - Lisa Leib
- Rudolf Buchheim Institute of Pharmacology, Justus Liebig University, 35392 Giessen, Germany; (J.M.-S.); (C.M.-B.); (J.J.); (L.L.)
| | - Uwe Linne
- Mass Spectrometry Facility of the Department of Chemistry, Philipps University, 35032 Marburg, Germany;
| | - Jan Dreute
- Institute of Biochemistry, Justus Liebig University, 35392 Giessen, Germany;
| | - Argyris Papantonis
- Institute of Pathology, University Medical Center Göttingen, 37075 Göttingen, Germany;
| | - M. Lienhard Schmitz
- Institute of Biochemistry, Justus Liebig University, 35392 Giessen, Germany;
| | - Michael Kracht
- Rudolf Buchheim Institute of Pharmacology, Justus Liebig University, 35392 Giessen, Germany; (J.M.-S.); (C.M.-B.); (J.J.); (L.L.)
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6
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Devenish LP, Mhlanga MM, Negishi Y. Immune Regulation in Time and Space: The Role of Local- and Long-Range Genomic Interactions in Regulating Immune Responses. Front Immunol 2021; 12:662565. [PMID: 34046034 PMCID: PMC8144502 DOI: 10.3389/fimmu.2021.662565] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 04/26/2021] [Indexed: 12/27/2022] Open
Abstract
Mammals face and overcome an onslaught of endogenous and exogenous challenges in order to survive. Typical immune cells and barrier cells, such as epithelia, must respond rapidly and effectively to encountered pathogens and aberrant cells to prevent invasion and eliminate pathogenic species before they become overgrown and cause harm. On the other hand, inappropriate initiation and failed termination of immune cell effector function in the absence of pathogens or aberrant tissue gives rise to a number of chronic, auto-immune, and neoplastic diseases. Therefore, the fine control of immune effector functions to provide for a rapid, robust response to challenge is essential. Importantly, immune cells are heterogeneous due to various factors relating to cytokine exposure and cell-cell interaction. For instance, tissue-resident macrophages and T cells are phenotypically, transcriptionally, and functionally distinct from their circulating counterparts. Indeed, even the same cell types in the same environment show distinct transcription patterns at the single cell level due to cellular noise, despite being robust in concert. Additionally, immune cells must remain quiescent in a naive state to avoid autoimmunity or chronic inflammatory states but must respond robustly upon activation regardless of their microenvironment or cellular noise. In recent years, accruing evidence from next-generation sequencing, chromatin capture techniques, and high-resolution imaging has shown that local- and long-range genome architecture plays an important role in coordinating rapid and robust transcriptional responses. Here, we discuss the local- and long-range genome architecture of immune cells and the resultant changes upon pathogen or antigen exposure. Furthermore, we argue that genome structures contribute functionally to rapid and robust responses under noisy and distinct cellular environments and propose a model to explain this phenomenon.
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Affiliation(s)
- Liam P Devenish
- Division of Chemical, Systems, and Synthetic Biology, Department of Integrative Biomedical Sciences, Institute of Infectious Disease & Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Musa M Mhlanga
- Radboud Institute for Molecular Life Sciences (RIMLS), Radboud University Medical Center, Nijmegen, Netherlands.,Epigenomics & Single Cell Biophysics Group, Department of Cell Biology, Radboud University, Nijmegen, Netherlands.,Department of Human Genetics, Radboud University Medical Center, Nijmegen, Netherlands
| | - Yutaka Negishi
- Radboud Institute for Molecular Life Sciences (RIMLS), Radboud University Medical Center, Nijmegen, Netherlands.,Epigenomics & Single Cell Biophysics Group, Department of Cell Biology, Radboud University, Nijmegen, Netherlands.,Department of Human Genetics, Radboud University Medical Center, Nijmegen, Netherlands
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7
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Martínez de Paz A, Josefowicz SZ. Signaling-to-chromatin pathways in the immune system. Immunol Rev 2021; 300:37-53. [PMID: 33644906 PMCID: PMC8548991 DOI: 10.1111/imr.12955] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 01/08/2021] [Accepted: 01/11/2021] [Indexed: 02/01/2023]
Abstract
Complex organisms are able to respond to diverse environmental cues by rapidly inducing specific transcriptional programs comprising a few dozen genes among thousands. The highly complex environment within the nucleus-a crowded milieu containing large genomes tightly condensed with histone proteins in the form of chromatin-makes inducible transcription a challenge for the cell, akin to the proverbial needle in a haystack. The different signaling pathways and transcription factors involved in the transmission of information from the cell surface to the nucleus have been readily explored, but not so much the specific mechanisms employed by the cell to ultimately instruct the chromatin changes necessary for a fast and robust transcription activation. Signaling pathways rely on cascades of protein kinases that, in addition to activating transcription factors can also activate the chromatin template by phosphorylating histone proteins, what we refer to as "signaling-to-chromatin." These pathways appear to be selectively employed and especially critical for driving inducible transcription in macrophages and likely in diverse other immune cell populations. Here, we discuss signaling-to-chromatin pathways with potential relevance in diverse immune cell populations together with chromatin related mechanisms that help to "solve" the needle in a haystack challenge of robust chromatin activation and inducible transcription.
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Affiliation(s)
- Alexia Martínez de Paz
- Laboratory of Epigenetics and Immunity, Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Steven Zvi Josefowicz
- Laboratory of Epigenetics and Immunity, Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, NY, USA
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8
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Differential Activation of P-TEFb Complexes in the Development of Cardiomyocyte Hypertrophy following Activation of Distinct G Protein-Coupled Receptors. Mol Cell Biol 2020; 40:MCB.00048-20. [PMID: 32341082 DOI: 10.1128/mcb.00048-20] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Accepted: 04/16/2020] [Indexed: 12/19/2022] Open
Abstract
Pathological cardiac hypertrophy is driven by neurohormonal activation of specific G protein-coupled receptors (GPCRs) in cardiomyocytes and is accompanied by large-scale changes in cardiomyocyte gene expression. These transcriptional changes require activity of positive transcription elongation factor b (P-TEFb), which is recruited to target genes by the bromodomain protein Brd4 or the super elongation complex (SEC). Here, we describe GPCR-specific regulation of these P-TEFb complexes and a novel mechanism for activating Brd4 in primary neonatal rat cardiomyocytes. The SEC was required for the hypertrophic response downstream of either the α1-adrenergic receptor (α1-AR) or the endothelin receptor (ETR). In contrast, Brd4 inhibition selectively impaired the α1-AR response. This was corroborated by the finding that the activation of α1-AR, but not ETR, increased Brd4 occupancy at promoters and superenhancers of hypertrophic genes. Transcriptome analysis demonstrated that the activation of both receptors initiated similar gene expression programs, but that Brd4 inhibition attenuated hypertrophic genes more robustly following α1-AR activation. Finally, we show that protein kinase A (PKA) is required for α1-AR stimulation of Brd4 chromatin occupancy. The differential role of the Brd4/P-TEFb complex in response to distinct GPCR pathways has potential clinical implications, as therapies targeting this complex are currently being explored for heart failure.
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9
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Negative elongation factor complex enables macrophage inflammatory responses by controlling anti-inflammatory gene expression. Nat Commun 2020; 11:2286. [PMID: 32385332 PMCID: PMC7210294 DOI: 10.1038/s41467-020-16209-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Accepted: 04/21/2020] [Indexed: 01/06/2023] Open
Abstract
Studies on macrophage gene expression have historically focused on events leading to RNA polymerase II recruitment and transcription initiation, whereas the contribution of post-initiation steps to macrophage activation remains poorly understood. Here, we report that widespread promoter-proximal RNA polymerase II pausing in resting macrophages is marked by co-localization of the negative elongation factor (NELF) complex and facilitated by PU.1. Upon inflammatory stimulation, over 60% of activated transcriptome is regulated by polymerase pause-release and a transient genome-wide NELF dissociation from chromatin, unexpectedly, independent of CDK9, a presumed NELF kinase. Genetic disruption of NELF in macrophages enhanced transcription of AP-1-encoding Fos and Jun and, consequently, AP-1 targets including Il10. Augmented expression of IL-10, a critical anti-inflammatory cytokine, in turn, attenuated production of pro-inflammatory mediators and, ultimately, macrophage-mediated inflammation in vivo. Together, these findings establish a previously unappreciated role of NELF in constraining transcription of inflammation inhibitors thereby enabling inflammatory macrophage activation. Macrophage activation is integral to innate immunity and inflammation, and involves transcriptome remodeling leading to the rapid upregulation of pro- and anti-inflammatory effector genes. Here the authors show that the negative elongation factor (NELF) complex controls the transcription of anti-inflammatory genes through Pol II pause release.
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10
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Lackey DE, Reis FCG, Isaac R, Zapata RC, El Ouarrat D, Lee YS, Bandyopadhyay G, Ofrecio JM, Oh DY, Osborn O. Adipocyte PU.1 knockout promotes insulin sensitivity in HFD-fed obese mice. Sci Rep 2019; 9:14779. [PMID: 31611602 PMCID: PMC6791934 DOI: 10.1038/s41598-019-51196-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Accepted: 09/26/2019] [Indexed: 12/27/2022] Open
Abstract
Insulin resistance is a key feature of obesity and type 2 diabetes. PU.1 is a master transcription factor predominantly expressed in macrophages but after HFD feeding PU.1 expression is also significantly increased in adipocytes. We generated adipocyte specific PU.1 knockout mice using adiponectin cre to investigate the role of PU.1 in adipocyte biology, insulin and glucose homeostasis. In HFD-fed obese mice systemic glucose tolerance and insulin sensitivity were improved in PU.1 AKO mice and clamp studies indicated improvements in both adipose and liver insulin sensitivity. At the level of adipose tissue, macrophage infiltration and inflammation was decreased and glucose uptake was increased in PU.1 AKO mice compared with controls. While PU.1 deletion in adipocytes did not affect the gene expression of PPARg itself, we observed increased expression of PPARg target genes in eWAT from HFD fed PU.1 AKO mice compared with controls. Furthermore, we observed decreased phosphorylation at serine 273 in PU.1 AKO mice compared with fl/fl controls, indicating that PPARg is more active when PU.1 expression is reduced in adipocytes. Therefore, in obesity the increased expression of PU.1 in adipocytes modifies the adipocyte PPARg cistrome resulting in impaired glucose tolerance and insulin sensitivity.
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Affiliation(s)
- Denise E Lackey
- Department of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA
| | - Felipe C G Reis
- Department of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA
| | - Roi Isaac
- Department of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA
| | - Rizaldy C Zapata
- Department of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA
| | - Dalila El Ouarrat
- Department of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA
| | - Yun Sok Lee
- Department of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA
| | - Gautam Bandyopadhyay
- Department of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA
| | - Jachelle M Ofrecio
- Department of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA
| | - Da Young Oh
- Touchstone Diabetes Center, Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, Texas, USA
| | - Olivia Osborn
- Department of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA.
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11
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Fok ET, Davignon L, Fanucchi S, Mhlanga MM. The lncRNA Connection Between Cellular Metabolism and Epigenetics in Trained Immunity. Front Immunol 2019; 9:3184. [PMID: 30761161 PMCID: PMC6361822 DOI: 10.3389/fimmu.2018.03184] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 12/28/2018] [Indexed: 11/13/2022] Open
Abstract
Trained immunity describes the ability of innate immune cells to form immunological memories of prior encounters with pathogens. Recollection of these memories during a secondary encounter manifests a broadly enhanced inflammatory response characterized by the increased transcription of innate immune genes. Despite this phenomenon having been described over a decade ago, our understanding of the molecular mechanisms responsible for this phenotype is still incomplete. Here we present an overview of the molecular events that lead to training. For the first time, we highlight the mechanistic role of a novel class of long non-coding RNAs (lncRNAs) in the establishment and maintenance of discrete, long lasting epigenetic modifications that are causal to the trained immune response. This recent insight fills in significant gaps in our understanding of trained immunity and reveals novel ways to exploit trained immunity for therapeutic purposes.
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Affiliation(s)
- Ezio T Fok
- Division of Chemical, Systems & Synthetic Biology, Department of Integrative Biomedical Sciences, Faculty of Health Sciences, Institute of Infectious Disease & Molecular Medicine, University of Cape Town, Cape Town, South Africa.,Gene Expression and Biophysics Group, ERA, CSIR Biosciences, Pretoria, South Africa
| | - Laurianne Davignon
- Division of Chemical, Systems & Synthetic Biology, Department of Integrative Biomedical Sciences, Faculty of Health Sciences, Institute of Infectious Disease & Molecular Medicine, University of Cape Town, Cape Town, South Africa
| | - Stephanie Fanucchi
- Division of Chemical, Systems & Synthetic Biology, Department of Integrative Biomedical Sciences, Faculty of Health Sciences, Institute of Infectious Disease & Molecular Medicine, University of Cape Town, Cape Town, South Africa.,Gene Expression and Biophysics Group, ERA, CSIR Biosciences, Pretoria, South Africa
| | - Musa M Mhlanga
- Division of Chemical, Systems & Synthetic Biology, Department of Integrative Biomedical Sciences, Faculty of Health Sciences, Institute of Infectious Disease & Molecular Medicine, University of Cape Town, Cape Town, South Africa.,Gene Expression and Biophysics Unit, Instituto de Medicina Molecular, Faculdade de Medicina Universidade de Lisboa, Lisbon, Portugal
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12
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Fanucchi S, Fok ET, Dalla E, Shibayama Y, Börner K, Chang EY, Stoychev S, Imakaev M, Grimm D, Wang KC, Li G, Sung WK, Mhlanga MM. Immune genes are primed for robust transcription by proximal long noncoding RNAs located in nuclear compartments. Nat Genet 2018; 51:138-150. [PMID: 30531872 DOI: 10.1038/s41588-018-0298-2] [Citation(s) in RCA: 141] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 10/30/2018] [Indexed: 12/22/2022]
Abstract
Accumulation of trimethylation of histone H3 at lysine 4 (H3K4me3) on immune-related gene promoters underlies robust transcription during trained immunity. However, the molecular basis for this remains unknown. Here we show three-dimensional chromatin topology enables immune genes to engage in chromosomal contacts with a subset of long noncoding RNAs (lncRNAs) we have defined as immune gene-priming lncRNAs (IPLs). We show that the prototypical IPL, UMLILO, acts in cis to direct the WD repeat-containing protein 5 (WDR5)-mixed lineage leukemia protein 1 (MLL1) complex across the chemokine promoters, facilitating their H3K4me3 epigenetic priming. This mechanism is shared amongst several trained immune genes. Training mediated by β-glucan epigenetically reprograms immune genes by upregulating IPLs in manner dependent on nuclear factor of activated T cells. The murine chemokine topologically associating domain lacks an IPL, and the Cxcl genes are not trained. Strikingly, the insertion of UMLILO into the chemokine topologically associating domain in mouse macrophages resulted in training of Cxcl genes. This provides strong evidence that lncRNA-mediated regulation is central to the establishment of trained immunity.
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Affiliation(s)
- Stephanie Fanucchi
- Gene Expression and Biophysics Group, Division of Chemical, Systems and Synthetic Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.,BTRI, CSIR Biosciences, Pretoria, South Africa
| | - Ezio T Fok
- Gene Expression and Biophysics Group, Division of Chemical, Systems and Synthetic Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.,BTRI, CSIR Biosciences, Pretoria, South Africa
| | - Emiliano Dalla
- Gene Expression and Biophysics Group, Division of Chemical, Systems and Synthetic Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.,Department of Medicine, Università degli Studi di Udine, Udine, Italy
| | - Youtaro Shibayama
- Gene Expression and Biophysics Group, Division of Chemical, Systems and Synthetic Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.,RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Kathleen Börner
- Department of Infectious Diseases/Virology, BioQuant Center, Heidelberg University Hospital, Heidelberg, Germany.,Heidelberg Partner Site, German Center for Infection Research (DZIF), Heidelberg, Germany
| | - Erin Y Chang
- Department of Dermatology, Stanford University, Stanford, CA, USA
| | - Stoyan Stoychev
- Biomedical Technologies Group, CSIR Biosciences, Pretoria, South Africa
| | - Maxim Imakaev
- Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Boston, MA, USA
| | - Dirk Grimm
- Department of Infectious Diseases/Virology, BioQuant Center, Heidelberg University Hospital, Heidelberg, Germany.,Heidelberg Partner Site, German Center for Infection Research (DZIF), Heidelberg, Germany.,Cluster of Excellence CellNetworks, Heidelberg, Germany
| | - Kevin C Wang
- Department of Dermatology, Stanford University, Stanford, CA, USA
| | - Guoliang Li
- College of Informatics, Huazhong Agricultural University, Wuhan, China
| | - Wing-Kin Sung
- School of Computing, National University of Singapore, Singapore, Singapore.,Genome Institute of Singapore, Singapore, Singapore
| | - Musa M Mhlanga
- Gene Expression and Biophysics Group, Division of Chemical, Systems and Synthetic Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa. .,Gene Expression and Biophysics Unit, Instituto de Medicina Molecular, Faculdade de Medicina Universidade de Lisboa, Lisbon, Portugal.
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13
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Meier-Soelch J, Jurida L, Weber A, Newel D, Kim J, Braun T, Schmitz ML, Kracht M. RNAi-Based Identification of Gene-Specific Nuclear Cofactor Networks Regulating Interleukin-1 Target Genes. Front Immunol 2018; 9:775. [PMID: 29755455 PMCID: PMC5934416 DOI: 10.3389/fimmu.2018.00775] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 03/28/2018] [Indexed: 12/22/2022] Open
Abstract
The potent proinflammatory cytokine interleukin (IL)-1 triggers gene expression through the NF-κB signaling pathway. Here, we investigated the cofactor requirements of strongly regulated IL-1 target genes whose expression is impaired in p65 NF-κB-deficient murine embryonic fibroblasts. By two independent small-hairpin (sh)RNA screens, we examined 170 genes annotated to encode nuclear cofactors for their role in Cxcl2 mRNA expression and identified 22 factors that modulated basal or IL-1-inducible Cxcl2 levels. The functions of 16 of these factors were validated for Cxcl2 and further analyzed for their role in regulation of 10 additional IL-1 target genes by RT-qPCR. These data reveal that each inducible gene has its own (quantitative) requirement of cofactors to maintain basal levels and to respond to IL-1. Twelve factors (Epc1, H2afz, Kdm2b, Kdm6a, Mbd3, Mta2, Phf21a, Ruvbl1, Sin3b, Suv420h1, Taf1, and Ube3a) have not been previously implicated in inflammatory cytokine functions. Bioinformatics analysis indicates that they are components of complex nuclear protein networks that regulate chromatin functions and gene transcription. Collectively, these data suggest that downstream from the essential NF-κB signal each cytokine-inducible target gene has further subtle requirements for individual sets of nuclear cofactors that shape its transcriptional activation profile.
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Affiliation(s)
- Johanna Meier-Soelch
- Rudolf Buchheim Institute of Pharmacology, Justus Liebig University Giessen, Giessen, Germany
| | - Liane Jurida
- Rudolf Buchheim Institute of Pharmacology, Justus Liebig University Giessen, Giessen, Germany
| | - Axel Weber
- Rudolf Buchheim Institute of Pharmacology, Justus Liebig University Giessen, Giessen, Germany
| | - Doris Newel
- Rudolf Buchheim Institute of Pharmacology, Justus Liebig University Giessen, Giessen, Germany
| | - Johnny Kim
- Max-Planck-Institute for Heart and Lung Research, Bad Nauheim, Germany
| | - Thomas Braun
- Max-Planck-Institute for Heart and Lung Research, Bad Nauheim, Germany
| | - M Lienhard Schmitz
- Institute of Biochemistry, Justus Liebig University Giessen, Giessen, Germany
| | - Michael Kracht
- Rudolf Buchheim Institute of Pharmacology, Justus Liebig University Giessen, Giessen, Germany
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14
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Sacta MA, Tharmalingam B, Coppo M, Rollins DA, Deochand DK, Benjamin B, Yu L, Zhang B, Hu X, Li R, Chinenov Y, Rogatsky I. Gene-specific mechanisms direct glucocorticoid-receptor-driven repression of inflammatory response genes in macrophages. eLife 2018; 7:34864. [PMID: 29424686 PMCID: PMC5821458 DOI: 10.7554/elife.34864] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2018] [Accepted: 01/28/2018] [Indexed: 01/13/2023] Open
Abstract
The glucocorticoid receptor (GR) potently represses macrophage-elicited inflammation, however, the underlying mechanisms remain obscure. Our genome-wide analysis in mouse macrophages reveals that pro-inflammatory paused genes, activated via global negative elongation factor (NELF) dissociation and RNA Polymerase (Pol)2 release from early elongation arrest, and non-paused genes, induced by de novo Pol2 recruitment, are equally susceptible to acute glucocorticoid repression. Moreover, in both cases the dominant mechanism involves rapid GR tethering to p65 at NF-kB-binding sites. Yet, specifically at paused genes, GR activation triggers widespread promoter accumulation of NELF, with myeloid cell-specific NELF deletion conferring glucocorticoid resistance. Conversely, at non-paused genes, GR attenuates the recruitment of p300 and histone acetylation, leading to a failure to assemble BRD4 and Mediator at promoters and enhancers, ultimately blocking Pol2 initiation. Thus, GR displays no preference for a specific pro-inflammatory gene class; however, it effects repression by targeting distinct temporal events and components of transcriptional machinery.
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Affiliation(s)
- Maria A Sacta
- Weill Cornell/ Rockefeller/ Sloan Kettering Tri-Institutional MD-PhD Program, New York, United States.,Hospital for Special Surgery Research Institute, The David Rosensweig Genomics Center, New York, United States.,Graduate Program in Immunology and Microbial Pathogenesis, Weill Cornell Graduate School of Medical Sciences, New York, United States
| | - Bowranigan Tharmalingam
- Hospital for Special Surgery Research Institute, The David Rosensweig Genomics Center, New York, United States
| | - Maddalena Coppo
- Hospital for Special Surgery Research Institute, The David Rosensweig Genomics Center, New York, United States
| | - David A Rollins
- Hospital for Special Surgery Research Institute, The David Rosensweig Genomics Center, New York, United States.,Graduate Program in Immunology and Microbial Pathogenesis, Weill Cornell Graduate School of Medical Sciences, New York, United States
| | - Dinesh K Deochand
- Hospital for Special Surgery Research Institute, The David Rosensweig Genomics Center, New York, United States
| | - Bradley Benjamin
- Hospital for Special Surgery Research Institute, The David Rosensweig Genomics Center, New York, United States
| | - Li Yu
- Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing, China
| | - Bin Zhang
- Institute for Immunology and School of Medicine, Tsinghua University, Beijing, China
| | - Xiaoyu Hu
- Hospital for Special Surgery Research Institute, The David Rosensweig Genomics Center, New York, United States.,Institute for Immunology and School of Medicine, Tsinghua University, Beijing, China
| | - Rong Li
- Department of Molecular Medicine, The University of Texas Health Science Center at San Antonio, San Antonio, United States
| | - Yurii Chinenov
- Hospital for Special Surgery Research Institute, The David Rosensweig Genomics Center, New York, United States
| | - Inez Rogatsky
- Hospital for Special Surgery Research Institute, The David Rosensweig Genomics Center, New York, United States.,Graduate Program in Immunology and Microbial Pathogenesis, Weill Cornell Graduate School of Medical Sciences, New York, United States
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15
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Imashimizu M, Lukatsky DB. Transcription pausing: biological significance of thermal fluctuations biased by repetitive genomic sequences. Transcription 2017; 9:196-203. [PMID: 29105534 PMCID: PMC5927657 DOI: 10.1080/21541264.2017.1393492] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Transcription of DNA by RNA polymerase (RNAP) takes place in a cell environment dominated by thermal fluctuations. How are transcription reactions including initiation, elongation, and termination on genomic DNA so well-controlled during such fluctuations? A recent statistical mechanical approach using high-throughput sequencing data reveals that repetitive DNA sequence elements embedded into a genomic sequence provide the key mechanism to functionally bias the fluctuations of transcription elongation complexes. In particular, during elongation pausing, such repetitive sequence elements can increase the magnitude of one-dimensional diffusion of the RNAP enzyme on the DNA upstream of the pausing site, generating a large variation in the dwell times of RNAP pausing under the control of these genomic signals.
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Affiliation(s)
- Masahiko Imashimizu
- a Institute of Medical Science , University of Tokyo , Minato-ku, Tokyo , Japan
| | - David B Lukatsky
- b Department of Chemistry , Ben-Gurion University of the Negev , Be'er Sheva , Israel
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16
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Treuter E, Fan R, Huang Z, Jakobsson T, Venteclef N. Transcriptional repression in macrophages-basic mechanisms and alterations in metabolic inflammatory diseases. FEBS Lett 2017; 591:2959-2977. [DOI: 10.1002/1873-3468.12850] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Revised: 09/11/2017] [Accepted: 09/11/2017] [Indexed: 01/21/2023]
Affiliation(s)
- Eckardt Treuter
- Department of Biosciences and Nutrition; Center for Innovative Medicine (CIMED); Karolinska Institutet; Huddinge Sweden
| | - Rongrong Fan
- Department of Biosciences and Nutrition; Center for Innovative Medicine (CIMED); Karolinska Institutet; Huddinge Sweden
| | - Zhiqiang Huang
- Department of Biosciences and Nutrition; Center for Innovative Medicine (CIMED); Karolinska Institutet; Huddinge Sweden
| | - Tomas Jakobsson
- Department of Laboratory Medicine; Karolinska Institutet; Huddinge Sweden
| | - Nicolas Venteclef
- UMR_S 1138 Cordeliers Research; Institut National de la Santé et de la Recherche Médicale (INSERM); Sorbonne Universités; Université Pierre et Marie-Curie; Paris France
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17
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The NF-κB-dependent and -independent transcriptome and chromatin landscapes of human coronavirus 229E-infected cells. PLoS Pathog 2017; 13:e1006286. [PMID: 28355270 PMCID: PMC5386326 DOI: 10.1371/journal.ppat.1006286] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 04/10/2017] [Accepted: 03/09/2017] [Indexed: 12/20/2022] Open
Abstract
Coronavirus replication takes place in the host cell cytoplasm and triggers inflammatory gene expression by poorly characterized mechanisms. To obtain more insight into the signals and molecular events that coordinate global host responses in the nucleus of coronavirus-infected cells, first, transcriptome dynamics was studied in human coronavirus 229E (HCoV-229E)-infected A549 and HuH7 cells, respectively, revealing a core signature of upregulated genes in these cells. Compared to treatment with the prototypical inflammatory cytokine interleukin(IL)-1, HCoV-229E replication was found to attenuate the inducible activity of the transcription factor (TF) NF-κB and to restrict the nuclear concentration of NF-κB subunits by (i) an unusual mechanism involving partial degradation of IKKβ, NEMO and IκBα and (ii) upregulation of TNFAIP3 (A20), although constitutive IKK activity and basal TNFAIP3 expression levels were shown to be required for efficient virus replication. Second, we characterized actively transcribed genomic regions and enhancers in HCoV-229E-infected cells and systematically correlated the genome-wide gene expression changes with the recruitment of Ser5-phosphorylated RNA polymerase II and prototypical histone modifications (H3K9ac, H3K36ac, H4K5ac, H3K27ac, H3K4me1). The data revealed that, in HCoV-infected (but not IL-1-treated) cells, an extensive set of genes was activated without inducible p65 NF-κB being recruited. Furthermore, both HCoV-229E replication and IL-1 were shown to upregulate a small set of genes encoding immunomodulatory factors that bind p65 at promoters and require IKKβ activity and p65 for expression. Also, HCoV-229E and IL-1 activated a common set of 440 p65-bound enhancers that differed from another 992 HCoV-229E-specific enhancer regions by distinct TF-binding motif combinations. Taken together, the study shows that cytoplasmic RNA viruses fine-tune NF-κB signaling at multiple levels and profoundly reprogram the host cellular chromatin landscape, thereby orchestrating the timely coordinated expression of genes involved in multiple signaling, immunoregulatory and metabolic processes. Coronaviruses are major human and animal pathogens. They belong to a family of plus-strand RNA viruses that have extremely large genomes and encode a variety of proteins involved in virus-host interactions. The four common coronaviruses (HCoV-229E, NL63, OC43, HKU1) cause mainly upper respiratory tract infections, while zoonotic coronaviruses (SARS-CoV and MERS-CoV) cause severe lung disease, including acute respiratory distress syndrome (ARDS). The molecular basis for this fundamentally different pathology is incompletely understood. Our study provides a genome-wide investigation of epigenetic changes occurring in response to HCoV-229E. We identify at high resolution a large number of regulatory regions in the genome of infected cells that coordinate de novo gene transcription. Many of these genes have immunomodulatory functions and, most likely, contribute to limiting viral replication, while other factors may promote viral replication. The study provides an intriguing example of a virus that completes its entire life cycle in the cytoplasm while sending multiple signals to the nuclear chromatin compartment to adjust the host cell repertoire of transcribed genes. The approach taken in this study is expected to provide a suitable framework for future studies aimed at dissecting and comparing host responses to representative coronaviruses with different pathogenic potential in humans.
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18
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Abstract
Coronaviruses (CoV) comprise a large group of emerging human and animal pathogens, including the highly pathogenic severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV) strains. The molecular mechanisms regulating emerging coronavirus pathogenesis are complex and include virus–host interactions associated with entry, replication, egress and innate immune control. Epigenetics research investigates the genetic and non-genetic factors that regulate phenotypic variation, usually caused by external and environmental factors that alter host expression patterns and performance without any change in the underlying genotype. Epigenetic modifications, such as histone modifications, DNA methylation, chromatin remodeling, and non-coding RNAs, function as important regulators that remodel host chromatin, altering host expression patterns and networks in a highly flexible manner. For most of the past two and a half decades, research has focused on the molecular mechanisms by which RNA viruses antagonize the signaling and sensing components that regulate induction of the host innate immune and antiviral defense programs upon infection. More recently, a growing body of evidence supports the hypothesis that viruses, even lytic RNA viruses that replicate in the cytoplasm, have developed intricate, highly evolved, and well-coordinated processes that are designed to regulate the host epigenome, and control host innate immune antiviral defense processes, thereby promoting robust virus replication and pathogenesis. In this article, we discuss the strategies that are used to evaluate the mechanisms by which viruses regulate the host epigenome, especially focusing on highly pathogenic respiratory RNA virus infections as a model. By combining measures of epigenome reorganization with RNA and proteomic datasets, we articulate a spatial-temporal data integration approach to identify regulatory genomic clusters and regions that play a crucial role in the host’s innate immune response, thereby defining a new viral antagonism mechanism following emerging coronavirus infection.
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19
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Dumler JS, Sinclair SH, Pappas-Brown V, Shetty AC. Genome-Wide Anaplasma phagocytophilum AnkA-DNA Interactions Are Enriched in Intergenic Regions and Gene Promoters and Correlate with Infection-Induced Differential Gene Expression. Front Cell Infect Microbiol 2016; 6:97. [PMID: 27703927 PMCID: PMC5028410 DOI: 10.3389/fcimb.2016.00097] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 08/26/2016] [Indexed: 12/16/2022] Open
Abstract
Anaplasma phagocytophilum, an obligate intracellular prokaryote, infects neutrophils, and alters cardinal functions via reprogrammed transcription. Large contiguous regions of neutrophil chromosomes are differentially expressed during infection. Secreted A. phagocytophilum effector AnkA transits into the neutrophil or granulocyte nucleus to complex with DNA in heterochromatin across all chromosomes. AnkA binds to gene promoters to dampen cis-transcription and also has features of matrix attachment region (MAR)-binding proteins that regulate three-dimensional chromatin architecture and coordinate transcriptional programs encoded in topologically-associated chromatin domains. We hypothesize that identification of additional AnkA binding sites will better delineate how A. phagocytophilum infection results in reprogramming of the neutrophil genome. Using AnkA-binding ChIP-seq, we showed that AnkA binds broadly throughout all chromosomes in a reproducible pattern, especially at: (i) intergenic regions predicted to be MARs; (ii) within predicted lamina-associated domains; and (iii) at promoters ≤ 3000 bp upstream of transcriptional start sites. These findings provide genome-wide support for AnkA as a regulator of cis-gene transcription. Moreover, the dominant mark of AnkA in distal intergenic regions known to be AT-enriched, coupled with frequent enrichment in the nuclear lamina, provides strong support for its role as a MAR-binding protein and genome “re-organizer.” AnkA must be considered a prime candidate to promote neutrophil reprogramming and subsequent functional changes that belie improved microbial fitness and pathogenicity.
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Affiliation(s)
- J Stephen Dumler
- Department of Pathology, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences Bethesda, MD, USA
| | | | - Valeria Pappas-Brown
- Department of Pathology, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences Bethesda, MD, USA
| | - Amol C Shetty
- Informatics Resource Center, Institute for Genome Sciences, University of Maryland Baltimore, MD, USA
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20
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Bahrami S, Drabløs F. Gene regulation in the immediate-early response process. Adv Biol Regul 2016; 62:37-49. [PMID: 27220739 DOI: 10.1016/j.jbior.2016.05.001] [Citation(s) in RCA: 256] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Accepted: 05/03/2016] [Indexed: 05/13/2023]
Abstract
Immediate-early genes (IEGs) can be activated and transcribed within minutes after stimulation, without the need for de novo protein synthesis, and they are stimulated in response to both cell-extrinsic and cell-intrinsic signals. Extracellular signals are transduced from the cell surface, through receptors activating a chain of proteins in the cell, in particular extracellular-signal-regulated kinases (ERKs), mitogen-activated protein kinases (MAPKs) and members of the RhoA-actin pathway. These communicate through a signaling cascade by adding phosphate groups to neighboring proteins, and this will eventually activate and translocate TFs to the nucleus and thereby induce gene expression. The gene activation also involves proximal and distal enhancers that interact with promoters to simulate gene expression. The immediate-early genes have essential biological roles, in particular in stress response, like the immune system, and in differentiation. Therefore they also have important roles in various diseases, including cancer development. In this paper we summarize some recent advances on key aspects of the activation and regulation of immediate-early genes.
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Affiliation(s)
- Shahram Bahrami
- Department of Cancer Research and Molecular Medicine, NTNU - Norwegian University of Science and Technology, NO-7491 Trondheim, Norway; St. Olavs Hospital, Trondheim University Hospital, NO-7006 Trondheim, Norway.
| | - Finn Drabløs
- Department of Cancer Research and Molecular Medicine, NTNU - Norwegian University of Science and Technology, NO-7491 Trondheim, Norway.
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21
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The transcriptional repressor Hes1 attenuates inflammation by regulating transcription elongation. Nat Immunol 2016; 17:930-7. [PMID: 27322654 PMCID: PMC4955730 DOI: 10.1038/ni.3486] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2016] [Accepted: 05/05/2016] [Indexed: 12/15/2022]
Abstract
Most of the known regulatory mechanisms that curb inflammatory gene expression target pre-transcription-initiation steps, and evidence for post-initiation regulation of inflammatory gene expression remains scarce. We found that the transcriptional repressor Hes1 suppressed production of CXCL1, a chemokine that is crucial for recruiting neutrophils. Hes1 negatively regulated neutrophil recruitment in vivo in a manner that was dependent on macrophage-produced CXCL1, and it attenuated the severity of inflammatory arthritis. Mechanistically, inhibition of Cxcl1 expression by Hes1 did not involve modification of transcription initiation. Instead, Hes1 inhibited signal-induced recruitment of the positive transcription-elongation complex P-TEFb and thereby prevented phosphorylation of RNA polymerase II at Ser2 and productive elongation. Thus, our results identify Hes1 as a homeostatic suppressor of inflammatory responses that exerts its suppressive function by regulating transcription elongation.
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22
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Glass CK, Natoli G. Molecular control of activation and priming in macrophages. Nat Immunol 2016; 17:26-33. [PMID: 26681459 DOI: 10.1038/ni.3306] [Citation(s) in RCA: 352] [Impact Index Per Article: 44.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 09/28/2015] [Indexed: 11/09/2022]
Abstract
In tissues, macrophages are exposed to metabolic, homeostatic and immunoregulatory signals of local or systemic origin that influence their basal functions and responses to danger signals. Signal-transduction pathways regulated by extracellular signals are coupled to distinct sets of broadly expressed stimulus-regulated transcription factors whose ability to elicit gene-expression changes is influenced by the accessibility of their binding sites in the macrophage genome. In turn, accessibility of macrophage-specific transcriptional regulatory elements (enhancers and promoters) is specified by transcription factors that determine the macrophage lineage or impose their tissue-specific properties. Here we review recent findings that advance the understanding of mechanisms underlying priming and signal-dependent activation of macrophages and discuss the effect of genetic variation on these processes.
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Affiliation(s)
- Christopher K Glass
- Department of Cellular and Molecular Medicine and Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, California, USA
| | - Gioacchino Natoli
- Department of Experimental Oncology, European Institute of Oncology, Milan, Italy
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23
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Santin I, Dos Santos RS, Eizirik DL. Pancreatic Beta Cell Survival and Signaling Pathways: Effects of Type 1 Diabetes-Associated Genetic Variants. Methods Mol Biol 2016; 1433:21-54. [PMID: 26936771 DOI: 10.1007/7651_2015_291] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Type 1 diabetes (T1D) is a complex autoimmune disease in which pancreatic beta cells are specifically destroyed by the immune system. The disease has an important genetic component and more than 50 loci across the genome have been associated with risk of developing T1D. The molecular mechanisms by which these putative T1D candidate genes modulate disease risk, however, remain poorly characterized and little is known about their effects in pancreatic beta cells. Functional studies in in vitro models of pancreatic beta cells, based on techniques to inhibit or overexpress T1D candidate genes, allow the functional characterization of several T1D candidate genes. This requires a multistage procedure comprising two major steps, namely accurate selection of genes of potential interest and then in vitro and/or in vivo mechanistic approaches to characterize their role in pancreatic beta cell dysfunction and death in T1D. This chapter details the methods and settings used by our groups to characterize the role of T1D candidate genes on pancreatic beta cell survival and signaling pathways, with particular focus on potentially relevant pathways in the pathogenesis of T1D, i.e., inflammation and innate immune responses, apoptosis, beta cell metabolism and function.
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Affiliation(s)
- Izortze Santin
- ULB Center for Diabetes Research, Medical Faculty, Université Libre de Bruxelles (ULB), Brussels, Belgium.
- Endocrinology and Diabetes Research Group, BioCruces Health Research Institute, CIBERDEM, Spain.
| | - Reinaldo S Dos Santos
- ULB Center for Diabetes Research, Medical Faculty, Université Libre de Bruxelles (ULB), Brussels, Belgium
| | - Decio L Eizirik
- ULB Center for Diabetes Research, Medical Faculty, Université Libre de Bruxelles (ULB), Brussels, Belgium
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24
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Transcriptional Activation of Inflammatory Genes: Mechanistic Insight into Selectivity and Diversity. Biomolecules 2015; 5:3087-111. [PMID: 26569329 PMCID: PMC4693271 DOI: 10.3390/biom5043087] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Revised: 09/11/2015] [Accepted: 10/28/2015] [Indexed: 12/11/2022] Open
Abstract
Acute inflammation, an integral part of host defence and immunity, is a highly conserved cellular response to pathogens and other harmful stimuli. An inflammatory stimulation triggers transcriptional activation of selective pro-inflammatory genes that carry out specific functions such as anti-microbial activity or tissue healing. Based on the nature of inflammatory stimuli, an extensive exploitation of selective transcriptional activations of pro-inflammatory genes is performed by the host to ensure a defined inflammatory response. Inflammatory signal transductions are initiated by the recognition of inflammatory stimuli by transmembrane receptors, followed by the transmission of the signals to the nucleus for differential gene activations. The differential transcriptional activation of pro-inflammatory genes is precisely controlled by the selective binding of transcription factors to the promoters of these genes. Among a number of transcription factors identified to date, NF-κB still remains the most prominent and studied factor for its diverse range of selective transcriptional activities. Differential transcriptional activities of NF-κB are dictated by post-translational modifications, specificities in dimer formation, and variability in activation kinetics. Apart from the differential functions of transcription factors, the transcriptional activation of selective pro-inflammatory genes is also governed by chromatin structures, epigenetic markers, and other regulators as the field is continuously expanding.
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25
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Chauhan A, Quenum FZ, Abbas A, Bradley DS, Nechaev S, Singh BB, Sharma J, Mishra BB. Epigenetic Modulation of Microglial Inflammatory Gene Loci in Helminth-Induced Immune Suppression: Implications for Immune Regulation in Neurocysticercosis. ASN Neuro 2015; 7:7/4/1759091415592126. [PMID: 26148848 PMCID: PMC4552224 DOI: 10.1177/1759091415592126] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
In neurocysticercosis, parasite-induced immune suppressive effects are thought to play an important role in enabling site-specific inhibition of inflammatory responses to infections. It is axiomatic that microglia-mediated (M1 proinflammatory) response causes central nervous system inflammation; however, the mechanisms by which helminth parasites modulate microglia activation remain poorly understood. Here, we show that microglia display a diminished expression of M1-inflammatory mediators such as tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and nitric oxide synthase 2 (NOS2) in murine neurocysticercosis. Microglia also exhibited a lack of myeloid cell maturation marker major histocompatibility complex (MHC)-II in these parasite-infected brains. Treatment of microglia with helminth soluble/secreted factors (HSFs) in vitro did not induce expression of M1-inflammatory signature molecule NOS2 as well as MHC-II in primary microglia. However, HSF treatment completely inhibited lipopolysaccharide-induced increase in expression of MHC-II, NOS2 and nitric oxide production in these cells. As epigenetic modulation of chromatin states that regulates recruitment of RNA polymerase II (Pol-II) is a key regulatory step in determining gene expression and functional outcome, we next evaluated whether HSF induced modulation of these phenomenon in microglia in vitro. Indeed, HSF downregulated Pol-II recruitment to the promoter region of TNF-α, IL-6, NOS2, MHC-II, and transcription factor CIITA (a regulator of MHC-II expression), by itself. Moreover, HSF suppressed the lipopolysaccharide-induced increase in Pol-II recruitment as well. In addition, HSF exposure reduced the positive histone marks H3K4Me3 and H3K9/14Ac at the promoter of TNF-α, IL-6, NOS2, MHC-II, and CIITA. These studies provide a novel mechanistic insight into helminth-mediated immune suppression in microglia via modulation of epigenetic processes.
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Affiliation(s)
- Arun Chauhan
- Department of Basic Sciences, School of Medicine and Health Sciences, The University of North Dakota, Grand Forks, ND, USA
| | - Fredice Z Quenum
- Department of Basic Sciences, School of Medicine and Health Sciences, The University of North Dakota, Grand Forks, ND, USA
| | - Ata Abbas
- Department of Basic Sciences, School of Medicine and Health Sciences, The University of North Dakota, Grand Forks, ND, USA
| | - David S Bradley
- Department of Basic Sciences, School of Medicine and Health Sciences, The University of North Dakota, Grand Forks, ND, USA
| | - Sergei Nechaev
- Department of Basic Sciences, School of Medicine and Health Sciences, The University of North Dakota, Grand Forks, ND, USA
| | - Brij B Singh
- Department of Basic Sciences, School of Medicine and Health Sciences, The University of North Dakota, Grand Forks, ND, USA
| | - Jyotika Sharma
- Department of Basic Sciences, School of Medicine and Health Sciences, The University of North Dakota, Grand Forks, ND, USA
| | - Bibhuti B Mishra
- Department of Basic Sciences, School of Medicine and Health Sciences, The University of North Dakota, Grand Forks, ND, USA
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26
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Scruggs BS, Gilchrist DA, Nechaev S, Muse GW, Burkholder A, Fargo DC, Adelman K. Bidirectional Transcription Arises from Two Distinct Hubs of Transcription Factor Binding and Active Chromatin. Mol Cell 2015; 58:1101-12. [PMID: 26028540 DOI: 10.1016/j.molcel.2015.04.006] [Citation(s) in RCA: 158] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Revised: 01/29/2015] [Accepted: 04/01/2015] [Indexed: 11/26/2022]
Abstract
Anti-sense transcription originating upstream of mammalian protein-coding genes is a well-documented phenomenon, but remarkably little is known about the regulation or function of anti-sense promoters and the non-coding RNAs they generate. Here we define at nucleotide resolution the divergent transcription start sites (TSSs) near mouse mRNA genes. We find that coupled sense and anti-sense TSSs precisely define the boundaries of a nucleosome-depleted region (NDR) that is highly enriched in transcription factor (TF) motifs. Notably, as the distance between sense and anti-sense TSSs increases, so does the size of the NDR, the level of signal-dependent TF binding, and gene activation. We further discover a group of anti-sense TSSs in macrophages with an enhancer-like chromatin signature. Interestingly, this signature identifies divergent promoters that are activated during immune challenge. We propose that anti-sense promoters serve as platforms for TF binding and establishment of active chromatin to further regulate or enhance sense-strand mRNA expression.
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Affiliation(s)
- Benjamin S Scruggs
- Epigenetics and Stem Cell Biology Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | - Daniel A Gilchrist
- Epigenetics and Stem Cell Biology Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | - Sergei Nechaev
- Epigenetics and Stem Cell Biology Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | - Ginger W Muse
- Epigenetics and Stem Cell Biology Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | - Adam Burkholder
- Center for Integrative Bioinformatics, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | - David C Fargo
- Center for Integrative Bioinformatics, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | - Karen Adelman
- Epigenetics and Stem Cell Biology Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA.
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Imashimizu M, Takahashi H, Oshima T, McIntosh C, Bubunenko M, Court DL, Kashlev M. Visualizing translocation dynamics and nascent transcript errors in paused RNA polymerases in vivo. Genome Biol 2015; 16:98. [PMID: 25976475 PMCID: PMC4457086 DOI: 10.1186/s13059-015-0666-5] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Accepted: 05/05/2015] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND Transcription elongation is frequently interrupted by pausing signals in DNA, with downstream effects on gene expression. Transcription errors also induce prolonged pausing, which can lead to a destabilized genome by interfering with DNA replication. Mechanisms of pausing associated with translocation blocks and misincorporation have been characterized in vitro, but not in vivo. RESULTS We investigate the pausing pattern of RNA polymerase (RNAP) in Escherichia coli by a novel approach, combining native elongating transcript sequencing (NET-seq) with RNase footprinting of the transcripts (RNET-seq). We reveal that the G-dC base pair at the 5' end of the RNA-DNA hybrid interferes with RNAP translocation. The distance between the 5' G-dC base pair and the 3' end of RNA fluctuates over a three-nucleotide width. Thus, the G-dC base pair can induce pausing in post-translocated, pre-translocated, and backtracked states of RNAP. Additionally, a CpG sequence of the template DNA strand spanning the active site of RNAP inhibits elongation and induces G-to-A errors, which leads to backtracking of RNAP. Gre factors efficiently proofread the errors and rescue the backtracked complexes. We also find that pausing events are enriched in the 5' untranslated region and antisense transcription of mRNA genes and are reduced in rRNA genes. CONCLUSIONS In E. coli, robust transcriptional pausing involves RNAP interaction with G-dC at the upstream end of the RNA-DNA hybrid, which interferes with translocation. CpG DNA sequences induce transcriptional pausing and G-to-A errors.
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Affiliation(s)
- Masahiko Imashimizu
- Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702, USA.
| | - Hiroki Takahashi
- Medical Mycology Research Center, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba, 260-8673, Japan.
| | - Taku Oshima
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5, Ikoma, Nara, 630-0192, Japan.
| | - Carl McIntosh
- Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702, USA.
| | - Mikhail Bubunenko
- Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702, USA.
| | - Donald L Court
- Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702, USA.
| | - Mikhail Kashlev
- Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702, USA.
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Fowler T, Garruss AS, Ghosh A, De S, Becker KG, Wood WH, Weirauch MT, Smale ST, Aronow B, Sen R, Roy AL. Divergence of transcriptional landscape occurs early in B cell activation. Epigenetics Chromatin 2015; 8:20. [PMID: 25987903 PMCID: PMC4434543 DOI: 10.1186/s13072-015-0012-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 05/01/2015] [Indexed: 12/15/2022] Open
Abstract
Background Signaling via B cell receptor (BCR) and Toll-like receptors (TLRs) results in activation of B cells with distinct physiological outcomes, but transcriptional regulatory mechanisms that drive activation and distinguish these pathways remain unknown. Results Two hours after ligand exposure RNA-seq, ChIP-seq and computational methods reveal that BCR- or TLR-mediated activation of primary resting B cells proceeds via a large set of shared and a smaller subset of distinct signal-selective transcriptional responses. BCR stimulation resulted in increased global recruitment of RNA Pol II to promoters that appear to transit slowly to downstream regions. Conversely, lipopolysaccharide (LPS) stimulation involved an enhanced RNA Pol II transition from initiating to elongating mode accompanied by greater H3K4me3 activation markings compared to BCR stimulation. These rapidly diverging transcriptomic landscapes also show distinct repressing (H3K27me3) histone signatures, mutually exclusive transcription factor binding in promoters, and unique miRNA profiles. Conclusions Upon examination of genome-wide transcription and regulatory elements, we conclude that the B cell commitment to different activation states occurs much earlier than previously thought and involves a multi-faceted receptor-specific transcriptional landscape. Electronic supplementary material The online version of this article (doi:10.1186/s13072-015-0012-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Trent Fowler
- Department of Developmental, Chemical and Molecular Biology, Sackler School of Biomedical Science, Tufts University School of Medicine, 150 Harrison Avenue, Boston, MA 02111 USA
| | - Alexander S Garruss
- Wyss Institute for Biologically Inspired Engineering, Harvard University and Department of Genetics, Harvard Medical School, Boston, MA 02115 USA
| | - Amalendu Ghosh
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, Baltimore, MD 21224 USA
| | - Supriyo De
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, Baltimore, MD 21224 USA ; Gene Expression Unit, Laboratory of Genetics, National Institute on Aging, Baltimore, MD 21224 USA
| | - Kevin G Becker
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, Baltimore, MD 21224 USA ; Gene Expression Unit, Laboratory of Genetics, National Institute on Aging, Baltimore, MD 21224 USA
| | - William H Wood
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, Baltimore, MD 21224 USA ; Gene Expression Unit, Laboratory of Genetics, National Institute on Aging, Baltimore, MD 21224 USA
| | - Matthew T Weirauch
- Center for Autoimmune Genomics and Etiology (CAGE) and Divisions of Biomedical Informatics and Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229 USA
| | - Stephen T Smale
- Department of Microbiology, Immunology, and Molecular Genetics, UCLA, Los Angeles, CA 90095 USA
| | - Bruce Aronow
- Center for Autoimmune Genomics and Etiology (CAGE) and Divisions of Biomedical Informatics and Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229 USA
| | - Ranjan Sen
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, Baltimore, MD 21224 USA
| | - Ananda L Roy
- Department of Developmental, Chemical and Molecular Biology, Sackler School of Biomedical Science, Tufts University School of Medicine, 150 Harrison Avenue, Boston, MA 02111 USA
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Rollins DA, Coppo M, Rogatsky I. Minireview: nuclear receptor coregulators of the p160 family: insights into inflammation and metabolism. Mol Endocrinol 2015; 29:502-17. [PMID: 25647480 DOI: 10.1210/me.2015-1005] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Nuclear receptor coactivators (NCOAs) are multifunctional transcriptional coregulators for a growing number of signal-activated transcription factors. The members of the p160 family (NCOA1/2/3) are increasingly recognized as essential and nonredundant players in a number of physiological processes. In particular, accumulating evidence points to the pivotal roles that these coregulators play in inflammatory and metabolic pathways, both under homeostasis and in disease. Given that chronic inflammation of metabolic tissues ("metainflammation") is a driving force for the widespread epidemic of obesity, insulin resistance, cardiovascular disease, and associated comorbidities, deciphering the role of NCOAs in "normal" vs "pathological" inflammation and in metabolic processes is indeed a subject of extreme biomedical importance. Here, we review the evolving and, at times, contradictory, literature on the pleiotropic functions of NCOA1/2/3 in inflammation and metabolism as related to nuclear receptor actions and beyond. We then briefly discuss the potential utility of NCOAs as predictive markers for disease and/or possible therapeutic targets once a better understanding of their molecular and physiological actions is achieved.
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Affiliation(s)
- David A Rollins
- Hospital for Special Surgery (D.A.R., M.C., I.R.), The David Rosensweig Genomics Center, New York, New York 10021; and Graduate Program in Immunology and Microbial Pathogenesis (D.A.R., I.R.), Weill Cornell Graduate School of Medical Sciences, New York, New York 10021
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Saccani S, Trabucchi M. Regulation of stimulus-inducible gene expression in myeloid cells. Semin Immunol 2015; 27:33-43. [DOI: 10.1016/j.smim.2015.02.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 02/14/2015] [Accepted: 02/19/2015] [Indexed: 12/16/2022]
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