Building regulatory landscapes: enhancer recruits cohesin to create contact domains, engage CTCF sites and activate distant genes

2021 ◽  
Author(s):  
Niels J. Rinzema ◽  
Konstantinos Sofiadis ◽  
Sjoerd J. D. Tjalsma ◽  
Marjon J.A.M. Verstegen ◽  
Yuva Oz ◽  
...  
Keyword(s):  
Transcription Initiation ◽  
Target Genes ◽  
Gene Promoters ◽  
Topological Domains ◽  
Developmental Gene Expression ◽  
Chromatin Looping ◽  
Dna Elements ◽  
And Control ◽  
Transcriptional Output ◽  
Regulatory Landscapes

ABSTRACTDevelopmental gene expression is often controlled by distal tissue-specific enhancers. Enhancer action is restricted to topological chromatin domains, typically formed by cohesin-mediated loop extrusion between CTCF-associated boundaries. To better understand how individual regulatory DNA elements form topological domains and control expression, we used a bottom-up approach, building active regulatory landscapes of different sizes in inactive chromatin. We demonstrate that transcriptional output and protection against gene silencing reduces with increased enhancer distance, but that enhancer contact frequencies alone do not dictate transcription activity. The enhancer recruits cohesin to stimulate the formation of local chromatin contact domains and activate flanking CTCF sites for engagement in chromatin looping. Small contact domains can support strong and stable expression of distant genes. The enhancer requires transcription factors and mediator to activate genes over all distance ranges, but relies on cohesin exclusively for the activation of distant genes. Our work supports a model that assigns two functions to enhancers: its classic role to stimulate transcription initiation and elongation from target gene promoters and a role to recruit cohesin for the creation of contact domains, the engagement of flanking CTCF sites in chromatin looping, and the activation of distal target genes.

scholarly journals Orphan CpG islands boost the regulatory activity of poised enhancers and dictate the responsiveness of their target genes

2020 ◽  
Author(s):  
Tomás Pachano ◽  
Víctor Sánchez-Gaya ◽  
María Mariner-Faulí ◽  
Thais Ealo ◽  
Helena G. Asenjo ◽  
...  
Keyword(s):  
Transcription Initiation ◽  
Target Genes ◽  
Cpg Islands ◽  
Gene Promoters ◽  
Functional Communication ◽  
Regulatory Activity ◽  
Genetic Determinants ◽  
Developmental Genes ◽  
Developmental Gene Expression ◽  
Functional Relevance

ARTICLECpG islands (CGIs) represent a distinctive and widespread genetic feature of vertebrate genomes, being associated with ∼70% of all annotated gene promoters1. CGIs have been proposed to control transcription initiation by conferring nearby promoters with unique chromatin properties2–4. In addition, there are thousands of distal or orphan CGIs (oCGIs) whose functional relevance and mechanism of action are barely known5–7. Here we show that oCGIs are an essential component of poised enhancers (PEs)8, 9 that boost their long-range regulatory activity and dictate the responsiveness of their target genes. Using a CRISPR/Cas9 knock-in strategy in mESC, we introduced PEs with or without oCGIs within topological associating domains (TADs) harbouring genes with different types of promoters. By evaluating the chromatin, topological and regulatory properties of the engineered PEs, we uncover that, rather than increasing their local activation, oCGIs boost the physical and functional communication between PEs and distally located developmental genes. Furthermore, we demonstrate that developmental genes with CpG rich promoters are particularly responsive to PEs and that such responsiveness depends on the presence of oCGIs. Therefore, our work unveils a novel role for CGIs as genetic determinants of the compatibility between genes and enhancers, thus providing major insights into how developmental gene expression programs are deployed under both physiological and pathological conditions10–12.

scholarly journals BAP1 constrains pervasive H2AK119ub1 to control the transcriptional potential of the genome

2020 ◽  
Author(s):  
Nadezda A. Fursova ◽  
Anne H. Turberfield ◽  
Neil P. Blackledge ◽  
Emma L. Findlater ◽  
Anna Lastuvkova ◽  
...  
Keyword(s):  
Gene Expression ◽  
Histone Modifications ◽  
Transcription Initiation ◽  
Target Genes ◽  
Regulatory Elements ◽  
Polycomb Group ◽  
Gene Promoters ◽  
Histone H2a ◽  
Gene Regulatory Elements ◽  
Gene Regulatory

AbstractHistone-modifying systems play fundamental roles in gene regulation and the development of multicellular organisms. Histone modifications that are enriched at gene regulatory elements have been heavily studied, but the function of modifications that are found more broadly throughout the genome remains poorly understood. This is exemplified by histone H2A mono-ubiquitylation (H2AK119ub1) which is enriched at Polycomb-repressed gene promoters, but also covers the genome at lower levels. Here, using inducible genetic perturbations and quantitative genomics, we discover that the BAP1 deubiquitylase plays an essential role in constraining H2AK119ub1 throughout the genome. Removal of BAP1 leads to pervasive accumulation of H2AK119ub1, which causes widespread reductions in gene expression. We show that elevated H2AK119ub1 represses gene expression by counteracting transcription initiation from gene regulatory elements, causing reductions in transcription-associated histone modifications. Furthermore, failure to constrain pervasive H2AK119ub1 compromises Polycomb complex occupancy at a subset of Polycomb target genes leading to their derepression, therefore explaining the original genetic characterisation of BAP1 as a Polycomb group gene. Together, these observations reveal that the transcriptional potential of the genome can be modulated by regulating the levels of a pervasive histone modification, without the need for elaborate gene-specific targeting mechanisms.

scholarly journals ChIP-BIT2: a software tool to detect weak binding events using a Bayesian integration approach

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Xi Chen ◽  
Xu Shi ◽  
Andrew F. Neuwald ◽  
Leena Hilakivi-Clarke ◽  
Robert Clarke ◽  
...  
Keyword(s):  
Gene Expression ◽  
Binding Sites ◽  
Large Scale ◽  
Target Genes ◽  
Gene Expression Regulation ◽  
Software Tool ◽  
Gene Promoters ◽  
Weak Binding ◽  
Genomic Locations ◽  
And Control

Abstract Background ChIP-seq combines chromatin immunoprecipitation assays with sequencing and identifies genome-wide binding sites for DNA binding proteins. While many binding sites have strong ChIP-seq ‘peak’ observations and are well captured, there are still regions bound by proteins weakly, with a relatively low ChIP-seq signal enrichment. These weak binding sites, especially those at promoters and enhancers, are functionally important because they also regulate nearby gene expression. Yet, it remains a challenge to accurately identify weak binding sites in ChIP-seq data due to the ambiguity in differentiating these weak binding sites from the amplified background DNAs. Results ChIP-BIT2 (http://sourceforge.net/projects/chipbitc/) is a software package for ChIP-seq peak detection. ChIP-BIT2 employs a mixture model integrating protein and control ChIP-seq data and predicts strong or weak protein binding sites at promoters, enhancers, or other genomic locations. For binding sites at gene promoters, ChIP-BIT2 simultaneously predicts their target genes. ChIP-BIT2 has been validated on benchmark regions and tested using large-scale ENCODE ChIP-seq data, demonstrating its high accuracy and wide applicability. Conclusion ChIP-BIT2 is an efficient ChIP-seq peak caller. It provides a better lens to examine weak binding sites and can refine or extend the existing binding site collection, providing additional regulatory regions for decoding the mechanism of gene expression regulation.

scholarly journals Genome-wide targeting of the epigenetic regulatory protein CTCF to gene promoters by the transcription factor TFII-I

2015 ◽  
Vol 112 (7) ◽  
pp. E677-E686 ◽  
Author(s):  
Rodrigo Peña-Hernández ◽  
Maud Marques ◽  
Khalid Hilmi ◽  
Teijun Zhao ◽  
Amine Saad ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Rna Polymerase Ii ◽  
Transcription Initiation ◽  
Cellular Response ◽  
Target Genes ◽  
Regulatory Protein ◽  
Metabolic Stress ◽  
Ctcf Binding ◽  
Gene Promoters ◽  
The Impact

CCCTC-binding factor (CTCF) is a key regulator of nuclear chromatin structure and gene regulation. The impact of CTCF on transcriptional output is highly varied, ranging from repression to transcriptional pausing and transactivation. The multifunctional nature of CTCF may be directed solely through remodeling chromatin architecture. However, another hypothesis is that the multifunctional nature of CTCF is mediated, in part, through differential association with protein partners having unique functions. Consistent with this hypothesis, our mass spectrometry analyses of CTCF interacting partners reveal a previously undefined association with the transcription factor general transcription factor II-I (TFII-I). Biochemical fractionation of CTCF indicates that a distinct CTCF complex incorporating TFII-I is assembled on DNA. Unexpectedly, we found that the interaction between CTCF and TFII-I is essential for directing CTCF to the promoter proximal regulatory regions of target genes across the genome, particularly at genes involved in metabolism. At genes coregulated by CTCF and TFII-I, we find knockdown of TFII-I results in diminished CTCF binding, lack of cyclin-dependent kinase 8 (CDK8) recruitment, and an attenuation of RNA polymerase II phosphorylation at serine 5. Phenotypically, knockdown of TFII-I alters the cellular response to metabolic stress. Our data indicate that TFII-I directs CTCF binding to target genes, and in turn the two proteins cooperate to recruit CDK8 and enhance transcription initiation.

scholarly journals A Unified Architecture of Transcriptional Regulatory Elements

2015 ◽  
Author(s):  
Robin Andersson ◽  
Albin Sandelin ◽  
Charles G Danko
Keyword(s):  
Gene Expression ◽  
Histone Modifications ◽  
Transcription Initiation ◽  
Regulatory Elements ◽  
Functional Element ◽  
Gene Promoters ◽  
Single Class ◽  
Transcriptional Regulatory Elements ◽  
Transcriptional Regulatory ◽  
Transcriptional Output

Gene expression is precisely controlled in time and space through the integration of signals that act at gene promoters and gene-distal enhancers. Classically, promoters and enhancers are considered separate classes of regulatory elements, often distinguished by histone modifications. However, recent studies have revealed broad similarities between enhancers and promoters, blurring the distinction: active enhancers often initiate transcription, and some gene promoters have the potential of enhancing transcriptional output of other promoters. Here, we propose a model in which promoters and enhancers are considered a single class of functional element, with a unified architecture for transcription initiation. The context of interacting regulatory elements, and surrounding sequences, determine local transcriptional output as well as the enhancer and promoter activities of individual elements.

scholarly journals Rfx2 stabilizes Foxj1 binding at chromatin loops to enable multiciliated cell gene expression

2016 ◽  
Author(s):  
Ian K Quigley ◽  
Chris Kintner
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Transcription Factors ◽  
Target Genes ◽  
Gene Promoters ◽  
Topological Domains ◽  
Chromatin Loops ◽  
Organ Systems ◽  
Cilia Formation ◽  
Motile Cilia

AbstractCooperative transcription factor binding at cis-regulatory sites in the genome drives robust eukaryotic gene expression, and many such sites must be coordinated to produce coherent transcriptional programs. The transcriptional program leading to motile cilia formation requires members of the DNA-binding forkhead (Fox) and Rfx transcription factor families and these factors co-localize to cilia gene promoters, but it is not clear how many cilia genes are regulated by these two factors, whether these factors act directly or indirectly, or how these factors act with specificity in the context of a 3-dimensional genome. Here, we use genome-wide approaches to show that cilia genes reside at the boundaries of topological domains and that these areas have low enhancer density. We show that the transcription factors Foxj1 and Rfx2 binding occurs in the promoters of more cilia genes than other known cilia transcription factors and that while Rfx2 binds directly to promoters and enhancers equally, Foxj1 prefers direct binding to enhancers and is stabilized at promoters by Rfx2. Finally, we show that Rfx2 and Foxj1 lie at the anchor endpoints of chromatin loops, suggesting that target genes are activated when Foxj1 bound at distal sites is recruited via a loop created by Rfx2 binding at both sites. We speculate that the primary function of Rfx2 is to stabilize distal enhancers with proximal promoters by operating as a scaffolding factor, bringing key regulatory domains bound by Foxj1 into close physical proximity and enabling coordinated cilia gene expression.Author SummaryThe multiciliated cell extends hundreds of motile cilia to produce fluid flow in the airways and other organ systems. The formation of this specialized cell type requires the coordinated expression of hundreds of genes in order to produce all the protein parts motile cilia require. While a relatively small number of transcription factors has been identified that promote gene expression during multiciliate cell differentiation, it is not clear how they work together to coordinate the expression of genes required for multiple motile ciliation. Here, we show that two transcription factors known to drive cilia formation, Foxj1 and Rfx2, play complementary roles wherein Foxj1 activates target genes but tends not to bind near them in the genome, whereas Rfx2 can’t activate target genes by itself but instead acts as a scaffold by localizing Foxj1 to the proper targets. These results suggest not only a mechanism by which complex gene expression is coordinated in multiciliated cells, but also how transcriptional programs in general could be modular and deployed across different cellular contexts with the same basic promoter configuration.

scholarly journals Transcriptional enhancers and their communication with gene promoters

2021 ◽  
Author(s):  
Helen Ray-Jones ◽  
Mikhail Spivakov
Keyword(s):  
Gene Expression ◽  
Functional Genomics ◽  
Target Genes ◽  
Gene Control ◽  
Gene Promoters ◽  
Joint Effects ◽  
Transcriptional Enhancers ◽  
Quantitative Understanding ◽  
The Right ◽  
The Way

AbstractTranscriptional enhancers play a key role in the initiation and maintenance of gene expression programmes, particularly in metazoa. How these elements control their target genes in the right place and time is one of the most pertinent questions in functional genomics, with wide implications for most areas of biology. Here, we synthesise classic and recent evidence on the regulatory logic of enhancers, including the principles of enhancer organisation, factors that facilitate and delimit enhancer–promoter communication, and the joint effects of multiple enhancers. We show how modern approaches building on classic insights have begun to unravel the complexity of enhancer–promoter relationships, paving the way towards a quantitative understanding of gene control.

Androgen receptor: acting in the three-dimensional chromatin landscape of prostate cancer cells

2011 ◽  
Vol 5 (1) ◽  
Author(s):  
Harri Makkonen ◽  
Jorma J. Palvimo
Keyword(s):  
Prostate Cancer ◽  
Androgen Receptor ◽  
Cancer Cells ◽  
Binding Sites ◽  
Target Genes ◽  
Three Dimensional ◽  
Regulatory Elements ◽  
Gene Promoters ◽  
Loop Formation ◽  
Prostate Cancer Cells

AbstractAndrogen receptor (AR) acts as a hormone-controlled transcription factor that conveys the messages of both natural and synthetic androgens to the level of genes and gene programs. Defective AR signaling leads to a wide array of androgen insensitivity disorders, and deregulated AR function, in particular overexpression of AR, is involved in the growth and progression of prostate cancer. Classic models of AR action view AR-binding sites as upstream regulatory elements in gene promoters or their proximity. However, recent wider genomic screens indicate that AR target genes are commonly activated through very distal chromatin-binding sites. This highlights the importance of long-range chromatin regulation of transcription by the AR, shifting the focus from the linear gene models to three-dimensional models of AR target genes and gene programs. The capability of AR to regulate promoters from long distances in the chromatin is particularly important when evaluating the role of AR in the regulation of genes in malignant prostate cells that frequently show striking genomic aberrations, especially gene fusions. Therefore, in addition to the mechanisms of DNA loop formation between the enhancer bound ARs and the transcription apparatus at the target core promoter, the mechanisms insulating distally bound ARs from promiscuously making contacts and activating other than their normal target gene promoters are critical for proper physiological regulation and thus currently under intense investigation. This review discusses the current knowledge about the AR action in the context of gene aberrations and the three-dimensional chromatin landscape of prostate cancer cells.

scholarly journals Target Gene Specificity of E2F and Pocket Protein Family Members in Living Cells

2000 ◽  
Vol 20 (16) ◽  
pp. 5797-5807 ◽  
Author(s):  
Julie Wells ◽  
Kathryn E. Boyd ◽  
Christopher J. Fry ◽  
Stephanie M. Bartley ◽  
Peggy J. Farnham
Keyword(s):  
Cell Cycle ◽  
Target Gene ◽  
Target Genes ◽  
Protein Complexes ◽  
Current Model ◽  
Family Members ◽  
Living Cells ◽  
Gene Promoters ◽  
Pocket Protein ◽  
Protein Dna Interactions

ABSTRACT E2F-mediated transcription is thought to involve binding of an E2F-pocket protein complex to promoters in the G0 phase of the cell cycle and release of the pocket protein in late G1, followed by release of E2F in S phase. We have tested this model by monitoring protein-DNA interactions in living cells using a formaldehyde cross-linking and immunoprecipitation assay. We find that E2F target genes are bound by distinct E2F-pocket protein complexes which change as cells progress through the cell cycle. We also find that certain E2F target gene promoters are bound by pocket proteins when such promoters are transcriptionally active. Our data indicate that the current model applies only to certain E2F target genes and suggest that Rb family members may regulate transcription in both G0 and S phases. Finally, we find that a given promoter can be bound by one of several different E2F-pocket protein complexes at a given time in the cell cycle, suggesting that cell cycle-regulated transcription is a stochastic, not a predetermined, process.

scholarly journals Regulation of Poly(ADP-ribose) Polymerase-1-dependent Gene Expression through Promoter-directed Recruitment of a Nuclear NAD+ Synthase

2012 ◽  
Vol 287 (15) ◽  
pp. 12405-12416 ◽  
Author(s):  
Tong Zhang ◽  
Jhoanna G. Berrocal ◽  
Jie Yao ◽  
Michelle E. DuMond ◽  
Raga Krishnakumar ◽  
...  
Keyword(s):  
Enzymatic Activity ◽  
Target Gene ◽  
Target Genes ◽  
Enzymatic Activities ◽  
Gene Promoters ◽  
Protein Coding ◽  
Photon Excitation ◽  
Gene Sets ◽  
Cellular Compartments ◽  
Parp 1

NMNAT-1 and PARP-1, two key enzymes in the NAD+ metabolic pathway, localize to the nucleus where integration of their enzymatic activities has the potential to control a variety of nuclear processes. Using a variety of biochemical, molecular, cell-based, and genomic assays, we show that NMNAT-1 and PARP-1 physically and functionally interact at target gene promoters in MCF-7 cells. Specifically, we show that PARP-1 recruits NMNAT-1 to promoters where it produces NAD+ to support PARP-1 catalytic activity, but also enhances the enzymatic activity of PARP-1 independently of NAD+ production. Furthermore, using two-photon excitation microscopy, we show that NMNAT-1 catalyzes the production of NAD+ in a nuclear pool that may be distinct from other cellular compartments. In expression microarray experiments, depletion of NMNAT-1 or PARP-1 alters the expression of about 200 protein-coding genes each, with about 10% overlap between the two gene sets. NMNAT-1 enzymatic activity is required for PARP-1-dependent poly(ADP-ribosyl)ation at the promoters of commonly regulated target genes, as well as the expression of those target genes. Collectively, our studies link the enzymatic activities of NMNAT-1 and PARP-1 to the regulation of a set of common target genes through functional interactions at target gene promoters.

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