Publications by authors named "Robert A Beagrie"

10 Publications

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Reactivation of a developmentally silenced embryonic globin gene.

Nat Commun 2021 07 21;12(1):4439. Epub 2021 Jul 21.

MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK.

The α- and β-globin loci harbor developmentally expressed genes, which are silenced throughout post-natal life. Reactivation of these genes may offer therapeutic approaches for the hemoglobinopathies, the most common single gene disorders. Here, we address mechanisms regulating the embryonically expressed α-like globin, termed ζ-globin. We show that in embryonic erythroid cells, the ζ-gene lies within a ~65 kb sub-TAD (topologically associating domain) of open, acetylated chromatin and interacts with the α-globin super-enhancer. By contrast, in adult erythroid cells, the ζ-gene is packaged within a small (~10 kb) sub-domain of hypoacetylated, facultative heterochromatin within the acetylated sub-TAD and that it no longer interacts with its enhancers. The ζ-gene can be partially re-activated by acetylation and inhibition of histone de-acetylases. In addition to suggesting therapies for severe α-thalassemia, these findings illustrate the general principles by which reactivation of developmental genes may rescue abnormalities arising from mutations in their adult paralogues.
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http://dx.doi.org/10.1038/s41467-021-24402-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8295333PMC
July 2021

Enhancers predominantly regulate gene expression during differentiation via transcription initiation.

Mol Cell 2021 03 3;81(5):983-997.e7. Epub 2021 Feb 3.

MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK; MRC WIMM Centre for Computational Biology, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK. Electronic address:

Gene transcription occurs via a cycle of linked events, including initiation, promoter-proximal pausing, and elongation of RNA polymerase II (Pol II). A key question is how transcriptional enhancers influence these events to control gene expression. Here, we present an approach that evaluates the level and change in promoter-proximal transcription (initiation and pausing) in the context of differential gene expression, genome-wide. This combinatorial approach shows that in primary cells, control of gene expression during differentiation is achieved predominantly via changes in transcription initiation rather than via release of Pol II pausing. Using genetically engineered mouse models, deleted for functionally validated enhancers of the α- and β-globin loci, we confirm that these elements regulate Pol II recruitment and/or initiation to modulate gene expression. Together, our data show that gene expression during differentiation is regulated predominantly at the level of initiation and that enhancers are key effectors of this process.
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http://dx.doi.org/10.1016/j.molcel.2021.01.002DOI Listing
March 2021

High-resolution targeted 3C interrogation of cis-regulatory element organization at genome-wide scale.

Nat Commun 2021 01 22;12(1):531. Epub 2021 Jan 22.

MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK.

Chromosome conformation capture (3C) provides an adaptable tool for studying diverse biological questions. Current 3C methods generally provide either low-resolution interaction profiles across the entire genome, or high-resolution interaction profiles at limited numbers of loci. Due to technical limitations, generation of reproducible high-resolution interaction profiles has not been achieved at genome-wide scale. Here, to overcome this barrier, we systematically test each step of 3C and report two improvements over current methods. We show that up to 30% of reporter events generated using the popular in situ 3C method arise from ligations between two individual nuclei, but this noise can be almost entirely eliminated by isolating intact nuclei after ligation. Using Nuclear-Titrated Capture-C, we generate reproducible high-resolution genome-wide 3C interaction profiles by targeting 8055 gene promoters in erythroid cells. By pairing high-resolution 3C interaction calls with nascent gene expression we interrogate the role of promoter hubs and super-enhancers in gene regulation.
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http://dx.doi.org/10.1038/s41467-020-20809-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7822813PMC
January 2021

The mouse alpha-globin cluster: a paradigm for studying genome regulation and organization.

Curr Opin Genet Dev 2021 04 19;67:18-24. Epub 2020 Nov 19.

Laboratory of Gene Regulation, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK. Electronic address:

The mammalian globin gene clusters provide a paradigm for studying the relationship between genome structure and function. As blood stem cells undergo lineage specification and differentiation to form red blood cells, the chromatin structure and expression of the α-globin cluster change. The gradual activation of the α-globin genes in well-defined cell populations has enabled investigation of the structural and functional roles of its enhancers, promoters and boundary elements. Recent studies of gene regulatory processes involving these elements at the mouse α-globin cluster have brought new insights into the general principles underlying the three-dimensional structure of the genome and its relationship to gene expression throughout time.
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http://dx.doi.org/10.1016/j.gde.2020.10.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8100094PMC
April 2021

Hypoxia Induces Transcriptional and Translational Downregulation of the Type I IFN Pathway in Multiple Cancer Cell Types.

Cancer Res 2020 12 28;80(23):5245-5256. Epub 2020 Oct 28.

Department of Medical Oncology, Molecular Oncology Laboratories, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom.

Hypoxia is a common phenomenon in solid tumors and is strongly linked to hallmarks of cancer. Recent evidence has shown that hypoxia promotes local immune suppression. Type I IFN supports cytotoxic T lymphocytes by stimulating the maturation of dendritic cells and enhancing their capacity to process and present antigens. However, little is known about the relationship between hypoxia and the type I IFN pathway, which comprises the sensing of double-stranded RNA and DNA (dsRNA/dsDNA) followed by IFNα/β secretion and transcriptional activation of IFN-stimulated genes (ISG). In this study, we determined the effects of hypoxia on the type I IFN pathway in breast cancer and the mechanisms involved. In cancer cell lines and xenograft models, mRNA and protein expressions of the type I IFN pathway were downregulated under hypoxic conditions. This pathway was suppressed at each level of signaling, from the dsRNA sensors RIG-I and MDA5, the adaptor MAVS, transcription factors IRF3, IRF7, and STAT1, and several ISG including RIG-I, IRF7, STAT1, and ADAR-p150. Importantly, IFN secretion was reduced under hypoxic conditions. HIF1α- and HIF2α-mediated regulation of gene expression did not explain most of the effects. However, ATAC-seq data revealed in hypoxia that peaks with STAT1 and IRF3 motifs had decreased accessibility. Collectively, these results indicate that hypoxia leads to an overall downregulation of the type I IFN pathway due to repressed transcription and lower chromatin accessibility in an HIF1/2α-independent manner, which could contribute to immunosuppression in hypoxic tumors. SIGNIFICANCE: These findings characterize a new mechanism of immunosuppression by hypoxia via downregulation of the type I IFN pathway and its autocrine/paracrine effects on tumor growth.
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http://dx.doi.org/10.1158/0008-5472.CAN-19-2306DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7611234PMC
December 2020

Dynamics of the 4D genome during in vivo lineage specification and differentiation.

Nat Commun 2020 06 1;11(1):2722. Epub 2020 Jun 1.

MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK.

Mammalian gene expression patterns are controlled by regulatory elements, which interact within topologically associating domains (TADs). The relationship between activation of regulatory elements, formation of structural chromatin interactions and gene expression during development is unclear. Here, we present Tiled-C, a low-input chromosome conformation capture (3C) technique. We use this approach to study chromatin architecture at high spatial and temporal resolution through in vivo mouse erythroid differentiation. Integrated analysis of chromatin accessibility and single-cell expression data shows that regulatory elements gradually become accessible within pre-existing TADs during early differentiation. This is followed by structural re-organization within the TAD and formation of specific contacts between enhancers and promoters. Our high-resolution data show that these enhancer-promoter interactions are not established prior to gene expression, but formed gradually during differentiation, concomitant with progressive upregulation of gene activity. Together, these results provide new insight into the close, interdependent relationship between chromatin architecture and gene regulation during development.
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http://dx.doi.org/10.1038/s41467-020-16598-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7264236PMC
June 2020

Cell cycle: Continuous chromatin changes.

Nature 2017 07;547(7661):34-35

Max Delbrück Center for Molecular Medicine, Berlin Institute for Medical Systems Biology, Berlin 13125, Germany.

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http://dx.doi.org/10.1038/547034aDOI Listing
July 2017

Complex multi-enhancer contacts captured by genome architecture mapping.

Nature 2017 03 8;543(7646):519-524. Epub 2017 Mar 8.

Epigenetic Regulation and Chromatin Architecture Group, Berlin Institute for Medical Systems Biology, Max-Delbrück Centre for Molecular Medicine, Robert-Rössle Straße, Berlin-Buch 13125, Germany.

The organization of the genome in the nucleus and the interactions of genes with their regulatory elements are key features of transcriptional control and their disruption can cause disease. Here we report a genome-wide method, genome architecture mapping (GAM), for measuring chromatin contacts and other features of three-dimensional chromatin topology on the basis of sequencing DNA from a large collection of thin nuclear sections. We apply GAM to mouse embryonic stem cells and identify enrichment for specific interactions between active genes and enhancers across very large genomic distances using a mathematical model termed SLICE (statistical inference of co-segregation). GAM also reveals an abundance of three-way contacts across the genome, especially between regions that are highly transcribed or contain super-enhancers, providing a level of insight into genome architecture that, owing to the technical limitations of current technologies, has previously remained unattainable. Furthermore, GAM highlights a role for gene-expression-specific contacts in organizing the genome in mammalian nuclei.
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http://dx.doi.org/10.1038/nature21411DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5366070PMC
March 2017

Examining Topological Domain Influence on Enhancer Function.

Dev Cell 2016 12;39(5):523-524

Epigenetic Regulation and Chromatin Architecture Group, Berlin Institute for Medical Systems Biology, Max-Delbrück Centre for Molecular Medicine, Robert-Rössle Strasse, Berlin-Buch 13092, Germany. Electronic address:

Enhancers regulate the expression of target genes across large genomic distances, but it is unclear how recently discovered topological domains affect this regulation. Reporting in this issue of Developmental Cell, Symmons et al. (2016) show that the endogenous Shh topological domain promotes functional interactions between Shh and its remote enhancer.
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http://dx.doi.org/10.1016/j.devcel.2016.11.011DOI Listing
December 2016

Gene activation by metazoan enhancers: Diverse mechanisms stimulate distinct steps of transcription.

Bioessays 2016 09 25;38(9):881-93. Epub 2016 Jul 25.

Epigenetic Regulation and Chromatin Architecture Group, Berlin Institute for Medical Systems Biology, Max-Delbrück Centre for Molecular Medicine, Berlin-Buch, Germany.

Enhancers can stimulate transcription by a number of different mechanisms which control different stages of the transcription cycle of their target genes, from recruitment of the transcription machinery to elongation by RNA polymerase. These mechanisms may not be mutually exclusive, as a single enhancer may act through different pathways by binding multiple transcription factors. Multiple enhancers may also work together to regulate transcription of a shared target gene. Most of the evidence supporting different enhancer mechanisms comes from the study of single genes, but new high-throughput experimental frameworks offer the opportunity to integrate and generalize disparate mechanisms identified at single genes. This effort is especially important if we are to fully understand how sequence variation within enhancers contributes to human disease.
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http://dx.doi.org/10.1002/bies.201600032DOI Listing
September 2016
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