101
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Nonlinear control of transcription through enhancer-promoter interactions. Nature 2022; 604:571-577. [PMID: 35418676 PMCID: PMC9021019 DOI: 10.1038/s41586-022-04570-y] [Citation(s) in RCA: 159] [Impact Index Per Article: 79.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Accepted: 02/21/2022] [Indexed: 12/19/2022]
Abstract
Chromosome structure in mammals is thought to regulate transcription by modulating three-dimensional interactions between enhancers and promoters, notably through CTCF-mediated loops and topologically associating domains (TADs)1–4. However, how chromosome interactions are actually translated into transcriptional outputs remains unclear. Here, to address this question, we use an assay to position an enhancer at large numbers of densely spaced chromosomal locations relative to a fixed promoter, and measure promoter output and interactions within a genomic region with minimal regulatory and structural complexity. A quantitative analysis of hundreds of cell lines reveals that the transcriptional effect of an enhancer depends on its contact probabilities with the promoter through a nonlinear relationship. Mathematical modelling suggests that nonlinearity might arise from transient enhancer–promoter interactions being translated into slower promoter bursting dynamics in individual cells, therefore uncoupling the temporal dynamics of interactions from those of transcription. This uncovers a potential mechanism of how distal enhancers act from large genomic distances, and of how topologically associating domain boundaries block distal enhancers. Finally, we show that enhancer strength also determines absolute transcription levels as well as the sensitivity of a promoter to CTCF-mediated transcriptional insulation. Our measurements establish general principles for the context-dependent role of chromosome structure in long-range transcriptional regulation. The transcriptional effect of an enhancer depends on its contact probabilities with the promoter through a nonlinear relationship, and enhancer strength determines absolute transcription levels as well as the sensitivity of a promoter to CTCF-mediated transcriptional insulation.
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102
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Clow PA, Du M, Jillette N, Taghbalout A, Zhu JJ, Cheng AW. CRISPR-mediated multiplexed live cell imaging of nonrepetitive genomic loci with one guide RNA per locus. Nat Commun 2022; 13:1871. [PMID: 35387989 PMCID: PMC8987088 DOI: 10.1038/s41467-022-29343-z] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Accepted: 03/08/2022] [Indexed: 12/20/2022] Open
Abstract
Three-dimensional (3D) structures of the genome are dynamic, heterogeneous and functionally important. Live cell imaging has become the leading method for chromatin dynamics tracking. However, existing CRISPR- and TALE-based genomic labeling techniques have been hampered by laborious protocols and are ineffective in labeling non-repetitive sequences. Here, we report a versatile CRISPR/Casilio-based imaging method that allows for a nonrepetitive genomic locus to be labeled using one guide RNA. We construct Casilio dual-color probes to visualize the dynamic interactions of DNA elements in single live cells in the presence or absence of the cohesin subunit RAD21. Using a three-color palette, we track the dynamic 3D locations of multiple reference points along a chromatin loop. Casilio imaging reveals intercellular heterogeneity and interallelic asynchrony in chromatin interaction dynamics, underscoring the importance of studying genome structures in 4D.
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Affiliation(s)
- Patricia A Clow
- The Jackson Laboratory for Genomic Medicine, Farmington, CT, 06032, USA
| | - Menghan Du
- The Jackson Laboratory for Genomic Medicine, Farmington, CT, 06032, USA
- Department of Genetics and Genome Sciences, University of Connecticut Health Center, Farmington, CT, 06030, USA
| | | | - Aziz Taghbalout
- The Jackson Laboratory for Genomic Medicine, Farmington, CT, 06032, USA
| | - Jacqueline J Zhu
- The Jackson Laboratory for Genomic Medicine, Farmington, CT, 06032, USA.
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ, 85281, USA.
| | - Albert W Cheng
- The Jackson Laboratory for Genomic Medicine, Farmington, CT, 06032, USA.
- Department of Genetics and Genome Sciences, University of Connecticut Health Center, Farmington, CT, 06030, USA.
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ, 85281, USA.
- The Jackson Laboratory Cancer Center, Bar Harbor, ME, 04609, USA.
- Institute for Systems Genomics, University of Connecticut Health Center, Farmington, CT, 06030, USA.
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103
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Rinaldi L, Fettweis G, Kim S, Garcia DA, Fujiwara S, Johnson TA, Tettey TT, Ozbun L, Pegoraro G, Puglia M, Blagoev B, Upadhyaya A, Stavreva DA, Hager GL. The glucocorticoid receptor associates with the cohesin loader NIPBL to promote long-range gene regulation. SCIENCE ADVANCES 2022; 8:eabj8360. [PMID: 35353576 PMCID: PMC8967222 DOI: 10.1126/sciadv.abj8360] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 02/07/2022] [Indexed: 05/13/2023]
Abstract
The cohesin complex is central to chromatin looping, but mechanisms by which these long-range chromatin interactions are formed and persist remain unclear. We demonstrate that interactions between a transcription factor (TF) and the cohesin loader NIPBL regulate enhancer-dependent gene activity. Using mass spectrometry, genome mapping, and single-molecule tracking methods, we demonstrate that the glucocorticoid (GC) receptor (GR) interacts with NIPBL and the cohesin complex at the chromatin level, promoting loop extrusion and long-range gene regulation. Real-time single-molecule experiments show that loss of cohesin markedly diminishes the concentration of TF molecules at specific nuclear confinement sites, increasing TF local concentration and promoting gene regulation. Last, patient-derived acute myeloid leukemia cells harboring cohesin mutations exhibit a reduced response to GCs, suggesting that the GR-NIPBL-cohesin interaction is defective in these patients, resulting in poor response to GC treatment.
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Affiliation(s)
- Lorenzo Rinaldi
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Gregory Fettweis
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Sohyoung Kim
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - David A. Garcia
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
- Department of Physics, University of Maryland, College Park, MD 20742, USA
| | - Saori Fujiwara
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Thomas A. Johnson
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Theophilus T. Tettey
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Laurent Ozbun
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
- High-Throughput Imaging Facility (HiTIF), Center for Cancer Research (CCR), NCI/NIH, Bethesda, MD 20892, USA
| | - Gianluca Pegoraro
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
- High-Throughput Imaging Facility (HiTIF), Center for Cancer Research (CCR), NCI/NIH, Bethesda, MD 20892, USA
| | - Michele Puglia
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Blagoy Blagoev
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Arpita Upadhyaya
- Department of Physics, University of Maryland, College Park, MD 20742, USA
- Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742, USA
| | - Diana A. Stavreva
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Gordon L. Hager
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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104
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Herrmann JC, Beagrie RA, Hughes JR. Making connections: enhancers in cellular differentiation. Trends Genet 2022; 38:395-408. [PMID: 34753603 DOI: 10.1016/j.tig.2021.10.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 10/17/2021] [Accepted: 10/19/2021] [Indexed: 01/23/2023]
Abstract
Deciphering the process by which hundreds of distinct cell types emerge from a single zygote to form a complex multicellular organism remains one of the greatest challenges in biological research. Enhancers are known to be central to cell type-specific gene expression, yet many questions regarding how these genomic elements interact both temporally and spatially with other cis- and trans-acting factors to control transcriptional activity during differentiation and development remain unanswered. Here, we review our current understanding of the role of enhancers and their interactions in this context and highlight recent progress achieved with experimental methods of unprecedented resolution.
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Affiliation(s)
- Jennifer C Herrmann
- 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
| | - Robert A Beagrie
- MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Jim R Hughes
- 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.
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105
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Delker RK, Munce RH, Hu M, Mann RS. Fluorescent labeling of genomic loci in Drosophila imaginal discs with heterologous DNA-binding proteins. CELL REPORTS METHODS 2022; 2:100175. [PMID: 35475221 PMCID: PMC9017127 DOI: 10.1016/j.crmeth.2022.100175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 11/02/2021] [Accepted: 02/11/2022] [Indexed: 11/25/2022]
Abstract
Using the Drosophila melanogaster Hox gene Ultrabithorax (Ubx) as an example, we demonstrate the use of three heterologous DNA-binding protein systems-LacI/LacO, ParB1/ParS1, and ParB2/ParS2-to label genomic loci in imaginal discs with the insertion of a small DNA tag. We compare each system, considering the impact of labeling in genomic regions (1) inside versus outside of a transcribed gene body and (2) with varying chromatin accessibility. We demonstrate the value of this system by interrogating the relationship between gene expression level and enhancer-promoter distance, as well as inter-allelic distance at the Ubx locus. We find that the distance between an essential intronic cis-regulatory element, anterobithorax (abx), and the promoter does not vary with expression level. In contrast, inter-allelic distance correlates with Ubx expression level.
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Affiliation(s)
- Rebecca K. Delker
- Department of Biochemistry and Molecular Biophysics, Columbia University Irving Medical Center, New York, NY, USA
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
| | - Ross H. Munce
- Department of Biochemistry and Molecular Biophysics, Columbia University Irving Medical Center, New York, NY, USA
- Department of Genetics and Development, Columbia University Irving Medical Center, New York, NY, USA
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
| | - Michelle Hu
- Department of Biochemistry and Molecular Biophysics, Columbia University Irving Medical Center, New York, NY, USA
| | - Richard S. Mann
- Department of Biochemistry and Molecular Biophysics, Columbia University Irving Medical Center, New York, NY, USA
- Department of Neuroscience, Columbia University Irving Medical Center, New York, NY, USA
- Department of Systems Biology, Columbia University Irving Medical Center, New York, NY, USA
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
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106
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Epigenome editing and epigenetic gene regulation in disease phenotypes. KOREAN J CHEM ENG 2022; 39:1361-1367. [DOI: 10.1007/s11814-022-1076-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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107
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Abstract
The compaction of linear DNA into micrometer-sized nuclear boundaries involves the establishment of specific three-dimensional (3D) DNA structures complexed with histone proteins that form chromatin. The resulting structures modulate essential nuclear processes such as transcription, replication, and repair to facilitate or impede their multi-step progression and these contribute to dynamic modification of the 3D-genome organization. It is generally accepted that protein–protein and protein–DNA interactions form the basis of 3D-genome organization. However, the constant generation of mechanical forces, torques, and other stresses produced by various proteins translocating along DNA could be playing a larger role in genome organization than currently appreciated. Clearly, a thorough understanding of the mechanical determinants imposed by DNA transactions on the 3D organization of the genome is required. We provide here an overview of our current knowledge and highlight the importance of DNA and chromatin mechanics in gene expression.
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Affiliation(s)
- Rajiv Kumar Jha
- Gene Regulation Section, Laboratory of Pathology, Nci/nih, Bethesda, MD USA
| | - David Levens
- Gene Regulation Section, Laboratory of Pathology, Nci/nih, Bethesda, MD USA
| | - Fedor Kouzine
- Gene Regulation Section, Laboratory of Pathology, Nci/nih, Bethesda, MD USA
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108
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Molecular architecture of enhancer–promoter interaction. Curr Opin Cell Biol 2022; 74:62-70. [DOI: 10.1016/j.ceb.2022.01.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 12/29/2021] [Accepted: 01/10/2022] [Indexed: 12/26/2022]
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109
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Sood V, Misteli T. The stochastic nature of genome organization and function. Curr Opin Genet Dev 2022; 72:45-52. [PMID: 34808408 PMCID: PMC9014486 DOI: 10.1016/j.gde.2021.10.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 10/11/2021] [Accepted: 10/29/2021] [Indexed: 02/03/2023]
Abstract
Genomes have complex three-dimensional structures. High-resolution population-based biochemical studies over the last decade have painted a mostly static picture of the genome characterized by universal organizational features, such as chromatin domains and compartments. Yet, when analyzed at the single cell level, these architectural elements are highly variable. The heterogeneity in genome organization is in line with the inherent stochasticity of transcription that shows high variation between individual cells. We highlight recent findings on single-cell variability in genome organization and describe a framework for how the stochastic nature of chromatin organization may relate to transcription dynamics.
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Affiliation(s)
- Varun Sood
- National Cancer Institute, NIH, Bethesda, MD 20892, United States.
| | - Tom Misteli
- National Cancer Institute, NIH, Bethesda, MD 20892, United States.
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110
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Shvedunova M, Akhtar A. Modulation of cellular processes by histone and non-histone protein acetylation. Nat Rev Mol Cell Biol 2022; 23:329-349. [PMID: 35042977 DOI: 10.1038/s41580-021-00441-y] [Citation(s) in RCA: 267] [Impact Index Per Article: 133.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/25/2021] [Indexed: 12/12/2022]
Abstract
Lysine acetylation is a widespread and versatile protein post-translational modification. Lysine acetyltransferases and lysine deacetylases catalyse the addition or removal, respectively, of acetyl groups at both histone and non-histone targets. In this Review, we discuss several features of acetylation and deacetylation, including their diversity of targets, rapid turnover, exquisite sensitivity to the concentrations of the cofactors acetyl-CoA, acyl-CoA and NAD+, and tight interplay with metabolism. Histone acetylation and non-histone protein acetylation influence a myriad of cellular and physiological processes, including transcription, phase separation, autophagy, mitosis, differentiation and neural function. The activity of lysine acetyltransferases and lysine deacetylases can, in turn, be regulated by metabolic states, diet and specific small molecules. Histone acetylation has also recently been shown to mediate cellular memory. These features enable acetylation to integrate the cellular state with transcriptional output and cell-fate decisions.
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Affiliation(s)
- Maria Shvedunova
- Department of Chromatin Regulation, Max Planck Institute of Immunobiology and Epigenetics, Freiburg im Breisgau, Germany
| | - Asifa Akhtar
- Department of Chromatin Regulation, Max Planck Institute of Immunobiology and Epigenetics, Freiburg im Breisgau, Germany.
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111
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Okada H, Saga Y. Repurposing of the enhancer-promoter communication underlies the compensation of Mesp2 by Mesp1. PLoS Genet 2022; 18:e1010000. [PMID: 35025872 PMCID: PMC8791502 DOI: 10.1371/journal.pgen.1010000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 01/26/2022] [Accepted: 12/17/2021] [Indexed: 11/25/2022] Open
Abstract
Organisms are inherently equipped with buffering systems against genetic perturbations. Genetic compensation, the compensatory response by upregulating another gene or genes, is one such buffering mechanism. Recently, a well-conserved compensatory mechanism was proposed: transcriptional adaptation of homologs under the nonsense-mediated mRNA decay pathways. However, this model cannot explain the onset of all compensatory events. We report a novel genetic compensation mechanism operating over the Mesp gene locus. Mesp1 and Mesp2 are paralogs located adjacently in the genome. Mesp2 loss is partially rescued by Mesp1 upregulation in the presomitic mesoderm (PSM). Using a cultured PSM induction system, we reproduced the compensatory response in vitro and found that the Mesp2-enhancer is required to promote Mesp1. We revealed that the Mesp2-enhancer directly interacts with the Mesp1 promoter, thereby upregulating Mesp1 expression upon the loss of Mesp2. Of note, this interaction is established by genomic arrangement upon PSM development independently of Mesp2 disruption. We propose that the repurposing of this established enhancer-promoter communication is the mechanism underlying this compensatory response for the upregulation of the adjacent gene. Genetic compensation, the compensatory response by upregulating another gene or genes, is one of the inherent mechanisms against gene disruption to confer cellular fitness. However, the regulatory mechanisms are largely unknown. Nonsense-mediated mutant mRNA degradation was recently proposed as a conserved mechanism across species to upregulate homologous genes to compensate for a disrupted gene, but this cannot explain compensation events with no mutant mRNA. This study investigated the compensation mechanism operating over adjacent paralogs, Mesp1 and Mesp2, in the genome. Mesp genes encode essential transcription factors in the presomitic mesoderm for development. In general, an enhancer is considered to activate a target gene when it physically interacts with the target. The communication of the Mesp2-enhancer with the Mesp1 promoter is established upon differentiation of the presomitic mesoderm, but this communication activates Mesp1 only when Mesp2 is disrupted, leading to compensation. We revealed a novel compensation mechanism depending on the repurposing of this enhancer-promoter communication by gene disruption. Our study also provides new insight into transcriptional regulation by providing the concept that an enhancer changes its target even among its physically interacting genes in a context-dependent manner.
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Affiliation(s)
- Hajime Okada
- Department of Gene Function and Phenomics, National Institute of Genetics, Mishima, Japan
| | - Yumiko Saga
- Department of Gene Function and Phenomics, National Institute of Genetics, Mishima, Japan
- Department of Genetics, School of Life Science, The Graduate University for Advised Studies (SOKENDAI), Mishima, Japan
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan
- * E-mail:
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112
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Transcriptional Regulation and Implications for Controlling Hox Gene Expression. J Dev Biol 2022; 10:jdb10010004. [PMID: 35076545 PMCID: PMC8788451 DOI: 10.3390/jdb10010004] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 01/04/2022] [Accepted: 01/06/2022] [Indexed: 02/06/2023] Open
Abstract
Hox genes play key roles in axial patterning and regulating the regional identity of cells and tissues in a wide variety of animals from invertebrates to vertebrates. Nested domains of Hox expression generate a combinatorial code that provides a molecular framework for specifying the properties of tissues along the A–P axis. Hence, it is important to understand the regulatory mechanisms that coordinately control the precise patterns of the transcription of clustered Hox genes required for their roles in development. New insights are emerging about the dynamics and molecular mechanisms governing transcriptional regulation, and there is interest in understanding how these may play a role in contributing to the regulation of the expression of the clustered Hox genes. In this review, we summarize some of the recent findings, ideas and emerging mechanisms underlying the regulation of transcription in general and consider how they may be relevant to understanding the transcriptional regulation of Hox genes.
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113
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Steindel M, Orsine de Almeida I, Strawbridge S, Chernova V, Holcman D, Ponjavic A, Basu S. Studying the Dynamics of Chromatin-Binding Proteins in Mammalian Cells Using Single-Molecule Localization Microscopy. Methods Mol Biol 2022; 2476:209-247. [PMID: 35635707 DOI: 10.1007/978-1-0716-2221-6_16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Single-molecule localization microscopy (SMLM) allows the super-resolved imaging of proteins within mammalian nuclei at spatial resolutions comparable to that of a nucleosome itself (~20 nm). The technique is therefore well suited to the study of chromatin structure. Fixed-cell SMLM has already allowed temporal "snapshots" of how proteins are arranged on chromatin within mammalian nuclei. In this chapter, we focus on how recent developments, for example in selective plane illumination, 3D SMLM, and protein labeling, have led to a range of live-cell SMLM studies. We describe how to carry out single-particle tracking (SPT) of single proteins and, by analyzing their diffusion parameters, how to determine whether proteins interact with chromatin, diffuse freely, or do both. We can study the numbers of proteins that interact with chromatin and also determine their residence time on chromatin. We can determine whether these proteins form functional clusters within the nucleus as well as whether they form specific nuclear structures.
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Affiliation(s)
- Maike Steindel
- Wellcome-MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge, UK
| | | | - Stanley Strawbridge
- Wellcome-MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge, UK
| | - Valentyna Chernova
- Wellcome-MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge, UK
| | - David Holcman
- Group of Computational Biology and Applied Mathematics, Institute of Biology, Ecole Normale Supérieure, Paris, France
| | - Aleks Ponjavic
- School of Physics and Astronomy and School of Food Science and Nutrition, University of Leeds, Leeds, UK.
| | - Srinjan Basu
- Wellcome-MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge, UK.
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114
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Sabaté T, Zimmer C, Bertrand E. Versatile CRISPR-Based Method for Site-Specific Insertion of Repeat Arrays to Visualize Chromatin Loci in Living Cells. Methods Mol Biol 2022; 2532:275-290. [PMID: 35867254 DOI: 10.1007/978-1-0716-2497-5_13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Hi-C and related sequencing-based techniques have brought a detailed understanding of the 3D genome architecture and the discovery of novel structures such as topologically associating domains (TADs) and chromatin loops, which emerge from cohesin-mediated DNA extrusion. However, these techniques require cell fixation, which precludes assessment of chromatin structure dynamics, and are generally restricted to population averages, thus masking cell-to-cell heterogeneity. By contrast, live-cell imaging allows to characterize and quantify the temporal dynamics of chromatin, potentially including TADs and loops in single cells. Specific chromatin loci can be visualized at high temporal and spatial resolution by inserting a repeat array from bacterial operator sequences bound by fluorescent tags. Using two different types of repeats allows to tag both anchors of a loop in different colors, thus enabling to track them separately even when they are in close vicinity. Here, we describe a versatile cloning method for generating many repeat array repair cassettes in parallel and inserting them by CRISPR-Cas9 into the human genome. This method should be instrumental to studying chromatin loop dynamics in single human cells.
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Affiliation(s)
- Thomas Sabaté
- Imaging and Modeling Unit, Institut Pasteur, UMR 3691 CNRS, IP CNRS, Paris, France.
- IGH, University of Montpellier, CNRS, Montpellier, France.
- Sorbonne Université, Collège Doctoral, Paris, France.
| | - Christophe Zimmer
- Imaging and Modeling Unit, Institut Pasteur, UMR 3691 CNRS, IP CNRS, Paris, France
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115
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Maresca M, Liu NQ, de Wit E. Acute Protein Depletion Strategies to Functionally Dissect the 3D Genome. Methods Mol Biol 2022; 2532:311-331. [PMID: 35867256 DOI: 10.1007/978-1-0716-2497-5_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The organization of the genome inside the nucleus facilitates many nuclear processes. Because the nuclear genome is highly dynamic and often regulated by essential proteins, rapid depletion strategies are necessary to perform loss-of-function analyses. Fortunately, in recent years, various methods have been developed to manipulate the cellular levels of a protein directly and acutely. Here, we describe different methods that have been developed to rapidly deplete proteins from cells, with a focus on auxin inducible degron and dTAG methods, as these are most commonly used in 3D genome organization studies. We outline best practices for designing a knockin strategy, as well as generation and validation of knockin cell lines. Acute depletion strategies have been transformative for the study of the 3D genome and will be important tools for delineating the processes and factors that determine organization of the genome inside the nucleus.
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Affiliation(s)
- Michela Maresca
- Division Gene Regulation, Oncode Institute, Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Ning Qing Liu
- Division Gene Regulation, Oncode Institute, Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Elzo de Wit
- Division Gene Regulation, Oncode Institute, Netherlands Cancer Institute, Amsterdam, The Netherlands.
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116
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Karr JP, Ferrie JJ, Tjian R, Darzacq X. The transcription factor activity gradient (TAG) model: contemplating a contact-independent mechanism for enhancer-promoter communication. Genes Dev 2022; 36:7-16. [PMID: 34969825 PMCID: PMC8763055 DOI: 10.1101/gad.349160.121] [Citation(s) in RCA: 68] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
How distal cis-regulatory elements (e.g., enhancers) communicate with promoters remains an unresolved question of fundamental importance. Although transcription factors and cofactors are known to mediate this communication, the mechanism by which diffusible molecules relay regulatory information from one position to another along the chromosome is a biophysical puzzle-one that needs to be revisited in light of recent data that cannot easily fit into previous solutions. Here we propose a new model that diverges from the textbook enhancer-promoter looping paradigm and offer a synthesis of the literature to make a case for its plausibility, focusing on the coactivator p300.
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Affiliation(s)
- Jonathan P Karr
- University of California at Berkeley, Berkeley, California 94720, USA
| | - John J Ferrie
- University of California at Berkeley, Berkeley, California 94720, USA
- Howard Hughes Medical Institute, Berkeley, California 94720, USA
| | - Robert Tjian
- University of California at Berkeley, Berkeley, California 94720, USA
- Howard Hughes Medical Institute, Berkeley, California 94720, USA
| | - Xavier Darzacq
- University of California at Berkeley, Berkeley, California 94720, USA
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117
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Wurmser A, Basu S. Enhancer-Promoter Communication: It's Not Just About Contact. Front Mol Biosci 2022; 9:867303. [PMID: 35517868 PMCID: PMC9061983 DOI: 10.3389/fmolb.2022.867303] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 03/24/2022] [Indexed: 11/13/2022] Open
Abstract
Cis-regulatory elements such as enhancers can be located even a million base pairs away from their cognate promoter and yet modulate gene transcription. Indeed, the 3D organisation of chromatin enables the establishment of long-range enhancer-promoter communication. The observation of long-range enhancer-promoter chromatin loops at active genes originally led to a model in which enhancers and promoters form physical contacts between each other to control transcription. Yet, recent microscopy data has challenged this prevailing activity-by-contact model of enhancer-promoter communication in transcriptional activation. Live single-cell imaging approaches do not systematically reveal a correlation between enhancer-proximity and transcriptional activation. We therefore discuss the need to move from a static to a dynamic view of enhancer-promoter relationships. We highlight recent studies that not only reveal considerable chromatin movement in specific cell types, but suggest links between chromatin compaction, chromatin movement and transcription. We describe the interplay between enhancer-promoter proximity within the context of biomolecular condensates and the need to understand how condensate microenvironments influence the chromatin binding kinetics of proteins that bind at cis-regulatory elements to activate transcription. Finally, given the complex multi-scale interplay between regulatory proteins, enhancer-promoter proximity and movement, we propose the need to integrate information from complementary single-cell next-generation sequencing and live-cell imaging approaches to derive unified 3D theoretical models of enhancer-promoter communication that are ultimately predictive of transcriptional output and cell fate. In time, improved models will shed light on how tissues grow and diseases emerge.
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Affiliation(s)
- Annabelle Wurmser
- Wellcome-MRC Cambridge Stem Cell Institute, Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Srinjan Basu
- Wellcome-MRC Cambridge Stem Cell Institute, Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom.,Department of Physiology, Development, and Neuroscience, University of Cambridge, Cambridge, United Kingdom
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118
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Spatial organization of chromosomes leads to heterogeneous chromatin motion and drives the liquid- or gel-like dynamical behavior of chromatin. Genome Res 2021; 32:28-43. [PMID: 34963660 PMCID: PMC8744683 DOI: 10.1101/gr.275827.121] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 12/02/2021] [Indexed: 11/25/2022]
Abstract
Chromosome organization and dynamics are involved in regulating many fundamental processes such as gene transcription and DNA repair. Experiments unveiled that chromatin motion is highly heterogeneous inside cell nuclei, ranging from a liquid-like, mobile state to a gel-like, rigid regime. Using polymer modeling, we investigate how these different physical states and dynamical heterogeneities may emerge from the same structural mechanisms. We found that the formation of topologically associating domains (TADs) is a key driver of chromatin motion heterogeneity. In particular, we showed that the local degree of compaction of the TAD regulates the transition from a weakly compact, fluid state of chromatin to a more compact, gel state exhibiting anomalous diffusion and coherent motion. Our work provides a comprehensive study of chromosome dynamics and a unified view of chromatin motion enabling interpretation of the wide variety of dynamical behaviors observed experimentally across different biological conditions, suggesting that the "liquid" or "solid" state of chromatin are in fact two sides of the same coin.
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119
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Laverre A, Tannier E, Necsulea A. Long-range promoter-enhancer contacts are conserved during evolution and contribute to gene expression robustness. Genome Res 2021; 32:280-296. [PMID: 34930799 PMCID: PMC8805723 DOI: 10.1101/gr.275901.121] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 12/16/2021] [Indexed: 11/25/2022]
Abstract
Gene expression is regulated through complex molecular interactions, involving cis-acting elements that can be situated far away from their target genes. Data on long-range contacts between promoters and regulatory elements are rapidly accumulating. However, it remains unclear how these regulatory relationships evolve and how they contribute to the establishment of robust gene expression profiles. Here, we address these questions by comparing genome-wide maps of promoter-centered chromatin contacts in mouse and human. We show that there is significant evolutionary conservation of cis-regulatory landscapes, indicating that selective pressures act to preserve not only regulatory element sequences but also their chromatin contacts with target genes. The extent of evolutionary conservation is remarkable for long-range promoter–enhancer contacts, illustrating how the structure of regulatory landscapes constrains large-scale genome evolution. We show that the evolution of cis-regulatory landscapes, measured in terms of distal element sequences, synteny, or contacts with target genes, is significantly associated with gene expression evolution.
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Affiliation(s)
- Alexandre Laverre
- Université de Lyon, Université Claude Bernard Lyon 1, CNRS, Laboratoire de Biométrie et Biologie Evolutive
| | - Eric Tannier
- Université de Lyon, Université Claude Bernard Lyon 1, CNRS, Laboratoire de Biométrie et Biologie Evolutive, Centre de recherche Inria de Lyon
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120
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Olfactory receptor choice: a case study for gene regulation in a multi-enhancer system. Curr Opin Genet Dev 2021; 72:101-109. [PMID: 34896807 DOI: 10.1016/j.gde.2021.11.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 10/25/2021] [Accepted: 11/11/2021] [Indexed: 12/14/2022]
Abstract
The mammalian genome possesses >2000 olfactory receptor (OR) alleles regulated by 63 known OR-Enhancer elements, yet each olfactory sensory neuron (OSN) expresses only a single OR allele. Choreographed changes to OSN nuclear architecture are evidently necessary for OR expression. Additionally, the insulated organization of OR-enhancers around an OR allele is a hallmark of the chosen OR. However, the biology guiding OR choice itself is unclear. Innovations in single-cell and biophysics-based analysis of nuclear architecture are revising previous models of the nucleus to include its dynamic and probabilistic nature. In this review, we ground current knowledge of OR gene regulation in these emerging theories to speculate on mechanisms that may give rise to diverse and singular OR expression.
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121
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Athmane N, Williamson I, Boyle S, Biddie SC, Bickmore WA. MUC4 is not expressed in cell lines used for live cell imaging. Wellcome Open Res 2021; 6:265. [PMID: 34796278 PMCID: PMC8567686 DOI: 10.12688/wellcomeopenres.17229.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/17/2021] [Indexed: 11/20/2022] Open
Abstract
Background: The ability to visualise specific mammalian gene loci in living cells is important for understanding the dynamic processes linked to transcription. However, some of the tools used to target mammalian genes for live cell imaging, such as dCas9, have been reported to themselves impede processes linked to transcription. The
MUC4 gene is a popular target for live cell imaging studies due to the repetitive nature of sequences within some exons of this gene. Methods: We set out to compare the impact of dCas9 and TALE-based imaging tools on
MUC4 expression, including in human cell lines previously reported as expressing
MUC4. Results:
We were unable to detect
MUC4 mRNA in these cell lines. Moreover, analysis of publicly available data for histone modifications associated with transcription, and data for transcription itself, indicate that neither
MUC4, nor any of the mucin gene family are significantly expressed in the cell lines where
dCas9 targeting has been reported to repress
MUC4 and
MUC1 expression, or in the cell lines where dCas13 has been used to report
MUC4 RNA detection in live cells. Conclusions:
Methods for visualising specific gene loci and gene transcripts in live human cells are very challenging. Our data suggest that care should be given to the choice of the most appropriate cell lines for these analyses and that orthogonal methods of assaying gene expression be carefully compared.
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Affiliation(s)
- Naouel Athmane
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh, Scotland, EH42XU, UK
| | - Iain Williamson
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh, Scotland, EH42XU, UK
| | - Shelagh Boyle
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh, Scotland, EH42XU, UK
| | - Simon C Biddie
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh, Scotland, EH42XU, UK
| | - Wendy A Bickmore
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh, Scotland, EH42XU, UK
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122
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Athmane N, Williamson I, Boyle S, Biddie SC, Bickmore WA. MUC4 is not expressed in cell lines used for live cell imaging. Wellcome Open Res 2021; 6:265. [PMID: 34796278 DOI: 10.12688/wellcomeopenres.17229.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/30/2021] [Indexed: 11/20/2022] Open
Abstract
Background: The ability to visualise specific mammalian gene loci in living cells is important for understanding the dynamic processes linked to transcription. However, some of the tools used to target mammalian genes for live cell imaging, such as dCas9, have been reported to themselves impede processes linked to transcription. The MUC4 gene is a popular target for live cell imaging studies due to the repetitive nature of sequences within some exons of this gene. Methods: We set out to compare the impact of dCas9 and TALE-based imaging tools on MUC4 expression, including in human cell lines previously reported as expressing MUC4. Results: We were unable to detect MUC4 mRNA in these cell lines. Moreover, analysis of publicly available data for histone modifications associated with transcription, and data for transcription itself, indicate that neither MUC4, nor any of the mucin gene family are significantly expressed in the cell lines where dCas9 targeting has been reported to repress MUC4 and MUC1 expression, or in the cell lines where dCas13 has been used to report MUC4 RNA detection in live cells. Conclusions: Methods for visualising specific gene loci and gene transcripts in live human cells are very challenging. Our data suggest that care should be given to the choice of the most appropriate cell lines for these analyses and that orthogonal methods of assaying gene expression be carefully compared.
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Affiliation(s)
- Naouel Athmane
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh, Scotland, EH42XU, UK
| | - Iain Williamson
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh, Scotland, EH42XU, UK
| | - Shelagh Boyle
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh, Scotland, EH42XU, UK
| | - Simon C Biddie
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh, Scotland, EH42XU, UK
| | - Wendy A Bickmore
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh, Scotland, EH42XU, UK
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123
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Abstract
To predict transcription, one needs a mechanistic understanding of how the numerous required transcription factors (TFs) explore the nuclear space to find their target genes, assemble, cooperate, and compete with one another. Advances in fluorescence microscopy have made it possible to visualize real-time TF dynamics in living cells, leading to two intriguing observations: first, most TFs contact chromatin only transiently; and second, TFs can assemble into clusters through their intrinsically disordered regions. These findings suggest that highly dynamic events and spatially structured nuclear microenvironments might play key roles in transcription regulation that are not yet fully understood. The emerging model is that while some promoters directly convert TF-binding events into on/off cycles of transcription, many others apply complex regulatory layers that ultimately lead to diverse phenotypic outputs. Cracking this kinetic code is an ongoing and challenging task that is made possible by combining innovative imaging approaches with biophysical models.
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Affiliation(s)
- Feiyue Lu
- Institute for Systems Genetics and Cell Biology Department, NYU School of Medicine, New York, New York 10016, USA
| | - Timothée Lionnet
- Institute for Systems Genetics and Cell Biology Department, NYU School of Medicine, New York, New York 10016, USA
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124
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Goel VY, Hansen AS. The macro and micro of chromosome conformation capture. WILEY INTERDISCIPLINARY REVIEWS. DEVELOPMENTAL BIOLOGY 2021; 10:e395. [PMID: 32987449 PMCID: PMC8236208 DOI: 10.1002/wdev.395] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 07/21/2020] [Accepted: 07/31/2020] [Indexed: 12/14/2022]
Abstract
The 3D organization of the genome facilitates gene regulation, replication, and repair, making it a key feature of genomic function and one that remains to be properly understood. Over the past two decades, a variety of chromosome conformation capture (3C) methods have delineated genome folding from megabase-scale compartments and topologically associating domains (TADs) down to kilobase-scale enhancer-promoter interactions. Understanding the functional role of each layer of genome organization is a gateway to understanding cell state, development, and disease. Here, we discuss the evolution of 3C-based technologies for mapping 3D genome organization. We focus on genomics methods and provide a historical account of the development from 3C to Hi-C. We also discuss ChIP-based techniques that focus on 3D genome organization mediated by specific proteins, capture-based methods that focus on particular regions or regulatory elements, 3C-orthogonal methods that do not rely on restriction digestion and proximity ligation, and methods for mapping the DNA-RNA and RNA-RNA interactomes. We consider the biological discoveries that have come from these methods, examine the mechanistic contributions of CTCF, cohesin, and loop extrusion to genomic folding, and detail the 3D genome field's current understanding of nuclear architecture. Finally, we give special consideration to Micro-C as an emerging frontier in chromosome conformation capture and discuss recent Micro-C findings uncovering fine-scale chromatin organization in unprecedented detail. This article is categorized under: Gene Expression and Transcriptional Hierarchies > Regulatory Mechanisms Gene Expression and Transcriptional Hierarchies > Gene Networks and Genomics.
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Affiliation(s)
- Viraat Y. Goel
- Department of Biological EngineeringMassachusetts Institute of TechnologyCambridgeMassachusettsUSA
| | - Anders S. Hansen
- Department of Biological EngineeringMassachusetts Institute of TechnologyCambridgeMassachusettsUSA
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125
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Ridnik M, Schoenfelder S, Gonen N. Cis-Regulatory Control of Mammalian Sex Determination. Sex Dev 2021; 15:317-334. [PMID: 34710870 PMCID: PMC8743899 DOI: 10.1159/000519244] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 08/10/2021] [Indexed: 11/19/2022] Open
Abstract
Sex determination is the process by which an initial bipotential gonad adopts either a testicular or ovarian cell fate. The inability to properly complete this process leads to a group of developmental disorders classified as disorders of sex development (DSD). To date, dozens of genes were shown to play roles in mammalian sex determination, and mutations in these genes can cause DSD in humans or gonadal sex reversal/dysfunction in mice. However, exome sequencing currently provides genetic diagnosis for only less than half of DSD patients. This points towards a major role for the non-coding genome during sex determination. In this review, we highlight recent advances in our understanding of non-coding, cis-acting gene regulatory elements and discuss how they may control transcriptional programmes that underpin sex determination in the context of the 3-dimensional folding of chromatin. As a paradigm, we focus on the Sox9 gene, a prominent pro-male factor and one of the most extensively studied genes in gonadal cell fate determination.
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Affiliation(s)
- Meshi Ridnik
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
- Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan, Israel
| | - Stefan Schoenfelder
- Epigenetics Programme, The Babraham Institute, Babraham Research Campus, Cambridge, United Kingdom
| | - Nitzan Gonen
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
- Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan, Israel
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126
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Abstract
Mammalian genomes have distinct levels of spatial organization and structure that have been hypothesized to play important roles in transcription regulation. Although much has been learned about these architectural features with ensemble techniques, single-cell studies are showing a new universal trend: Genomes are stochastic and dynamic at every level of organization. Stochastic gene expression, on the other hand, has been studied for years. In this review, we probe whether there is a causative link between the two phenomena. We specifically discuss the functionality of chromatin state, topologically associating domains (TADs), and enhancer biology in light of their stochastic nature and their specific roles in stochastic gene expression. We highlight persistent fundamental questions in this area of research.
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Affiliation(s)
- Christopher H Bohrer
- Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Daniel R Larson
- Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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127
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Ray-Jones H, Spivakov M. Transcriptional enhancers and their communication with gene promoters. Cell Mol Life Sci 2021; 78:6453-6485. [PMID: 34414474 PMCID: PMC8558291 DOI: 10.1007/s00018-021-03903-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 07/08/2021] [Accepted: 07/19/2021] [Indexed: 12/13/2022]
Abstract
Transcriptional 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.
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Affiliation(s)
- Helen Ray-Jones
- MRC London Institute of Medical Sciences, London, W12 0NN, UK
- Institute of Clinical Sciences, Faculty of Medicine, Imperial College, London, W12 0NN, UK
| | - Mikhail Spivakov
- MRC London Institute of Medical Sciences, London, W12 0NN, UK.
- Institute of Clinical Sciences, Faculty of Medicine, Imperial College, London, W12 0NN, UK.
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128
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Perea-Resa C, Wattendorf L, Marzouk S, Blower MD. Cohesin: behind dynamic genome topology and gene expression reprogramming. Trends Cell Biol 2021; 31:760-773. [PMID: 33766521 PMCID: PMC8364472 DOI: 10.1016/j.tcb.2021.03.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 02/23/2021] [Accepted: 03/04/2021] [Indexed: 01/01/2023]
Abstract
Beyond its originally discovered role tethering replicated sister chromatids, cohesin has emerged as a master regulator of gene expression. Recent advances in chromatin topology resolution and single-cell studies have revealed that cohesin has a pivotal role regulating highly dynamic chromatin interactions linked to transcription control. The dynamic association of cohesin with chromatin and its capacity to perform loop extrusion contribute to the heterogeneity of chromatin contacts. Additionally, different cohesin subcomplexes, with specific properties and regulation, control gene expression across the cell cycle and during developmental cell commitment. Here, we discuss the most recent literature in the field to highlight the role of cohesin in gene expression regulation during transcriptional shifts and its relationship with human diseases.
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Affiliation(s)
- Carlos Perea-Resa
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, USA.
| | - Lauren Wattendorf
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, USA
| | - Sammer Marzouk
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, USA
| | - Michael D Blower
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, USA.
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129
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Enhancers navigate the three-dimensional genome to direct cell fate decisions. Curr Opin Struct Biol 2021; 71:101-109. [PMID: 34280668 DOI: 10.1016/j.sbi.2021.06.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 05/31/2021] [Accepted: 06/07/2021] [Indexed: 01/05/2023]
Abstract
The activity and selectivity of transcriptional enhancers determine gene expression patterns that enable a zygote to become a complex organism. How enhancers convey regulatory information is a central conundrum in biology. Here, we discuss recent progress provided by rapidly evolving technologies in understanding enhancer-promoter interactions in the context of overall nuclear genome organization.
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130
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Xiao JY, Hafner A, Boettiger AN. How subtle changes in 3D structure can create large changes in transcription. eLife 2021; 10:e64320. [PMID: 34240703 PMCID: PMC8352591 DOI: 10.7554/elife.64320] [Citation(s) in RCA: 65] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Accepted: 06/25/2021] [Indexed: 12/17/2022] Open
Abstract
Animal genomes are organized into topologically associated domains (TADs). TADs are thought to contribute to gene regulation by facilitating enhancer-promoter (E-P) contacts within a TAD and preventing these contacts across TAD borders. However, the absolute difference in contact frequency across TAD boundaries is usually less than 2-fold, even though disruptions of TAD borders can change gene expression by 10-fold. Existing models fail to explain this hypersensitive response. Here, we propose a futile cycle model of enhancer-mediated regulation that can exhibit hypersensitivity through bistability and hysteresis. Consistent with recent experiments, this regulation does not exhibit strong correlation between E-P contact and promoter activity, even though regulation occurs through contact. Through mathematical analysis and stochastic simulation, we show that this system can create an illusion of E-P biochemical specificity and explain the importance of weak TAD boundaries. It also offers a mechanism to reconcile apparently contradictory results from recent global TAD disruption with local TAD boundary deletion experiments. Together, these analyses advance our understanding of cis-regulatory contacts in controlling gene expression and suggest new experimental directions.
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Affiliation(s)
| | - Antonina Hafner
- Department of Developmental Biology, Stanford UniversityStanfordUnited States
| | - Alistair N Boettiger
- Program in Biophysics, Stanford UniversityStanfordUnited States
- Department of Developmental Biology, Stanford UniversityStanfordUnited States
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131
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Monfils K, Barakat TS. Models behind the mystery of establishing enhancer-promoter interactions. Eur J Cell Biol 2021; 100:151170. [PMID: 34246183 DOI: 10.1016/j.ejcb.2021.151170] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 06/30/2021] [Accepted: 07/02/2021] [Indexed: 10/20/2022] Open
Abstract
Enhancers and promoters are transcriptional regulatory elements whose facilitated interactions increase gene expression. Enhancer DNA sequences can be located far away from the promoter sequences that they regulate. Currently, the mechanism facilitating the establishment of enhancer-promoter interactions remains unclear. However, mutations causing errors in these interactions have been linked to cancer and disease, further conveying the need to understand the full mechanism. This review discusses multiple models that have been proposed to describe how enhancers go the distance to interact with promoters. Evidence supporting loop formation models is reviewed in addition to more complex hypotheses involving aspects of 3D chromatin organization and phase separation.
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Affiliation(s)
- Kathryn Monfils
- Department of Clinical Genetics, Erasmus MC University Medical Center, PO Box 2040, 3000 CA, Rotterdam, the Netherlands
| | - Tahsin Stefan Barakat
- Department of Clinical Genetics, Erasmus MC University Medical Center, PO Box 2040, 3000 CA, Rotterdam, the Netherlands.
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132
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Xie L, Liu Z. Single-cell imaging of genome organization and dynamics. Mol Syst Biol 2021; 17:e9653. [PMID: 34232558 PMCID: PMC8262488 DOI: 10.15252/msb.20209653] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 04/13/2021] [Accepted: 04/23/2021] [Indexed: 12/28/2022] Open
Abstract
Probing the architecture, mechanism, and dynamics of genome folding is fundamental to our understanding of genome function in homeostasis and disease. Most chromosome conformation capture studies dissect the genome architecture with population- and time-averaged snapshots and thus have limited capabilities to reveal 3D nuclear organization and dynamics at the single-cell level. Here, we discuss emerging imaging techniques ranging from light microscopy to electron microscopy that enable investigation of genome folding and dynamics at high spatial and temporal resolution. Results from these studies complement genomic data, unveiling principles underlying the spatial arrangement of the genome and its potential functional links to diverse biological activities in the nucleus.
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Affiliation(s)
- Liangqi Xie
- Janelia Research CampusHoward Hughes Medical InstituteAshburnVAUSA
| | - Zhe Liu
- Janelia Research CampusHoward Hughes Medical InstituteAshburnVAUSA
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133
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Huang H, Zhu Q, Jussila A, Han Y, Bintu B, Kern C, Conte M, Zhang Y, Bianco S, Chiariello AM, Yu M, Hu R, Tastemel M, Juric I, Hu M, Nicodemi M, Zhuang X, Ren B. CTCF mediates dosage- and sequence-context-dependent transcriptional insulation by forming local chromatin domains. Nat Genet 2021; 53:1064-1074. [PMID: 34002095 PMCID: PMC8853952 DOI: 10.1038/s41588-021-00863-6] [Citation(s) in RCA: 87] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 04/02/2021] [Indexed: 02/03/2023]
Abstract
Insulators play a critical role in spatiotemporal gene regulation in animals. The evolutionarily conserved CCCTC-binding factor (CTCF) is required for insulator function in mammals, but not all of its binding sites act as insulators. Here we explore the sequence requirements of CTCF-mediated transcriptional insulation using a sensitive insulator reporter in mouse embryonic stem cells. We find that insulation potency depends on the number of CTCF-binding sites in tandem. Furthermore, CTCF-mediated insulation is dependent on upstream flanking sequences at its binding sites. CTCF-binding sites at topologically associating domain boundaries are more likely to function as insulators than those outside topologically associating domain boundaries, independently of binding strength. We demonstrate that insulators form local chromatin domain boundaries and weaken enhancer-promoter contacts. Taken together, our results provide genetic, molecular and structural evidence connecting chromatin topology to the action of insulators in the mammalian genome.
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Affiliation(s)
- Hui Huang
- Ludwig Institute for Cancer Research, La Jolla, California 92093, USA, University of California, San Diego, Biomedical Sciences Graduate Program, La Jolla, California 92093, USA
| | - Quan Zhu
- University of California, San Diego School of Medicine, Department of Cellular and Molecular Medicine, Center for Epigenomics, 9500 Gilman Drive, La Jolla, CA 92093-0653, USA
| | - Adam Jussila
- Ludwig Institute for Cancer Research, La Jolla, California 92093, USA, Bioinformatics and Systems Biology Graduate Program, University of California San Diego, La Jolla, CA 92093, USA
| | - Yuanyuan Han
- University of California, San Diego School of Medicine, Department of Cellular and Molecular Medicine, Center for Epigenomics, 9500 Gilman Drive, La Jolla, CA 92093-0653, USA
| | - Bogdan Bintu
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology and Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | - Colin Kern
- University of California, San Diego School of Medicine, Department of Cellular and Molecular Medicine, Center for Epigenomics, 9500 Gilman Drive, La Jolla, CA 92093-0653, USA
| | - Mattia Conte
- Dipartimento di Fisica, Università di Napoli Federico II, and INFN Napoli, Complesso di Monte Sant’Angelo, Naples, Italy
| | - Yanxiao Zhang
- Ludwig Institute for Cancer Research, La Jolla, California 92093, USA
| | - Simona Bianco
- Dipartimento di Fisica, Università di Napoli Federico II, and INFN Napoli, Complesso di Monte Sant’Angelo, Naples, Italy
| | - Andrea M. Chiariello
- Dipartimento di Fisica, Università di Napoli Federico II, and INFN Napoli, Complesso di Monte Sant’Angelo, Naples, Italy
| | - Miao Yu
- Ludwig Institute for Cancer Research, La Jolla, California 92093, USA
| | - Rong Hu
- Ludwig Institute for Cancer Research, La Jolla, California 92093, USA
| | - Melodi Tastemel
- University of California, San Diego School of Medicine, Department of Cellular and Molecular Medicine, 9500 Gilman Drive, La Jolla, CA 92093-0653, USA
| | - Ivan Juric
- Department of Quantitative Health Sciences, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA
| | - Ming Hu
- Department of Quantitative Health Sciences, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA
| | - Mario Nicodemi
- Dipartimento di Fisica, Università di Napoli Federico II, and INFN Napoli, Complesso di Monte Sant’Angelo, Naples, Italy, Berlin Institute for Medical Systems Biology, Max Delbrück Centre (MDC) for Molecular Medicine, Berlin, Germany., Berlin Institute of Health (BIH), Berlin, Germany
| | - Xiaowei Zhuang
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology and Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | - Bing Ren
- Ludwig Institute for Cancer Research, La Jolla, California 92093, USA, University of California, San Diego School of Medicine, Department of Cellular and Molecular Medicine, Center for Epigenomics, 9500 Gilman Drive, La Jolla, CA 92093-0653, USA, University of California, San Diego School of Medicine, Department of Cellular and Molecular Medicine, 9500 Gilman Drive, La Jolla, CA 92093-0653, USA, University of California, San Diego School of Medicine, Institute of Genomic Medicine, and Moores Cancer Center, 9500 Gilman Drive, La Jolla, CA 92093-0653, USA,Correspondence:
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134
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Li J, Pertsinidis A. New insights into promoter-enhancer communication mechanisms revealed by dynamic single-molecule imaging. Biochem Soc Trans 2021; 49:1299-1309. [PMID: 34060610 PMCID: PMC8325597 DOI: 10.1042/bst20200963] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 04/29/2021] [Accepted: 04/30/2021] [Indexed: 01/10/2023]
Abstract
Establishing cell-type-specific gene expression programs relies on the action of distal enhancers, cis-regulatory elements that can activate target genes over large genomic distances - up to Mega-bases away. How distal enhancers physically relay regulatory information to target promoters has remained a mystery. Here, we review the latest developments and insights into promoter-enhancer communication mechanisms revealed by live-cell, real-time single-molecule imaging approaches.
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Affiliation(s)
- Jieru Li
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, NY 10065, USA
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135
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Geng Y, Pertsinidis A. Simple and versatile imaging of genomic loci in live mammalian cells and early pre-implantation embryos using CAS-LiveFISH. Sci Rep 2021; 11:12220. [PMID: 34108610 PMCID: PMC8190065 DOI: 10.1038/s41598-021-91787-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 06/01/2021] [Indexed: 11/14/2022] Open
Abstract
Visualizing the 4D genome in live cells is essential for understanding its regulation. Programmable DNA-binding probes, such as fluorescent clustered regularly interspaced short palindromic repeats (CRISPR) and transcription activator-like effector (TALE) proteins have recently emerged as powerful tools for imaging specific genomic loci in live cells. However, many such systems rely on genetically-encoded components, often requiring multiple constructs that each must be separately optimized, thus limiting their use. Here we develop efficient and versatile systems, based on in vitro transcribed single-guide-RNAs (sgRNAs) and fluorescently-tagged recombinant, catalytically-inactivated Cas9 (dCas9) proteins. Controlled cell delivery of pre-assembled dCas9-sgRNA ribonucleoprotein (RNP) complexes enables robust genomic imaging in live cells and in early mouse embryos. We further demonstrate multiplex tagging of up to 3 genes, tracking detailed movements of chromatin segments and imaging spatial relationships between a distal enhancer and a target gene, with nanometer resolution in live cells. This simple and effective approach should facilitate visualizing chromatin dynamics and nuclear architecture in various living systems.
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Affiliation(s)
- Yongtao Geng
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
| | - Alexandros Pertsinidis
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA.
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136
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Rajpurkar AR, Mateo LJ, Murphy SE, Boettiger AN. Deep learning connects DNA traces to transcription to reveal predictive features beyond enhancer-promoter contact. Nat Commun 2021; 12:3423. [PMID: 34103507 PMCID: PMC8187657 DOI: 10.1038/s41467-021-23831-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 05/19/2021] [Indexed: 11/27/2022] Open
Abstract
Chromatin architecture plays an important role in gene regulation. Recent advances in super-resolution microscopy have made it possible to measure chromatin 3D structure and transcription in thousands of single cells. However, leveraging these complex data sets with a computationally unbiased method has been challenging. Here, we present a deep learning-based approach to better understand to what degree chromatin structure relates to transcriptional state of individual cells. Furthermore, we explore methods to "unpack the black box" to determine in an unbiased manner which structural features of chromatin regulation are most important for gene expression state. We apply this approach to an Optical Reconstruction of Chromatin Architecture dataset of the Bithorax gene cluster in Drosophila and show it outperforms previous contact-focused methods in predicting expression state from 3D structure. We find the structural information is distributed across the domain, overlapping and extending beyond domains identified by prior genetic analyses. Individual enhancer-promoter interactions are a minor contributor to predictions of activity.
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Affiliation(s)
- Aparna R Rajpurkar
- Department of Genetics, Stanford University, Stanford, CA, USA
- Department of Developmental Biology, Stanford University, Stanford, CA, USA
| | - Leslie J Mateo
- Department of Developmental Biology, Stanford University, Stanford, CA, USA
| | - Sedona E Murphy
- Department of Genetics, Stanford University, Stanford, CA, USA
- Department of Developmental Biology, Stanford University, Stanford, CA, USA
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137
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Agelopoulos M, Foutadakis S, Thanos D. The Causes and Consequences of Spatial Organization of the Genome in Regulation of Gene Expression. Front Immunol 2021; 12:682397. [PMID: 34149720 PMCID: PMC8212036 DOI: 10.3389/fimmu.2021.682397] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 05/18/2021] [Indexed: 01/05/2023] Open
Abstract
Regulation of gene expression in time, space and quantity is orchestrated by the functional interplay of cis-acting elements and trans-acting factors. Our current view postulates that transcription factors recognize enhancer DNA and read the transcriptional regulatory code by cooperative DNA binding to specific DNA motifs, thus instructing the recruitment of transcriptional regulatory complexes forming a plethora of higher-ordered multi-protein-DNA and protein-protein complexes. Here, we reviewed the formation of multi-dimensional chromatin assemblies implicated in gene expression with emphasis on the regulatory role of enhancer hubs as coordinators of stochastic gene expression. Enhancer hubs contain many interacting regulatory elements and represent a remarkably dynamic and heterogeneous network of multivalent interactions. A functional consequence of such complex interaction networks could be that individual enhancers function synergistically to ensure coordination, tight control and robustness in regulation of expression of spatially connected genes. In this review, we discuss fundamental paradigms of such inter- and intra- chromosomal associations both in the context of immune-related genes and beyond.
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Affiliation(s)
| | | | - Dimitris Thanos
- Biomedical Research Foundation, Academy of Athens, Athens, Greece
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138
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Aboelnour E, Bonev B. Decoding the organization, dynamics, and function of the 4D genome. Dev Cell 2021; 56:1562-1573. [PMID: 33984271 DOI: 10.1016/j.devcel.2021.04.023] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 02/15/2021] [Accepted: 04/21/2021] [Indexed: 11/15/2022]
Abstract
Understanding how complex cell-fate decisions emerge at the molecular level is a key challenge in developmental biology. Despite remarkable progress in decoding the contribution of the linear epigenome, how spatial genome architecture functionally informs changes in gene expression remains unclear. In this review, we discuss recent insights in elucidating the molecular landscape of genome folding, emphasizing the multilayered nature of the 3D genome, its importance for gene regulation, and its spatiotemporal dynamics. Finally, we discuss how these new concepts and emergent technologies will enable us to address some of the outstanding questions in development and disease.
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Affiliation(s)
- Erin Aboelnour
- Helmholtz Pioneer Campus, Helmholtz Zentrum München, 85764 Neuherberg, Germany
| | - Boyan Bonev
- Helmholtz Pioneer Campus, Helmholtz Zentrum München, 85764 Neuherberg, Germany; Biomedical Center (BMC), Faculty of Medicine, LMU Munich, Germany.
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139
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Grosveld F, van Staalduinen J, Stadhouders R. Transcriptional Regulation by (Super)Enhancers: From Discovery to Mechanisms. Annu Rev Genomics Hum Genet 2021; 22:127-146. [PMID: 33951408 DOI: 10.1146/annurev-genom-122220-093818] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Accurate control of gene expression in the right cell at the right moment is of fundamental importance to animal development and homeostasis. At the heart of gene regulation lie the enhancers, a class of gene regulatory elements that ensures precise spatiotemporal activation of gene transcription. Mammalian genomes are littered with enhancers, which are frequently organized in cooperative clusters such as locus control regions and superenhancers. Here, we discuss our current knowledge of enhancer biology, including an overview of the discovery of the various enhancer subsets and the mechanistic models used to explain their gene regulatory function.
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Affiliation(s)
- Frank Grosveld
- Department of Cell Biology, Erasmus MC, 3000 CA Rotterdam, The Netherlands; ,
| | | | - Ralph Stadhouders
- Department of Cell Biology, Erasmus MC, 3000 CA Rotterdam, The Netherlands; , .,Department of Pulmonary Medicine, Erasmus MC, 3000 CA Rotterdam, The Netherlands
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140
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Zhang D, Lam J, Blobel GA. Engineering three-dimensional genome folding. Nat Genet 2021; 53:602-611. [PMID: 33958782 DOI: 10.1038/s41588-021-00860-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 03/29/2021] [Indexed: 02/02/2023]
Abstract
Animal genomes are partitioned and folded at various scales that contribute distinctly to nuclear processes. While structural features have been disrupted either globally or at select loci in loss-of-function studies, gain-of-function studies that probe the role of genome architecture have lagged behind. Here we examine recent advances in experimentally creating chromatin loops, contact domains, boundaries and compartments. Furthermore, we explore parallels between this emerging theme and natural evolution of mammalian genomes with increasing architectural complexity. Finally, we provide a perspective on how insights arising from recent gain-of-function studies may inform future endeavors toward engineering the three-dimensional genome.
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Affiliation(s)
- Di Zhang
- Division of Hematology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA.,Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Jessica Lam
- Division of Hematology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA.,Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Gerd A Blobel
- Division of Hematology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA. .,Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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141
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Abstract
Shadow enhancers are seemingly redundant transcriptional cis-regulatory elements that regulate the same gene and drive overlapping expression patterns. Recent studies have shown that shadow enhancers are remarkably abundant and control most developmental gene expression in both invertebrates and vertebrates, including mammals. Shadow enhancers might provide an important mechanism for buffering gene expression against mutations in non-coding regulatory regions of genes implicated in human disease. Technological advances in genome editing and live imaging have shed light on how shadow enhancers establish precise gene expression patterns and confer phenotypic robustness. Shadow enhancers can interact in complex ways and may also help to drive the formation of transcriptional hubs within the nucleus. Despite their apparent redundancy, the prevalence and evolutionary conservation of shadow enhancers underscore their key role in emerging metazoan gene regulatory networks.
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142
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Panigrahi A, O'Malley BW. Mechanisms of enhancer action: the known and the unknown. Genome Biol 2021; 22:108. [PMID: 33858480 PMCID: PMC8051032 DOI: 10.1186/s13059-021-02322-1] [Citation(s) in RCA: 128] [Impact Index Per Article: 42.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 03/23/2021] [Indexed: 12/13/2022] Open
Abstract
Differential gene expression mechanisms ensure cellular differentiation and plasticity to shape ontogenetic and phylogenetic diversity of cell types. A key regulator of differential gene expression programs are the enhancers, the gene-distal cis-regulatory sequences that govern spatiotemporal and quantitative expression dynamics of target genes. Enhancers are widely believed to physically contact the target promoters to effect transcriptional activation. However, our understanding of the full complement of regulatory proteins and the definitive mechanics of enhancer action is incomplete. Here, we review recent findings to present some emerging concepts on enhancer action and also outline a set of outstanding questions.
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Affiliation(s)
- Anil Panigrahi
- Department of Molecular and Cellular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA
| | - Bert W O'Malley
- Department of Molecular and Cellular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA.
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143
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Abstract
How transcriptional enhancers function to activate distant genes has been the subject of lively investigation for decades. "Enhancers, gene regulation, and genome organization" was the subject of a virtual meeting held November 16-17, 2020, under sponsorship of the National Cancer Institute (NCI), the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), and the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) at the National Institutes of Health (NIH). The goal of the meeting was to advance an understanding of how transcriptional enhancers function within the framework of the folded genome as we understand it, emphasizing how levels of organization may influence each other and may contribute to the spatiotemporal specification of transcription. Here we focus on broad questions about enhancer function that remain unsettled and that we anticipate will be central to work in this field going forward. Perforce, we cover contributions of only some speakers and apologize to other contributors in vital areas that we could not include because of space constraints.
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Affiliation(s)
- Ann Dean
- Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda Maryland 20892, USA
| | - Daniel R Larson
- Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Vittorio Sartorelli
- Laboratory of Muscle Stem Cells and Gene Regulation, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
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144
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Espinola SM, Götz M, Bellec M, Messina O, Fiche JB, Houbron C, Dejean M, Reim I, Cardozo Gizzi AM, Lagha M, Nollmann M. Cis-regulatory chromatin loops arise before TADs and gene activation, and are independent of cell fate during early Drosophila development. Nat Genet 2021; 53:477-486. [PMID: 33795867 DOI: 10.1038/s41588-021-00816-z] [Citation(s) in RCA: 81] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 02/09/2021] [Indexed: 12/15/2022]
Abstract
Acquisition of cell fate is thought to rely on the specific interaction of remote cis-regulatory modules (CRMs), for example, enhancers and target promoters. However, the precise interplay between chromatin structure and gene expression is still unclear, particularly within multicellular developing organisms. In the present study, we employ Hi-M, a single-cell spatial genomics approach, to detect CRM-promoter looping interactions within topologically associating domains (TADs) during early Drosophila development. By comparing cis-regulatory loops in alternate cell types, we show that physical proximity does not necessarily instruct transcriptional states. Moreover, multi-way analyses reveal that multiple CRMs spatially coalesce to form hubs. Loops and CRM hubs are established early during development, before the emergence of TADs. Moreover, CRM hubs are formed, in part, via the action of the pioneer transcription factor Zelda and precede transcriptional activation. Our approach provides insight into the role of CRM-promoter interactions in defining transcriptional states, as well as distinct cell types.
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Affiliation(s)
- Sergio Martin Espinola
- Centre de Biologie Structurale, CNRS UMR 5048, INSERM U1054, Univ Montpellier, Montpellier, France
| | - Markus Götz
- Centre de Biologie Structurale, CNRS UMR 5048, INSERM U1054, Univ Montpellier, Montpellier, France
| | | | - Olivier Messina
- Centre de Biologie Structurale, CNRS UMR 5048, INSERM U1054, Univ Montpellier, Montpellier, France.,IGMM, CNRS, Univ Montpellier, Montpellier, France
| | - Jean-Bernard Fiche
- Centre de Biologie Structurale, CNRS UMR 5048, INSERM U1054, Univ Montpellier, Montpellier, France
| | - Christophe Houbron
- Centre de Biologie Structurale, CNRS UMR 5048, INSERM U1054, Univ Montpellier, Montpellier, France
| | | | - Ingolf Reim
- Department of Biology, Friedrich-Alexander University of Erlangen-Nürnberg, Erlangen, Germany
| | - Andrés M Cardozo Gizzi
- Centro de Investigación en Medicina Traslacional Severo Amuchastegui, Instituto Universitario de Ciencias Biomédicas de Córdoba, Consejo Nacional de Investigaciones Científicas y Técnicas, Córdoba, Argentina
| | - Mounia Lagha
- IGMM, CNRS, Univ Montpellier, Montpellier, France.
| | - Marcelo Nollmann
- Centre de Biologie Structurale, CNRS UMR 5048, INSERM U1054, Univ Montpellier, Montpellier, France.
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145
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The nuclear to cytoplasmic ratio directly regulates zygotic transcription in Drosophila through multiple modalities. Proc Natl Acad Sci U S A 2021; 118:2010210118. [PMID: 33790005 DOI: 10.1073/pnas.2010210118] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Early embryos must rapidly generate large numbers of cells to form an organism. Many species accomplish this through a series of rapid, reductive, and transcriptionally silent cleavage divisions. Previous work has demonstrated that the number of divisions before both cell cycle elongation and zygotic genome activation (ZGA) is regulated by the ratio of nuclear content to cytoplasm (N/C). To understand how the N/C ratio affects the timing of ZGA, we directly assayed the behavior of several previously identified N/C ratio-dependent genes using the MS2-MCP reporter system in living Drosophila embryos with altered ploidy and cell cycle durations. For every gene that we examined, we found that nascent RNA output per cycle is delayed in haploid embryos. Moreover, we found that the N/C ratio influences transcription through three overlapping modes of action. For some genes (knirps, fushi tarazu, and snail), the effect of ploidy can be primarily attributed to changes in cell cycle duration. However, additional N/C ratio-mediated mechanisms contribute significantly to transcription delays for other genes. For giant and bottleneck, the kinetics of transcription activation are significantly disrupted in haploids, while for frühstart and Krüppel, the N/C ratio controls the probability of transcription initiation. Our data demonstrate that the regulatory elements of N/C ratio-dependent genes respond directly to the N/C ratio through multiple modes of regulation.
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146
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Understanding transcription across scales: From base pairs to chromosomes. Mol Cell 2021; 81:1601-1616. [PMID: 33770487 DOI: 10.1016/j.molcel.2021.03.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 02/23/2021] [Accepted: 02/26/2021] [Indexed: 02/07/2023]
Abstract
The influence of genome organization on transcription is central to our understanding of cell type specification. Higher-order genome organization is established through short- and long-range DNA interactions. Coordination of these interactions, from single atoms to entire chromosomes, plays a fundamental role in transcriptional control of gene expression. Loss of this coupling can result in disease. Analysis of transcriptional regulation typically involves disparate experimental approaches, from structural studies that define angstrom-level interactions to cell-biological and genomic approaches that assess mesoscale relationships. Thus, to fully understand the mechanisms that regulate gene expression, it is critical to integrate the findings gained across these distinct size scales. In this review, I illustrate fundamental ways in which cells regulate transcription in the context of genome organization.
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147
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Agrawal P, Rao S. Super-Enhancers and CTCF in Early Embryonic Cell Fate Decisions. Front Cell Dev Biol 2021; 9:653669. [PMID: 33842482 PMCID: PMC8027350 DOI: 10.3389/fcell.2021.653669] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 02/18/2021] [Indexed: 12/04/2022] Open
Abstract
Cell fate decisions are the backbone of many developmental and disease processes. In early mammalian development, precise gene expression changes underly the rapid division of a single cell that leads to the embryo and are critically dependent on autonomous cell changes in gene expression. To understand how these lineage specifications events are mediated, scientists have had to look past protein coding genes to the cis regulatory elements (CREs), including enhancers and insulators, that modulate gene expression. One class of enhancers, termed super-enhancers, is highly active and cell-type specific, implying their critical role in modulating cell-type specific gene expression. Deletion or mutations within these CREs adversely affect gene expression and development and can cause disease. In this mini-review we discuss recent studies describing the potential roles of two CREs, enhancers and binding sites for CTCF, in early mammalian development.
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Affiliation(s)
- Puja Agrawal
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, WI, United States
- Versiti Blood Research Institute, Milwaukee, WI, United States
| | - Sridhar Rao
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, WI, United States
- Versiti Blood Research Institute, Milwaukee, WI, United States
- Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, United States
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148
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Zhang M, Yang C, Tasan I, Zhao H. Expanding the Potential of Mammalian Genome Engineering via Targeted DNA Integration. ACS Synth Biol 2021; 10:429-446. [PMID: 33596056 DOI: 10.1021/acssynbio.0c00576] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Inserting custom designed DNA sequences into the mammalian genome plays an essential role in synthetic biology. In particular, the ability to introduce foreign DNA in a site-specific manner offers numerous advantages over random DNA integration. In this review, we focus on two mechanistically distinct systems that have been widely adopted for targeted DNA insertion in mammalian cells, the CRISPR/Cas9 system and site-specific recombinases. The CRISPR/Cas9 system has revolutionized the genome engineering field thanks to its high programmability and ease of use. However, due to its dependence on linearized DNA donor and endogenous cellular pathways to repair the induced double-strand break, CRISPR/Cas9-mediated DNA insertion still faces limitations such as small insert size, and undesired editing outcomes via error-prone repair pathways. In contrast, site-specific recombinases, in particular the Serine integrases, demonstrate large-cargo capability and no dependence on cellular repair pathways for DNA integration. Here we first describe recent advances in improving the overall efficacy of CRISPR/Cas9-based methods for DNA insertion. Moreover, we highlight the advantages of site-specific recombinases over CRISPR/Cas9 in the context of targeted DNA integration, with a special focus on the recent development of programmable recombinases. We conclude by discussing the importance of protein engineering to further expand the current toolkit for targeted DNA insertion in mammalian cells.
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Affiliation(s)
- Meng Zhang
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Che Yang
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Ipek Tasan
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Huimin Zhao
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
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149
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Kubo N, Ishii H, Xiong X, Bianco S, Meitinger F, Hu R, Hocker JD, Conte M, Gorkin D, Yu M, Li B, Dixon JR, Hu M, Nicodemi M, Zhao H, Ren B. Promoter-proximal CTCF binding promotes distal enhancer-dependent gene activation. Nat Struct Mol Biol 2021; 28:152-161. [PMID: 33398174 PMCID: PMC7913465 DOI: 10.1038/s41594-020-00539-5] [Citation(s) in RCA: 148] [Impact Index Per Article: 49.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 11/06/2020] [Indexed: 01/28/2023]
Abstract
The CCCTC-binding factor (CTCF) works together with the cohesin complex to drive the formation of chromatin loops and topologically associating domains, but its role in gene regulation has not been fully defined. Here, we investigated the effects of acute CTCF loss on chromatin architecture and transcriptional programs in mouse embryonic stem cells undergoing differentiation to neural precursor cells. We identified CTCF-dependent enhancer-promoter contacts genome-wide and found that they disproportionately affect genes that are bound by CTCF at the promoter and are dependent on long-distance enhancers. Disruption of promoter-proximal CTCF binding reduced both long-range enhancer-promoter contacts and transcription, which were restored by artificial tethering of CTCF to the promoter. Promoter-proximal CTCF binding is correlated with the transcription of over 2,000 genes across a diverse set of adult tissues. Taken together, the results of our study show that CTCF binding to promoters may promote long-distance enhancer-dependent transcription at specific genes in diverse cell types.
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Affiliation(s)
- Naoki Kubo
- Department of Cellular and Molecular Medicine, University of California San Diego School of Medicine, La Jolla, CA, USA
| | - Haruhiko Ishii
- Department of Cellular and Molecular Medicine, University of California San Diego School of Medicine, La Jolla, CA, USA
| | - Xiong Xiong
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Simona Bianco
- Department of Physics, University of Naples Federico II, and INFN Complesso di Monte Sant’Angelo, Naples, Italy
| | - Franz Meitinger
- Department of Cellular and Molecular Medicine, University of California San Diego School of Medicine, La Jolla, CA, USA
| | - Rong Hu
- Department of Cellular and Molecular Medicine, University of California San Diego School of Medicine, La Jolla, CA, USA
| | - James D. Hocker
- Department of Cellular and Molecular Medicine, University of California San Diego School of Medicine, La Jolla, CA, USA
| | - Mattia Conte
- Department of Physics, University of Naples Federico II, and INFN Complesso di Monte Sant’Angelo, Naples, Italy
| | - David Gorkin
- Department of Cellular and Molecular Medicine, Center for Epigenomics, University of California San Diego School of Medicine, La Jolla, CA, USA
| | - Miao Yu
- Department of Cellular and Molecular Medicine, University of California San Diego School of Medicine, La Jolla, CA, USA
| | - Bin Li
- Department of Cellular and Molecular Medicine, University of California San Diego School of Medicine, La Jolla, CA, USA
| | - Jesse R. Dixon
- Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Ming Hu
- Department of Quantitative Health Sciences, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH, USA
| | - Mario Nicodemi
- Department of Physics, University of Naples Federico II, and INFN Complesso di Monte Sant’Angelo, Naples, Italy
| | - Huimin Zhao
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA,Departments of Chemistry, Biochemistry, and Bioengineering, and Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Bing Ren
- Department of Cellular and Molecular Medicine, University of California San Diego School of Medicine, La Jolla, CA, USA,Department of Cellular and Molecular Medicine, Center for Epigenomics, University of California San Diego School of Medicine, La Jolla, CA, USA,Department of Cellular and Molecular Medicine, Moores Cancer Center and Institute of Genome Medicine, University of California San Diego School of Medicine, La Jolla, CA, USA,Correspondence to:
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Crump NT, Ballabio E, Godfrey L, Thorne R, Repapi E, Kerry J, Tapia M, Hua P, Lagerholm C, Filippakopoulos P, Davies JOJ, Milne TA. BET inhibition disrupts transcription but retains enhancer-promoter contact. Nat Commun 2021; 12:223. [PMID: 33431820 PMCID: PMC7801379 DOI: 10.1038/s41467-020-20400-z] [Citation(s) in RCA: 67] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2019] [Accepted: 12/01/2020] [Indexed: 12/13/2022] Open
Abstract
Enhancers are DNA sequences that enable complex temporal and tissue-specific regulation of genes in higher eukaryotes. Although it is not entirely clear how enhancer-promoter interactions can increase gene expression, this proximity has been observed in multiple systems at multiple loci and is thought to be essential for the maintenance of gene expression. Bromodomain and Extra-Terminal domain (BET) and Mediator proteins have been shown capable of forming phase condensates and are thought to be essential for super-enhancer function. Here, we show that targeting of cells with inhibitors of BET proteins or pharmacological degradation of BET protein Bromodomain-containing protein 4 (BRD4) has a strong impact on transcription but very little impact on enhancer-promoter interactions. Dissolving phase condensates reduces BRD4 and Mediator binding at enhancers and can also strongly affect gene transcription, without disrupting enhancer-promoter interactions. These results suggest that activation of transcription and maintenance of enhancer-promoter interactions are separable events. Our findings further indicate that enhancer-promoter interactions are not dependent on high levels of BRD4 and Mediator, and are likely maintained by a complex set of factors including additional activator complexes and, at some sites, CTCF and cohesin.
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Affiliation(s)
- Nicholas T Crump
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, NIHR Oxford Biomedical Research Centre Haematology Theme, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Erica Ballabio
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, NIHR Oxford Biomedical Research Centre Haematology Theme, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Laura Godfrey
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, NIHR Oxford Biomedical Research Centre Haematology Theme, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Ross Thorne
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, NIHR Oxford Biomedical Research Centre Haematology Theme, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Emmanouela Repapi
- MRC WIMM Centre for Computational Biology, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Jon Kerry
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, NIHR Oxford Biomedical Research Centre Haematology Theme, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Marta Tapia
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, NIHR Oxford Biomedical Research Centre Haematology Theme, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DS, UK
- The Finsen Laboratory, Rigshospitalet, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
- Biotech Research and Innovation Centre (BRIC), Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Peng Hua
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Christoffer Lagerholm
- Wolfson Imaging Centre Oxford, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Panagis Filippakopoulos
- Structural Genomics Consortium, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, OX3 7DQ, UK
| | - James O J Davies
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Thomas A Milne
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, NIHR Oxford Biomedical Research Centre Haematology Theme, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DS, UK.
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