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Yang JH, Hansen AS. Enhancer selectivity in space and time: from enhancer-promoter interactions to promoter activation. Nat Rev Mol Cell Biol 2024:10.1038/s41580-024-00710-6. [PMID: 38413840 DOI: 10.1038/s41580-024-00710-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/30/2024] [Indexed: 02/29/2024]
Abstract
The primary regulators of metazoan gene expression are enhancers, originally functionally defined as DNA sequences that can activate transcription at promoters in an orientation-independent and distance-independent manner. Despite being crucial for gene regulation in animals, what mechanisms underlie enhancer selectivity for promoters, and more fundamentally, how enhancers interact with promoters and activate transcription, remain poorly understood. In this Review, we first discuss current models of enhancer-promoter interactions in space and time and how enhancers affect transcription activation. Next, we discuss different mechanisms that mediate enhancer selectivity, including repression, biochemical compatibility and regulation of 3D genome structure. Through 3D polymer simulations, we illustrate how the ability of 3D genome folding mechanisms to mediate enhancer selectivity strongly varies for different enhancer-promoter interaction mechanisms. Finally, we discuss how recent technical advances may provide new insights into mechanisms of enhancer-promoter interactions and how technical biases in methods such as Hi-C and Micro-C and imaging techniques may affect their interpretation.
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Affiliation(s)
- Jin H Yang
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- Gene Regulation Observatory, Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Koch Institute for Integrative Cancer Research, Cambridge, MA, USA
| | - Anders S Hansen
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
- Gene Regulation Observatory, Broad Institute of MIT and Harvard, Cambridge, MA, USA.
- Koch Institute for Integrative Cancer Research, Cambridge, MA, USA.
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2
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Santarelli P, Rosti V, Vivo M, Lanzuolo C. Chromatin organization of muscle stem cell. Curr Top Dev Biol 2024; 158:375-406. [PMID: 38670713 DOI: 10.1016/bs.ctdb.2024.01.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/28/2024]
Abstract
The proper functioning of skeletal muscles is essential throughout life. A crucial crosstalk between the environment and several cellular mechanisms allows striated muscles to perform successfully. Notably, the skeletal muscle tissue reacts to an injury producing a completely functioning tissue. The muscle's robust regenerative capacity relies on the fine coordination between muscle stem cells (MuSCs or "satellite cells") and their specific microenvironment that dictates stem cells' activation, differentiation, and self-renewal. Critical for the muscle stem cell pool is a fine regulation of chromatin organization and gene expression. Acquiring a lineage-specific 3D genome architecture constitutes a crucial modulator of muscle stem cell function during development, in the adult stage, in physiological and pathological conditions. The context-dependent relationship between genome structure, such as accessibility and chromatin compartmentalization, and their functional effects will be analysed considering the improved 3D epigenome knowledge, underlining the intimate liaison between environmental encounters and epigenetics.
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Affiliation(s)
- Philina Santarelli
- INGM Istituto Nazionale Genetica Molecolare Romeo ed Enrica Invernizzi, Milan, Italy
| | - Valentina Rosti
- INGM Istituto Nazionale Genetica Molecolare Romeo ed Enrica Invernizzi, Milan, Italy; CNR Institute of Biomedical Technologies, Milan, Italy
| | - Maria Vivo
- Università degli studi di Salerno, Fisciano, Italy.
| | - Chiara Lanzuolo
- INGM Istituto Nazionale Genetica Molecolare Romeo ed Enrica Invernizzi, Milan, Italy; CNR Institute of Biomedical Technologies, Milan, Italy.
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3
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Mandal M, Maienschein-Cline M, Hu Y, Mohsin A, Veselits ML, Wright NE, Okoreeh MK, Yoon YM, Veselits J, Georgopoulos K, Clark MR. BRWD1 orchestrates small pre-B cell chromatin topology by converting static to dynamic cohesin. Nat Immunol 2024; 25:129-141. [PMID: 37985858 DOI: 10.1038/s41590-023-01666-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Accepted: 09/29/2023] [Indexed: 11/22/2023]
Abstract
Lymphocyte development consists of sequential and mutually exclusive cell states of proliferative selection and antigen receptor gene recombination. Transitions between each state require large, coordinated changes in epigenetic landscapes and transcriptional programs. How this occurs remains unclear. Here we demonstrate that in small pre-B cells, the lineage and stage-specific epigenetic reader bromodomain and WD repeat-containing protein 1 (BRWD1) reorders three-dimensional chromatin topology to affect the transition between proliferative and gene recombination molecular programs. BRWD1 regulated the switch between poised and active enhancers interacting with promoters, and coordinated this switch with Igk locus contraction. BRWD1 did so by converting chromatin-bound static to dynamic cohesin competent to mediate long-range looping. ATP-depletion revealed cohesin conversion to be the main energetic mechanism dictating dynamic chromatin looping. Our findings provide a new mechanism of cohesin regulation and reveal how cohesin function can be dictated by lineage contextual mechanisms to facilitate specific cell fate transitions.
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Affiliation(s)
- Malay Mandal
- Department of Medicine, Section of Rheumatology and Gwen Knapp Center for Lupus and Immunology Research, University of Chicago, Chicago, IL, USA.
| | | | - Yeguang Hu
- Cutaneous Biology Research Center, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Azam Mohsin
- Program in Immunology, Stanford University School of Medicine, Stanford, CA, USA
| | - Margaret L Veselits
- Department of Medicine, Section of Rheumatology and Gwen Knapp Center for Lupus and Immunology Research, University of Chicago, Chicago, IL, USA
| | - Nathaniel E Wright
- Department of Medicine, Section of Rheumatology and Gwen Knapp Center for Lupus and Immunology Research, University of Chicago, Chicago, IL, USA
| | - Michael K Okoreeh
- Department of Medicine, Section of Rheumatology and Gwen Knapp Center for Lupus and Immunology Research, University of Chicago, Chicago, IL, USA
| | - Young Me Yoon
- Department of Medicine, Section of Rheumatology and Gwen Knapp Center for Lupus and Immunology Research, University of Chicago, Chicago, IL, USA
| | - Jacob Veselits
- Department of Medicine, Section of Rheumatology and Gwen Knapp Center for Lupus and Immunology Research, University of Chicago, Chicago, IL, USA
| | - Katia Georgopoulos
- Cutaneous Biology Research Center, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Marcus R Clark
- Department of Medicine, Section of Rheumatology and Gwen Knapp Center for Lupus and Immunology Research, University of Chicago, Chicago, IL, USA.
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4
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Brennan KJ, Weilert M, Krueger S, Pampari A, Liu HY, Yang AWH, Morrison JA, Hughes TR, Rushlow CA, Kundaje A, Zeitlinger J. Chromatin accessibility in the Drosophila embryo is determined by transcription factor pioneering and enhancer activation. Dev Cell 2023; 58:1898-1916.e9. [PMID: 37557175 PMCID: PMC10592203 DOI: 10.1016/j.devcel.2023.07.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 05/09/2023] [Accepted: 07/13/2023] [Indexed: 08/11/2023]
Abstract
Chromatin accessibility is integral to the process by which transcription factors (TFs) read out cis-regulatory DNA sequences, but it is difficult to differentiate between TFs that drive accessibility and those that do not. Deep learning models that learn complex sequence rules provide an unprecedented opportunity to dissect this problem. Using zygotic genome activation in Drosophila as a model, we analyzed high-resolution TF binding and chromatin accessibility data with interpretable deep learning and performed genetic validation experiments. We identify a hierarchical relationship between the pioneer TF Zelda and the TFs involved in axis patterning. Zelda consistently pioneers chromatin accessibility proportional to motif affinity, whereas patterning TFs augment chromatin accessibility in sequence contexts where they mediate enhancer activation. We conclude that chromatin accessibility occurs in two tiers: one through pioneering, which makes enhancers accessible but not necessarily active, and the second when the correct combination of TFs leads to enhancer activation.
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Affiliation(s)
- Kaelan J Brennan
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Melanie Weilert
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Sabrina Krueger
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Anusri Pampari
- Department of Computer Science, Stanford University, Palo Alto, CA 94305, USA
| | - Hsiao-Yun Liu
- Department of Biology, New York University, New York, NY 10003, USA
| | - Ally W H Yang
- Donnelly Centre, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Jason A Morrison
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Timothy R Hughes
- Donnelly Centre, University of Toronto, Toronto, ON M5S 3E1, Canada
| | | | - Anshul Kundaje
- Department of Computer Science, Stanford University, Palo Alto, CA 94305, USA; Department of Genetics, Stanford University, Palo Alto, CA 94305, USA
| | - Julia Zeitlinger
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA; Department of Pathology & Laboratory Medicine, The University of Kansas Medical Center, Kansas City, KS 66160, USA.
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5
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Enkhmandakh B, Joshi P, Robson P, Vijaykumar A, Mina M, Shin DG, Bayarsaihan D. Single-cell Transcriptome Landscape of DNA Methylome Regulators Associated with Orofacial Clefts in the Mouse Dental Pulp. Cleft Palate Craniofac J 2023:10556656231172296. [PMID: 37161276 DOI: 10.1177/10556656231172296] [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: 05/11/2023] Open
Abstract
OBJECTIVE Significant evidence links epigenetic processes governing the dynamics of DNA methylation and demethylation to an increased risk of syndromic and nonsyndromic cleft lip and/or cleft palate (CL/P). Previously, we characterized mesenchymal stem/stromal cells (MSCs) at different stages of osteogenic differentiation in the mouse incisor dental pulp. The main objective of this research was to characterize the transcriptional landscape of regulatory genes associated with DNA methylation and demethylation at a single-cell resolution. DESIGN We used single-cell RNA sequencing (scRNA-seq) data to characterize transcriptome in individual subpopulations of MSCs in the mouse incisor dental pulp. SETTINGS The biomedical research institution. PATIENTS/PARTICIPANTS This study did not include patients. INTERVENTIONS This study collected and analyzed data on the single-cell RNA expssion in the mouse incisor dental pulp. MAIN OUTCOME MEASURE(S) Molecular regulators of DNA methylation/demethylation exhibit differential transcriptional landscape in different subpopulations of osteogenic progenitor cells. RESULTS scRNA-seq analysis revealed that genes encoding DNA methylation and demethylation enzymes (DNA methyltransferases and members of the ten-eleven translocation family of methylcytosine dioxygenases), methyl-DNA binding domain proteins, as well as transcription factors and chromatin remodeling proteins that cooperate with DNA methylation machinery are differentially expressed within distinct subpopulations of MSCs that undergo different stages of osteogenic differentiation. CONCLUSIONS These findings suggest some mechanistic insights into a potential link between epigenetic alterations and multifactorial causes of CL/P phenotypes.
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Affiliation(s)
- Badam Enkhmandakh
- Center for Regenerative Medicine and Skeletal Development, Department of Reconstructive Sciences, University of Connecticut Health Center, Farmington, CT, USA
| | - Pujan Joshi
- Computer Science and Engineering Department, University of Connecticut, Storrs, CT, USA
| | - Paul Robson
- The Jackson Laboratory for Genomic Medicine, Single Cell Biology Laboratory, Farmington, CT, USA
| | - Anushree Vijaykumar
- Department of Craniofacial Sciences, University of Connecticut Health Center, Farmington, CT, USA
| | - Mina Mina
- Department of Craniofacial Sciences, University of Connecticut Health Center, Farmington, CT, USA
| | - Dong-Guk Shin
- Computer Science and Engineering Department, University of Connecticut, Storrs, CT, USA
| | - Dashzeveg Bayarsaihan
- Center for Regenerative Medicine and Skeletal Development, Department of Reconstructive Sciences, University of Connecticut Health Center, Farmington, CT, USA
- Institute for System Genomics, University of Connecticut, Storrs, CT, USA
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6
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Ling L, Mühling B, Jaenichen R, Gompel N. Increased chromatin accessibility promotes the evolution of a transcriptional silencer in Drosophila. SCIENCE ADVANCES 2023; 9:eade6529. [PMID: 36800429 PMCID: PMC9937571 DOI: 10.1126/sciadv.ade6529] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 01/17/2023] [Indexed: 06/18/2023]
Abstract
The loss of discrete morphological traits, the most common evolutionary transition, is typically driven by changes in developmental gene expression. Mutations accumulating in regulatory elements of these genes can disrupt DNA binding sites for transcription factors patterning their spatial expression, or delete entire enhancers. Regulatory elements, however, may be silenced through changes in chromatin accessibility or the emergence of repressive elements. Here, we show that increased chromatin accessibility at the gene yellow, combined with the gain of a repressor site, underlies the loss of a wing spot pigmentation pattern in a Drosophila species. The gain of accessibility of this repressive element is regulated by E93, a transcription factor governing the progress of metamorphosis. This convoluted evolutionary scenario contrasts with the parsimonious mutational paths generally envisioned and often documented for morphological losses. It illustrates how evolutionary changes in chromatin accessibility may directly contribute to morphological diversification.
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Alatawneh R, Salomon Y, Eshel R, Orenstein Y, Birnbaum RY. Deciphering transcription factors and their corresponding regulatory elements during inhibitory interneuron differentiation using deep neural networks. Front Cell Dev Biol 2023; 11:1034604. [PMID: 36891511 PMCID: PMC9986276 DOI: 10.3389/fcell.2023.1034604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 01/23/2023] [Indexed: 02/22/2023] Open
Abstract
During neurogenesis, the generation and differentiation of neuronal progenitors into inhibitory gamma-aminobutyric acid-containing interneurons is dependent on the combinatorial activity of transcription factors (TFs) and their corresponding regulatory elements (REs). However, the roles of neuronal TFs and their target REs in inhibitory interneuron progenitors are not fully elucidated. Here, we developed a deep-learning-based framework to identify enriched TF motifs in gene REs (eMotif-RE), such as poised/repressed enhancers and putative silencers. Using epigenetic datasets (e.g., ATAC-seq and H3K27ac/me3 ChIP-seq) from cultured interneuron-like progenitors, we distinguished between active enhancer sequences (open chromatin with H3K27ac) and non-active enhancer sequences (open chromatin without H3K27ac). Using our eMotif-RE framework, we discovered enriched motifs of TFs such as ASCL1, SOX4, and SOX11 in the active enhancer set suggesting a cooperativity function for ASCL1 and SOX4/11 in active enhancers of neuronal progenitors. In addition, we found enriched ZEB1 and CTCF motifs in the non-active set. Using an in vivo enhancer assay, we showed that most of the tested putative REs from the non-active enhancer set have no enhancer activity. Two of the eight REs (25%) showed function as poised enhancers in the neuronal system. Moreover, mutated REs for ZEB1 and CTCF motifs increased their in vivo activity as enhancers indicating a repressive effect of ZEB1 and CTCF on these REs that likely function as repressed enhancers or silencers. Overall, our work integrates a novel framework based on deep learning together with a functional assay that elucidated novel functions of TFs and their corresponding REs. Our approach can be applied to better understand gene regulation not only in inhibitory interneuron differentiation but in other tissue and cell types.
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Affiliation(s)
- Rawan Alatawneh
- Department of Life Sciences, Faculty of Natural Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.,The Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Yahel Salomon
- School of Electrical and Computer Engineering, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Reut Eshel
- Department of Life Sciences, Faculty of Natural Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.,The Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Yaron Orenstein
- School of Electrical and Computer Engineering, Ben-Gurion University of the Negev, Beer-Sheva, Israel.,Department of Computer Science, Bar-Ilan University, Ramat Gan, Israel.,The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
| | - Ramon Y Birnbaum
- Department of Life Sciences, Faculty of Natural Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.,The Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
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8
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Giacoman-Lozano M, Meléndez-Ramírez C, Martinez-Ledesma E, Cuevas-Diaz Duran R, Velasco I. Epigenetics of neural differentiation: Spotlight on enhancers. Front Cell Dev Biol 2022; 10:1001701. [PMID: 36313573 PMCID: PMC9606577 DOI: 10.3389/fcell.2022.1001701] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2022] [Accepted: 10/03/2022] [Indexed: 11/28/2022] Open
Abstract
Neural induction, both in vivo and in vitro, includes cellular and molecular changes that result in phenotypic specialization related to specific transcriptional patterns. These changes are achieved through the implementation of complex gene regulatory networks. Furthermore, these regulatory networks are influenced by epigenetic mechanisms that drive cell heterogeneity and cell-type specificity, in a controlled and complex manner. Epigenetic marks, such as DNA methylation and histone residue modifications, are highly dynamic and stage-specific during neurogenesis. Genome-wide assessment of these modifications has allowed the identification of distinct non-coding regulatory regions involved in neural cell differentiation, maturation, and plasticity. Enhancers are short DNA regulatory regions that bind transcription factors (TFs) and interact with gene promoters to increase transcriptional activity. They are of special interest in neuroscience because they are enriched in neurons and underlie the cell-type-specificity and dynamic gene expression profiles. Classification of the full epigenomic landscape of neural subtypes is important to better understand gene regulation in brain health and during diseases. Advances in novel next-generation high-throughput sequencing technologies, genome editing, Genome-wide association studies (GWAS), stem cell differentiation, and brain organoids are allowing researchers to study brain development and neurodegenerative diseases with an unprecedented resolution. Herein, we describe important epigenetic mechanisms related to neurogenesis in mammals. We focus on the potential roles of neural enhancers in neurogenesis, cell-fate commitment, and neuronal plasticity. We review recent findings on epigenetic regulatory mechanisms involved in neurogenesis and discuss how sequence variations within enhancers may be associated with genetic risk for neurological and psychiatric disorders.
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Affiliation(s)
- Mayela Giacoman-Lozano
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Monterrey, NL, Mexico
| | - César Meléndez-Ramírez
- Instituto de Fisiología Celular—Neurociencias, Universidad Nacional Autónoma de Mexico, Mexico City, Mexico
- Laboratorio de Reprogramación Celular, Instituto Nacional de Neurología y Neurocirugía “Manuel Velasco Suárez”, Mexico City, Mexico
| | - Emmanuel Martinez-Ledesma
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Monterrey, NL, Mexico
- Tecnologico de Monterrey, The Institute for Obesity Research, Monterrey, NL, Mexico
| | - Raquel Cuevas-Diaz Duran
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Monterrey, NL, Mexico
- *Correspondence: Raquel Cuevas-Diaz Duran, ; Iván Velasco,
| | - Iván Velasco
- Instituto de Fisiología Celular—Neurociencias, Universidad Nacional Autónoma de Mexico, Mexico City, Mexico
- Laboratorio de Reprogramación Celular, Instituto Nacional de Neurología y Neurocirugía “Manuel Velasco Suárez”, Mexico City, Mexico
- *Correspondence: Raquel Cuevas-Diaz Duran, ; Iván Velasco,
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9
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Boyling A, Perez-Siles G, Kennerson ML. Structural Variation at a Disease Mutation Hotspot: Strategies to Investigate Gene Regulation and the 3D Genome. Front Genet 2022; 13:842860. [PMID: 35401663 PMCID: PMC8990796 DOI: 10.3389/fgene.2022.842860] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Accepted: 02/21/2022] [Indexed: 12/18/2022] Open
Abstract
A rare form of X-linked Charcot-Marie-Tooth neuropathy, CMTX3, is caused by an interchromosomal insertion occurring at chromosome Xq27.1. Interestingly, eight other disease phenotypes have been associated with insertions (or insertion-deletions) occurring at the same genetic locus. To date, the pathogenic mechanism underlying most of these diseases remains unsolved, although local gene dysregulation has clearly been implicated in at least two phenotypes. The challenges of accessing disease-relevant tissue and modelling these complex genomic rearrangements has led to this research impasse. We argue that recent technological advancements can overcome many of these challenges, particularly induced pluripotent stem cells (iPSC) and their capacity to provide access to patient-derived disease-relevant tissue. However, to date these valuable tools have not been utilized to investigate the disease-associated insertions at chromosome Xq27.1. Therefore, using CMTX3 as a reference disease, we propose an experimental approach that can be used to explore these complex mutations, as well as similar structural variants located elsewhere in the genome. The mutational hotspot at Xq27.1 is a valuable disease paradigm with the potential to improve our understanding of the pathogenic consequences of complex structural variation, and more broadly, refine our knowledge of the multifaceted process of long-range gene regulation. Intergenic structural variation is a critically understudied class of mutation, although it is likely to contribute significantly to unsolved genetic disease.
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Affiliation(s)
- Alexandra Boyling
- Northcott Neuroscience Laboratory, ANZAC Research Institute, Sydney, NSW, Australia
- Sydney Medical School, University of Sydney, Sydney, NSW, Australia
- *Correspondence: Alexandra Boyling, ; Marina L. Kennerson,
| | - Gonzalo Perez-Siles
- Northcott Neuroscience Laboratory, ANZAC Research Institute, Sydney, NSW, Australia
- Sydney Medical School, University of Sydney, Sydney, NSW, Australia
| | - Marina L. Kennerson
- Northcott Neuroscience Laboratory, ANZAC Research Institute, Sydney, NSW, Australia
- Sydney Medical School, University of Sydney, Sydney, NSW, Australia
- Molecular Medicine Laboratory, Concord Repatriation General Hospital, Sydney, NSW, Australia
- *Correspondence: Alexandra Boyling, ; Marina L. Kennerson,
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10
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Stutt N, Song M, Wilson MD, Scott IC. Cardiac specification during gastrulation - The Yellow Brick Road leading to Tinman. Semin Cell Dev Biol 2021; 127:46-58. [PMID: 34865988 DOI: 10.1016/j.semcdb.2021.11.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 11/05/2021] [Accepted: 11/11/2021] [Indexed: 02/07/2023]
Abstract
The question of how the heart develops, and the genetic networks governing this process have become intense areas of research over the past several decades. This research is propelled by classical developmental studies and potential clinical applications to understand and treat congenital conditions in which cardiac development is disrupted. Discovery of the tinman gene in Drosophila, and examination of its vertebrate homolog Nkx2.5, along with other core cardiac transcription factors has revealed how cardiac progenitor differentiation and maturation drives heart development. Careful observation of cardiac morphogenesis along with lineage tracing approaches indicated that cardiac progenitors can be divided into two broad classes of cells, namely the first and second heart fields, that contribute to the heart in two distinct waves of differentiation. Ample evidence suggests that the fate of individual cardiac progenitors is restricted to distinct cardiac structures quite early in development, well before the expression of canonical cardiac progenitor markers like Nkx2.5. Here we review the initial specification of cardiac progenitors, discuss evidence for the early patterning of cardiac progenitors during gastrulation, and consider how early gene expression programs and epigenetic patterns can direct their development. A complete understanding of when and how the developmental potential of cardiac progenitors is determined, and their potential plasticity, is of great interest developmentally and also has important implications for both the study of congenital heart disease and therapeutic approaches based on cardiac stem cell programming.
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Affiliation(s)
- Nathan Stutt
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON M5G0A4, Canada; Department of Molecular Genetics, University of Toronto, Toronto, ON, M5S1A8, Canada
| | - Mengyi Song
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, Toronto, ON M5G0A4, Canada; Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON M5G0A4, Canada; Department of Molecular Genetics, University of Toronto, Toronto, ON, M5S1A8, Canada
| | - Michael D Wilson
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, Toronto, ON M5G0A4, Canada; Department of Molecular Genetics, University of Toronto, Toronto, ON, M5S1A8, Canada
| | - Ian C Scott
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON M5G0A4, Canada; Department of Molecular Genetics, University of Toronto, Toronto, ON, M5S1A8, Canada.
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11
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Arenas-Mena C, Miljovska S, Rice EJ, Gurges J, Shashikant T, Wang Z, Ercan S, Danko CG. Identification and prediction of developmental enhancers in sea urchin embryos. BMC Genomics 2021; 22:751. [PMID: 34666684 PMCID: PMC8527612 DOI: 10.1186/s12864-021-07936-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Accepted: 06/28/2021] [Indexed: 11/21/2022] Open
Abstract
Background The transcription of developmental regulatory genes is often controlled by multiple cis-regulatory elements. The identification and functional characterization of distal regulatory elements remains challenging, even in tractable model organisms like sea urchins. Results We evaluate the use of chromatin accessibility, transcription and RNA Polymerase II for their ability to predict enhancer activity of genomic regions in sea urchin embryos. ATAC-seq, PRO-seq, and Pol II ChIP-seq from early and late blastula embryos are manually contrasted with experimental cis-regulatory analyses available in sea urchin embryos, with particular attention to common developmental regulatory elements known to have enhancer and silencer functions differentially deployed among embryonic territories. Using the three functional genomic data types, machine learning models are trained and tested to classify and quantitatively predict the enhancer activity of several hundred genomic regions previously validated with reporter constructs in vivo. Conclusions Overall, chromatin accessibility and transcription have substantial power for predicting enhancer activity. For promoter-overlapping cis-regulatory elements in particular, the distribution of Pol II is the best predictor of enhancer activity in blastula embryos. Furthermore, ATAC- and PRO-seq predictive value is stage dependent for the promoter-overlapping subset. This suggests that the sequence of regulatory mechanisms leading to transcriptional activation have distinct relevance at different levels of the developmental gene regulatory hierarchy deployed during embryogenesis. Supplementary Information The online version contains supplementary material available at 10.1186/s12864-021-07936-0.
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Affiliation(s)
- César Arenas-Mena
- College of Staten Island, The City University of New York (CUNY), Staten Island, NY, 10314, USA. .,Programs in Biology and Biochemistry, The Graduate Center, CUNY, New York, NY, 10016, USA.
| | - Sofija Miljovska
- Department of Biology, New York University, New York, NY, 10003, USA
| | - Edward J Rice
- Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, NY, 14853, USA
| | - Justin Gurges
- College of Staten Island, The City University of New York (CUNY), Staten Island, NY, 10314, USA
| | - Tanvi Shashikant
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Zihe Wang
- College of Staten Island, The City University of New York (CUNY), Staten Island, NY, 10314, USA
| | - Sevinç Ercan
- Department of Biology, New York University, New York, NY, 10003, USA.,Center for Genomics and Systems Biology, New York University, New York, NY, 10003, USA
| | - Charles G Danko
- Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, NY, 14853, USA.,Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, 14853, USA
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12
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Waymack R, Gad M, Wunderlich Z. Molecular competition can shape enhancer activity in the Drosophila embryo. iScience 2021; 24:103034. [PMID: 34568782 PMCID: PMC8449247 DOI: 10.1016/j.isci.2021.103034] [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: 06/07/2021] [Revised: 07/27/2021] [Accepted: 08/20/2021] [Indexed: 01/12/2023] Open
Abstract
Transgenic reporters allow the measurement of regulatory DNA activity in vivo and consequently have long been useful tools for studying enhancers. Despite their utility, few studies have investigated the effects these reporters may have on the expression of other genes. Understanding these effects is required to accurately interpret reporter data and characterize gene regulatory mechanisms. By measuring the expression of Kruppel (Kr) enhancer reporters in live Drosophila embryos, we find reporters inhibit one another’s expression and that of a nearby endogenous gene. Using synthetic transcription factor (TF) binding site arrays, we present evidence that competition for TFs is partially responsible for the observed transcriptional inhibition. We develop a simple thermodynamic model that predicts competition of the measured magnitude specifically when TF binding is restricted to distinct nuclear subregions. Our findings underline an unexpected role of the non-homogenous nature of the nucleus in regulating gene expression. Live tracking of transcription reveals competition between transgenic reporters Transgenic reporters can also depress the expression of a neighboring gene Expression inhibition is in part because of competition for transcription factors (TFs) Competition is predicted with a model that restricts TFs to sub-nuclear “hubs”
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Affiliation(s)
- Rachel Waymack
- Department of Developmental and Cell Biology, University of California, Irvine, CA 92697, USA
| | - Mario Gad
- Department of Developmental and Cell Biology, University of California, Irvine, CA 92697, USA
| | - Zeba Wunderlich
- Department of Developmental and Cell Biology, University of California, Irvine, CA 92697, USA.,Department of Biology, Boston University, 610 Commonwealth Ave., Boston, MA 02215, USA.,Biological Design Center, Boston University, 610 Commonwealth Avenue, Boston, MA 02215, USA
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Abstract
Form diversity is fueled by changes in the expression of genes that build organisms. New expression often results from the emergence of new DNA switches, known as transcriptional enhancers. Many enhancers are thought to appear through the recycling of older enhancers, a process called evolutionary co-option. Enhancer co-option is difficult to assess, and the molecular mechanisms explaining its prevalence are elusive. Using state-of-the-art quantification and analyses, we reveal that the sequences of an ancestral and a derived enhancer overlap extensively. They contain specific binding sites for regulators imparting spatial activities. We found that the two enhancers also share a site facilitating access to chromatin in a region where they overlap. The diversity of forms in multicellular organisms originates largely from the spatial redeployment of developmental genes [S. B. Carroll, Cell 134, 25–36 (2008)]. Several scenarios can explain the emergence of cis-regulatory elements that govern novel aspects of a gene expression pattern [M. Rebeiz, M. Tsiantis, Curr. Opin. Genet. Dev. 45, 115–123 (2017)]. One scenario, enhancer co-option, holds that a DNA sequence producing an ancestral regulatory activity also becomes the template for a new regulatory activity, sharing regulatory information. While enhancer co-option might fuel morphological diversification, it has rarely been documented [W. J. Glassford et al., Dev. Cell 34, 520–531 (2015)]. Moreover, if two regulatory activities are borne from the same sequence, their modularity, considered a defining feature of enhancers [J. Banerji, L. Olson, W. Schaffner, Cell 33, 729–740 (1983)], might be affected by pleiotropy. Sequence overlap may thereby play a determinant role in enhancer function and evolution. Here, we investigated this problem with two regulatory activities of the Drosophila gene yellow, the novel spot enhancer and the ancestral wing blade enhancer. We used precise and comprehensive quantification of each activity in Drosophila wings to systematically map their sequences along the locus. We show that the spot enhancer has co-opted the sequences of the wing blade enhancer. We also identified a pleiotropic site necessary for DNA accessibility of a shared regulatory region. While the evolutionary steps leading to the derived activity are still unknown, such pleiotropy suggests that enhancer accessibility could be one of the molecular mechanisms seeding evolutionary co-option.
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