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DeCotiis-Mauro J, Han SM, Mello H, Goyeneche C, Marchesini-Tovar G, Jin L, Bellofatto V, Lukac DM. The cellular Notch1 protein promotes KSHV reactivation in an Rta-dependent manner. J Virol 2024:e0078824. [PMID: 38975769 DOI: 10.1128/jvi.00788-24] [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: 05/06/2024] [Accepted: 06/05/2024] [Indexed: 07/09/2024] Open
Abstract
The cellular Notch signal transduction pathway is intimately associated with infections by Kaposi's sarcoma-associated herpesvirus (KSHV) and other gamma-herpesviruses. RBP-Jk, the cellular DNA binding component of the canonical Notch pathway, is the key Notch downstream effector protein in virus-infected and uninfected animal cells. Reactivation of KSHV from latency requires the viral lytic switch protein, Rta, to form complexes with RBP-Jk on numerous sites within the viral DNA. Constitutive Notch activity is essential for KSHV pathophysiology in models of Kaposi's sarcoma (KS) and Primary Effusion Lymphoma (PEL), and we demonstrate that Notch1 is also constitutively active in infected Vero cells. Although the KSHV genome contains >100 RBP-Jk DNA motifs, we show that none of the four isoforms of activated Notch can productively reactivate the virus from latency in a highly quantitative trans-complementing reporter virus system. Nevertheless, Notch contributed positively to reactivation because broad inhibition of Notch1-4 with gamma-secretase inhibitor (GSI) or expression of dominant negative mastermind-like1 (dnMAML1) coactivators severely reduced production of infectious KSHV from Vero cells. Reduction of KSHV production is associated with gene-specific reduction of viral transcription in both Vero and PEL cells. Specific inhibition of Notch1 by siRNA partially reduces the production of infectious KSHV, and NICD1 forms promoter-specific complexes with viral DNA during reactivation. We conclude that constitutive Notch activity is required for the robust production of infectious KSHV, and our results implicate activated Notch1 as a pro-viral member of a MAML1/RBP-Jk/DNA complex during viral reactivation. IMPORTANCE Kaposi's sarcoma-associated herpesvirus (KSHV) manipulates the host cell oncogenic Notch signaling pathway for viral reactivation from latency and cell pathogenesis. KSHV reactivation requires that the viral protein Rta functionally interacts with RBP-Jk, the DNA-binding component of the Notch pathway, and with promoter DNA to drive transcription of productive cycle genes. We show that the Notch pathway is constitutively active during KSHV reactivation and is essential for robust production of infectious virus progeny. Inhibiting Notch during reactivation reduces the expression of specific viral genes yet does not affect the growth of the host cells. Although Notch cannot reactivate KSHV alone, the requisite expression of Rta reveals a previously unappreciated role for Notch in reactivation. We propose that activated Notch cooperates with Rta in a promoter-specific manner that is partially programmed by Rta's ability to redistribute RBP-Jk DNA binding to the virus during reactivation.
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Affiliation(s)
- Jennifer DeCotiis-Mauro
- Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Rutgers University, Newark, New Jersey, USA
- School of Graduate Studies, Rutgers Biomedical and Health Sciences, Health Science Campus at Newark, Rutgers University, Newark, New Jersey, USA
| | - Sun M Han
- Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Rutgers University, Newark, New Jersey, USA
- School of Graduate Studies, Rutgers Biomedical and Health Sciences, Health Science Campus at Newark, Rutgers University, Newark, New Jersey, USA
| | - Helena Mello
- Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Rutgers University, Newark, New Jersey, USA
- School of Graduate Studies, Rutgers Biomedical and Health Sciences, Health Science Campus at Newark, Rutgers University, Newark, New Jersey, USA
| | - Corey Goyeneche
- Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Rutgers University, Newark, New Jersey, USA
- School of Graduate Studies, Rutgers Biomedical and Health Sciences, Health Science Campus at Newark, Rutgers University, Newark, New Jersey, USA
| | - Giuseppina Marchesini-Tovar
- Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Rutgers University, Newark, New Jersey, USA
- School of Graduate Studies, Rutgers Biomedical and Health Sciences, Health Science Campus at Newark, Rutgers University, Newark, New Jersey, USA
| | - Lianhua Jin
- Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Rutgers University, Newark, New Jersey, USA
- School of Graduate Studies, Rutgers Biomedical and Health Sciences, Health Science Campus at Newark, Rutgers University, Newark, New Jersey, USA
| | - Vivian Bellofatto
- Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Rutgers University, Newark, New Jersey, USA
- School of Graduate Studies, Rutgers Biomedical and Health Sciences, Health Science Campus at Newark, Rutgers University, Newark, New Jersey, USA
| | - David M Lukac
- Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Rutgers University, Newark, New Jersey, USA
- School of Graduate Studies, Rutgers Biomedical and Health Sciences, Health Science Campus at Newark, Rutgers University, Newark, New Jersey, USA
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2
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Bower G, Hollingsworth EW, Jacinto S, Clock B, Cao K, Liu M, Dziulko A, Alcaina-Caro A, Xu Q, Skowronska-Krawczyk D, Lopez-Rios J, Dickel DE, Bardet AF, Pennacchio LA, Visel A, Kvon EZ. Conserved Cis-Acting Range Extender Element Mediates Extreme Long-Range Enhancer Activity in Mammals. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.26.595809. [PMID: 38826394 PMCID: PMC11142232 DOI: 10.1101/2024.05.26.595809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
While most mammalian enhancers regulate their cognate promoters over moderate distances of tens of kilobases (kb), some enhancers act over distances in the megabase range. The sequence features enabling such extreme-distance enhancer-promoter interactions remain elusive. Here, we used in vivo enhancer replacement experiments in mice to show that short- and medium-range enhancers cannot initiate gene expression at extreme-distance range. We uncover a novel conserved cis-acting element, Range EXtender (REX), that confers extreme-distance regulatory activity and is located next to a long-range enhancer of Sall1. The REX element itself has no endogenous enhancer activity. However, addition of the REX to other short- and mid-range enhancers substantially increases their genomic interaction range. In the most extreme example observed, addition of the REX increased the range of an enhancer by an order of magnitude, from its native 71kb to 840kb. The REX element contains highly conserved [C/T]AATTA homeodomain motifs. These motifs are enriched around long-range limb enhancers genome-wide, including the ZRS, a benchmark long-range limb enhancer of Shh. Mutating the [C/T]AATTA motifs within the ZRS does not affect its limb-specific enhancer activity at short range, but selectively abolishes its long-range activity, resulting in severe limb reduction in knock-in mice. In summary, we identify a sequence signature globally associated with long-range enhancer-promoter interactions and describe a prototypical REX element that is necessary and sufficient to confer extreme-distance gene activation by remote enhancers.
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Affiliation(s)
- Grace Bower
- Department of Developmental and Cell Biology, University of California, Irvine, CA 92967, USA
| | - Ethan W. Hollingsworth
- Department of Developmental and Cell Biology, University of California, Irvine, CA 92967, USA
- Medical Scientist Training Program, University of California, Irvine, CA 92967, USA
| | - Sandra Jacinto
- Department of Developmental and Cell Biology, University of California, Irvine, CA 92967, USA
| | - Benjamin Clock
- Department of Developmental and Cell Biology, University of California, Irvine, CA 92967, USA
| | - Kaitlyn Cao
- Department of Developmental and Cell Biology, University of California, Irvine, CA 92967, USA
| | - Mandy Liu
- Department of Developmental and Cell Biology, University of California, Irvine, CA 92967, USA
| | - Adam Dziulko
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Ana Alcaina-Caro
- Centro Andaluz de Biología del Desarrollo (CABD), CSIC-Universidad Pablo de Olavide-Junta de Andalucía, Seville, 41013, Spain
| | - Qianlan Xu
- Department of Physiology and Biophysics, Department of Ophthalmology, Center for Translational Vision Research, School of Medicine, University of California, Irvine, CA, USA
| | - Dorota Skowronska-Krawczyk
- Department of Physiology and Biophysics, Department of Ophthalmology, Center for Translational Vision Research, School of Medicine, University of California, Irvine, CA, USA
| | - Javier Lopez-Rios
- Centro Andaluz de Biología del Desarrollo (CABD), CSIC-Universidad Pablo de Olavide-Junta de Andalucía, Seville, 41013, Spain
| | - Diane E. Dickel
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Anaïs F. Bardet
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Université de Strasbourg, CNRS UMR7104, INSERM U1258, 67400 Illkirch, France
| | - Len A. Pennacchio
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- U.S. Department of Energy Joint Genome Institute, Walnut Creek, CA 94598, USA
- Comparative Biochemistry Program, University of California, Berkeley, CA 94720, USA
| | - Axel Visel
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- U.S. Department of Energy Joint Genome Institute, Walnut Creek, CA 94598, USA
- School of Natural Sciences, University of California, Merced, CA 95343, USA
| | - Evgeny Z. Kvon
- Department of Developmental and Cell Biology, University of California, Irvine, CA 92967, USA
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3
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Sabarís G, Ortíz DM, Laiker I, Mayansky I, Naik S, Cavalli G, Stern DL, Preger-Ben Noon E, Frankel N. The Density of Regulatory Information Is a Major Determinant of Evolutionary Constraint on Noncoding DNA in Drosophila. Mol Biol Evol 2024; 41:msae004. [PMID: 38364113 PMCID: PMC10871701 DOI: 10.1093/molbev/msae004] [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] [Received: 07/04/2023] [Revised: 11/26/2023] [Accepted: 01/05/2024] [Indexed: 02/18/2024] Open
Abstract
Evolutionary analyses have estimated that ∼60% of nucleotides in intergenic regions of the Drosophila melanogaster genome are functionally relevant, suggesting that regulatory information may be encoded more densely in intergenic regions than has been revealed by most functional dissections of regulatory DNA. Here, we approached this issue through a functional dissection of the regulatory region of the gene shavenbaby (svb). Most of the ∼90 kb of this large regulatory region is highly conserved in the genus Drosophila, though characterized enhancers occupy a small fraction of this region. By analyzing the regulation of svb in different contexts of Drosophila development, we found that the regulatory information that drives svb expression in the abdominal pupal epidermis is organized in a different way than the elements that drive svb expression in the embryonic epidermis. While in the embryonic epidermis svb is activated by compact enhancers separated by large inactive DNA regions, svb expression in the pupal epidermis is driven by regulatory information distributed over broader regions of svb cis-regulatory DNA. In the same vein, we observed that other developmental genes also display a dense distribution of putative regulatory elements in their regulatory regions. Furthermore, we found that a large percentage of conserved noncoding DNA of the Drosophila genome is contained within regions of open chromatin. These results suggest that part of the evolutionary constraint on noncoding DNA of Drosophila is explained by the density of regulatory information, which may be greater than previously appreciated.
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Affiliation(s)
- Gonzalo Sabarís
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad de Buenos Aires (UBA), Buenos Aires 1428, Argentina
- Institute of Human Genetics, UMR 9002 CNRS-Université de Montpellier, Montpellier, France
| | - Daniela M Ortíz
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad de Buenos Aires (UBA), Buenos Aires 1428, Argentina
| | - Ian Laiker
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad de Buenos Aires (UBA), Buenos Aires 1428, Argentina
| | - Ignacio Mayansky
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad de Buenos Aires (UBA), Buenos Aires 1428, Argentina
| | - Sujay Naik
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion—Israel Institute of Technology, Haifa 3109601, Israel
| | - Giacomo Cavalli
- Institute of Human Genetics, UMR 9002 CNRS-Université de Montpellier, Montpellier, France
| | - David L Stern
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Ella Preger-Ben Noon
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion—Israel Institute of Technology, Haifa 3109601, Israel
| | - Nicolás Frankel
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad de Buenos Aires (UBA), Buenos Aires 1428, Argentina
- Departamento de Ecología, Genética y Evolución, Facultad de Ciencias Exactas y Naturales (FCEN), Universidad de Buenos Aires (UBA), Buenos Aires 1428, Argentina
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4
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Martyn GE, Montgomery MT, Jones H, Guo K, Doughty BR, Linder J, Chen Z, Cochran K, Lawrence KA, Munson G, Pampari A, Fulco CP, Kelley DR, Lander ES, Kundaje A, Engreitz JM. Rewriting regulatory DNA to dissect and reprogram gene expression. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.20.572268. [PMID: 38187584 PMCID: PMC10769263 DOI: 10.1101/2023.12.20.572268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
Regulatory DNA sequences within enhancers and promoters bind transcription factors to encode cell type-specific patterns of gene expression. However, the regulatory effects and programmability of such DNA sequences remain difficult to map or predict because we have lacked scalable methods to precisely edit regulatory DNA and quantify the effects in an endogenous genomic context. Here we present an approach to measure the quantitative effects of hundreds of designed DNA sequence variants on gene expression, by combining pooled CRISPR prime editing with RNA fluorescence in situ hybridization and cell sorting (Variant-FlowFISH). We apply this method to mutagenize and rewrite regulatory DNA sequences in an enhancer and the promoter of PPIF in two immune cell lines. Of 672 variant-cell type pairs, we identify 497 that affect PPIF expression. These variants appear to act through a variety of mechanisms including disruption or optimization of existing transcription factor binding sites, as well as creation of de novo sites. Disrupting a single endogenous transcription factor binding site often led to large changes in expression (up to -40% in the enhancer, and -50% in the promoter). The same variant often had different effects across cell types and states, demonstrating a highly tunable regulatory landscape. We use these data to benchmark performance of sequence-based predictive models of gene regulation, and find that certain types of variants are not accurately predicted by existing models. Finally, we computationally design 185 small sequence variants (≤10 bp) and optimize them for specific effects on expression in silico. 84% of these rationally designed edits showed the intended direction of effect, and some had dramatic effects on expression (-100% to +202%). Variant-FlowFISH thus provides a powerful tool to map the effects of variants and transcription factor binding sites on gene expression, test and improve computational models of gene regulation, and reprogram regulatory DNA.
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Affiliation(s)
- Gabriella E Martyn
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
- Basic Science and Engineering Initiative, Stanford Children's Health, Betty Irene Moore Children's Heart Center, Stanford, CA, USA
| | - Michael T Montgomery
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
- Basic Science and Engineering Initiative, Stanford Children's Health, Betty Irene Moore Children's Heart Center, Stanford, CA, USA
| | - Hank Jones
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
- Basic Science and Engineering Initiative, Stanford Children's Health, Betty Irene Moore Children's Heart Center, Stanford, CA, USA
| | - Katherine Guo
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
- Basic Science and Engineering Initiative, Stanford Children's Health, Betty Irene Moore Children's Heart Center, Stanford, CA, USA
| | - Benjamin R Doughty
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
| | | | - Ziwei Chen
- Department of Computer Science, Stanford University, Stanford, CA, USA
| | - Kelly Cochran
- Department of Computer Science, Stanford University, Stanford, CA, USA
| | - Kathryn A Lawrence
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
| | - Glen Munson
- The Novo Nordisk Foundation Center for Genomic Mechanisms of Disease, Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Gene Regulation Observatory, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Anusri Pampari
- Department of Computer Science, Stanford University, Stanford, CA, USA
| | - Charles P Fulco
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Present Address: Sanofi, Cambridge, MA, USA
| | | | - Eric S Lander
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Department of Biology, MIT, Cambridge, MA, USA
- Department of Systems Biology, Harvard Medical School, Boston, MA, USA
| | - Anshul Kundaje
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
- Department of Computer Science, Stanford University, Stanford, CA, USA
| | - Jesse M Engreitz
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
- Basic Science and Engineering Initiative, Stanford Children's Health, Betty Irene Moore Children's Heart Center, Stanford, CA, USA
- The Novo Nordisk Foundation Center for Genomic Mechanisms of Disease, Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Gene Regulation Observatory, Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Stanford Cardiovascular Institute, Stanford University, Stanford, CA, USA
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5
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Song BP, Ragsac MF, Tellez K, Jindal GA, Grudzien JL, Le SH, Farley EK. Diverse logics and grammar encode notochord enhancers. Cell Rep 2023; 42:112052. [PMID: 36729834 PMCID: PMC10387507 DOI: 10.1016/j.celrep.2023.112052] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 11/07/2022] [Accepted: 01/17/2023] [Indexed: 02/03/2023] Open
Abstract
The notochord is a defining feature of all chordates. The transcription factors Zic and ETS regulate enhancer activity within the notochord. We conduct high-throughput screens of genomic elements within developing Ciona embryos to understand how Zic and ETS sites encode notochord activity. Our screen discovers an enhancer located near Lama, a gene critical for notochord development. Reversing the orientation of an ETS site within this enhancer abolishes expression, indicating that enhancer grammar is critical for notochord activity. Similarly organized clusters of Zic and ETS sites occur within mouse and human Lama1 introns. Within a Brachyury (Bra) enhancer, FoxA and Bra, in combination with Zic and ETS binding sites, are necessary and sufficient for notochord expression. This binding site logic also occurs within other Ciona and vertebrate Bra enhancers. Collectively, this study uncovers the importance of grammar within notochord enhancers and discovers signatures of enhancer logic and grammar conserved across chordates.
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Affiliation(s)
- Benjamin P Song
- Department of Medicine, Health Sciences, University of California San Diego, La Jolla, CA 92093, USA; Department of Molecular Biology, Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA; Biological Sciences Graduate Program, University of California San Diego, La Jolla, CA 92093, USA
| | - Michelle F Ragsac
- Department of Medicine, Health Sciences, University of California San Diego, La Jolla, CA 92093, USA; Department of Molecular Biology, Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA; Bioinformatics and Systems Biology Graduate Program, University of California San Diego, La Jolla, CA 92093, USA
| | - Krissie Tellez
- Department of Medicine, Health Sciences, University of California San Diego, La Jolla, CA 92093, USA; Department of Molecular Biology, Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA
| | - Granton A Jindal
- Department of Medicine, Health Sciences, University of California San Diego, La Jolla, CA 92093, USA; Department of Molecular Biology, Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA
| | - Jessica L Grudzien
- Department of Medicine, Health Sciences, University of California San Diego, La Jolla, CA 92093, USA; Department of Molecular Biology, Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA
| | - Sophia H Le
- Department of Medicine, Health Sciences, University of California San Diego, La Jolla, CA 92093, USA; Department of Molecular Biology, Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA
| | - Emma K Farley
- Department of Medicine, Health Sciences, University of California San Diego, La Jolla, CA 92093, USA; Department of Molecular Biology, Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA.
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6
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Bateman JR, Johnson JE. Altering enhancer-promoter linear distance impacts promoter competition in cis and in trans. Genetics 2022; 222:6617354. [PMID: 35748724 PMCID: PMC9434180 DOI: 10.1093/genetics/iyac098] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Accepted: 06/18/2022] [Indexed: 11/14/2022] Open
Abstract
In Drosophila, pairing of maternal and paternal homologs can permit trans-interactions between enhancers on one homolog and promoters on another, an example of a phenomenon called transvection. When chromosomes are paired, promoters in cis and in trans to an enhancer can compete for the enhancer's activity, but the parameters that govern this competition are as yet poorly understood. To assess how the linear spacing between an enhancer and promoter can influence promoter competition in Drosophila, we employed transgenic constructs wherein the eye-specific enhancer GMR is placed at varying distances from a heterologous hsp70 promoter driving a fluorescent reporter. While GMR activates the reporter to a high degree when the enhancer and promoter are spaced by a few hundred base pairs, activation is strongly attenuated when the enhancer is moved 3 kilobases away. By examining transcription of endogenous genes near the point of transgene insertion, we show that linear spacing of 3 kb between GMR and the hsp70 promoter results in elevated transcription of neighboring promoters, suggesting a loss of specificity between the enhancer and its intended transgenic target promoter. Furthermore, increasing spacing between GMR and hsp70 by just 100 bp can enhance transvection, resulting in increased activation of a promoter on a paired homolog at the expense of a promoter in cis to the enhancer. Finally, cis-/trans-promoter competition assays in which one promoter carries mutations to key core promoter elements show that GMR will skew its activity toward a wild type promoter, suggesting that an enhancer is in a balanced competition between its potential target promoters in cis and in trans.
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Affiliation(s)
- Jack R Bateman
- Biology Department, Bowdoin College, Brunswick, ME 04011, USA
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7
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DeepSTARR predicts enhancer activity from DNA sequence and enables the de novo design of synthetic enhancers. Nat Genet 2022; 54:613-624. [PMID: 35551305 DOI: 10.1038/s41588-022-01048-5] [Citation(s) in RCA: 69] [Impact Index Per Article: 34.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 03/08/2022] [Indexed: 02/06/2023]
Abstract
Enhancer sequences control gene expression and comprise binding sites (motifs) for different transcription factors (TFs). Despite extensive genetic and computational studies, the relationship between DNA sequence and regulatory activity is poorly understood, and de novo enhancer design has been challenging. Here, we built a deep-learning model, DeepSTARR, to quantitatively predict the activities of thousands of developmental and housekeeping enhancers directly from DNA sequence in Drosophila melanogaster S2 cells. The model learned relevant TF motifs and higher-order syntax rules, including functionally nonequivalent instances of the same TF motif that are determined by motif-flanking sequence and intermotif distances. We validated these rules experimentally and demonstrated that they can be generalized to humans by testing more than 40,000 wildtype and mutant Drosophila and human enhancers. Finally, we designed and functionally validated synthetic enhancers with desired activities de novo.
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8
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Weasner BP, Kumar JP. The early history of the eye-antennal disc of Drosophila melanogaster. Genetics 2022; 221:6573236. [PMID: 35460415 PMCID: PMC9071535 DOI: 10.1093/genetics/iyac041] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 03/04/2022] [Indexed: 12/15/2022] Open
Abstract
A pair of eye-antennal imaginal discs give rise to nearly all external structures of the adult Drosophila head including the compound eyes, ocelli, antennae, maxillary palps, head epidermis, and bristles. In the earliest days of Drosophila research, investigators would examine thousands of adult flies in search of viable mutants whose appearance deviated from the norm. The compound eyes are dispensable for viability and perturbations to their structure are easy to detect. As such, the adult compound eye and the developing eye-antennal disc emerged as focal points for studies of genetics and developmental biology. Since few tools were available at the time, early researchers put an enormous amount of thought into models that would explain their experimental observations-many of these hypotheses remain to be tested. However, these "ancient" studies have been lost to time and are no longer read or incorporated into today's literature despite the abundance of field-defining discoveries that are contained therein. In this FlyBook chapter, I will bring these forgotten classics together and draw connections between them and modern studies of tissue specification and patterning. In doing so, I hope to bring a larger appreciation of the contributions that the eye-antennal disc has made to our understanding of development as well as draw the readers' attention to the earliest studies of this important imaginal disc. Armed with the today's toolkit of sophisticated genetic and molecular methods and using the old papers as a guide, we can use the eye-antennal disc to unravel the mysteries of development.
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Affiliation(s)
- Brandon P Weasner
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Justin P Kumar
- Department of Biology, Indiana University, Bloomington, IN 47405, USA,Corresponding author: Department of Biology, Indiana University, Bloomington, IN 47405, USA.
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9
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Liu H, Gao J, Sun J, Li S, Zhang B, Wang Z, Zhou C, Sulis DB, Wang JP, Chiang VL, Li W. Dimerization of PtrMYB074 and PtrWRKY19 mediates transcriptional activation of PtrbHLH186 for secondary xylem development in Populus trichocarpa. THE NEW PHYTOLOGIST 2022; 234:918-933. [PMID: 35152419 PMCID: PMC9314101 DOI: 10.1111/nph.18028] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Accepted: 02/02/2022] [Indexed: 05/28/2023]
Abstract
Wood formation is controlled by transcriptional regulatory networks (TRNs) involving regulatory homeostasis determined by combinations of transcription factor (TF)-DNA and TF-TF interactions. Functions of TF-TF interactions in wood formation are still in the early stages of identification. PtrMYB074 is a woody dicot-specific TF in a TRN for wood formation in Populus trichocarpa. Here, using yeast two-hybrid and bimolecular fluorescence complementation, we conducted a genome-wide screening for PtrMYB074 interactors and identified 54 PtrMYB074-TF pairs. Of these pairs, 53 are novel. We focused on the PtrMYB074-PtrWRKY19 pair, the most highly expressed and xylem-specific interactor, and its direct transregulatory target, PtrbHLH186, the xylem-specific one of the pair's only two direct TF target genes. Using transient and CRISPR-mediated transgenesis in P. trichocarpa coupled with chromatin immunoprecipitation and electrophoretic mobility shift assays, we demonstrated that PtrMYB074 is recruited by PtrWRKY19 and that the PtrMYB074-PtrWRKY19 dimers are required to transactive PtrbHLH186. Overexpressing PtrbHLH186 in P. trichocarpa resulted in retarded plant growth, increased guaiacyl lignin, a higher proportion of smaller stem vessels and strong drought-tolerant phenotypes. Knowledge of the PtrMYB074-PtrWRKY19-PtrbHLH186 regulation may help design genetic controls of optimal growth and wood formation to maximize beneficial wood properties while minimizing negative effects on growth.
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Affiliation(s)
- Huizi Liu
- State Key Laboratory of Tree Genetics and BreedingNortheast Forestry UniversityHarbin150040China
| | - Jinghui Gao
- State Key Laboratory of Tree Genetics and BreedingNortheast Forestry UniversityHarbin150040China
| | - Jiatong Sun
- State Key Laboratory of Tree Genetics and BreedingNortheast Forestry UniversityHarbin150040China
| | - Shuang Li
- State Key Laboratory of Tree Genetics and BreedingNortheast Forestry UniversityHarbin150040China
| | - Baofeng Zhang
- State Key Laboratory of Tree Genetics and BreedingNortheast Forestry UniversityHarbin150040China
| | - Zhuwen Wang
- State Key Laboratory of Tree Genetics and BreedingNortheast Forestry UniversityHarbin150040China
| | - Chenguang Zhou
- State Key Laboratory of Tree Genetics and BreedingNortheast Forestry UniversityHarbin150040China
| | - Daniel Barletta Sulis
- Forest Biotechnology GroupDepartment of Forestry and Environmental ResourcesNorth Carolina State UniversityRaleighNC27695USA
| | - Jack P. Wang
- State Key Laboratory of Tree Genetics and BreedingNortheast Forestry UniversityHarbin150040China
- Forest Biotechnology GroupDepartment of Forestry and Environmental ResourcesNorth Carolina State UniversityRaleighNC27695USA
| | - Vincent L. Chiang
- State Key Laboratory of Tree Genetics and BreedingNortheast Forestry UniversityHarbin150040China
- Forest Biotechnology GroupDepartment of Forestry and Environmental ResourcesNorth Carolina State UniversityRaleighNC27695USA
| | - Wei Li
- State Key Laboratory of Tree Genetics and BreedingNortheast Forestry UniversityHarbin150040China
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10
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Dibaeinia P, Sinha S. Deciphering enhancer sequence using thermodynamics-based models and convolutional neural networks. Nucleic Acids Res 2021; 49:10309-10327. [PMID: 34508359 PMCID: PMC8501998 DOI: 10.1093/nar/gkab765] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 08/18/2021] [Accepted: 08/25/2021] [Indexed: 11/18/2022] Open
Abstract
Deciphering the sequence-function relationship encoded in enhancers holds the key to interpreting non-coding variants and understanding mechanisms of transcriptomic variation. Several quantitative models exist for predicting enhancer function and underlying mechanisms; however, there has been no systematic comparison of these models characterizing their relative strengths and shortcomings. Here, we interrogated a rich data set of neuroectodermal enhancers in Drosophila, representing cis- and trans- sources of expression variation, with a suite of biophysical and machine learning models. We performed rigorous comparisons of thermodynamics-based models implementing different mechanisms of activation, repression and cooperativity. Moreover, we developed a convolutional neural network (CNN) model, called CoNSEPT, that learns enhancer ‘grammar’ in an unbiased manner. CoNSEPT is the first general-purpose CNN tool for predicting enhancer function in varying conditions, such as different cell types and experimental conditions, and we show that such complex models can suggest interpretable mechanisms. We found model-based evidence for mechanisms previously established for the studied system, including cooperative activation and short-range repression. The data also favored one hypothesized activation mechanism over another and suggested an intriguing role for a direct, distance-independent repression mechanism. Our modeling shows that while fundamentally different models can yield similar fits to data, they vary in their utility for mechanistic inference. CoNSEPT is freely available at: https://github.com/PayamDiba/CoNSEPT.
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Affiliation(s)
- Payam Dibaeinia
- Department of Computer Science, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Saurabh Sinha
- Department of Computer Science, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.,Cancer Center at Illinois, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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11
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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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12
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Ramakrishnan AB, Chen L, Burby PE, Cadigan KM. Wnt target enhancer regulation by a CDX/TCF transcription factor collective and a novel DNA motif. Nucleic Acids Res 2021; 49:8625-8641. [PMID: 34358319 PMCID: PMC8421206 DOI: 10.1093/nar/gkab657] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 07/10/2021] [Accepted: 07/23/2021] [Indexed: 01/01/2023] Open
Abstract
Transcriptional regulation by Wnt signalling is primarily thought to be accomplished by a complex of β-catenin and TCF family transcription factors (TFs). Although numerous studies have suggested that additional TFs play roles in regulating Wnt target genes, their mechanisms of action have not been investigated in detail. We characterised a Wnt-responsive element (WRE) downstream of the Wnt target gene Axin2 and found that TCFs and Caudal type homeobox (CDX) proteins were required for its activation. Using a new separation-of-function TCF mutant, we found that WRE activity requires the formation of a TCF/CDX complex. Our systematic mutagenesis of this enhancer identified other sequences essential for activation by Wnt signalling, including several copies of a novel CAG DNA motif. Computational and experimental evidence indicates that the TCF/CDX/CAG mode of regulation is prevalent in multiple WREs. Put together, our results demonstrate the complex nature of cis- and trans- interactions required for signal-dependent enhancer activity.
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Affiliation(s)
| | - Lisheng Chen
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109 USA
| | - Peter E Burby
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109 USA
| | - Ken M Cadigan
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109 USA
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13
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Jindal GA, Farley EK. Enhancer grammar in development, evolution, and disease: dependencies and interplay. Dev Cell 2021; 56:575-587. [PMID: 33689769 PMCID: PMC8462829 DOI: 10.1016/j.devcel.2021.02.016] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 02/15/2021] [Accepted: 02/16/2021] [Indexed: 12/19/2022]
Abstract
Each language has standard books describing that language's grammatical rules. Biologists have searched for similar, albeit more complex, principles relating enhancer sequence to gene expression. Here, we review the literature on enhancer grammar. We introduce dependency grammar, a model where enhancers encode information based on dependencies between enhancer features shaped by mechanistic, evolutionary, and biological constraints. Classifying enhancers based on the types of dependencies may identify unifying principles relating enhancer sequence to gene expression. Such rules would allow us to read the instructions for development within genomes and pinpoint causal enhancer variants underlying disease and evolutionary changes.
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Affiliation(s)
- Granton A Jindal
- Division of Cardiology, Department of Medicine, University of California San Diego, La Jolla, CA 92093, USA; Division of Biological Sciences, Section of Molecular Biology, University of California San Diego, La Jolla, CA 92093, USA
| | - Emma K Farley
- Division of Cardiology, Department of Medicine, University of California San Diego, La Jolla, CA 92093, USA; Division of Biological Sciences, Section of Molecular Biology, University of California San Diego, La Jolla, CA 92093, USA.
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14
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Avsec Ž, Weilert M, Shrikumar A, Krueger S, Alexandari A, Dalal K, Fropf R, McAnany C, Gagneur J, Kundaje A, Zeitlinger J. Base-resolution models of transcription-factor binding reveal soft motif syntax. Nat Genet 2021; 53:354-366. [PMID: 33603233 PMCID: PMC8812996 DOI: 10.1038/s41588-021-00782-6] [Citation(s) in RCA: 233] [Impact Index Per Article: 77.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Accepted: 01/07/2021] [Indexed: 01/30/2023]
Abstract
The arrangement (syntax) of transcription factor (TF) binding motifs is an important part of the cis-regulatory code, yet remains elusive. We introduce a deep learning model, BPNet, that uses DNA sequence to predict base-resolution chromatin immunoprecipitation (ChIP)-nexus binding profiles of pluripotency TFs. We develop interpretation tools to learn predictive motif representations and identify soft syntax rules for cooperative TF binding interactions. Strikingly, Nanog preferentially binds with helical periodicity, and TFs often cooperate in a directional manner, which we validate using clustered regularly interspaced short palindromic repeat (CRISPR)-induced point mutations. Our model represents a powerful general approach to uncover the motifs and syntax of cis-regulatory sequences in genomics data.
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Affiliation(s)
- Žiga Avsec
- Department of Informatics, Technical University of Munich, Garching, Germany,Graduate School of Quantitative Biosciences (QBM), Ludwig-Maximilians-Universität München, Munich, Germany,Currently at DeepMind, London, UK
| | - Melanie Weilert
- Stowers Institute for Medical Research, Kansas City, MO, USA
| | - Avanti Shrikumar
- Department of Computer Science, Stanford University, Stanford, CA, USA
| | - Sabrina Krueger
- Stowers Institute for Medical Research, Kansas City, MO, USA
| | - Amr Alexandari
- Department of Computer Science, Stanford University, Stanford, CA, USA
| | - Khyati Dalal
- Stowers Institute for Medical Research, Kansas City, MO, USA,The University of Kansas Medical Center, Kansas City, KS, USA
| | - Robin Fropf
- Stowers Institute for Medical Research, Kansas City, MO, USA
| | - Charles McAnany
- Stowers Institute for Medical Research, Kansas City, MO, USA
| | - Julien Gagneur
- Department of Informatics, Technical University of Munich, Garching, Germany
| | - Anshul Kundaje
- Department of Computer Science, Stanford University, Stanford, CA, USA,Department of Genetics, Stanford University, Stanford, CA, USA,correspondence: ,
| | - Julia Zeitlinger
- Stowers Institute for Medical Research, Kansas City, MO, USA,The University of Kansas Medical Center, Kansas City, KS, USA,correspondence: ,
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15
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Le Poul Y, Xin Y, Ling L, Mühling B, Jaenichen R, Hörl D, Bunk D, Harz H, Leonhardt H, Wang Y, Osipova E, Museridze M, Dharmadhikari D, Murphy E, Rohs R, Preibisch S, Prud'homme B, Gompel N. Regulatory encoding of quantitative variation in spatial activity of a Drosophila enhancer. SCIENCE ADVANCES 2020; 6:6/49/eabe2955. [PMID: 33268361 PMCID: PMC7821883 DOI: 10.1126/sciadv.abe2955] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Accepted: 10/20/2020] [Indexed: 06/12/2023]
Abstract
Developmental enhancers control the expression of genes prefiguring morphological patterns. The activity of an enhancer varies among cells of a tissue, but collectively, expression levels in individual cells constitute a spatial pattern of gene expression. How the spatial and quantitative regulatory information is encoded in an enhancer sequence is elusive. To link spatial pattern and activity levels of an enhancer, we used systematic mutations of the yellow spot enhancer, active in developing Drosophila wings, and tested their effect in a reporter assay. Moreover, we developed an analytic framework based on the comprehensive quantification of spatial reporter activity. We show that the quantitative enhancer activity results from densely packed regulatory information along the sequence, and that a complex interplay between activators and multiple tiers of repressors carves the spatial pattern. Our results shed light on how an enhancer reads and integrates trans-regulatory landscape information to encode a spatial quantitative pattern.
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Affiliation(s)
- Yann Le Poul
- Evolutionary Ecology, Ludwig-Maximilians Universität München, Fakultät für Biologie, Biozentrum, Grosshaderner Strasse 2, 82152 Planegg-Martinsried, Germany
| | - Yaqun Xin
- Evolutionary Ecology, Ludwig-Maximilians Universität München, Fakultät für Biologie, Biozentrum, Grosshaderner Strasse 2, 82152 Planegg-Martinsried, Germany
| | - Liucong Ling
- Evolutionary Ecology, Ludwig-Maximilians Universität München, Fakultät für Biologie, Biozentrum, Grosshaderner Strasse 2, 82152 Planegg-Martinsried, Germany
| | - Bettina Mühling
- Evolutionary Ecology, Ludwig-Maximilians Universität München, Fakultät für Biologie, Biozentrum, Grosshaderner Strasse 2, 82152 Planegg-Martinsried, Germany
| | - Rita Jaenichen
- Evolutionary Ecology, Ludwig-Maximilians Universität München, Fakultät für Biologie, Biozentrum, Grosshaderner Strasse 2, 82152 Planegg-Martinsried, Germany
| | - David Hörl
- Human Biology and Bioimaging, Ludwig-Maximilians Universität München, Fakultät für Biologie, Biozentrum, Grosshaderner Strasse 2, 82152 Planegg-Martinsried, Germany
| | - David Bunk
- Human Biology and Bioimaging, Ludwig-Maximilians Universität München, Fakultät für Biologie, Biozentrum, Grosshaderner Strasse 2, 82152 Planegg-Martinsried, Germany
| | - Hartmann Harz
- Human Biology and Bioimaging, Ludwig-Maximilians Universität München, Fakultät für Biologie, Biozentrum, Grosshaderner Strasse 2, 82152 Planegg-Martinsried, Germany
| | - Heinrich Leonhardt
- Human Biology and Bioimaging, Ludwig-Maximilians Universität München, Fakultät für Biologie, Biozentrum, Grosshaderner Strasse 2, 82152 Planegg-Martinsried, Germany
| | - Yingfei Wang
- Quantitative and Computational Biology, Departments of Biological Sciences, Chemistry, Physics and Astronomy, and Computer Science, University of Southern California, Los Angeles, CA 90089, USA
| | - Elena Osipova
- Evolutionary Ecology, Ludwig-Maximilians Universität München, Fakultät für Biologie, Biozentrum, Grosshaderner Strasse 2, 82152 Planegg-Martinsried, Germany
| | - Mariam Museridze
- Evolutionary Ecology, Ludwig-Maximilians Universität München, Fakultät für Biologie, Biozentrum, Grosshaderner Strasse 2, 82152 Planegg-Martinsried, Germany
| | - Deepak Dharmadhikari
- Evolutionary Ecology, Ludwig-Maximilians Universität München, Fakultät für Biologie, Biozentrum, Grosshaderner Strasse 2, 82152 Planegg-Martinsried, Germany
| | - Eamonn Murphy
- Evolutionary Ecology, Ludwig-Maximilians Universität München, Fakultät für Biologie, Biozentrum, Grosshaderner Strasse 2, 82152 Planegg-Martinsried, Germany
| | - Remo Rohs
- Quantitative and Computational Biology, Departments of Biological Sciences, Chemistry, Physics and Astronomy, and Computer Science, University of Southern California, Los Angeles, CA 90089, USA
| | - Stephan Preibisch
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Robert-Rössle-Str. 10, 13092 Berlin, Germany
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Benjamin Prud'homme
- Aix-Marseille Université, CNRS, IBDM, Institut de Biologie du Développement de Marseille, Campus de Luminy Case 907, 13288 Marseille Cedex 9, France.
| | - Nicolas Gompel
- Evolutionary Ecology, Ludwig-Maximilians Universität München, Fakultät für Biologie, Biozentrum, Grosshaderner Strasse 2, 82152 Planegg-Martinsried, Germany.
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16
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Chen L, Capra JA. Learning and interpreting the gene regulatory grammar in a deep learning framework. PLoS Comput Biol 2020; 16:e1008334. [PMID: 33137083 PMCID: PMC7660921 DOI: 10.1371/journal.pcbi.1008334] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 11/12/2020] [Accepted: 09/12/2020] [Indexed: 12/12/2022] Open
Abstract
Deep neural networks (DNNs) have achieved state-of-the-art performance in identifying gene regulatory sequences, but they have provided limited insight into the biology of regulatory elements due to the difficulty of interpreting the complex features they learn. Several models of how combinatorial binding of transcription factors, i.e. the regulatory grammar, drives enhancer activity have been proposed, ranging from the flexible TF billboard model to the stringent enhanceosome model. However, there is limited knowledge of the prevalence of these (or other) sequence architectures across enhancers. Here we perform several hypothesis-driven analyses to explore the ability of DNNs to learn the regulatory grammar of enhancers. We created synthetic datasets based on existing hypotheses about combinatorial transcription factor binding site (TFBS) patterns, including homotypic clusters, heterotypic clusters, and enhanceosomes, from real TF binding motifs from diverse TF families. We then trained deep residual neural networks (ResNets) to model the sequences under a range of scenarios that reflect real-world multi-label regulatory sequence prediction tasks. We developed a gradient-based unsupervised clustering method to extract the patterns learned by the ResNet models. We demonstrated that simulated regulatory grammars are best learned in the penultimate layer of the ResNets, and the proposed method can accurately retrieve the regulatory grammar even when there is heterogeneity in the enhancer categories and a large fraction of TFBS outside of the regulatory grammar. However, we also identify common scenarios where ResNets fail to learn simulated regulatory grammars. Finally, we applied the proposed method to mouse developmental enhancers and were able to identify the components of a known heterotypic TF cluster. Our results provide a framework for interpreting the regulatory rules learned by ResNets, and they demonstrate that the ability and efficiency of ResNets in learning the regulatory grammar depends on the nature of the prediction task.
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Affiliation(s)
- Ling Chen
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, United States of America
| | - John A. Capra
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, United States of America
- Vanderbilt Genetics Institute and Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, TN, United States of America
- Department of Computer Science, Vanderbilt University, Nashville, TN, United States of America
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17
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Abstract
Key discoveries in Drosophila have shaped our understanding of cellular "enhancers." With a special focus on the fly, this chapter surveys properties of these adaptable cis-regulatory elements, whose actions are critical for the complex spatial/temporal transcriptional regulation of gene expression in metazoa. The powerful combination of genetics, molecular biology, and genomics available in Drosophila has provided an arena in which the developmental role of enhancers can be explored. Enhancers are characterized by diverse low- or high-throughput assays, which are challenging to interpret, as not all of these methods of identifying enhancers produce concordant results. As a model metazoan, the fly offers important advantages to comprehensive analysis of the central functions that enhancers play in gene expression, and their critical role in mediating the production of phenotypes from genotype and environmental inputs. A major challenge moving forward will be obtaining a quantitative understanding of how these cis-regulatory elements operate in development and disease.
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Affiliation(s)
- Stephen Small
- Department of Biology, Developmental Systems Training Program, New York University, 10003 and
| | - David N Arnosti
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824
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18
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Peter IS. The function of architecture and logic in developmental gene regulatory networks. Curr Top Dev Biol 2020; 139:267-295. [PMID: 32450963 DOI: 10.1016/bs.ctdb.2020.04.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
An important contribution of systems biology is the insight that biological systems depend on the function of molecular interactions and not just on individual molecules. System level mechanisms are particularly important in the development of animals and plants which depends not just on transcription factors and signaling molecules, but also on regulatory circuits and gene regulatory networks (GRNs). However, since GRNs consist of transcription factors, it can be challenging to assess the function of regulatory circuits independently of the function of regulatory factors. The comparison of different GRNs offers a way to do so and leads to several observations. First, similar regulatory circuits operate in various developmental contexts and in different species, and frequently, these circuits are associated with similar developmental functions. Second, given regulatory circuits are often used at particular positions within the GRN hierarchy. Third, in some GRNs, regulatory circuits are organized in a particular order in respect to each other. And fourth, the evolution of GRNs occurs not just by co-option of regulatory genes but also by rewiring of regulatory linkages between conserved regulatory genes, indicating that the organization of interactions is important. Thus, even though in most instances the function of regulatory circuits remains to be discovered, it becomes evident that the architecture and logic of GRNs are functionally important for the control of genome activity and for the specification of the body plan.
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Affiliation(s)
- Isabelle S Peter
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States.
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19
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Red Light/Green Light, a Dual Fluorescent Protein Reporter System To Study Enhancer-Promoter Specificity in Drosophila. G3-GENES GENOMES GENETICS 2020; 10:985-997. [PMID: 31900331 PMCID: PMC7056976 DOI: 10.1534/g3.119.401033] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Enhancers activate gene transcription in spatial and temporal patterns by interactions with gene promoters. These elements typically reside distal to their target promoter, with which they must interact selectively. Additional elements may contribute to enhancer-promoter specificity, including remote control element sequences within enhancers, tethering elements near promoters, and insulator/boundary elements that disrupt off-target interactions. However, few of these elements have been mapped, and as a result, the mechanisms by which these elements interact remain poorly understood. One impediment is their method of study, namely reporter transgenes in which enhancers are placed adjacent to a heterologous promoter, which may circumvent mechanisms controlling enhancer-promoter specificity and long-range interactions. Here, we report an optimized dual reporter transgene system in Drosophila melanogaster that allows the simultaneous comparison of an enhancer’s ability to activate proximal and distal fluorescent reporter genes. Testing a panel of fluorescent transgenes in vivo, we found a two-protein combination that allows simultaneous measurement with minimal detection interference. We note differences among four tested enhancers in their ability to regulate a distally placed reporter transgene. These results suggest that enhancers differ in their requirements for promoter interaction and raise important practical considerations when studying enhancer function.
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20
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Tomoyasu Y, Halfon MS. How to study enhancers in non-traditional insect models. ACTA ACUST UNITED AC 2020; 223:223/Suppl_1/jeb212241. [PMID: 32034049 DOI: 10.1242/jeb.212241] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Transcriptional enhancers are central to the function and evolution of genes and gene regulation. At the organismal level, enhancers play a crucial role in coordinating tissue- and context-dependent gene expression. At the population level, changes in enhancers are thought to be a major driving force that facilitates evolution of diverse traits. An amazing array of diverse traits seen in insect morphology, physiology and behavior has been the subject of research for centuries. Although enhancer studies in insects outside of Drosophila have been limited, recent advances in functional genomic approaches have begun to make such studies possible in an increasing selection of insect species. Here, instead of comprehensively reviewing currently available technologies for enhancer studies in established model organisms such as Drosophila, we focus on a subset of computational and experimental approaches that are likely applicable to non-Drosophila insects, and discuss the pros and cons of each approach. We discuss the importance of validating enhancer function and evaluate several possible validation methods, such as reporter assays and genome editing. Key points and potential pitfalls when establishing a reporter assay system in non-traditional insect models are also discussed. We close with a discussion of how to advance enhancer studies in insects, both by improving computational approaches and by expanding the genetic toolbox in various insects. Through these discussions, this Review provides a conceptual framework for studying the function and evolution of enhancers in non-traditional insect models.
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Affiliation(s)
| | - Marc S Halfon
- Department of Biochemistry, University at Buffalo-State University of New York, Buffalo, NY 14203, USA
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21
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Jo L, Pelletier JM, Hsu SW, Baden R, Goldberg RB, Harada JJ. Combinatorial interactions of the LEC1 transcription factor specify diverse developmental programs during soybean seed development. Proc Natl Acad Sci U S A 2020; 117:1223-1232. [PMID: 31892538 PMCID: PMC6969526 DOI: 10.1073/pnas.1918441117] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The LEAFY COTYLEDON1 (LEC1) transcription factor is a central regulator of seed development, because it controls diverse biological programs during seed development, such as embryo morphogenesis, photosynthesis, and seed maturation. To understand how LEC1 regulates different gene sets during development, we explored the possibility that LEC1 acts in combination with other transcription factors. We identified and compared genes that are directly transcriptionally regulated by ABA-RESPONSIVE ELEMENT BINDING PROTEIN3 (AREB3), BASIC LEUCINE ZIPPER67 (bZIP67), and ABA INSENSITIVE3 (ABI3) with those regulated by LEC1. We showed that LEC1 operates with specific sets of transcription factors to regulate different gene sets and, therefore, distinct developmental processes. Thus, LEC1 controls diverse processes through its combinatorial interactions with other transcription factors. DNA binding sites for the transcription factors are closely clustered in genomic regions upstream of target genes, defining cis-regulatory modules that are enriched for DNA sequence motifs that resemble sequences known to be bound by these transcription factors. Moreover, cis-regulatory modules for genes regulated by distinct transcription factor combinations are enriched for different sets of DNA motifs. Expression assays with embryo cells indicate that the enriched DNA motifs are functional cis elements that regulate transcription. Together, the results suggest that combinatorial interactions between LEC1 and other transcription factors are mediated by cis-regulatory modules containing clustered cis elements and by physical interactions that are documented to occur between the transcription factors.
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Affiliation(s)
- Leonardo Jo
- Department of Plant Biology, University of California, Davis, CA 95616
| | - Julie M Pelletier
- Department of Plant Biology, University of California, Davis, CA 95616
| | - Ssu-Wei Hsu
- Department of Plant Biology, University of California, Davis, CA 95616
| | - Russell Baden
- Department of Plant Biology, University of California, Davis, CA 95616
| | - Robert B Goldberg
- Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, CA 90095
| | - John J Harada
- Department of Plant Biology, University of California, Davis, CA 95616;
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22
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Garcia HG, Berrocal A, Kim YJ, Martini G, Zhao J. Lighting up the central dogma for predictive developmental biology. Curr Top Dev Biol 2019; 137:1-35. [PMID: 32143740 DOI: 10.1016/bs.ctdb.2019.10.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Although the last 30years have witnessed the mapping of the wiring diagrams of the gene regulatory networks that dictate cell fate and animal body plans, specific understanding building on such network diagrams that shows how DNA regulatory regions control gene expression lags far behind. These networks have yet to yield the predictive power necessary to, for example, calculate how the concentration dynamics of input transcription factors and DNA regulatory sequence prescribes output patterns of gene expression that, in turn, determine body plans themselves. Here, we argue that reaching a predictive understanding of developmental decision-making calls for an interplay between theory and experiment aimed at revealing how the regulation of the processes of the central dogma dictate network connections and how network topology guides cells toward their ultimate developmental fate. To make this possible, it is crucial to break free from the snapshot-based understanding of embryonic development facilitated by fixed-tissue approaches and embrace new technologies that capture the dynamics of developmental decision-making at the single cell level, in living embryos.
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Affiliation(s)
- Hernan G Garcia
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA, United States; Department of Physics, University of California at Berkeley, Berkeley, CA, United States; Biophysics Graduate Group, University of California at Berkeley, Berkeley, CA, United States; Quantitative Biosciences-QB3, University of California at Berkeley, Berkeley, CA, United States.
| | - Augusto Berrocal
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA, United States
| | - Yang Joon Kim
- Biophysics Graduate Group, University of California at Berkeley, Berkeley, CA, United States
| | - Gabriella Martini
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA, United States
| | - Jiaxi Zhao
- Department of Physics, University of California at Berkeley, Berkeley, CA, United States
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Bicoid-Dependent Activation of the Target Gene hunchback Requires a Two-Motif Sequence Code in a Specific Basal Promoter. Mol Cell 2019; 75:1178-1187.e4. [PMID: 31402096 DOI: 10.1016/j.molcel.2019.06.038] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 05/14/2019] [Accepted: 06/25/2019] [Indexed: 01/08/2023]
Abstract
In complex genetic loci, individual enhancers interact most often with specific basal promoters. Here we investigate the activation of the Bicoid target gene hunchback (hb), which contains two basal promoters (P1 and P2). Early in embryogenesis, P1 is silent, while P2 is strongly activated. In vivo deletion of P2 does not cause activation of P1, suggesting that P2 contains intrinsic sequence motifs required for activation. We show that a two-motif code (a Zelda binding site plus TATA) is required and sufficient for P2 activation. Zelda sites are present in the promoters of many embryonically expressed genes, but the combination of Zelda plus TATA does not seem to be a general code for early activation or Bicoid-specific activation per se. Because Zelda sites are also found in Bicoid-dependent enhancers, we propose that simultaneous binding to both enhancers and promoters independently synchronizes chromatin accessibility and facilitates correct enhancer-promoter interactions.
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24
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Rice GR, Barmina O, Luecke D, Hu K, Arbeitman M, Kopp A. Modular tissue-specific regulation of doublesex underpins sexually dimorphic development in Drosophila. Development 2019; 146:dev178285. [PMID: 31285355 PMCID: PMC6679366 DOI: 10.1242/dev.178285] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 06/28/2019] [Indexed: 11/20/2022]
Abstract
The ability of a single genome to produce distinct and often dramatically different male and female forms is one of the wonders of animal development. In Drosophila melanogaster, most sexually dimorphic traits are controlled by sex-specific isoforms of the doublesex (dsx) transcription factor, and dsx expression is mostly limited to cells that give rise to sexually dimorphic traits. However, it is unknown how this mosaic of sexually dimorphic and monomorphic organs arises. Here, we characterize the cis-regulatory sequences that control dsx expression in the foreleg, which contains multiple types of sex-specific sensory organs. We find that separate modular enhancers are responsible for dsx expression in each sexually dimorphic organ. Expression of dsx in the sex comb is co-regulated by two enhancers with distinct spatial and temporal specificities that are separated by a genitalia-specific enhancer. The sex comb-specific enhancer from D. willistoni, a species that primitively lacks sex combs, is not active in the foreleg. Thus, the mosaic of sexually dimorphic and monomorphic organs depends on modular regulation of dsx transcription by dedicated cell type-specific enhancers.
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Affiliation(s)
- Gavin R Rice
- Department of Evolution and Ecology, University of California-Davis, Davis, CA 95616, USA
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Olga Barmina
- Department of Evolution and Ecology, University of California-Davis, Davis, CA 95616, USA
| | - David Luecke
- Department of Evolution and Ecology, University of California-Davis, Davis, CA 95616, USA
| | - Kevin Hu
- Department of Evolution and Ecology, University of California-Davis, Davis, CA 95616, USA
| | - Michelle Arbeitman
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL 32306, USA
| | - Artyom Kopp
- Department of Evolution and Ecology, University of California-Davis, Davis, CA 95616, USA
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25
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Redundant and Cryptic Enhancer Activities of the Drosophila yellow Gene. Genetics 2019; 212:343-360. [PMID: 30842209 DOI: 10.1534/genetics.119.301985] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 02/25/2019] [Indexed: 11/18/2022] Open
Abstract
Cis-regulatory sequences known as enhancers play a key role in regulating gene expression. Evolutionary changes in these DNA sequences contribute to phenotypic evolution. The Drosophila yellow gene, which is required for pigmentation, has emerged as a model system for understanding how cis-regulatory sequences evolve, providing some of the most detailed insights available into how activities of orthologous enhancers have diverged between species. Here, we examine the evolution of yellow cis-regulatory sequences on a broader scale, by comparing the distribution and function of yellow enhancer activities throughout the 5' intergenic and intronic sequences of Drosophila melanogaster, D. pseudoobscura, and D. willistoni We find that cis-regulatory sequences driving expression in a particular tissue are not as modular as previously described, but rather have many redundant and cryptic enhancer activities distributed throughout the regions surveyed. Interestingly, cryptic enhancer activities of sequences from one species often drove patterns of expression observed in other species, suggesting that the frequent evolutionary changes in yellow expression observed among Drosophila species may be facilitated by gaining and losing repression of preexisting cis-regulatory sequences.
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26
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Devailly G, Joshi A. Insights into mammalian transcription control by systematic analysis of ChIP sequencing data. BMC Bioinformatics 2018; 19:409. [PMID: 30453943 PMCID: PMC6245581 DOI: 10.1186/s12859-018-2377-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Background Transcription regulation is a major controller of gene expression dynamics during development and disease, where transcription factors (TFs) modulate expression of genes through direct or indirect DNA interaction. ChIP sequencing has become the most widely used technique to get a genome wide view of TF occupancy in a cell type of interest, mainly due to established standard protocols and a rapid decrease in the cost of sequencing. The number of available ChIP sequencing data sets in public domain is therefore ever increasing, including data generated by individual labs together with consortia such as the ENCODE project. Results A total of 1735 ChIP-sequencing datasets in mouse and human cell types and tissues were used to perform bioinformatic analyses to unravel diverse features of transcription control. 1- We used the Heat*seq webtool to investigate global relations across the ChIP-seq samples. 2- We demonstrated that factors have a specific genomic location preferences that are, for most factors, conserved across species. 3- Promoter proximal binding of factors was more conserved across cell types while the distal binding sites are more cell type specific. 4- We identified combinations of factors preferentially acting together in a cellular context. 5- Finally, by integrating the data with disease-associated gene loci from GWAS studies, we highlight the value of this data to associate novel regulators to disease. Conclusion In summary, we demonstrate how ChIP sequencing data integration and analysis is powerful to get new insights into mammalian transcription control and demonstrate the utility of various bioinformatic tools to generate novel testable hypothesis using this public resource.
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Affiliation(s)
- Guillaume Devailly
- Division of Developmental Biology, the Roslin Institute, University of Edinburgh, Easter Bush Campus, Midlothian, EH25 9RG, UK
| | - Anagha Joshi
- Division of Developmental Biology, the Roslin Institute, University of Edinburgh, Easter Bush Campus, Midlothian, EH25 9RG, UK.
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27
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Zandvakili A, Uhl JD, Campbell I, Salomone J, Song YC, Gebelein B. The cis-regulatory logic underlying abdominal Hox-mediated repression versus activation of regulatory elements in Drosophila. Dev Biol 2018; 445:226-236. [PMID: 30468713 DOI: 10.1016/j.ydbio.2018.11.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Accepted: 11/12/2018] [Indexed: 11/19/2022]
Abstract
During development diverse transcription factor inputs are integrated by cis-regulatory modules (CRMs) to yield cell-specific gene expression. Defining how CRMs recruit the appropriate combinations of factors to either activate or repress gene expression remains a challenge. In this study, we compare and contrast the ability of two CRMs within the Drosophila embryo to recruit functional Hox transcription factor complexes. The DCRE CRM recruits Ultrabithorax (Ubx) and Abdominal-A (Abd-A) Hox complexes that include the Extradenticle (Exd) and Homothorax (Hth) transcription factors to repress the Distal-less leg selector gene, whereas the RhoA CRM selectively recruits Abd-A/Exd/Hth complexes to activate rhomboid and stimulate Epidermal Growth Factor secretion in sensory cell precursors. By swapping binding sites between these elements, we found that the RhoA Exd/Hth/Hox site configuration that mediates Abd-A specific activation can convey transcriptional repression by both Ubx and Abd-A when placed into the DCRE. We further show that the orientation and spacing of Hox sites relative to additional binding sites within the RhoA and DCRE is critical to mediate cell- and segment-specific output. These results indicate that the configuration of Exd, Hth, and Hox site within RhoA is neither Abd-A specific nor activation specific. Instead Hox specific output is largely dependent upon the presence of appropriately spaced and oriented binding sites for additional TF inputs. Taken together, these studies provide insight into the cis-regulatory logic used to generate cell-specific outputs via recruiting Hox transcription factor complexes.
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Affiliation(s)
- Arya Zandvakili
- Graduate Program in Molecular and Developmental Biology, Cincinnati Children's Hospital Research Foundation, Cincinnati, OH 45229, USA; Medical-Scientist Training Program, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
| | - Juli D Uhl
- Graduate Program in Molecular and Developmental Biology, Cincinnati Children's Hospital Research Foundation, Cincinnati, OH 45229, USA; Department of Biological Sciences, University of Cincinnati, Cincinnati, OH, USA
| | - Ian Campbell
- Department of Biomedical Engineering, University of Cincinnati, Cincinnati, OH, USA
| | - Joseph Salomone
- Graduate Program in Molecular and Developmental Biology, Cincinnati Children's Hospital Research Foundation, Cincinnati, OH 45229, USA; Medical-Scientist Training Program, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
| | - Yuntao Charlie Song
- Graduate Program in Molecular and Developmental Biology, Cincinnati Children's Hospital Research Foundation, Cincinnati, OH 45229, USA
| | - Brian Gebelein
- Division of Developmental Biology, Cincinnati Children's Hospital, 3333 Burnet Ave, MLC 7007, Cincinnati, OH 45229, USA; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA.
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28
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Hope CM, Webber JL, Tokamov SA, Rebay I. Tuned polymerization of the transcription factor Yan limits off-DNA sequestration to confer context-specific repression. eLife 2018; 7:37545. [PMID: 30412049 PMCID: PMC6226293 DOI: 10.7554/elife.37545] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 10/22/2018] [Indexed: 01/08/2023] Open
Abstract
During development, transcriptional complexes at enhancers regulate gene expression in complex spatiotemporal patterns. To achieve robust expression without spurious activation, the affinity and specificity of transcription factor–DNA interactions must be precisely balanced. Protein–protein interactions among transcription factors are also critical, yet how their affinities impact enhancer output is not understood. The Drosophila transcription factor Yan provides a well-suited model to address this, as its function depends on the coordinated activities of two independent and essential domains: the DNA-binding ETS domain and the self-associating SAM domain. To explore how protein–protein affinity influences Yan function, we engineered mutants that increase SAM affinity over four orders of magnitude. This produced a dramatic subcellular redistribution of Yan into punctate structures, reduced repressive output and compromised survival. Cell-type specification and genetic interaction defects suggest distinct requirements for polymerization in different regulatory decisions. We conclude that tuned protein–protein interactions enable the dynamic spectrum of complexes that are required for proper regulation.
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Affiliation(s)
- C Matthew Hope
- Department of Biochemistry and Molecular Biophysics, University of Chicago, Chicago, United States
| | - Jemma L Webber
- Ben May Department for Cancer Research, University of Chicago, Chicago, United States
| | - Sherzod A Tokamov
- Committee on Development, Regeneration, and Stem Cell Biology, University of Chicago, Chicago, United States
| | - Ilaria Rebay
- Ben May Department for Cancer Research, University of Chicago, Chicago, United States.,Committee on Development, Regeneration, and Stem Cell Biology, University of Chicago, Chicago, United States
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29
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Ross J, Kuzin A, Brody T, Odenwald WF. Mutational analysis of a Drosophila neuroblast enhancer governing nubbin expression during CNS development. Genesis 2018; 56:e23237. [PMID: 30005136 PMCID: PMC6175444 DOI: 10.1002/dvg.23237] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 06/07/2018] [Accepted: 06/22/2018] [Indexed: 11/17/2022]
Abstract
While developmental studies of Drosophila neural stem cell lineages have identified transcription factors (TFs) important to cell identity decisions, currently only an incomplete understanding exists of the cis‐regulatory elements that control the dynamic expression of these TFs. Our previous studies have identified multiple enhancers that regulate the POU‐domain TF paralogs nubbin and pdm‐2 genes. Evolutionary comparative analysis of these enhancers reveals that they each contain multiple conserved sequence blocks (CSBs) that span TF DNA‐binding sites for known regulators of neuroblast (NB) gene expression in addition to novel sequences. This study functionally analyzes the conserved DNA sequence elements within a NB enhancer located within the nubbin gene and highlights a high level of complexity underlying enhancer structure. Mutational analysis has revealed CSBs that are important for enhancer activation and silencing in the developing CNS. We have also observed that adjusting the number and relative positions of the TF binding sites within these CSBs alters enhancer function.
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Affiliation(s)
- Jermaine Ross
- Neural Cell-Fate Determinants Section, NINDS, NIH, Bethesda, Maryland
| | - Alexander Kuzin
- Neural Cell-Fate Determinants Section, NINDS, NIH, Bethesda, Maryland
| | - Thomas Brody
- Neural Cell-Fate Determinants Section, NINDS, NIH, Bethesda, Maryland
| | - Ward F Odenwald
- Neural Cell-Fate Determinants Section, NINDS, NIH, Bethesda, Maryland
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30
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Abstract
A growing body of evidence shows that gene expression in multicellular organisms is controlled by the combinatorial function of multiple transcription factors. This indicates that not the individual transcription factors or signaling molecules, but the combination of expressed regulatory molecules, the regulatory state, should be viewed as the functional unit in gene regulation. Here, I discuss the concept of the regulatory state and its proposed role in the genome-wide control of gene expression. Recent analyses of regulatory gene expression in sea urchin embryos have been instrumental for solving the genomic control of cell fate specification in this system. Some of the approaches that were used to determine the expression of regulatory states during sea urchin embryogenesis are reviewed. Significant developmental changes in regulatory state expression leading to the distinct specification of cell fates are regulated by gene regulatory network circuits. How these regulatory state transitions are encoded in the genome is illuminated using the sea urchin endoderm-mesoderms cell fate decision circuit as an example. These observations highlight the importance of considering developmental gene regulation, and the function of individual transcription factors, in the context of regulatory states.
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31
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Lettice LA, Devenney P, De Angelis C, Hill RE. The Conserved Sonic Hedgehog Limb Enhancer Consists of Discrete Functional Elements that Regulate Precise Spatial Expression. Cell Rep 2018; 20:1396-1408. [PMID: 28793263 PMCID: PMC5561167 DOI: 10.1016/j.celrep.2017.07.037] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2016] [Revised: 05/17/2017] [Accepted: 07/13/2017] [Indexed: 12/21/2022] Open
Abstract
Expression of sonic hedgehog (Shh) in the limb bud is regulated by an enhancer called the zone of polarizing activity regulatory sequence (ZRS), which, in evolution, belongs to an ancient group of highly conserved cis regulators found in all classes of vertebrates. Here, we examined the endogenous ZRS in mice, using genome editing to establish the relationship between enhancer composition and embryonic phenotype. We show that enhancer activity is a consolidation of distinct activity domains. Spatial restriction of Shh expression is mediated by a discrete repressor module, whereas levels of gene expression are controlled by large overlapping domains containing varying numbers of HOXD binding sites. The number of HOXD binding sites regulates expression levels incrementally. Substantial portions of conserved sequence are dispensable, indicating the presence of sequence redundancy. We propose a collective model for enhancer activity in which function is an integration of discrete expression activities and redundant components that drive robust expression. The ancient vertebrate enhancer, the ZRS, shows sequence plasticity Discrete regulatory activities are assigned to specific sites in the enhancer The number of HOXD binding sites determines the level of Shh expression Robust expression is a collective of regulatory and redundant information
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Affiliation(s)
- Laura A Lettice
- MRC Human Genetics Unit, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK
| | - Paul Devenney
- MRC Human Genetics Unit, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK
| | - Carlo De Angelis
- MRC Human Genetics Unit, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK
| | - Robert E Hill
- MRC Human Genetics Unit, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK.
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32
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Zandvakili A, Campbell I, Gutzwiller LM, Weirauch MT, Gebelein B. Degenerate Pax2 and Senseless binding motifs improve detection of low-affinity sites required for enhancer specificity. PLoS Genet 2018; 14:e1007289. [PMID: 29617378 PMCID: PMC5902045 DOI: 10.1371/journal.pgen.1007289] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Revised: 04/16/2018] [Accepted: 03/05/2018] [Indexed: 12/01/2022] Open
Abstract
Cells use thousands of regulatory sequences to recruit transcription factors (TFs) and produce specific transcriptional outcomes. Since TFs bind degenerate DNA sequences, discriminating functional TF binding sites (TFBSs) from background sequences represents a significant challenge. Here, we show that a Drosophila regulatory element that activates Epidermal Growth Factor signaling requires overlapping, low-affinity TFBSs for competing TFs (Pax2 and Senseless) to ensure cell- and segment-specific activity. Testing available TF binding models for Pax2 and Senseless, however, revealed variable accuracy in predicting such low-affinity TFBSs. To better define parameters that increase accuracy, we developed a method that systematically selects subsets of TFBSs based on predicted affinity to generate hundreds of position-weight matrices (PWMs). Counterintuitively, we found that degenerate PWMs produced from datasets depleted of high-affinity sequences were more accurate in identifying both low- and high-affinity TFBSs for the Pax2 and Senseless TFs. Taken together, these findings reveal how TFBS arrangement can be constrained by competition rather than cooperativity and that degenerate models of TF binding preferences can improve identification of biologically relevant low affinity TFBSs. While all cells in an organism share a common genome, each cell type must express the appropriate combination of genes needed for its specific function. Cells activate and repress different parts of the genome using transcription factor proteins that bind regulatory regions known as enhancers. We currently have an incomplete view of how enhancers recruit transcription factors to yield accurate gene activation and repression. This problem is complicated by the fact that most animals contain over a thousand different transcription factors, and each can generally bind multiple DNA sequences. Thus, it is difficult to predict which transcription factors interact with which enhancers. To gain insights into this process, we focused on determining how an enhancer that activates a gene needed to make liver-like cells is regulated in a precise manner in the fruit-fly embryo. We demonstrate that the specific activity of this enhancer depends on weak and overlapping transcription factor binding sites. Furthermore, we demonstrate that computational models that include weak transcription factor interactions yield better predictive accuracy. These results shed light on how DNA sequences determine enhancer activity and the types of strategies that are most useful for predicting transcription factor binding sites in the genome.
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Affiliation(s)
- Arya Zandvakili
- Graduate Program in Molecular and Developmental Biology, Cincinnati Children's Hospital Research Foundation, Cincinnati, OH, United States of America
- Medical-Scientist Training Program, University of Cincinnati College of Medicine, Cincinnati, OH, United States of America
| | - Ian Campbell
- Division of Developmental Biology, Cincinnati Children’s Hospital, MLC, Cincinnati, OH, United States of America
| | - Lisa M. Gutzwiller
- Division of Developmental Biology, Cincinnati Children’s Hospital, MLC, Cincinnati, OH, United States of America
| | - Matthew T. Weirauch
- Division of Developmental Biology, Cincinnati Children’s Hospital, MLC, Cincinnati, OH, United States of America
- Center for Autoimmune Genomics and Etiology & Division of Biomedical Informatics, Cincinnati Children’s Hospital, MLC, Cincinnati, OH, United States of America
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, United States of America
| | - Brian Gebelein
- Division of Developmental Biology, Cincinnati Children’s Hospital, MLC, Cincinnati, OH, United States of America
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, United States of America
- * E-mail:
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33
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Lloret-Fernández C, Maicas M, Mora-Martínez C, Artacho A, Jimeno-Martín Á, Chirivella L, Weinberg P, Flames N. A transcription factor collective defines the HSN serotonergic neuron regulatory landscape. eLife 2018; 7:32785. [PMID: 29553368 PMCID: PMC5916565 DOI: 10.7554/elife.32785] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 03/16/2018] [Indexed: 01/02/2023] Open
Abstract
Cell differentiation is controlled by individual transcription factors (TFs) that together activate a selection of enhancers in specific cell types. How these combinations of TFs identify and activate their target sequences remains poorly understood. Here, we identify the cis-regulatory transcriptional code that controls the differentiation of serotonergic HSN neurons in Caenorhabditis elegans. Activation of the HSN transcriptome is directly orchestrated by a collective of six TFs. Binding site clusters for this TF collective form a regulatory signature that is sufficient for de novo identification of HSN neuron functional enhancers. Among C. elegans neurons, the HSN transcriptome most closely resembles that of mouse serotonergic neurons. Mouse orthologs of the HSN TF collective also regulate serotonergic differentiation and can functionally substitute for their worm counterparts which suggests deep homology. Our results identify rules governing the regulatory landscape of a critically important neuronal type in two species separated by over 700 million years.
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Affiliation(s)
- Carla Lloret-Fernández
- Developmental Neurobiology Unit, Instituto de Biomedicina de Valencia IBV-CSIC, Valencia, Spain
| | - Miren Maicas
- Developmental Neurobiology Unit, Instituto de Biomedicina de Valencia IBV-CSIC, Valencia, Spain
| | - Carlos Mora-Martínez
- Developmental Neurobiology Unit, Instituto de Biomedicina de Valencia IBV-CSIC, Valencia, Spain
| | - Alejandro Artacho
- Departamento de Genómica y Salud, Centro Superior de Investigación en Salud Pública, FISABIO, Valencia, Spain
| | - Ángela Jimeno-Martín
- Developmental Neurobiology Unit, Instituto de Biomedicina de Valencia IBV-CSIC, Valencia, Spain
| | - Laura Chirivella
- Developmental Neurobiology Unit, Instituto de Biomedicina de Valencia IBV-CSIC, Valencia, Spain
| | - Peter Weinberg
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University Medical Center, New York, United States
| | - Nuria Flames
- Developmental Neurobiology Unit, Instituto de Biomedicina de Valencia IBV-CSIC, Valencia, Spain
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34
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Behera V, Evans P, Face CJ, Hamagami N, Sankaranarayanan L, Keller CA, Giardine B, Tan K, Hardison RC, Shi J, Blobel GA. Exploiting genetic variation to uncover rules of transcription factor binding and chromatin accessibility. Nat Commun 2018; 9:782. [PMID: 29472540 PMCID: PMC5823854 DOI: 10.1038/s41467-018-03082-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Accepted: 01/18/2018] [Indexed: 12/13/2022] Open
Abstract
Single-nucleotide variants that underlie phenotypic variation can affect chromatin occupancy of transcription factors (TFs). To delineate determinants of in vivo TF binding and chromatin accessibility, we introduce an approach that compares ChIP-seq and DNase-seq data sets from genetically divergent murine erythroid cell lines. The impact of discriminatory single-nucleotide variants on TF ChIP signal enables definition at single base resolution of in vivo binding characteristics of nuclear factors GATA1, TAL1, and CTCF. We further develop a facile complementary approach to more deeply test the requirements of critical nucleotide positions for TF binding by combining CRISPR-Cas9-mediated mutagenesis with ChIP and targeted deep sequencing. Finally, we extend our analytical pipeline to identify nearby contextual DNA elements that modulate chromatin binding by these three TFs, and to define sequences that impact kb-scale chromatin accessibility. Combined, our approaches reveal insights into the genetic basis of TF occupancy and their interplay with chromatin features.
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Affiliation(s)
- Vivek Behera
- University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Perry Evans
- Department of Biomedical and Health Informatics, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
| | - Carolyne J Face
- Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
| | - Nicole Hamagami
- Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
| | | | | | | | - Kai Tan
- Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
| | | | - Junwei Shi
- University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Gerd A Blobel
- Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA.
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35
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Morrison CA, Chen H, Cook T, Brown S, Treisman JE. Glass promotes the differentiation of neuronal and non-neuronal cell types in the Drosophila eye. PLoS Genet 2018; 14:e1007173. [PMID: 29324767 PMCID: PMC5783423 DOI: 10.1371/journal.pgen.1007173] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 01/24/2018] [Accepted: 12/29/2017] [Indexed: 11/18/2022] Open
Abstract
Transcriptional regulators can specify different cell types from a pool of equivalent progenitors by activating distinct developmental programs. The Glass transcription factor is expressed in all progenitors in the developing Drosophila eye, and is maintained in both neuronal and non-neuronal cell types. Glass is required for neuronal progenitors to differentiate as photoreceptors, but its role in non-neuronal cone and pigment cells is unknown. To determine whether Glass activity is limited to neuronal lineages, we compared the effects of misexpressing it in neuroblasts of the larval brain and in epithelial cells of the wing disc. Glass activated overlapping but distinct sets of genes in these neuronal and non-neuronal contexts, including markers of photoreceptors, cone cells and pigment cells. Coexpression of other transcription factors such as Pax2, Eyes absent, Lozenge and Escargot enabled Glass to induce additional genes characteristic of the non-neuronal cell types. Cell type-specific glass mutations generated in cone or pigment cells using somatic CRISPR revealed autonomous developmental defects, and expressing Glass specifically in these cells partially rescued glass mutant phenotypes. These results indicate that Glass is a determinant of organ identity that acts in both neuronal and non-neuronal cells to promote their differentiation into functional components of the eye.
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Affiliation(s)
- Carolyn A. Morrison
- Skirball Institute for Biomolecular Medicine and Department of Cell Biology, NYU School of Medicine, New York, NY, United States of America
| | - Hao Chen
- Department of Cell Biology, NYU School of Medicine, New York, NY, United States of America
| | - Tiffany Cook
- Center of Molecular Medicine and Genomics and Department of Ophthalmology, Wayne State University School of Medicine, Detroit, MI, United States of America
| | - Stuart Brown
- Department of Cell Biology, NYU School of Medicine, New York, NY, United States of America
| | - Jessica E. Treisman
- Skirball Institute for Biomolecular Medicine and Department of Cell Biology, NYU School of Medicine, New York, NY, United States of America
- * E-mail:
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36
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KSHV episomes reveal dynamic chromatin loop formation with domain-specific gene regulation. Nat Commun 2018; 9:49. [PMID: 29302027 PMCID: PMC5754359 DOI: 10.1038/s41467-017-02089-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Accepted: 11/03/2017] [Indexed: 02/03/2023] Open
Abstract
The three-dimensional structure of chromatin organized by genomic loops facilitates RNA polymerase II access to distal promoters. The Kaposi's sarcoma-associated herpesvirus (KSHV) lytic transcriptional program is initiated by a single viral transactivator, K-Rta. Here we report the KSHV genomic structure and its relationship with K-Rta recruitment sites using Capture Hi-C analyses. High-resolution 3D viral genomic maps identify a number of direct physical, long-range, and dynamic genomic interactions. Mutant KSHV chromosomes harboring point mutations in the K-Rta responsive elements (RE) significantly attenuate not only the directly proximate downstream gene, but also distal gene expression in a domain-specific manner. Genomic loops increase in the presence of K-Rta, while abrogation of K-Rta binding impairs the formation of inducible genomic loops, decreases the expression of genes networked through the looping, and diminishes KSHV replication. Our study demonstrates that genomic architectural dynamics plays an essential role in herpesvirus gene expression.
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37
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Barr KA, Martinez C, Moran JR, Kim AR, Ramos AF, Reinitz J. Synthetic enhancer design by in silico compensatory evolution reveals flexibility and constraint in cis-regulation. BMC SYSTEMS BIOLOGY 2017; 11:116. [PMID: 29187214 PMCID: PMC5708098 DOI: 10.1186/s12918-017-0485-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 11/09/2017] [Indexed: 11/12/2022]
Abstract
BACKGROUND Models that incorporate specific chemical mechanisms have been successful in describing the activity of Drosophila developmental enhancers as a function of underlying transcription factor binding motifs. Despite this, the minimum set of mechanisms required to reconstruct an enhancer from its constituent parts is not known. Synthetic biology offers the potential to test the sufficiency of known mechanisms to describe the activity of enhancers, as well as to uncover constraints on the number, order, and spacing of motifs. RESULTS Using a functional model and in silico compensatory evolution, we generated putative synthetic even-skipped stripe 2 enhancers with varying degrees of similarity to the natural enhancer. These elements represent the evolutionary trajectories of the natural stripe 2 enhancer towards two synthetic enhancers designed ab initio. In the first trajectory, spatially regulated expression was maintained, even after more than a third of binding sites were lost. In the second, sequences with high similarity to the natural element did not drive expression, but a highly diverged sequence about half the length of the minimal stripe 2 enhancer drove ten times greater expression. Additionally, homotypic clusters of Zelda or Stat92E motifs, but not Bicoid, drove expression in developing embryos. CONCLUSIONS Here, we present a functional model of gene regulation to test the degree to which the known transcription factors and their interactions explain the activity of the Drosophila even-skipped stripe 2 enhancer. Initial success in the first trajectory showed that the gene regulation model explains much of the function of the stripe 2 enhancer. Cases where expression deviated from prediction indicates that undescribed factors likely act to modulate expression. We also showed that activation driven Bicoid and Hunchback is highly sensitive to spatial organization of binding motifs. In contrast, Zelda and Stat92E drive expression from simple homotypic clusters, suggesting that activation driven by these factors is less constrained. Collectively, the 40 sequences generated in this work provides a powerful training set for building future models of gene regulation.
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Affiliation(s)
- Kenneth A Barr
- Committee on Genetics, Genomics, and Systems Biology, University of Chicago, Zoology 111, 1101 E 57th St, Chicago, 60637, Illinois, USA.
- Department of Ecology and Evolution, The University of Chicago, Chicago, 60637, Illinois, USA.
| | - Carlos Martinez
- Department Biochemistry and Molecular Genetics, Northwestern University, Chicago, 60611, Illinois, USA
| | - Jennifer R Moran
- Department Human Genetics, The University of Chicago, Chicago, 60637, Illinois, USA
- Institute for Genomics & Systems Biology, The University of Chicago, Chicago, 60637, Illinois, USA
| | - Ah-Ram Kim
- School of Life Science, Handong Global University, Pohang, 37554, Gyeongbuk, South Korea
| | - Alexandre F Ramos
- Departamento de Radiologia - Faculdade de Medicina, Universidade de São Paulo & Instituto do Câncer do Estado de São Paulo, São Paulo, SP CEP, 05403-911, Brazil
- Escola de Artes, Ciências e Humanidades & Núcleo de Estudos Interdisciplinares em Sistemas Complexos, Universidade de São Paulo, Av. Arlindo Béttio, São Paulo, 1000 CEP 03828-000, SP, Brazil
| | - John Reinitz
- Committee on Genetics, Genomics, and Systems Biology, University of Chicago, Zoology 111, 1101 E 57th St, Chicago, 60637, Illinois, USA
- Department of Ecology and Evolution, The University of Chicago, Chicago, 60637, Illinois, USA
- Institute for Genomics & Systems Biology, The University of Chicago, Chicago, 60637, Illinois, USA
- Department Statistics, The University of Chicago, 5747 S. Ellis Avenue Jones 312, Chicago, 60637, IL, USA
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38
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Dalal CK, Johnson AD. How transcription circuits explore alternative architectures while maintaining overall circuit output. Genes Dev 2017; 31:1397-1405. [PMID: 28860157 PMCID: PMC5588923 DOI: 10.1101/gad.303362.117] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
This review by Dalal and Johnson focuses on the evolutionary rewiring of transcription regulators and the conservation of patterns of gene expression. They describe how preservation of gene expression patterns in the wake of extensive rewiring is a general feature of transcription circuit evolution. Transcription regulators bind to cis-regulatory sequences and thereby control the expression of target genes. While transcription regulators and the target genes that they regulate are often deeply conserved across species, the connections between the two change extensively over evolutionary timescales. In this review, we discuss case studies where, despite this extensive evolutionary rewiring, the resulting patterns of gene expression are preserved. We also discuss in silico models that reach the same general conclusions and provide additional insights into how this process occurs. Together, these approaches make a strong case that the preservation of gene expression patterns in the wake of extensive rewiring is a general feature of transcription circuit evolution.
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Affiliation(s)
- Chiraj K Dalal
- Department of Microbiology and Immunology, University of California at San Francisco, San Francisco, California 94158, USA
| | - Alexander D Johnson
- Department of Microbiology and Immunology, University of California at San Francisco, San Francisco, California 94158, USA.,Department of Biochemistry and Biophysics, University of California at San Francisco, San Francisco, California 94158, USA
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39
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Brown AJ, Gibson SJ, Hatton D, James DC. In silico design of context-responsive mammalian promoters with user-defined functionality. Nucleic Acids Res 2017; 45:10906-10919. [PMID: 28977454 PMCID: PMC5737543 DOI: 10.1093/nar/gkx768] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 08/22/2017] [Indexed: 12/19/2022] Open
Abstract
Comprehensive de novo-design of complex mammalian promoters is restricted by unpredictable combinatorial interactions between constituent transcription factor regulatory elements (TFREs). In this study, we show that modular binding sites that do not function cooperatively can be identified by analyzing host cell transcription factor expression profiles, and subsequently testing cognate TFRE activities in varying homotypic and heterotypic promoter architectures. TFREs that displayed position-insensitive, additive function within a specific expression context could be rationally combined together in silico to create promoters with highly predictable activities. As TFRE order and spacing did not affect the performance of these TFRE-combinations, compositions could be specifically arranged to preclude the formation of undesirable sequence features. This facilitated simple in silico-design of promoters with context-required, user-defined functionalities. To demonstrate this, we de novo-created promoters for biopharmaceutical production in CHO cells that exhibited precisely designed activity dynamics and long-term expression-stability, without causing observable retroactive effects on cellular performance. The design process described can be utilized for applications requiring context-responsive, customizable promoter function, particularly where co-expression of synthetic TFs is not suitable. Although the synthetic promoter structure utilized does not closely resemble native mammalian architectures, our findings also provide additional support for a flexible billboard model of promoter regulation.
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Affiliation(s)
- Adam J Brown
- Department of Chemical and Biological Engineering, University of Sheffield, Mappin St., Sheffield S1 3JD, UK
| | - Suzanne J Gibson
- Biopharmaceutical Development, MedImmune, Cambridge CB21 6GH, UK
| | - Diane Hatton
- Biopharmaceutical Development, MedImmune, Cambridge CB21 6GH, UK
| | - David C James
- Department of Chemical and Biological Engineering, University of Sheffield, Mappin St., Sheffield S1 3JD, UK
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40
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The Canonical Notch Signaling Pathway: Structural and Biochemical Insights into Shape, Sugar, and Force. Dev Cell 2017; 41:228-241. [PMID: 28486129 DOI: 10.1016/j.devcel.2017.04.001] [Citation(s) in RCA: 252] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Revised: 03/04/2017] [Accepted: 04/03/2017] [Indexed: 02/07/2023]
Abstract
The Notch signaling pathway relies on a proteolytic cascade to release its transcriptionally active intracellular domain, on force to unfold a protective domain and permit proteolysis, on extracellular domain glycosylation to tune the forces exerted by endocytosed ligands, and on a motley crew of nuclear proteins, chromatin modifiers, ubiquitin ligases, and a few kinases to regulate activity and half-life. Herein we provide a review of recent molecular insights into how Notch signals are triggered and how cell shape affects these events, and we use the new insights to illuminate a few perplexing observations.
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41
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Vermunt MW, Creyghton MP. Transcriptional Dynamics at Brain Enhancers: from Functional Specialization to Neurodegeneration. Curr Neurol Neurosci Rep 2017; 16:94. [PMID: 27628759 PMCID: PMC5023742 DOI: 10.1007/s11910-016-0689-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Over the last decade, the noncoding part of the genome has been shown to harbour thousands of cis-regulatory elements, such as enhancers, that activate well-defined gene expression programs. Driven by the development of numerous techniques, many of these elements are now identified in multiple tissues and cell types, and their characteristics as well as importance in development and disease are becoming increasingly clear. Here, we provide an overview of the insights that were gained from the analysis of noncoding gene regulatory elements in the brain and describe their potential contribution to cell type specialization, brain function and neurodegenerative disease.
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Affiliation(s)
- Marit W Vermunt
- Hubrecht Institute-KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584CT, Utrecht, The Netherlands
| | - Menno P Creyghton
- Hubrecht Institute-KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584CT, Utrecht, The Netherlands.
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42
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Maricque BB, Dougherty JD, Cohen BA. A genome-integrated massively parallel reporter assay reveals DNA sequence determinants of cis-regulatory activity in neural cells. Nucleic Acids Res 2017; 45:e16. [PMID: 28204611 PMCID: PMC5389540 DOI: 10.1093/nar/gkw942] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Revised: 10/05/2016] [Accepted: 10/11/2016] [Indexed: 11/12/2022] Open
Abstract
Recent large-scale genomics efforts to characterize the cis-regulatory sequences that orchestrate genome-wide expression patterns have produced impressive catalogues of putative regulatory elements. Most of these sequences have not been functionally tested, and our limited understanding of the non-coding genome prevents us from predicting which sequences are bona fide cis-regulatory elements. Recently, massively parallel reporter assays (MPRAs) have been deployed to measure the activity of putative cis-regulatory sequences in several biological contexts, each with specific advantages and distinct limitations. We developed LV-MPRA, a novel lentiviral-based, massively parallel reporter gene assay, to study the function of genome-integrated regulatory elements in any mammalian cell type; thus, making it possible to apply MPRAs in more biologically relevant contexts. We measured the activity of 2,600 sequences in U87 glioblastoma cells and human neural progenitor cells (hNPCs) and explored how regulatory activity is encoded in DNA sequence. We demonstrate that LV-MPRA can be applied to estimate the effects of local DNA sequence and regional chromatin on regulatory activity. Our data reveal that primary DNA sequence features, such as GC content and dinucleotide composition, accurately distinguish sequences with high activity from sequences with low activity in a full chromosomal context, and may also function in combination with different transcription factor binding sites to determine cell type specificity. We conclude that LV-MPRA will be an important tool for identifying cis-regulatory elements and stimulating new understanding about how the non-coding genome encodes information.
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Affiliation(s)
- Brett B. Maricque
- Center for Genome Sciences and Systems Biology, Washington University School of Medicine, Saint Louis, MO 63108, USA
- Department of Genetics, Washington University School of Medicine, Saint Louis, MO 63108, USA
| | - Joseph D. Dougherty
- Department of Genetics, Washington University School of Medicine, Saint Louis, MO 63108, USA
- Department of Psychiatry, Washington University School of Medicine, Saint Louis, MO 63108, USA
| | - Barak A. Cohen
- Center for Genome Sciences and Systems Biology, Washington University School of Medicine, Saint Louis, MO 63108, USA
- Department of Genetics, Washington University School of Medicine, Saint Louis, MO 63108, USA
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43
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Rainbow Enhancers Regulate Restrictive Transcription in Teleost Green, Red, and Blue Cones. J Neurosci 2017; 37:2834-2848. [PMID: 28193687 DOI: 10.1523/jneurosci.3421-16.2017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Revised: 12/31/2016] [Accepted: 01/27/2017] [Indexed: 01/24/2023] Open
Abstract
Photoreceptor-specific transcription of individual genes collectively constitutes the transcriptional profile that orchestrates the structural and functional characteristics of each photoreceptor type. It is challenging, however, to study the transcriptional specificity of individual photoreceptor genes because each gene's distinct spatiotemporal transcription patterns are determined by the unique interactions between a specific set of transcription factors and the gene's own cis-regulatory elements (CREs), which remain unknown for most of the genes. For example, it is unknown what CREs underlie the zebrafish mpp5bponli (ponli) and crumbs2b (crb2b) apical polarity genes' restrictive transcription in the red, green, and blue (RGB) cones in the retina, but not in other retinal cell types. Here we show that the intronic enhancers of both the ponli and crb2b genes are conserved among teleost species and that they share sequence motifs that are critical for RGB cone-specific transcription. Given their similarities in sequences and functions, we name the ponli and crb2b enhancers collectively rainbow enhancers. Rainbow enhancers may represent a cis-regulatory mechanism to turn on a group of genes that are commonly and restrictively expressed in RGB cones, which largely define the beginning of the color vision pathway.SIGNIFICANCE STATEMENT Dim-light achromatic vision and bright-light color vision are initiated in rod and several types of cone photoreceptors, respectively; these photoreceptors are structurally distinct from each other. In zebrafish, although quite different from rods and UV cones, RGB cones (red, green, and blue cones) are structurally similar and unite into mirror-symmetric pentamers (G-R-B-R-G) by adhesion. This structural commonality and unity suggest that a set of genes is commonly expressed only in RGB cones but not in other cells. Here, we report that the rainbow enhancers activate RGB cone-specific transcription of the ponli and crb2b genes. This study provides a starting point to study how RGB cone-specific transcription defines RGB cones' distinct functions for color vision.
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44
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Reiter F, Wienerroither S, Stark A. Combinatorial function of transcription factors and cofactors. Curr Opin Genet Dev 2017; 43:73-81. [PMID: 28110180 DOI: 10.1016/j.gde.2016.12.007] [Citation(s) in RCA: 190] [Impact Index Per Article: 27.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Revised: 12/14/2016] [Accepted: 12/21/2016] [Indexed: 12/31/2022]
Abstract
Differential gene expression gives rise to the many cell types of complex organisms. Enhancers regulate transcription by binding transcription factors (TFs), which in turn recruit cofactors to activate RNA Polymerase II at core promoters. Transcriptional regulation is typically mediated by distinct combinations of TFs, enabling a relatively small number of TFs to generate a large diversity of cell types. However, how TFs achieve combinatorial enhancer control and how enhancers, enhancer-bound TFs, and the cofactors they recruit regulate RNA Polymerase II activity is not entirely clear. Here, we review how TF synergy is mediated at the level of DNA binding and after binding, the role of cofactors and the post-translational modifications they catalyze, and discuss different models of enhancer-core-promoter communication.
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Affiliation(s)
- Franziska Reiter
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus-Vienna-Biocenter 1, 1030 Vienna, Austria
| | - Sebastian Wienerroither
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus-Vienna-Biocenter 1, 1030 Vienna, Austria
| | - Alexander Stark
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus-Vienna-Biocenter 1, 1030 Vienna, Austria.
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45
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Evolution of New cis-Regulatory Motifs Required for Cell-Specific Gene Expression in Caenorhabditis. PLoS Genet 2016; 12:e1006278. [PMID: 27588814 PMCID: PMC5010242 DOI: 10.1371/journal.pgen.1006278] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 08/04/2016] [Indexed: 12/19/2022] Open
Abstract
Patterning of C. elegans vulval cell fates relies on inductive signaling. In this induction event, a single cell, the gonadal anchor cell, secretes LIN-3/EGF and induces three out of six competent precursor cells to acquire a vulval fate. We previously showed that this developmental system is robust to a four-fold variation in lin-3/EGF genetic dose. Here using single-molecule FISH, we find that the mean level of expression of lin-3 in the anchor cell is remarkably conserved. No change in lin-3 expression level could be detected among C. elegans wild isolates and only a low level of change—less than 30%—in the Caenorhabditis genus and in Oscheius tipulae. In C. elegans, lin-3 expression in the anchor cell is known to require three transcription factor binding sites, specifically two E-boxes and a nuclear-hormone-receptor (NHR) binding site. Mutation of any of these three elements in C. elegans results in a dramatic decrease in lin-3 expression. Yet only a single E-box is found in the Drosophilae supergroup of Caenorhabditis species, including C. angaria, while the NHR-binding site likely only evolved at the base of the Elegans group. We find that a transgene from C. angaria bearing a single E-box is sufficient for normal expression in C. elegans. Even a short 58 bp cis-regulatory fragment from C. angaria with this single E-box is able to replace the three transcription factor binding sites at the endogenous C. elegans lin-3 locus, resulting in the wild-type expression level. Thus, regulatory evolution occurring in cis within a 58 bp lin-3 fragment, results in a strict requirement for the NHR binding site and a second E-box in C. elegans. This single-cell, single-molecule, quantitative and functional evo-devo study demonstrates that conserved expression levels can hide extensive change in cis-regulatory site requirements and highlights the evolution of new cis-regulatory elements required for cell-specific gene expression. Diversification of mechanisms regulating gene expression of key developmental factors is a major force in the evolution of development. However, in the past, comparisons of gene expression across different species have often been qualitative (i.e. ‘expression is on versus off’ in a certain cell) without precise quantification. New experimental methods now allow us to quantitatively compare the expression of gene homologs across species, with single cell resolution. Moreover, the development of genome editing tools enables the dissection of regulatory DNA sequences that drive gene expression. We use here a well-established “textbook” example of animal organogenesis in the microscopic nematode, Caenorhabditis elegans, focusing on the expression of lin-3, coding for the main inducer of the vulva, in a single cell called the anchor cell. We find that the lin-3 expression level is remarkably conserved, with 20–25 messenger RNAs per anchor cell, in species that are molecularly as distant as fish and mammals. This conservation occurs despite substantial changes and compensation in the regulatory elements required for cell-specific gene expression.
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46
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47
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Sayal R, Dresch JM, Pushel I, Taylor BR, Arnosti DN. Quantitative perturbation-based analysis of gene expression predicts enhancer activity in early Drosophila embryo. eLife 2016; 5. [PMID: 27152947 PMCID: PMC4859806 DOI: 10.7554/elife.08445] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 04/04/2016] [Indexed: 01/02/2023] Open
Abstract
Enhancers constitute one of the major components of regulatory machinery of metazoans. Although several genome-wide studies have focused on finding and locating enhancers in the genomes, the fundamental principles governing their internal architecture and cis-regulatory grammar remain elusive. Here, we describe an extensive, quantitative perturbation analysis targeting the dorsal-ventral patterning gene regulatory network (GRN) controlled by Drosophila NF-κB homolog Dorsal. To understand transcription factor interactions on enhancers, we employed an ensemble of mathematical models, testing effects of cooperativity, repression, and factor potency. Models trained on the dataset correctly predict activity of evolutionarily divergent regulatory regions, providing insights into spatial relationships between repressor and activator binding sites. Importantly, the collective predictions of sets of models were effective at novel enhancer identification and characterization. Our study demonstrates how experimental dataset and modeling can be effectively combined to provide quantitative insights into cis-regulatory information on a genome-wide scale. DOI:http://dx.doi.org/10.7554/eLife.08445.001 DNA contains regions known as genes, which may be “transcribed” to produce the RNA molecules that act as templates for building proteins and regulate cell activity. Proteins called transcription factors can bind to specific sequences of DNA to influence whether nearby genes are transcribed. For example, so-called enhancer regions of DNA contain several binding sites for transcription factors, and this binding activates gene transcription. Little is known about how the transcription factor binding sites are organized in enhancer regions, which makes it difficult to use DNA sequence information alone to predict the regulation of genes. A transcription factor called Dorsal controls the activity of a network of genes that plays a crucial role in the development of fruit fly embryos. Dorsal binds to the enhancer region of a gene called rhomboid, which has been well studied and is known to be a fairly typical example of an enhancer region. To understand the regulatory information encoded in the DNA sequences of enhancers, Sayal, Dresch et al. have now used a technique called perturbation analysis to investigate the interactions that are likely to occur between Dorsal and other transcription factors as they bind to the rhomboid enhancer. This technique involves systematically mutating the enhancer to remove different combinations of transcription factor binding sites and quantitatively investigating the effect this has on gene activity. A large set of mathematical models were then trained using this data and shown to correctly predict the activity of a range of other gene regulatory regions. The collective predictions of the models identified new enhancer regions and revealed details about how different types of transcription factor binding sites are arranged within enhancers. As we enter an era where the DNA sequences of entire human populations are increasingly accessible, we would like to know the functional significance of changes in gene regulatory regions. Sayal, Dresch et al. show that the regulatory properties of specific control proteins are accessible by employing quantitative experiments and mathematical models. Similar studies will be required to learn how mutations found across the genome may alter gene expression, leading to better diagnosis and treatment of disease. DOI:http://dx.doi.org/10.7554/eLife.08445.002
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Affiliation(s)
- Rupinder Sayal
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, United States.,Department of Biochemistry, DAV University, Jalandhar, India
| | - Jacqueline M Dresch
- Department of Mathematics, Michigan State University, East Lansing, United States.,Department of Mathematics and Computer Science, Clark University, Worcester, United States
| | - Irina Pushel
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, United States.,Stowers Institute for Medical Research, Kansas City, United States
| | - Benjamin R Taylor
- Department of Computer Science and Engineering, Michigan State University, East Lansing, United States.,School of Computer Science, Georgia Institute of Technology, Atlanta, United States
| | - David N Arnosti
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, United States
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48
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Lorberbaum DS, Ramos AI, Peterson KA, Carpenter BS, Parker DS, De S, Hillers LE, Blake VM, Nishi Y, McFarlane MR, Chiang AC, Kassis JA, Allen BL, McMahon AP, Barolo S. An ancient yet flexible cis-regulatory architecture allows localized Hedgehog tuning by patched/Ptch1. eLife 2016; 5. [PMID: 27146892 PMCID: PMC4887206 DOI: 10.7554/elife.13550] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 05/03/2016] [Indexed: 12/24/2022] Open
Abstract
The Hedgehog signaling pathway is part of the ancient developmental-evolutionary animal toolkit. Frequently co-opted to pattern new structures, the pathway is conserved among eumetazoans yet flexible and pleiotropic in its effects. The Hedgehog receptor, Patched, is transcriptionally activated by Hedgehog, providing essential negative feedback in all tissues. Our locus-wide dissections of the cis-regulatory landscapes of fly patched and mouse Ptch1 reveal abundant, diverse enhancers with stage- and tissue-specific expression patterns. The seemingly simple, constitutive Hedgehog response of patched/Ptch1 is driven by a complex regulatory architecture, with batteries of context-specific enhancers engaged in promoter-specific interactions to tune signaling individually in each tissue, without disturbing patterning elsewhere. This structure—one of the oldest cis-regulatory features discovered in animal genomes—explains how patched/Ptch1 can drive dramatic adaptations in animal morphology while maintaining its essential core function. It may also suggest a general model for the evolutionary flexibility of conserved regulators and pathways. DOI:http://dx.doi.org/10.7554/eLife.13550.001
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Affiliation(s)
- David S Lorberbaum
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, United States.,Program in Cellular and Molecular Biology, University Of Michigan Medical School, Ann Arbor, United States
| | - Andrea I Ramos
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, United States.,Program in Cellular and Molecular Biology, University Of Michigan Medical School, Ann Arbor, United States
| | - Kevin A Peterson
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, United States.,The Jackson Laboratory, Bar Harbor, United States
| | - Brandon S Carpenter
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, United States
| | - David S Parker
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, United States
| | - Sandip De
- Program in Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States
| | - Lauren E Hillers
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, United States
| | - Victoria M Blake
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, United States.,Program in Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States
| | - Yuichi Nishi
- Department of Stem Cell Biology and Regenerative Medicine, Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research, University of Southern California Keck School of Medicine, Los Angeles, United States
| | - Matthew R McFarlane
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, United States
| | - Ason Cy Chiang
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, United States
| | - Judith A Kassis
- Program in Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States
| | - Benjamin L Allen
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, United States
| | - Andrew P McMahon
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, United States.,Department of Stem Cell Biology and Regenerative Medicine, Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research, University of Southern California Keck School of Medicine, Los Angeles, United States
| | - Scott Barolo
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, United States
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Blick AJ, Mayer-Hirshfeld I, Malibiran BR, Cooper MA, Martino PA, Johnson JE, Bateman JR. The Capacity to Act in Trans Varies Among Drosophila Enhancers. Genetics 2016; 203:203-18. [PMID: 26984057 PMCID: PMC4858774 DOI: 10.1534/genetics.115.185645] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Accepted: 03/07/2016] [Indexed: 01/10/2023] Open
Abstract
The interphase nucleus is organized such that genomic segments interact in cis, on the same chromosome, and in trans, between different chromosomes. In Drosophila and other Dipterans, extensive interactions are observed between homologous chromosomes, which can permit enhancers and promoters to communicate in trans Enhancer action in trans has been observed for a handful of genes in Drosophila, but it is as yet unclear whether this is a general property of all enhancers or specific to a few. Here, we test a collection of well-characterized enhancers for the capacity to act in trans Specifically, we tested 18 enhancers that are active in either the eye or wing disc of third instar Drosophila larvae and, using two different assays, found evidence that each enhancer can act in trans However, the degree to which trans-action was supported varied greatly between enhancers. Quantitative analysis of enhancer activity supports a model wherein an enhancer's strength of transcriptional activation is a major determinant of its ability to act in trans, but that additional factors may also contribute to an enhancer's trans-activity. In sum, our data suggest that a capacity to activate a promoter on a paired chromosome is common among Drosophila enhancers.
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Affiliation(s)
- Amanda J Blick
- Biology Department, Bowdoin College, Brunswick, Maine 04011
| | | | | | | | | | | | - Jack R Bateman
- Biology Department, Bowdoin College, Brunswick, Maine 04011
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Fiore C, Cohen BA. Interactions between pluripotency factors specify cis-regulation in embryonic stem cells. Genome Res 2016; 26:778-86. [PMID: 27197208 PMCID: PMC4889965 DOI: 10.1101/gr.200733.115] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Accepted: 04/13/2016] [Indexed: 01/06/2023]
Abstract
We investigated how interactions between pluripotency transcription factors (TFs) affect cis-regulation. We created hundreds of synthetic cis-regulatory elements (CREs) comprised of combinations of binding sites for pluripotency TFs and measured their expression in mouse embryonic stem (ES) cells. A thermodynamic model that incorporates interactions between TFs explains a large portion (72%) of the variance in expression of these CREs. These interactions include three favorable heterotypic interactions between TFs. The model also predicts an unfavorable homotypic interaction between TFs, helping to explain the observation that homotypic chains of binding sites express at low levels. We further investigated the expression driven by CREs comprised of homotypic chains of KLF4 binding sites. Our results suggest that KLF homologs make unique contributions to regulation by these CREs. We conclude that a specific set of interactions between pluripotency TFs plays a large role in setting the levels of expression driven by CREs in ES cells.
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Affiliation(s)
- Chris Fiore
- Center for Genome Sciences and Systems Biology, Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63110, USA
| | - Barak A Cohen
- Center for Genome Sciences and Systems Biology, Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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