1
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Prud'homme B. The power of proximity: mechanisms and biological roles of transvection. Curr Opin Genet Dev 2024; 89:102269. [PMID: 39368316 DOI: 10.1016/j.gde.2024.102269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2024] [Revised: 09/10/2024] [Accepted: 09/16/2024] [Indexed: 10/07/2024]
Abstract
The phenomenon of transvection, defined as a proximity-dependent interallelic interaction, has been observed in the context of complementation between mutant alleles for numerous Drosophila genes. Cases of transvection-like phenomena have also been observed in other species, including mammals. However, the potential contribution of transvection to wild-type gene regulation and the underlying mechanisms remain uncertain. Here, I review recent evidence demonstrating the relevance of transvection in physiological contexts. These findings suggest that transvection represents an additional layer of gene regulation that allows cells to fine-tune gene expression based on the proximity of homologous alleles. In addition, recent studies have measured the physical distance between interacting alleles, revealing unexpectedly large and variable distances. I will discuss how these distances are compatible with the 'hub' model of transcriptional regulation.
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Affiliation(s)
- Benjamin Prud'homme
- Aix-Marseille Université, CNRS, IBDM, Institut de Biologie du Développement de Marseille, Campus de Luminy Case 907, Cedex 9, 13288 Marseille, France.
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2
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Lavaud M, Tesfaye R, Lassous L, Brounais B, Baud'huin M, Verrecchia F, Lamoureux F, Georges S, Ory B. Super-enhancers: drivers of cells' identities and cells' debacles. Epigenomics 2024; 16:681-700. [PMID: 38587919 PMCID: PMC11160454 DOI: 10.2217/epi-2023-0409] [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: 11/21/2023] [Accepted: 03/18/2024] [Indexed: 04/10/2024] Open
Abstract
Precise spatiotemporal regulations of gene expression are essential for determining cells' fates and functions. Enhancers are cis-acting DNA elements that act as periodic transcriptional thrusters and their activities are cell type specific. Clusters of enhancers, called super-enhancers, are more densely occupied by transcriptional activators than enhancers, driving stronger expression of their target genes, which have prominent roles in establishing and maintaining cellular identities. Here we review the current knowledge on the composition and structure of super-enhancers to understand how they robustly stimulate the expression of cellular identity genes. We also review their involvement in the development of various cell types and both noncancerous and cancerous disorders, implying the therapeutic interest of targeting them to fight against various diseases.
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Affiliation(s)
- Mélanie Lavaud
- CRCI2NA, INSERM UMR 1307, CNRS UMR 6075, Nantes University & Angers University, Medical School, Nantes, 44035, France
| | - Robel Tesfaye
- CRCI2NA, INSERM UMR 1307, CNRS UMR 6075, Nantes University & Angers University, Medical School, Nantes, 44035, France
- Cancéropôle Grand-Ouest, Réseau Épigénétique, Medical School, Nantes, 44035, France
- EpiSAVMEN, Epigenetic consortium Pays de la Loire, France
| | - Léa Lassous
- CRCI2NA, INSERM UMR 1307, CNRS UMR 6075, Nantes University & Angers University, Medical School, Nantes, 44035, France
| | - Bénédicte Brounais
- CRCI2NA, INSERM UMR 1307, CNRS UMR 6075, Nantes University & Angers University, Medical School, Nantes, 44035, France
| | - Marc Baud'huin
- CRCI2NA, INSERM UMR 1307, CNRS UMR 6075, Nantes University & Angers University, Medical School, Nantes, 44035, France
| | - Franck Verrecchia
- CRCI2NA, INSERM UMR 1307, CNRS UMR 6075, Nantes University & Angers University, Medical School, Nantes, 44035, France
| | - François Lamoureux
- CRCI2NA, INSERM UMR 1307, CNRS UMR 6075, Nantes University & Angers University, Medical School, Nantes, 44035, France
| | - Steven Georges
- CRCI2NA, INSERM UMR 1307, CNRS UMR 6075, Nantes University & Angers University, Medical School, Nantes, 44035, France
| | - Benjamin Ory
- CRCI2NA, INSERM UMR 1307, CNRS UMR 6075, Nantes University & Angers University, Medical School, Nantes, 44035, France
- Cancéropôle Grand-Ouest, Réseau Épigénétique, Medical School, Nantes, 44035, France
- EpiSAVMEN, Epigenetic consortium Pays de la Loire, France
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3
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Blum JA, Wells M, Huxley-Reicher Z, Johnson JE, Bateman JR. Transvection between nonallelic genomic positions in Drosophila. G3 (BETHESDA, MD.) 2024; 14:jkad255. [PMID: 37949840 PMCID: PMC10849331 DOI: 10.1093/g3journal/jkad255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 10/24/2023] [Accepted: 11/03/2023] [Indexed: 11/12/2023]
Abstract
In Drosophila, pairing of maternal and paternal homologous chromosomes can permit trans-interactions between enhancers on one homolog and promoters on another, an example of transvection. Although trans-interactions have been observed at many loci in the Drosophila genome and in other organisms, the parameters that govern enhancer action in trans remain poorly understood. Using a transgenic reporter system, we asked whether enhancers and promoters at nonallelic, but nearby, genomic positions can communication in trans. Using one transgenic insertion carrying the synthetic enhancer GMR and another nearby insertion carrying the hsp70 promoter driving a fluorescent reporter, we show that transgenes separated by 2.6 kb of linear distance can support enhancer action in trans at the 53F8 locus. Furthermore, transvection between the nonallelic insertions can be augmented by a small deletion flanking one insert, likely via changes to the paired configuration of the homologs. Subsequent analyses of other insertions in 53F8 that carry different transgenic sequences demonstrate that the capacity to support transvection between nonallelic sites varies greatly, suggesting that factors beyond the linear distance between insertion sites play an important role. Finally, analysis of transvection between nearby nonallelic sites at other genomic locations shows evidence of position effects, where one locus supported GMR action in trans over a linear distance of over 10 kb, whereas another locus showed no evidence of transvection over a span <200 bp. Overall, our data demonstrate that transvection between nonallelic sites represents a complex interplay between genomic context, interallelic distance, and promoter identity.
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Affiliation(s)
- Jacob A Blum
- Biology Department, 2 Polar Loop, Bowdoin College, Brunswick, ME 04011, USA
| | - Michelle Wells
- Biology Department, 2 Polar Loop, Bowdoin College, Brunswick, ME 04011, USA
| | | | - Justine E Johnson
- Biology Department, 2 Polar Loop, Bowdoin College, Brunswick, ME 04011, USA
| | - Jack R Bateman
- Biology Department, 2 Polar Loop, Bowdoin College, Brunswick, ME 04011, USA
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4
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Hehmeyer J, Spitz F, Marlow H. Shifting landscapes: the role of 3D genomic organizations in gene regulatory strategies. Curr Opin Genet Dev 2023; 81:102064. [PMID: 37390583 PMCID: PMC10547022 DOI: 10.1016/j.gde.2023.102064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2023] [Revised: 05/23/2023] [Accepted: 05/24/2023] [Indexed: 07/02/2023]
Abstract
3D genome folding enables the physical storage of chromosomes into the compact volume of a cell's nucleus, allows for the accurate segregation of chromatin to daughter cells, and has been shown to be tightly coupled to the way in which genetic information is converted into transcriptional programs [1-3]. Importantly, this link between chromatin architecture and gene regulation is a selectable feature in which modifications to chromatin organization accompany, or perhaps even drive the establishment of new regulatory strategies with enduring impacts on animal body plan complexity. Here, we discuss the nature of different 3D genome folding systems found across the tree of life, with particular emphasis on metazoans, and the relative influence of these systems on gene regulation. We suggest how the properties of these folding systems have influenced regulatory strategies employed by different lineages and may have catalyzed the partitioning and specialization of genetic programs that enabled multicellularity and organ-grade body plan complexity.
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Affiliation(s)
- Jenks Hehmeyer
- Department of Organismal Biology and Anatomy, The University of Chicago, USA
| | - François Spitz
- Department of Human Genetics, The University of Chicago, USA
| | - Heather Marlow
- Department of Organismal Biology and Anatomy, The University of Chicago, USA.
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5
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Urban EA, Chernoff C, Layng KV, Han J, Anderson C, Konzman D, Johnston RJ. Activating and repressing gene expression between chromosomes during stochastic fate specification. Cell Rep 2023; 42:111910. [PMID: 36640351 PMCID: PMC9976292 DOI: 10.1016/j.celrep.2022.111910] [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: 07/19/2022] [Revised: 10/28/2022] [Accepted: 12/09/2022] [Indexed: 12/31/2022] Open
Abstract
DNA elements act across long genomic distances to regulate gene expression. During transvection in Drosophila, DNA elements on one allele of a gene act between chromosomes to regulate expression of the other allele. Little is known about the biological roles and developmental regulation of transvection. Here, we study the stochastic expression of spineless (ss) in photoreceptors in the fly eye to understand transvection. We determine a biological role for transvection in regulating expression of naturally occurring ss alleles. We identify DNA elements required for activating and repressing transvection. Different enhancers participate in transvection at different times during development to promote gene expression and specify cell fates. Bringing a silencer element on a heterologous chromosome into proximity with the ss locus "reconstitutes" the gene, leading to repression. Our studies show that transvection regulates gene expression via distinct DNA elements at specific timepoints in development, with implications for genome organization and architecture.
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Affiliation(s)
- Elizabeth A. Urban
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA,These authors contributed equally
| | - Chaim Chernoff
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA,Present address: Harvard Stem Cell Institute, Harvard University, 7 Divinity Avenue, Cambridge, MA 02138, USA,These authors contributed equally
| | - Kayla Viets Layng
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
| | - Jeong Han
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
| | - Caitlin Anderson
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
| | - Daniel Konzman
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
| | - Robert J. Johnston
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA,Lead contact,Correspondence:
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6
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Fleck K, Raj R, Erceg J. The 3D genome landscape: Diverse chromosomal interactions and their functional implications. Front Cell Dev Biol 2022; 10:968145. [PMID: 36036013 PMCID: PMC9402908 DOI: 10.3389/fcell.2022.968145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Accepted: 07/19/2022] [Indexed: 11/13/2022] Open
Abstract
Genome organization includes contacts both within a single chromosome and between distinct chromosomes. Thus, regulatory organization in the nucleus may include interplay of these two types of chromosomal interactions with genome activity. Emerging advances in omics and single-cell imaging technologies have allowed new insights into chromosomal contacts, including those of homologs and sister chromatids, and their significance to genome function. In this review, we highlight recent studies in this field and discuss their impact on understanding the principles of chromosome organization and associated functional implications in diverse cellular processes. Specifically, we describe the contributions of intra-chromosomal, inter-homolog, and inter-sister chromatid contacts to genome organization and gene expression.
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Affiliation(s)
- Katherine Fleck
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, United States
| | - Romir Raj
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, United States
| | - Jelena Erceg
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, United States
- Institute for Systems Genomics, University of Connecticut, Storrs, CT, United States
- Department of Genetics and Genome Sciences, University of Connecticut Health Center, Farmington, CT, United States
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7
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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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8
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Child MB, Bateman JR, Jahangiri A, Reimer A, Lammers NC, Sabouni N, Villamarin D, McKenzie-Smith GC, Johnson JE, Jost D, Garcia HG. Live imaging and biophysical modeling support a button-based mechanism of somatic homolog pairing in Drosophila. eLife 2021; 10:64412. [PMID: 34100718 PMCID: PMC8294847 DOI: 10.7554/elife.64412] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 06/07/2021] [Indexed: 12/22/2022] Open
Abstract
Three-dimensional eukaryotic genome organization provides the structural basis for gene regulation. In Drosophila melanogaster, genome folding is characterized by somatic homolog pairing, where homologous chromosomes are intimately paired from end to end; however, how homologs identify one another and pair has remained mysterious. Recently, this process has been proposed to be driven by specifically interacting 'buttons' encoded along chromosomes. Here, we turned this hypothesis into a quantitative biophysical model to demonstrate that a button-based mechanism can lead to chromosome-wide pairing. We tested our model using live-imaging measurements of chromosomal loci tagged with the MS2 and PP7 nascent RNA labeling systems. We show solid agreement between model predictions and experiments in the pairing dynamics of individual homologous loci. Our results strongly support a button-based mechanism of somatic homolog pairing in Drosophila and provide a theoretical framework for revealing the molecular identity and regulation of buttons.
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Affiliation(s)
- Myron Barber Child
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States.,Department of Physics, University of California, Berkeley, Berkeley, United States
| | - Jack R Bateman
- Biology Department, Bowdoin College, Brunswick, United States
| | - Amir Jahangiri
- Univ Grenoble Alpes CNRS, Grenoble INP, TIMC-IMAG, Grenoble, France
| | - Armando Reimer
- Biophysics Graduate Group, University of California, Berkeley, Berkeley, United States
| | - Nicholas C Lammers
- Biophysics Graduate Group, University of California, Berkeley, Berkeley, United States
| | - Nica Sabouni
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | | | | | | | - Daniel Jost
- Univ Grenoble Alpes CNRS, Grenoble INP, TIMC-IMAG, Grenoble, France.,Université de Lyon, ENS de Lyon, Univ Claude Bernard, CNRS, Laboratory of Biology and Modeling of the Cell, Lyon, France
| | - Hernan G Garcia
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States.,Department of Physics, University of California, Berkeley, Berkeley, United States.,Biophysics Graduate Group, University of California, Berkeley, Berkeley, United States.,Institute for Quantitative Biosciences-QB3, University of California, Berkeley, Berkeley, United States
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9
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Cis-regulatory differences in isoform expression associate with life history strategy variation in Atlantic salmon. PLoS Genet 2020; 16:e1009055. [PMID: 32997662 PMCID: PMC7549781 DOI: 10.1371/journal.pgen.1009055] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 10/12/2020] [Accepted: 08/17/2020] [Indexed: 02/07/2023] Open
Abstract
A major goal in biology is to understand how evolution shapes variation in individual life histories. Genome-wide association studies have been successful in uncovering genome regions linked with traits underlying life history variation in a range of species. However, lack of functional studies of the discovered genotype-phenotype associations severely restrains our understanding how alternative life history traits evolved and are mediated at the molecular level. Here, we report a cis-regulatory mechanism whereby expression of alternative isoforms of the transcription co-factor vestigial-like 3 (vgll3) associate with variation in a key life history trait, age at maturity, in Atlantic salmon (Salmo salar). Using a common-garden experiment, we first show that vgll3 genotype associates with puberty timing in one-year-old salmon males. By way of temporal sampling of vgll3 expression in ten tissues across the first year of salmon development, we identify a pubertal transition in vgll3 expression where maturation coincided with a 66% reduction in testicular vgll3 expression. The late maturation allele was not only associated with a tendency to delay puberty, but also with expression of a rare transcript isoform of vgll3 pre-puberty. By comparing absolute vgll3 mRNA copies in heterozygotes we show that the expression difference between the early and late maturity alleles is largely cis-regulatory. We propose a model whereby expression of a rare isoform from the late allele shifts the liability of its carriers towards delaying puberty. These results exemplify the potential importance of regulatory differences as a mechanism for the evolution of life history traits. Alternative life history strategies are an important source of diversity within populations and promote the maintenance of adaptive capacity and population resilience. However, in many cases the molecular basis of different life history strategies remains elusive. Age at maturity is a key adaptive life history trait in Atlantic salmon and has a relatively simple genetic basis. Using salmon age at maturity as a model, we report a mechanism whereby different transcript isoforms of the key age at maturity gene, vestigial-like 3 (vgll3), associate with variation in the timing of male puberty. Our results show how gene regulatory differences in conjunction with variation in gene transcript structure can encode for complex alternative life histories.
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10
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Giri R, Papadopoulos DK, Posadas DM, Potluri HK, Tomancak P, Mani M, Carthew RW. Ordered patterning of the sensory system is susceptible to stochastic features of gene expression. eLife 2020; 9:e53638. [PMID: 32101167 PMCID: PMC7064346 DOI: 10.7554/elife.53638] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 02/25/2020] [Indexed: 01/23/2023] Open
Abstract
Sensory neuron numbers and positions are precisely organized to accurately map environmental signals in the brain. This precision emerges from biochemical processes within and between cells that are inherently stochastic. We investigated impact of stochastic gene expression on pattern formation, focusing on senseless (sens), a key determinant of sensory fate in Drosophila. Perturbing microRNA regulation or genomic location of sens produced distinct noise signatures. Noise was greatly enhanced when both sens alleles were present in homologous loci such that each allele was regulated in trans by the other allele. This led to disordered patterning. In contrast, loss of microRNA repression of sens increased protein abundance but not sensory pattern disorder. This suggests that gene expression stochasticity is a critical feature that must be constrained during development to allow rapid yet accurate cell fate resolution.
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Affiliation(s)
- Ritika Giri
- Department of Molecular Biosciences, Northwestern UniversityEvanstonUnited States
- NSF-Simons Center for Quantitative Biology, Northwestern UniversityEvanstonUnited States
| | | | - Diana M Posadas
- Department of Molecular Biosciences, Northwestern UniversityEvanstonUnited States
| | - Hemanth K Potluri
- Department of Molecular Biosciences, Northwestern UniversityEvanstonUnited States
| | - Pavel Tomancak
- Max Planck Institute of Cell Biology and GeneticsDresdenGermany
| | - Madhav Mani
- Department of Molecular Biosciences, Northwestern UniversityEvanstonUnited States
- NSF-Simons Center for Quantitative Biology, Northwestern UniversityEvanstonUnited States
- Department of Engineering Sciences and Applied Mathematics, Northwestern UniversityEvanstonUnited States
| | - Richard W Carthew
- Department of Molecular Biosciences, Northwestern UniversityEvanstonUnited States
- NSF-Simons Center for Quantitative Biology, Northwestern UniversityEvanstonUnited States
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11
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Chang HC, Huang HC, Juan HF, Hsu CL. Investigating the role of super-enhancer RNAs underlying embryonic stem cell differentiation. BMC Genomics 2019; 20:896. [PMID: 31888456 PMCID: PMC6936076 DOI: 10.1186/s12864-019-6293-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 11/15/2019] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Super-enhancer RNAs (seRNAs) are a kind of noncoding RNA transcribed from super-enhancer regions. The regulation mechanism and functional role of seRNAs are still unclear. Although super-enhancers play a critical role in the core transcriptional regulatory circuity of embryonic stem cell (ESC) differentiation, whether seRNAs have similar properties should be further investigated. RESULTS We analyzed cap analysis gene expression sequencing (CAGE-seq) datasets collected during the differentiation of embryonic stem cells (ESCs) to cardiomyocytes to identify the seRNAs. A non-negative matrix factorization algorithm was applied to decompose the seRNA profiles and reveal two hidden stages during the ESC differentiation. We further identified 95 and 78 seRNAs associated with early- and late-stage ESC differentiation, respectively. We found that the binding sites of master regulators of ESC differentiation, including NANOG, FOXA2, and MYC, were significantly observed in the loci of the stage-specific seRNAs. Based on the investigation of genes coexpressed with seRNA, these stage-specific seRNAs might be involved in cardiac-related functions such as myofibril assembly and heart development and act in trans to regulate the co-expressed genes. CONCLUSIONS In this study, we used a computational approach to demonstrate the possible role of seRNAs during ESC differentiation.
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Affiliation(s)
- Hao-Chun Chang
- Graduate Institute of Biomedical Electronics and Bioinformatics, National Taiwan University, Taipei, Taiwan
| | - Hsuan-Cheng Huang
- Institute of Biomedical Informatics, National Yang-Ming University, Taipei, Taiwan
| | - Hsueh-Fen Juan
- Graduate Institute of Biomedical Electronics and Bioinformatics, National Taiwan University, Taipei, Taiwan
- Department of Life Science, National Taiwan University, Taipei, Taiwan
| | - Chia-Lang Hsu
- Department of Medical Research, National Taiwan University Hospital, Taipei, Taiwan
- Graduate Institute of Oncology, National Taiwan University College of Medicine, Taipei, Taiwan
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12
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King TD, Johnson JE, Bateman JR. Position Effects Influence Transvection in Drosophila melanogaster. Genetics 2019; 213:1289-1299. [PMID: 31611231 PMCID: PMC6893391 DOI: 10.1534/genetics.119.302583] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 10/03/2019] [Indexed: 01/14/2023] Open
Abstract
Transvection is an epigenetic phenomenon wherein regulatory elements communicate between different chromosomes in trans, and is thereby dependent upon the three-dimensional organization of the genome. Transvection is best understood in Drosophila, where homologous chromosomes are closely paired in most somatic nuclei, although similar phenomena have been observed in other species. Previous data have supported that the Drosophila genome is generally permissive to enhancer action in trans, a form of transvection where an enhancer on one homolog activates gene expression from a promoter on a paired homolog. However, the capacity of different genomic positions to influence the quantitative output of transvection has yet to be addressed. To investigate this question, we employed a transgenic system that assesses and compares enhancer action in cis and in trans at defined chromosomal locations. Using the strong synthetic eye-specific enhancer GMR, we show that loci supporting strong cis-expression tend to support robust enhancer action in trans, whereas locations with weaker cis-expression show reduced transvection in a fluorescent reporter assay. Our subsequent analysis is consistent with a model wherein the chromatin state of the transgenic insertion site is a primary determinant of the degree to which enhancer action in trans will be supported, whereas other factors such as locus-specific variation in somatic homolog pairing are of less importance in influencing position effects on transvection.
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Affiliation(s)
- Thomas D King
- Biology Department, Bowdoin College, Brunswick, Maine 04011
| | | | - Jack R Bateman
- Biology Department, Bowdoin College, Brunswick, Maine 04011
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13
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Viets K, Sauria MEG, Chernoff C, Rodriguez Viales R, Echterling M, Anderson C, Tran S, Dove A, Goyal R, Voortman L, Gordus A, Furlong EEM, Taylor J, Johnston RJ. Characterization of Button Loci that Promote Homologous Chromosome Pairing and Cell-Type-Specific Interchromosomal Gene Regulation. Dev Cell 2019; 51:341-356.e7. [PMID: 31607649 DOI: 10.1016/j.devcel.2019.09.007] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 06/07/2019] [Accepted: 09/09/2019] [Indexed: 01/05/2023]
Abstract
Homologous chromosomes colocalize to regulate gene expression in processes including genomic imprinting, X-inactivation, and transvection. In Drosophila, homologous chromosomes pair throughout development, promoting transvection. The "button" model of pairing proposes that specific regions along chromosomes pair with high affinity. Here, we identify buttons interspersed across the fly genome that pair with their homologous sequences, even when relocated to multiple positions in the genome. A majority of transgenes that span a full topologically associating domain (TAD) function as buttons, but not all buttons contain TADs. Additionally, buttons are enriched for insulator protein clusters. Fragments of buttons do not pair, suggesting that combinations of elements within a button are required for pairing. Pairing is necessary but not sufficient for transvection. Additionally, pairing and transvection are stronger in some cell types than in others, suggesting that pairing strength regulates transvection efficiency between cell types. Thus, buttons pair homologous chromosomes to facilitate cell-type-specific interchromosomal gene regulation.
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Affiliation(s)
- Kayla Viets
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Michael E G Sauria
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Chaim Chernoff
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | | | - Max Echterling
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Caitlin Anderson
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Sang Tran
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Abigail Dove
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Raghav Goyal
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Lukas Voortman
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Andrew Gordus
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Eileen E M Furlong
- European Molecular Biology Laboratory, Department of Genome Biology, Heidelberg 69117, Germany
| | - James Taylor
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Robert J Johnston
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA.
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14
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AlHaj Abed J, Erceg J, Goloborodko A, Nguyen SC, McCole RB, Saylor W, Fudenberg G, Lajoie BR, Dekker J, Mirny LA, Wu CT. Highly structured homolog pairing reflects functional organization of the Drosophila genome. Nat Commun 2019; 10:4485. [PMID: 31582763 PMCID: PMC6776532 DOI: 10.1038/s41467-019-12208-3] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Accepted: 08/27/2019] [Indexed: 01/14/2023] Open
Abstract
Trans-homolog interactions have been studied extensively in Drosophila, where homologs are paired in somatic cells and transvection is prevalent. Nevertheless, the detailed structure of pairing and its functional impact have not been thoroughly investigated. Accordingly, we generated a diploid cell line from divergent parents and applied haplotype-resolved Hi-C, showing that homologs pair with varying precision genome-wide, in addition to establishing trans-homolog domains and compartments. We also elucidate the structure of pairing with unprecedented detail, observing significant variation across the genome and revealing at least two forms of pairing: tight pairing, spanning contiguous small domains, and loose pairing, consisting of single larger domains. Strikingly, active genomic regions (A-type compartments, active chromatin, expressed genes) correlated with tight pairing, suggesting that pairing has a functional implication genome-wide. Finally, using RNAi and haplotype-resolved Hi-C, we show that disruption of pairing-promoting factors results in global changes in pairing, including the disruption of some interaction peaks.
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Affiliation(s)
- Jumana AlHaj Abed
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA
| | - Jelena Erceg
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA
| | - Anton Goloborodko
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology (MIT), Cambridge, MA, 02139, USA
| | - Son C Nguyen
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA
- Department of Genetics, Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104-6145, USA
| | - Ruth B McCole
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA
| | - Wren Saylor
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA
| | - Geoffrey Fudenberg
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology (MIT), Cambridge, MA, 02139, USA
- Gladstone Institutes of Data Science and Biotechnology, San Francisco, CA, 94158, USA
| | - Bryan R Lajoie
- Howard Hughes Medical Institute and Program in Systems Biology, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, 01605-0103, USA
- Illumina, San Diego, CA, USA
| | - Job Dekker
- Howard Hughes Medical Institute and Program in Systems Biology, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, 01605-0103, USA
| | - Leonid A Mirny
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology (MIT), Cambridge, MA, 02139, USA.
- Department of Physics, Massachusetts Institute of Technology (MIT), Cambridge, MA, 02139, USA.
| | - C-Ting Wu
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA.
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, 02115, USA.
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15
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Piwko P, Vitsaki I, Livadaras I, Delidakis C. The Role of Insulators in Transgene Transvection in Drosophila. Genetics 2019; 212:489-508. [PMID: 30948430 PMCID: PMC6553826 DOI: 10.1534/genetics.119.302165] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 04/02/2019] [Indexed: 12/19/2022] Open
Abstract
Transvection is the phenomenon where a transcriptional enhancer activates a promoter located on the homologous chromosome. It has been amply documented in Drosophila where homologs are closely paired in most, if not all, somatic nuclei, but it has been known to rarely occur in mammals as well. We have taken advantage of site-directed transgenesis to insert reporter constructs into the same genetic locus in Drosophila and have evaluated their ability to engage in transvection by testing many heterozygous combinations. We find that transvection requires the presence of an insulator element on both homologs. Homotypic trans-interactions between four different insulators can support transvection: the gypsy insulator (GI), Wari, Fab-8 and 1A2; GI and Fab-8 are more effective than Wari or 1A2 We show that, in the presence of insulators, transvection displays the characteristics that have been previously described: it requires homolog pairing, but can happen at any of several loci in the genome; a solitary enhancer confronted with an enhancerless reporter is sufficient to drive transcription; it is weaker than the action of the same enhancer-promoter pair in cis, and it is further suppressed by cis-promoter competition. Though necessary, the presence of homotypic insulators is not sufficient for transvection; their position, number and orientation matters. A single GI adjacent to both enhancer and promoter is the optimal configuration. The identity of enhancers and promoters in the vicinity of a trans-interacting insulator pair is also important, indicative of complex insulator-enhancer-promoter interactions.
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Affiliation(s)
- Pawel Piwko
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology Hellas, Heraklion 70013, Crete, Greece
- Department of Biology, University of Crete, Heraklion 70013, Crete, Greece
| | - Ilektra Vitsaki
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology Hellas, Heraklion 70013, Crete, Greece
- Department of Biology, University of Crete, Heraklion 70013, Crete, Greece
| | - Ioannis Livadaras
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology Hellas, Heraklion 70013, Crete, Greece
| | - Christos Delidakis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology Hellas, Heraklion 70013, Crete, Greece
- Department of Biology, University of Crete, Heraklion 70013, Crete, Greece
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16
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Tian K, Henderson RE, Parker R, Brown A, Johnson JE, Bateman JR. Two modes of transvection at the eyes absent gene of Drosophila demonstrate plasticity in transcriptional regulatory interactions in cis and in trans. PLoS Genet 2019; 15:e1008152. [PMID: 31075100 PMCID: PMC6530868 DOI: 10.1371/journal.pgen.1008152] [Citation(s) in RCA: 11] [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: 02/12/2019] [Revised: 05/22/2019] [Accepted: 04/23/2019] [Indexed: 01/10/2023] Open
Abstract
For many genes, proper gene expression requires coordinated and dynamic interactions between multiple regulatory elements, each of which can either promote or silence transcription. In Drosophila, the complexity of the regulatory landscape is further complicated by the tight physical pairing of homologous chromosomes, which can permit regulatory elements to interact in trans, a phenomenon known as transvection. To better understand how gene expression can be programmed through cis- and trans-regulatory interactions, we analyzed transvection effects for a collection of alleles of the eyes absent (eya) gene. We find that trans-activation of a promoter by the eya eye-specific enhancers is broadly supported in many allelic backgrounds, and that the availability of an enhancer to act in trans can be predicted based on the molecular lesion of an eya allele. Furthermore, by manipulating promoter availability in cis and in trans, we demonstrate that the eye-specific enhancers of eya show plasticity in their promoter preference between two different transcriptional start sites, which depends on promoter competition between the two potential targets. Finally, we show that certain alleles of eya demonstrate pairing-sensitive silencing resulting from trans-interactions between Polycomb Response Elements (PREs), and genetic and genomic data support a general role for PcG proteins in mediating transcriptional silencing at eya. Overall, our data highlight how eya gene regulation relies upon a complex but plastic interplay between multiple enhancers, promoters, and PREs. Gene regulation requires interactions between regions of DNA known as regulatory elements, which, in combination, determine where and when a gene will be active or silenced. Some genes use just a few regulatory elements, whereas others rely on highly complex interactions between many different elements that are poorly understood. While we typically imagine regulatory elements interacting with one another along the length of a single chromosome, in a curious phenomenon called transvection, elements can communicate between two different chromosomes that are held in close proximity. Here, we use the study of transvection to better understand how different regulatory elements contribute to the expression of eyes absent (eya), a gene required for proper eye development in Drosophila. Our data show that a class of elements that initiate eya gene expression, called promoters, will compete with one another for activation by eya’s enhancers, a second class of regulatory element, with the promoter that is closest to the enhancers being the favored target for activation. Furthermore, our study of transvection uncovers an important role for a silencing element, called a PRE, in opposing eya gene expression. Overall, our study sheds new light on how different elements combine to produce patterned expression of eya.
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Affiliation(s)
- Katherine Tian
- Biology Department, Bowdoin College, Brunswick, Maine, United States of America
| | - Rachel E. Henderson
- Biology Department, Bowdoin College, Brunswick, Maine, United States of America
| | - Reyna Parker
- Biology Department, Bowdoin College, Brunswick, Maine, United States of America
| | - Alexia Brown
- Biology Department, Bowdoin College, Brunswick, Maine, United States of America
| | - Justine E. Johnson
- Biology Department, Bowdoin College, Brunswick, Maine, United States of America
| | - Jack R. Bateman
- Biology Department, Bowdoin College, Brunswick, Maine, United States of America
- * E-mail:
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17
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Ho EYK, Cao Q, Gu M, Chan RWL, Wu Q, Gerstein M, Yip KY. Shaping the nebulous enhancer in the era of high-throughput assays and genome editing. Brief Bioinform 2019; 21:836-850. [PMID: 30895290 DOI: 10.1093/bib/bbz030] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 02/15/2019] [Accepted: 02/26/2019] [Indexed: 01/22/2023] Open
Abstract
Since the 1st discovery of transcriptional enhancers in 1981, their textbook definition has remained largely unchanged in the past 37 years. With the emergence of high-throughput assays and genome editing, which are switching the paradigm from bottom-up discovery and testing of individual enhancers to top-down profiling of enhancer activities genome-wide, it has become increasingly evidenced that this classical definition has left substantial gray areas in different aspects. Here we survey a representative set of recent research articles and report the definitions of enhancers they have adopted. The results reveal that a wide spectrum of definitions is used usually without the definition stated explicitly, which could lead to difficulties in data interpretation and downstream analyses. Based on these findings, we discuss the practical implications and suggestions for future studies.
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Affiliation(s)
| | - Qin Cao
- Department of Computer Science and Engineering, The Chinese University of Hong Kong, Hong Kong
| | - Mengting Gu
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA
| | - Ricky Wai-Lun Chan
- Department of Computer Science and Engineering, The Chinese University of Hong Kong, Hong Kong
| | - Qiong Wu
- Department of Computer Science and Engineering, The Chinese University of Hong Kong, Hong Kong.,School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong
| | - Mark Gerstein
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA.,Program in Computational Biology and Bioinformatics.,Department of Computer Science, Yale University, New Haven, Connecticut, USA
| | - Kevin Y Yip
- Department of Biomedical Engineering.,Department of Computer Science and Engineering, The Chinese University of Hong Kong, Hong Kong.,Hong Kong Bioinformatics Centre.,CUHK-BGI Innovation Institute of Trans-omics.,Hong Kong Institute of Diabetes and Obesity, The Chinese University of Hong Kong, Hong Kong
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18
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The Role of Nucleosomes in Epigenetic Gene Regulation. Clin Epigenetics 2019. [DOI: 10.1007/978-981-13-8958-0_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
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19
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Lim B, Heist T, Levine M, Fukaya T. Visualization of Transvection in Living Drosophila Embryos. Mol Cell 2018; 70:287-296.e6. [PMID: 29606591 DOI: 10.1016/j.molcel.2018.02.029] [Citation(s) in RCA: 113] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 02/09/2018] [Accepted: 02/23/2018] [Indexed: 01/01/2023]
Abstract
How remote enhancers interact with appropriate target genes persists as a central mystery in gene regulation. Here, we exploit the properties of transvection to explore enhancer-promoter communication between homologous chromosomes in living Drosophila embryos. We successfully visualized the activation of an MS2-tagged reporter gene by a defined developmental enhancer located in trans on the other homolog. This trans-homolog activation depends on insulator DNAs, which increase the stability-but not the frequency-of homolog pairing. A pair of heterotypic insulators failed to mediate transvection, raising the possibility that insulator specificity underlies the formation of chromosomal loop domains. Moreover, we found that a shared enhancer co-activates separate PP7 and MS2 reporter genes incis and intrans. Transvecting alleles weakly compete with one another, raising the possibility that they share a common pool of the transcription machinery. We propose that transvecting alleles form a trans-homolog "hub," which serves as a scaffold for the accumulation of transcription complexes.
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Affiliation(s)
- Bomyi Lim
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
| | - Tyler Heist
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
| | - Michael Levine
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA; Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA.
| | - Takashi Fukaya
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA.
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20
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Humberg TH, Bruegger P, Afonso B, Zlatic M, Truman JW, Gershow M, Samuel A, Sprecher SG. Dedicated photoreceptor pathways in Drosophila larvae mediate navigation by processing either spatial or temporal cues. Nat Commun 2018; 9:1260. [PMID: 29593252 PMCID: PMC5871836 DOI: 10.1038/s41467-018-03520-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Accepted: 02/21/2018] [Indexed: 11/09/2022] Open
Abstract
To integrate changing environmental cues with high spatial and temporal resolution is critical for animals to orient themselves. Drosophila larvae show an effective motor program to navigate away from light sources. How the larval visual circuit processes light stimuli to control navigational decision remains unknown. The larval visual system is composed of two sensory input channels, Rhodopsin5 (Rh5) and Rhodopsin6 (Rh6) expressing photoreceptors (PRs). We here characterize how spatial and temporal information are used to control navigation. Rh6-PRs are required to perceive temporal changes of light intensity during head casts, while Rh5-PRs are required to control behaviors that allow navigation in response to spatial cues. We characterize how distinct behaviors are modulated and identify parallel acting and converging features of the visual circuit. Functional features of the larval visual circuit highlight the principle of how early in a sensory circuit distinct behaviors may be computed by partly overlapping sensory pathways.
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Affiliation(s)
| | - Pascal Bruegger
- Department of Biology, University of Fribourg, 1700, Fribourg, Switzerland
| | - Bruno Afonso
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, 20147, VA, USA
| | - Marta Zlatic
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, 20147, VA, USA.,Department of Zoology, University of Cambridge, CB2 3EJ, Cambridge, UK
| | - James W Truman
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, 20147, VA, USA
| | - Marc Gershow
- Department of Physics and Center for Neural Science, New York University, New York, 10003, NY, USA
| | - Aravinthan Samuel
- Department of Physics and Center for Brain Science, Harvard University, Cambridge, 02138, MA, USA
| | - Simon G Sprecher
- Department of Biology, University of Fribourg, 1700, Fribourg, Switzerland.
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21
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Abstract
Serine integrases catalyze precise rearrangement of DNA through site-specific recombination of small sequences of DNA called attachment (att) sites. Unlike other site-specific recombinases, the recombination reaction driven by serine integrases is highly directional and can only be reversed in the presence of an accessory protein called a recombination directionality factor (RDF). The ability to control reaction directionality has led to the development of serine integrases as tools for controlled rearrangement and modification of DNA in synthetic biology, gene therapy, and biotechnology. This review discusses recent advances in serine integrase technologies focusing on their applications in genome engineering, DNA assembly, and logic and data storage devices.
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Affiliation(s)
- Christine A. Merrick
- School
of Biological Sciences, University of Edinburgh, Roger Land Building, Alexander Crum
Brown Road, Edinburgh EH9
3FF, U.K
| | - Jia Zhao
- Novo
Nordisk (China) Pharmaceuticals Co., Ltd., Lei Shing Hong Center, Guangshunnan Avenue, Beijing 100102, China
| | - Susan J. Rosser
- School
of Biological Sciences, University of Edinburgh, Roger Land Building, Alexander Crum
Brown Road, Edinburgh EH9
3FF, U.K
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22
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Interallelic Transcriptional Enhancement as an in Vivo Measure of Transvection in Drosophila melanogaster. G3-GENES GENOMES GENETICS 2016; 6:3139-3148. [PMID: 27489208 PMCID: PMC5068936 DOI: 10.1534/g3.116.032300] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Transvection—pairing-dependent interallelic regulation resulting from enhancer action in trans—occurs throughout the Drosophila melanogaster genome, likely as a result of the extensive somatic homolog pairing seen in Dipteran species. Recent studies of transvection in Drosophila have demonstrated important qualitative differences between enhancer action in cisvs.in trans, as well as a modest synergistic effect of cis- and trans-acting enhancers on total tissue transcript levels at a given locus. In the present study, we identify a system in which cis- and trans-acting GAL4-UAS enhancer synergism has an unexpectedly large quantitative influence on gene expression, boosting total tissue transcript levels at least fourfold relative to those seen in the absence of transvection. We exploit this strong quantitative effect by using publicly available UAS-shRNA constructs from the TRiP library to assay candidate genes for transvection activity in vivo. The results of the present study, which demonstrate that in trans activation by simple UAS enhancers can have large quantitative effects on gene expression in Drosophila, have important new implications for experimental design utilizing the GAL4-UAS system.
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23
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A Drosophila LexA Enhancer-Trap Resource for Developmental Biology and Neuroendocrine Research. G3-GENES GENOMES GENETICS 2016; 6:3017-3026. [PMID: 27527793 PMCID: PMC5068927 DOI: 10.1534/g3.116.031229] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Novel binary gene expression tools like the LexA-LexAop system could powerfully enhance studies of metabolism, development, and neurobiology in Drosophila However, specific LexA drivers for neuroendocrine cells and many other developmentally relevant systems remain limited. In a unique high school biology course, we generated a LexA-based enhancer trap collection by transposon mobilization. The initial collection provides a source of novel LexA-based elements that permit targeted gene expression in the corpora cardiaca, cells central for metabolic homeostasis, and other neuroendocrine cell types. The collection further contains specific LexA drivers for stem cells and other enteric cells in the gut, and other developmentally relevant tissue types. We provide detailed analysis of nearly 100 new LexA lines, including molecular mapping of insertions, description of enhancer-driven reporter expression in larval tissues, and adult neuroendocrine cells, comparison with established enhancer trap collections and tissue specific RNAseq. Generation of this open-resource LexA collection facilitates neuroendocrine and developmental biology investigations, and shows how empowering secondary school science can achieve research and educational goals.
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24
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Buffry AD, Mendes CC, McGregor AP. The Functionality and Evolution of Eukaryotic Transcriptional Enhancers. ADVANCES IN GENETICS 2016; 96:143-206. [PMID: 27968730 DOI: 10.1016/bs.adgen.2016.08.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Enhancers regulate precise spatial and temporal patterns of gene expression in eukaryotes and, moreover, evolutionary changes in these modular cis-regulatory elements may represent the predominant genetic basis for phenotypic evolution. Here, we review approaches to identify and functionally analyze enhancers and their transcription factor binding sites, including assay for transposable-accessible chromatin-sequencing (ATAC-Seq) and clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9, respectively. We also explore enhancer functionality, including how transcription factor binding sites combine to regulate transcription, as well as research on shadow and super enhancers, and how enhancers can act over great distances and even in trans. Finally, we discuss recent theoretical and empirical data on how transcription factor binding sites and enhancers evolve. This includes how the function of enhancers is maintained despite the turnover of transcription factor binding sites as well as reviewing studies where mutations in enhancers have been shown to underlie morphological change.
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Affiliation(s)
- A D Buffry
- Oxford Brookes University, Oxford, United Kingdom
| | - C C Mendes
- Oxford Brookes University, Oxford, United Kingdom
| | - A P McGregor
- Oxford Brookes University, Oxford, United Kingdom
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25
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Investigating the Interplay between Sister Chromatid Cohesion and Homolog Pairing in Drosophila Nuclei. PLoS Genet 2016; 12:e1006169. [PMID: 27541002 PMCID: PMC4991795 DOI: 10.1371/journal.pgen.1006169] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 06/14/2016] [Indexed: 11/19/2022] Open
Abstract
Following DNA replication, sister chromatids must stay connected for the remainder of the cell cycle in order to ensure accurate segregation in the subsequent cell division. This important function involves an evolutionarily conserved protein complex known as cohesin; any loss of cohesin causes premature sister chromatid separation in mitosis. Here, we examined the role of cohesin in sister chromatid cohesion prior to mitosis, using fluorescence in situ hybridization (FISH) to assay the alignment of sister chromatids in interphase Drosophila cells. Surprisingly, we found that sister chromatid cohesion can be maintained in G2 with little to no cohesin. This capacity to maintain cohesion is widespread in Drosophila, unlike in other systems where a reduced dependence on cohesin for sister chromatid segregation has been observed only at specific chromosomal regions, such as the rDNA locus in budding yeast. Additionally, we show that condensin II antagonizes the alignment of sister chromatids in interphase, supporting a model wherein cohesin and condensin II oppose each other’s functions in the alignment of sister chromatids. Finally, because the maternal and paternal homologs are paired in the somatic cells of Drosophila, and because condensin II has been shown to antagonize this pairing, we consider the possibility that condensin II-regulated mechanisms for aligning homologous chromosomes may also contribute to sister chromatid cohesion. As cells grow, they replicate their DNA to give rise to two copies of each chromosome, known as sister chromatids, which separate from each other once the cell divides. To ensure that sister chromatids end up in different daughter cells, they are kept together from DNA replication until mitosis via a connection known as cohesion. A protein complex known as cohesin is essential for this process. Our work in Drosophila cells suggests that factors other than cohesin also contribute to sister chromatid cohesion in interphase. Additionally, we observed that the alignment of sister chromatids is regulated by condensin II, a protein complex involved in the compaction of chromosomes prior to division as well as the regulation of inter-chromosomal associations. These findings highlight that, in addition to their important individual functions, cohesin and condensin II proteins may interact to organize chromosomes over the course of the cell cycle. Finally, building on prior observations that condensin II is involved in the regulation of somatic homolog pairing in Drosophila, our work suggests that the mechanisms underlying homolog pairing may also contribute to sister chromatid cohesion.
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26
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Spitz F. Gene regulation at a distance: From remote enhancers to 3D regulatory ensembles. Semin Cell Dev Biol 2016; 57:57-67. [PMID: 27364700 DOI: 10.1016/j.semcdb.2016.06.017] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Accepted: 06/24/2016] [Indexed: 10/21/2022]
Abstract
Large-scale identification of elements associated with gene expression revealed that many of them are located extremely far from gene transcriptional start sites. We review here the growing evidence that show that distal cis-acting elements provide key instructions to genes, as genetic variation affecting them is growingly identified as an importance source of phenotypic diversity and disease. We discuss the different mechanisms that allow these elements to exert their regulatory functions, in a robust and specific manner, despite the large genomic distances separating them from their target genes. We particularly focus on the role of the structural organization of the genome in guiding such regulatory interactions.
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Affiliation(s)
- François Spitz
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany; Genome Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany; Department of Developmental Biology and Stem Cells, Institut Pasteur, Paris, France.
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27
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Transvection in Drosophila: trans-interaction between yellow enhancers and promoter is strongly suppressed by a cis-promoter only in certain genomic regions. Chromosoma 2016; 126:431-441. [DOI: 10.1007/s00412-016-0605-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Revised: 06/02/2016] [Accepted: 06/07/2016] [Indexed: 01/26/2023]
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28
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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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29
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Joyce EF, Erceg J, Wu CT. Pairing and anti-pairing: a balancing act in the diploid genome. Curr Opin Genet Dev 2016; 37:119-128. [PMID: 27065367 DOI: 10.1016/j.gde.2016.03.002] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Revised: 03/02/2016] [Accepted: 03/05/2016] [Indexed: 12/22/2022]
Abstract
The presence of maternal and paternal homologs appears to be much more than just a doubling of genetic material. We know this because genomes have evolved elaborate mechanisms that permit homologous regions to sense and then respond to each other. One way in which homologs communicate is to come into contact and, in fact, Dipteran insects such as Drosophila excel at this task, aligning all pairs of maternal and paternal chromosomes, end-to-end, in essentially all somatic tissues throughout development. Here, we reexamine the widely held tenet that extensive somatic pairing of homologous sequences cannot occur in mammals and suggest, instead, that pairing may be a widespread and significant potential that has gone unnoticed in mammals because they expend considerable effort to prevent it. We then extend this discussion to interchromosomal interactions, in general, and speculate about the potential of nuclear organization and pairing to impact inheritance.
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Affiliation(s)
- Eric F Joyce
- Department of Genetics, Harvard Medical School, Boston, MA 02115, United States.
| | - Jelena Erceg
- Department of Genetics, Harvard Medical School, Boston, MA 02115, United States
| | - C-Ting Wu
- Department of Genetics, Harvard Medical School, Boston, MA 02115, United States.
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30
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Lorent K, Gong W, Koo KA, Waisbourd-Zinman O, Karjoo S, Zhao X, Sealy I, Kettleborough RN, Stemple DL, Windsor PA, Whittaker SJ, Porter JR, Wells RG, Pack M. Identification of a plant isoflavonoid that causes biliary atresia. Sci Transl Med 2016; 7:286ra67. [PMID: 25947162 DOI: 10.1126/scitranslmed.aaa1652] [Citation(s) in RCA: 101] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Biliary atresia (BA) is a rapidly progressive and destructive fibrotic disorder of unknown etiology affecting the extrahepatic biliary tree of neonates. Epidemiological studies suggest that an environmental factor, such as a virus or toxin, is the cause of the disease, although none have been definitively established. Several naturally occurring outbreaks of BA in Australian livestock have been associated with the ingestion of unusual plants by pregnant animals during drought conditions. We used a biliary secretion assay in zebrafish to isolate a previously undescribed isoflavonoid, biliatresone, from Dysphania species implicated in a recent BA outbreak. This compound caused selective destruction of the extrahepatic, but not intrahepatic, biliary system of larval zebrafish. A mutation that enhanced biliatresone toxicity mapped to a region of the zebrafish genome that has conserved synteny with an established human BA susceptibility locus. The toxin also caused loss of cilia in neonatal mouse extrahepatic cholangiocytes in culture and disrupted cell polarity and monolayer integrity in cholangiocyte spheroids. Together, these findings provide direct evidence that BA could be initiated by perinatal exposure to an environmental toxin.
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Affiliation(s)
- Kristin Lorent
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Weilong Gong
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Kyung A Koo
- Department of Biological Sciences, University of the Sciences, Philadelphia, PA 19104, USA
| | - Orith Waisbourd-Zinman
- Division of Pediatric Gastroenterology, Hepatology, and Nutrition, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA. Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel
| | - Sara Karjoo
- Division of Pediatric Gastroenterology, Hepatology, and Nutrition, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Xiao Zhao
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Ian Sealy
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SA, UK
| | - Ross N Kettleborough
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SA, UK
| | - Derek L Stemple
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SA, UK
| | - Peter A Windsor
- Faculty of Veterinary Science, University of Sydney, Camden, New South Wales 2570, Australia
| | - Stephen J Whittaker
- Hume Livestock Health and Pest Authority, Albury, New South Wales 2640, Australia
| | - John R Porter
- Department of Biological Sciences, University of the Sciences, Philadelphia, PA 19104, USA
| | - Rebecca G Wells
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA. Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
| | - Michael Pack
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA. Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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31
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Affiliation(s)
- Huy Q. Nguyen
- Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire 03755;
| | - Giovanni Bosco
- Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire 03755;
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Tools for Targeted Genome Engineering of Established Drosophila Cell Lines. Genetics 2015; 201:1307-18. [PMID: 26450921 PMCID: PMC4676523 DOI: 10.1534/genetics.115.181610] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 10/04/2015] [Indexed: 11/18/2022] Open
Abstract
We describe an adaptation of φC31 integrase-mediated targeted cassette exchange for use in Drosophila cell lines. Single copies of an attP-bounded docking platform carrying a GFP-expression marker, with or without insulator elements flanking the attP sites, were inserted by P-element transformation into the Kc167 and Sg4 cell lines; each of the resulting docking-site lines carries a single mapped copy of one of the docking platforms. Vectors for targeted substitution contain a cloning cassette flanked by attB sites. Targeted substitution occurs by integrase-mediated substitution between the attP sites (integrated) and the attB sites (vector). We describe procedures for isolating cells carrying the substitutions and for eliminating the products of secondary off-target events. We demonstrate the technology by integrating a cassette containing a Cu(2+)-inducible mCherry marker, and we report the expression properties of those lines. When compared with clonal lines made by traditional transformation methods, which lead to the illegitimate insertion of tandem arrays, targeted insertion lines give more uniform expression, lower basal expression, and higher induction ratios. Targeted substitution, though intricate, affords results that should greatly improve comparative expression assays-a major emphasis of cell-based studies.
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Generating customized transgene landing sites and multi-transgene arrays in Drosophila using phiC31 integrase. Genetics 2015; 199:919-34. [PMID: 25680812 PMCID: PMC4391550 DOI: 10.1534/genetics.114.173187] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 02/09/2015] [Indexed: 01/05/2023] Open
Abstract
Transgenesis in numerous eukaryotes has been facilitated by the use of site-specific integrases to stably insert transgenes at predefined genomic positions (landing sites). However, the utility of integrase-mediated transgenesis in any system is constrained by the limited number and variable expression properties of available landing sites. By exploiting the nonstandard recombination activity exhibited by a phiC31 integrase mutant, we developed a rapid and inexpensive method for isolating landing sites that exhibit desired expression properties. Additionally, we devised a simple technique for constructing arrays of transgenes at a single landing site, thereby extending the utility of previously characterized landing sites. Using the fruit fly Drosophila melanogaster, we demonstrate the feasibility of these approaches by isolating new landing sites optimized to express transgenes in the nervous system and by building fluorescent reporter arrays at several landing sites. Because these strategies require the activity of only a single exogenous protein, we anticipate that they will be portable to species such as nonmodel organisms, in which genetic manipulation is more challenging, expediting the development of genetic resources in these systems.
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Transvection-based gene regulation in Drosophila is a complex and plastic trait. G3-GENES GENOMES GENETICS 2014; 4:2175-87. [PMID: 25213691 PMCID: PMC4232543 DOI: 10.1534/g3.114.012484] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Transvection, a chromosome pairing-dependent form of trans-based gene regulation, is potentially widespread in the Drosophila melanogaster genome and varies across cell types and within tissues in D. melanogaster, characteristics of a complex trait. Here, we demonstrate that the trans-interactions at the Malic enzyme (Men) locus are, in fact, transvection as classically defined and are plastic with respect to both genetic background and environment. Using chromosomal inversions, we show that trans-interactions at the Men locus are eliminated by changes in chromosomal architecture that presumably disrupt somatic pairing. We further show that the magnitude of transvection at the Men locus is modified by both genetic background and environment (temperature), demonstrating that transvection is a plastic phenotype. Our results suggest that transvection effects in D. melanogaster are shaped by a dynamic interplay between environment and genetic background. Interestingly, we find that cis-based regulation of the Men gene is more robust to genetic background and environment than trans-based. Finally, we begin to uncover the nonlocal factors that may contribute to variation in transvection overall, implicating Abd-B in the regulation of Men in cis and in trans in an allele-specific and tissue-specific manner, driven by differences in expression of the two genes across genetic backgrounds and environmental conditions.
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Schoborg T, Kuruganti S, Rickels R, Labrador M. The Drosophila gypsy insulator supports transvection in the presence of the vestigial enhancer. PLoS One 2013; 8:e81331. [PMID: 24236213 PMCID: PMC3827471 DOI: 10.1371/journal.pone.0081331] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Accepted: 10/21/2013] [Indexed: 12/17/2022] Open
Abstract
Though operationally defined as cis-regulatory elements, enhancers can also communicate with promoters on a separate homolog in trans, a mechanism that has been suggested to account for the ability of certain alleles of the same gene to complement one another in a process otherwise known as transvection. This homolog-pairing dependent process is facilitated in Drosophila by chromatin-associated pairing proteins, many of which remain unknown and their mechanism of action uncharacterized. Here we have tested the role of the gypsy chromatin insulator in facilitating pairing and communication between enhancers and promoters in trans using a transgenic eGFP reporter system engineered to allow for targeted deletions in the vestigial Boundary Enhancer (vgBE) and the hsp70 minimal promoter, along with one or two flanking gypsy elements. We found a modest 2.5-3x increase in eGFP reporter levels from homozygotes carrying an intact copy of the reporter on each homolog compared to unpaired hemizygotes, although this behavior was independent of gypsy. However, detectable levels of GFP protein along the DV wing boundary in trans-heterozygotes lacking a single enhancer and promoter was only observed in the presence of two flanking gypsy elements. Our results demonstrate that gypsy can stimulate enhancer-promoter communication in trans throughout the genome in a context-dependent manner, likely through modulation of local chromatin dynamics once pairing has been established by other elements and highlights chromatin structure as the master regulator of this phenomenon.
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Affiliation(s)
- Todd Schoborg
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee, United States of America
| | - Srilalitha Kuruganti
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee, United States of America
| | - Ryan Rickels
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee, United States of America
| | - Mariano Labrador
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee, United States of America
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Kirchmaier S, Höckendorf B, Möller EK, Bornhorst D, Spitz F, Wittbrodt J. Efficient site-specific transgenesis and enhancer activity tests in medaka using PhiC31 integrase. Development 2013; 140:4287-95. [PMID: 24048591 PMCID: PMC3809364 DOI: 10.1242/dev.096081] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Established transgenesis methods for fish model systems allow efficient genomic integration of transgenes. However, thus far a way of controlling copy number and integration sites has not been available, leading to variable transgene expression caused by position effects. The integration of transgenes at predefined genomic positions enables the direct comparison of different transgenes, thereby improving time and cost efficiency. Here, we report an efficient PhiC31-based site-specific transgenesis system for medaka. This system includes features that allow the pre-selection of successfully targeted integrations early on in the injected generation. Pre-selected embryos transmit the correctly integrated transgene through the germline with high efficiency. The landing site design enables a variety of applications, such as reporter and enhancer switch, in addition to the integration of any insert. Importantly, this allows assaying of enhancer activity in a site-specific manner without requiring germline transmission, thus speeding up large-scale analyses of regulatory elements.
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Affiliation(s)
- Stephan Kirchmaier
- Centre for Organismal Studies, Heidelberg University, 69120 Heidelberg, Germany
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Harmston N, Lenhard B. Chromatin and epigenetic features of long-range gene regulation. Nucleic Acids Res 2013; 41:7185-99. [PMID: 23766291 PMCID: PMC3753629 DOI: 10.1093/nar/gkt499] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The precise regulation of gene transcription during metazoan development is controlled by a complex system of interactions between transcription factors, histone modifications and modifying enzymes and chromatin conformation. Developments in chromosome conformation capture technologies have revealed that interactions between regions of chromatin are pervasive and highly cell-type specific. The movement of enhancers and promoters in and out of higher-order chromatin structures within the nucleus are associated with changes in expression and histone modifications. However, the factors responsible for mediating these changes and determining enhancer:promoter specificity are still not completely known. In this review, we summarize what is known about the patterns of epigenetic and chromatin features characteristic of elements involved in long-range interactions. In addition, we review the insights into both local and global patterns of chromatin interactions that have been revealed by the latest experimental and computational methods.
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Affiliation(s)
- Nathan Harmston
- MRC Clinical Sciences Centre, Faculty of Medicine, Imperial College, London W12 0NN, UK, Institute of Clinical Sciences, Faculty of Medicine, Imperial College, London W12 0NN, UK and Department of Informatics, University of Bergen, Thromøhlensgate 55, N-5008 Bergen, Norway
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38
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Recombinase-mediated cassette exchange (RMCE) — A rapidly-expanding toolbox for targeted genomic modifications. Gene 2013. [DOI: 10.1016/j.gene.2012.11.016] [Citation(s) in RCA: 111] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Transvection in 2012: site-specific transgenes reveal a plethora of trans-regulatory effects. Genetics 2012; 191:1037-9. [PMID: 22879406 DOI: 10.1534/genetics.112.142893] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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40
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Captured segment exchange: a strategy for custom engineering large genomic regions in Drosophila melanogaster. Genetics 2012; 193:421-30. [PMID: 23150604 DOI: 10.1534/genetics.112.145748] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Site-specific recombinases (SSRs) are valuable tools for manipulating genomes. In Drosophila, thousands of transgenic insertions carrying SSR recognition sites have been distributed throughout the genome by several large-scale projects. Here we describe a method with the potential to use these insertions to make custom alterations to the Drosophila genome in vivo. Specifically, by employing recombineering techniques and a dual recombinase-mediated cassette exchange strategy based on the phiC31 integrase and FLP recombinase, we show that a large genomic segment that lies between two SSR recognition-site insertions can be "captured" as a target cassette and exchanged for a sequence that was engineered in bacterial cells. We demonstrate this approach by targeting a 50-kb segment spanning the tsh gene, replacing the existing segment with corresponding recombineered sequences through simple and efficient manipulations. Given the high density of SSR recognition-site insertions in Drosophila, our method affords a straightforward and highly efficient approach to explore gene function in situ for a substantial portion of the Drosophila genome.
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