1
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Wenger A, Biran A, Alcaraz N, Redó-Riveiro A, Sell AC, Krautz R, Flury V, Reverón-Gómez N, Solis-Mezarino V, Völker-Albert M, Imhof A, Andersson R, Brickman JM, Groth A. Symmetric inheritance of parental histones governs epigenome maintenance and embryonic stem cell identity. Nat Genet 2023; 55:1567-1578. [PMID: 37666988 PMCID: PMC10484787 DOI: 10.1038/s41588-023-01476-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 07/17/2023] [Indexed: 09/06/2023]
Abstract
Modified parental histones are segregated symmetrically to daughter DNA strands during replication and can be inherited through mitosis. How this may sustain the epigenome and cell identity remains unknown. Here we show that transmission of histone-based information during DNA replication maintains epigenome fidelity and embryonic stem cell plasticity. Asymmetric segregation of parental histones H3-H4 in MCM2-2A mutants compromised mitotic inheritance of histone modifications and globally altered the epigenome. This included widespread spurious deposition of repressive modifications, suggesting elevated epigenetic noise. Moreover, H3K9me3 loss at repeats caused derepression and H3K27me3 redistribution across bivalent promoters correlated with misexpression of developmental genes. MCM2-2A mutation challenged dynamic transitions in cellular states across the cell cycle, enhancing naïve pluripotency and reducing lineage priming in G1. Furthermore, developmental competence was diminished, correlating with impaired exit from pluripotency. Collectively, this argues that epigenetic inheritance of histone modifications maintains a correctly balanced and dynamic chromatin landscape able to support mammalian cell differentiation.
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Affiliation(s)
- Alice Wenger
- Novo Nordisk Foundation Center for Protein Research (CPR), University of Copenhagen, Copenhagen, Denmark
- Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Copenhagen, Denmark
- Lexogen GmbH, Vienna, Austria
| | - Alva Biran
- Novo Nordisk Foundation Center for Protein Research (CPR), University of Copenhagen, Copenhagen, Denmark
- Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Copenhagen, Denmark
| | - Nicolas Alcaraz
- Novo Nordisk Foundation Center for Protein Research (CPR), University of Copenhagen, Copenhagen, Denmark
- Section for Computational and RNA Biology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Alba Redó-Riveiro
- Novo Nordisk Foundation Center for Stem Cell Medicine (reNEW), University of Copenhagen, Copenhagen, Denmark
| | - Annika Charlotte Sell
- Novo Nordisk Foundation Center for Stem Cell Medicine (reNEW), University of Copenhagen, Copenhagen, Denmark
| | - Robert Krautz
- Section for Computational and RNA Biology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Valentin Flury
- Novo Nordisk Foundation Center for Protein Research (CPR), University of Copenhagen, Copenhagen, Denmark
- Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Copenhagen, Denmark
| | - Nazaret Reverón-Gómez
- Novo Nordisk Foundation Center for Protein Research (CPR), University of Copenhagen, Copenhagen, Denmark
- Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Copenhagen, Denmark
| | | | - Moritz Völker-Albert
- EpiQMAx GmbH, Planegg, Germany
- Faculty of Medicine, Biomedical Center, Protein Analysis Unit, Ludwig-Maximilians-Universität München, Planegg, Germany
| | - Axel Imhof
- Faculty of Medicine, Biomedical Center, Protein Analysis Unit, Ludwig-Maximilians-Universität München, Planegg, Germany
| | - Robin Andersson
- Section for Computational and RNA Biology, Department of Biology, University of Copenhagen, Copenhagen, Denmark.
- The Novo Nordisk Foundation Center for Genomic Mechanisms of Disease, Broad Institute of MIT and Harvard, Cambridge, MA, USA.
| | - Joshua M Brickman
- Novo Nordisk Foundation Center for Stem Cell Medicine (reNEW), University of Copenhagen, Copenhagen, Denmark.
| | - Anja Groth
- Novo Nordisk Foundation Center for Protein Research (CPR), University of Copenhagen, Copenhagen, Denmark.
- Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Copenhagen, Denmark.
- Department of Cellular and Molecular Medicine (ICMM), University of Copenhagen, Copenhagen, Denmark.
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2
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van Duin L, Krautz R, Rennie S, Andersson R. Transcription factor expression is the main determinant of variability in gene co-activity. Mol Syst Biol 2023:e11392. [PMID: 37158788 DOI: 10.15252/msb.202211392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 04/13/2023] [Accepted: 04/17/2023] [Indexed: 05/10/2023] Open
Abstract
Many genes are co-expressed and form genomic domains of coordinated gene activity. However, the regulatory determinants of domain co-activity remain unclear. Here, we leverage human individual variation in gene expression to characterize the co-regulatory processes underlying domain co-activity and systematically quantify their effect sizes. We employ transcriptional decomposition to extract from RNA expression data an expression component related to co-activity revealed by genomic positioning. This strategy reveals close to 1,500 co-activity domains, covering most expressed genes, of which the large majority are invariable across individuals. Focusing specifically on domains with high variability in co-activity reveals that contained genes have a higher sharing of eQTLs, a higher variability in enhancer interactions, and an enrichment of binding by variably expressed transcription factors, compared to genes within non-variable domains. Through careful quantification of the relative contributions of regulatory processes underlying co-activity, we find transcription factor expression levels to be the main determinant of gene co-activity. Our results indicate that distal trans effects contribute more than local genetic variation to individual variation in co-activity domains.
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Affiliation(s)
- Lucas van Duin
- Section for Computational and RNA Biology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Robert Krautz
- Section for Computational and RNA Biology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Sarah Rennie
- Section for Computational and RNA Biology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Robin Andersson
- Section for Computational and RNA Biology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
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3
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Tang JLY, Krautz R, Llorà-Batlle O, Hakes AE, Fox PM, Brand AH. In vivo, genome-wide profiling of endogenously tagged chromatin-binding proteins with spatial and temporal resolution using NanoDam in Drosophila. STAR Protoc 2022; 3:101788. [PMID: 36345375 PMCID: PMC9636480 DOI: 10.1016/j.xpro.2022.101788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
NanoDam is a technique for genome-wide profiling of the binding targets of any endogenously tagged chromatin-binding protein in vivo, without the need for antibodies, crosslinking, or immunoprecipitation. Here, we explain the procedure for NanoDam experiments in Drosophila, starting from a genetic cross, to the generation of sequencing libraries and, finally, bioinformatic analysis. This protocol can be readily adapted for use in other model systems after simple modifications. For complete details on the use and execution of this protocol, please refer to Tang et al. (2022).
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Affiliation(s)
- Jocelyn L Y Tang
- Gurdon Institute and Department of Physiology, Development and Neuroscience, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
| | - Robert Krautz
- Gurdon Institute and Department of Physiology, Development and Neuroscience, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
| | - Oriol Llorà-Batlle
- Gurdon Institute and Department of Physiology, Development and Neuroscience, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
| | - Anna E Hakes
- Gurdon Institute and Department of Physiology, Development and Neuroscience, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
| | - Paul M Fox
- Gurdon Institute and Department of Physiology, Development and Neuroscience, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
| | - Andrea H Brand
- Gurdon Institute and Department of Physiology, Development and Neuroscience, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK.
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4
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Tang JLY, Hakes AE, Krautz R, Suzuki T, Contreras EG, Fox PM, Brand AH. NanoDam identifies Homeobrain (ARX) and Scarecrow (NKX2.1) as conserved temporal factors in the Drosophila central brain and visual system. Dev Cell 2022; 57:1193-1207.e7. [PMID: 35483359 DOI: 10.1016/j.devcel.2022.04.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 02/08/2022] [Accepted: 04/05/2022] [Indexed: 11/24/2022]
Abstract
Temporal patterning of neural progenitors is an evolutionarily conserved strategy for generating neuronal diversity. Type II neural stem cells in the Drosophila central brain produce transit-amplifying intermediate neural progenitors (INPs) that exhibit temporal patterning. However, the known temporal factors cannot account for the neuronal diversity in the adult brain. To search for missing factors, we developed NanoDam, which enables rapid genome-wide profiling of endogenously tagged proteins in vivo with a single genetic cross. Mapping the targets of known temporal transcription factors with NanoDam revealed that Homeobrain and Scarecrow (ARX and NKX2.1 orthologs) are also temporal factors. We show that Homeobrain and Scarecrow define middle-aged and late INP temporal windows and play a role in cellular longevity. Strikingly, Homeobrain and Scarecrow have conserved functions as temporal factors in the developing visual system. NanoDam enables rapid cell-type-specific genome-wide profiling with temporal resolution and is easily adapted for use in higher organisms.
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Affiliation(s)
- Jocelyn L Y Tang
- Gurdon Institute and Department of Physiology, Development and Neuroscience, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
| | - Anna E Hakes
- Gurdon Institute and Department of Physiology, Development and Neuroscience, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
| | - Robert Krautz
- Gurdon Institute and Department of Physiology, Development and Neuroscience, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
| | - Takumi Suzuki
- Gurdon Institute and Department of Physiology, Development and Neuroscience, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
| | - Esteban G Contreras
- Gurdon Institute and Department of Physiology, Development and Neuroscience, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
| | - Paul M Fox
- Gurdon Institute and Department of Physiology, Development and Neuroscience, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
| | - Andrea H Brand
- Gurdon Institute and Department of Physiology, Development and Neuroscience, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK.
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Bakoulis S, Krautz R, Alcaraz N, Salvatore M, Andersson R. OUP accepted manuscript. Nucleic Acids Res 2022; 50:2111-2127. [PMID: 35166831 PMCID: PMC8887488 DOI: 10.1093/nar/gkac088] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 01/22/2022] [Accepted: 01/27/2022] [Indexed: 11/12/2022] Open
Affiliation(s)
| | | | - Nicolas Alcaraz
- The Bioinformatics Centre, Department of Biology, University of Copenhagen, 2200 Copenhagen, Denmark
- Novo Nordisk Foundation Center for Protein Research (CPR), University of Copenhagen, 2200 Copenhagen, Denmark
| | - Marco Salvatore
- The Bioinformatics Centre, Department of Biology, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Robin Andersson
- To whom correspondence should be addressed. Tel: +45 35330245;
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Krautz R, Khalili D, Theopold U. Tissue-autonomous immune response regulates stress signaling during hypertrophy. eLife 2020; 9:64919. [PMID: 33377870 PMCID: PMC7880693 DOI: 10.7554/elife.64919] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Accepted: 12/29/2020] [Indexed: 12/19/2022] Open
Abstract
Postmitotic tissues are incapable of replacing damaged cells through proliferation, but need to rely on buffering mechanisms to prevent tissue disintegration. By constitutively activating the Ras/MAPK-pathway via RasV12-overexpression in the postmitotic salivary glands (SGs) of Drosophila larvae, we overrode the glands adaptability to growth signals and induced hypertrophy. The accompanied loss of tissue integrity, recognition by cellular immunity, and cell death are all buffered by blocking stress signaling through a genuine tissue-autonomous immune response. This novel, spatio-temporally tightly regulated mechanism relies on the inhibition of a feedback-loop in the JNK-pathway by the immune effector and antimicrobial peptide Drosomycin. While this interaction might allow growing SGs to cope with temporary stress, continuous Drosomycin expression in RasV12-glands favors unrestricted hypertrophy. These findings indicate the necessity to refine therapeutic approaches that stimulate immune responses by acknowledging their possible, detrimental effects in damaged or stressed tissues. Tissues and organs work hard to maintain balance in everything from taking up nutrients to controlling their growth. Ageing, wounding, sickness, and changes in the genetic code can all alter this balance, and cause the tissue or organ to lose some of its cells. Many tissues restore this loss by dividing their remaining cells to fill in the gaps. But some – like the salivary glands of fruit fly larvae – have lost this ability. Tissues like these rely on being able to sense and counteract problems as they arise so as to not lose their balance in the first place. The immune system and stress responses are crucial for this process. They trigger steps to correct the problem and interact with each other to find a common decision about the fate of the affected tissue. To better understand how the immune system and stress response work together, Krautz, Khalili and Theopold genetically manipulated cells in the salivary gland of fruit fly larvae. These modifications switched on signals that stimulate cells to keep growing, causing the salivary gland’s tissue to slowly lose its balance and trigger the stress and immune response. The experiments showed that while the stress response instructed the cells in the gland to die, a peptide released by the immune system called Drosomycin blocked this response and prevented the tissue from collapsing. The cells in the part of the gland not producing this immune peptide were consequently killed by the stress response. When all the cells in the salivary gland were forced to produce Drosomycin, none of the cells died and the whole tissue survived. But it also allowed the cells in the gland to grow uncontrollably, like a tumor, threatening the health of the entire organism. Mapping the interactions between immune and stress pathways could help to fine-tune treatments that can prevent tissue damage. Fruit flies share many genetic features and molecular pathways with humans. So, the next step towards these kinds of treatments would be to screen for similar mechanisms that block stress activation in damaged human tissues. But this research carries a warning: careless activation of the immune system to protect stressed tissues could lead to uncontrolled tissue growth, and might cause more harm than good.
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Affiliation(s)
- Robert Krautz
- Department of Molecular Biosciences, The Wenner-Gren Institute (MBW), Stockholm University, Stockholm, Sweden
| | - Dilan Khalili
- Department of Molecular Biosciences, The Wenner-Gren Institute (MBW), Stockholm University, Stockholm, Sweden
| | - Ulrich Theopold
- Department of Molecular Biosciences, The Wenner-Gren Institute (MBW), Stockholm University, Stockholm, Sweden
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7
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Dziedziech A, Schmid M, Arefin B, Kienzle T, Krautz R, Theopold U. Data on Drosophila clots and hemocyte morphologies using GFP-tagged secretory proteins: Prophenoloxidase and transglutaminase. Data Brief 2019; 25:104229. [PMID: 31367663 PMCID: PMC6646922 DOI: 10.1016/j.dib.2019.104229] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 06/20/2019] [Accepted: 07/01/2019] [Indexed: 11/09/2022] Open
Abstract
Insect hemolymph coagulation: Kinetics of classically and non-classically secreted clotting factors Schmid et al., 2019. The linked article demonstrates the localization of two secretory proteins in Drosophila melanogaster, Prophenoloxidase (PPO2) and Transglutaminase-A (Tg) in hemocytes as well the clot with different tissue-specific drivers. Here we provide further data for the usefulness of the GFP-tagged version of the two crosslinking enzymes that are involved in clot hardening. The morphology of crystal cells is described using GFP-tagged PPO2 rather than with the use of antibodies in ex vivo hemolymph preparations. The use of the GFP-tagged proteins PPO2 and Tg is shown in additional contexts.
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Affiliation(s)
- Alexis Dziedziech
- Stockholm University, Department of Molecular Biosciences, Svante Arrhenius Väg 20C, SE, 10691 Sweden
| | - Martin Schmid
- Stockholm University, Department of Molecular Biosciences, Svante Arrhenius Väg 20C, SE, 10691 Sweden
| | - Badrul Arefin
- Stockholm University, Department of Molecular Biosciences, Svante Arrhenius Väg 20C, SE, 10691 Sweden
| | - Thomas Kienzle
- Stockholm University, Department of Molecular Biosciences, Svante Arrhenius Väg 20C, SE, 10691 Sweden
| | - Robert Krautz
- Stockholm University, Department of Molecular Biosciences, Svante Arrhenius Väg 20C, SE, 10691 Sweden
| | - Ulrich Theopold
- Stockholm University, Department of Molecular Biosciences, Svante Arrhenius Väg 20C, SE, 10691 Sweden
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8
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Cheetham SW, Gruhn WH, van den Ameele J, Krautz R, Southall TD, Kobayashi T, Surani MA, Brand AH. Targeted DamID reveals differential binding of mammalian pluripotency factors. Development 2018; 145:dev.170209. [PMID: 30185410 DOI: 10.1242/dev.170209] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Accepted: 08/23/2018] [Indexed: 12/14/2022]
Abstract
The precise control of gene expression by transcription factor networks is crucial to organismal development. The predominant approach for mapping transcription factor-chromatin interactions has been chromatin immunoprecipitation (ChIP). However, ChIP requires a large number of homogeneous cells and antisera with high specificity. A second approach, DamID, has the drawback that high levels of Dam methylase are toxic. Here, we modify our targeted DamID approach (TaDa) to enable cell type-specific expression in mammalian systems, generating an inducible system (mammalian TaDa or MaTaDa) to identify genome-wide protein/DNA interactions in 100 to 1000 times fewer cells than ChIP-based approaches. We mapped the binding sites of two key pluripotency factors, OCT4 and PRDM14, in mouse embryonic stem cells, epiblast-like cells and primordial germ cell-like cells (PGCLCs). PGCLCs are an important system for elucidating primordial germ cell development in mice. We monitored PRDM14 binding during the specification of PGCLCs, identifying direct targets of PRDM14 that are key to understanding its crucial role in PGCLC development. We show that MaTaDa is a sensitive and accurate method for assessing cell type-specific transcription factor binding in limited numbers of cells.
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Affiliation(s)
- Seth W Cheetham
- The Gurdon Institute and Department of Physiology, Development and Neuroscience, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
| | - Wolfram H Gruhn
- The Gurdon Institute and Department of Physiology, Development and Neuroscience, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
| | - Jelle van den Ameele
- The Gurdon Institute and Department of Physiology, Development and Neuroscience, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
| | - Robert Krautz
- The Gurdon Institute and Department of Physiology, Development and Neuroscience, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
| | - Tony D Southall
- The Gurdon Institute and Department of Physiology, Development and Neuroscience, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
| | - Toshihiro Kobayashi
- The Gurdon Institute and Department of Physiology, Development and Neuroscience, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
| | - M Azim Surani
- The Gurdon Institute and Department of Physiology, Development and Neuroscience, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
| | - Andrea H Brand
- The Gurdon Institute and Department of Physiology, Development and Neuroscience, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
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9
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Hauptmann G, Söll I, Krautz R, Theopold U. Multi-target Chromogenic Whole-mount In Situ Hybridization for Comparing Gene Expression Domains in Drosophila Embryos. J Vis Exp 2016:e53830. [PMID: 26862978 PMCID: PMC4781704 DOI: 10.3791/53830] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
To analyze gene regulatory networks active during embryonic development and organogenesis it is essential to precisely define how the different genes are expressed in spatial relation to each other in situ. Multi-target chromogenic whole-mount in situ hybridization (MC-WISH) greatly facilitates the instant comparison of gene expression patterns, as it allows distinctive visualization of different mRNA species in contrasting colors in the same sample specimen. This provides the possibility to relate gene expression domains topographically to each other with high accuracy and to define unique and overlapping expression sites. In the presented protocol, we describe a MC-WISH procedure for comparing mRNA expression patterns of different genes in Drosophila embryos. Up to three RNA probes, each specific for another gene and labeled by a different hapten, are simultaneously hybridized to the embryo samples and subsequently detected by alkaline phosphatase-based colorimetric immunohistochemistry. The described procedure is detailed here for Drosophila, but works equally well with zebrafish embryos.
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Affiliation(s)
- Giselbert Hauptmann
- Department of Molecular Biosciences, The Wenner-Gren Institute (MBW), Stockholm University;
| | - Iris Söll
- Department of Molecular Biosciences, The Wenner-Gren Institute (MBW), Stockholm University
| | - Robert Krautz
- Department of Molecular Biosciences, The Wenner-Gren Institute (MBW), Stockholm University
| | - Ulrich Theopold
- Department of Molecular Biosciences, The Wenner-Gren Institute (MBW), Stockholm University
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10
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Papadopoulos DK, Krmpot AJ, Nikolić SN, Krautz R, Terenius L, Tomancak P, Rigler R, Gehring WJ, Vukojević V. Probing the kinetic landscape of Hox transcription factor-DNA binding in live cells by massively parallel Fluorescence Correlation Spectroscopy. Mech Dev 2015; 138 Pt 2:218-225. [PMID: 26428533 DOI: 10.1016/j.mod.2015.09.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Revised: 09/23/2015] [Accepted: 09/24/2015] [Indexed: 11/25/2022]
Abstract
Hox genes encode transcription factors that control the formation of body structures, segment-specifically along the anterior-posterior axis of metazoans. Hox transcription factors bind nuclear DNA pervasively and regulate a plethora of target genes, deploying various molecular mechanisms that depend on the developmental and cellular context. To analyze quantitatively the dynamics of their DNA-binding behavior we have used confocal laser scanning microscopy (CLSM), single-point fluorescence correlation spectroscopy (FCS), fluorescence cross-correlation spectroscopy (FCCS) and bimolecular fluorescence complementation (BiFC). We show that the Hox transcription factor Sex combs reduced (Scr) forms dimers that strongly associate with its specific fork head binding site (fkh250) in live salivary gland cell nuclei. In contrast, dimers of a constitutively inactive, phospho-mimicking variant of Scr show weak, non-specific DNA-binding. Our studies reveal that nuclear dynamics of Scr is complex, exhibiting a changing landscape of interactions that is difficult to characterize by probing one point at a time. Therefore, we also provide mechanistic evidence using massively parallel FCS (mpFCS). We found that Scr dimers are predominantly formed on the DNA and are equally abundant at the chromosomes and an introduced multimeric fkh250 binding-site, indicating different mobilities, presumably reflecting transient binding with different affinities on the DNA. Our proof-of-principle results emphasize the advantages of mpFCS for quantitative characterization of fast dynamic processes in live cells.
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Affiliation(s)
| | - Aleksandar J Krmpot
- Department of Clinical Neuroscience (CNS), Center for Molecular Medicine (CMM), Karolinska Institutet, 17176 Stockholm, Sweden; Institute of Physics, University of Belgrade, 11080 Belgrade, Serbia
| | - Stanko N Nikolić
- Department of Clinical Neuroscience (CNS), Center for Molecular Medicine (CMM), Karolinska Institutet, 17176 Stockholm, Sweden; Institute of Physics, University of Belgrade, 11080 Belgrade, Serbia
| | - Robert Krautz
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 10691 Stockholm, Sweden
| | - Lars Terenius
- Department of Clinical Neuroscience (CNS), Center for Molecular Medicine (CMM), Karolinska Institutet, 17176 Stockholm, Sweden
| | - Pavel Tomancak
- Max-Planck Institute for Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Rudolf Rigler
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 17177 Stockholm, Sweden; Laboratory of Biomedical Optics, Swiss Federal Institute of Technology, 1015 Lausanne, Switzerland
| | - Walter J Gehring
- Department of Cell Biology, Biozentrum, University of Basel, 4056 Basel, Switzerland
| | - Vladana Vukojević
- Department of Clinical Neuroscience (CNS), Center for Molecular Medicine (CMM), Karolinska Institutet, 17176 Stockholm, Sweden.
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11
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Arefin B, Kucerova L, Krautz R, Kranenburg H, Parvin F, Theopold U. Apoptosis in Hemocytes Induces a Shift in Effector Mechanisms in the Drosophila Immune System and Leads to a Pro-Inflammatory State. PLoS One 2015; 10:e0136593. [PMID: 26322507 PMCID: PMC4555835 DOI: 10.1371/journal.pone.0136593] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Accepted: 08/05/2015] [Indexed: 12/21/2022] Open
Abstract
Apart from their role in cellular immunity via phagocytosis and encapsulation, Drosophila hemocytes release soluble factors such as antimicrobial peptides, and cytokines to induce humoral responses. In addition, they participate in coagulation and wounding, and in development. To assess their role during infection with entomopathogenic nematodes, we depleted plasmatocytes and crystal cells, the two classes of hemocytes present in naïve larvae by expressing proapoptotic proteins in order to produce hemocyte-free (Hml-apo, originally called Hemoless) larvae. Surprisingly, we found that Hml-apo larvae are still resistant to nematode infections. When further elucidating the immune status of Hml-apo larvae, we observe a shift in immune effector pathways including massive lamellocyte differentiation and induction of Toll- as well as repression of imd signaling. This leads to a pro-inflammatory state, characterized by the appearance of melanotic nodules in the hemolymph and to strong developmental defects including pupal lethality and leg defects in escapers. Further analysis suggests that most of the phenotypes we observe in Hml-apo larvae are alleviated by administration of antibiotics and by changing the food source indicating that they are mediated through the microbiota. Biochemical evidence identifies nitric oxide as a key phylogenetically conserved regulator in this process. Finally we show that the nitric oxide donor L-arginine similarly modifies the response against an early stage of tumor development in fly larvae.
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Affiliation(s)
- Badrul Arefin
- Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Lucie Kucerova
- Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Robert Krautz
- Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | | | - Farjana Parvin
- Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Ulrich Theopold
- Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
- * E-mail:
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12
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Abstract
Insects and mammals share an ancient innate immune system comprising both humoral and cellular responses. The insect immune system consists of the fat body, which secretes effector molecules into the hemolymph and several classes of hemocytes, which reside in the hemolymph and of protective border epithelia. Key features of wound- and immune responses are shared between insect and mammalian immune systems including the mode of activation by commonly shared microbial (non-self) patterns and the recognition of these patterns by dedicated receptors. It is unclear how metazoan parasites in insects, which lack these shared motifs, are recognized. Research in recent years has demonstrated that during entry into the insect host, many eukaryotic pathogens leave traces that alert potential hosts of the damage they have afflicted. In accordance with terminology used in the mammalian immune systems, these signals have been dubbed danger- or damage-associated signals. Damage signals are necessary byproducts generated during entering hosts either by mechanical or proteolytic damage. Here, we briefly review the current stage of knowledge on how wound closure and wound healing during mechanical damage is regulated and how damage-related signals contribute to these processes. We also discuss how sensors of proteolytic activity induce insect innate immune responses. Strikingly damage-associated signals are also released from cells that have aberrant growth, including tumor cells. These signals may induce apoptosis in the damaged cells, the recruitment of immune cells to the aberrant tissue and even activate humoral responses. Thus, this ensures the removal of aberrant cells and compensatory proliferation to replace lost tissue. Several of these pathways may have been co-opted from wound healing and developmental processes.
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Affiliation(s)
| | | | - Ulrich Theopold
- *Correspondence: Ulrich Theopold, Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, Svante Arrheniusväg 20C, Stockholm, Sweden e-mail:
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Abstract
Our goal is to characterize the innate immune response against the early stage of tumor development. For this, animal models where genetic changes in specific cells and tissues can be performed in a controlled way have become increasingly important, including the fruitfly Drosophila melanogaster. Many tumor mutants in Drosophila affect the germline and, as a consequence, also the immune system itself, making it difficult to ascribe their phenotype to a specific tissue. Only during the past decade, mutations have been induced systematically in somatic cells to study the control of tumorous growth by neighboring cells and by immune cells. Here we show that upon ectopic expression of a dominant-active form of the Ras oncogene (RasV12), both imaginal discs and salivary glands are affected. Particularly, the glands increase in size, express metalloproteinases and display apoptotic markers. This leads to a strong cellular response, which has many hallmarks of the granuloma-like encapsulation reaction, usually mounted by the insect against larger foreign objects. RNA sequencing of the fat body reveals a characteristic humoral immune response. In addition we also identify genes that are specifically induced upon expression of RasV12. As a proof-of-principle, we show that one of the induced genes (santa-maria), which encodes a scavenger receptor, modulates damage to the salivary glands. The list of genes we have identified provides a rich source for further functional characterization. Our hope is that this will lead to a better understanding of the earliest stage of innate immune responses against tumors with implications for mammalian immunity.
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Affiliation(s)
- Thomas Hauling
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, S-10691 Stockholm, Sweden
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14
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Theopold U, Krautz R, Dushay MS. The Drosophila clotting system and its messages for mammals. Dev Comp Immunol 2014; 42:42-46. [PMID: 23545286 DOI: 10.1016/j.dci.2013.03.014] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Revised: 03/07/2013] [Accepted: 03/24/2013] [Indexed: 06/02/2023]
Abstract
Drosophila has been increasingly used as a model to study hemolymph clotting. Proteomics and bioinformatics identified candidate clotting-factors, several of which were tested using genetics. Mutants and lines with reduced expression of clotting-factors show subtle effects after wounding, indicating that sealing wounds may rely on redundant mechanisms. More striking effects are observed after infection, in particular when a natural infection model involving entomopathogenic nematodes is used. When translated into mammalian models these results reveal that mammalian blood clots serve a similar immune function, thus providing a new example of the usefulness of studying invertebrate models.
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Affiliation(s)
- Ulrich Theopold
- Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, 10691 Stockholm, Sweden.
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