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Newman T, Ishihara T, Shaw G, Renfree MB. The structure of the TH/INS locus and the parental allele expressed are not conserved between mammals. Heredity (Edinb) 2024:10.1038/s41437-024-00689-y. [PMID: 38834866 DOI: 10.1038/s41437-024-00689-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 05/01/2024] [Accepted: 05/07/2024] [Indexed: 06/06/2024] Open
Abstract
Parent-of-origin-specific expression of imprinted genes is critical for successful mammalian growth and development. Insulin, coded by the INS gene, is an important growth factor expressed from the paternal allele in the yolk sac placenta of therian mammals. The tyrosine hydroxylase gene TH encodes an enzyme involved in dopamine synthesis. TH and INS are closely associated in most vertebrates, but the mouse orthologues, Th and Ins2, are separated by repeated DNA. In mice, Th is expressed from the maternal allele, but the parental origin of expression is not known for any other mammal so it is unclear whether the maternal expression observed in the mouse represents an evolutionary divergence or an ancestral condition. We compared the length of the DNA segment between TH and INS across species and show that separation of these genes occurred in the rodent lineage with an accumulation of repeated DNA. We found that the region containing TH and INS in the tammar wallaby produces at least five distinct RNA transcripts: TH, TH-INS1, TH-INS2, lncINS and INS. Using allele-specific expression analysis, we show that the TH/INS locus is expressed from the paternal allele in pre- and postnatal tammar wallaby tissues. Determining the imprinting pattern of TH/INS in other mammals might clarify if paternal expression is the ancestral condition which has been flipped to maternal expression in rodents by the accumulation of repeat sequences.
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Affiliation(s)
- Trent Newman
- School of BioSciences, The University of Melbourne, Melbourne, VIC, Australia
| | - Teruhito Ishihara
- School of BioSciences, The University of Melbourne, Melbourne, VIC, Australia
- Epigenetics Programme, Babraham Institute, Cambridge, CB22 3AT, UK
| | - Geoff Shaw
- School of BioSciences, The University of Melbourne, Melbourne, VIC, Australia
| | - Marilyn B Renfree
- School of BioSciences, The University of Melbourne, Melbourne, VIC, Australia.
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2
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Zehentner B, Scherer S, Neuhaus K. Non-canonical transcriptional start sites in E. coli O157:H7 EDL933 are regulated and appear in surprisingly high numbers. BMC Microbiol 2023; 23:243. [PMID: 37653502 PMCID: PMC10469882 DOI: 10.1186/s12866-023-02988-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 08/21/2023] [Indexed: 09/02/2023] Open
Abstract
Analysis of genome wide transcription start sites (TSSs) revealed an unexpected complexity since not only canonical TSS of annotated genes are recognized by RNA polymerase. Non-canonical TSS were detected antisense to, or within, annotated genes as well new intergenic (orphan) TSS, not associated with known genes. Previously, it was hypothesized that many such signals represent noise or pervasive transcription, not associated with a biological function. Here, a modified Cappable-seq protocol allows determining the primary transcriptome of the enterohemorrhagic E. coli O157:H7 EDL933 (EHEC). We used four different growth media, both in exponential and stationary growth phase, replicated each thrice. This yielded 19,975 EHEC canonical and non-canonical TSS, which reproducibly occurring in three biological replicates. This questions the hypothesis of experimental noise or pervasive transcription. Accordingly, conserved promoter motifs were found upstream indicating proper TSSs. More than 50% of 5,567 canonical and between 32% and 47% of 10,355 non-canonical TSS were differentially expressed in different media and growth phases, providing evidence for a potential biological function also of non-canonical TSS. Thus, reproducible and environmentally regulated expression suggests that a substantial number of the non-canonical TSSs may be of unknown function rather than being the result of noise or pervasive transcription.
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Affiliation(s)
- Barbara Zehentner
- Chair for Microbial Ecology, TUM School of Life Sciences, Department of Molecular Life Sciences, Technical University of Munich, Freising, Germany
| | - Siegfried Scherer
- Chair for Microbial Ecology, TUM School of Life Sciences, Department of Molecular Life Sciences, Technical University of Munich, Freising, Germany
- ZIEL - Institute for Food & Health, Technical University of Munich, Freising, Germany
| | - Klaus Neuhaus
- ZIEL - Institute for Food & Health, Technical University of Munich, Freising, Germany.
- Core Facility Microbiome, ZIEL - Institute for Food & Health, Technical University of Munich, Freising, Germany.
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3
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Alvarez V, Bandau S, Jiang H, Rios-Szwed D, Hukelmann J, Garcia-Wilson E, Wiechens N, Griesser E, Ten Have S, Owen-Hughes T, Lamond A, Alabert C. Proteomic profiling reveals distinct phases to the restoration of chromatin following DNA replication. Cell Rep 2023; 42:111996. [PMID: 36680776 DOI: 10.1016/j.celrep.2023.111996] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2022] [Revised: 08/12/2022] [Accepted: 01/03/2023] [Indexed: 01/21/2023] Open
Abstract
Chromatin organization must be maintained during cell proliferation to preserve cellular identity and genome integrity. However, DNA replication results in transient displacement of DNA-bound proteins, and it is unclear how they regain access to newly replicated DNA. Using quantitative proteomics coupled to Nascent Chromatin Capture or isolation of Proteins on Nascent DNA, we provide time-resolved binding kinetics for thousands of proteins behind replisomes within euchromatin and heterochromatin in human cells. This shows that most proteins regain access within minutes to newly replicated DNA. In contrast, 25% of the identified proteins do not, and this delay cannot be inferred from their known function or nuclear abundance. Instead, chromatin organization and G1 phase entry affect their reassociation. Finally, DNA replication not only disrupts but also promotes recruitment of transcription factors and chromatin remodelers, providing a significant advance in understanding how DNA replication could contribute to programmed changes of cell memory.
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Affiliation(s)
- Vanesa Alvarez
- Division of Molecular, Cell, and Developmental Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, UK
| | - Susanne Bandau
- Division of Molecular, Cell, and Developmental Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, UK
| | - Hao Jiang
- Laboratory of Quantitative Proteomics, Division of Molecular, Cell, and Developmental Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, UK
| | - Diana Rios-Szwed
- Division of Molecular, Cell, and Developmental Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, UK
| | - Jens Hukelmann
- Laboratory of Quantitative Proteomics, Division of Molecular, Cell, and Developmental Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, UK
| | - Elisa Garcia-Wilson
- Division of Molecular, Cell, and Developmental Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, UK
| | - Nicola Wiechens
- Laboratory of Chromatin Remodelling and Cancer Epigenetics, Division of Molecular, Cell & Developmental Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, UK
| | - Eva Griesser
- Laboratory of Quantitative Proteomics, Division of Molecular, Cell, and Developmental Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, UK
| | - Sara Ten Have
- Laboratory of Quantitative Proteomics, Division of Molecular, Cell, and Developmental Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, UK
| | - Tom Owen-Hughes
- Laboratory of Chromatin Remodelling and Cancer Epigenetics, Division of Molecular, Cell & Developmental Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, UK
| | - Angus Lamond
- Laboratory of Quantitative Proteomics, Division of Molecular, Cell, and Developmental Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, UK
| | - Constance Alabert
- Division of Molecular, Cell, and Developmental Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, UK.
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4
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Galupa R, Alvarez-Canales G, Borst NO, Fuqua T, Gandara L, Misunou N, Richter K, Alves MRP, Karumbi E, Perkins ML, Kocijan T, Rushlow CA, Crocker J. Enhancer architecture and chromatin accessibility constrain phenotypic space during Drosophila development. Dev Cell 2023; 58:51-62.e4. [PMID: 36626871 PMCID: PMC9860173 DOI: 10.1016/j.devcel.2022.12.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 10/18/2022] [Accepted: 12/07/2022] [Indexed: 01/11/2023]
Abstract
Developmental enhancers bind transcription factors and dictate patterns of gene expression during development. Their molecular evolution can underlie phenotypical evolution, but the contributions of the evolutionary pathways involved remain little understood. Here, using mutation libraries in Drosophila melanogaster embryos, we observed that most point mutations in developmental enhancers led to changes in gene expression levels but rarely resulted in novel expression outside of the native pattern. In contrast, random sequences, often acting as developmental enhancers, drove expression across a range of cell types; random sequences including motifs for transcription factors with pioneer activity acted as enhancers even more frequently. Our findings suggest that the phenotypic landscapes of developmental enhancers are constrained by enhancer architecture and chromatin accessibility. We propose that the evolution of existing enhancers is limited in its capacity to generate novel phenotypes, whereas the activity of de novo elements is a primary source of phenotypic novelty.
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Affiliation(s)
- Rafael Galupa
- European Molecular Biology Laboratory, 69117 Heidelberg, Germany.
| | | | | | - Timothy Fuqua
- European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Lautaro Gandara
- European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Natalia Misunou
- European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Kerstin Richter
- European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | | | - Esther Karumbi
- European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | | | - Tin Kocijan
- European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | | | - Justin Crocker
- European Molecular Biology Laboratory, 69117 Heidelberg, Germany.
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5
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Nawaz K, Cziesielski MJ, Mariappan KG, Cui G, Aranda M. Histone modifications and DNA methylation act cooperatively in regulating symbiosis genes in the sea anemone Aiptasia. BMC Biol 2022; 20:265. [DOI: 10.1186/s12915-022-01469-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 11/17/2022] [Indexed: 12/03/2022] Open
Abstract
Abstract
Background
The symbiotic relationship between cnidarians and dinoflagellates is one of the most widespread endosymbiosis in our oceans and provides the ecological basis of coral reef ecosystems. Although many studies have been undertaken to unravel the molecular mechanisms underlying these symbioses, we still know little about the epigenetic mechanisms that control the transcriptional responses to symbiosis.
Results
Here, we used the model organism Exaiptasia diaphana to study the genome-wide patterns and putative functions of the histone modifications H3K27ac, H3K4me3, H3K9ac, H3K36me3, and H3K27me3 in symbiosis. While we find that their functions are generally conserved, we observed that colocalization of more than one modification and or DNA methylation correlated with significantly higher gene expression, suggesting a cooperative action of histone modifications and DNA methylation in promoting gene expression. Analysis of symbiosis genes revealed that activating histone modifications predominantly associated with symbiosis-induced genes involved in glucose metabolism, nitrogen transport, amino acid biosynthesis, and organism growth while symbiosis-suppressed genes were involved in catabolic processes.
Conclusions
Our results provide new insights into the mechanisms of prominent histone modifications and their interaction with DNA methylation in regulating symbiosis in cnidarians.
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Miguel-Arribas A, Wu LJ, Michaelis C, Yoshida KI, Grohmann E, Meijer WJJ. Conjugation Operons in Gram-Positive Bacteria with and without Antitermination Systems. Microorganisms 2022; 10:microorganisms10030587. [PMID: 35336162 PMCID: PMC8955417 DOI: 10.3390/microorganisms10030587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 03/03/2022] [Accepted: 03/04/2022] [Indexed: 02/01/2023] Open
Abstract
Genes involved in the same cellular process are often clustered together in an operon whose expression is controlled by an upstream promoter. Generally, the activity of the promoter is strictly controlled. However, spurious transcription undermines this strict regulation, particularly affecting large operons. The negative effects of spurious transcription can be mitigated by the presence of multiple terminators inside the operon, in combination with an antitermination system. Antitermination systems modify the transcription elongation complexes and enable them to bypass terminators. Bacterial conjugation is the process by which a conjugative DNA element is transferred from a donor to a recipient cell. Conjugation involves many genes that are mostly organized in one or a few large operons. It has recently been shown that many conjugation operons present on plasmids replicating in Gram-positive bacteria possess a bipartite antitermination system that allows not only many terminators inside the conjugation operon to be bypassed, but also the differential expression of a subset of genes. Here, we show that some conjugation operons on plasmids belonging to the Inc18 family of Gram-positive broad host-range plasmids do not possess an antitermination system, suggesting that the absence of an antitermination system may have advantages. The possible (dis)advantages of conjugation operons possessing (or not) an antitermination system are discussed.
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Affiliation(s)
- Andrés Miguel-Arribas
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Instituto de Biología Molecular Eladio Viñuela (CSIC), C. Nicolás Cabrera 1, Universidad Autónoma, Canto Blanco, 28049 Madrid, Spain;
| | - Ling Juan Wu
- Centre for Bacterial Cell Biology, Medical Faculty, Biosciences Institute, Newcastle University, Richardson Road, Newcastle upon Tyne NE2 4AX, UK;
| | - Claudia Michaelis
- School of Life Sciences and Technology, Berlin University of Applied Sciences, Seestrasse 64, 13347 Berlin, Germany;
| | - Ken-ichi Yoshida
- Department of Science, Technology and Innovation, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan;
| | - Elisabeth Grohmann
- School of Life Sciences and Technology, Berlin University of Applied Sciences, Seestrasse 64, 13347 Berlin, Germany;
- Correspondence: (E.G.); (W.J.J.M.); Tel.: +49-30-4504-3942 (E.G.); +34-91-196-4539 (W.J.J.M.)
| | - Wilfried J. J. Meijer
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Instituto de Biología Molecular Eladio Viñuela (CSIC), C. Nicolás Cabrera 1, Universidad Autónoma, Canto Blanco, 28049 Madrid, Spain;
- Correspondence: (E.G.); (W.J.J.M.); Tel.: +49-30-4504-3942 (E.G.); +34-91-196-4539 (W.J.J.M.)
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7
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Abstract
Despite their ubiquitous nature, few antisense RNAs have been functionally characterized, and this class of RNAs is considered by some to be transcriptional noise. Here, we report that an antisense RNA (asRNA), aMEF (antisense mazEF), functions as a dual regulator for the type II toxin-antitoxin (TA) system mazEF. Unlike type I TA systems and many other regulatory asRNAs, aMEF stimulates the synthesis and translation of mazEF rather than inhibition and degradation. Our data indicate that a double-stranded RNA intermediate and RNase III are not necessary for aMEF-dependent regulation of mazEF expression. The lack of conservation of asRNA promoters has been used to support the hypothesis that asRNAs are spurious transcriptional noise and nonfunctional. We demonstrate that the aMEF promoter is active and functional in Escherichia coli despite poor sequence conservation, indicating that the lack of promoter sequence conservation should not be correlated with functionality. IMPORTANCE Next-generation RNA sequencing of numerous organisms has revealed that transcription is widespread across the genome, termed pervasive transcription, and does not adhere to annotated gene boundaries. The function of pervasive transcription is enigmatic and has generated considerable controversy as to whether it is transcriptional noise or biologically relevant. Antisense transcription is one class of pervasive transcription that occurs from the DNA strand opposite an annotated gene. Relatively few pervasively transcribed asRNAs have been functionally characterized, and their regulatory roles or lack thereof remains unknown. It is important to study examples of these asRNAs and determine if they are functional regulators. In this study, we elucidate the function of an asRNA (aMEF) demonstrating that pervasive transcripts can be functional.
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8
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Defective transcription elongation in human cancers imposes targetable proteotoxic vulnerability. Transl Oncol 2021; 16:101323. [PMID: 34954455 PMCID: PMC8718660 DOI: 10.1016/j.tranon.2021.101323] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 11/12/2021] [Accepted: 12/19/2021] [Indexed: 11/24/2022] Open
Abstract
Successful cancer therapy is contingent on identifying cancer-specific aberrant phenotypes and their associated vulnerabilities. We recently reported that a subset of almost every cancer type contains a genome-wide defect in RNA Polymerase II-mediated transcription elongation (TEdef), which impairs the expression of long genes and confers resistance to anti-tumor immune attack. Using a combination of computational analysis and laboratory experiments, we report that tumor cells with TEdef have widespread overexpression of the components of the protein homeostasis machinery (mostly composed of short genes), including protein folding and clearance. Accordingly, TEdef cells were characterized by abnormally high levels of insoluble protein aggregates in the cytoplasm and autophagy influx. We present evidence that TEdef cells exhibit impaired clearance of misfolded protein aggregates through the ubiquitin-proteasome system, and thus rely on autophagy for their degradation. As such, while these cells were highly resistant to proteasome inhibitors, they were acutely sensitive to inhibitors of autophagy in vitro and in vivo. This study reveals a major aberrant phenotype that is observed in ∼15-25% of all cancers and characterizes a unique cellular vulnerability that can be readily exploited in the clinic to improve treatment efficacy.
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9
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Ruiz-Cantos M, Hutchison CE, Shoulders CC. Musings from the Tribbles Research and Innovation Network. Cancers (Basel) 2021; 13:cancers13184517. [PMID: 34572744 PMCID: PMC8467127 DOI: 10.3390/cancers13184517] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2021] [Revised: 09/02/2021] [Accepted: 09/04/2021] [Indexed: 11/16/2022] Open
Abstract
This commentary integrates historical and modern findings that underpin our understanding of the cell-specific functions of the Tribbles (TRIB) proteins that bear on tumorigenesis. We touch on the initial discovery of roles played by mammalian TRIB proteins in a diverse range of cell-types and pathologies, for example, TRIB1 in regulatory T-cells, TRIB2 in acute myeloid leukaemia and TRIB3 in gliomas; the origins and diversity of TRIB1 transcripts; microRNA-mediated (miRNA) regulation of TRIB1 transcript decay and translation; the substantial conformational changes that ensue on binding of TRIB1 to the transcription factor C/EBPα; and the unique pocket formed by TRIB1 to sequester its C-terminal motif bearing a binding site for the E3 ubiquitin ligase COP1. Unashamedly, the narrative is relayed through the perspective of the Tribbles Research and Innovation Network, and its establishment, progress and future ambitions: the growth of TRIB and COP1 research to hasten discovery of their cell-specific contributions to health and obesity-related cancers.
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10
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Bouvier D, Ferrand J, Chevallier O, Paulsen MT, Ljungman M, Polo SE. Dissecting regulatory pathways for transcription recovery following DNA damage reveals a non-canonical function of the histone chaperone HIRA. Nat Commun 2021; 12:3835. [PMID: 34158510 PMCID: PMC8219801 DOI: 10.1038/s41467-021-24153-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Accepted: 06/03/2021] [Indexed: 12/14/2022] Open
Abstract
Transcription restart after a genotoxic challenge is a fundamental yet poorly understood process. Here, we dissect the interplay between transcription and chromatin restoration after DNA damage by focusing on the human histone chaperone complex HIRA, which is required for transcription recovery post UV. We demonstrate that HIRA is recruited to UV-damaged chromatin via the ubiquitin-dependent segregase VCP to deposit new H3.3 histones. However, this local activity of HIRA is dispensable for transcription recovery. Instead, we reveal a genome-wide function of HIRA in transcription restart that is independent of new H3.3 and not restricted to UV-damaged loci. HIRA coordinates with ASF1B to control transcription restart by two independent pathways: by stabilising the associated subunit UBN2 and by reducing the expression of the transcription repressor ATF3. Thus, HIRA primes UV-damaged chromatin for transcription restart at least in part by relieving transcription inhibition rather than by depositing new H3.3 as an activating bookmark.
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Affiliation(s)
- Déborah Bouvier
- Epigenetics & Cell Fate Centre, UMR7216 CNRS, Université de Paris, Paris, France
| | - Juliette Ferrand
- Epigenetics & Cell Fate Centre, UMR7216 CNRS, Université de Paris, Paris, France
| | - Odile Chevallier
- Epigenetics & Cell Fate Centre, UMR7216 CNRS, Université de Paris, Paris, France
| | - Michelle T Paulsen
- Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, USA
| | - Mats Ljungman
- Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, USA
| | - Sophie E Polo
- Epigenetics & Cell Fate Centre, UMR7216 CNRS, Université de Paris, Paris, France.
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11
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Miguel-Arribas A, Val-Calvo J, Gago-Córdoba C, Izquierdo JM, Abia D, Wu LJ, Errington J, Meijer WJJ. A novel bipartite antitermination system widespread in conjugative elements of Gram-positive bacteria. Nucleic Acids Res 2021; 49:5553-5567. [PMID: 33999173 PMCID: PMC8191782 DOI: 10.1093/nar/gkab360] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 04/09/2021] [Accepted: 04/23/2021] [Indexed: 11/18/2022] Open
Abstract
Transcriptional regulation allows adaptive and coordinated gene expression, and is essential for life. Processive antitermination systems alter the transcription elongation complex to allow the RNA polymerase to read through multiple terminators in an operon. Here, we describe the discovery of a novel bipartite antitermination system that is widespread among conjugative elements from Gram-positive bacteria, which we named conAn. This system is composed of a large RNA element that exerts antitermination, and a protein that functions as a processivity factor. Besides allowing coordinated expression of very long operons, we show that these systems allow differential expression of genes within an operon, and probably contribute to strict regulation of the conjugation genes by minimizing the effects of spurious transcription. Mechanistic features of the conAn system are likely to decisively influence its host range, with important implications for the spread of antibiotic resistance and virulence genes.
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Affiliation(s)
- Andrés Miguel-Arribas
- Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM), C. Nicolás Cabrera 1, Universidad Autónoma de Madrid, Canto Blanco, 28049 Madrid, Spain
| | - Jorge Val-Calvo
- Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM), C. Nicolás Cabrera 1, Universidad Autónoma de Madrid, Canto Blanco, 28049 Madrid, Spain
| | - César Gago-Córdoba
- Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM), C. Nicolás Cabrera 1, Universidad Autónoma de Madrid, Canto Blanco, 28049 Madrid, Spain
| | - José M Izquierdo
- Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM), C. Nicolás Cabrera 1, Universidad Autónoma de Madrid, Canto Blanco, 28049 Madrid, Spain
| | - David Abia
- Bioinformatics Facility, Centro de Biología Molecular "Severo Ochoa", (CSIC-UAM), C. Nicolás Cabrera 1, Universidad Autónoma de Madrid, Canto Blanco, 28049 Madrid, Spain
| | - Ling Juan Wu
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Richardson Road, Newcastle Upon Tyne, NE2 4AX, UK
| | - Jeff Errington
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Richardson Road, Newcastle Upon Tyne, NE2 4AX, UK
| | - Wilfried J J Meijer
- Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM), C. Nicolás Cabrera 1, Universidad Autónoma de Madrid, Canto Blanco, 28049 Madrid, Spain
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12
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McCauley BS, Dang W. Loosening chromatin and dysregulated transcription: a perspective on cryptic transcription during mammalian aging. Brief Funct Genomics 2021; 21:56-61. [PMID: 34050364 DOI: 10.1093/bfgp/elab026] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 04/23/2021] [Accepted: 04/27/2021] [Indexed: 12/14/2022] Open
Abstract
Cryptic transcription, the initiation of transcription from non-promoter regions within a gene body, is a type of transcriptional dysregulation that occurs throughout eukaryotes. In mammals, cryptic transcription is normally repressed at the level of chromatin, and this process is increased upon perturbation of complexes that increase intragenic histone H3 lysine 4 methylation or decrease intragenic H3 lysine 36 methylation, DNA methylation, or nucleosome occupancy. Significantly, similar changes to chromatin structure occur during aging, and, indeed, recent work indicates that cryptic transcription is elevated during aging in mammalian stem cells. Although increased cryptic transcription is known to promote aging in yeast, whether elevated cryptic transcription also contributes to mammalian aging is unclear. There is ample evidence that perturbations known to increase cryptic transcription are deleterious in embryonic and adult stem cells, and in some cases phenocopy certain aging phenotypes. Furthermore, an increase in cryptic transcription requires or impedes pathways that are known to have reduced function during aging, potentially exacerbating other aging phenotypes. Thus, we propose that increased cryptic transcription contributes to mammalian stem cell aging.
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13
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Matteau D, Lachance J, Grenier F, Gauthier S, Daubenspeck JM, Dybvig K, Garneau D, Knight TF, Jacques P, Rodrigue S. Integrative characterization of the near-minimal bacterium Mesoplasma florum. Mol Syst Biol 2020; 16:e9844. [PMID: 33331123 PMCID: PMC7745072 DOI: 10.15252/msb.20209844] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 11/02/2020] [Accepted: 11/03/2020] [Indexed: 12/11/2022] Open
Abstract
The near-minimal bacterium Mesoplasma florum is an interesting model for synthetic genomics and systems biology due to its small genome (~ 800 kb), fast growth rate, and lack of pathogenic potential. However, fundamental aspects of its biology remain largely unexplored. Here, we report a broad yet remarkably detailed characterization of M. florum by combining a wide variety of experimental approaches. We investigated several physical and physiological parameters of this bacterium, including cell size, growth kinetics, and biomass composition of the cell. We also performed the first genome-wide analysis of its transcriptome and proteome, notably revealing a conserved promoter motif, the organization of transcription units, and the transcription and protein expression levels of all protein-coding sequences. We converted gene transcription and expression levels into absolute molecular abundances using biomass quantification results, generating an unprecedented view of the M. florum cellular composition and functions. These characterization efforts provide a strong experimental foundation for the development of a genome-scale model for M. florum and will guide future genome engineering endeavors in this simple organism.
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Affiliation(s)
- Dominick Matteau
- Département de biologieUniversité de SherbrookeSherbrookeQCCanada
| | | | - Frédéric Grenier
- Département de biologieUniversité de SherbrookeSherbrookeQCCanada
| | - Samuel Gauthier
- Département de biologieUniversité de SherbrookeSherbrookeQCCanada
| | | | - Kevin Dybvig
- Department of GeneticsUniversity of Alabama at BirminghamBirminghamALUSA
| | - Daniel Garneau
- Département de biologieUniversité de SherbrookeSherbrookeQCCanada
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14
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Mejía-Almonte C, Busby SJW, Wade JT, van Helden J, Arkin AP, Stormo GD, Eilbeck K, Palsson BO, Galagan JE, Collado-Vides J. Redefining fundamental concepts of transcription initiation in bacteria. Nat Rev Genet 2020; 21:699-714. [PMID: 32665585 PMCID: PMC7990032 DOI: 10.1038/s41576-020-0254-8] [Citation(s) in RCA: 77] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/29/2020] [Indexed: 12/15/2022]
Abstract
Despite enormous progress in understanding the fundamentals of bacterial gene regulation, our knowledge remains limited when compared with the number of bacterial genomes and regulatory systems to be discovered. Derived from a small number of initial studies, classic definitions for concepts of gene regulation have evolved as the number of characterized promoters has increased. Together with discoveries made using new technologies, this knowledge has led to revised generalizations and principles. In this Expert Recommendation, we suggest precise, updated definitions that support a logical, consistent conceptual framework of bacterial gene regulation, focusing on transcription initiation. The resulting concepts can be formalized by ontologies for computational modelling, laying the foundation for improved bioinformatics tools, knowledge-based resources and scientific communication. Thus, this work will help researchers construct better predictive models, with different formalisms, that will be useful in engineering, synthetic biology, microbiology and genetics.
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Affiliation(s)
- Citlalli Mejía-Almonte
- Programa de Genómica Computacional, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Morelos, Cuernavaca, México
| | | | - Joseph T Wade
- Division of Genetics, Wadsworth Center, New York State Department of Health, Albany, NY, USA
| | - Jacques van Helden
- Aix-Marseille University, INSERM UMR S 1090, Theory and Approaches of Genome Complexity (TAGC), Marseille, France
- CNRS, Institut Français de Bioinformatique, IFB-core, UMS 3601, Evry, France
| | - Adam P Arkin
- Department of Bioengineering, University of California, Berkeley, Berkeley, CA, USA
| | - Gary D Stormo
- Department of Genetics, Washington University School of Medicine, St Louis, MO, USA
| | - Karen Eilbeck
- Department of Biomedical Informatics, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Bernhard O Palsson
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA
| | - James E Galagan
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Julio Collado-Vides
- Programa de Genómica Computacional, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Morelos, Cuernavaca, México.
- Department of Biomedical Engineering, Boston University, Boston, MA, USA.
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15
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The PWWP2A Histone Deacetylase Complex Represses Intragenic Spurious Transcription Initiation in mESCs. iScience 2020; 23:101741. [PMID: 33235983 PMCID: PMC7670215 DOI: 10.1016/j.isci.2020.101741] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 09/22/2020] [Accepted: 10/23/2020] [Indexed: 12/26/2022] Open
Abstract
Transcriptional fidelity depends on accurate promoter selection and initiation from the correct sites. In yeast, H3K36me3-mediated recruitment of the Rpd3S HDAC complex to gene bodies suppresses spurious transcription initiation. Here we describe an equivalent pathway in metazoans. PWWP2A/B is an H3K36me3 reader that forms a stable complex with HDAC1/2. We used CAGE-seq to profile all transcription initiation sites in wild-type mESCs and cells lacking PWWP2A/B. Loss of PWWP2A/B enhances spurious initiation from intragenic sites present in wild-type mESCs, and this effect is associated with increased levels of initiating Pol-II and histone acetylation. Spurious initiation events in Pwwp2a/b DKO mESCs do not overlap in genomic location or chromatin features with spurious sites that arise in Dnmt3b KO mESCs, previously reported to function in the suppression of intragenic transcriptional initiation, suggesting these pathways function cooperatively in maintaining the fidelity of transcription initiation in metazoans. Loss of PWWP2A/B leads to increased levels of spurious transcription initiation Spurious TSS sites are predominantly in the gene bodies of highly expressed genes Spurious sites are marked with increased histone acetylation and initiating Pol II PWWP2-spurious TSSs are distinct from those caused by DNMT3B loss
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16
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Gallegos JE, Kar DM, Ray I, Ray I, Peccoud J. Securing the Exchange of Synthetic Genetic Constructs Using Digital Signatures. ACS Synth Biol 2020; 9:2656-2664. [PMID: 32916048 DOI: 10.1021/acssynbio.0c00401] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The field of synthetic biology relies on an ever-growing supply chain of synthetic genetic material. Technologies to secure the exchange of this material are still in their infancy. Solutions proposed thus far have focused on watermarks, a dated security approach that can be used to claim authorship, but is subject to counterfeit, and does not provide any information about the integrity of the genetic material itself. In this manuscript, we describe how data encryption and digital signature algorithms can be used to ensure the integrity and authenticity of synthetic genetic constructs. Using a pilot software that generates digital signatures and other encrypted data for plasmids, we demonstrate that we can predictably extract information about the author, the identity, the integrity of plasmid sequences, and even annotations from sequencing data alone without a reference sequence, all without compromising the function of the plasmids. Encoding a digital signature into a DNA molecule provides an avenue for genetic designers to claim authorship of DNA molecules. This technology could help compliance with material transfer agreements and other licensing agreements.
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Affiliation(s)
- Jenna E. Gallegos
- Colorado State University, Chemical and Biological Engineering, 1370 Campus Delivery, Fort Collins, Colorado 80523, United States
| | - Diptendu M. Kar
- Colorado State University, Computer Sciences, 1873 Campus Delivery, Fort Collins, Colorado 80523, United States
| | - Indrakshi Ray
- Colorado State University, Computer Sciences, 1873 Campus Delivery, Fort Collins, Colorado 80523, United States
| | - Indrajit Ray
- Colorado State University, Computer Sciences, 1873 Campus Delivery, Fort Collins, Colorado 80523, United States
| | - Jean Peccoud
- Colorado State University, Chemical and Biological Engineering, 1370 Campus Delivery, Fort Collins, Colorado 80523, United States
- GenoFAB, Inc., 2580 E. Harmony Road, Ste 201, Fort Collins, Colorado 80528, United States
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17
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Whitworth DE, Swain MT. A survey of non-coding RNAs in the social and predatory myxobacterium Myxococcus xanthus DK1622. Mol Omics 2020; 16:492-502. [PMID: 32780046 DOI: 10.1039/d0mo00068j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Prokaryotic ncRNAs are important regulators of gene expression, and can be involved in complex signalling networks. The myxobacteria are model organisms for studies into multicellular development and microbial predation, being particularly renowned for their large genomes and exceptionally sophisticated signalling networks. However, apart from two specific examples, little is known about their regulatory ncRNAs. Here, we integrate bioinformatic predictions and transcriptome sequence data to provide a comprehensive survey of the ncRNAs made by the exemplar myxobacterium M. xanthus DK1622. M. xanthus RNA-seq data from four experimental conditions was interrogated to identify transcripts mapping outside coding sequences and to known ncRNAs. The resulting 37 ncRNAs were clustered on the genome and most (30/37) were conserved across the myxobacteria. A majority of ncRNAs (22/37) were intergenic, while 13 were at least partially antisense to protein-coding genes. Predicted promoter and terminator sequences explained the start/stop sites of 18 ncRNAs. mRNA targets for the ncRNAs were predicted, including plausible candidates for a known regulatory ncRNA. 22 ncRNAs were differentially expressed by nutrient availability and expression of 25 predicted targets was found to correlate strongly with that of their regulatory ncRNAs. Sharing of predicted mRNA targets by multiple ncRNAs suggests that some ncRNAs might regulate each other within signalling networks. This genomic survey of M. xanthus ncRNA biology provides a starting point for further studies of myxobacterial ncRNAs, which are likely to have important functions in these industrially important and sophisticated organisms.
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Affiliation(s)
- David E Whitworth
- Institute of Biological Environmental and Rural Sciences, Aberystwyth University, SY23 3DD, UK.
| | - Martin T Swain
- Institute of Biological Environmental and Rural Sciences, Aberystwyth University, SY23 3DD, UK.
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18
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Armstrong MJ, Jin Y, Allen EG, Jin P. Diverse and dynamic DNA modifications in brain and diseases. Hum Mol Genet 2020; 28:R241-R253. [PMID: 31348493 DOI: 10.1093/hmg/ddz179] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 07/17/2019] [Accepted: 07/18/2019] [Indexed: 12/17/2022] Open
Abstract
DNA methylation is a class of epigenetic modification essential for coordinating gene expression timing and magnitude throughout normal brain development and for proper brain function following development. Aberrant methylation changes are associated with changes in chromatin architecture, transcriptional alterations and a host of neurological disorders and diseases. This review highlights recent advances in our understanding of the methylome's functionality and covers potential new roles for DNA methylation, their readers, writers, and erasers. Additionally, we examine novel insights into the relationship between the methylome, DNA-protein interactions, and their contribution to neurodegenerative diseases. Lastly, we outline the gaps in our knowledge that will likely be filled through the widespread use of newer technologies that provide greater resolution into how individual cell types are affected by disease and the contribution of each individual modification site to disease pathogenicity.
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Affiliation(s)
- Matthew J Armstrong
- Department of Human Genetics, School of Medicine, Emory University, Atlanta, GA, USA
| | - Yulin Jin
- Department of Human Genetics, School of Medicine, Emory University, Atlanta, GA, USA
| | - Emily G Allen
- Department of Human Genetics, School of Medicine, Emory University, Atlanta, GA, USA
| | - Peng Jin
- Department of Human Genetics, School of Medicine, Emory University, Atlanta, GA, USA
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19
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AL-Eitan LN, Alghamdi MA, Tarkhan AH, Al-Qarqaz FA. Genome-Wide Tiling Array Analysis of HPV-Induced Warts Reveals Aberrant Methylation of Protein-Coding and Non-Coding Regions. Genes (Basel) 2019; 11:E34. [PMID: 31892232 PMCID: PMC7017144 DOI: 10.3390/genes11010034] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 12/18/2019] [Accepted: 12/22/2019] [Indexed: 12/18/2022] Open
Abstract
The human papillomaviruses (HPV) are a group of double-stranded DNA viruses that exhibit an exclusive tropism for squamous epithelia. HPV can either be low- or high-risk depending on its ability to cause benign lesions or cancer, respectively. Unsurprisingly, the majority of epigenetic research has focused on the high-risk HPV types, neglecting the low-risk types in the process. Therefore, the main objective of this study is to better understand the epigenetics of wart formation by investigating the differences in methylation between HPV-induced cutaneous warts and normal skin. A number of clear and very significant differences in methylation patterns were found between cutaneous warts and normal skin. Around 55% of the top-ranking 100 differentially methylated genes in warts were protein coding, including the EXOC4, KCNU, RTN1, LGI1, IRF2, and NRG1 genes. Additionally, non-coding RNA genes, such as the AZIN1-AS1, LINC02008, and MGC27382 genes, constituted 11% of the top-ranking 100 differentially methylated genes. Warts exhibited a unique pattern of methylation that is a possible explanation for their transient nature. Since the genetics of cutaneous wart formation are not completely known, the findings of the present study could contribute to a better understanding of how HPV infection modulates host methylation to give rise to warts in the skin.
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Affiliation(s)
- Laith N. AL-Eitan
- Department of Applied Biological Sciences, Jordan University of Science and Technology, Irbid 22110, Jordan;
- Department of Biotechnology and Genetic Engineering, Jordan University of Science and Technology, Irbid 22110, Jordan
| | - Mansour A. Alghamdi
- Department of Anatomy, College of Medicine, King Khalid University, Abha 61421, Saudi Arabia;
| | - Amneh H. Tarkhan
- Department of Applied Biological Sciences, Jordan University of Science and Technology, Irbid 22110, Jordan;
| | - Firas A. Al-Qarqaz
- Department of Internal Medicine, Jordan University of Science and Technology, Irbid 22110, Jordan;
- Division of Dermatology, Department of Internal Medicine, King Abdullah University Hospital, Jordan University of Science and Technology, Irbid 22110, Jordan
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20
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Chang HW, Nizovtseva EV, Razin SV, Formosa T, Gurova KV, Studitsky VM. Histone Chaperone FACT and Curaxins: Effects on Genome Structure and Function. ACTA ACUST UNITED AC 2019; 5. [PMID: 31853507 DOI: 10.20517/2394-4722.2019.31] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The histone chaperone FACT plays important roles in essentially every chromatin-associated process and is an important indirect target of the curaxin class of anti-cancer drugs. Curaxins are aromatiс compounds that intercalate into DNA and can trap FACT in bulk chromatin, thus interfering with its distribution and its functions in cancer cells. Recent studies have provided mechanistic insight into how FACT and curaxins cooperate to promote unfolding of nucleosomes and chromatin fibers, resulting in genome-wide disruption of contact chromatin domain boundaries, perturbation of higher order chromatin organization, and global disregulation of gene expression. Here, we discuss the implications of these insights for cancer biology.
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Affiliation(s)
- Han-Wen Chang
- Cancer Epigenetics Program, Fox Chase Cancer Center, 333 Cottman Ave., Philadelphia, PA 19422, USA
| | - Ekaterina V Nizovtseva
- Cancer Epigenetics Program, Fox Chase Cancer Center, 333 Cottman Ave., Philadelphia, PA 19422, USA
| | - Sergey V Razin
- Institute of Gene Biology RAS, 34/5 Vavilov Str., 119334 Moscow, Russia.,Biology Faculty, Lomonosov Moscow State University, 1 Leninskie Gory, 119992 Moscow, Russia
| | - Tim Formosa
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah 84132, USA
| | - Katerina V Gurova
- Department of Cell Stress Biology, Roswell Park Cancer Institute, Elm and Carlton St, Buffalo, NY14263, USA
| | - Vasily M Studitsky
- Cancer Epigenetics Program, Fox Chase Cancer Center, 333 Cottman Ave., Philadelphia, PA 19422, USA.,Biology Faculty, Lomonosov Moscow State University, 1 Leninskie Gory, 119992 Moscow, Russia
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21
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Magán A, Amman F, El-Isa F, Hartl N, Shamovsky I, Nudler E, Schroeder R, Sedlyarova N. iRAPs curb antisense transcription in E. coli. Nucleic Acids Res 2019; 47:10894-10905. [PMID: 31535128 PMCID: PMC6847712 DOI: 10.1093/nar/gkz791] [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: 05/09/2019] [Revised: 09/03/2019] [Accepted: 09/09/2019] [Indexed: 01/27/2023] Open
Abstract
RNA polymerase-binding RNA aptamers (RAPs) are natural RNA elements that control transcription in cis by directly contacting RNA polymerase. Many RAPs inhibit transcription by inducing Rho-dependent termination in Escherichia coli. Here, we studied the role of inhibitory RAPs (iRAPs) in modulation of antisense transcription (AT) using in silico and in vivo approaches. We revisited the antisense transcriptome in cells with impaired AT regulators (Rho, H-NS and RNaseIII) and searched for the presence of RAPs within antisense RNAs. Many of these RAPs were found at key genomic positions where they terminate AT. By exploring the activity of several RAPs both in a reporter system and in their natural genomic context, we confirmed their significant role in AT regulation. RAPs coordinate Rho activity at the antisense strand and terminate antisense transcripts. In some cases, they stimulated sense expression by alleviating ongoing transcriptional interference. Essentially, our data postulate RAPs as key determinants of Rho-mediated AT regulation in E. coli.
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Affiliation(s)
- Andrés Magán
- Department of Biochemistry and Cell biology, Max F. Perutz Laboratories, University of Vienna, Vienna 1030, Austria
| | - Fabian Amman
- Department of Biochemistry and Cell biology, Max F. Perutz Laboratories, University of Vienna, Vienna 1030, Austria
- Institute for Theoretical Chemistry, University of Vienna, Vienna 1090, Austria
- Department of Cell and Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Vienna 1090, Austria
| | - Fatinah El-Isa
- Department of Biochemistry and Cell biology, Max F. Perutz Laboratories, University of Vienna, Vienna 1030, Austria
| | - Natascha Hartl
- Department of Biochemistry and Cell biology, Max F. Perutz Laboratories, University of Vienna, Vienna 1030, Austria
| | - Ilya Shamovsky
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA
| | - Evgeny Nudler
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA
- Howard Hughes Medical Institute, New York University School of Medicine, New York, NY 10016, USA
| | - Renée Schroeder
- Department of Biochemistry and Cell biology, Max F. Perutz Laboratories, University of Vienna, Vienna 1030, Austria
| | - Nadezda Sedlyarova
- Department of Biochemistry and Cell biology, Max F. Perutz Laboratories, University of Vienna, Vienna 1030, Austria
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22
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Scandaglia M, Barco A. Contribution of spurious transcription to intellectual disability disorders. J Med Genet 2019; 56:491-498. [PMID: 30745423 DOI: 10.1136/jmedgenet-2018-105668] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 12/17/2018] [Accepted: 01/18/2019] [Indexed: 12/31/2022]
Abstract
During the development of multicellular organisms, chromatin-modifying enzymes orchestrate the establishment of gene expression programmes that characterise each differentiated cell type. These enzymes also contribute to the maintenance of cell type-specific transcription profiles throughout life. But what happens when epigenomic regulation goes awry? Genomic screens in experimental models of intellectual disability disorders (IDDs) caused by mutations in epigenetic machinery-encoding genes have shown that transcriptional dysregulation constitutes a hallmark of these conditions. Here, we underscore the connections between a subset of chromatin-linked IDDs and spurious transcription in brain cells. We also propose that aberrant gene expression in neurons, including both the ectopic transcription of non-neuronal genes and the activation of cryptic promoters, may importantly contribute to the pathoaetiology of these disorders.
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Affiliation(s)
- Marilyn Scandaglia
- Molecular Neurobiology and Neuropathology Unit, Instituto de Neurociencias (UMH-CSIC), San Juan de Alicante, Alicante, Spain
| | - Angel Barco
- Molecular Neurobiology and Neuropathology Unit, Instituto de Neurociencias (UMH-CSIC), San Juan de Alicante, Alicante, Spain
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23
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Kapshikar RM, Gowrishankar J. Direct inhibition of transcription in vitro by the isolated N-terminal domain of the Escherichia coli nucleoid-associated protein H-NS and by its paralogue Hha. MICROBIOLOGY-SGM 2019; 165:463-474. [PMID: 30724731 DOI: 10.1099/mic.0.000780] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
H-NS is an abundant nucleoid-associated protein in the enterobacteria that mediates both chromatin compaction and transcriptional silencing of numerous genes, especially those that have been acquired by horizontal transfer or that are involved in virulence functions. With two dimerization domains (N-terminal and central) and a C-terminal DNA-binding domain, the 15 kDa H-NS polypeptide can assemble as long polymeric filaments on DNA, and mutations in any of the three domains confer a dominant-negative phenotype in vivo by a subunit-poisoning mechanism. Here we confirm that several of these mutants [L26P, I119T and a truncation beyond residue 92(Δ93)] are also dominant-negative in vitro, in that they reverse the inhibition imposed by native H-NS in two different transcription assay formats (initiation+elongation, or elongation alone). On the other hand, another dominant-negative truncation mutant Δ64 (which possesses only the protein's N-terminal domain) per se completely and unexpectedly inhibited transcription in both assay formats. The Hha protein, which is a paralogue of H-NS and resembles its isolated N-terminal domain, also behaved like Δ64 as an inhibitor of transcription in vitro. We propose that under certain growth conditions, Escherichia coli RNA polymerase may be the direct inhibitory target of Hha, and that this effect is experimentally mimicked by the isolated N-terminal domain of H-NS.
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Affiliation(s)
- Rajvardhan M Kapshikar
- 1Laboratory of Bacterial Genetics, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, India.,2Graduate Studies, Manipal Academy of Higher Education, Manipal, India
| | - J Gowrishankar
- 1Laboratory of Bacterial Genetics, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, India
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24
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Patange O, Schwall C, Jones M, Villava C, Griffith DA, Phillips A, Locke JCW. Escherichia coli can survive stress by noisy growth modulation. Nat Commun 2018; 9:5333. [PMID: 30559445 PMCID: PMC6297224 DOI: 10.1038/s41467-018-07702-z] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 11/13/2018] [Indexed: 12/31/2022] Open
Abstract
Gene expression can be noisy, as can the growth of single cells. Such cell-to-cell variation has been implicated in survival strategies for bacterial populations. However, it remains unclear how single cells couple gene expression with growth to implement these strategies. Here, we show how noisy expression of a key stress-response regulator, RpoS, allows E. coli to modulate its growth dynamics to survive future adverse environments. We reveal a dynamic positive feedback loop between RpoS and growth rate that produces multi-generation RpoS pulses. We do so experimentally using single-cell, time-lapse microscopy and microfluidics and theoretically with a stochastic model. Next, we demonstrate that E. coli prepares for sudden stress by entering prolonged periods of slow growth mediated by RpoS. This dynamic phenotype is captured by the RpoS-growth feedback model. Our synthesis of noisy gene expression, growth, and survival paves the way for further exploration of functional phenotypic variability. Noisy gene expression leading to phenotypic variability can help organisms to survive in changing environments. Here, Patange et al. show that noisy expression of a stress response regulator, RpoS, allows E. coli cells to modulate their growth rates to survive future adverse environments.
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Affiliation(s)
- Om Patange
- Sainsbury Laboratory, University of Cambridge, Cambridge, CB2 1LR, UK.,Department of Biochemistry, University of Cambridge, Cambridge, CB2 1QW, UK
| | - Christian Schwall
- Sainsbury Laboratory, University of Cambridge, Cambridge, CB2 1LR, UK.,Department of Biochemistry, University of Cambridge, Cambridge, CB2 1QW, UK
| | - Matt Jones
- Sainsbury Laboratory, University of Cambridge, Cambridge, CB2 1LR, UK
| | - Casandra Villava
- Sainsbury Laboratory, University of Cambridge, Cambridge, CB2 1LR, UK
| | | | | | - James C W Locke
- Sainsbury Laboratory, University of Cambridge, Cambridge, CB2 1LR, UK. .,Department of Biochemistry, University of Cambridge, Cambridge, CB2 1QW, UK. .,Microsoft Research, Cambridge, CB1 2FB, UK.
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25
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Exaptation at the molecular genetic level. SCIENCE CHINA-LIFE SCIENCES 2018; 62:437-452. [PMID: 30798493 DOI: 10.1007/s11427-018-9447-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2018] [Accepted: 12/01/2018] [Indexed: 12/22/2022]
Abstract
The realization that body parts of animals and plants can be recruited or coopted for novel functions dates back to, or even predates the observations of Darwin. S.J. Gould and E.S. Vrba recognized a mode of evolution of characters that differs from adaptation. The umbrella term aptation was supplemented with the concept of exaptation. Unlike adaptations, which are restricted to features built by selection for their current role, exaptations are features that currently enhance fitness, even though their present role was not a result of natural selection. Exaptations can also arise from nonaptations; these are characters which had previously been evolving neutrally. All nonaptations are potential exaptations. The concept of exaptation was expanded to the molecular genetic level which aided greatly in understanding the enormous potential of neutrally evolving repetitive DNA-including transposed elements, formerly considered junk DNA-for the evolution of genes and genomes. The distinction between adaptations and exaptations is outlined in this review and examples are given. Also elaborated on is the fact that such distinctions are sometimes more difficult to determine; this is a widespread phenomenon in biology, where continua abound and clear borders between states and definitions are rare.
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26
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Cheah HL, Raabe CA, Lee LP, Rozhdestvensky TS, Citartan M, Ahmed SA, Tang TH. Bacterial regulatory RNAs: complexity, function, and putative drug targeting. Crit Rev Biochem Mol Biol 2018; 53:335-355. [PMID: 29793351 DOI: 10.1080/10409238.2018.1473330] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Over the past decade, RNA-deep sequencing has uncovered copious non-protein coding RNAs (npcRNAs) in bacteria. Many of them are key players in the regulation of gene expression, taking part in various regulatory circuits, such as metabolic responses to different environmental stresses, virulence, antibiotic resistance, and host-pathogen interactions. This has contributed to the high adaptability of bacteria to changing or even hostile environments. Their mechanisms include the regulation of transcriptional termination, modulation of translation, and alteration of messenger RNA (mRNA) stability, as well as protein sequestration. Here, the mechanisms of gene expression by regulatory bacterial npcRNAs are comprehensively reviewed and supplemented with well-characterized examples. This class of molecules and their mechanisms of action might be useful targets for the development of novel antibiotics.
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Affiliation(s)
- Hong-Leong Cheah
- a Advanced Medical & Dental Institute (AMDI), Universiti Sains Malaysia , Kepala Batas , Malaysia
| | - Carsten A Raabe
- b Institute of Experimental Pathology, Centre for Molecular Biology of Inflammation , University of Münster , Münster , Germany.,c Brandenburg Medical School (MHB) , Neuruppin , Germany.,d Institute of Medical Biochemistry, Centre for Molecular Biology of Inflammation , University of Münster , Münster , Germany
| | - Li-Pin Lee
- a Advanced Medical & Dental Institute (AMDI), Universiti Sains Malaysia , Kepala Batas , Malaysia
| | - Timofey S Rozhdestvensky
- e Medical Faculty, Transgenic Mouse and Genome Engineering Model Core Facility (TRAM) , University of Münster , Münster , Germany
| | - Marimuthu Citartan
- a Advanced Medical & Dental Institute (AMDI), Universiti Sains Malaysia , Kepala Batas , Malaysia
| | - Siti Aminah Ahmed
- a Advanced Medical & Dental Institute (AMDI), Universiti Sains Malaysia , Kepala Batas , Malaysia
| | - Thean-Hock Tang
- a Advanced Medical & Dental Institute (AMDI), Universiti Sains Malaysia , Kepala Batas , Malaysia
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27
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Raghunathan N, Kapshikar RM, Leela JK, Mallikarjun J, Bouloc P, Gowrishankar J. Genome-wide relationship between R-loop formation and antisense transcription in Escherichia coli. Nucleic Acids Res 2018; 46:3400-3411. [PMID: 29474582 PMCID: PMC5909445 DOI: 10.1093/nar/gky118] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Revised: 01/30/2018] [Accepted: 02/09/2018] [Indexed: 12/22/2022] Open
Abstract
Transcription termination by Rho is essential for viability in various bacteria, including some major pathogens. Since Rho acts by targeting nascent RNAs that are not simultaneously translated, it also regulates antisense transcription. Here we show that RNase H-deficient mutants of Escherichia coli exhibit heightened sensitivity to the Rho inhibitor bicyclomycin, and that Rho deficiency provokes increased formation of RNA-DNA hybrids (R-loops) which is ameliorated by expression of the phage T4-derived R-loop helicase UvsW. We also provide evidence that in Rho-deficient cells, R-loop formation blocks subsequent rounds of antisense transcription at more than 500 chromosomal loci. Hence these antisense transcripts, which can extend beyond 10 kb in their length, are only detected when Rho function is absent or compromised and the UvsW helicase is concurrently expressed. Thus the potential for antisense transcription in bacteria is much greater than hitherto recognized; and the cells are able to retain viability even when nearly one-quarter of their total non-rRNA abundance is accounted for by antisense transcripts, provided that R-loop formation from them is curtailed.
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Affiliation(s)
- Nalini Raghunathan
- Laboratory of Bacterial Genetics, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, Telangana 500039, India
- Graduate Studies, Manipal Academy of Higher Education, Manipal, Karnataka 576104, India
| | - Rajvardhan M Kapshikar
- Laboratory of Bacterial Genetics, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, Telangana 500039, India
- Graduate Studies, Manipal Academy of Higher Education, Manipal, Karnataka 576104, India
| | - Jakku K Leela
- Laboratory of Bacterial Genetics, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, Telangana 500039, India
| | - Jillella Mallikarjun
- Laboratory of Bacterial Genetics, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, Telangana 500039, India
- Graduate Studies, Manipal Academy of Higher Education, Manipal, Karnataka 576104, India
| | - Philippe Bouloc
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, F-91198, Gif-sur-Yvette cedex, France
| | - Jayaraman Gowrishankar
- Laboratory of Bacterial Genetics, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, Telangana 500039, India
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