1
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Zhang H, Vandesompele J, Braeckmans K, De Smedt SC, Remaut K. Nucleic acid degradation as barrier to gene delivery: a guide to understand and overcome nuclease activity. Chem Soc Rev 2024; 53:317-360. [PMID: 38073448 DOI: 10.1039/d3cs00194f] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2024]
Abstract
Gene therapy is on its way to revolutionize the treatment of both inherited and acquired diseases, by transferring nucleic acids to correct a disease-causing gene in the target cells of patients. In the fight against infectious diseases, mRNA-based therapeutics have proven to be a viable strategy in the recent Covid-19 pandemic. Although a growing number of gene therapies have been approved, the success rate is limited when compared to the large number of preclinical and clinical trials that have been/are being performed. In this review, we highlight some of the hurdles which gene therapies encounter after administration into the human body, with a focus on nucleic acid degradation by nucleases that are extremely abundant in mammalian organs, biological fluids as well as in subcellular compartments. We overview the available strategies to reduce the biodegradation of gene therapeutics after administration, including chemical modifications of the nucleic acids, encapsulation into vectors and co-administration with nuclease inhibitors and discuss which strategies are applied for clinically approved nucleic acid therapeutics. In the final part, we discuss the currently available methods and techniques to qualify and quantify the integrity of nucleic acids, with their own strengths and limitations.
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Affiliation(s)
- Heyang Zhang
- Laboratory for General Biochemistry and Physical Pharmacy, Department of Pharmaceutical Sciences, Ghent University, 9000 Ghent, Belgium.
- Leiden Academic Centre for Drug Research, Leiden University, 2333 CC Leiden, The Netherlands
| | - Jo Vandesompele
- Department of Biomolecular Medicine, Ghent University, 9000 Ghent, Belgium
- Cancer Research Institute Ghent (CRIG), Ghent, Belgium
| | - Kevin Braeckmans
- Laboratory for General Biochemistry and Physical Pharmacy, Department of Pharmaceutical Sciences, Ghent University, 9000 Ghent, Belgium.
- Centre for Nano- and Biophotonics, Ghent University, 9000 Ghent, Belgium
| | - Stefaan C De Smedt
- Laboratory for General Biochemistry and Physical Pharmacy, Department of Pharmaceutical Sciences, Ghent University, 9000 Ghent, Belgium.
- Cancer Research Institute Ghent (CRIG), Ghent, Belgium
- Centre for Nano- and Biophotonics, Ghent University, 9000 Ghent, Belgium
| | - Katrien Remaut
- Laboratory for General Biochemistry and Physical Pharmacy, Department of Pharmaceutical Sciences, Ghent University, 9000 Ghent, Belgium.
- Cancer Research Institute Ghent (CRIG), Ghent, Belgium
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2
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Wilby EL, Weil TT. Relating the Biogenesis and Function of P Bodies in Drosophila to Human Disease. Genes (Basel) 2023; 14:1675. [PMID: 37761815 PMCID: PMC10530015 DOI: 10.3390/genes14091675] [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: 07/31/2023] [Revised: 08/17/2023] [Accepted: 08/18/2023] [Indexed: 09/29/2023] Open
Abstract
Drosophila has been a premier model organism for over a century and many discoveries in flies have furthered our understanding of human disease. Flies have been successfully applied to many aspects of health-based research spanning from behavioural addiction, to dysplasia, to RNA dysregulation and protein misfolding. Recently, Drosophila tissues have been used to study biomolecular condensates and their role in multicellular systems. Identified in a wide range of plant and animal species, biomolecular condensates are dynamic, non-membrane-bound sub-compartments that have been observed and characterised in the cytoplasm and nuclei of many cell types. Condensate biology has exciting research prospects because of their diverse roles within cells, links to disease, and potential for therapeutics. In this review, we will discuss processing bodies (P bodies), a conserved biomolecular condensate, with a particular interest in how Drosophila can be applied to advance our understanding of condensate biogenesis and their role in disease.
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Affiliation(s)
| | - Timothy T. Weil
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK;
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3
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Kramer S, Karolak NK, Odenwald J, Gabiatti B, Castañeda Londoño P, Zavřelová A, Freire E, Almeida K, Braune S, Moreira C, Eder A, Goos C, Field M, Carrington M, Holetz F, Górna M, Zoltner M. A unique mRNA decapping complex in trypanosomes. Nucleic Acids Res 2023; 51:7520-7540. [PMID: 37309887 PMCID: PMC10415143 DOI: 10.1093/nar/gkad497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 05/18/2023] [Accepted: 06/06/2023] [Indexed: 06/14/2023] Open
Abstract
Removal of the mRNA 5' cap primes transcripts for degradation and is central for regulating gene expression in eukaryotes. The canonical decapping enzyme Dcp2 is stringently controlled by assembly into a dynamic multi-protein complex together with the 5'-3'exoribonuclease Xrn1. Kinetoplastida lack Dcp2 orthologues but instead rely on the ApaH-like phosphatase ALPH1 for decapping. ALPH1 is composed of a catalytic domain flanked by C- and N-terminal extensions. We show that T. brucei ALPH1 is dimeric in vitro and functions within a complex composed of the trypanosome Xrn1 ortholog XRNA and four proteins unique to Kinetoplastida, including two RNA-binding proteins and a CMGC-family protein kinase. All ALPH1-associated proteins share a unique and dynamic localization to a structure at the posterior pole of the cell, anterior to the microtubule plus ends. XRNA affinity capture in T. cruzi recapitulates this interaction network. The ALPH1 N-terminus is not required for viability in culture, but essential for posterior pole localization. The C-terminus, in contrast, is required for localization to all RNA granule types, as well as for dimerization and interactions with XRNA and the CMGC kinase, suggesting possible regulatory mechanisms. Most significantly, the trypanosome decapping complex has a unique composition, differentiating the process from opisthokonts.
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Affiliation(s)
| | - Natalia Katarzyna Karolak
- Biological and Chemical Research Centre, Department of Chemistry, University of Warsaw, Warsaw, Poland
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | | | - Bernardo Gabiatti
- Biocenter, University of Würzburg, Würzburg, Germany
- Carlos Chagas Institute (ICC), FIOCRUZ/PR, Curitiba, Brazil
| | | | - Anna Zavřelová
- Department of Parasitology, Faculty of Science, Charles University in Prague, Biocev, Vestec, Czech Republic
| | | | | | - Silke Braune
- Biocenter, University of Würzburg, Würzburg, Germany
| | - Claudia Moreira
- Biocenter, University of Würzburg, Würzburg, Germany
- Carlos Chagas Institute (ICC), FIOCRUZ/PR, Curitiba, Brazil
| | - Amelie Eder
- Biocenter, University of Würzburg, Würzburg, Germany
| | - Carina Goos
- Biocenter, University of Würzburg, Würzburg, Germany
| | - Mark Field
- School of Life Sciences, University of Dundee, Dundee, UK
- Biology Centre, Czech Academy of Sciences, Institute of Parasitology, České Budějovice, Czech Republic
| | - Mark Carrington
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Fabiola Holetz
- Carlos Chagas Institute (ICC), FIOCRUZ/PR, Curitiba, Brazil
| | - Maria Wiktoria Górna
- Biological and Chemical Research Centre, Department of Chemistry, University of Warsaw, Warsaw, Poland
| | - Martin Zoltner
- Department of Parasitology, Faculty of Science, Charles University in Prague, Biocev, Vestec, Czech Republic
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4
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Bishola Tshitenge T, Clayton C. The Trypanosoma brucei RNA-binding protein DRBD18 ensures correct mRNA trans splicing and polyadenylation patterns. RNA (NEW YORK, N.Y.) 2022; 28:1239-1262. [PMID: 35793904 PMCID: PMC9380746 DOI: 10.1261/rna.079258.122] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Accepted: 06/23/2022] [Indexed: 06/15/2023]
Abstract
The parasite Trypanosoma brucei grows as bloodstream forms in mammals, and as procyclic forms in tsetse flies. Transcription is polycistronic, all mRNAs are trans spliced, and polyadenylation sites are defined by downstream splicing signals. Expression regulation therefore depends heavily on post-transcriptional mechanisms. The RNA-binding protein DRBD18 was previously implicated in the export of some mRNAs from the nucleus in procyclic forms. It copurifies the outer ring of the nuclear pore, mRNA export factors and exon-junction-complex proteins. We show that for more than 200 mRNAs, DRBD18 depletion caused preferential accumulation of versions with shortened 3'-untranslated regions, arising from use of polyadenylation sites that were either undetectable or rarely seen in nondepleted cells. The shortened mRNAs were often, but not always, more abundant in depleted cells than the corresponding longer versions in normal cells. Their appearance was linked to the appearance of trans-spliced, polyadenylated RNAs containing only downstream 3'-untranslated region-derived sequences. Experiments with one mRNA suggested that nuclear retention alone, through depletion of MEX67, did not affect mRNA length, suggesting a specific effect of DRBD18 on processing. DRBD18-bound mRNAs were enriched in polypyrimidine tract motifs, and DRBD18 was found in both the nucleus and the cytoplasm. We therefore suggest that in the nucleus, DRBD18 might bind to polypyrimidine tracts in 3'-UTRs of mRNA precursors. Such binding might both prevent recognition of mRNA-internal polypyrimidine tracts by splicing factors, and promote export of the processed bound mRNAs to the cytosol.
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Affiliation(s)
| | - Christine Clayton
- Heidelberg University Center for Molecular Biology (ZMBH), D69120 Heidelberg, Germany
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5
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Chen J, Zhang Y, Chen D, Wang T, Yin W, Yang HH, Xu Y, Chen JX, Dai Z, Zou X. Toehold-mediated ligation-free rolling circle amplification enables sensitive and rapid imaging of messenger RNAs in situ in cells. Anal Chim Acta 2021; 1160:338463. [PMID: 33894961 DOI: 10.1016/j.aca.2021.338463] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 03/10/2021] [Accepted: 03/23/2021] [Indexed: 11/27/2022]
Abstract
In situ analysis of tumor-related messenger RNAs (mRNAs) is significant in identifying cancer cells at the genetic level in the early stage. Rolling circle amplification (RCA)-based methods are primary tools for in situ mRNA assay, however, the necessary ligation reaction not only shows low ligation efficiency, but also greatly prolongs the assay time that increases the risk of cells losing and mRNAs leakage. In this work, we propose a novel toehold-mediated ligation-free RCA (TMLFRCA) on a designed structure-switchable dumbbell-shaped probe (SDP). Target mRNA can specifically activate SDP from its circular form by toehold strand displacement, thereby initiates in situ RCA for mRNA imaging with the help of a short DNA primer. For the proof-of-concept demonstration, the TK1 mRNA was sensitively detected by TMLFRCA in less than 3.5 h with a limit of detection (LOD) of 0.39 fM (corresponds to 2.39×108copiesL-1), and significantly improved specificity capable for distinguishing single base difference. The sensitivity of the TMLFRCA for TK1 mRNA in situ assay is ∼29-fold and ∼7-fold higher than that of FISH and ligase-assisted RCA method, respectively, which enables the TMLFRCA method capability of highly sensitive and specific distinction mRNA expression levels between cancer cells and normal cells. We believe this TMLFRCA strategy would be of great value in both basic research and clinical diagnosis.
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Affiliation(s)
- Jun Chen
- School of Pharmaceutical Sciences, Southern Medical University, Guangzhou, 510515, PR China
| | - Yanfei Zhang
- School of Chemistry, Sun Yat-Sen University, 135 Xingang West Road, Guangzhou, 510275, PR China
| | - Danping Chen
- School of Chemistry, Sun Yat-Sen University, 135 Xingang West Road, Guangzhou, 510275, PR China
| | - Tianchen Wang
- School of Chemistry, Sun Yat-Sen University, 135 Xingang West Road, Guangzhou, 510275, PR China
| | - Wen Yin
- School of Chemistry, Sun Yat-Sen University, 135 Xingang West Road, Guangzhou, 510275, PR China
| | - Hui-Hui Yang
- School of Chemistry, Sun Yat-Sen University, 135 Xingang West Road, Guangzhou, 510275, PR China
| | - Yuzhi Xu
- School of Chemistry, Sun Yat-Sen University, 135 Xingang West Road, Guangzhou, 510275, PR China
| | - Jin-Xiang Chen
- School of Pharmaceutical Sciences, Southern Medical University, Guangzhou, 510515, PR China
| | - Zong Dai
- School of Biomedical Engineering, Sun Yat-Sen University, Guangzhou, 511400, PR China.
| | - Xiaoyong Zou
- School of Chemistry, Sun Yat-Sen University, 135 Xingang West Road, Guangzhou, 510275, PR China
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6
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Kramer S, Meyer-Natus E, Stigloher C, Thoma H, Schnaufer A, Engstler M. Parallel monitoring of RNA abundance, localization and compactness with correlative single molecule FISH on LR White embedded samples. Nucleic Acids Res 2021; 49:e14. [PMID: 33275141 PMCID: PMC7897490 DOI: 10.1093/nar/gkaa1142] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 10/16/2020] [Accepted: 11/17/2020] [Indexed: 01/19/2023] Open
Abstract
Single mRNA molecules are frequently detected by single molecule fluorescence in situ hybridization (smFISH) using branched DNA technology. While providing strong and background-reduced signals, the method is inefficient in detecting mRNAs within dense structures, in monitoring mRNA compactness and in quantifying abundant mRNAs. To overcome these limitations, we have hybridized slices of high pressure frozen, freeze-substituted and LR White embedded cells (LR White smFISH). mRNA detection is physically restricted to the surface of the resin. This enables single molecule detection of RNAs with accuracy comparable to RNA sequencing, irrespective of their abundance, while at the same time providing spatial information on RNA localization that can be complemented with immunofluorescence and electron microscopy, as well as array tomography. Moreover, LR White embedding restricts the number of available probe pair recognition sites for each mRNA to a small subset. As a consequence, differences in signal intensities between RNA populations reflect differences in RNA structures, and we show that the method can be employed to determine mRNA compactness. We apply the method to answer some outstanding questions related to trans-splicing, RNA granules and mitochondrial RNA editing in single-cellular trypanosomes and we show an example of differential gene expression in the metazoan Caenorhabditis elegans.
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Affiliation(s)
- Susanne Kramer
- Zell- und Entwicklungsbiologie, Biozentrum, Universität Würzburg, Würzburg, Germany
| | | | - Christian Stigloher
- Zell- und Entwicklungsbiologie, Biozentrum, Universität Würzburg, Würzburg, Germany.,Imaging Core Facility, Biozentrum, Universität Würzburg, Würzburg, Germany
| | - Hanna Thoma
- Zell- und Entwicklungsbiologie, Biozentrum, Universität Würzburg, Würzburg, Germany
| | - Achim Schnaufer
- Institute for Immunology & Infection Research, University of Edinburgh, Edinburgh, UK
| | - Markus Engstler
- Zell- und Entwicklungsbiologie, Biozentrum, Universität Würzburg, Würzburg, Germany
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7
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Abstract
The passage of mRNAs through the nuclear pores into the cytoplasm is essential in all eukaryotes. For regulation, mRNA export is tightly connected to the full machinery of nuclear mRNA processing, starting at transcription. Export competence of pre-mRNAs gradually increases by both transient and permanent interactions with multiple RNA processing and export factors. mRNA export is best understood in opisthokonts, with limited knowledge in plants and protozoa. Here, I review and compare nuclear mRNA processing and export between opisthokonts and Trypanosoma brucei. The parasite has many unusual features in nuclear mRNA processing, such as polycistronic transcription and trans-splicing. It lacks several nuclear complexes and nuclear-pore-associated proteins that in opisthokonts play major roles in mRNA export. As a consequence, trypanosome mRNA export control is not tight and export can even start co-transcriptionally. Whether trypanosomes regulate mRNA export at all, or whether leakage of immature mRNA to the cytoplasm is kept to a low level by a fast kinetics of mRNA processing remains to be investigated. mRNA export had to be present in the last common ancestor of eukaryotes. Trypanosomes are evolutionary very distant from opisthokonts and a comparison helps understanding the evolution of mRNA export.
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8
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Hirata R, Hirakawa K, Shimada N, Watanabe K, Ohtsuki T. Fluorescence lifetime probes for detection of RNA degradation. Analyst 2021; 146:277-282. [PMID: 33135018 DOI: 10.1039/d0an01230k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
To investigate RNA degradation in live cells, detection methods that do not require RNA extraction from cells are necessary. In this study, we examined the utility of fluorescence lifetime measurements using a probe attached to the end of an RNA molecule for detecting RNA degradation. We optimized a short fluorescein-labeled RNA sequence whose fluorescence lifetime varied significantly before and after degradation. The selected HHG-fluorescein sequence (H = U, C, or A) is a promising RNA labeling unit (fluorescence lifetime probe) for live cell imaging of RNA degradation.
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Affiliation(s)
- Riku Hirata
- Department of Interdisciplinary Science and Engineering in Health Systems, Okayama University, Okayama, Japan.
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9
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Goos C, Dejung M, Wehman AM, M-Natus E, Schmidt J, Sunter J, Engstler M, Butter F, Kramer S. Trypanosomes can initiate nuclear export co-transcriptionally. Nucleic Acids Res 2019; 47:266-282. [PMID: 30418648 PMCID: PMC6326799 DOI: 10.1093/nar/gky1136] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 10/25/2018] [Indexed: 02/03/2023] Open
Abstract
The nuclear envelope serves as important messenger RNA (mRNA) surveillance system. In yeast and human, several control systems act in parallel to prevent nuclear export of unprocessed mRNAs. Trypanosomes lack homologues to most of the involved proteins and their nuclear mRNA metabolism is non-conventional exemplified by polycistronic transcription and mRNA processing by trans-splicing. We here visualized nuclear export in trypanosomes by intra- and intermolecular multi-colour single molecule FISH. We found that, in striking contrast to other eukaryotes, the initiation of nuclear export requires neither the completion of transcription nor splicing. Nevertheless, we show that unspliced mRNAs are mostly prevented from reaching the nucleus-distant cytoplasm and instead accumulate at the nuclear periphery in cytoplasmic nuclear periphery granules (NPGs). Further characterization of NPGs by electron microscopy and proteomics revealed that the granules are located at the cytoplasmic site of the nuclear pores and contain most cytoplasmic RNA-binding proteins but none of the major translation initiation factors, consistent with a function in preventing faulty mRNAs from reaching translation. Our data indicate that trypanosomes regulate the completion of nuclear export, rather than the initiation. Nuclear export control remains poorly understood, in any organism, and the described way of control may not be restricted to trypanosomes.
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Affiliation(s)
- Carina Goos
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Mario Dejung
- Institute of Molecular Biology (IMB), Ackermannweg 4, 55128 Mainz, Germany
| | - Ann M Wehman
- Rudolf Virchow Center, University of Würzburg, Josef-Schneider-Strasse 2, 97080 Würzburg, Germany
| | - Elisabeth M-Natus
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Johannes Schmidt
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Jack Sunter
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford OX3 0BP, UK
| | - Markus Engstler
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Falk Butter
- Institute of Molecular Biology (IMB), Ackermannweg 4, 55128 Mainz, Germany
| | - Susanne Kramer
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
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10
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Efficient and specific oligo-based depletion of rRNA. Sci Rep 2019; 9:12281. [PMID: 31439880 PMCID: PMC6706579 DOI: 10.1038/s41598-019-48692-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 08/06/2019] [Indexed: 01/09/2023] Open
Abstract
In most organisms, ribosomal RNA (rRNA) contributes to >85% of total RNA. Thus, to obtain useful information from RNA-sequencing (RNA-seq) analyses at reasonable sequencing depth, typically, mature polyadenylated transcripts are enriched or rRNA molecules are depleted. Targeted depletion of rRNA is particularly useful when studying transcripts lacking a poly(A) tail, such as some non-coding RNAs (ncRNAs), most bacterial RNAs and partially degraded or immature transcripts. While several commercially available kits allow effective rRNA depletion, their efficiency relies on a high degree of sequence homology between oligonucleotide probes and the target RNA. This restricts the use of such kits to a limited number of organisms with conserved rRNA sequences. In this study we describe the use of biotinylated oligos and streptavidin-coated paramagnetic beads for the efficient and specific depletion of trypanosomal rRNA. Our approach reduces the levels of the most abundant rRNA transcripts to less than 5% with minimal off-target effects. By adjusting the sequence of the oligonucleotide probes, our approach can be used to deplete rRNAs or other abundant transcripts independent of species. Thus, our protocol provides a useful alternative for rRNA removal where enrichment of polyadenylated transcripts is not an option and commercial kits for rRNA are not available.
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11
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Abstract
In trypanosomes, RNA polymerase II transcription is polycistronic and individual mRNAs are excised by trans-splicing and polyadenylation. The lack of individual gene transcription control is compensated by control of mRNA processing, translation and degradation. Although the basic mechanisms of mRNA decay and translation are evolutionarily conserved, there are also unique aspects, such as the existence of six cap-binding translation initiation factor homologues, a novel decapping enzyme and an mRNA stabilizing complex that is recruited by RNA-binding proteins. High-throughput analyses have identified nearly a hundred regulatory mRNA-binding proteins, making trypanosomes valuable as a model system to investigate post-transcriptional regulation.
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Affiliation(s)
- Christine Clayton
- University of Heidelberg Center for Molecular Biology (ZMBH), Im Neuenheimer Feld 282, D69120 Heidelberg, Germany
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12
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Hughes SC, Simmonds AJ. Drosophila mRNA Localization During Later Development: Past, Present, and Future. Front Genet 2019; 10:135. [PMID: 30899273 PMCID: PMC6416162 DOI: 10.3389/fgene.2019.00135] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 02/11/2019] [Indexed: 12/12/2022] Open
Abstract
Multiple mechanisms tightly regulate mRNAs during their transcription, translation, and degradation. Of these, the physical localization of mRNAs to specific cytoplasmic regions is relatively easy to detect; however, linking localization to functional regulatory roles has been more difficult to establish. Historically, Drosophila melanogaster is a highly effective model to identify localized mRNAs and has helped identify roles for this process by regulating various cell activities. The majority of the well-characterized functional roles for localizing mRNAs to sub-regions of the cytoplasm have come from the Drosophila oocyte and early syncytial embryo. At present, relatively few functional roles have been established for mRNA localization within the relatively smaller, differentiated somatic cell lineages characteristic of later development, beginning with the cellular blastoderm, and the multiple cell lineages that make up the gastrulating embryo, larva, and adult. This review is divided into three parts—the first outlines past evidence for cytoplasmic mRNA localization affecting aspects of cellular activity post-blastoderm development in Drosophila. The majority of these known examples come from highly polarized cell lineages such as differentiating neurons. The second part considers the present state of affairs where we now know that many, if not most mRNAs are localized to discrete cytoplasmic regions in one or more somatic cell lineages of cellularized embryos, larvae or adults. Assuming that the phenomenon of cytoplasmic mRNA localization represents an underlying functional activity, and correlation with the encoded proteins suggests that mRNA localization is involved in far more than neuronal differentiation. Thus, it seems highly likely that past-identified examples represent only a small fraction of localization-based mRNA regulation in somatic cells. The last part highlights recent technological advances that now provide an opportunity for probing the role of mRNA localization in Drosophila, moving beyond cataloging the diversity of localized mRNAs to a similar understanding of how localization affects mRNA activity.
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Affiliation(s)
- Sarah C Hughes
- Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada.,Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Andrew J Simmonds
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
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13
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Adivarahan S, Zenklusen D. Lessons from (pre-)mRNA Imaging. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1203:247-284. [DOI: 10.1007/978-3-030-31434-7_9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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14
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Recent advances in trypanosomatid research: genome organization, expression, metabolism, taxonomy and evolution. Parasitology 2018; 146:1-27. [PMID: 29898792 DOI: 10.1017/s0031182018000951] [Citation(s) in RCA: 104] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Unicellular flagellates of the family Trypanosomatidae are obligatory parasites of invertebrates, vertebrates and plants. Dixenous species are aetiological agents of a number of diseases in humans, domestic animals and plants. Their monoxenous relatives are restricted to insects. Because of the high biological diversity, adaptability to dramatically different environmental conditions, and omnipresence, these protists have major impact on all biotic communities that still needs to be fully elucidated. In addition, as these organisms represent a highly divergent evolutionary lineage, they are strikingly different from the common 'model system' eukaryotes, such as some mammals, plants or fungi. A number of excellent reviews, published over the past decade, were dedicated to specialized topics from the areas of trypanosomatid molecular and cell biology, biochemistry, host-parasite relationships or other aspects of these fascinating organisms. However, there is a need for a more comprehensive review that summarizing recent advances in the studies of trypanosomatids in the last 30 years, a task, which we tried to accomplish with the current paper.
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15
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Wadsworth GM, Parikh RY, Choy JS, Kim HD. mRNA detection in budding yeast with single fluorophores. Nucleic Acids Res 2017; 45:e141. [PMID: 28666354 PMCID: PMC5587780 DOI: 10.1093/nar/gkx568] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Accepted: 06/21/2017] [Indexed: 12/29/2022] Open
Abstract
Quantitative measurement of mRNA levels in single cells is necessary to understand phenotypic variability within an otherwise isogenic population of cells. Single-molecule mRNA Fluorescence In Situ Hybridization (FISH) has been established as the standard method for this purpose, but current protocols require a long region of mRNA to be targeted by multiple DNA probes. Here, we introduce a new single-probe FISH protocol termed sFISH for budding yeast, Saccharomyces cerevisiae using a single DNA probe labeled with a single fluorophore. In sFISH, we markedly improved probe specificity and signal-to-background ratio by using methanol fixation and inclined laser illumination. We show that sFISH reports mRNA changes that correspond to protein levels and gene copy number. Using this new FISH protocol, we can detect >50% of the total target mRNA. We also demonstrate the versatility of sFISH using FRET detection and mRNA isoform profiling as examples. Our FISH protocol with single-fluorophore sensitivity significantly reduces cost and time compared to the conventional FISH protocols and opens up new opportunities to investigate small changes in RNA at the single cell level.
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Affiliation(s)
- Gable M Wadsworth
- School of Physics, Georgia Institute of Technology, 837 State Street, Atlanta, GA 30332-0430, USA
| | - Rasesh Y Parikh
- School of Physics, Georgia Institute of Technology, 837 State Street, Atlanta, GA 30332-0430, USA
| | - John S Choy
- Department of Biology, The Catholic University of America, 620 Michigan Avenue NE, Washington, DC 20064, USA
| | - Harold D Kim
- School of Physics, Georgia Institute of Technology, 837 State Street, Atlanta, GA 30332-0430, USA
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Horvathova I, Voigt F, Kotrys AV, Zhan Y, Artus-Revel CG, Eglinger J, Stadler MB, Giorgetti L, Chao JA. The Dynamics of mRNA Turnover Revealed by Single-Molecule Imaging in Single Cells. Mol Cell 2017; 68:615-625.e9. [PMID: 29056324 DOI: 10.1016/j.molcel.2017.09.030] [Citation(s) in RCA: 122] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Revised: 09/08/2017] [Accepted: 09/21/2017] [Indexed: 01/06/2023]
Abstract
RNA degradation plays a fundamental role in regulating gene expression. In order to characterize the spatiotemporal dynamics of RNA turnover in single cells, we developed a fluorescent biosensor based on dual-color, single-molecule RNA imaging that allows intact transcripts to be distinguished from stabilized degradation intermediates. Using this method, we measured mRNA decay in single cells and found that individual degradation events occur independently within the cytosol and are not enriched within processing bodies. We show that slicing of an mRNA targeted for endonucleolytic cleavage by the RNA-induced silencing complex can be observed in real time in living cells. This methodology provides a framework for investigating the entire life history of individual mRNAs from birth to death in single cells.
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Affiliation(s)
- Ivana Horvathova
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland; University of Basel, 4003 Basel, Switzerland
| | - Franka Voigt
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland
| | - Anna V Kotrys
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland
| | - Yinxiu Zhan
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland; University of Basel, 4003 Basel, Switzerland
| | | | - Jan Eglinger
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland
| | - Michael B Stadler
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland; Swiss Institute of Bioinformatics, 4058 Basel, Switzerland
| | - Luca Giorgetti
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland
| | - Jeffrey A Chao
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland.
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Abstract
5’-3’ decay is the major mRNA decay pathway in many eukaryotes, including trypanosomes. After deadenylation, mRNAs are decapped by the nudix hydrolase DCP2 of the decapping complex and finally degraded by the 5’-3’ exoribonuclease. Uniquely, trypanosomes lack homologues to all subunits of the decapping complex, while deadenylation and 5’-3’ degradation are conserved. Here, I show that the parasites use an ApaH-like phosphatase (ALPH1) as their major mRNA decapping enzyme. The protein was recently identified as a novel trypanosome stress granule protein and as involved in mRNA binding. A fraction of ALPH1 co-localises exclusively with the trypanosome 5’-3’ exoribonuclease XRNA to a special granule at the posterior pole of the cell, indicating a connection between the two enzymes. RNAi depletion of ALPH1 is lethal and causes a massive increase in total mRNAs that are deadenylated, but have not yet started 5’-3’ decay. These data suggest that ALPH1 acts downstream of deadenylation and upstream of mRNA degradation, consistent with a function in mRNA decapping. In vitro experiments show that recombinant, N-terminally truncated ALHP1 protein, but not a catalytically inactive mutant, sensitises the capped trypanosome spliced leader RNA to yeast Xrn1, but only if an RNA 5’ polyphosphatase is included. This indicates that the decapping mechanism of ALPH1 differs from the decapping mechanism of Dcp2 by leaving more than one phosphate group at the mRNA’s 5’ end. This is the first reported function of a eukaryotic ApaH-like phosphatase, a bacterial-derived class of enzymes present in all phylogenetic super-groups of the eukaryotic kingdom. The substrates of eukaryotic ApaH-like phosphatases are unknown. However, the substrate of the related bacterial enzyme ApaH, diadenosine tetraphosphate, is highly reminiscent of a eukaryotic mRNA cap. Eukaryotic mRNAs are stabilised by a 5’ cap and one important step in mRNA decay is the removal of this cap by the nudix domain protein Dcp2 of the decapping complex. The decapping complex is highly conserved throughout eukaryotes, with the exception of trypanosomes that lack the entire complex. Here, I show that trypanosomes have evolved to use an ApaH-like phosphatase instead of a nudix domain protein as their major decapping enzyme. This work closes an important gap in the knowledge of trypanosome mRNA metabolism. Moreover, this is the first reported function of an ApaH-like phosphatase, a bacterial derived class of enzymes that are widespread throughout eukaryotes.
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Affiliation(s)
- Susanne Kramer
- Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany
- * E-mail:
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