1
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Bao N, Wang Z, Fu J, Dong H, Jin Y. RNA structure in alternative splicing regulation: from mechanism to therapy. Acta Biochim Biophys Sin (Shanghai) 2024. [PMID: 39034824 DOI: 10.3724/abbs.2024119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/23/2024] Open
Abstract
Alternative splicing is a highly intricate process that plays a crucial role in post-transcriptional regulation and significantly expands the functional proteome of a limited number of coding genes in eukaryotes. Its regulation is multifactorial, with RNA structure exerting a significant impact. Aberrant RNA conformations lead to dysregulation of splicing patterns, which directly affects the manifestation of disease symptoms. In this review, the molecular mechanisms of RNA secondary structure-mediated splicing regulation are summarized, with a focus on the complex interplay between aberrant RNA conformations and disease phenotypes resulted from splicing defects. This study also explores additional factors that reshape structural conformations, enriching our understanding of the mechanistic network underlying structure-mediated splicing regulation. In addition, an emphasis has been placed on the clinical role of targeting aberrant splicing corrections in human diseases. The principal mechanisms of action behind this phenomenon are described, followed by a discussion of prospective development strategies and pertinent challenges.
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2
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Ma M, Szavits-Nossan J, Singh A, Grima R. Analysis of a detailed multi-stage model of stochastic gene expression using queueing theory and model reduction. Math Biosci 2024; 373:109204. [PMID: 38710441 DOI: 10.1016/j.mbs.2024.109204] [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: 01/23/2024] [Revised: 04/03/2024] [Accepted: 04/29/2024] [Indexed: 05/08/2024]
Abstract
We introduce a biologically detailed, stochastic model of gene expression describing the multiple rate-limiting steps of transcription, nuclear pre-mRNA processing, nuclear mRNA export, cytoplasmic mRNA degradation and translation of mRNA into protein. The processes in sub-cellular compartments are described by an arbitrary number of processing stages, thus accounting for a significantly finer molecular description of gene expression than conventional models such as the telegraph, two-stage and three-stage models of gene expression. We use two distinct tools, queueing theory and model reduction using the slow-scale linear-noise approximation, to derive exact or approximate analytic expressions for the moments or distributions of nuclear mRNA, cytoplasmic mRNA and protein fluctuations, as well as lower bounds for their Fano factors in steady-state conditions. We use these to study the phase diagram of the stochastic model; in particular we derive parametric conditions determining three types of transitions in the properties of mRNA fluctuations: from sub-Poissonian to super-Poissonian noise, from high noise in the nucleus to high noise in the cytoplasm, and from a monotonic increase to a monotonic decrease of the Fano factor with the number of processing stages. In contrast, protein fluctuations are always super-Poissonian and show weak dependence on the number of mRNA processing stages. Our results delineate the region of parameter space where conventional models give qualitatively incorrect results and provide insight into how the number of processing stages, e.g. the number of rate-limiting steps in initiation, splicing and mRNA degradation, shape stochastic gene expression by modulation of molecular memory.
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Affiliation(s)
- Muhan Ma
- School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, UK
| | | | - Abhyudai Singh
- Department of Electrical and Computer Engineering, University of Delaware, Newark DE 19716, USA
| | - Ramon Grima
- School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, UK.
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3
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Merens HE, Choquet K, Baxter-Koenigs AR, Churchman LS. Timing is everything: advances in quantifying splicing kinetics. Trends Cell Biol 2024:S0962-8924(24)00070-9. [PMID: 38777664 DOI: 10.1016/j.tcb.2024.03.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Revised: 03/26/2024] [Accepted: 03/27/2024] [Indexed: 05/25/2024]
Abstract
Splicing is a highly regulated process critical for proper pre-mRNA maturation and the maintenance of a healthy cellular environment. Splicing events are impacted by ongoing transcription, neighboring splicing events, and cis and trans regulatory factors on the respective pre-mRNA transcript. Within this complex regulatory environment, splicing kinetics have the potential to influence splicing outcomes but have historically been challenging to study in vivo. In this review, we highlight recent technological advancements that have enabled measurements of global splicing kinetics and of the variability of splicing kinetics at single introns. We demonstrate how identifying features that are correlated with splicing kinetics has increased our ability to form potential models for how splicing kinetics may be regulated in vivo.
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Affiliation(s)
- Hope E Merens
- Harvard University, Department of Genetics, Boston, MA, USA
| | - Karine Choquet
- University of Sherbrooke, Department of Biochemistry and Functional Genomics, Sherbrooke, Québec, Canada
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4
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Coté A, O'Farrell A, Dardani I, Dunagin M, Coté C, Wan Y, Bayatpour S, Drexler HL, Alexander KA, Chen F, Wassie AT, Patel R, Pham K, Boyden ES, Berger S, Phillips-Cremins J, Churchman LS, Raj A. Post-transcriptional splicing can occur in a slow-moving zone around the gene. eLife 2024; 12:RP91357. [PMID: 38577979 PMCID: PMC10997330 DOI: 10.7554/elife.91357] [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] [Indexed: 04/06/2024] Open
Abstract
Splicing is the stepwise molecular process by which introns are removed from pre-mRNA and exons are joined together to form mature mRNA sequences. The ordering and spatial distribution of these steps remain controversial, with opposing models suggesting splicing occurs either during or after transcription. We used single-molecule RNA FISH, expansion microscopy, and live-cell imaging to reveal the spatiotemporal distribution of nascent transcripts in mammalian cells. At super-resolution levels, we found that pre-mRNA formed clouds around the transcription site. These clouds indicate the existence of a transcription-site-proximal zone through which RNA move more slowly than in the nucleoplasm. Full-length pre-mRNA undergo continuous splicing as they move through this zone following transcription, suggesting a model in which splicing can occur post-transcriptionally but still within the proximity of the transcription site, thus seeming co-transcriptional by most assays. These results may unify conflicting reports of co-transcriptional versus post-transcriptional splicing.
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Affiliation(s)
- Allison Coté
- Department of Bioengineering, University of PennsylvaniaPhiladelphiaUnited States
| | - Aoife O'Farrell
- Department of Bioengineering, University of PennsylvaniaPhiladelphiaUnited States
| | - Ian Dardani
- Department of Bioengineering, University of PennsylvaniaPhiladelphiaUnited States
| | - Margaret Dunagin
- Department of Bioengineering, University of PennsylvaniaPhiladelphiaUnited States
| | - Chris Coté
- Department of Bioengineering, University of PennsylvaniaPhiladelphiaUnited States
| | - Yihan Wan
- School of Life Sciences, Westlake UniversityHangzhouChina
| | - Sareh Bayatpour
- Department of Bioengineering, University of PennsylvaniaPhiladelphiaUnited States
| | - Heather L Drexler
- Department of Genetics, Blavatnik Institute, Harvard Medical SchoolBostonUnited States
| | - Katherine A Alexander
- Department of Cell and Developmental Biology, Penn Institute of Epigenetics, Perelman School of Medicine, University of PennsylvaniaPhiladelphiaUnited States
| | - Fei Chen
- Broad Institute of MIT and HarvardCambridgeUnited States
| | - Asmamaw T Wassie
- Department of Cell and Molecular Biology, University of PennsylvaniaPhiladelphiaUnited States
| | - Rohan Patel
- Department of Bioengineering, University of PennsylvaniaPhiladelphiaUnited States
| | - Kenneth Pham
- Department of Cell and Molecular Biology, University of PennsylvaniaPhiladelphiaUnited States
| | - Edward S Boyden
- Departments of Biological Engineering and Brain and Cognitive Sciences, Media Lab and McGovern Institute, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Shelly Berger
- Department of Cell and Developmental Biology, Penn Institute of Epigenetics, Perelman School of Medicine, University of PennsylvaniaPhiladelphiaUnited States
| | | | - L Stirling Churchman
- Department of Genetics, Blavatnik Institute, Harvard Medical SchoolBostonUnited States
| | - Arjun Raj
- Department of Bioengineering, University of PennsylvaniaPhiladelphiaUnited States
- Department of Genetics, Perelman School of Medicine, University of PennsylvaniaPhiladelphiaUnited States
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5
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Szabo B, Mandl TC, Woldrich B, Diensthuber G, Martin D, Jantsch MF, Licht K. RNA Pol II-dependent transcription efficiency fine-tunes A-to-I editing levels. Genome Res 2024; 34:231-242. [PMID: 38471738 PMCID: PMC10984384 DOI: 10.1101/gr.277686.123] [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: 01/22/2023] [Accepted: 02/15/2024] [Indexed: 03/14/2024]
Abstract
A-to-I RNA editing is a widespread epitranscriptomic phenomenon leading to the conversion of adenosines to inosines, which are primarily interpreted as guanosines by cellular machines. Consequently, A-to-I editing can alter splicing or lead to recoding of transcripts. As misregulation of editing can cause a variety of human diseases, A-to-I editing requires tight regulation of the extent of deamination, particularly in protein-coding regions. The bulk of A-to-I editing occurs cotranscriptionally. Thus, we studied A-to-I editing regulation in the context of transcription and pre-mRNA processing. We show that stimulation of transcription impacts editing levels. Activation of the transcription factor MYC leads to an up-regulation of A-to-I editing, particularly in transcripts that are suppressed upon MYC activation. Moreover, low pre-mRNA synthesis rates and low pre-mRNA expression levels support high levels of editing. We also show that editing levels greatly differ between nascent pre-mRNA and mRNA in a cellular system, as well as in mouse tissues. Editing levels can increase or decrease from pre-mRNA to mRNA and can vary across editing targets and across tissues, showing that pre-mRNA processing is an important layer of editing regulation. Several lines of evidence suggest that the differences emerge during pre-mRNA splicing. Moreover, actinomycin D treatment of primary neuronal cells and editing level analysis suggests that regulation of editing levels also depends on transcription.
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Affiliation(s)
- Brigitta Szabo
- Department of Cell and Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Therese C Mandl
- Department of Cell and Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Bernhard Woldrich
- Department of Cell and Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Gregor Diensthuber
- Department of Cell and Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, A-1090 Vienna, Austria
| | - David Martin
- Department of Cell and Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Michael F Jantsch
- Department of Cell and Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Konstantin Licht
- Department of Cell and Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, A-1090 Vienna, Austria
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6
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Abrhámová K, Groušlová M, Valentová A, Hao X, Liu B, Převorovský M, Gahura O, Půta F, Sunnerhagen P, Folk P. Truncating the spliceosomal 'rope protein' Prp45 results in Htz1 dependent phenotypes. RNA Biol 2024; 21:1-17. [PMID: 38711165 PMCID: PMC11085953 DOI: 10.1080/15476286.2024.2348896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/24/2024] [Indexed: 05/08/2024] Open
Abstract
Spliceosome assembly contributes an important but incompletely understood aspect of splicing regulation. Prp45 is a yeast splicing factor which runs as an extended fold through the spliceosome, and which may be important for bringing its components together. We performed a whole genome analysis of the genetic interaction network of the truncated allele of PRP45 (prp45(1-169)) using synthetic genetic array technology and found chromatin remodellers and modifiers as an enriched category. In agreement with related studies, H2A.Z-encoding HTZ1, and the components of SWR1, INO80, and SAGA complexes represented prominent interactors, with htz1 conferring the strongest growth defect. Because the truncation of Prp45 disproportionately affected low copy number transcripts of intron-containing genes, we prepared strains carrying intronless versions of SRB2, VPS75, or HRB1, the most affected cases with transcription-related function. Intron removal from SRB2, but not from the other genes, partly repaired some but not all the growth phenotypes identified in the genetic screen. The interaction of prp45(1-169) and htz1Δ was detectable even in cells with SRB2 intron deleted (srb2Δi). The less truncated variant, prp45(1-330), had a synthetic growth defect with htz1Δ at 16°C, which also persisted in the srb2Δi background. Moreover, htz1Δ enhanced prp45(1-330) dependent pre-mRNA hyper-accumulation of both high and low efficiency splicers, genes ECM33 and COF1, respectively. We conclude that while the expression defects of low expression intron-containing genes contribute to the genetic interactome of prp45(1-169), the genetic interactions between prp45 and htz1 alleles demonstrate the sensitivity of spliceosome assembly, delayed in prp45(1-169), to the chromatin environment.
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Affiliation(s)
- Kateřina Abrhámová
- Department of Cell Biology, Faculty of Science, Charles University, Praha, Czech Republic
| | - Martina Groušlová
- Department of Cell Biology, Faculty of Science, Charles University, Praha, Czech Republic
| | - Anna Valentová
- Department of Cell Biology, Faculty of Science, Charles University, Praha, Czech Republic
| | - Xinxin Hao
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Beidong Liu
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Martin Převorovský
- Department of Cell Biology, Faculty of Science, Charles University, Praha, Czech Republic
| | - Ondřej Gahura
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic
| | - František Půta
- Department of Cell Biology, Faculty of Science, Charles University, Praha, Czech Republic
| | - Per Sunnerhagen
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Petr Folk
- Department of Cell Biology, Faculty of Science, Charles University, Praha, Czech Republic
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7
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Shenasa H, Bentley DL. Pre-mRNA splicing and its cotranscriptional connections. Trends Genet 2023; 39:672-685. [PMID: 37236814 PMCID: PMC10524715 DOI: 10.1016/j.tig.2023.04.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 04/23/2023] [Accepted: 04/26/2023] [Indexed: 05/28/2023]
Abstract
Transcription of eukaryotic genes by RNA polymerase II (Pol II) yields RNA precursors containing introns that must be spliced out and the flanking exons ligated together. Splicing is catalyzed by a dynamic ribonucleoprotein complex called the spliceosome. Recent evidence has shown that a large fraction of splicing occurs cotranscriptionally as the RNA chain is extruded from Pol II at speeds of up to 5 kb/minute. Splicing is more efficient when it is tethered to the transcription elongation complex, and this linkage permits functional coupling of splicing with transcription. We discuss recent progress that has uncovered a network of connections that link splicing to transcript elongation and other cotranscriptional RNA processing events.
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Affiliation(s)
- Hossein Shenasa
- Department of Biochemistry and Molecular Genetics, RNA Bioscience Initiative, University of Colorado School of Medicine, PO Box 6511, Aurora, CO 80045, USA
| | - David L Bentley
- Department of Biochemistry and Molecular Genetics, RNA Bioscience Initiative, University of Colorado School of Medicine, PO Box 6511, Aurora, CO 80045, USA.
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8
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Choquet K, Baxter-Koenigs AR, Dülk SL, Smalec BM, Rouskin S, Churchman LS. Pre-mRNA splicing order is predetermined and maintains splicing fidelity across multi-intronic transcripts. Nat Struct Mol Biol 2023; 30:1064-1076. [PMID: 37443198 PMCID: PMC10653200 DOI: 10.1038/s41594-023-01035-2] [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: 07/19/2022] [Accepted: 06/13/2023] [Indexed: 07/15/2023]
Abstract
Combinatorially, intron excision within a given nascent transcript could proceed down any of thousands of paths, each of which would expose different dynamic landscapes of cis-elements and contribute to alternative splicing. In this study, we found that post-transcriptional multi-intron splicing order in human cells is largely predetermined, with most genes spliced in one or a few predominant orders. Strikingly, these orders were conserved across cell types and stages of motor neuron differentiation. Introns flanking alternatively spliced exons were frequently excised last, after their neighboring introns. Perturbations to the spliceosomal U2 snRNA altered the preferred splicing order of many genes, and these alterations were associated with the retention of other introns in the same transcript. In one gene, early removal of specific introns was sufficient to induce delayed excision of three proximal introns, and this delay was caused by two distinct cis-regulatory mechanisms. Together, our results demonstrate that multi-intron splicing order in human cells is predetermined, is influenced by a component of the spliceosome and ensures splicing fidelity across long pre-mRNAs.
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Affiliation(s)
- Karine Choquet
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | | | - Sarah-Luisa Dülk
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Brendan M Smalec
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Silvi Rouskin
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - L Stirling Churchman
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, USA.
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9
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Ruperao P, Rangan P, Shah T, Thakur V, Kalia S, Mayes S, Rathore A. The Progression in Developing Genomic Resources for Crop Improvement. Life (Basel) 2023; 13:1668. [PMID: 37629524 PMCID: PMC10455509 DOI: 10.3390/life13081668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 07/21/2023] [Accepted: 07/25/2023] [Indexed: 08/27/2023] Open
Abstract
Sequencing technologies have rapidly evolved over the past two decades, and new technologies are being continually developed and commercialized. The emerging sequencing technologies target generating more data with fewer inputs and at lower costs. This has also translated to an increase in the number and type of corresponding applications in genomics besides enhanced computational capacities (both hardware and software). Alongside the evolving DNA sequencing landscape, bioinformatics research teams have also evolved to accommodate the increasingly demanding techniques used to combine and interpret data, leading to many researchers moving from the lab to the computer. The rich history of DNA sequencing has paved the way for new insights and the development of new analysis methods. Understanding and learning from past technologies can help with the progress of future applications. This review focuses on the evolution of sequencing technologies, their significant enabling role in generating plant genome assemblies and downstream applications, and the parallel development of bioinformatics tools and skills, filling the gap in data analysis techniques.
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Affiliation(s)
- Pradeep Ruperao
- Center of Excellence in Genomics and Systems Biology, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad 502324, India
| | - Parimalan Rangan
- ICAR-National Bureau of Plant Genetic Resources, PUSA Campus, New Delhi 110012, India;
| | - Trushar Shah
- International Institute of Tropical Agriculture (IITA), Nairobi 30709-00100, Kenya;
| | - Vivek Thakur
- Department of Systems & Computational Biology, School of Life Sciences, University of Hyderabad, Hyderabad 500046, India;
| | - Sanjay Kalia
- Department of Biotechnology, Ministry of Science and Technology, Government of India, New Delhi 110003, India;
| | - Sean Mayes
- Center of Excellence in Genomics and Systems Biology, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad 502324, India
| | - Abhishek Rathore
- Excellence in Breeding, International Maize and Wheat Improvement Center (CIMMYT), Hyderabad 502324, India
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10
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Gohr A, Iñiguez LP, Torres-Méndez A, Bonnal S, Irimia M. Insplico: effective computational tool for studying splicing order of adjacent introns genome-wide with short and long RNA-seq reads. Nucleic Acids Res 2023; 51:e56. [PMID: 37026474 PMCID: PMC10250204 DOI: 10.1093/nar/gkad244] [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: 07/19/2022] [Revised: 03/13/2023] [Accepted: 03/23/2023] [Indexed: 04/08/2023] Open
Abstract
Although splicing occurs largely co-transcriptionally, the order by which introns are removed does not necessarily follow the order in which they are transcribed. Whereas several genomic features are known to influence whether or not an intron is spliced before its downstream neighbor, multiple questions related to adjacent introns' splicing order (AISO) remain unanswered. Here, we present Insplico, the first standalone software for quantifying AISO that works with both short and long read sequencing technologies. We first demonstrate its applicability and effectiveness using simulated reads and by recapitulating previously reported AISO patterns, which unveiled overlooked biases associated with long read sequencing. We next show that AISO around individual exons is remarkably constant across cell and tissue types and even upon major spliceosomal disruption, and it is evolutionarily conserved between human and mouse brains. We also establish a set of universal features associated with AISO patterns across various animal and plant species. Finally, we used Insplico to investigate AISO in the context of tissue-specific exons, particularly focusing on SRRM4-dependent microexons. We found that the majority of such microexons have non-canonical AISO, in which the downstream intron is spliced first, and we suggest two potential modes of SRRM4 regulation of microexons related to their AISO and various splicing-related features. Insplico is available on gitlab.com/aghr/insplico.
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Affiliation(s)
- André Gohr
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Luis P Iñiguez
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Antonio Torres-Méndez
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Sophie Bonnal
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Manuel Irimia
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain
- Universitat Pompeu Fabra (UPF), Barcelona, Spain
- ICREA, Barcelona, Spain
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11
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Marquardt S, Petrillo E, Manavella PA. Cotranscriptional RNA processing and modification in plants. THE PLANT CELL 2023; 35:1654-1670. [PMID: 36259932 PMCID: PMC10226594 DOI: 10.1093/plcell/koac309] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 10/14/2022] [Indexed: 05/30/2023]
Abstract
The activities of RNA polymerases shape the epigenetic landscape of genomes with profound consequences for genome integrity and gene expression. A fundamental event during the regulation of eukaryotic gene expression is the coordination between transcription and RNA processing. Most primary RNAs mature through various RNA processing and modification events to become fully functional. While pioneering results positioned RNA maturation steps after transcription ends, the coupling between the maturation of diverse RNA species and their transcription is becoming increasingly evident in plants. In this review, we discuss recent advances in our understanding of the crosstalk between RNA Polymerase II, IV, and V transcription and nascent RNA processing of both coding and noncoding RNAs.
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Affiliation(s)
- Sebastian Marquardt
- Department of Plant and Environmental Sciences, Copenhagen Plant Science Centre, University of Copenhagen, Frederiksberg, Denmark
| | - Ezequiel Petrillo
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE-CONICET-UBA), Buenos Aires, C1428EHA, Argentina
| | - Pablo A Manavella
- Instituto de Agrobiotecnología del Litoral (CONICET-UNL), Cátedra de Biología Celular y Molecular, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, Santa Fe 3000, Argentina
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12
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Bhat P, Chow A, Emert B, Ettlin O, Quinodoz SA, Takei Y, Huang W, Blanco MR, Guttman M. 3D genome organization around nuclear speckles drives mRNA splicing efficiency. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.04.522632. [PMID: 36711853 PMCID: PMC9881923 DOI: 10.1101/2023.01.04.522632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The nucleus is highly organized such that factors involved in transcription and processing of distinct classes of RNA are organized within specific nuclear bodies. One such nuclear body is the nuclear speckle, which is defined by high concentrations of protein and non-coding RNA regulators of pre-mRNA splicing. What functional role, if any, speckles might play in the process of mRNA splicing remains unknown. Here we show that genes localized near nuclear speckles display higher spliceosome concentrations, increased spliceosome binding to their pre-mRNAs, and higher co-transcriptional splicing levels relative to genes that are located farther from nuclear speckles. We show that directed recruitment of a pre-mRNA to nuclear speckles is sufficient to drive increased mRNA splicing levels. Finally, we show that gene organization around nuclear speckles is highly dynamic with differential localization between cell types corresponding to differences in Pol II occupancy. Together, our results integrate the longstanding observations of nuclear speckles with the biochemistry of mRNA splicing and demonstrate a critical role for dynamic 3D spatial organization of genomic DNA in driving spliceosome concentrations and controlling the efficiency of mRNA splicing.
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13
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Zhang Q, Zhao F, Wu Z, Zhu D. A simple and robust method for isolating and analyzing chromatin-bound RNAs in Arabidopsis. PLANT METHODS 2022; 18:135. [PMID: 36510301 PMCID: PMC9743689 DOI: 10.1186/s13007-022-00967-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/24/2022] [Accepted: 11/30/2022] [Indexed: 06/17/2023]
Abstract
BACKGROUND Chromatin-bound RNAs are the primary product of transcription that undergo on-chromatin processing such as capping, splicing, and polyadenylation. These processing steps then determine the fate of RNAs. Albeit its vital importance, a simple and robust method for isolating different fractions of chromatin-bound RNAs is missing in plants. RESULT Here, we describe our updated method and the associated step-by-step protocol for chromatin-bound RNAs isolation in A. thaliana. The chromatin-bound RNAs isolation is based on the 1 M UREA wash that removes the majority of non-chromatin-associated proteins from the nucleus, as previously developed in mammalian cells. On-demand, the isolated chromatin-bound RNAs can be either used directly for gene-specific analysis or subject to further rRNA removal and also the optional polyadenylated RNA removal, followed by high-throughput sequencing. Detailed protocols for these procedures are also provided. Comparison of sequencing results of chromatin-bound RNAs with and without polyadenylated RNA removal revealed that a small fraction of CB-RNAs is polyadenylated but not yet fully spliced, representing RNA-processing intermediate on-chromatin. CONCLUSION This optimized chromatin-bound RNAs purification method is simple and robust and can be used to study transcription and its-coupled RNA processing in plants.
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Affiliation(s)
- Qiqi Zhang
- Harbin Institute of Technology, Harbin, 150001, China
- Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Institute of Plant and Food Research, Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Fengli Zhao
- Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Institute of Plant and Food Research, Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Zhe Wu
- Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Institute of Plant and Food Research, Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, 518055, China.
| | - Danling Zhu
- Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Institute of Plant and Food Research, Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, 518055, China.
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14
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Santos F, Capela AM, Mateus F, Nóbrega-Pereira S, Bernardes de Jesus B. Non-coding antisense transcripts: fine regulation of gene expression in cancer. Comput Struct Biotechnol J 2022; 20:5652-5660. [PMID: 36284703 PMCID: PMC9579725 DOI: 10.1016/j.csbj.2022.10.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 10/03/2022] [Accepted: 10/04/2022] [Indexed: 11/14/2022] Open
Abstract
Natural antisense transcripts (NATs) are coding or non-coding RNA sequences transcribed on the opposite direction from the same genomic locus. NATs are widely distributed throughout the human genome and seem to play crucial roles in physiological and pathological processes, through newly described and targeted mechanisms. NATs represent the intricate complexity of the genome organization and constitute another layer of potential targets in disease. Here, we focus on the interesting and unique role of non-coding NATs in cancer, paying particular attention to those acting as miRNA sponges.
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Affiliation(s)
| | | | | | | | - Bruno Bernardes de Jesus
- Corresponding author at: Department of Medical Sciences and Institute of Biomedicine – iBiMED, University of Aveiro, 3810-193 Aveiro, Portugal.
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15
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Transcriptome-Wide Detection of Intron/Exon Definition in the Endogenous Pre-mRNA Transcripts of Mammalian Cells and Its Regulation by Depolarization. Int J Mol Sci 2022; 23:ijms231710157. [PMID: 36077555 PMCID: PMC9456152 DOI: 10.3390/ijms231710157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 08/31/2022] [Accepted: 09/01/2022] [Indexed: 11/23/2022] Open
Abstract
Pairing of splice sites across an intron or exon is the central point of intron or exon definition in pre-mRNA splicing with the latter mode proposed for most mammalian exons. However, transcriptome-wide pairing within endogenous transcripts has not been examined for the prevalence of each mode in mammalian cells. Here we report such pairings in rat GH3 pituitary cells by measuring the relative abundance of nuclear RNA-Seq reads at the intron start or end (RISE). Interestingly, RISE indexes are positively correlated between 5′ and 3′ splice sites specifically across introns or exons but inversely correlated with the usage of adjacent exons. Moreover, the ratios between the paired indexes were globally modulated by depolarization, which was disruptible by 5-aza-Cytidine. The nucleotide matrices of the RISE-positive splice sites deviate significantly from the rat consensus, and short introns or exons are enriched with the cross-intron or -exon RISE pairs, respectively. Functionally, the RISE-positive genes cluster for basic cellular processes including RNA binding/splicing, or more specifically, hormone production if regulated by depolarization. Together, the RISE analysis identified the transcriptome-wide regulation of either intron or exon definition between weak splice sites of short introns/exons in mammalian cells. The analysis also provides a way to further track the splicing intermediates and intron/exon definition during the dynamic regulation of alternative splicing by extracellular factors.
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16
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Comprehensive analysis of the circadian nuclear and cytoplasmic transcriptome in mouse liver. PLoS Genet 2022; 18:e1009903. [PMID: 35921362 PMCID: PMC9377612 DOI: 10.1371/journal.pgen.1009903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 08/15/2022] [Accepted: 07/06/2022] [Indexed: 11/19/2022] Open
Abstract
In eukaryotes, RNA is synthesised in the nucleus, spliced, and exported to the cytoplasm where it is translated and finally degraded. Any of these steps could be subject to temporal regulation during the circadian cycle, resulting in daily fluctuations of RNA accumulation and affecting the distribution of transcripts in different subcellular compartments. Our study analysed the nuclear and cytoplasmic, poly(A) and total transcriptomes of mouse livers collected over the course of a day. These data provide a genome-wide temporal inventory of enrichment in subcellular RNA, and revealed specific signatures of splicing, nuclear export and cytoplasmic mRNA stability related to transcript and gene lengths. Combined with a mathematical model describing rhythmic RNA profiles, we could test the rhythmicity of export rates and cytoplasmic degradation rates of approximately 1400 genes. With nuclear export times usually much shorter than cytoplasmic half-lives, we found that nuclear export contributes to the modulation and generation of rhythmic profiles of 10% of the cycling nuclear mRNAs. This study contributes to a better understanding of the dynamic regulation of the transcriptome during the day-night cycle.
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17
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Pamudurti NR, Patop IL, Krishnamoorthy A, Bartok O, Maya R, Lerner N, Ashwall-Fluss R, Konakondla JVV, Beatus T, Kadener S. circMbl functions in cis and in trans to regulate gene expression and physiology in a tissue-specific fashion. Cell Rep 2022; 39:110740. [PMID: 35476987 PMCID: PMC9352392 DOI: 10.1016/j.celrep.2022.110740] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 02/11/2022] [Accepted: 04/05/2022] [Indexed: 11/03/2022] Open
Abstract
Muscleblind (mbl) is an essential muscle and neuronal splicing regulator. Mbl hosts multiple circular RNAs (circRNAs), including circMbl, which is conserved from flies to humans. Here, we show that mbl-derived circRNAs are key regulators of MBL by cis- and trans-acting mechanisms. By generating fly lines to specifically modulate the levels of all mbl RNA isoforms, including circMbl, we demonstrate that the two major mbl protein isoforms, MBL-O/P and MBL-C, buffer their own levels by producing different types of circRNA isoforms in the eye and fly brain, respectively. Moreover, we show that circMbl has unique functions in trans, as knockdown of circMbl results in specific morphological and physiological phenotypes. In addition, depletion of MBL-C or circMbl results in opposite behavioral phenotypes, showing that they also regulate each other in trans. Together, our results illuminate key aspects of mbl regulation and uncover cis and trans functions of circMbl in vivo.
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Affiliation(s)
| | | | | | - Osnat Bartok
- Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Roni Maya
- The Rachel and Selim Benin School of Computer Science and Engineering, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel; Department of Neurobiology, The Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Noam Lerner
- The Rachel and Selim Benin School of Computer Science and Engineering, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel; Department of Neurobiology, The Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Reut Ashwall-Fluss
- Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | | | - Tsevi Beatus
- The Rachel and Selim Benin School of Computer Science and Engineering, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel; Department of Neurobiology, The Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Sebastian Kadener
- Biology Department, Brandeis University, Waltham, MA 02454, USA; Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel.
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18
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Arthurs AL, Jankovic-Karasoulos T, Smith MD, Roberts CT. Circular RNAs in Pregnancy and the Placenta. Int J Mol Sci 2022; 23:ijms23094551. [PMID: 35562943 PMCID: PMC9100345 DOI: 10.3390/ijms23094551] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 04/16/2022] [Accepted: 04/19/2022] [Indexed: 01/27/2023] Open
Abstract
The emerging field of circular RNAs (circRNAs) has identified their novel roles in the development and function of many cancers and inspired the interest of many researchers. circRNAs are also found throughout the healthy body, as well as in other pathological states, but while research into the function and abundance of circRNAs has progressed, our overall understanding of these molecules remains primitive. Importantly, recent studies are elucidating new roles for circRNAs in pregnancy, particularly in the placenta. Given that many of the genes responsible for circRNA production in cancer are also highly expressed in the placenta, it is likely that the same genes act in the production of circRNAs in the placenta. Furthermore, placental development can be referred to as ‘controlled cancer’, as it shares many key signalling pathways and hallmarks with tumour growth and metastasis. Hence, the roles of circRNAs in this field are important to study with respect to pregnancy success but also may provide novel insights for cancer progression. This review illuminates the known roles of circRNAs in pregnancy and the placenta, as well as demonstrating differential placental expressions of circRNAs between complicated and uncomplicated pregnancies.
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19
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Co-transcriptional splicing efficiency is a gene-specific feature that can be regulated by TGFβ. Commun Biol 2022; 5:277. [PMID: 35347226 PMCID: PMC8960766 DOI: 10.1038/s42003-022-03224-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 03/03/2022] [Indexed: 11/26/2022] Open
Abstract
Differential splicing efficiency of specific introns is a mechanism that dramatically increases protein diversity, based on selection of alternative exons for the final mature mRNA. However, it is unclear whether splicing efficiency of introns within the same gene is coordinated and eventually regulated as a mechanism to control mature mRNA levels. Based on nascent chromatin-associated RNA-sequencing data, we now find that co-transcriptional splicing (CTS) efficiency tends to be similar between the different introns of a gene. We establish that two well-differentiated strategies for CTS efficiency exist, at the extremes of a gradient: short genes that produce high levels of pre-mRNA undergo inefficient splicing, while long genes with relatively low levels of pre-mRNA have an efficient splicing. Notably, we observe that genes with efficient CTS display a higher level of mature mRNA relative to their pre-mRNA levels. Further, we show that the TGFβ signal transduction pathway regulates the general CTS efficiency, causing changes in mature mRNA levels. Taken together, our data indicate that CTS efficiency is a gene-specific characteristic that can be regulated to control gene expression. Co-transcriptional splicing efficiency is a gene-specific characteristic that can be regulated by TGFβ to modulate gene expression.
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20
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Koks S, Pfaff AL, Bubb VJ, Quinn JP. Longitudinal intronic RNA-Seq analysis of Parkinson's disease patients reveals disease-specific nascent transcription. Exp Biol Med (Maywood) 2022; 247:945-957. [PMID: 35289213 DOI: 10.1177/15353702221081027] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Transcriptomic studies usually focus on either gene or exon-based annotations, and only limited experiments have reported changes in reads mapping to introns. The analysis of intronic reads allows the detection of nascent transcription that is not influenced by steady-state RNA levels and provides information on actively transcribed genes. Here, we describe substantial intronic transcriptional changes in Parkinson's disease (PD) patients compared to healthy controls (CO) at two different timepoints; at the time of diagnosis (BL) and three years later (V08). We used blood RNA-Seq data from the Parkinson's Progression Markers Initiative (PPMI) cohort and identified significantly changed transcription of intronic reads only in PD patients during this follow-up period. In CO subjects, only nine transcripts demonstrated differentially expressed introns between visits. However, in PD patients, 4873 transcripts had differentially expressed introns at visit V08 compared to BL, many of them in genes previously associated with neurodegenerative diseases, such as LRRK2, C9orf72, LGALS3, KANSL1AS1, and ALS2. In addition, at the time of diagnosis (BL visit), we identified 836 transcripts (e.g. SNCA, DNAJC19, PRRG4) and at visit V08, 2184 transcripts (e.g. PINK1, GBA, ALS2, PLEKHM1) with differential intronic expression specific to PD patients. In contrast, reads mapping to exonic regions demonstrated little variation indicating highly specific changes only in intronic transcription. Our study demonstrated that PD is characterized by substantial changes in the nascent transcription, and description of these changes could help to understand the molecular pathology underpinning this disease.
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Affiliation(s)
- Sulev Koks
- Perron Institute for Neurological and Translational Science, Perth, WA 6009, Australia.,Centre for Molecular Medicine and Innovative Therapeutics, Murdoch University, Perth, WA 6150, Australia
| | - Abigail L Pfaff
- Perron Institute for Neurological and Translational Science, Perth, WA 6009, Australia.,Centre for Molecular Medicine and Innovative Therapeutics, Murdoch University, Perth, WA 6150, Australia
| | - Vivien J Bubb
- Department of Pharmacology and Therapeutics, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool L69 3BX, UK
| | - John P Quinn
- Department of Pharmacology and Therapeutics, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool L69 3BX, UK
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21
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CMTr cap-adjacent 2'-O-ribose mRNA methyltransferases are required for reward learning and mRNA localization to synapses. Nat Commun 2022; 13:1209. [PMID: 35260552 PMCID: PMC8904806 DOI: 10.1038/s41467-022-28549-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 01/18/2022] [Indexed: 11/25/2022] Open
Abstract
Cap-adjacent nucleotides of animal, protist and viral mRNAs can be O-methylated at the 2‘ position of the ribose (cOMe). The functions of cOMe in animals, however, remain largely unknown. Here we show that the two cap methyltransferases (CMTr1 and CMTr2) of Drosophila can methylate the ribose of the first nucleotide in mRNA. Double-mutant flies lack cOMe but are viable. Consistent with prominent neuronal expression, they have a reward learning defect that can be rescued by conditional expression in mushroom body neurons before training. Among CMTr targets are cell adhesion and signaling molecules. Many are relevant for learning, and are also targets of Fragile X Mental Retardation Protein (FMRP). Like FMRP, cOMe is required for localization of untranslated mRNAs to synapses and enhances binding of the cap binding complex in the nucleus. Hence, our study reveals a mechanism to co-transcriptionally prime mRNAs by cOMe for localized protein synthesis at synapses. The two cap methyltransferases (CMTrs) redundantly methylate riboses of first cap adjacent nucleotides in messenger RNAs in Drosophila. Here, CMTrs are required for reward learning and localization of untranslated messenger RNAs to synapses.
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22
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Martinez NM, Su A, Burns MC, Nussbacher JK, Schaening C, Sathe S, Yeo GW, Gilbert WV. Pseudouridine synthases modify human pre-mRNA co-transcriptionally and affect pre-mRNA processing. Mol Cell 2022; 82:645-659.e9. [PMID: 35051350 PMCID: PMC8859966 DOI: 10.1016/j.molcel.2021.12.023] [Citation(s) in RCA: 74] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 11/04/2021] [Accepted: 12/17/2021] [Indexed: 02/05/2023]
Abstract
Pseudouridine is a modified nucleotide that is prevalent in human mRNAs and is dynamically regulated. Here, we investigate when in their life cycle mRNAs become pseudouridylated to illuminate the potential regulatory functions of endogenous mRNA pseudouridylation. Using single-nucleotide resolution pseudouridine profiling on chromatin-associated RNA from human cells, we identified pseudouridines in nascent pre-mRNA at locations associated with alternatively spliced regions, enriched near splice sites, and overlapping hundreds of binding sites for RNA-binding proteins. In vitro splicing assays establish a direct effect of individual endogenous pre-mRNA pseudouridines on splicing efficiency. We validate hundreds of pre-mRNA sites as direct targets of distinct pseudouridine synthases and show that PUS1, PUS7, and RPUSD4-three pre-mRNA-modifying pseudouridine synthases with tissue-specific expression-control widespread changes in alternative pre-mRNA splicing and 3' end processing. Our results establish a vast potential for cotranscriptional pre-mRNA pseudouridylation to regulate human gene expression via alternative pre-mRNA processing.
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Affiliation(s)
- Nicole M Martinez
- Yale School of Medicine, Department of Molecular Biophysics & Biochemistry, New Haven, CT 06520, USA
| | - Amanda Su
- Yale School of Medicine, Department of Molecular Biophysics & Biochemistry, New Haven, CT 06520, USA
| | - Margaret C Burns
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92037, USA; Stem Cell Program, University of California, San Diego, La Jolla, CA 92037, USA; Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA 92037, USA
| | - Julia K Nussbacher
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92037, USA; Stem Cell Program, University of California, San Diego, La Jolla, CA 92037, USA; Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA 92037, USA
| | - Cassandra Schaening
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Shashank Sathe
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92037, USA; Stem Cell Program, University of California, San Diego, La Jolla, CA 92037, USA; Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA 92037, USA
| | - Gene W Yeo
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92037, USA; Stem Cell Program, University of California, San Diego, La Jolla, CA 92037, USA; Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA 92037, USA.
| | - Wendy V Gilbert
- Yale School of Medicine, Department of Molecular Biophysics & Biochemistry, New Haven, CT 06520, USA.
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23
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Prudêncio P, Savisaar R, Rebelo K, Martinho RG, Carmo-Fonseca M. Transcription and splicing dynamics during early Drosophila development. RNA (NEW YORK, N.Y.) 2022; 28:139-161. [PMID: 34667107 PMCID: PMC8906543 DOI: 10.1261/rna.078933.121] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 09/23/2021] [Indexed: 05/03/2023]
Abstract
Widespread cotranscriptional splicing has been demonstrated from yeast to human. However, most studies to date addressing the kinetics of splicing relative to transcription used either Saccharomyces cerevisiae or metazoan cultured cell lines. Here, we adapted native elongating transcript sequencing technology (NET-seq) to measure cotranscriptional splicing dynamics during the early developmental stages of Drosophila melanogaster embryos. Our results reveal the position of RNA polymerase II (Pol II) when both canonical and recursive splicing occur. We found heterogeneity in splicing dynamics, with some RNAs spliced immediately after intron transcription, whereas for other transcripts no splicing was observed over the first 100 nt of the downstream exon. Introns that show splicing completion before Pol II has reached the end of the downstream exon are necessarily intron-defined. We studied the splicing dynamics of both nascent pre-mRNAs transcribed in the early embryo, which have few and short introns, as well as pre-mRNAs transcribed later in embryonic development, which contain multiple long introns. As expected, we found a relationship between the proportion of spliced reads and intron size. However, intron definition was observed at all intron sizes. We further observed that genes transcribed in the early embryo tend to be isolated in the genome whereas genes transcribed later are often overlapped by a neighboring convergent gene. In isolated genes, transcription termination occurred soon after the polyadenylation site, while in overlapped genes, Pol II persisted associated with the DNA template after cleavage and polyadenylation of the nascent transcript. Taken together, our data unravel novel dynamic features of Pol II transcription and splicing in the developing Drosophila embryo.
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Affiliation(s)
- Pedro Prudêncio
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
- Algarve Biomedical Center Research Institute (ABC-RI), Universidade do Algarve, 8005-139 Faro, Portugal
| | - Rosina Savisaar
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Kenny Rebelo
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Rui Gonçalo Martinho
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
- Algarve Biomedical Center Research Institute (ABC-RI), Universidade do Algarve, 8005-139 Faro, Portugal
- Department of Medical Sciences and Institute for Biomedicine (iBiMED), Universidade de Aveiro, 3810-193 Aveiro, Portugal
| | - Maria Carmo-Fonseca
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
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24
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Carnesecchi J, Boumpas P, van Nierop Y Sanchez P, Domsch K, Pinto HD, Borges Pinto P, Lohmann I. The Hox transcription factor Ultrabithorax binds RNA and regulates co-transcriptional splicing through an interplay with RNA polymerase II. Nucleic Acids Res 2021; 50:763-783. [PMID: 34931250 PMCID: PMC8789087 DOI: 10.1093/nar/gkab1250] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 12/01/2021] [Accepted: 12/07/2021] [Indexed: 11/13/2022] Open
Abstract
Transcription factors (TFs) play a pivotal role in cell fate decision by coordinating gene expression programs. Although most TFs act at the DNA layer, few TFs bind RNA and modulate splicing. Yet, the mechanistic cues underlying TFs activity in splicing remain elusive. Focusing on the Drosophila Hox TF Ultrabithorax (Ubx), our work shed light on a novel layer of Ubx function at the RNA level. Transcriptome and genome-wide binding profiles in embryonic mesoderm and Drosophila cells indicate that Ubx regulates mRNA expression and splicing to promote distinct outcomes in defined cellular contexts. Our results demonstrate a new RNA-binding ability of Ubx. We find that the N51 amino acid of the DNA-binding Homeodomain is non-essential for RNA interaction in vitro, but is required for RNA interaction in vivo and Ubx splicing activity. Moreover, mutation of the N51 amino acid weakens the interaction between Ubx and active RNA Polymerase II (Pol II). Our results reveal that Ubx regulates elongation-coupled splicing, which could be coordinated by a dynamic interplay with active Pol II on chromatin. Overall, our work uncovered a novel role of the Hox TFs at the mRNA regulatory layer. This could be an essential function for other classes of TFs to control cell diversity.
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Affiliation(s)
- Julie Carnesecchi
- Heidelberg University, Centre for Organismal Studies (COS) Heidelberg, Department of Developmental Biology, Heidelberg, Germany.,Institut de Génomique Fonctionnelle de Lyon, Université de Lyon, CNRS UMR5242, Ecole Normale Supérieure de Lyon, Lyon, France
| | - Panagiotis Boumpas
- Heidelberg University, Centre for Organismal Studies (COS) Heidelberg, Department of Developmental Biology, Heidelberg, Germany
| | - Patrick van Nierop Y Sanchez
- Heidelberg University, Centre for Organismal Studies (COS) Heidelberg, Department of Developmental Biology, Heidelberg, Germany
| | - Katrin Domsch
- Heidelberg University, Centre for Organismal Studies (COS) Heidelberg, Department of Developmental Biology, Heidelberg, Germany.,Friedrich-Alexander-University Erlangen-Nürnberg, Department Biology, Division of Developmental Biology, Erlangen, Germany
| | - Hugo Daniel Pinto
- Department of Cell Biology, Albert Einstein College of Medicine, New York, NY, USA
| | - Pedro Borges Pinto
- Heidelberg University, Centre for Organismal Studies (COS) Heidelberg, Department of Developmental Biology, Heidelberg, Germany.,Institut de Génomique Fonctionnelle de Lyon, Université de Lyon, CNRS UMR5242, Ecole Normale Supérieure de Lyon, Lyon, France
| | - Ingrid Lohmann
- Heidelberg University, Centre for Organismal Studies (COS) Heidelberg, Department of Developmental Biology, Heidelberg, Germany
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25
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Krishnamoorthy A, Kadener S. Using Drosophila to uncover molecular and physiological functions of circRNAs. Methods 2021; 196:74-84. [PMID: 33901645 PMCID: PMC8542058 DOI: 10.1016/j.ymeth.2021.04.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 04/16/2021] [Accepted: 04/21/2021] [Indexed: 11/17/2022] Open
Abstract
Circular RNAs (circRNAs) are a class of covalently closed RNA molecules generated by backsplicing. circRNAs are expressed in a tissue-specific manner, accumulate with age in neural tissues, and are highly stable. In many cases, circRNAs are generated at the expense of a linear transcript as back-splicing competes with linear splicing. Some circRNAs regulate gene expression in cis, and some circRNAs can be translated into protein. The advent of deep sequencing and new bioinformatic tools has allowed detection of thousands of circRNAs in eukaryotes. Studying the functions of circRNAs is done using a combination of molecular and genetic methods. The unique genetic tools that can be used in studies of Drosophila melanogaster are ideal for deciphering the functions of circRNAs in vivo. These tools include the GAL4-UAS system, which can be used to manipulate the levels of circRNAs with exquisite temporal and spatial control, and genetic interaction screening, which could be used to identify pathways regulated by circRNAs. Research performed in Drosophila has revealed circRNAs production mechanisms, details of their translation, and their physiological functions. Due to their short lifecycle and the existence of excellent neurodegeneration models, Drosophila can also be used to study the role of circRNAs in aging and age-related disorders. Here, we review molecular and genetic tools and methods for detecting, manipulating, and studying circRNAs in Drosophila.
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Affiliation(s)
| | - Sebastian Kadener
- Biology Department, Brandeis University, Waltham, MA 02454, United States.
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26
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Tao M, Zheng M, Xu Y, Ma S, Zhang W, Ju S. CircRNAs and their regulatory roles in cancers. Mol Med 2021; 27:94. [PMID: 34445958 PMCID: PMC8393742 DOI: 10.1186/s10020-021-00359-3] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2021] [Accepted: 08/18/2021] [Indexed: 01/17/2023] Open
Abstract
Circular RNAs (circRNAs), a novel type of non-coding RNAs (ncRNAs), have a covalently closed circular structure resulting from pre-mRNA back splicing via spliceosome and ribozymes. They can be classified differently in accordance with different criteria. As circRNAs are abundant, conserved, and stable, they can be used as diagnostic markers in various diseases and targets to develop new therapies. There are various functions of circRNAs, including sponge for miR/proteins, role of scaffolds, templates for translation, and regulators of mRNA translation and stability. Without m7G cap and poly-A tail, circRNAs can still be degraded in several ways, including RNase L, Ago-dependent, and Ago-independent degradation. Increasing evidence indicates that circRNAs can be modified by N-6 methylation (m6A) in many aspects such as biogenesis, nuclear export, translation, and degradation. In addition, they have been proved to play a regulatory role in the progression of various cancers. Recently, methods of detecting circRNAs with high sensitivity and specificity have also been reported. This review presents a detailed overview of circRNAs regarding biogenesis, biomarker, functions, degradation, and dynamic modification as well as their regulatory roles in various cancers. It’s particularly summarized in detail in the biogenesis of circRNAs, regulation of circRNAs by m6A modification and mechanisms by which circRNAs affect tumor progression respectively. Moreover, existing circRNA detection methods and their characteristics are also mentioned.
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Affiliation(s)
- Mei Tao
- Department of Laboratory Medicine, Affiliated Hospital of Nantong University, Xisi Road, No.20, Nantong, 226001, Jiangsu, China.,Research Center of Clinical Medicine, Affiliated Hospital of Nantong University, Nantong, 226001, Jiangsu, China.,Medical School of Nantong University, Nantong University, Nantong, 226001, Jiangsu, China
| | - Ming Zheng
- Department of Laboratory Medicine, Affiliated Hospital of Nantong University, Xisi Road, No.20, Nantong, 226001, Jiangsu, China.,Research Center of Clinical Medicine, Affiliated Hospital of Nantong University, Nantong, 226001, Jiangsu, China.,Medical School of Nantong University, Nantong University, Nantong, 226001, Jiangsu, China
| | - Yanhua Xu
- Department of Laboratory Medicine, Affiliated Hospital of Nantong University, Xisi Road, No.20, Nantong, 226001, Jiangsu, China.,Research Center of Clinical Medicine, Affiliated Hospital of Nantong University, Nantong, 226001, Jiangsu, China.,Medical School of Nantong University, Nantong University, Nantong, 226001, Jiangsu, China
| | - Shuo Ma
- Department of Laboratory Medicine, Affiliated Hospital of Nantong University, Xisi Road, No.20, Nantong, 226001, Jiangsu, China.,Research Center of Clinical Medicine, Affiliated Hospital of Nantong University, Nantong, 226001, Jiangsu, China.,Medical School of Nantong University, Nantong University, Nantong, 226001, Jiangsu, China
| | - Weiwei Zhang
- Department of Laboratory Medicine, Affiliated Hospital of Nantong University, Xisi Road, No.20, Nantong, 226001, Jiangsu, China. .,Research Center of Clinical Medicine, Affiliated Hospital of Nantong University, Nantong, 226001, Jiangsu, China.
| | - Shaoqing Ju
- Department of Laboratory Medicine, Affiliated Hospital of Nantong University, Xisi Road, No.20, Nantong, 226001, Jiangsu, China.
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27
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Muniz L, Nicolas E, Trouche D. RNA polymerase II speed: a key player in controlling and adapting transcriptome composition. EMBO J 2021; 40:e105740. [PMID: 34254686 PMCID: PMC8327950 DOI: 10.15252/embj.2020105740] [Citation(s) in RCA: 72] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 05/01/2021] [Accepted: 05/10/2021] [Indexed: 12/19/2022] Open
Abstract
RNA polymerase II (RNA Pol II) speed or elongation rate, i.e., the number of nucleotides synthesized per unit of time, is a major determinant of transcriptome composition. It controls co-transcriptional processes such as splicing, polyadenylation, and transcription termination, thus regulating the production of alternative splice variants, circular RNAs, alternatively polyadenylated transcripts, or read-through transcripts. RNA Pol II speed itself is regulated in response to intra- and extra-cellular stimuli and can in turn affect the transcriptome composition in response to these stimuli. Evidence points to a potentially important role of transcriptome composition modification through RNA Pol II speed regulation for adaptation of cells to a changing environment, thus pointing to a function of RNA Pol II speed regulation in cellular physiology. Analyzing RNA Pol II speed dynamics may therefore be central to fully understand the regulation of physiological processes, such as the development of multicellular organisms. Recent findings also raise the possibility that RNA Pol II speed deregulation can be detrimental and participate in disease progression. Here, we review initial and current approaches to measure RNA Pol II speed, as well as providing an overview of the factors controlling speed and the co-transcriptional processes which are affected. Finally, we discuss the role of RNA Pol II speed regulation in cell physiology.
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Affiliation(s)
- Lisa Muniz
- MCDCentre de Biologie Integrative (CBI)CNRSUPSUniversity of ToulouseToulouseFrance
| | - Estelle Nicolas
- MCDCentre de Biologie Integrative (CBI)CNRSUPSUniversity of ToulouseToulouseFrance
| | - Didier Trouche
- MCDCentre de Biologie Integrative (CBI)CNRSUPSUniversity of ToulouseToulouseFrance
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28
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Challenges and Opportunities in Understanding Genetics of Fungal Diseases: Towards a Functional Genomics Approach. Infect Immun 2021; 89:e0000521. [PMID: 34031131 DOI: 10.1128/iai.00005-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Infectious diseases are a leading cause of morbidity and mortality worldwide, and human pathogens have long been recognized as one of the main sources of evolutionary pressure, resulting in a high variable genetic background in immune-related genes. The study of the genetic contribution to infectious diseases has undergone tremendous advances over the last decades. Here, focusing on genetic predisposition to fungal diseases, we provide an overview of the available approaches for studying human genetic susceptibility to infections, reviewing current methodological and practical limitations. We describe how the classical methods available, such as family-based studies and candidate gene studies, have contributed to the discovery of crucial susceptibility factors for fungal infections. We will also discuss the contribution of novel unbiased approaches to the field, highlighting their success but also their limitations for the fungal immunology field. Finally, we show how a systems genomics approach can overcome those limitations and can lead to efficient prioritization and identification of genes and pathways with a critical role in susceptibility to fungal diseases. This knowledge will help to stratify at-risk patient groups and, subsequently, develop early appropriate prophylactic and treatment strategies.
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29
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de Melo Costa VR, Pfeuffer J, Louloupi A, Ørom UAV, Piro RM. SPLICE-q: a Python tool for genome-wide quantification of splicing efficiency. BMC Bioinformatics 2021; 22:368. [PMID: 34266387 PMCID: PMC8281633 DOI: 10.1186/s12859-021-04282-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 07/06/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Introns are generally removed from primary transcripts to form mature RNA molecules in a post-transcriptional process called splicing. An efficient splicing of primary transcripts is an essential step in gene expression and its misregulation is related to numerous human diseases. Thus, to better understand the dynamics of this process and the perturbations that might be caused by aberrant transcript processing it is important to quantify splicing efficiency. RESULTS Here, we introduce SPLICE-q, a fast and user-friendly Python tool for genome-wide SPLICing Efficiency quantification. It supports studies focusing on the implications of splicing efficiency in transcript processing dynamics. SPLICE-q uses aligned reads from strand-specific RNA-seq to quantify splicing efficiency for each intron individually and allows the user to select different levels of restrictiveness concerning the introns' overlap with other genomic elements such as exons of other genes. We applied SPLICE-q to globally assess the dynamics of intron excision in yeast and human nascent RNA-seq. We also show its application using total RNA-seq from a patient-matched prostate cancer sample. CONCLUSIONS Our analyses illustrate that SPLICE-q is suitable to detect a progressive increase of splicing efficiency throughout a time course of nascent RNA-seq and it might be useful when it comes to understanding cancer progression beyond mere gene expression levels. SPLICE-q is available at: https://github.com/vrmelo/SPLICE-q.
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Affiliation(s)
- Verônica R de Melo Costa
- Institute of Computer Science and Institute of Bioinformatics, Freie Universität Berlin, Berlin, Germany.
- Department of Computational Molecular Biology, Max Planck Institute for Molecular Genetics, Berlin, Germany.
| | - Julianus Pfeuffer
- Institute of Computer Science and Institute of Bioinformatics, Freie Universität Berlin, Berlin, Germany
- Department of Computer Science, Eberhard Karls Universität Tübingen, Tübingen, Germany
- Institute for Bioinformatics and Medical Informatics Tübingen, Eberhard Karls Universität Tübingen, Tübingen, Germany
| | - Annita Louloupi
- Max Delbrück Center for Molecular Medicine, Berlin Institute for Medical Systems Biology, Berlin, Germany
| | - Ulf A V Ørom
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Rosario M Piro
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milan, Italy.
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30
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Ptok J, Müller L, Ostermann PN, Ritchie A, Dilthey AT, Theiss S, Schaal H. Modifying splice site usage with ModCon: Maintaining the genetic code while changing the underlying mRNP code. Comput Struct Biotechnol J 2021; 19:3069-3076. [PMID: 34136105 PMCID: PMC8178101 DOI: 10.1016/j.csbj.2021.05.033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 05/14/2021] [Accepted: 05/20/2021] [Indexed: 11/22/2022] Open
Abstract
Codon degeneracy of amino acid sequences permits an additional “mRNP code” layer underlying the genetic code that is related to RNA processing. In pre-mRNA splicing, splice site usage is determined by both intrinsic strength and sequence context providing RNA binding sites for splicing regulatory proteins. In this study, we systematically examined modification of splicing regulatory properties in the neighborhood of a GT site, i.e. potential splice site, without altering the encoded amino acids. We quantified the splicing regulatory properties of the neighborhood around a potential splice site by its Splice Site HEXplorer Weight (SSHW) based on the HEXplorer score algorithm. To systematically modify GT site neighborhoods, either minimizing or maximizing their SSHW, we designed the novel stochastic optimization algorithm ModCon that applies a genetic algorithm with stochastic crossover, insertion and random mutation elements supplemented by a heuristic sliding window approach. To assess the achievable range in SSHW in human splice donors without altering the encoded amino acids, we applied ModCon to a set of 1000 randomly selected Ensembl annotated human splice donor sites, achieving substantial and accurate changes in SSHW. Using ModCon optimization, we successfully switched splice donor usage in a splice site competition reporter containing coding sequences from FANCA, FANCB or BRCA2, while retaining their amino acid coding information. The ModCon algorithm and its R package implementation can assist in reporter design by either introducing novel splice sites, silencing accidental, undesired splice sites, and by generally modifying the entire mRNP code while maintaining the genetic code.
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Key Words
- A, adenine
- F1, filial sequence 1
- G, guanine
- GA, genetic algorithm
- HBS, HBond score
- HBond score
- HEXplorer score
- HZEI, HEXplorer score
- P1, parental sequence 1
- SA, splice acceptor
- SD, splice donor
- SR proteins, serine- and arginine-rich proteins
- SRP, splicing regulatory protein
- SSHW, splice site HEXplorer weight
- SW, sliding window
- Splice donor
- Splicing regulatory proteins
- Splicing reporter
- T, thymine
- eGFP, enhanced green fluorescent protein
- hnRNP, heterogeneous nuclear ribonucleoproteins
- nt, nucleotides
- pre-mRNA splicing
- pre-mRNA, precursor messenger RNA
- snRNA, small nuclear RNA
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Affiliation(s)
- Johannes Ptok
- Institute of Virology, Medical Faculty, Heinrich Heine University Düsseldorf, D-40225 Düsseldorf, Germany
| | - Lisa Müller
- Institute of Virology, Medical Faculty, Heinrich Heine University Düsseldorf, D-40225 Düsseldorf, Germany
| | - Philipp Niklas Ostermann
- Institute of Virology, Medical Faculty, Heinrich Heine University Düsseldorf, D-40225 Düsseldorf, Germany
| | - Anastasia Ritchie
- Institute of Virology, Medical Faculty, Heinrich Heine University Düsseldorf, D-40225 Düsseldorf, Germany
| | - Alexander T Dilthey
- Institute of Medical Statistics and Computational Biology, University of Cologne, Cologne, Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
- Institute of Medical Microbiology and Hospital Hygiene, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Stephan Theiss
- Institute of Virology, Medical Faculty, Heinrich Heine University Düsseldorf, D-40225 Düsseldorf, Germany
| | - Heiner Schaal
- Institute of Virology, Medical Faculty, Heinrich Heine University Düsseldorf, D-40225 Düsseldorf, Germany
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31
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Bedi K, Magnuson BR, Narayanan I, Paulsen M, Wilson TE, Ljungman M. Co-transcriptional splicing efficiencies differ within genes and between cell types. RNA (NEW YORK, N.Y.) 2021; 27:rna.078662.120. [PMID: 33975916 PMCID: PMC8208053 DOI: 10.1261/rna.078662.120] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Accepted: 05/05/2021] [Indexed: 06/01/2023]
Abstract
Pre-mRNA splicing is carried out by the spliceosome and involves splice site recognition, removal of introns, and ligation of exons. Components of the spliceosome have been shown to interact with the elongating RNA polymerase II (RNAPII) which is thought to allow splicing to occur concurrently with transcription. However, little is known about the regulation and efficiency of co-transcriptional splicing in human cells. In this study, we used Bru-seq and BruChase-seq to determine the co-transcriptional splicing efficiencies of 17,000 introns expressed across 6 human cell lines. We found that less than half of all introns across these 6 cell lines were co-transcriptionally spliced. Splicing efficiencies for individual introns showed variations across cell lines, suggesting that splicing may be regulated in a cell-type specific manner. Moreover, the splicing efficiency of introns varied within genes. The efficiency of co-transcriptional splicing did not correlate with gene length, intron position, splice site strengths, or the intron/neighboring exons GC content. However, we identified binding signals from multiple RNA binding proteins (RBPs) that correlated with splicing efficiency, including core spliceosomal machinery components-such as SF3B4, U2AF1 and U2AF2 showing higher binding signals in poorly spliced introns. In addition, multiple RBPs, such as BUD13, PUM1 and SND1, showed preferential binding in exons that flank introns with high splicing efficiencies. The nascent RNA splicing patterns presented here across multiple cell types add to our understanding of the complexity in RNA splicing, wherein RNA-binding proteins may play important roles in determining splicing outcomes in a cell type- and intron-specific manner.
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32
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Joseph B, Lai EC. The Exon Junction Complex and intron removal prevent re-splicing of mRNA. PLoS Genet 2021; 17:e1009563. [PMID: 34033644 PMCID: PMC8184009 DOI: 10.1371/journal.pgen.1009563] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 06/07/2021] [Accepted: 04/26/2021] [Indexed: 01/23/2023] Open
Abstract
Accurate splice site selection is critical for fruitful gene expression. Recently, the mammalian EJC was shown to repress competing, cryptic, splice sites (SS). However, the evolutionary generality of this remains unclear. Here, we demonstrate the Drosophila EJC suppresses hundreds of functional cryptic SS, even though most bear weak splicing motifs and are seemingly incompetent. Mechanistically, the EJC directly conceals cryptic splicing elements by virtue of its position-specific recruitment, preventing aberrant SS definition. Unexpectedly, we discover the EJC inhibits scores of regenerated 5' and 3' recursive SS on segments that have already undergone splicing, and that loss of EJC regulation triggers faulty resplicing of mRNA. An important corollary is that certain intronless cDNA constructs yield unanticipated, truncated transcripts generated by resplicing. We conclude the EJC has conserved roles to defend transcriptome fidelity by (1) repressing illegitimate splice sites on pre-mRNAs, and (2) preventing inadvertent activation of such sites on spliced segments.
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Affiliation(s)
- Brian Joseph
- Developmental Biology Program, Sloan Kettering Institute, New York, New York, United States of America
- Louis V. Gerstner, Jr. Graduate School of Biomedical Sciences, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
| | - Eric C. Lai
- Developmental Biology Program, Sloan Kettering Institute, New York, New York, United States of America
- Louis V. Gerstner, Jr. Graduate School of Biomedical Sciences, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
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33
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Conboy JG. Unannotated splicing regulatory elements in deep intron space. WILEY INTERDISCIPLINARY REVIEWS-RNA 2021; 12:e1656. [PMID: 33887804 DOI: 10.1002/wrna.1656] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 03/14/2021] [Accepted: 03/23/2021] [Indexed: 12/21/2022]
Abstract
Deep intron space harbors a diverse array of splicing regulatory elements that cooperate with better-known exon-proximal elements to enforce proper tissue-specific and development-specific pre-mRNA processing. Many deep intron elements have been highly conserved through vertebrate evolution, yet remain poorly annotated in the human genome. Recursive splicing exons (RS-exons) and intraexons promote noncanonical, multistep resplicing pathways in long introns, involving transient intermediate structures that are greatly underrepresented in RNA-seq datasets. Decoy splice sites and decoy exons act at a distance to inhibit splicing catalysis at annotated splice sites, with functional consequences such as exon skipping and intron retention. RNA:RNA bridges can juxtapose distant sequences within or across introns to activate deep intron splicing enhancers and silencers, to loop out exons to be skipped, or to select one member of a mutually exclusive set of exons. Similarly, protein bridges mediated by interactions among transcript-bound RNA binding proteins (RBPs) can modulate splicing outcomes. Experimental disruption of deep intron elements serving any of these functions can abrogate normal splicing, strongly suggesting that natural mutations of deep intron elements can do likewise to cause human disease. Understanding noncanonical splicing pathways and discovering deep intron regulatory signals, many of which map hundreds to many thousands of nucleotides from annotated splice junctions, is of great academic interest for basic scientists studying alternative splicing mechanisms. Hopefully, this knowledge coupled with increased analysis of deep intron sequences will also have important medical applications, as better interpretation of deep intron mutations may reveal new disease mechanisms and suggest new therapies. This article is categorized under: RNA Processing > Splicing Regulation/Alternative Splicing.
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Affiliation(s)
- John G Conboy
- Lawrence Berkeley National Laboratory, Biological Systems and Engineering Division, Berkeley, California, USA
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34
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Ng AYE, Pek JW. Circular sisRNA identification and characterisation. Methods 2021; 196:138-146. [PMID: 33838268 DOI: 10.1016/j.ymeth.2021.04.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Revised: 03/30/2021] [Accepted: 04/02/2021] [Indexed: 01/22/2023] Open
Abstract
Stable Intronic Sequence RNA (sisRNA) is a relatively new class of non-coding RNA. Found in many organisms, these sisRNA produced from their host genes are generally involved in regulatory roles, controlling gene expression at multiple levels through active involvement in regulatory feedback loops. Large scale identification of sisRNA via genome-wide RNA sequencing has been difficult, largely in part due to its low abundance. Done on its own, RNA sequencing often yields a large mass of information that is ironically uninformative; the potential sisRNA reads being masked by other highly abundant RNA species like ribosomal RNA and messenger RNA. In this review, we present a practical workflow for the enrichment of circular sisRNA through the use of transcriptionally quiescent systems, rRNA-depletion, and RNase R treatment prior to deep sequencing. This workflow allows circular sisRNA to be reliably detected. We also present various methods to experimentally validate the circularity and stability of the circular sisRNA identified, as well as a few methods for further functional characterisation.
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Affiliation(s)
- Amanda Yunn Ee Ng
- Temasek Life Sciences Laboratory, 1 Research Link National University of Singapore, Singapore 117604, Singapore; Department of Biological Sciences, National University of Singapore, 14 Science Drive, Singapore 117543, Singapore
| | - Jun Wei Pek
- Temasek Life Sciences Laboratory, 1 Research Link National University of Singapore, Singapore 117604, Singapore; Department of Biological Sciences, National University of Singapore, 14 Science Drive, Singapore 117543, Singapore.
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35
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Lee S, Wei L, Zhang B, Goering R, Majumdar S, Wen J, Taliaferro JM, Lai EC. ELAV/Hu RNA binding proteins determine multiple programs of neural alternative splicing. PLoS Genet 2021; 17:e1009439. [PMID: 33826609 PMCID: PMC8055025 DOI: 10.1371/journal.pgen.1009439] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 04/19/2021] [Accepted: 02/22/2021] [Indexed: 12/15/2022] Open
Abstract
ELAV/Hu factors are conserved RNA binding proteins (RBPs) that play diverse roles in mRNA processing and regulation. The founding member, Drosophila Elav, was recognized as a vital neural factor 35 years ago. Nevertheless, little was known about its impacts on the transcriptome, and potential functional overlap with its paralogs. Building on our recent findings that neural-specific lengthened 3' UTR isoforms are co-determined by ELAV/Hu factors, we address their impacts on splicing. While only a few splicing targets of Drosophila are known, ectopic expression of each of the three family members (Elav, Fne and Rbp9) alters hundreds of cassette exon and alternative last exon (ALE) splicing choices. Reciprocally, double mutants of elav/fne, but not elav alone, exhibit opposite effects on both classes of regulated mRNA processing events in larval CNS. While manipulation of Drosophila ELAV/Hu RBPs induces both exon skipping and inclusion, characteristic ELAV/Hu motifs are enriched only within introns flanking exons that are suppressed by ELAV/Hu factors. Moreover, the roles of ELAV/Hu factors in global promotion of distal ALE splicing are mechanistically linked to terminal 3' UTR extensions in neurons, since both processes involve bypass of proximal polyadenylation signals linked to ELAV/Hu motifs downstream of cleavage sites. We corroborate the direct action of Elav in diverse modes of mRNA processing using RRM-dependent Elav-CLIP data from S2 cells. Finally, we provide evidence for conservation in mammalian neurons, which undergo broad programs of distal ALE and APA lengthening, linked to ELAV/Hu motifs downstream of regulated polyadenylation sites. Overall, ELAV/Hu RBPs orchestrate multiple broad programs of neuronal mRNA processing and isoform diversification in Drosophila and mammalian neurons.
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Affiliation(s)
- Seungjae Lee
- Developmental Biology Program, Sloan Kettering Institute, New York City, New York, United States of America
| | - Lu Wei
- Developmental Biology Program, Sloan Kettering Institute, New York City, New York, United States of America
| | - Binglong Zhang
- Developmental Biology Program, Sloan Kettering Institute, New York City, New York, United States of America
| | - Raeann Goering
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
- RNA Bioscience Initiative University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Sonali Majumdar
- Developmental Biology Program, Sloan Kettering Institute, New York City, New York, United States of America
| | - Jiayu Wen
- Department of Genome Sciences, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - J. Matthew Taliaferro
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
- RNA Bioscience Initiative University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Eric C. Lai
- Developmental Biology Program, Sloan Kettering Institute, New York City, New York, United States of America
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36
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Mishra A, Siwach P, Misra P, Dhiman S, Pandey AK, Srivastava P, Jayaram B. Intron exon boundary junctions in human genome have in-built unique structural and energetic signals. Nucleic Acids Res 2021; 49:2674-2683. [PMID: 33621338 PMCID: PMC7969029 DOI: 10.1093/nar/gkab098] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2019] [Revised: 01/21/2021] [Accepted: 02/22/2021] [Indexed: 11/13/2022] Open
Abstract
Precise identification of correct exon–intron boundaries is a prerequisite to analyze the location and structure of genes. The existing framework for genomic signals, delineating exon and introns in a genomic segment, seems insufficient, predominantly due to poor sequence consensus as well as limitations of training on available experimental data sets. We present here a novel concept for characterizing exon–intron boundaries in genomic segments on the basis of structural and energetic properties. We analyzed boundary junctions on both sides of all the exons (3 28 368) of protein coding genes from human genome (GENCODE database) using 28 structural and three energy parameters. Study of sequence conservation at these sites shows very poor consensus. It is observed that DNA adopts a unique structural and energy state at the boundary junctions. Also, signals are somewhat different for housekeeping and tissue specific genes. Clustering of 31 parameters into four derived vectors gives some additional insights into the physical mechanisms involved in this biological process. Sites of structural and energy signals correlate well to the positions playing important roles in pre-mRNA splicing.
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Affiliation(s)
- Akhilesh Mishra
- Supercomputing Facility for Bioinformatics & Computational Biology, Indian Institute of Technology Delhi, India.,Kusuma School of Biological Sciences, Indian Institute of Technology, Delhi, India
| | - Priyanka Siwach
- Supercomputing Facility for Bioinformatics & Computational Biology, Indian Institute of Technology Delhi, India.,Department of Biotechnology, Chaudhary Devi Lal University, Sirsa, Haryana, India
| | - Pallavi Misra
- Supercomputing Facility for Bioinformatics & Computational Biology, Indian Institute of Technology Delhi, India
| | - Simran Dhiman
- Supercomputing Facility for Bioinformatics & Computational Biology, Indian Institute of Technology Delhi, India
| | | | - Parul Srivastava
- Supercomputing Facility for Bioinformatics & Computational Biology, Indian Institute of Technology Delhi, India
| | - B Jayaram
- Supercomputing Facility for Bioinformatics & Computational Biology, Indian Institute of Technology Delhi, India.,Kusuma School of Biological Sciences, Indian Institute of Technology, Delhi, India.,Department of Chemistry, Indian Institute of Technology, Delhi, India
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37
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Saldi T, Riemondy K, Erickson B, Bentley DL. Alternative RNA structures formed during transcription depend on elongation rate and modify RNA processing. Mol Cell 2021; 81:1789-1801.e5. [PMID: 33631106 DOI: 10.1016/j.molcel.2021.01.040] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 01/26/2021] [Accepted: 01/27/2021] [Indexed: 12/24/2022]
Abstract
Most RNA processing occurs co-transcriptionally. We interrogated nascent pol II transcripts by chemical and enzymatic probing and determined how the "nascent RNA structureome" relates to splicing, A-I editing and transcription speed. RNA folding within introns and steep structural transitions at splice sites are associated with efficient co-transcriptional splicing. A slow pol II mutant elicits extensive remodeling into more folded conformations with increased A-I editing. Introns that become more structured at their 3' splice sites get co-transcriptionally excised more efficiently. Slow pol II altered folding of intronic Alu elements where cryptic splicing and intron retention are stimulated, an outcome mimicked by UV, which decelerates transcription. Slow transcription also remodeled RNA folding around alternative exons in distinct ways that predict whether skipping or inclusion is favored, even though it occurs post-transcriptionally. Hence, co-transcriptional RNA folding modulates post-transcriptional alternative splicing. In summary, the plasticity of nascent transcripts has widespread effects on RNA processing.
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Affiliation(s)
- Tassa Saldi
- RNA Bioscience Initiative, Department Biochemistry and Molecular Genetics, University of Colorado School of Medicine, PO Box 6511, Aurora, CO 80045, USA
| | - Kent Riemondy
- RNA Bioscience Initiative, Department Biochemistry and Molecular Genetics, University of Colorado School of Medicine, PO Box 6511, Aurora, CO 80045, USA
| | - Benjamin Erickson
- RNA Bioscience Initiative, Department Biochemistry and Molecular Genetics, University of Colorado School of Medicine, PO Box 6511, Aurora, CO 80045, USA
| | - David L Bentley
- RNA Bioscience Initiative, Department Biochemistry and Molecular Genetics, University of Colorado School of Medicine, PO Box 6511, Aurora, CO 80045, USA.
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38
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Mertes C, Scheller IF, Yépez VA, Çelik MH, Liang Y, Kremer LS, Gusic M, Prokisch H, Gagneur J. Detection of aberrant splicing events in RNA-seq data using FRASER. Nat Commun 2021; 12:529. [PMID: 33483494 PMCID: PMC7822922 DOI: 10.1038/s41467-020-20573-7] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 12/07/2020] [Indexed: 12/28/2022] Open
Abstract
Aberrant splicing is a major cause of rare diseases. However, its prediction from genome sequence alone remains in most cases inconclusive. Recently, RNA sequencing has proven to be an effective complementary avenue to detect aberrant splicing. Here, we develop FRASER, an algorithm to detect aberrant splicing from RNA sequencing data. Unlike existing methods, FRASER captures not only alternative splicing but also intron retention events. This typically doubles the number of detected aberrant events and identified a pathogenic intron retention in MCOLN1 causing mucolipidosis. FRASER automatically controls for latent confounders, which are widespread and affect sensitivity substantially. Moreover, FRASER is based on a count distribution and multiple testing correction, thus reducing the number of calls by two orders of magnitude over commonly applied z score cutoffs, with a minor loss of sensitivity. Applying FRASER to rare disease diagnostics is demonstrated by reprioritizing a pathogenic aberrant exon truncation in TAZ from a published dataset. FRASER is easy to use and freely available.
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Affiliation(s)
- Christian Mertes
- Department of Informatics, Technical University of Munich, Garching, Germany
| | - Ines F Scheller
- Department of Informatics, Technical University of Munich, Garching, Germany
- Institute of Computational Biology, Helmholtz Zentrum München, Neuherberg, Germany
| | - Vicente A Yépez
- Department of Informatics, Technical University of Munich, Garching, Germany
- Quantitative Biosciences Munich, Gene Center, Ludwig-Maximilians Universität München, Munich, Germany
| | - Muhammed H Çelik
- Department of Informatics, Technical University of Munich, Garching, Germany
| | - Yingjiqiong Liang
- Department of Informatics, Technical University of Munich, Garching, Germany
| | - Laura S Kremer
- Institute of Human Genetics, Helmholtz Zentrum München, Neuherberg, Germany
- Institute of Human Genetics, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Mirjana Gusic
- Institute of Human Genetics, Helmholtz Zentrum München, Neuherberg, Germany
- Institute of Human Genetics, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Holger Prokisch
- Institute of Human Genetics, Helmholtz Zentrum München, Neuherberg, Germany
- Institute of Human Genetics, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Julien Gagneur
- Department of Informatics, Technical University of Munich, Garching, Germany.
- Institute of Computational Biology, Helmholtz Zentrum München, Neuherberg, Germany.
- Institute of Human Genetics, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany.
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39
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Zhu J, Zhao H, Kong F, Liu B, Liu M, Dong Z. Cotranscriptional and Posttranscriptional Features of the Transcriptome in Soybean Shoot Apex and Leaf. FRONTIERS IN PLANT SCIENCE 2021; 12:649634. [PMID: 33897737 PMCID: PMC8063115 DOI: 10.3389/fpls.2021.649634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Accepted: 03/02/2021] [Indexed: 05/13/2023]
Abstract
Transcription is the first step of central dogma, in which the genetic information stored in DNA is copied into RNA. In addition to mature RNA sequencing (RNA-seq), high-throughput nascent RNA assays have been established and applied to provide detailed transcriptional information. Here, we present the profiling of nascent RNA from trifoliate leaves and shoot apices of soybean. In combination with nascent RNA (chromatin-bound RNA, CB RNA) and RNA-seq, we found that introns were largely spliced cotranscriptionally. Although alternative splicing (AS) was mainly determined at nascent RNA biogenesis, differential AS between the leaf and shoot apex at the mature RNA level did not correlate well with cotranscriptional differential AS. Overall, RNA abundance was moderately correlated between nascent RNA and mature RNA within each tissue, but the fold changes between the leaf and shoot apex were highly correlated. Thousands of novel transcripts (mainly non-coding RNA) were detected by CB RNA-seq, including the overlap of natural antisense RNA with two important genes controlling soybean reproductive development, FT2a and Dt1. Taken together, we demonstrated the adoption of CB RNA-seq in soybean, which may shed light on gene expression regulation of important agronomic traits in leguminous crops.
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Affiliation(s)
- Jiafu Zhu
- Guangzhou Key Laboratory of Crop Gene Editing, Innovative Center of Molecular Genetics and Evolution, School of Life Sciences, Guangzhou Higher Education Mega Center, Guangzhou University, Guangzhou, China
| | - Han Zhao
- Provincial Key Laboratory of Agrobiology, Institute of Crop Germplasm and Biotechnology, Jiangsu Academy of Agricultural Sciences, Nanjing, China
| | - Fanjiang Kong
- Guangzhou Key Laboratory of Crop Gene Editing, Innovative Center of Molecular Genetics and Evolution, School of Life Sciences, Guangzhou Higher Education Mega Center, Guangzhou University, Guangzhou, China
| | - Baohui Liu
- Guangzhou Key Laboratory of Crop Gene Editing, Innovative Center of Molecular Genetics and Evolution, School of Life Sciences, Guangzhou Higher Education Mega Center, Guangzhou University, Guangzhou, China
| | - Min Liu
- Guangzhou Key Laboratory of Crop Gene Editing, Innovative Center of Molecular Genetics and Evolution, School of Life Sciences, Guangzhou Higher Education Mega Center, Guangzhou University, Guangzhou, China
- *Correspondence: Min Liu,
| | - Zhicheng Dong
- Guangzhou Key Laboratory of Crop Gene Editing, Innovative Center of Molecular Genetics and Evolution, School of Life Sciences, Guangzhou Higher Education Mega Center, Guangzhou University, Guangzhou, China
- Zhicheng Dong,
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40
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Rathore OS, Silva RD, Ascensão-Ferreira M, Matos R, Carvalho C, Marques B, Tiago MN, Prudêncio P, Andrade RP, Roignant JY, Barbosa-Morais NL, Martinho RG. NineTeen Complex-subunit Salsa is required for efficient splicing of a subset of introns and dorsal-ventral patterning. RNA (NEW YORK, N.Y.) 2020; 26:1935-1956. [PMID: 32963109 PMCID: PMC7668242 DOI: 10.1261/rna.077446.120] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Accepted: 09/07/2020] [Indexed: 06/11/2023]
Abstract
The NineTeen Complex (NTC), also known as pre-mRNA-processing factor 19 (Prp19) complex, regulates distinct spliceosome conformational changes necessary for splicing. During Drosophila midblastula transition, splicing is particularly sensitive to mutations in NTC-subunit Fandango, which suggests differential requirements of NTC during development. We show that NTC-subunit Salsa, the Drosophila ortholog of human RNA helicase Aquarius, is rate-limiting for splicing of a subset of small first introns during oogenesis, including the first intron of gurken Germline depletion of Salsa and splice site mutations within gurken first intron impair both adult female fertility and oocyte dorsal-ventral patterning, due to an abnormal expression of Gurken. Supporting causality, the fertility and dorsal-ventral patterning defects observed after Salsa depletion could be suppressed by the expression of a gurken construct without its first intron. Altogether, our results suggest that one of the key rate-limiting functions of Salsa during oogenesis is to ensure the correct expression and efficient splicing of the first intron of gurken mRNA. Retention of gurken first intron compromises the function of this gene most likely because it undermines the correct structure and function of the transcript 5'UTR.
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Affiliation(s)
- Om Singh Rathore
- Center for Biomedical Research (CBMR), Universidade do Algarve, Faro, 8005-139 Portugal
| | - Rui D Silva
- Center for Biomedical Research (CBMR), Universidade do Algarve, Faro, 8005-139 Portugal
| | - Mariana Ascensão-Ferreira
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Ricardo Matos
- Center for Biomedical Research (CBMR), Universidade do Algarve, Faro, 8005-139 Portugal
| | - Célia Carvalho
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Bruno Marques
- Center for Biomedical Research (CBMR), Universidade do Algarve, Faro, 8005-139 Portugal
| | - Margarida N Tiago
- Center for Biomedical Research (CBMR), Universidade do Algarve, Faro, 8005-139 Portugal
| | - Pedro Prudêncio
- Center for Biomedical Research (CBMR), Universidade do Algarve, Faro, 8005-139 Portugal
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Raquel P Andrade
- Center for Biomedical Research (CBMR), Universidade do Algarve, Faro, 8005-139 Portugal
- Department of Medicine and Biomedical Sciences and Algarve Biomedical Center, Universidade do Algarve, 8005-139 Faro, Portugal
| | - Jean-Yves Roignant
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, CH-1015 Lausanne, Switzerland
- Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg-University Mainz, 55128 Mainz, Germany
| | - Nuno L Barbosa-Morais
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Rui Gonçalo Martinho
- Center for Biomedical Research (CBMR), Universidade do Algarve, Faro, 8005-139 Portugal
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
- Department of Medical Sciences and Institute for Biomedicine (iBiMED), Universidade de Aveiro, 3810-193 Aveiro, Portugal
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41
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Reimer K, Neugebauer K. Preparation of Mammalian Nascent RNA for Long Read Sequencing. CURRENT PROTOCOLS IN MOLECULAR BIOLOGY 2020; 133:e128. [PMID: 33085989 PMCID: PMC7586757 DOI: 10.1002/cpmb.128] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Long read sequencing technologies now allow high-quality sequencing of RNAs (or their cDNAs) that are hundreds to thousands of nucleotides long. Long read sequences of nascent RNA provide single-nucleotide-resolution information about co-transcriptional RNA processing events-e.g., splicing, folding, and base modifications. Here, we describe how to isolate nascent RNA from mammalian cells through subcellular fractionation of chromatin-associated RNA, as well as how to deplete poly(A)+ RNA and rRNA, and, finally, how to generate a full-length cDNA library for use on long read sequencing platforms. This approach allows for an understanding of coordinated splicing status across multi-intron transcripts by revealing patterns of splicing or other RNA processing events that cannot be gained from traditional short read RNA sequencing. © 2020 Wiley Periodicals LLC. Basic Protocol 1: Subcellular fractionation Basic Protocol 2: Nascent RNA isolation and adapter ligation Basic Protocol 3: cDNA amplicon preparation.
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Affiliation(s)
- Kirsten Reimer
- Department of Molecular Biophysics and Biochemistry, Yale University, 333 Cedar Street, New Haven CT, 06520, 203-785-2358
| | - Karla Neugebauer
- Department of Molecular Biophysics and Biochemistry, Yale University, 333 Cedar Street, New Haven CT, 06520, 203-785-2358
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42
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Thompson MK, Kiourlappou M, Davis I. Ribo-Pop: simple, cost-effective, and widely applicable ribosomal RNA depletion. RNA (NEW YORK, N.Y.) 2020; 26:1731-1742. [PMID: 32759389 PMCID: PMC7566562 DOI: 10.1261/rna.076562.120] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 07/31/2020] [Indexed: 06/11/2023]
Abstract
The measurement of RNA abundance derived from massively parallel sequencing experiments is an essential technique. Methods that reduce ribosomal RNA levels are usually required prior to sequencing library construction because ribosomal RNA typically comprises the vast majority of a total RNA sample. For some experiments, ribosomal RNA depletion is favored over poly(A) selection because it offers a more inclusive representation of the transcriptome. However, methods to deplete ribosomal RNA are generally proprietary, complex, inefficient, applicable to only specific species, or compatible with only a narrow range of RNA input levels. Here, we describe Ribo-Pop (ribosomal RNA depletion for popular use), a simple workflow and antisense oligo design strategy that we demonstrate works over a wide input range and can be easily adapted to any organism with a sequenced genome. We provide a computational pipeline for probe selection, a streamlined 20-min protocol, and ready-to-use oligo sequences for several organisms. We anticipate that our simple and generalizable "open source" design strategy would enable virtually any laboratory to pursue full transcriptome sequencing in their organism of interest with minimal time and resource investment.
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Affiliation(s)
- Mary Kay Thompson
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, United Kingdom
| | - Maria Kiourlappou
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, United Kingdom
| | - Ilan Davis
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, United Kingdom
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43
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Grabski DF, Broseus L, Kumari B, Rekosh D, Hammarskjold ML, Ritchie W. Intron retention and its impact on gene expression and protein diversity: A review and a practical guide. WILEY INTERDISCIPLINARY REVIEWS-RNA 2020; 12:e1631. [PMID: 33073477 DOI: 10.1002/wrna.1631] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Revised: 09/16/2020] [Accepted: 09/23/2020] [Indexed: 12/12/2022]
Abstract
Intron retention (IR) occurs when a complete and unspliced intron remains in mature mRNA. An increasing body of literature has demonstrated a major role for IR in numerous biological functions, including several that impact human health and disease. Although experimental technologies used to study other forms of mRNA splicing can also be used to investigate IR, a specialized downstream computational analysis is optimal for IR discovery and analysis. Here we provide a review of IR and its biological implications, as well as a practical guide for how to detect and analyze it. Several methods, including long read third generation direct RNA sequencing, are described. We have developed an R package, FakIR, to facilitate the execution of the bioinformatic tasks recommended in this review and a tutorial on how to fit them to users aims. Additionally, we provide guidelines and experimental protocols to validate IR discovery and to evaluate the potential impact of IR on gene expression and protein output. This article is categorized under: RNA Evolution and Genomics > Computational Analyses of RNA RNA Processing > Splicing Regulation/Alternative Splicing RNA Methods > RNA Analyses in vitro and In Silico.
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Affiliation(s)
- David F Grabski
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia, USA.,Myles H. Thaler Center for AIDS and Human Retrovirus Research, University of Virginia, Charlottesville, Virginia, USA
| | - Lucile Broseus
- IGH, Centre National de la Recherche Scientifique, University of Montpellier, Montpellier, France
| | - Bandana Kumari
- IGH, Centre National de la Recherche Scientifique, University of Montpellier, Montpellier, France
| | - David Rekosh
- Myles H. Thaler Center for AIDS and Human Retrovirus Research, University of Virginia, Charlottesville, Virginia, USA.,Department of Microbiology, Immunology and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Marie-Louise Hammarskjold
- Myles H. Thaler Center for AIDS and Human Retrovirus Research, University of Virginia, Charlottesville, Virginia, USA.,Department of Microbiology, Immunology and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - William Ritchie
- IGH, Centre National de la Recherche Scientifique, University of Montpellier, Montpellier, France
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44
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Wei L, Lee S, Majumdar S, Zhang B, Sanfilippo P, Joseph B, Miura P, Soller M, Lai EC. Overlapping Activities of ELAV/Hu Family RNA Binding Proteins Specify the Extended Neuronal 3' UTR Landscape in Drosophila. Mol Cell 2020; 80:140-155.e6. [PMID: 33007254 DOI: 10.1016/j.molcel.2020.09.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 07/31/2020] [Accepted: 09/04/2020] [Indexed: 12/21/2022]
Abstract
The tissue-specific deployment of highly extended neural 3' UTR isoforms, generated by alternative polyadenylation (APA), is a broad and conserved feature of metazoan genomes. However, the factors and mechanisms that control neural APA isoforms are not well understood. Here, we show that three ELAV/Hu RNA binding proteins (Elav, Rbp9, and Fne) have similar capacities to induce a lengthened 3' UTR landscape in an ectopic setting. These factors promote accumulation of chromatin-associated, 3' UTR-extended, nascent transcripts, through inhibition of proximal polyadenylation site (PAS) usage. Notably, Elav represses an unannotated splice isoform of fne, switching the normally cytoplasmic Fne toward the nucleus in elav mutants. We use genomic profiling to reveal strong and broad loss of neural APA in elav/fne double mutant CNS, the first genetic background to largely abrogate this distinct APA signature. Overall, we demonstrate how regulatory interplay and functionally overlapping activities of neural ELAV/Hu RBPs drives the neural APA landscape.
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Affiliation(s)
- Lu Wei
- Department of Developmental Biology, Sloan Kettering Institute, New York, NY 10065, USA
| | - Seungjae Lee
- Department of Developmental Biology, Sloan Kettering Institute, New York, NY 10065, USA
| | - Sonali Majumdar
- Department of Developmental Biology, Sloan Kettering Institute, New York, NY 10065, USA
| | - Binglong Zhang
- Department of Developmental Biology, Sloan Kettering Institute, New York, NY 10065, USA
| | - Piero Sanfilippo
- Department of Developmental Biology, Sloan Kettering Institute, New York, NY 10065, USA; Louis V. Gerstner, Jr. Graduate School of Biomedical Sciences, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Brian Joseph
- Department of Developmental Biology, Sloan Kettering Institute, New York, NY 10065, USA; Louis V. Gerstner, Jr. Graduate School of Biomedical Sciences, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Pedro Miura
- Department of Developmental Biology, Sloan Kettering Institute, New York, NY 10065, USA; Department of Biology, University of Nevada, Reno, Reno, NV 89557, USA
| | - Matthias Soller
- School of Biosciences, College of Life and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, UK
| | - Eric C Lai
- Department of Developmental Biology, Sloan Kettering Institute, New York, NY 10065, USA.
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45
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Aslanzadeh V, Beggs JD. Revisiting the window of opportunity for cotranscriptional splicing in budding yeast. RNA (NEW YORK, N.Y.) 2020; 26:1081-1085. [PMID: 32439718 PMCID: PMC7430680 DOI: 10.1261/rna.075895.120] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We reported previously that, in budding yeast, transcription rate affects both the efficiency and fidelity of pre-mRNA splicing, especially of ribosomal protein transcripts. Here, we report that the majority of ribosomal protein transcripts with non-consensus 5' splice sites are spliced less efficiently when transcription is faster, and more efficiently with slower transcription. These results support the "window of opportunity" model, and we suggest a possible mechanism to explain these findings.
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Affiliation(s)
- Vahid Aslanzadeh
- Wellcome Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
| | - Jean D Beggs
- Wellcome Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
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46
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Jia J, Long Y, Zhang H, Li Z, Liu Z, Zhao Y, Lu D, Jin X, Deng X, Xia R, Cao X, Zhai J. Post-transcriptional splicing of nascent RNA contributes to widespread intron retention in plants. NATURE PLANTS 2020; 6:780-788. [PMID: 32541953 DOI: 10.1038/s41477-020-0688-1] [Citation(s) in RCA: 66] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 05/08/2020] [Indexed: 05/21/2023]
Abstract
In eukaryotes, genes are transcribed by RNA polymerase-II (Pol-II) and introns are removed by the spliceosome largely cotranscriptionally1-3; analysis using long-read sequencing revealed that splicing occurs immediately after Pol-II passes introns in yeast4,5. Here, we developed a Nanopore-based method to profile chromatin-bound RNA that enables the simultaneous detection of splicing status, Pol-II position and polyadenylation at the genome-wide scale in Arabidopsis. We found that more than half of the introns remain unspliced after Pol-II transcribes 1 kb past the 3' splice site, which is much slower than the rate of splicing reported in yeast4,5. Many of the full-length chromatin-bound RNA molecules are polyadenylated, yet still contain unspliced introns at specific positions. These introns are nearly absent in the cytoplasm and are resistant to nonsense-mediated decay, suggesting that they are post-transcriptionally spliced before the transcripts are released into the cytoplasm; we therefore termed these introns post-transcriptionally spliced introns (pts introns). Analysis of around 6,500 public RNA-sequencing libraries found that the splicing of pts introns requires the function of splicing-related proteins such as PRMT5 and SKIP, and is also influenced by various environmental signals. The majority of the intron retention events in Arabidopsis are at pts introns, suggesting that chromatin-tethered post-transcriptional splicing is a major contributor to the widespread intron retention that is observed in plants, and could be a mechanism to produce fully spliced functional mRNAs for rapid response.
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Affiliation(s)
- Jinbu Jia
- Institute of Plant and Food Science, Department of Biology, Southern University of Science and Technology, Shenzhen, China
- College of Horticulture, South China Agricultural University, Guangzhou, China
| | - Yanping Long
- Institute of Plant and Food Science, Department of Biology, Southern University of Science and Technology, Shenzhen, China
- Institute for Advanced Studies and College of Life Science, Wuhan University, Wuhan, China
| | - Hong Zhang
- Institute of Plant and Food Science, Department of Biology, Southern University of Science and Technology, Shenzhen, China
| | - Zhuowen Li
- Institute of Plant and Food Science, Department of Biology, Southern University of Science and Technology, Shenzhen, China
| | - Zhijian Liu
- Institute of Plant and Food Science, Department of Biology, Southern University of Science and Technology, Shenzhen, China
| | - Yan Zhao
- Institute of Plant and Food Science, Department of Biology, Southern University of Science and Technology, Shenzhen, China
| | - Dongdong Lu
- Institute of Plant and Food Science, Department of Biology, Southern University of Science and Technology, Shenzhen, China
| | - Xianhao Jin
- Institute of Plant and Food Science, Department of Biology, Southern University of Science and Technology, Shenzhen, China
| | - Xian Deng
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Rui Xia
- College of Horticulture, South China Agricultural University, Guangzhou, China
| | - Xiaofeng Cao
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
- Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Beijing, China
| | - Jixian Zhai
- Institute of Plant and Food Science, Department of Biology, Southern University of Science and Technology, Shenzhen, China.
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47
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Romanowski A, Schlaen RG, Perez-Santangelo S, Mancini E, Yanovsky MJ. Global transcriptome analysis reveals circadian control of splicing events in Arabidopsis thaliana. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 103:889-902. [PMID: 32314836 DOI: 10.1111/tpj.14776] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 03/26/2020] [Accepted: 04/01/2020] [Indexed: 05/21/2023]
Abstract
The circadian clock of Arabidopsis thaliana controls many physiological and molecular processes, allowing plants to anticipate daily changes in their environment. However, developing a detailed understanding of how oscillations in mRNA levels are connected to oscillations in co/post-transcriptional processes, such as splicing, has remained a challenge. Here we applied a combined approach using deep transcriptome sequencing and bioinformatics tools to identify novel circadian-regulated genes and splicing events. Using a stringent approach, we identified 300 intron retention, eight exon skipping, 79 alternative 3' splice site usage, 48 alternative 5' splice site usage, and 350 multiple (more than one event type) annotated events under circadian regulation. We also found seven and 721 novel alternative exonic and intronic events. Depletion of the circadian-regulated splicing factor AtSPF30 homologue resulted in the disruption of a subset of clock-controlled splicing events. Altogether, our global circadian RNA-seq coupled with an in silico, event-centred, splicing analysis tool offers a new approach for studying the interplay between the circadian clock and the splicing machinery at a global scale. The identification of many circadian-regulated splicing events broadens our current understanding of the level of control that the circadian clock has over this co/post-transcriptional regulatory layer.
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Affiliation(s)
- Andrés Romanowski
- Comparative Genomics of Plant Development, Fundación Instituto Leloir, Instituto de Investigaciones Bioquímicas Buenos Aires (IIBBA) - Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), C1405BWE, Buenos Aires, Argentina
| | - Rubén G Schlaen
- Comparative Genomics of Plant Development, Fundación Instituto Leloir, Instituto de Investigaciones Bioquímicas Buenos Aires (IIBBA) - Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), C1405BWE, Buenos Aires, Argentina
| | - Soledad Perez-Santangelo
- Comparative Genomics of Plant Development, Fundación Instituto Leloir, Instituto de Investigaciones Bioquímicas Buenos Aires (IIBBA) - Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), C1405BWE, Buenos Aires, Argentina
| | - Estefanía Mancini
- Comparative Genomics of Plant Development, Fundación Instituto Leloir, Instituto de Investigaciones Bioquímicas Buenos Aires (IIBBA) - Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), C1405BWE, Buenos Aires, Argentina
| | - Marcelo J Yanovsky
- Comparative Genomics of Plant Development, Fundación Instituto Leloir, Instituto de Investigaciones Bioquímicas Buenos Aires (IIBBA) - Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), C1405BWE, Buenos Aires, Argentina
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48
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Drexler HL, Choquet K, Churchman LS. Splicing Kinetics and Coordination Revealed by Direct Nascent RNA Sequencing through Nanopores. Mol Cell 2020; 77:985-998.e8. [PMID: 31839405 PMCID: PMC7060811 DOI: 10.1016/j.molcel.2019.11.017] [Citation(s) in RCA: 115] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 09/17/2019] [Accepted: 11/18/2019] [Indexed: 02/06/2023]
Abstract
Understanding how splicing events are coordinated across numerous introns in metazoan RNA transcripts requires quantitative analyses of transient RNA processing events in living cells. We developed nanopore analysis of co-transcriptional processing (nano-COP), in which nascent RNAs are directly sequenced through nanopores, exposing the dynamics and patterns of RNA splicing without biases introduced by amplification. Long nano-COP reads reveal that, in human and Drosophila cells, splicing occurs after RNA polymerase II transcribes several kilobases of pre-mRNA, suggesting that metazoan splicing transpires distally from the transcription machinery. Inhibition of the branch-site recognition complex SF3B rapidly diminished global co-transcriptional splicing. We found that splicing order does not strictly follow the order of transcription and is associated with cis-acting elements, alternative splicing, and RNA-binding factors. Further, neighboring introns in human cells tend to be spliced concurrently, implying that splicing of these introns occurs cooperatively. Thus, nano-COP unveils the organizational complexity of RNA processing.
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Affiliation(s)
- Heather L Drexler
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Karine Choquet
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - L Stirling Churchman
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA.
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49
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Broseus L, Ritchie W. Challenges in detecting and quantifying intron retention from next generation sequencing data. Comput Struct Biotechnol J 2020; 18:501-508. [PMID: 32206209 PMCID: PMC7078297 DOI: 10.1016/j.csbj.2020.02.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 11/29/2019] [Accepted: 02/15/2020] [Indexed: 12/17/2022] Open
Abstract
Intron retention (IR) occurs when an intron is transcribed into pre-mRNA and remains in the final mRNA. An increasing body of literature has demonstrated a major role for IR in numerous biological functions and in disease. Here we give an overview of the different computational approaches for detecting IR events from sequencing data. We show that these are based on different biological and computational assumptions that may lead to dramatically different results. We describe the various approaches for mitigating errors in detecting intron retention and for discovering IR signatures between different conditions.
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50
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Li S, Wang Y, Zhao Y, Zhao X, Chen X, Gong Z. Global Co-transcriptional Splicing in Arabidopsis and the Correlation with Splicing Regulation in Mature RNAs. MOLECULAR PLANT 2020; 13:266-277. [PMID: 31759129 PMCID: PMC8034514 DOI: 10.1016/j.molp.2019.11.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 11/01/2019] [Accepted: 11/07/2019] [Indexed: 05/20/2023]
Abstract
RNA splicing and spliceosome assembly in eukaryotes occur mainly during transcription. However, co-transcriptional splicing has not yet been explored in plants. Here, we built transcriptomes of nascent chromatin RNAs in Arabidopsis thaliana and showed that nearly all introns undergo co-transcriptional splicing, which occurs with higher efficiency for introns in protein-coding genes than for those in noncoding RNAs. Total intron number and intron position are two predominant features that correlate with co-transcriptional splicing efficiency, and introns with alternative 5' or 3' splice sites are less efficiently spliced. Furthermore, we found that mutations in genes encoding trans-acting proteins lead to more introns with increased splicing defects in nascent RNAs than in mature RNAs, and that introns with increased splicing defects in mature RNAs are inefficiently spliced at the co-transcriptional level. Collectively, our results not only uncovered widespread co-transcriptional splicing in Arabidopsis but also identified features that may affect or be affected by co-transcriptional splicing efficiency.
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Affiliation(s)
- Shaofang Li
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China; Joint Laboratory for International Cooperation in Crop Molecular Breeding, China Agricultural University, Beijing 100193, China.
| | - Yuan Wang
- Department of Botany and Plant Sciences, Institute of Integrative Genome Biology, University of California, Riverside, CA 92521, USA; Guangdong Provincial Key Laboratory for Plant Epigenetics, Longhua Institute of Innovative Biotechnology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518060, China; Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - Yonghui Zhao
- Department of Botany and Plant Sciences, Institute of Integrative Genome Biology, University of California, Riverside, CA 92521, USA; Plant Phenomics Research Center, Nanjing Agricultural University, Nanjing 210018, China
| | - Xinjie Zhao
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China; Joint Laboratory for International Cooperation in Crop Molecular Breeding, China Agricultural University, Beijing 100193, China
| | - Xuemei Chen
- Department of Botany and Plant Sciences, Institute of Integrative Genome Biology, University of California, Riverside, CA 92521, USA
| | - Zhizhong Gong
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China; Joint Laboratory for International Cooperation in Crop Molecular Breeding, China Agricultural University, Beijing 100193, China
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