1
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De Silva N, Lehman N, Fargason T, Paul T, Zhang Z, Zhang J. Unearthing a novel function of SRSF1 in binding and unfolding of RNA G-quadruplexes. Nucleic Acids Res 2024; 52:4676-4690. [PMID: 38567732 PMCID: PMC11077049 DOI: 10.1093/nar/gkae213] [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: 10/18/2023] [Revised: 02/28/2024] [Accepted: 03/13/2024] [Indexed: 04/14/2024] Open
Abstract
SRSF1 governs splicing of over 1500 mRNA transcripts. SRSF1 contains two RNA-recognition motifs (RRMs) and a C-terminal Arg/Ser-rich region (RS). It has been thought that SRSF1 RRMs exclusively recognize single-stranded exonic splicing enhancers, while RS lacks RNA-binding specificity. With our success in solving the insolubility problem of SRSF1, we can explore the unknown RNA-binding landscape of SRSF1. We find that SRSF1 RS prefers purine over pyrimidine. Moreover, SRSF1 binds to the G-quadruplex (GQ) from the ARPC2 mRNA, with both RRMs and RS being crucial. Our binding assays show that the traditional RNA-binding sites on the RRM tandem and the Arg in RS are responsible for GQ binding. Interestingly, our FRET and circular dichroism data reveal that SRSF1 unfolds the ARPC2 GQ, with RS leading unfolding and RRMs aiding. Our saturation transfer difference NMR results discover that Arg residues in SRSF1 RS interact with the guanine base but not other nucleobases, underscoring the uniqueness of the Arg/guanine interaction. Our luciferase assays confirm that SRSF1 can alleviate the inhibitory effect of GQ on gene expression in the cell. Given the prevalence of RNA GQ and SR proteins, our findings unveil unexplored SR protein functions with broad implications in RNA splicing and translation.
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Affiliation(s)
- Naiduwadura Ivon Upekala De Silva
- Department of Chemistry, College of Arts and Sciences, University of Alabama at Birmingham, CH266, 901 14th Street South, Birmingham, AL 35294-1240, USA
| | - Nathan Lehman
- Department of Chemistry, College of Arts and Sciences, University of Alabama at Birmingham, CH266, 901 14th Street South, Birmingham, AL 35294-1240, USA
| | - Talia Fargason
- Department of Chemistry, College of Arts and Sciences, University of Alabama at Birmingham, CH266, 901 14th Street South, Birmingham, AL 35294-1240, USA
| | - Trenton Paul
- Department of Chemistry, College of Arts and Sciences, University of Alabama at Birmingham, CH266, 901 14th Street South, Birmingham, AL 35294-1240, USA
| | - Zihan Zhang
- Department of Chemistry, College of Arts and Sciences, University of Alabama at Birmingham, CH266, 901 14th Street South, Birmingham, AL 35294-1240, USA
| | - Jun Zhang
- Department of Chemistry, College of Arts and Sciences, University of Alabama at Birmingham, CH266, 901 14th Street South, Birmingham, AL 35294-1240, USA
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2
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High Concentration or Combined Treatment of Antisense Oligonucleotides for Spinal Muscular Atrophy Perturbed SMN2 Splicing in Patient Fibroblasts. Genes (Basel) 2022; 13:genes13040685. [PMID: 35456491 PMCID: PMC9027857 DOI: 10.3390/genes13040685] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Revised: 04/07/2022] [Accepted: 04/08/2022] [Indexed: 02/04/2023] Open
Abstract
Spinal muscular atrophy (SMA) is caused by survival motor neuron 1 SMN1 deletion. The survival motor neuron 2 (SMN2) encodes the same protein as SMN1 does, but it has a splicing defect of exon 7. Some antisense oligonucleotides (ASOs) have been proven to correct this defect. One of these, nusinersen, is effective in SMA-affected infants, but not as much so in advanced-stage patients. Furthermore, the current regimen may exhibit a ceiling effect. To overcome these problems, high-dose ASOs or combined ASOs have been explored. Here, using SMA fibroblasts, we examined the effects of high-concentration ASOs and of combining two ASOs. Three ASOs were examined: one targeting intronic splicing suppressor site N1 (ISS-N1) in intron 7, and two others targeting the 3′ splice site and 5′ region of exon 8. In our experiments on all ASO types, a low or intermediate concentration (50 or 100 nM) showed better splicing efficiency than a high concentration (200 nM). In addition, a high concentration of each ASO created a cryptic exon in exon 6. When a mixture of two different ASOs (100 nM each) was added to the cells, the cryptic exon was included in the mRNA. In conclusion, ASOs at a high concentration or used in combination may show less splicing correction and cryptic exon creation.
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3
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Jobbins AM, Campagne S, Weinmeister R, Lucas CM, Gosliga AR, Clery A, Chen L, Eperon LP, Hodson MJ, Hudson AJ, Allain FHT, Eperon IC. Exon-independent recruitment of SRSF1 is mediated by U1 snRNP stem-loop 3. EMBO J 2022; 41:e107640. [PMID: 34779515 PMCID: PMC8724738 DOI: 10.15252/embj.2021107640] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 10/04/2021] [Accepted: 10/07/2021] [Indexed: 12/11/2022] Open
Abstract
SRSF1 protein and U1 snRNPs are closely connected splicing factors. They both stimulate exon inclusion, SRSF1 by binding to exonic splicing enhancer sequences (ESEs) and U1 snRNPs by binding to the downstream 5' splice site (SS), and both factors affect 5' SS selection. The binding of U1 snRNPs initiates spliceosome assembly, but SR proteins such as SRSF1 can in some cases substitute for it. The mechanistic basis of this relationship is poorly understood. We show here by single-molecule methods that a single molecule of SRSF1 can be recruited by a U1 snRNP. This reaction is independent of exon sequences and separate from the U1-independent process of binding to an ESE. Structural analysis and cross-linking data show that SRSF1 contacts U1 snRNA stem-loop 3, which is required for splicing. We suggest that the recruitment of SRSF1 to a U1 snRNP at a 5'SS is the basis for exon definition by U1 snRNP and might be one of the principal functions of U1 snRNPs in the core reactions of splicing in mammals.
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Affiliation(s)
- Andrew M Jobbins
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell BiologyUniversity of LeicesterLeicesterUK
- Present address:
MRC London Institute of Medical SciencesLondonUK
- Present address:
Institute of Clinical SciencesImperial College LondonLondonUK
| | - Sébastien Campagne
- Institute of BiochemistryETH ZürichSwitzerland
- Present address:
Inserm U1212CNRS UMR5320ARNA LaboratoryBordeaux CedexFrance
| | - Robert Weinmeister
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell BiologyUniversity of LeicesterLeicesterUK
- Leicester Institute of Structural & Chemical Biology and Department of ChemistryUniversity of LeicesterLeicesterUK
| | - Christian M Lucas
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell BiologyUniversity of LeicesterLeicesterUK
| | - Alison R Gosliga
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell BiologyUniversity of LeicesterLeicesterUK
- Present address:
Institut für Industrielle GenetikAbt.(eilung) SystembiologieUniversität StuttgartStuttgartGermany
| | | | - Li Chen
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell BiologyUniversity of LeicesterLeicesterUK
| | - Lucy P Eperon
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell BiologyUniversity of LeicesterLeicesterUK
| | - Mark J Hodson
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell BiologyUniversity of LeicesterLeicesterUK
| | - Andrew J Hudson
- Leicester Institute of Structural & Chemical Biology and Department of ChemistryUniversity of LeicesterLeicesterUK
| | | | - Ian C Eperon
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell BiologyUniversity of LeicesterLeicesterUK
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4
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Li L, Hobson L, Perry L, Clark B, Heavey S, Haider A, Sridhar A, Shaw G, Kelly J, Freeman A, Wilson I, Whitaker H, Nurmemmedov E, Oltean S, Porazinski S, Ladomery M. Targeting the ERG oncogene with splice-switching oligonucleotides as a novel therapeutic strategy in prostate cancer. Br J Cancer 2020; 123:1024-1032. [PMID: 32581342 PMCID: PMC7493922 DOI: 10.1038/s41416-020-0951-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 05/11/2020] [Accepted: 06/04/2020] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND The ERG oncogene, a member of the ETS family of transcription factor encoding genes, is a genetic driver of prostate cancer. It is activated through a fusion with the androgen-responsive TMPRSS2 promoter in 50% of cases. There is therefore significant interest in developing novel therapeutic agents that target ERG. We have taken an antisense approach and designed morpholino-based oligonucleotides that target ERG by inducing skipping of its constitutive exon 4. METHODS We designed antisense morpholino oligonucleotides (splice-switching oligonucleotides, SSOs) that target both the 5' and 3' splice sites of ERG's exon 4. We tested their efficacy in terms of inducing exon 4 skipping in two ERG-positive cell lines, VCaP prostate cancer cells and MG63 osteosarcoma cells. We measured their effect on cell proliferation, migration and apoptosis. We also tested their effect on xenograft tumour growth in mice and on ERG protein expression in a human prostate cancer radical prostatectomy sample ex vivo. RESULTS In VCaP cells, both SSOs were effective at inducing exon 4 skipping, which resulted in a reduction of overall ERG protein levels up to 96 h following a single transfection. SSO-induced ERG reduction decreased cell proliferation, cell migration and significantly increased apoptosis. We observed a concomitant reduction in protein levels for cyclin D1, c-Myc and the Wnt signalling pathway member β-catenin as well as a marker of activated Wnt signalling, p-LRP6. We tested the 3' splice site SSO in MG63 xenografts in mice and observed a reduction in tumour growth. We also demonstrated that the 3' splice site SSO caused a reduction in ERG expression in a patient-derived prostate tumour tissue cultured ex vivo. CONCLUSIONS We have successfully designed and tested morpholino-based SSOs that cause a marked reduction in ERG expression, resulting in decreased cell proliferation, a reduced migratory phenotype and increased apoptosis. Our initial tests on mouse xenografts and a human prostate cancer radical prostatectomy specimen indicate that SSOs can be effective for oncogene targeting in vivo. As such, this study encourages further in vivo therapeutic studies using SSOs targeting the ERG oncogene.
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Affiliation(s)
- Ling Li
- Institute of Biomedical & Clinical Sciences, University of Exeter Medical School, Exeter, UK
| | - Lisa Hobson
- Faculty of Health and Applied Sciences, University of the West of England, Bristol, UK
| | - Laura Perry
- Faculty of Health and Applied Sciences, University of the West of England, Bristol, UK
| | - Bethany Clark
- Faculty of Health and Applied Sciences, University of the West of England, Bristol, UK
| | - Susan Heavey
- Molecular Diagnostics and Therapeutics Group, University College London, London, UK
| | - Aiman Haider
- Department of Pathology, UCLH NHS Foundation Trust, London, UK
| | - Ashwin Sridhar
- Department of Urology, UCLH NHS Foundation Trust, London, UK
| | - Greg Shaw
- Department of Urology, UCLH NHS Foundation Trust, London, UK
| | - John Kelly
- Department of Urology, UCLH NHS Foundation Trust, London, UK
| | - Alex Freeman
- Department of Pathology, UCLH NHS Foundation Trust, London, UK
| | - Ian Wilson
- Faculty of Health and Applied Sciences, University of the West of England, Bristol, UK
| | - Hayley Whitaker
- Molecular Diagnostics and Therapeutics Group, University College London, London, UK
| | - Elmar Nurmemmedov
- John Wayne Cancer Institute, Providence Saint John's Health Center, Santa Monica, USA
| | - Sebastian Oltean
- Institute of Biomedical & Clinical Sciences, University of Exeter Medical School, Exeter, UK
| | - Sean Porazinski
- Faculty of Health and Applied Sciences, University of the West of England, Bristol, UK.
- Faculty of Medicine, St Vincent's Clinical School, University of NSW, Darlinghurst, Sydney, NSW, 2010, Australia.
| | - Michael Ladomery
- Faculty of Health and Applied Sciences, University of the West of England, Bristol, UK.
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5
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Neckles C, Boer RE, Aboreden N, Cross AM, Walker RL, Kim BH, Kim S, Schneekloth JS, Caplen NJ. HNRNPH1-dependent splicing of a fusion oncogene reveals a targetable RNA G-quadruplex interaction. RNA (NEW YORK, N.Y.) 2019; 25:1731-1750. [PMID: 31511320 PMCID: PMC6859848 DOI: 10.1261/rna.072454.119] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 09/08/2019] [Indexed: 05/05/2023]
Abstract
The primary oncogenic event in ∼85% of Ewing sarcomas is a chromosomal translocation that generates a fusion oncogene encoding an aberrant transcription factor. The exact genomic breakpoints within the translocated genes, EWSR1 and FLI1, vary; however, in EWSR1, breakpoints typically occur within introns 7 or 8. We previously found that in Ewing sarcoma cells harboring EWSR1 intron 8 breakpoints, the RNA-binding protein HNRNPH1 facilitates a splicing event that excludes EWSR1 exon 8 from the EWS-FLI1 pre-mRNA to generate an in-frame mRNA. Here, we show that the processing of distinct EWS-FLI1 pre-mRNAs by HNRNPH1, but not other homologous family members, resembles alternative splicing of transcript variants of EWSR1 We demonstrate that HNRNPH1 recruitment is driven by guanine-rich sequences within EWSR1 exon 8 that have the potential to fold into RNA G-quadruplex structures. Critically, we demonstrate that an RNA mimetic of one of these G-quadruplexes modulates HNRNPH1 binding and induces a decrease in the growth of an EWSR1 exon 8 fusion-positive Ewing sarcoma cell line. Finally, we show that EWSR1 exon 8 fusion-positive cell lines are more sensitive to treatment with the pan-quadruplex binding molecule, pyridostatin (PDS), than EWSR1 exon 8 fusion-negative lines. Also, the treatment of EWSR1 exon 8 fusion-positive cells with PDS decreases EWS-FLI1 transcriptional activity, reversing the transcriptional deregulation driven by EWS-FLI1. Our findings illustrate that modulation of the alternative splicing of EWS-FLI1 pre-mRNA is a novel strategy for future therapeutics against the EWSR1 exon 8 containing fusion oncogenes present in a third of Ewing sarcoma.
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Affiliation(s)
- Carla Neckles
- Functional Genetics Section, Genetics Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892, USA
| | - Robert E Boer
- Chemical Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, Maryland 21702, USA
| | - Nicholas Aboreden
- Functional Genetics Section, Genetics Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892, USA
| | - Allison M Cross
- Functional Genetics Section, Genetics Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892, USA
| | - Robert L Walker
- Molecular Genetics Section, Genetics Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892, USA
| | - Bong-Hyun Kim
- CCR Collaborative Bioinformatics Resource, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, Maryland 21702, USA
| | - Suntae Kim
- Functional Genetics Section, Genetics Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892, USA
| | - John S Schneekloth
- Chemical Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, Maryland 21702, USA
| | - Natasha J Caplen
- Functional Genetics Section, Genetics Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892, USA
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6
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Jobbins AM, Reichenbach LF, Lucas CM, Hudson AJ, Burley GA, Eperon IC. The mechanisms of a mammalian splicing enhancer. Nucleic Acids Res 2019; 46:2145-2158. [PMID: 29394380 PMCID: PMC5861446 DOI: 10.1093/nar/gky056] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 01/19/2018] [Indexed: 12/21/2022] Open
Abstract
Exonic splicing enhancer (ESE) sequences are bound by serine & arginine-rich (SR) proteins, which in turn enhance the recruitment of splicing factors. It was inferred from measurements of splicing around twenty years ago that Drosophila doublesex ESEs are bound stably by SR proteins, and that the bound proteins interact directly but with low probability with their targets. However, it has not been possible with conventional methods to demonstrate whether mammalian ESEs behave likewise. Using single molecule multi-colour colocalization methods to study SRSF1-dependent ESEs, we have found that that the proportion of RNA molecules bound by SRSF1 increases with the number of ESE repeats, but only a single molecule of SRSF1 is bound. We conclude that initial interactions between SRSF1 and an ESE are weak and transient, and that these limit the activity of a mammalian ESE. We tested whether the activation step involves the propagation of proteins along the RNA or direct interactions with 3' splice site components by inserting hexaethylene glycol or abasic RNA between the ESE and the target 3' splice site. These insertions did not block activation, and we conclude that the activation step involves direct interactions. These results support a model in which regulatory proteins bind transiently and in dynamic competition, with the result that each ESE in an exon contributes independently to the probability that an activator protein is bound and in close proximity to a splice site.
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Affiliation(s)
- Andrew M Jobbins
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell Biology, University of Leicester, UK
| | | | - Christian M Lucas
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell Biology, University of Leicester, UK
| | - Andrew J Hudson
- Leicester Institute of Structural & Chemical Biology and Department of Chemistry, University of Leicester, UK
| | - Glenn A Burley
- Department of Pure and Applied Chemistry, University of Strathclyde, UK
| | - Ian C Eperon
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell Biology, University of Leicester, UK
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7
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Weldon C, Dacanay JG, Gokhale V, Boddupally PVL, Behm-Ansmant I, Burley GA, Branlant C, Hurley LH, Dominguez C, Eperon IC. Specific G-quadruplex ligands modulate the alternative splicing of Bcl-X. Nucleic Acids Res 2019; 46:886-896. [PMID: 29156002 PMCID: PMC5778605 DOI: 10.1093/nar/gkx1122] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Accepted: 10/26/2017] [Indexed: 12/23/2022] Open
Abstract
Sequences with the potential to form RNA G-quadruplexes (G4s) are common in mammalian introns, especially in the proximity of the 5′ splice site (5′SS). However, the difficulty of demonstrating that G4s form in pre-mRNA in functional conditions has meant that little is known about their effects or mechanisms of action. We have shown previously that two G4s form in Bcl-X pre-mRNA, one close to each of the two alternative 5′SS. If these G4s affect splicing but are in competition with other RNA structures or RNA binding proteins, then ligands that stabilize them would increase the proportion of Bcl-X pre-mRNA molecules in which either or both G4s had formed, shifting Bcl-X splicing. We show here that a restricted set of G4 ligands do affect splicing, that their activity and specificity are strongly dependent on their structures and that they act independently at the two splice sites. One of the ligands, the ellipticine GQC-05, antagonizes the major 5′SS that expresses the anti-apoptotic isoform of Bcl-X and activates the alternative 5′SS that expresses a pro-apoptotic isoform. We propose mechanisms that would account for these see-saw effects and suggest that these effects contribute to the ability of GQC-05 to induce apoptosis.
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Affiliation(s)
- Carika Weldon
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell Biology, University of Leicester, Leicester LE1 7RH, UK
| | - Justine G Dacanay
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell Biology, University of Leicester, Leicester LE1 7RH, UK
| | - Vijay Gokhale
- College of Pharmacy and College of Pharmacy and BIO5 Institute, University of Arizona, Tucson, AZ 85721, USA
| | - Peda Venkat L Boddupally
- Fluoroorganic Division, CSIR-Indian Institute of Chemical Technology, Hyderabad, Telangana 500 007, India
| | - Isabelle Behm-Ansmant
- IMoPA (Ingénierie Moléculaire et Physiopathologie Articulaire), UMR 7365 CNRS-UL, Biopôle de l'Université de Lorraine, 9 Avenue de la Forêt de Haye, 54505 Vandoeuvre-lès-Nancy, France
| | - Glenn A Burley
- Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow G1 1XL, UK
| | - Christiane Branlant
- IMoPA (Ingénierie Moléculaire et Physiopathologie Articulaire), UMR 7365 CNRS-UL, Biopôle de l'Université de Lorraine, 9 Avenue de la Forêt de Haye, 54505 Vandoeuvre-lès-Nancy, France
| | - Laurence H Hurley
- College of Pharmacy and College of Pharmacy and BIO5 Institute, University of Arizona, Tucson, AZ 85721, USA.,Arizona Cancer Center, University of Arizona, Tucson, AZ 85724, USA
| | - Cyril Dominguez
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell Biology, University of Leicester, Leicester LE1 7RH, UK
| | - Ian C Eperon
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell Biology, University of Leicester, Leicester LE1 7RH, UK
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8
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Taladriz-Sender A, Campbell E, Burley GA. Splice-switching small molecules: A new therapeutic approach to modulate gene expression. Methods 2019; 167:134-142. [PMID: 31203161 DOI: 10.1016/j.ymeth.2019.06.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Revised: 06/10/2019] [Accepted: 06/11/2019] [Indexed: 12/12/2022] Open
Abstract
Manipulating alternative RNA splicing events with small molecules is emerging as a viable mechanism for the development of therapeutics. A salient challenge in the field is understanding the molecular determinants defining the selectivity of splice-switching events and their mechanisms of action. In this review, the current state-of-the-art in splice-switching small molecules is described. Three examples of splice-switching small molecules are presented, and the differences in their modes of action compared.
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Affiliation(s)
- Andrea Taladriz-Sender
- Department of Pure and Applied Chemistry, University of Strathclyde. Thomas Graham Building, 295 Cathedral Street, Glasgow G1 1XL, United Kingdom
| | - Emma Campbell
- Department of Pure and Applied Chemistry, University of Strathclyde. Thomas Graham Building, 295 Cathedral Street, Glasgow G1 1XL, United Kingdom
| | - Glenn A Burley
- Department of Pure and Applied Chemistry, University of Strathclyde. Thomas Graham Building, 295 Cathedral Street, Glasgow G1 1XL, United Kingdom.
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9
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Chen L, Weinmeister R, Kralovicova J, Eperon LP, Vorechovsky I, Hudson AJ, Eperon IC. Stoichiometries of U2AF35, U2AF65 and U2 snRNP reveal new early spliceosome assembly pathways. Nucleic Acids Res 2017; 45:2051-2067. [PMID: 27683217 PMCID: PMC5389562 DOI: 10.1093/nar/gkw860] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 09/16/2016] [Indexed: 12/24/2022] Open
Abstract
The selection of 3΄ splice sites (3΄ss) is an essential early step in mammalian RNA splicing reactions, but the processes involved are unknown. We have used single molecule methods to test whether the major components implicated in selection, the proteins U2AF35 and U2AF65 and the U2 snRNP, are able to recognize alternative candidate sites or are restricted to one pre-specified site. In the presence of adenosine triphosphate (ATP), all three components bind in a 1:1 stoichiometry with a 3΄ss. Pre-mRNA molecules with two alternative 3΄ss can be bound concurrently by two molecules of U2AF or two U2 snRNPs, so none of the components are restricted. However, concurrent occupancy inhibits splicing. Stoichiometric binding requires conditions consistent with coalescence of the 5΄ and 3΄ sites in a complex (I, initial), but if this cannot form the components show unrestricted and stochastic association. In the absence of ATP, when complex E forms, U2 snRNP association is unrestricted. However, if protein dephosphorylation is prevented, an I-like complex forms with stoichiometric association of U2 snRNPs and the U2 snRNA is base-paired to the pre-mRNA. Complex I differs from complex A in that the formation of complex A is associated with the loss of U2AF65 and 35.
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Affiliation(s)
- Li Chen
- University of Leicester, Leicester Institute for Structural and Chemical Biology and Department of Molecular and Cell Biology, Leicester LE1 9HN, UK
| | - Robert Weinmeister
- University of Leicester, Leicester Institute for Structural and Chemical Biology and Department of Molecular and Cell Biology, Leicester LE1 9HN, UK
| | - Jana Kralovicova
- University of Southampton, Faculty of Medicine, Southampton SO16 6YD, UK
| | - Lucy P Eperon
- University of Leicester, Leicester Institute for Structural and Chemical Biology and Department of Molecular and Cell Biology, Leicester LE1 9HN, UK
| | - Igor Vorechovsky
- University of Southampton, Faculty of Medicine, Southampton SO16 6YD, UK
| | - Andrew J Hudson
- University of Leicester, Leicester Institute for Structural and Chemical Biology and Department of Chemistry, Leicester LE1 7RH, UK
| | - Ian C Eperon
- University of Leicester, Leicester Institute for Structural and Chemical Biology and Department of Molecular and Cell Biology, Leicester LE1 9HN, UK
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10
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Weldon C, Behm-Ansmant I, Hurley LH, Burley GA, Branlant C, Eperon IC, Dominguez C. Identification of G-quadruplexes in long functional RNAs using 7-deazaguanine RNA. Nat Chem Biol 2017; 13:18-20. [PMID: 27820800 PMCID: PMC5164935 DOI: 10.1038/nchembio.2228] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Accepted: 08/31/2016] [Indexed: 01/24/2023]
Abstract
RNA G-quadruplex (G4) structures are thought to affect biological processes, including translation and pre-mRNA splicing, but it is not possible at present to demonstrate that they form naturally at specific sequences in long functional RNA molecules. We developed a new strategy, footprinting of long 7-deazaguanine-substituted RNAs (FOLDeR), that allows the formation of G4s to be confirmed in long RNAs and under functional conditions.
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Affiliation(s)
- Carika Weldon
- Leicester Institute of Structural and Chemical Biology and Department of Molecular and Cell Biology, University of Leicester, Leicester, UK
| | - Isabelle Behm-Ansmant
- IMoPA (Ingénierie Moléculaire et Physiopathologie Articulaire), UMR 7365 CNRS-UL, Biopôle de l’Université de Lorraine, 9 Avenue de la Forêt de Haye, 54505 Vandoeuvre-lès-Nancy, France
| | - Laurence H. Hurley
- College of Pharmacy and College of Pharmacy and BIO5 Institute, University of Arizona, Tucson, Arizona 85721, United States
- Arizona Cancer Center, University of Arizona, Tucson, Arizona 85724, United States
| | - Glenn A. Burley
- Department of Pure and Applied Chemistry, University of Strathclyde, UK
| | - Christiane Branlant
- IMoPA (Ingénierie Moléculaire et Physiopathologie Articulaire), UMR 7365 CNRS-UL, Biopôle de l’Université de Lorraine, 9 Avenue de la Forêt de Haye, 54505 Vandoeuvre-lès-Nancy, France
| | - Ian C. Eperon
- Leicester Institute of Structural and Chemical Biology and Department of Molecular and Cell Biology, University of Leicester, Leicester, UK
| | - Cyril Dominguez
- Leicester Institute of Structural and Chemical Biology and Department of Molecular and Cell Biology, University of Leicester, Leicester, UK
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11
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Abstract
More than 95% of genes in the human genome are alternatively spliced to form multiple transcripts, often encoding proteins with differing or opposing function. The control of alternative splicing is now being elucidated, and with this comes the opportunity to develop modulators of alternative splicing that can control cellular function. A number of approaches have been taken to develop compounds that can experimentally, and sometimes clinically, affect splicing control, resulting in potential novel therapeutics. Here we develop the concepts that targeting alternative splicing can result in relatively specific pathway inhibitors/activators that result in dampening down of physiologic or pathologic processes, from changes in muscle physiology to altering angiogenesis or pain. The targets and pharmacology of some of the current inhibitors/activators of alternative splicing are demonstrated and future directions discussed.
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Affiliation(s)
- David O Bates
- Cancer Biology, Division of Cancer and Stem Cells, School of Medicine, University of Nottingham, Queen's Medical Centre, Nottingham, United Kingdom (D.O.B.); School of Chemistry, UNSW Australia, Sydney, Australia (J.C.M.); School of Physiology, Pharmacology and Neurosciences, School of Clinical Sciences/Bristol Renal, University of Bristol, Bristol, United Kingdom (S.O.); and School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, United Kingdom (L.F.D.)
| | - Jonathan C Morris
- Cancer Biology, Division of Cancer and Stem Cells, School of Medicine, University of Nottingham, Queen's Medical Centre, Nottingham, United Kingdom (D.O.B.); School of Chemistry, UNSW Australia, Sydney, Australia (J.C.M.); School of Physiology, Pharmacology and Neurosciences, School of Clinical Sciences/Bristol Renal, University of Bristol, Bristol, United Kingdom (S.O.); and School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, United Kingdom (L.F.D.)
| | - Sebastian Oltean
- Cancer Biology, Division of Cancer and Stem Cells, School of Medicine, University of Nottingham, Queen's Medical Centre, Nottingham, United Kingdom (D.O.B.); School of Chemistry, UNSW Australia, Sydney, Australia (J.C.M.); School of Physiology, Pharmacology and Neurosciences, School of Clinical Sciences/Bristol Renal, University of Bristol, Bristol, United Kingdom (S.O.); and School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, United Kingdom (L.F.D.)
| | - Lucy F Donaldson
- Cancer Biology, Division of Cancer and Stem Cells, School of Medicine, University of Nottingham, Queen's Medical Centre, Nottingham, United Kingdom (D.O.B.); School of Chemistry, UNSW Australia, Sydney, Australia (J.C.M.); School of Physiology, Pharmacology and Neurosciences, School of Clinical Sciences/Bristol Renal, University of Bristol, Bristol, United Kingdom (S.O.); and School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, United Kingdom (L.F.D.)
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Weldon C, Eperon IC, Dominguez C. Do we know whether potential G-quadruplexes actually form in long functional RNA molecules? Biochem Soc Trans 2016; 44:1761-1768. [PMID: 27913687 PMCID: PMC5135001 DOI: 10.1042/bst20160109] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 06/30/2016] [Accepted: 07/04/2016] [Indexed: 01/25/2023]
Abstract
The roles of deoxyribonucleic acid (DNA) G-quadruplex structures in gene expression and telomere maintenance have been well characterized. Recent results suggest that such structures could also play pivotal roles in ribonucleic acid (RNA) biology, such as splicing or translation regulation. However, it has been difficult to show that RNA G-quadruplexes (G4s) exist in specific long RNA sequences, such as precursor messenger RNA, in a functional or cellular context. Most current methods for identifying G4s involve the use of short, purified RNA sequences in vitro, in the absence of competition with secondary structures or protein binding. Therefore, novel methods need to be developed to allow the characterization of G4s in long functional RNAs and in a cellular context. This need has in part been met by our recent development of a method based on a comparison of RNA and 7-deaza-RNA that provides a test for identifying RNA G4s in such conditions.
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Affiliation(s)
- Carika Weldon
- Leicester Institute of Structural and Chemical Biology and Department of Molecular and Cellular Biology, University of Leicester, Lancaster Road, Leicester LE1 9HN, U.K
| | - Ian C Eperon
- Leicester Institute of Structural and Chemical Biology and Department of Molecular and Cellular Biology, University of Leicester, Lancaster Road, Leicester LE1 9HN, U.K
| | - Cyril Dominguez
- Leicester Institute of Structural and Chemical Biology and Department of Molecular and Cellular Biology, University of Leicester, Lancaster Road, Leicester LE1 9HN, U.K
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Mechanistic principles of antisense targets for the treatment of spinal muscular atrophy. Future Med Chem 2015; 7:1793-808. [PMID: 26381381 DOI: 10.4155/fmc.15.101] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Spinal muscular atrophy (SMA) is a major neurodegenerative disorder of children and infants. SMA is primarily caused by low levels of SMN protein owing to deletions or mutations of the SMN1 gene. SMN2, a nearly identical copy of SMN1, fails to compensate for the loss of the production of the functional SMN protein due to predominant skipping of exon 7. Several compounds, including antisense oligonucleotides (ASOs) that elevate SMN protein from SMN2 hold the promise for treatment. An ASO-based drug currently under Phase III clinical trial employs intronic splicing silencer N1 (ISS-N1) as its target. Cumulative studies on ISS-N1 reveal a wealth of information with significance to the overall therapeutic development for SMA. Here, the authors summarize the mechanistic principles behind various antisense targets currently available for SMA therapy.
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