1
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Nagasawa CK, Garcia-Blanco MA. Early Splicing Complexes and Human Disease. Int J Mol Sci 2023; 24:11412. [PMID: 37511171 PMCID: PMC10379813 DOI: 10.3390/ijms241411412] [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: 06/18/2023] [Revised: 07/07/2023] [Accepted: 07/10/2023] [Indexed: 07/30/2023] Open
Abstract
Over the last decade, our understanding of spliceosome structure and function has significantly improved, refining the study of the impact of dysregulated splicing on human disease. As a result, targeted splicing therapeutics have been developed, treating various diseases including spinal muscular atrophy and Duchenne muscular dystrophy. These advancements are very promising and emphasize the critical role of proper splicing in maintaining human health. Herein, we provide an overview of the current information on the composition and assembly of early splicing complexes-commitment complex and pre-spliceosome-and their association with human disease.
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Affiliation(s)
- Chloe K. Nagasawa
- Human Pathophysiology and Translational Medicine Program, Institute for Translational Sciences, University of Texas Medical Branch, Galveston, TX 77555-5302, USA;
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555-5302, USA
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, VA 22903-2628, USA
| | - Mariano A. Garcia-Blanco
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555-5302, USA
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, VA 22903-2628, USA
- Institute of Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX 77555-5302, USA
- Department of Internal Medicine, University of Texas Medical Branch, Galveston, TX 77555-5302, USA
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2
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Vester K, Preußner M, Holton N, Feng S, Schultz C, Heyd F, Wahl MC. Recruitment of a splicing factor to the nuclear lamina for its inactivation. Commun Biol 2022; 5:736. [PMID: 35869234 PMCID: PMC9307855 DOI: 10.1038/s42003-022-03689-y] [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: 01/09/2022] [Accepted: 07/08/2022] [Indexed: 11/10/2022] Open
Abstract
Precursor messenger RNA splicing is a highly regulated process, mediated by a complex RNA-protein machinery, the spliceosome, that encompasses several hundred proteins and five small nuclear RNAs in humans. Emerging evidence suggests that the spatial organization of splicing factors and their spatio-temporal dynamics participate in the regulation of splicing. So far, methods to manipulate the spatial distribution of splicing factors in a temporally defined manner in living cells are missing. Here, we describe such an approach that takes advantage of a reversible chemical dimerizer, and outline the requirements for efficient, reversible re-localization of splicing factors to selected sub-nuclear compartments. In a proof-of-principle study, the partial re-localization of the PRPF38A protein to the nuclear lamina in HEK293T cells induced a moderate increase in intron retention. Our approach allows fast and reversible re-localization of splicing factors, has few side effects and can be applied to many splicing factors by fusion of a protein tag through genome engineering. Apart from the systematic analysis of the spatio-temporal aspects of splicing regulation, the approach has a large potential for the fast induction and reversal of splicing switches and can reveal mechanisms of splicing regulation in native nuclear environments. Through the use of a reversible chemical dimerizer, the splicing factor PRPF38A is re-localized to the nuclear lamina, paving the way for a systematic analysis of spatio-temporal splicing regulation.
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3
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Sette C, Paronetto MP. Somatic Mutations in Core Spliceosome Components Promote Tumorigenesis and Generate an Exploitable Vulnerability in Human Cancer. Cancers (Basel) 2022; 14:cancers14071827. [PMID: 35406598 PMCID: PMC8997811 DOI: 10.3390/cancers14071827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 03/30/2022] [Accepted: 03/30/2022] [Indexed: 12/02/2022] Open
Abstract
Simple Summary High throughput exome sequencing approaches have disclosed recurrent cancer-associated mutations in spliceosomal components, which drive aberrant pre-mRNA processing events and support the tumor phenotype. At the same time, mutations in spliceosome genes and aberrant splicing regulation establish a selective vulnerability of cancer cells to splicing-targeting approaches, which could be exploited therapeutically. It is conceivable that a better understanding of the mechanisms and roles of abnormal splicing in tumor metabolism will facilitate the development of a novel generation of tumor-targeting drugs. In this review, we describe recent advances in the elucidation of the biological impact and biochemical effects of somatic mutations in core spliceosome components on splicing choices and their associated targetable vulnerabilities. Abstract Alternative pre-mRNA processing enables the production of distinct mRNA and protein isoforms from a single gene, thus greatly expanding the coding potential of eukaryotic genomes and fine-tuning gene expression programs. Splicing is carried out by the spliceosome, a complex molecular machinery which assembles step-wise on mRNA precursors in the nucleus of eukaryotic cells. In the last decade, exome sequencing technologies have allowed the identification of point mutations in genes encoding splicing factors as a recurrent hallmark of human cancers, with higher incidence in hematological malignancies. These mutations lead to production of splicing factors that reduce the fidelity of the splicing process and yield splicing variants that are often advantageous for cancer cells. However, at the same time, these mutations increase the sensitivity of transformed cells to splicing inhibitors, thus offering a therapeutic opportunity for novel targeted strategies. Herein, we review the recent literature documenting cancer-associated mutations in components of the early spliceosome complex and discuss novel therapeutic strategies based on small-molecule spliceosome inhibitors that exhibit strong anti-tumor effects, particularly against cancer cells harboring mutations in spliceosomal components.
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Affiliation(s)
- Claudio Sette
- Department of Neuroscience, Section of Human Anatomy, Catholic University of the Sacred Heart, 00168 Rome, Italy;
- GSTEP-Organoids Core Facility, Fondazione Policlinico Agostino Gemelli IRCCS, 00168 Rome, Italy
| | - Maria Paola Paronetto
- Department of Movement, Human and Health Sciences, University of Rome “Foro Italico”, Piazza Lauro De Bosis, 6, 00135 Rome, Italy
- Laboratory of Molecular and Cellular Neurobiology, Fondazione Santa Lucia, IRCCS, Via del Fosso di Fiorano 64, 00143 Rome, Italy
- Correspondence:
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4
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Escobar H, Krause A, Keiper S, Kieshauer J, Müthel S, de Paredes MG, Metzler E, Kühn R, Heyd F, Spuler S. Base editing repairs an SGCA mutation in human primary muscle stem cells. JCI Insight 2021; 6:145994. [PMID: 33848270 PMCID: PMC8262330 DOI: 10.1172/jci.insight.145994] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 04/07/2021] [Indexed: 11/28/2022] Open
Abstract
Skeletal muscle can regenerate from muscle stem cells and their myogenic precursor cell progeny, myoblasts. However, precise gene editing in human muscle stem cells for autologous cell replacement therapies of untreatable genetic muscle diseases has not yet been reported. Loss-of-function mutations in SGCA, encoding α-sarcoglycan, cause limb-girdle muscular dystrophy 2D/R3, an early-onset, severe, and rapidly progressive form of muscular dystrophy affecting both male and female patients. Patients suffer from muscle degeneration and atrophy affecting the limbs, respiratory muscles, and heart. We isolated human muscle stem cells from 2 donors, with the common SGCA c.157G>A mutation affecting the last coding nucleotide of exon 2. We found that c.157G>A is an exonic splicing mutation that induces skipping of 2 coregulated exons. Using adenine base editing, we corrected the mutation in the cells from both donors with > 90% efficiency, thereby rescuing the splicing defect and α-sarcoglycan expression. Base-edited patient cells regenerated muscle and contributed to the Pax7+ satellite cell compartment in vivo in mouse xenografts. Here, we provide the first evidence to our knowledge that autologous gene–repaired human muscle stem cells can be harnessed for cell replacement therapies of muscular dystrophies.
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Affiliation(s)
- Helena Escobar
- Muscle Research Unit, Experimental and Clinical Research Center, a cooperation between the Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association and the Charité, Universitätsmedizin Berlin, Germany.,Charité Universitätsmedizin Berlin, Germany.,Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Anne Krause
- Muscle Research Unit, Experimental and Clinical Research Center, a cooperation between the Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association and the Charité, Universitätsmedizin Berlin, Germany.,Charité Universitätsmedizin Berlin, Germany.,Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Sandra Keiper
- Freie Universität Berlin, Institute of Chemistry and Biochemistry, Laboratory of RNA Biochemistry, Berlin, Germany
| | - Janine Kieshauer
- Muscle Research Unit, Experimental and Clinical Research Center, a cooperation between the Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association and the Charité, Universitätsmedizin Berlin, Germany.,Charité Universitätsmedizin Berlin, Germany.,Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Stefanie Müthel
- Muscle Research Unit, Experimental and Clinical Research Center, a cooperation between the Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association and the Charité, Universitätsmedizin Berlin, Germany.,Charité Universitätsmedizin Berlin, Germany.,Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Manuel García de Paredes
- Muscle Research Unit, Experimental and Clinical Research Center, a cooperation between the Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association and the Charité, Universitätsmedizin Berlin, Germany
| | - Eric Metzler
- Muscle Research Unit, Experimental and Clinical Research Center, a cooperation between the Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association and the Charité, Universitätsmedizin Berlin, Germany.,Charité Universitätsmedizin Berlin, Germany.,Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Ralf Kühn
- Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Florian Heyd
- Freie Universität Berlin, Institute of Chemistry and Biochemistry, Laboratory of RNA Biochemistry, Berlin, Germany
| | - Simone Spuler
- Muscle Research Unit, Experimental and Clinical Research Center, a cooperation between the Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association and the Charité, Universitätsmedizin Berlin, Germany
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5
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Herdt O, Reich S, Medenbach J, Timmermann B, Olofsson D, Preußner M, Heyd F. The zinc finger domains in U2AF26 and U2AF35 have diverse functionalities including a role in controlling translation. RNA Biol 2020; 17:843-856. [PMID: 32116123 DOI: 10.1080/15476286.2020.1732701] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Recent work has associated point mutations in both zinc fingers (ZnF) of the spliceosome component U2AF35 with malignant transformation. However, surprisingly little is known about the functionality of the U2AF35 ZnF domains in general. Here we have analysed key functionalities of the ZnF domains of mammalian U2AF35 and its paralog U2AF26. Both ZnFs are required for splicing regulation, whereas only ZnF2 controls protein stability and contributes to the interaction with U2AF65. These features are confirmed in a naturally occurring splice variant of U2AF26 lacking ZnF2, that is strongly induced upon activation of primary mouse T cells and localized in the cytoplasm. Using Ribo-Seq in a model T cell line we provide evidence for a role of U2AF26 in activating cytoplasmic steps in gene expression, notably translation. Consistently, an MS2 tethering assay shows that cytoplasmic U2AF26/35 increase translation when localized to the 5'UTR of a model mRNA. This regulation is partially dependent on ZnF1 thus providing a connection between a core splicing factor, the ZnF domains and the regulation of translation. Altogether, our work reveals unexpected functions of U2AF26/35 and their ZnF domains, thereby contributing to a better understanding of their role and regulation in mammalian cells.
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Affiliation(s)
- Olga Herdt
- Institute of Chemistry and Biochemistry, Laboratory of RNA Biochemistry, Freie Universität Berlin , Berlin, Germany
| | - Stefan Reich
- Institute of Biochemistry I, University of Regensburg , Regensburg, Germany
| | - Jan Medenbach
- Institute of Biochemistry I, University of Regensburg , Regensburg, Germany
| | - Bernd Timmermann
- Sequencing Core Facility, Max-Planck-Institute for Molecular Genetics , Berlin, Germany
| | - Didrik Olofsson
- Institute of Chemistry and Biochemistry, Laboratory of RNA Biochemistry, Freie Universität Berlin , Berlin, Germany
| | - Marco Preußner
- Institute of Chemistry and Biochemistry, Laboratory of RNA Biochemistry, Freie Universität Berlin , Berlin, Germany
| | - Florian Heyd
- Institute of Chemistry and Biochemistry, Laboratory of RNA Biochemistry, Freie Universität Berlin , Berlin, Germany
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6
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Differential Interleukin-2 Transcription Kinetics Render Mouse but Not Human T Cells Vulnerable to Splicing Inhibition Early after Activation. Mol Cell Biol 2019; 39:MCB.00035-19. [PMID: 31160491 DOI: 10.1128/mcb.00035-19] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 05/28/2019] [Indexed: 12/24/2022] Open
Abstract
T cells are nodal players in the adaptive immune response against pathogens and malignant cells. Alternative splicing plays a crucial role in T cell activation, which is analyzed mainly at later time points upon stimulation. Here we have discovered a 2-h time window early after stimulation where optimal splicing efficiency or, more generally, gene expression efficiency is crucial for successful T cell activation. Reducing the splicing efficiency at 4 to 6 h poststimulation significantly impaired murine T cell activation, which was dependent on the expression dynamics of the Egr1-Nab2-interleukin-2 (IL-2) pathway. This time window overlaps the time of peak IL-2 de novo transcription, which, we suggest, represents a permissive time window in which decreased splicing (or transcription) efficiency reduces mature IL-2 production, thereby hampering murine T cell activation. Notably, the distinct expression kinetics of the Egr1-Nab2-IL-2 pathway between mouse and human render human T cells refractory to this vulnerability. We propose that the rational temporal modulation of splicing or transcription during peak de novo expression of key effectors can be used to fine-tune stimulation-dependent biological outcomes. Our data also show that critical consideration is required when extrapolating mouse data to the human system in basic and translational research.
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7
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De Bortoli F, Neumann A, Kotte A, Timmermann B, Schüler T, Wahl MC, Loll B, Heyd F. Increased versatility despite reduced molecular complexity: evolution, structure and function of metazoan splicing factor PRPF39. Nucleic Acids Res 2019; 47:5867-5879. [PMID: 30949712 PMCID: PMC6582350 DOI: 10.1093/nar/gkz243] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 03/20/2019] [Accepted: 03/25/2019] [Indexed: 12/18/2022] Open
Abstract
In the yeast U1 snRNP the Prp39/Prp42 heterodimer is essential for early steps of spliceosome assembly. In metazoans no Prp42 ortholog exists, raising the question how the heterodimer is functionally substituted. Here we present the crystal structure of murine PRPF39, which forms a homodimer. Structure-guided point mutations disrupt dimer formation and inhibit splicing, manifesting the homodimer as functional unit. PRPF39 expression is controlled by NMD-inducing alternative splicing in mice and human, suggesting a role in adapting splicing efficiency to cell type specific requirements. A phylogenetic analysis reveals coevolution of shortened U1 snRNA and the absence of Prp42, which correlates with overall splicing complexity in different fungi. While current models correlate the diversity of spliceosomal proteins with splicing complexity, our study highlights a contrary case. We find that organisms with higher splicing complexity have substituted the Prp39/Prp42 heterodimer with a PRPF39 homodimer.
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Affiliation(s)
- Francesca De Bortoli
- Institut für Chemie und Biochemie, RNA Biochemie, Freie Universität Berlin, Takustr. 6, 14195 Berlin, Germany
| | - Alexander Neumann
- Institut für Chemie und Biochemie, RNA Biochemie, Freie Universität Berlin, Takustr. 6, 14195 Berlin, Germany
| | - Ana Kotte
- Institut für Chemie und Biochemie, RNA Biochemie, Freie Universität Berlin, Takustr. 6, 14195 Berlin, Germany
| | - Bernd Timmermann
- Sequencing Core Facility, Max-Planck-Institute for Molecular Genetics, Ihnestraße 63-73, Berlin 14195, Germany
| | - Thomas Schüler
- Institute of Molecular and Clinical Immunology, Medical Faculty, Otto-von-Guericke University, 39120 Magdeburg, Germany
| | - Markus C Wahl
- Institut für Chemie und Biochemie, Strukturbiochemie, Freie Universität Berlin, Takustr. 6, 14195 Berlin, Germany.,Helmholtz-Zentrum Berlin für Materialien und Energie, Macromolecular Crystallography, Albert-Einstein-Straße 15, D-12489 Berlin, Germany
| | - Bernhard Loll
- Institut für Chemie und Biochemie, Strukturbiochemie, Freie Universität Berlin, Takustr. 6, 14195 Berlin, Germany
| | - Florian Heyd
- Institut für Chemie und Biochemie, RNA Biochemie, Freie Universität Berlin, Takustr. 6, 14195 Berlin, Germany
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8
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Neumann A, Schindler M, Olofsson D, Wilhelmi I, Schürmann A, Heyd F. Genome-wide identification of alternative splicing events that regulate protein transport across the secretory pathway. J Cell Sci 2019; 132:jcs.230201. [DOI: 10.1242/jcs.230201] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 03/09/2019] [Indexed: 01/05/2023] Open
Abstract
Alternative splicing (AS) strongly increases proteome diversity and functionality in eukaryotic cells. Protein secretion is a tightly-controlled process, especially in a tissue-specific and differentiation-dependent manner. While previous work has focussed on transcriptional and post-translational regulatory mechanisms, the impact of AS on the secretory pathway remains largely unexplored. Here we integrate a published screen for modulators of protein transport and RNA-Seq analyses to identify over 200 AS events as secretion regulators. We confirm that splicing events along all stages of the secretory pathway regulate the efficiency of membrane trafficking using Morpholinos and CRISPR/Cas9. We furthermore show that these events are highly tissue-specific and adapt the secretory pathway during T-cell activation and adipocyte differentiation. Our data substantially advance the understanding of AS functionality, add a new regulatory layer to a fundamental cell biological process and provide a resource of alternative isoforms that control the secretory pathway.
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Affiliation(s)
- Alexander Neumann
- Freie Universität Berlin, Institute of Chemistry and Biochemistry, Laboratory of RNA Biochemistry, Takustrasse 6, 14195 Berlin, Germany
| | - Magdalena Schindler
- Freie Universität Berlin, Institute of Chemistry and Biochemistry, Laboratory of RNA Biochemistry, Takustrasse 6, 14195 Berlin, Germany
| | - Didrik Olofsson
- Freie Universität Berlin, Institute of Chemistry and Biochemistry, Laboratory of RNA Biochemistry, Takustrasse 6, 14195 Berlin, Germany
| | - Ilka Wilhelmi
- Department of Experimental Diabetology, German Institute of Human Nutrition Potsdam-Rehbrücke (DIfE), 14558 Nuthetal, Germany
| | - Annette Schürmann
- Department of Experimental Diabetology, German Institute of Human Nutrition Potsdam-Rehbrücke (DIfE), 14558 Nuthetal, Germany
| | - Florian Heyd
- Freie Universität Berlin, Institute of Chemistry and Biochemistry, Laboratory of RNA Biochemistry, Takustrasse 6, 14195 Berlin, Germany
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9
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Li G, Huang M, Cai Y, Yang Y, Sun X, Ke Y. Circ-U2AF1 promotes human glioma via derepressing neuro-oncological ventral antigen 2 by sponging hsa-miR-7-5p. J Cell Physiol 2018; 234:9144-9155. [PMID: 30341906 DOI: 10.1002/jcp.27591] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 09/18/2018] [Indexed: 12/14/2022]
Abstract
The prognosis for human glioma, a malignant tumor of the central nervous system, is poor due to its rapid growth, genetic heterogeneity, and inadequate understanding of its underlying molecular mechanisms. Circular RNAs composed of exonic sequences, represent an understudied form of noncoding RNAs (ncRNAs) that was discovered more than a decade ago, function as microRNA sponges. We aimed to assess the relationship between circ-U2AF1 (CircRNA ID: hsa_circ_0061868) and hsa-mir-7-5p and examine their effects on proliferation, apoptosis, and the metastatic phenotype of glioma cells regulated by neuro-oncological ventral antigen 2 (NOVA2). We found that the expression levels of circ-U2AF1 and NOVA2 were upregulated, while hsa-miR-7-5p was downregulated in human glioma tissues and glioma cell lines. Our data and bioinformatic analysis indicated the association of these molecules with glioma grade, a positive correlation between circ-U2AF1 and NOVA2 expression levels and a negative correlation of hsa-miR-7-5p with both circ-U2AF1 and NOVA2, respectively. In addition, silencing of circ-U2AF1 expression resulted in increased hsa-miR-7-5p expression and decreased NOVA2 expression both in vitro and in vivo. Luciferase assay confirmed hsa-miR-7-5p as a direct target of circ-U2AF1 and NOVA2 as a direct target of hsa-miR-7-5p. Functionally, silencing of circ-U2AF1 inhibits glioma development by repressing NOVA2 via upregulating hsa-miR-7-5p both in vitro and in vivo. Thus, we assumed that circ-U2AF1 promotes glioma malignancy via derepressing NOVA2 by sponging hsa-miR-7-5p. Taken together, we suggest that circ-U2AF1 can be a prognostic biomarker and the circ-U2AF1/hsa-miR-7-5p/NOVA2 regulatory pathway may be a novel therapeutic target for treating gliomas.
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Affiliation(s)
- Guoxiong Li
- Department of Neurosurgery, Zhujiang Hospital, Southern Medical University, Guangzhou, China.,The National Key Clinical Specialty, Engineering Technology Research Center of Education Ministry of China, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, Guangzhou, China.,Department of Neurosurgery, People's Hospital of Shiyan, Shenzhen, China
| | - Min Huang
- Department of Neurosurgery, Zhujiang Hospital, Southern Medical University, Guangzhou, China.,The National Key Clinical Specialty, Engineering Technology Research Center of Education Ministry of China, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, Guangzhou, China
| | - Yingqian Cai
- Department of Neurosurgery, Zhujiang Hospital, Southern Medical University, Guangzhou, China.,The National Key Clinical Specialty, Engineering Technology Research Center of Education Ministry of China, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, Guangzhou, China
| | - Yuantao Yang
- Department of Neurosurgery, Zhujiang Hospital, Southern Medical University, Guangzhou, China.,The National Key Clinical Specialty, Engineering Technology Research Center of Education Ministry of China, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, Guangzhou, China
| | - Xinlin Sun
- Department of Neurosurgery, Zhujiang Hospital, Southern Medical University, Guangzhou, China.,The National Key Clinical Specialty, Engineering Technology Research Center of Education Ministry of China, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, Guangzhou, China
| | - Yiquan Ke
- Department of Neurosurgery, Zhujiang Hospital, Southern Medical University, Guangzhou, China.,The National Key Clinical Specialty, Engineering Technology Research Center of Education Ministry of China, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, Guangzhou, China
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10
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Goldammer G, Neumann A, Strauch M, Müller-McNicoll M, Heyd F, Preußner M. Characterization of cis-acting elements that control oscillating alternative splicing. RNA Biol 2018; 15:1081-1092. [PMID: 30200840 DOI: 10.1080/15476286.2018.1502587] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Alternative splicing (AS) in response to changing external conditions often requires alterations in the ability of sequence-specific RNA-binding proteins to bind to cis-acting sequences in their target pre-mRNA. While daily oscillations in AS events have been described in several organisms, cis-acting sequences that control time of the day-dependent AS remain largely elusive. Here we define cis-regulatory RNA elements that control body-temperature driven rhythmic AS using the mouse U2af26 gene as a model system. We identify a complex network of cis-regulatory sequences that regulate AS of U2af26, and show that the activity of two enhancer elements is necessary for oscillating AS. A minigene comprising these U2af26 regions recapitulates rhythmic splicing of the endogenous gene, which is controlled through temperature-regulated SR protein phosphorylation. Mutagenesis of the minigene delineates the cis-acting enhancer element for SRSF2 within exon 6 to single nucleotide resolution and reveals that the combined activity of SRSF2 and SRSF7 is required for oscillating U2af26 AS. By combining RNA-Seq with an siRNA screen and individual-nucleotide resolution cross-linking and immunoprecipitation (iCLIP), we identify a complex network of SR proteins that globally controls temperature-dependent rhythmic AS, with the direction of splicing depending on the position of the cis-acting elements. Together, we provide detailed insights into the sequence requirements that allow trans-acting factors to generate daily rhythms in AS.
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Affiliation(s)
- Gesine Goldammer
- a Laboratory of RNA Biochemistry , Freie Universität Berlin, Institute of Chemistry and Biochemistry , Berlin , Germany
| | - Alexander Neumann
- a Laboratory of RNA Biochemistry , Freie Universität Berlin, Institute of Chemistry and Biochemistry , Berlin , Germany
| | - Miriam Strauch
- a Laboratory of RNA Biochemistry , Freie Universität Berlin, Institute of Chemistry and Biochemistry , Berlin , Germany
| | - Michaela Müller-McNicoll
- b Cluster of Excellence Macromolecular Complexes, Institute of Cell Biology and Neuroscience , Goethe University Frankfurt , Frankfurt am Main , Germany
| | - Florian Heyd
- a Laboratory of RNA Biochemistry , Freie Universität Berlin, Institute of Chemistry and Biochemistry , Berlin , Germany
| | - Marco Preußner
- a Laboratory of RNA Biochemistry , Freie Universität Berlin, Institute of Chemistry and Biochemistry , Berlin , Germany
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11
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Finci LI, Zhang X, Huang X, Zhou Q, Tsai J, Teng T, Agrawal A, Chan B, Irwin S, Karr C, Cook A, Zhu P, Reynolds D, Smith PG, Fekkes P, Buonamici S, Larsen NA. The cryo-EM structure of the SF3b spliceosome complex bound to a splicing modulator reveals a pre-mRNA substrate competitive mechanism of action. Genes Dev 2018; 32:309-320. [PMID: 29491137 PMCID: PMC5859971 DOI: 10.1101/gad.311043.117] [Citation(s) in RCA: 78] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Accepted: 02/07/2018] [Indexed: 12/16/2022]
Abstract
In this study, Finci et. al. present the cryo-EM structure of the SF3b subcomplex (SF3B1, SF3B3, PHF5A, and SF3B5), part of the U2 snRNP, bound to E7107 at 3.95 A. The structure suggests a model in which splicing modulators interfere with branch point adenosine recognition and supports a substrate competitive mechanism of action. Somatic mutations in spliceosome proteins lead to dysregulated RNA splicing and are observed in a variety of cancers. These genetic aberrations may offer a potential intervention point for targeted therapeutics. SF3B1, part of the U2 small nuclear RNP (snRNP), is targeted by splicing modulators, including E7107, the first to enter clinical trials, and, more recently, H3B-8800. Modulating splicing represents a first-in-class opportunity in drug discovery, and elucidating the structural basis for the mode of action opens up new possibilities for structure-based drug design. Here, we present the cryogenic electron microscopy (cryo-EM) structure of the SF3b subcomplex (SF3B1, SF3B3, PHF5A, and SF3B5) bound to E7107 at 3.95 Å. This structure shows that E7107 binds in the branch point adenosine-binding pocket, forming close contacts with key residues that confer resistance upon mutation: SF3B1R1074H and PHF5AY36C. The structure suggests a model in which splicing modulators interfere with branch point adenosine recognition and supports a substrate competitive mechanism of action (MOA). Using several related chemical probes, we validate the pose of the compound and support their substrate competitive MOA by comparing their activity against both strong and weak pre-mRNA substrates. Finally, we present functional data and structure–activity relationship (SAR) on the PHF5AR38C mutation that sensitizes cells to some chemical probes but not others. Developing small molecule splicing modulators represents a promising therapeutic approach for a variety of diseases, and this work provides a significant step in enabling structure-based drug design for these elaborate natural products. Importantly, this work also demonstrates that the utilization of cryo-EM in drug discovery is coming of age.
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Affiliation(s)
- Lorenzo I Finci
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Xiaofeng Zhang
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Xiuliang Huang
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Qiang Zhou
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Jennifer Tsai
- H3 Biomedicine, Inc., Cambridge, Massachusetts 02139, USA
| | - Teng Teng
- H3 Biomedicine, Inc., Cambridge, Massachusetts 02139, USA
| | - Anant Agrawal
- H3 Biomedicine, Inc., Cambridge, Massachusetts 02139, USA
| | - Betty Chan
- H3 Biomedicine, Inc., Cambridge, Massachusetts 02139, USA
| | - Sean Irwin
- H3 Biomedicine, Inc., Cambridge, Massachusetts 02139, USA
| | - Craig Karr
- H3 Biomedicine, Inc., Cambridge, Massachusetts 02139, USA
| | - Andrew Cook
- H3 Biomedicine, Inc., Cambridge, Massachusetts 02139, USA
| | - Ping Zhu
- H3 Biomedicine, Inc., Cambridge, Massachusetts 02139, USA
| | | | - Peter G Smith
- H3 Biomedicine, Inc., Cambridge, Massachusetts 02139, USA
| | - Peter Fekkes
- H3 Biomedicine, Inc., Cambridge, Massachusetts 02139, USA
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