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Pascal C, Zonszain J, Hameiri O, Gargi-Levi C, Lev-Maor G, Tammer L, Levy T, Tarabeih A, Roy VR, Ben-Salmon S, Elbaz L, Eid M, Hakim T, Abu Rabe'a S, Shalev N, Jordan A, Meshorer E, Ast G. Human histone H1 variants impact splicing outcome by controlling RNA polymerase II elongation. Mol Cell 2023; 83:3801-3817.e8. [PMID: 37922872 DOI: 10.1016/j.molcel.2023.10.003] [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] [Received: 03/21/2023] [Revised: 08/17/2023] [Accepted: 10/05/2023] [Indexed: 11/07/2023]
Abstract
Histones shape chromatin structure and the epigenetic landscape. H1, the most diverse histone in the human genome, has 11 variants. Due to the high structural similarity between the H1s, their unique functions in transferring information from the chromatin to mRNA-processing machineries have remained elusive. Here, we generated human cell lines lacking up to five H1 subtypes, allowing us to characterize the genomic binding profiles of six H1 variants. Most H1s bind to specific sites, and binding depends on multiple factors, including GC content. The highly expressed H1.2 has a high affinity for exons, whereas H1.3 binds intronic sequences. H1s are major splicing regulators, especially of exon skipping and intron retention events, through their effects on the elongation of RNA polymerase II (RNAPII). Thus, H1 variants determine splicing fate by modulating RNAPII elongation.
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Affiliation(s)
- Corina Pascal
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Jonathan Zonszain
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Ofir Hameiri
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Chen Gargi-Levi
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Galit Lev-Maor
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Luna Tammer
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Tamar Levy
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Anan Tarabeih
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Vanessa Rachel Roy
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Stav Ben-Salmon
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Liraz Elbaz
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Mireille Eid
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Tamar Hakim
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Salima Abu Rabe'a
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Nana Shalev
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Albert Jordan
- Instituto de Biologia Molecular de Barcelona (IBMB-CSIC), Carrer de Baldiri Reixac, 15, 08028 Barcelona, Spain
| | - Eran Meshorer
- Department of Genetics, The Alexander Silberman Institute of Life Sciences, Jerusalem 91904, Israel; Edmond and Lily Center for Brain Sciences (ELSC), The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Gil Ast
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel.
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2
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Karlebach G, Steinhaus R, Danis D, Devoucoux M, Anczuków O, Sheynkman G, Seelow D, Robinson PN. Alternative splicing is coupled to gene expression in a subset of variably expressed genes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.13.544742. [PMID: 37398049 PMCID: PMC10312658 DOI: 10.1101/2023.06.13.544742] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Numerous factors regulate alternative splicing of human genes at a co-transcriptional level. However, how alternative splicing depends on the regulation of gene expression is poorly understood. We leveraged data from the Genotype-Tissue Expression (GTEx) project to show a significant association of gene expression and splicing for 6874 (4.9%) of 141,043 exons in 1106 (13.3%) of 8314 genes with substantially variable expression in ten GTEx tissues. About half of these exons demonstrate higher inclusion with higher gene expression, and half demonstrate higher exclusion, with the observed direction of coupling being highly consistent across different tissues and in external datasets. The exons differ with respect to sequence characteristics, enriched sequence motifs, RNA polymerase II binding, and inferred transcription rate of downstream introns. The exons were enriched for hundreds of isoform-specific Gene Ontology annotations, suggesting that the coupling of expression and alternative splicing described here may provide an important gene regulatory mechanism that might be used in a variety of biological contexts. In particular, higher inclusion exons could play an important role during cell division.
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Affiliation(s)
- Guy Karlebach
- The Jackson Laboratory for Genomic Medicine, Farmington, CT 06032, USA
| | - Robin Steinhaus
- Exploratory Diagnostic Sciences, Berlin Institute of Health, 10117 Berlin, Germany
- Institute of Medical Genetics and Human Genetics, Charité - Universitätsmedizin Berlin, corporate member of Freie Universitat Berlin and Humboldt-Universität zu Berlin, 13353 10117 Berlin, Germany
| | - Daniel Danis
- The Jackson Laboratory for Genomic Medicine, Farmington, CT 06032, USA
| | - Maeva Devoucoux
- The Jackson Laboratory for Genomic Medicine, Farmington, CT 06032, USA
| | - Olga Anczuków
- The Jackson Laboratory for Genomic Medicine, Farmington, CT 06032, USA
- Department of Genetics and Genome Sciences, UConn Health, Farmington, CT 06032, USA
- Institute for Systems Genomics, University of Connecticut, Farmington, CT 06032, USA
| | - Gloria Sheynkman
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 22903, USA
| | - Dominik Seelow
- Exploratory Diagnostic Sciences, Berlin Institute of Health, 10117 Berlin, Germany
- Institute of Medical Genetics and Human Genetics, Charité - Universitätsmedizin Berlin, corporate member of Freie Universitat Berlin and Humboldt-Universität zu Berlin, 13353 10117 Berlin, Germany
| | - Peter N Robinson
- The Jackson Laboratory for Genomic Medicine, Farmington, CT 06032, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 22903, USA
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3
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Imbriano C, Belluti S. Histone Marks-Dependent Effect on Alternative Splicing: New Perspectives for Targeted Splicing Modulation in Cancer? Int J Mol Sci 2022; 23:ijms23158304. [PMID: 35955433 PMCID: PMC9368390 DOI: 10.3390/ijms23158304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 07/23/2022] [Accepted: 07/25/2022] [Indexed: 11/16/2022] Open
Abstract
Alternative splicing (AS) is a tightly regulated mechanism that generates the complex human proteome from a small number of genes. Cis-regulatory RNA motifs in exons and introns control AS, recruiting positive and negative trans-acting splicing regulators. At a higher level, chromatin affects splicing events. Growing evidence indicates that the popular histone code hypothesis can be extended to RNA-level processes, such as AS. In addition to nucleosome positioning, which can generate transcriptional barriers to shape the final splicing outcome, histone post-translational modifications can contribute to the detailed regulation of single exon inclusion/exclusion. A histone-based system can identify alternatively spliced chromatin stretches, affecting RNAPII elongation locally or recruiting splicing components via adaptor complexes. In tumor cells, several mechanisms trigger misregulated AS events and produce cancer-associated transcripts. On a genome-wide level, aberrant AS can be the consequence of dysfunctional epigenetic splicing code, including altered enrichment in histone post-translational modifications. This review describes the main findings related to the effect of histone modifications and variants on splicing outcome and how a dysfunctional epigenetic splicing code triggers aberrant AS in cancer. In addition, it highlights recent advances in programmable DNA-targeting technologies and their possible application for AS targeted epigenetic modulation.
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4
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Gnan S, Matelot M, Weiman M, Arnaiz O, Guérin F, Sperling L, Bétermier M, Thermes C, Chen CL, Duharcourt S. GC content, but not nucleosome positioning, directly contributes to intron splicing efficiency in Paramecium. Genome Res 2022; 32:699-709. [PMID: 35264448 PMCID: PMC8997360 DOI: 10.1101/gr.276125.121] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Accepted: 02/14/2022] [Indexed: 11/24/2022]
Abstract
Eukaryotic genes are interrupted by introns that must be accurately spliced from mRNA precursors. With an average length of 25 nt, the more than 90,000 introns of Paramecium tetraurelia stand among the shortest introns reported in eukaryotes. The mechanisms specifying the correct recognition of these tiny introns remain poorly understood. Splicing can occur cotranscriptionally, and it has been proposed that chromatin structure might influence splice site recognition. To investigate the roles of nucleosome positioning in intron recognition, we determined the nucleosome occupancy along the P. tetraurelia genome. We show that P. tetraurelia displays a regular nucleosome array with a nucleosome repeat length of ∼151 bp, among the smallest periodicities reported. Our analysis has revealed that introns are frequently associated with inter-nucleosomal DNA, pointing to an evolutionary constraint favoring introns at the AT-rich nucleosome edge sequences. Using accurate splicing efficiency data from cells depleted for nonsense-mediated decay effectors, we show that introns located at the edge of nucleosomes display higher splicing efficiency than those at the center. However, multiple regression analysis indicates that the low GC content of introns, rather than nucleosome positioning, is associated with high splicing efficiency. Our data reveal a complex link between GC content, nucleosome positioning, and intron evolution in Paramecium.
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Affiliation(s)
- Stefano Gnan
- Institut Curie, Université PSL, Sorbonne Université, CNRS UMR3244, Dynamics of Genetic Information, Paris, 75005 France
| | - Mélody Matelot
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
| | - Marion Weiman
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France
| | - Olivier Arnaiz
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France
| | - Frédéric Guérin
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
| | - Linda Sperling
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France
| | - Mireille Bétermier
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France
| | - Claude Thermes
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France
| | - Chun-Long Chen
- Institut Curie, Université PSL, Sorbonne Université, CNRS UMR3244, Dynamics of Genetic Information, Paris, 75005 France
| | - Sandra Duharcourt
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
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5
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Segelle A, Núñez-Álvarez Y, Oldfield AJ, Webb KM, Voigt P, Luco RF. Histone marks regulate the epithelial-to-mesenchymal transition via alternative splicing. Cell Rep 2022; 38:110357. [PMID: 35172149 DOI: 10.1016/j.celrep.2022.110357] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 09/20/2021] [Accepted: 01/19/2022] [Indexed: 12/15/2022] Open
Abstract
Histone modifications impact final splicing decisions. However, there is little evidence of the driving role of these marks in inducing cell-specific splicing changes. Using CRISPR epigenome editing tools, we show in an epithelial-to-mesenchymal cell reprogramming system (epithelial-to-mesenchymal transition [EMT]) that a single change in H3K27ac or H3K27me3 levels right at the alternatively spliced exon is necessary and sufficient to induce a splicing change capable of recapitulating important aspects of EMT, such as cell motility and invasiveness. This histone-mark-dependent splicing effect is highly dynamic and mediated by direct recruitment of the splicing regulator PTB to its RNA binding sites. These results support a role for H3K27 marks in inducing a change in the cell's phenotype via regulation of alternative splicing. We propose the dynamic nature of chromatin as a rapid and reversible mechanism to coordinate the splicing response to cell-extrinsic cues, such as induction of EMT.
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Affiliation(s)
- Alexandre Segelle
- Institute of Human Genetics, University of Montpellier, Centre National de la Recherche Scientifique, Montpellier, France
| | - Yaiza Núñez-Álvarez
- Institute of Human Genetics, University of Montpellier, Centre National de la Recherche Scientifique, Montpellier, France
| | - Andrew J Oldfield
- Institute of Human Genetics, University of Montpellier, Centre National de la Recherche Scientifique, Montpellier, France
| | - Kimberly M Webb
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Philipp Voigt
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Reini F Luco
- Institute of Human Genetics, University of Montpellier, Centre National de la Recherche Scientifique, Montpellier, France.
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He K, Feng Y, An S, Liu F, Xiang G. Integrative epigenomic profiling reveal AP-1 is a key regulator in intrahepatich cholangiocarcinoma. Genomics 2021; 114:241-252. [PMID: 34942351 DOI: 10.1016/j.ygeno.2021.12.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2020] [Revised: 04/19/2021] [Accepted: 12/14/2021] [Indexed: 01/14/2023]
Abstract
Intrahepatic cholangiocarcinoma (ICC) is a malignant tumor with poor prognosis while its mechanisms of pathogenesis remain elusive. In this study, we performed systemic epigenomic and transcriptomic profiling via MNase-seq, ChIP-seq and RNA-seq in normal cholangiocyte and ICC cell lines. We showed that active histone modifications (H3K4me3, H3K4me1 and H3K27ac) were less enriched on cancer-related genes in ICC cell lines compared to control. The region of different histone modification patterns is enrichment in sites of AP-1 motif. Subsequent analysis showed that ICC had different nucleosome occupancy in differentially expressed genes compared to a normal cell line. Furthermore, we found that AP-1 plays a key role in ICC and regulates ICC-related genes through its AP-1 binding site. This study is the first report showing the global features of histone modification, transcript, and nucleosome profiles in ICC; we also show that the transcription factor AP-1 might be a key target gene in ICC.
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Affiliation(s)
- Ke He
- Department of General Surgery, Guangdong Second Provincial General Hospital, Guangzhou 510317, China; Department of Biochemistry, Zhongshan School of Medicine; Center for Stem Cell Biology and Tissue Engineering, Key laboratory of ministry of education, Sun Yat-sen University, Guangzhou 510080, China
| | - Yuliang Feng
- Botnar Research Centre, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, OX37LD, United Kingdom
| | - Sanqi An
- Department of General Surgery, Guangdong Second Provincial General Hospital, Guangzhou 510317, China; Department of Biochemistry, Zhongshan School of Medicine; Center for Stem Cell Biology and Tissue Engineering, Key laboratory of ministry of education, Sun Yat-sen University, Guangzhou 510080, China
| | - Fei Liu
- Department of General Surgery, Guangdong Second Provincial General Hospital, Guangzhou 510317, China
| | - Guoan Xiang
- Department of General Surgery, Guangdong Second Provincial General Hospital, Guangzhou 510317, China.
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7
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Ranjan M, Lee O, Cottone G, Mirzaei Mehrabad E, Spike BT, Zeng Z, Yadav S, Chatterton R, Kim JJ, Clare SE, Khan SA. Progesterone receptor antagonists reverse stem cell expansion and the paracrine effectors of progesterone action in the mouse mammary gland. Breast Cancer Res 2021; 23:78. [PMID: 34344445 PMCID: PMC8330021 DOI: 10.1186/s13058-021-01455-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 07/09/2021] [Indexed: 12/13/2022] Open
Abstract
Background The ovarian hormones estrogen and progesterone (EP) are implicated in breast cancer causation. A specific consequence of progesterone exposure is the expansion of the mammary stem cell (MSC) and luminal progenitor (LP) compartments. We hypothesized that this effect, and its molecular facilitators, could be abrogated by progesterone receptor (PR) antagonists administered in a mouse model. Methods Ovariectomized FVB mice were randomized to 14 days of treatment: sham, EP, EP + telapristone (EP + TPA), EP + mifepristone (EP + MFP). Mice were then sacrificed, mammary glands harvested, and mammary epithelial cell lineages separated by flow cytometry using cell surface markers. RNA from each lineage was sequenced and differential gene expression was analyzed using DESeq. Quantitative PCR was performed to confirm the candidate genes discovered in RNA seq. ANOVA with Tukey post hoc analysis was performed to compare relative expression. Alternative splicing events were examined using the rMATs multivariate analysis tool. Results Significant increases in the MSC and luminal mature (LM) cell fractions were observed following EP treatment compared to control (p < 0.01 and p < 0.05, respectively), whereas the LP fraction was significantly reduced (p < 0.05). These hormone-induced effects were reversed upon exposure to TPA and MFP (p < 0.01 for both). Gene Ontology analysis of RNA-sequencing data showed EP-induced enrichment of several pathways, with the largest effect on Wnt signaling in MSC, significantly repressed by PR inhibitors. In LP cells, significant induction of Wnt4 and Rankl, and Wnt pathway intermediates Lrp2 and Axin2 (confirmed by qRTPCR) were reversed by TPA and MFP (p < 0.0001). Downstream signaling intermediates of these pathways (Lrp5, Mmp7) showed similar effects. Expression of markers of epithelial-mesenchymal transition (Cdh1, Cdh3) and the induction of EMT regulators (Zeb1, Zeb2, Gli3, Snai1, and Ptch2) were significantly responsive to progesterone. EP treatment was associated with large-scale alternative splicing events, with an enrichment of motifs associated with Srsf, Esrp, and Rbfox families. Exon skipping was observed in Cdh1, Enah, and Brd4. Conclusions PR inhibition reverses known tumorigenic pathways in the mammary gland and suppresses a previously unknown effect of progesterone on RNA splicing events. In total, our results strengthen the case for reconsideration of PR inhibitors for breast cancer prevention. Supplementary Information The online version contains supplementary material available at 10.1186/s13058-021-01455-2.
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Affiliation(s)
- Manish Ranjan
- Department of Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Oukseub Lee
- Department of Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Gannon Cottone
- Department of Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | | | - Benjamin T Spike
- Huntsman Cancer Institute, Department of Oncological Sciences, University of Utah, Salt Lake City, UT, 84112, USA
| | - Zexian Zeng
- Division of Health and Biomedical Informatics, Department of Preventive Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Shivangi Yadav
- Department of Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Robert Chatterton
- Department of Obstetrics and Gynecology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA.,Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Chicago, IL, 60611, USA
| | - J Julie Kim
- Department of Obstetrics and Gynecology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA.,Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Chicago, IL, 60611, USA
| | - Susan E Clare
- Department of Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA.
| | - Seema A Khan
- Department of Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA. .,Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Chicago, IL, 60611, USA.
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8
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Jabre I, Chaudhary S, Guo W, Kalyna M, Reddy ASN, Chen W, Zhang R, Wilson C, Syed NH. Differential nucleosome occupancy modulates alternative splicing in Arabidopsis thaliana. THE NEW PHYTOLOGIST 2021; 229:1937-1945. [PMID: 33135169 DOI: 10.1111/nph.17062] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 10/24/2020] [Indexed: 05/13/2023]
Abstract
Alternative splicing (AS) is a major gene regulatory mechanism in plants. Recent evidence supports co-transcriptional splicing in plants, hence the chromatin state can impact AS. However, how dynamic changes in the chromatin state such as nucleosome occupancy influence the cold-induced AS remains poorly understood. Here, we generated transcriptome (RNA-Seq) and nucleosome positioning (MNase-Seq) data for Arabidopsis thaliana to understand how nucleosome positioning modulates cold-induced AS. Our results show that characteristic nucleosome occupancy levels are strongly associated with the type and abundance of various AS events under normal and cold temperature conditions in Arabidopsis. Intriguingly, exitrons, alternatively spliced internal regions of protein-coding exons, exhibit distinctive nucleosome positioning pattern compared to other alternatively spliced regions. Likewise, nucleosome patterns differ between exitrons and retained introns, pointing to their distinct regulation. Collectively, our data show that characteristic changes in nucleosome positioning modulate AS in plants in response to cold.
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Affiliation(s)
- Ibtissam Jabre
- School of Human and Life Sciences, Canterbury Christ Church University, Canterbury, CT1 1QU, UK
- School of Biosciences and Medicine, University of Surrey, Guildford, GU2 7XH, UK
| | - Saurabh Chaudhary
- School of Human and Life Sciences, Canterbury Christ Church University, Canterbury, CT1 1QU, UK
- Cardiff School of Biosciences, Cardiff University, Cardiff, CF10 3AX, UK
| | - Wenbin Guo
- Computational Sciences, The James Hutton Institute, Dundee, DD2 5DA, UK
| | - Maria Kalyna
- Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences - BOKU, Muthgasse 18, 1190, Vienna, Austria
| | - Anireddy S N Reddy
- Department of Biology and Program in Cell and Molecular Biology, Colorado State University, Fort Collins, CO, 80523-1878, USA
| | - Weizhong Chen
- Department of Molecular Biology & Genetics, Cornell University, Ithaca, NY, 14853-2703, USA
| | - Runxuan Zhang
- Computational Sciences, The James Hutton Institute, Dundee, DD2 5DA, UK
| | - Cornelia Wilson
- School of Human and Life Sciences, Canterbury Christ Church University, Canterbury, CT1 1QU, UK
| | - Naeem H Syed
- School of Human and Life Sciences, Canterbury Christ Church University, Canterbury, CT1 1QU, UK
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9
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Agirre E, Oldfield AJ, Bellora N, Segelle A, Luco RF. Splicing-associated chromatin signatures: a combinatorial and position-dependent role for histone marks in splicing definition. Nat Commun 2021; 12:682. [PMID: 33514745 PMCID: PMC7846797 DOI: 10.1038/s41467-021-20979-x] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 01/05/2021] [Indexed: 12/14/2022] Open
Abstract
Alternative splicing relies on the combinatorial recruitment of splicing regulators to specific RNA binding sites. Chromatin has been shown to impact this recruitment. However, a limited number of histone marks have been studied at a global level. In this work, a machine learning approach, applied to extensive epigenomics datasets in human H1 embryonic stem cells and IMR90 foetal fibroblasts, has identified eleven chromatin modifications that differentially mark alternatively spliced exons depending on the level of exon inclusion. These marks act in a combinatorial and position-dependent way, creating characteristic splicing-associated chromatin signatures (SACS). In support of a functional role for SACS in coordinating splicing regulation, changes in the alternative splicing of SACS-marked exons between ten different cell lines correlate with changes in SACS enrichment levels and recruitment of the splicing regulators predicted by RNA motif search analysis. We propose the dynamic nature of chromatin modifications as a mechanism to rapidly fine-tune alternative splicing when necessary. Chromatin is known to regulate splicing by modulating recruitment of splicing factors. Using machine learning approaches, the authors have underlined a chromatin code for alternative splicing regulation that is conserved amongst cell lines.
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Affiliation(s)
- E Agirre
- Institute of Human Genetics, UMR9002 CNRS-University of Montpellier, 34000, Montpellier, France.,Laboratory of Molecular Neurobiology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - A J Oldfield
- Institute of Human Genetics, UMR9002 CNRS-University of Montpellier, 34000, Montpellier, France
| | - N Bellora
- Institute of Nuclear Technologies for Health (INTECNUS), National Scientific and Technical Research Council (CONICET), Bariloche, 8400, Argentina
| | - A Segelle
- Institute of Human Genetics, UMR9002 CNRS-University of Montpellier, 34000, Montpellier, France
| | - R F Luco
- Institute of Human Genetics, UMR9002 CNRS-University of Montpellier, 34000, Montpellier, France.
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10
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Monteuuis G, Wong JJL, Bailey CG, Schmitz U, Rasko JEJ. The changing paradigm of intron retention: regulation, ramifications and recipes. Nucleic Acids Res 2020; 47:11497-11513. [PMID: 31724706 PMCID: PMC7145568 DOI: 10.1093/nar/gkz1068] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 10/04/2019] [Accepted: 10/30/2019] [Indexed: 12/13/2022] Open
Abstract
Intron retention (IR) is a form of alternative splicing that has long been neglected in mammalian systems although it has been studied for decades in non-mammalian species such as plants, fungi, insects and viruses. It was generally assumed that mis-splicing, leading to the retention of introns, would have no physiological consequence other than reducing gene expression by nonsense-mediated decay. Relatively recent landmark discoveries have highlighted the pivotal role that IR serves in normal and disease-related human biology. Significant technical hurdles have been overcome, thereby enabling the robust detection and quantification of IR. Still, relatively little is known about the cis- and trans-acting modulators controlling this phenomenon. The fate of an intron to be, or not to be, retained in the mature transcript is the direct result of the influence exerted by numerous intrinsic and extrinsic factors at multiple levels of regulation. These factors have altered current biological paradigms and provided unexpected insights into the transcriptional landscape. In this review, we discuss the regulators of IR and methods to identify them. Our focus is primarily on mammals, however, we broaden the scope to non-mammalian organisms in which IR has been shown to be biologically relevant.
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Affiliation(s)
- Geoffray Monteuuis
- Gene and Stem Cell Therapy Program Centenary Institute, The University of Sydney, Camperdown, Australia
| | - Justin J L Wong
- Faculty of Medicine and Health, The University of Sydney, NSW 2006, Australia.,Epigenetics and RNA Biology Program Centenary Institute, The University of Sydney, Camperdown, Australia
| | - Charles G Bailey
- Gene and Stem Cell Therapy Program Centenary Institute, The University of Sydney, Camperdown, Australia.,Faculty of Medicine and Health, The University of Sydney, NSW 2006, Australia
| | - Ulf Schmitz
- Gene and Stem Cell Therapy Program Centenary Institute, The University of Sydney, Camperdown, Australia.,Faculty of Medicine and Health, The University of Sydney, NSW 2006, Australia.,Computational Biomedicine Laboratory Centenary Institute, The University of Sydney, Camperdown, Australia
| | - John E J Rasko
- Gene and Stem Cell Therapy Program Centenary Institute, The University of Sydney, Camperdown, Australia.,Faculty of Medicine and Health, The University of Sydney, NSW 2006, Australia.,Cell and Molecular Therapies, Royal Prince Alfred Hospital, Camperdown, Australia
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11
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Martí-Gómez C, Lara-Pezzi E, Sánchez-Cabo F. dSreg: a Bayesian model to integrate changes in splicing and RNA-binding protein activity. Bioinformatics 2020; 36:2134-2141. [PMID: 31834368 PMCID: PMC7141860 DOI: 10.1093/bioinformatics/btz915] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 09/09/2019] [Accepted: 12/10/2019] [Indexed: 12/19/2022] Open
Abstract
MOTIVATION Alternative splicing (AS) is an important mechanism in the generation of transcript diversity across mammals. AS patterns are dynamically regulated during development and in response to environmental changes. Defects or perturbations in its regulation may lead to cancer or neurological disorders, among other pathological conditions. The regulatory mechanisms controlling AS in a given biological context are typically inferred using a two-step framework: differential AS analysis followed by enrichment methods. These strategies require setting rather arbitrary thresholds and are prone to error propagation along the analysis. RESULTS To overcome these limitations, we propose dSreg, a Bayesian model that integrates RNA-seq with data from regulatory features, e.g. binding sites of RNA-binding proteins. dSreg identifies the key underlying regulators controlling AS changes and quantifies their activity while simultaneously estimating the changes in exon inclusion rates. dSreg increased both the sensitivity and the specificity of the identified AS changes in simulated data, even at low read coverage. dSreg also showed improved performance when analyzing a collection of knock-down RNA-binding proteins' experiments from ENCODE, as opposed to traditional enrichment methods, such as over-representation analysis and gene set enrichment analysis. dSreg opens the possibility to integrate a large amount of readily available RNA-seq datasets at low coverage for AS analysis and allows more cost-effective RNA-seq experiments. AVAILABILITY AND IMPLEMENTATION dSreg was implemented in python using stan and is freely available to the community at https://bitbucket.org/cmartiga/dsreg. SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Carlos Martí-Gómez
- Molecular Regulation of Heart Failure (CMG and ELP); Bioinformatics Unit (FSC), Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid 28029, Spain
| | - Enrique Lara-Pezzi
- Molecular Regulation of Heart Failure (CMG and ELP); Bioinformatics Unit (FSC), Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid 28029, Spain
| | - Fátima Sánchez-Cabo
- Molecular Regulation of Heart Failure (CMG and ELP); Bioinformatics Unit (FSC), Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid 28029, Spain
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12
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Magomedova L, Tiefenbach J, Zilberman E, Le Billan F, Voisin V, Saikali M, Boivin V, Robitaille M, Gueroussov S, Irimia M, Ray D, Patel R, Xu C, Jeyasuria P, Bader GD, Hughes TR, Morris QD, Scott MS, Krause H, Angers S, Blencowe BJ, Cummins CL. ARGLU1 is a transcriptional coactivator and splicing regulator important for stress hormone signaling and development. Nucleic Acids Res 2019; 47:2856-2870. [PMID: 30698747 PMCID: PMC6451108 DOI: 10.1093/nar/gkz010] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2017] [Revised: 12/21/2018] [Accepted: 01/04/2019] [Indexed: 12/17/2022] Open
Abstract
Stress hormones bind and activate the glucocorticoid receptor (GR) in many tissues including the brain. We identified arginine and glutamate rich 1 (ARGLU1) in a screen for new modulators of glucocorticoid signaling in the CNS. Biochemical studies show that the glutamate rich C-terminus of ARGLU1 coactivates multiple nuclear receptors including the glucocorticoid receptor (GR) and the arginine rich N-terminus interacts with splicing factors and binds to RNA. RNA-seq of neural cells depleted of ARGLU1 revealed significant changes in the expression and alternative splicing of distinct genes involved in neurogenesis. Loss of ARGLU1 is embryonic lethal in mice, and knockdown in zebrafish causes neurodevelopmental and heart defects. Treatment with dexamethasone, a GR activator, also induces changes in the pattern of alternatively spliced genes, many of which were lost when ARGLU1 was absent. Importantly, the genes found to be alternatively spliced in response to glucocorticoid treatment were distinct from those under transcriptional control by GR, suggesting an additional mechanism of glucocorticoid action is present in neural cells. Our results thus show that ARGLU1 is a novel factor for embryonic development that modulates basal transcription and alternative splicing in neural cells with consequences for glucocorticoid signaling.
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Affiliation(s)
- Lilia Magomedova
- Department of Pharmaceutical Sciences, University of Toronto, Toronto, ON M5S 3M2, Canada
| | - Jens Tiefenbach
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Emma Zilberman
- Department of Pharmaceutical Sciences, University of Toronto, Toronto, ON M5S 3M2, Canada
| | - Florian Le Billan
- Department of Pharmaceutical Sciences, University of Toronto, Toronto, ON M5S 3M2, Canada
| | - Veronique Voisin
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Michael Saikali
- Department of Pharmaceutical Sciences, University of Toronto, Toronto, ON M5S 3M2, Canada
| | - Vincent Boivin
- Département de biochimie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, QC J1E 4K8, Canada
| | - Melanie Robitaille
- Department of Pharmaceutical Sciences, University of Toronto, Toronto, ON M5S 3M2, Canada
| | - Serge Gueroussov
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Manuel Irimia
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Debashish Ray
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Rucha Patel
- Department of Pharmaceutical Sciences, University of Toronto, Toronto, ON M5S 3M2, Canada
| | - ChangJiang Xu
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Pancharatnam Jeyasuria
- Department of Obstetrics and Gynecology, Wayne State University Perinatal Initiative, School of Medicine, Wayne State University, Detroit, MI, USA
| | - Gary D Bader
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Timothy R Hughes
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Quaid D Morris
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Michelle S Scott
- Département de biochimie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, QC J1E 4K8, Canada
| | - Henry Krause
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Stephane Angers
- Department of Pharmaceutical Sciences, University of Toronto, Toronto, ON M5S 3M2, Canada.,Department of Biochemistry,University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Benjamin J Blencowe
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Carolyn L Cummins
- Department of Pharmaceutical Sciences, University of Toronto, Toronto, ON M5S 3M2, Canada
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13
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Amirkhah R, Naderi-Meshkin H, Shah JS, Dunne PD, Schmitz U. The Intricate Interplay between Epigenetic Events, Alternative Splicing and Noncoding RNA Deregulation in Colorectal Cancer. Cells 2019; 8:cells8080929. [PMID: 31430887 PMCID: PMC6721676 DOI: 10.3390/cells8080929] [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: 07/31/2019] [Revised: 08/16/2019] [Accepted: 08/16/2019] [Indexed: 12/17/2022] Open
Abstract
Colorectal cancer (CRC) results from a transformation of colonic epithelial cells into adenocarcinoma cells due to genetic and epigenetic instabilities, alongside remodelling of the surrounding stromal tumour microenvironment. Epithelial-specific epigenetic variations escorting this process include chromatin remodelling, histone modifications and aberrant DNA methylation, which influence gene expression, alternative splicing and function of non-coding RNA. In this review, we first highlight epigenetic modulators, modifiers and mediators in CRC, then we elaborate on causes and consequences of epigenetic alterations in CRC pathogenesis alongside an appraisal of the complex feedback mechanisms realized through alternative splicing and non-coding RNA regulation. An emphasis in our review is put on how this intricate network of epigenetic and post-transcriptional gene regulation evolves during the initiation, progression and metastasis formation in CRC.
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Affiliation(s)
- Raheleh Amirkhah
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, Belfast BT9 7AE, UK
- Nastaran Center for Cancer Prevention (NCCP), Mashhad 9185765476, Iran
| | - Hojjat Naderi-Meshkin
- Nastaran Center for Cancer Prevention (NCCP), Mashhad 9185765476, Iran
- Stem Cells and Regenerative Medicine Research Group, Academic Center for Education, Culture Research (ACECR), Khorasan Razavi Branch, Mashhad 9177949367, Iran
| | - Jaynish S Shah
- Gene & Stem Cell Therapy Program Centenary Institute, The University of Sydney, Camperdown, NSW 2050, Australia
- Sydney Medical School, The University of Sydney, Camperdown, NSW 2050, Australia
| | - Philip D Dunne
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, Belfast BT9 7AE, UK
| | - Ulf Schmitz
- Gene & Stem Cell Therapy Program Centenary Institute, The University of Sydney, Camperdown, NSW 2050, Australia.
- Sydney Medical School, The University of Sydney, Camperdown, NSW 2050, Australia.
- Computational BioMedicine Laboratory Centenary Institute, The University of Sydney, Camperdown, NSW 2050, Australia.
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14
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Sharma P, Lioutas A, Fernandez-Fuentes N, Quilez J, Carbonell-Caballero J, Wright RHG, Di Vona C, Le Dily F, Schüller R, Eick D, Oliva B, Beato M. Arginine Citrullination at the C-Terminal Domain Controls RNA Polymerase II Transcription. Mol Cell 2018; 73:84-96.e7. [PMID: 30472187 DOI: 10.1016/j.molcel.2018.10.016] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Revised: 08/31/2018] [Accepted: 10/09/2018] [Indexed: 12/21/2022]
Abstract
The post-translational modification of key residues at the C-terminal domain of RNA polymerase II (RNAP2-CTD) coordinates transcription, splicing, and RNA processing by modulating its capacity to act as a landing platform for a variety of protein complexes. Here, we identify a new modification at the CTD, the deimination of arginine and its conversion to citrulline by peptidyl arginine deiminase 2 (PADI2), an enzyme that has been associated with several diseases, including cancer. We show that, among PADI family members, only PADI2 citrullinates R1810 (Cit1810) at repeat 31 of the CTD. Depletion of PADI2 or loss of R1810 results in accumulation of RNAP2 at transcription start sites, reduced gene expression, and inhibition of cell proliferation. Cit1810 is needed for interaction with the P-TEFb (positive transcription elongation factor b) kinase complex and for its recruitment to chromatin. In this way, CTD-Cit1810 favors RNAP2 pause release and efficient transcription in breast cancer cells.
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Affiliation(s)
- Priyanka Sharma
- Gene Regulation, Stem Cells and Cancer Program, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology (BIST), Barcelona 08003, Spain
| | - Antonios Lioutas
- Gene Regulation, Stem Cells and Cancer Program, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology (BIST), Barcelona 08003, Spain
| | - Narcis Fernandez-Fuentes
- IBERS, Institute of Biological, Environmental and Rural Science, Aberystwyth University, Aberystwyth SY23 3EB, UK
| | - Javier Quilez
- Gene Regulation, Stem Cells and Cancer Program, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology (BIST), Barcelona 08003, Spain
| | - José Carbonell-Caballero
- Gene Regulation, Stem Cells and Cancer Program, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology (BIST), Barcelona 08003, Spain
| | - Roni H G Wright
- Gene Regulation, Stem Cells and Cancer Program, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology (BIST), Barcelona 08003, Spain
| | - Chiara Di Vona
- Gene Regulation, Stem Cells and Cancer Program, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology (BIST), Barcelona 08003, Spain
| | - François Le Dily
- Gene Regulation, Stem Cells and Cancer Program, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology (BIST), Barcelona 08003, Spain
| | - Roland Schüller
- Department of Molecular Epigenetics, Helmholtz Center Munich, Center of Integrated Protein Science, Munich, Germany
| | - Dirk Eick
- Department of Molecular Epigenetics, Helmholtz Center Munich, Center of Integrated Protein Science, Munich, Germany
| | - Baldomero Oliva
- Universitat Pompeu Fabra (UPF), Barcelona, Spain; Structural Bioinformatics Laboratory (GRIB-IMIM), Department of Experimental and Health Sciences, Barcelona 08003, Spain
| | - Miguel Beato
- Gene Regulation, Stem Cells and Cancer Program, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology (BIST), Barcelona 08003, Spain; Universitat Pompeu Fabra (UPF), Barcelona, Spain.
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15
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A saga of cancer epigenetics: linking epigenetics to alternative splicing. Biochem J 2017; 474:885-896. [PMID: 28270561 DOI: 10.1042/bcj20161047] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 12/29/2016] [Accepted: 01/05/2017] [Indexed: 12/14/2022]
Abstract
The discovery of an increasing number of alternative splicing events in the human genome highlighted that ∼94% of genes generate alternatively spliced transcripts that may produce different protein isoforms with diverse functions. It is now well known that several diseases are a direct and indirect consequence of aberrant splicing events in humans. In addition to the conventional mode of alternative splicing regulation by 'cis' RNA-binding sites and 'trans' RNA-binding proteins, recent literature provides enormous evidence for epigenetic regulation of alternative splicing. The epigenetic modifications may regulate alternative splicing by either influencing the transcription elongation rate of RNA polymerase II or by recruiting a specific splicing regulator via different chromatin adaptors. The epigenetic alterations and aberrant alternative splicing are known to be associated with various diseases individually, but this review discusses/highlights the latest literature on the role of epigenetic alterations in the regulation of alternative splicing and thereby cancer progression. This review also points out the need for further studies to understand the interplay between epigenetic modifications and aberrant alternative splicing in cancer progression.
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16
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Hollander D, Naftelberg S, Lev-Maor G, Kornblihtt AR, Ast G. How Are Short Exons Flanked by Long Introns Defined and Committed to Splicing? Trends Genet 2016; 32:596-606. [PMID: 27507607 DOI: 10.1016/j.tig.2016.07.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2016] [Revised: 07/19/2016] [Accepted: 07/22/2016] [Indexed: 11/19/2022]
Abstract
The splice sites (SSs) delimiting an intron are brought together in the earliest step of spliceosome assembly yet it remains obscure how SS pairing occurs, especially when introns are thousands of nucleotides long. Splicing occurs in vivo in mammals within minutes regardless of intron length, implying that SS pairing can instantly follow transcription. Also, factors required for SS pairing, such as the U1 small nuclear ribonucleoprotein (snRNP) and U2AF65, associate with RNA polymerase II (RNAPII), while nucleosomes preferentially bind exonic sequences and associate with U2 snRNP. Based on recent publications, we assume that the 5' SS-bound U1 snRNP can remain tethered to RNAPII until complete synthesis of the downstream intron and exon. An additional U1 snRNP then binds the downstream 5' SS, whereas the RNAPII-associated U2AF65 binds the upstream 3' SS to facilitate SS pairing along with exon definition. Next, the nucleosome-associated U2 snRNP binds the branch site to advance splicing complex assembly. This may explain how RNAPII and chromatin are involved in spliceosome assembly and how introns lengthened during evolution with a relatively minimal compromise in splicing.
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Affiliation(s)
- Dror Hollander
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv 69978, Israel
| | - Shiran Naftelberg
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv 69978, Israel
| | - Galit Lev-Maor
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv 69978, Israel
| | - Alberto R Kornblihtt
- IFIBYNE-UBA-CONICET and Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón II, C1428EHA Buenos Aires, Argentina
| | - Gil Ast
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv 69978, Israel.
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17
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Interconnections Between RNA-Processing Pathways Revealed by a Sequencing-Based Genetic Screen for Pre-mRNA Splicing Mutants in Fission Yeast. G3-GENES GENOMES GENETICS 2016; 6:1513-23. [PMID: 27172183 PMCID: PMC4889648 DOI: 10.1534/g3.116.027508] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Pre-mRNA splicing is an essential component of eukaryotic gene expression and is highly conserved from unicellular yeasts to humans. Here, we present the development and implementation of a sequencing-based reverse genetic screen designed to identify nonessential genes that impact pre-mRNA splicing in the fission yeast Schizosaccharomyces pombe, an organism that shares many of the complex features of splicing in higher eukaryotes. Using a custom-designed barcoding scheme, we simultaneously queried ∼3000 mutant strains for their impact on the splicing efficiency of two endogenous pre-mRNAs. A total of 61 nonessential genes were identified whose deletions resulted in defects in pre-mRNA splicing; enriched among these were factors encoding known or predicted components of the spliceosome. Included among the candidates identified here are genes with well-characterized roles in other RNA-processing pathways, including heterochromatic silencing and 3ʹ end processing. Splicing-sensitive microarrays confirm broad splicing defects for many of these factors, revealing novel functional connections between these pathways.
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18
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Jimeno-González S, Reyes JC. Chromatin structure and pre-mRNA processing work together. Transcription 2016; 7:63-8. [PMID: 27028548 PMCID: PMC4984687 DOI: 10.1080/21541264.2016.1168507] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Revised: 03/14/2016] [Accepted: 03/14/2016] [Indexed: 10/22/2022] Open
Abstract
Chromatin is the natural context for transcription elongation. However, the elongating RNA polymerase II (RNAPII) is forced to pause by the positioned nucleosomes present in gene bodies. Here, we briefly discuss the current results suggesting that those pauses could serve as a mechanism to coordinate transcription elongation with pre-mRNA processing. Further, histone post-translational modifications have been found to regulate the recruitment of factors involved in pre-mRNA processing. This view highlights the important regulatory role of the chromatin context in the whole process of the mature mRNA synthesis.
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Affiliation(s)
- Silvia Jimeno-González
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Consejo Superior de Investigaciones Científicas (CSIC), Seville, Spain
| | - José C. Reyes
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Consejo Superior de Investigaciones Científicas (CSIC), Seville, Spain
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19
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Saldi T, Cortazar MA, Sheridan RM, Bentley DL. Coupling of RNA Polymerase II Transcription Elongation with Pre-mRNA Splicing. J Mol Biol 2016; 428:2623-2635. [PMID: 27107644 DOI: 10.1016/j.jmb.2016.04.017] [Citation(s) in RCA: 175] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Revised: 03/27/2016] [Accepted: 04/12/2016] [Indexed: 01/07/2023]
Abstract
Pre-mRNA maturation frequently occurs at the same time and place as transcription by RNA polymerase II. The co-transcriptionality of mRNA processing has permitted the evolution of mechanisms that functionally couple transcription elongation with diverse events that occur on the nascent RNA. This review summarizes the current understanding of the relationship between transcriptional elongation through a chromatin template and co-transcriptional splicing including alternative splicing decisions that affect the expression of most human genes.
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Affiliation(s)
- Tassa Saldi
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, P.O. Box 6511, Aurora, CO 80045, USA
| | - Michael A Cortazar
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, P.O. Box 6511, Aurora, CO 80045, USA
| | - Ryan M Sheridan
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, P.O. Box 6511, Aurora, CO 80045, USA
| | - David L Bentley
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, P.O. Box 6511, Aurora, CO 80045, USA.
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20
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Liu G, Xing Y, Zhao H, Wang J, Shang Y, Cai L. A deformation energy-based model for predicting nucleosome dyads and occupancy. Sci Rep 2016; 6:24133. [PMID: 27053067 PMCID: PMC4823781 DOI: 10.1038/srep24133] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 03/21/2016] [Indexed: 12/14/2022] Open
Abstract
Nucleosome plays an essential role in various cellular processes, such as DNA replication, recombination, and transcription. Hence, it is important to decode the mechanism of nucleosome positioning and identify nucleosome positions in the genome. In this paper, we present a model for predicting nucleosome positioning based on DNA deformation, in which both bending and shearing of the nucleosomal DNA are considered. The model successfully predicted the dyad positions of nucleosomes assembled in vitro and the in vitro map of nucleosomes in Saccharomyces cerevisiae. Applying the model to Caenorhabditis elegans and Drosophila melanogaster, we achieved satisfactory results. Our data also show that shearing energy of nucleosomal DNA outperforms bending energy in nucleosome occupancy prediction and the ability to predict nucleosome dyad positions is attributed to bending energy that is associated with rotational positioning of nucleosomes.
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Affiliation(s)
- Guoqing Liu
- The Institute of Bioengineering and Technology, Inner Mongolia University of Science and Technology, Baotou, 014010, China.,Computational Systems Biology Lab, Department of Biochemistry and Molecular Biology, Institute of Bioinformatics, University of Georgia, Athens, GA 30602, USA
| | - Yongqiang Xing
- The Institute of Bioengineering and Technology, Inner Mongolia University of Science and Technology, Baotou, 014010, China
| | - Hongyu Zhao
- The Institute of Bioengineering and Technology, Inner Mongolia University of Science and Technology, Baotou, 014010, China
| | - Jianying Wang
- The Institute of Bioengineering and Technology, Inner Mongolia University of Science and Technology, Baotou, 014010, China.,State Key Laboratory for Utilization of Bayan Obo Multi-Metallic Resources, Inner Mongolia University of Science and Technology, Baotou, 014010, China
| | - Yu Shang
- Computational Systems Biology Lab, Department of Biochemistry and Molecular Biology, Institute of Bioinformatics, University of Georgia, Athens, GA 30602, USA.,College of Computer Science and Technology, Jilin University, Changchun, Jilin 130021, China
| | - Lu Cai
- The Institute of Bioengineering and Technology, Inner Mongolia University of Science and Technology, Baotou, 014010, China
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21
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Defective histone supply causes changes in RNA polymerase II elongation rate and cotranscriptional pre-mRNA splicing. Proc Natl Acad Sci U S A 2015; 112:14840-5. [PMID: 26578803 DOI: 10.1073/pnas.1506760112] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
RNA polymerase II (RNAPII) transcription elongation is a highly regulated process that greatly influences mRNA levels as well as pre-mRNA splicing. Despite many studies in vitro, how chromatin modulates RNAPII elongation in vivo is still unclear. Here, we show that a decrease in the level of available canonical histones leads to more accessible chromatin with decreased levels of canonical histones and variants H2A.X and H2A.Z and increased levels of H3.3. With this altered chromatin structure, the RNAPII elongation rate increases, and the kinetics of pre-mRNA splicing is delayed with respect to RNAPII elongation. Consistent with the kinetic model of cotranscriptional splicing, the rapid RNAPII elongation induced by histone depletion promotes the skipping of variable exons in the CD44 gene. Indeed, a slowly elongating mutant of RNAPII was able to rescue this defect, indicating that the defective splicing induced by histone depletion is a direct consequence of the increased elongation rate. In addition, genome-wide analysis evidenced that histone reduction promotes widespread alterations in pre-mRNA processing, including intron retention and changes in alternative splicing. Our data demonstrate that pre-mRNA splicing may be regulated by chromatin structure through the modulation of the RNAPII elongation rate.
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22
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Curado J, Iannone C, Tilgner H, Valcárcel J, Guigó R. Promoter-like epigenetic signatures in exons displaying cell type-specific splicing. Genome Biol 2015; 16:236. [PMID: 26498677 PMCID: PMC4619081 DOI: 10.1186/s13059-015-0797-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2015] [Accepted: 10/05/2015] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND Pre-mRNA splicing occurs mainly co-transcriptionally, and both nucleosome density and histone modifications have been proposed to play a role in splice site recognition and regulation. However, the extent and mechanisms behind this interplay remain poorly understood. RESULTS We use transcriptomic and epigenomic data generated by the ENCODE project to investigate the association between chromatin structure and alternative splicing. We find a strong and significant positive association between H3K9ac, H3K27ac, H3K4me3, epigenetic marks characteristic of active promoters, and exon inclusion in a small but well-defined class of exons, representing approximately 4 % of all regulated exons. These exons are systematically maintained at comparatively low levels of inclusion across cell types, but their inclusion is significantly enhanced in particular cell types when in physical proximity to active promoters. CONCLUSION Histone modifications and other chromatin features that activate transcription can be co-opted to participate in the regulation of the splicing of exons that are in physical proximity to promoter regions.
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Affiliation(s)
- Joao Curado
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader, 88, 08003, Barcelona, Catalonia, Spain
- Graduate program in Areas of Basic and Applied Biology, Abel Salazar Biomedical Sciences Institute, University of Porto, 4099-003, Porto, Portugal
| | - Camilla Iannone
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader, 88, 08003, Barcelona, Catalonia, Spain
- Universitat Pompeu Fabra, Dr. Aiguader, 88, 08003, Barcelona, Catalonia, Spain
| | - Hagen Tilgner
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader, 88, 08003, Barcelona, Catalonia, Spain
- Department of Genetics, Stanford University, 300 Pasteur Dr., Stanford, CA, 94305-5120, USA
| | - Juan Valcárcel
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader, 88, 08003, Barcelona, Catalonia, Spain
- Universitat Pompeu Fabra, Dr. Aiguader, 88, 08003, Barcelona, Catalonia, Spain
- Institució Catalana de Recerca i Estudis Avançats, Pg Lluis Companys 23, 08010, Barcelona, Catalonia, Spain
| | - Roderic Guigó
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader, 88, 08003, Barcelona, Catalonia, Spain.
- Universitat Pompeu Fabra, Dr. Aiguader, 88, 08003, Barcelona, Catalonia, Spain.
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Warns JA, Davie JR, Dhasarathy A. Connecting the dots: chromatin and alternative splicing in EMT. Biochem Cell Biol 2015; 94:12-25. [PMID: 26291837 DOI: 10.1139/bcb-2015-0053] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Nature has devised sophisticated cellular machinery to process mRNA transcripts produced by RNA Polymerase II, removing intronic regions and connecting exons together, to produce mature RNAs. This process, known as splicing, is very closely linked to transcription. Alternative splicing, or the ability to produce different combinations of exons that are spliced together from the same genomic template, is a fundamental means of regulating protein complexity. Similar to transcription, both constitutive and alternative splicing can be regulated by chromatin and its associated factors in response to various signal transduction pathways activated by external stimuli. This regulation can vary between different cell types, and interference with these pathways can lead to changes in splicing, often resulting in aberrant cellular states and disease. The epithelial to mesenchymal transition (EMT), which leads to cancer metastasis, is influenced by alternative splicing events of chromatin remodelers and epigenetic factors such as DNA methylation and non-coding RNAs. In this review, we will discuss the role of epigenetic factors including chromatin, chromatin remodelers, DNA methyltransferases, and microRNAs in the context of alternative splicing, and discuss their potential involvement in alternative splicing during the EMT process.
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Affiliation(s)
- Jessica A Warns
- a Department of Basic Sciences, University of North Dakota School of Medicine and Health Sciences, 501 N. Columbia Road Stop 9061, Grand Forks, ND 58202-9061, USA
| | - James R Davie
- b Children's Hospital Research Institute of Manitoba, John Buhler Research Centre, Winnipeg, Manitoba R3E 3P4, Canada
| | - Archana Dhasarathy
- a Department of Basic Sciences, University of North Dakota School of Medicine and Health Sciences, 501 N. Columbia Road Stop 9061, Grand Forks, ND 58202-9061, USA
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Tejedor JR, Tilgner H, Iannone C, Guigó R, Valcárcel J. Role of six single nucleotide polymorphisms, risk factors in coronary disease, in OLR1 alternative splicing. RNA (NEW YORK, N.Y.) 2015; 21:1187-1202. [PMID: 25904137 PMCID: PMC4436670 DOI: 10.1261/rna.049890.115] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Accepted: 03/12/2015] [Indexed: 06/04/2023]
Abstract
The OLR1 gene encodes the oxidized low-density lipoprotein receptor (LOX-1), which is responsible for the cellular uptake of oxidized LDL (Ox-LDL), foam cell formation in atheroma plaques and atherosclerotic plaque rupture. Alternative splicing (AS) of OLR1 exon 5 generates two protein isoforms with antagonistic functions in Ox-LDL uptake. Previous work identified six single nucleotide polymorphisms (SNPs) in linkage disequilibrium that influence the inclusion levels of OLR1 exon 5 and correlate with the risk of cardiovascular disease. Here we use minigenes to recapitulate the effects of two allelic series (Low- and High-Risk) on OLR1 AS and identify one SNP in intron 4 (rs3736234) as the main contributor to the differences in exon 5 inclusion, while the other SNPs in the allelic series attenuate the drastic effects of this key SNP. Bioinformatic, proteomic, mutational and functional high-throughput analyses allowed us to define regulatory sequence motifs and identify SR protein family members (SRSF1, SRSF2) and HMGA1 as factors involved in the regulation of OLR1 AS. Our results suggest that antagonism between SRSF1 and SRSF2/HMGA1, and differential recognition of their regulatory motifs depending on the identity of the rs3736234 polymorphism, influence OLR1 exon 5 inclusion and the efficiency of Ox-LDL uptake, with potential implications for atherosclerosis and coronary disease.
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Affiliation(s)
- J Ramón Tejedor
- Centre de Regulació Genòmica, 08003 Barcelona, Spain Universitat Pompeu Fabra, 08003 Barcelona, Spain
| | - Hagen Tilgner
- Centre de Regulació Genòmica, 08003 Barcelona, Spain Universitat Pompeu Fabra, 08003 Barcelona, Spain
| | - Camilla Iannone
- Centre de Regulació Genòmica, 08003 Barcelona, Spain Universitat Pompeu Fabra, 08003 Barcelona, Spain
| | - Roderic Guigó
- Centre de Regulació Genòmica, 08003 Barcelona, Spain Universitat Pompeu Fabra, 08003 Barcelona, Spain
| | - Juan Valcárcel
- Centre de Regulació Genòmica, 08003 Barcelona, Spain Universitat Pompeu Fabra, 08003 Barcelona, Spain Institució Catalana de Recerca i Estudis Avançats, 08020 Barcelona, Spain
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