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Riccardi F, Romano G, Licastro D, Pagani F. Age-dependent regulation of ELP1 exon 20 splicing in Familial Dysautonomia by RNA Polymerase II kinetics and chromatin structure. PLoS One 2024; 19:e0298965. [PMID: 38829854 PMCID: PMC11146744 DOI: 10.1371/journal.pone.0298965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2023] [Accepted: 02/01/2024] [Indexed: 06/05/2024] Open
Abstract
Familial Dysautonomia (FD) is a rare disease caused by ELP1 exon 20 skipping. Here we clarify the role of RNA Polymerase II (RNAPII) and chromatin on this splicing event. A slow RNAPII mutant and chromatin-modifying chemicals that reduce the rate of RNAPII elongation induce exon skipping whereas chemicals that create a more relaxed chromatin exon inclusion. In the brain of a mouse transgenic for the human FD-ELP1 we observed on this gene an age-dependent decrease in the RNAPII density profile that was most pronounced on the alternative exon, a robust increase in the repressive marks H3K27me3 and H3K9me3 and a decrease of H3K27Ac, together with a progressive reduction in ELP1 exon 20 inclusion level. In HEK 293T cells, selective drug-induced demethylation of H3K27 increased RNAPII elongation on ELP1 and SMN2, promoted the inclusion of the corresponding alternative exons, and, by RNA-sequencing analysis, induced changes in several alternative splicing events. These data suggest a co-transcriptional model of splicing regulation in which age-dependent changes in H3K27me3/Ac modify the rate of RNAPII elongation and affect processing of ELP1 alternative exon 20.
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Affiliation(s)
- Federico Riccardi
- Human Molecular Genetics, International Centre for Genetic Engineering and Biotechnology, Padriciano, Trieste, Italy
| | - Giulia Romano
- Human Molecular Genetics, International Centre for Genetic Engineering and Biotechnology, Padriciano, Trieste, Italy
| | - Danilo Licastro
- Laboratorio di Genomica ed Epigenomica, AREA Science Park, Padriciano, Trieste, Italy
| | - Franco Pagani
- Human Molecular Genetics, International Centre for Genetic Engineering and Biotechnology, Padriciano, Trieste, Italy
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2
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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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3
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Alternative splicing diversifies the skeletal muscle transcriptome during prolonged spaceflight. Skelet Muscle 2022; 12:11. [PMID: 35642060 PMCID: PMC9153194 DOI: 10.1186/s13395-022-00294-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 04/05/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND As the interest in manned spaceflight increases, so does the requirement to understand the transcriptomic mechanisms that underlay the detrimental physiological adaptations of skeletal muscle to microgravity. While microgravity-induced differential gene expression (DGE) has been extensively investigated, the contribution of differential alternative splicing (DAS) to the plasticity and functional status of the skeletal muscle transcriptome has not been studied in an animal model. Therefore, by evaluating both DGE and DAS across spaceflight, we set out to provide the first comprehensive characterization of the transcriptomic landscape of skeletal muscle during exposure to microgravity. METHODS RNA-sequencing, immunohistochemistry, and morphological analyses were conducted utilizing total RNA and tissue sections isolated from the gastrocnemius and quadriceps muscles of 30-week-old female BALB/c mice exposed to microgravity or ground control conditions for 9 weeks. RESULTS In response to microgravity, the skeletal muscle transcriptome was remodeled via both DGE and DAS. Importantly, while DGE showed variable gene network enrichment, DAS was enriched in structural and functional gene networks of skeletal muscle, resulting in the expression of alternatively spliced transcript isoforms that have been associated with the physiological changes to skeletal muscle in microgravity, including muscle atrophy and altered fiber type function. Finally, RNA-binding proteins, which are required for regulation of pre-mRNA splicing, were themselves differentially spliced but not differentially expressed, an upstream event that is speculated to account for the downstream splicing changes identified in target skeletal muscle genes. CONCLUSIONS Our work serves as the first investigation of coordinate changes in DGE and DAS in large limb muscles across spaceflight. It opens up a new opportunity to understand (i) the molecular mechanisms by which splice variants of skeletal muscle genes regulate the physiological adaptations of skeletal muscle to microgravity and (ii) how small molecule splicing regulator therapies might thwart muscle atrophy and alterations to fiber type function during prolonged spaceflight.
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4
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Kitamura K, Nimura K. Regulation of RNA Splicing: Aberrant Splicing Regulation and Therapeutic Targets in Cancer. Cells 2021; 10:923. [PMID: 33923658 PMCID: PMC8073995 DOI: 10.3390/cells10040923] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Revised: 03/16/2021] [Accepted: 04/14/2021] [Indexed: 02/06/2023] Open
Abstract
RNA splicing is a critical step in the maturation of precursor mRNA (pre-mRNA) by removing introns and exons. The combination of inclusion and exclusion of introns and exons in pre-mRNA can generate vast diversity in mature mRNA from a limited number of genes. Cancer cells acquire cancer-specific mechanisms through aberrant splicing regulation to acquire resistance to treatment and to promote malignancy. Splicing regulation involves many factors, such as proteins, non-coding RNAs, and DNA sequences at many steps. Thus, the dysregulation of splicing is caused by many factors, including mutations in RNA splicing factors, aberrant expression levels of RNA splicing factors, small nuclear ribonucleoproteins biogenesis, mutations in snRNA, or genomic sequences that are involved in the regulation of splicing, such as 5' and 3' splice sites, branch point site, splicing enhancer/silencer, and changes in the chromatin status that affect the splicing profile. This review focuses on the dysregulation of RNA splicing related to cancer and the associated therapeutic methods.
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Affiliation(s)
- Koji Kitamura
- Division of Gene Therapy Science, Department of Genome Biology, Graduate School of Medicine, Osaka University, 2-2 Yamada-oka, Suita, Osaka 565-0871, Japan;
- Department of Otorhinolaryngology-Head and Neck Surgery, Graduate School of Medicine, Osaka University, 2-2 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Keisuke Nimura
- Division of Gene Therapy Science, Department of Genome Biology, Graduate School of Medicine, Osaka University, 2-2 Yamada-oka, Suita, Osaka 565-0871, Japan;
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5
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Caizzi L, Monteiro-Martins S, Schwalb B, Lysakovskaia K, Schmitzova J, Sawicka A, Chen Y, Lidschreiber M, Cramer P. Efficient RNA polymerase II pause release requires U2 snRNP function. Mol Cell 2021; 81:1920-1934.e9. [PMID: 33689748 DOI: 10.1016/j.molcel.2021.02.016] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 01/07/2021] [Accepted: 02/10/2021] [Indexed: 12/21/2022]
Abstract
Transcription by RNA polymerase II (Pol II) is coupled to pre-mRNA splicing, but the underlying mechanisms remain poorly understood. Co-transcriptional splicing requires assembly of a functional spliceosome on nascent pre-mRNA, but whether and how this influences Pol II transcription remains unclear. Here we show that inhibition of pre-mRNA branch site recognition by the spliceosome component U2 snRNP leads to a widespread and strong decrease in new RNA synthesis from human genes. Multiomics analysis reveals that inhibition of U2 snRNP function increases the duration of Pol II pausing in the promoter-proximal region, impairs recruitment of the pause release factor P-TEFb, and reduces Pol II elongation velocity at the beginning of genes. Our results indicate that efficient release of paused Pol II into active transcription elongation requires the formation of functional spliceosomes and that eukaryotic mRNA biogenesis relies on positive feedback from the splicing machinery to the transcription machinery.
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Affiliation(s)
- Livia Caizzi
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Sara Monteiro-Martins
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Björn Schwalb
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Kseniia Lysakovskaia
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Jana Schmitzova
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Anna Sawicka
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Ying Chen
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Michael Lidschreiber
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Patrick Cramer
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany.
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6
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Role of promoters in regulating alternative splicing. Gene 2021; 782:145523. [PMID: 33667606 DOI: 10.1016/j.gene.2021.145523] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Revised: 12/31/2020] [Accepted: 02/09/2021] [Indexed: 01/19/2023]
Abstract
Alternative splicing (AS) plays a critical role in enhancing proteome complexity in higher eukaryotes. Almost all the multi intron-containing genes undergo AS in humans. Splicing mainly occurs co-transcriptionally, where RNA polymerase II (RNA pol II) plays a crucial role in coordinating transcription and pre-mRNA splicing. Aberrant AS leads to non-functional proteins causative in various pathophysiological conditions such as cancers, neurodegenerative diseases, and muscular dystrophies. Transcription and pre-mRNA splicing are deeply interconnected and can influence each other's functions. Several studies evinced that specific promoters employed by RNA pol II dictate the RNA processing decisions. Promoter-specific recruitment of certain transcriptional factors or transcriptional coactivators influences splicing, and the extent to which these factors affect splicing has not been discussed in detail. Here, in this review, various DNA-binding proteins and their influence on promoter-specific AS are extensively discussed. Besides, this review highlights how the promoter-specific epigenetic changes might regulate AS.
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7
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Linking transcription, RNA polymerase II elongation and alternative splicing. Biochem J 2020; 477:3091-3104. [DOI: 10.1042/bcj20200475] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 07/31/2020] [Accepted: 08/04/2020] [Indexed: 12/21/2022]
Abstract
Gene expression is an intricately regulated process that is at the basis of cell differentiation, the maintenance of cell identity and the cellular responses to environmental changes. Alternative splicing, the process by which multiple functionally distinct transcripts are generated from a single gene, is one of the main mechanisms that contribute to expand the coding capacity of genomes and help explain the level of complexity achieved by higher organisms. Eukaryotic transcription is subject to multiple layers of regulation both intrinsic — such as promoter structure — and dynamic, allowing the cell to respond to internal and external signals. Similarly, alternative splicing choices are affected by all of these aspects, mainly through the regulation of transcription elongation, making it a regulatory knob on a par with the regulation of gene expression levels. This review aims to recapitulate some of the history and stepping-stones that led to the paradigms held today about transcription and splicing regulation, with major focus on transcription elongation and its effect on alternative splicing.
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8
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Botto AEC, Muñoz JC, Giono LE, Nieto-Moreno N, Cuenca C, Kornblihtt AR, Muñoz MJ. Reciprocal regulation between alternative splicing and the DNA damage response. Genet Mol Biol 2020; 43:e20190111. [PMID: 32236390 PMCID: PMC7197977 DOI: 10.1590/1678-4685-gmb-2019-0111] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 12/16/2019] [Indexed: 12/16/2022] Open
Abstract
Splicing, the process that catalyzes intron removal and flanking exon ligation, can occur in different ways (alternative splicing) in immature RNAs transcribed from a single gene. In order to adapt to a particular context, cells modulate not only the quantity but also the quality (alternative isoforms) of their transcriptome. Since 95% of the human coding genome is subjected to alternative splicing regulation, it is expected that many cellular pathways are modulated by alternative splicing, as is the case for the DNA damage response. Moreover, recent evidence demonstrates that upon a genotoxic insult, classical DNA damage response kinases such as ATM, ATR and DNA-PK orchestrate the gene expression response therefore modulating alternative splicing which, in a reciprocal way, shapes the response to a damaging agent.
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Affiliation(s)
- Adrian E Cambindo Botto
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Fisiologia, Biologia Molecular y Celular, Instituto de Fisiologia, Biologia Molecular y Neurociencias (IFIBYNE-UBA-CONICET), Buenos Aires, Argentina
| | - Juan C Muñoz
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Fisiologia, Biologia Molecular y Celular, Instituto de Fisiologia, Biologia Molecular y Neurociencias (IFIBYNE-UBA-CONICET), Buenos Aires, Argentina
| | - Luciana E Giono
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Fisiologia, Biologia Molecular y Celular, Instituto de Fisiologia, Biologia Molecular y Neurociencias (IFIBYNE-UBA-CONICET), Buenos Aires, Argentina
| | - Nicolás Nieto-Moreno
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Fisiologia, Biologia Molecular y Celular, Instituto de Fisiologia, Biologia Molecular y Neurociencias (IFIBYNE-UBA-CONICET), Buenos Aires, Argentina
| | - Carmen Cuenca
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Fisiologia, Biologia Molecular y Celular, Instituto de Fisiologia, Biologia Molecular y Neurociencias (IFIBYNE-UBA-CONICET), Buenos Aires, Argentina
| | - Alberto R Kornblihtt
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Fisiologia, Biologia Molecular y Celular, Instituto de Fisiologia, Biologia Molecular y Neurociencias (IFIBYNE-UBA-CONICET), Buenos Aires, Argentina
| | - Manuel J Muñoz
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Fisiologia, Biologia Molecular y Celular, Instituto de Fisiologia, Biologia Molecular y Neurociencias (IFIBYNE-UBA-CONICET), Buenos Aires, Argentina.,Fondazione Istituto FIRC di Oncologia Molecolare (IFOM), Milan, Italy.,Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Biodiversidad y Biología Experimental, Buenos Aires, Argentina
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9
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Cappabianca L, Guadagni S, Maccarone R, Sebastiano M, Chiominto A, Farina AR, Mackay AR. A pilot study of alternative TrkAIII splicing in Merkel cell carcinoma: a potential oncogenic mechanism and novel therapeutic target. J Exp Clin Cancer Res 2019; 38:424. [PMID: 31640749 PMCID: PMC6805356 DOI: 10.1186/s13046-019-1425-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Accepted: 09/16/2019] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND Merkel cell carcinomas (MCCs) are rare, aggressive, therapeutically-challenging skin tumours that are increasing in incidence and have poor survival rates. The majority are caused by genomic Merkel cell polyomavirus (MCPyV) integration and MCPyV T-antigen expression. Recently, a potential oncogenic role for the tropomyosin-related tyrosine kinase A receptor (TrkA) has been proposed in MCC. Alternative TrkAIII splicing is a TrkA oncogenic activation mechanism that can be promoted by SV40 large T-antigen, an analogue of MCPyV large T-antigen. In this pilot study, therefore, we have evaluated TrkAIII splicing as a novel potential oncogenic mechanism and therapeutic target in MCPyV positive MCC. METHODS Formalin-fixed paraffin-embedded MCC tissues, consisting of 10 stage IV, 1 stage IIIB, 1 stage IIB, 4 stage IIA and 2 stage I tumours, from patients diagnosed and treated from September 2006 to March, 2019, at the University of L'Aquila, L'Aquila, Italy, were compared to 3 primary basal cell carcinomas (BCCs), 3 primary squamous cell carcinomas (SCCs) and 2 normal skin samples by RT-PCR for MCPyV large T-antigen, small T-antigen, VP-1 expression and alternative TrkAIII splicing and by indirect IF for evidence of intracellular TrkA isoform expression and activation. RESULTS 9 of 10 Recurrent stage IV MCCs were from patients (P.1-3) treated with surgery plus loco-regional Melphalan chemotherapy and remaining MMCs, including 1 stage IV tumour, were from patients treated with surgery alone (P. 4-11). All MCPyV positive MCCs exhibiting MCPyV large T-antigen expression (17 of 18MCCs, 90%) exhibited alternative TrkAIII mRNA splicing (100%), which was exclusive in a significant number and predominant (> 50%) in all stage IV MCCs and the majority of stage 1-III MCCs. MCCs with higher TrkAIII to 18S rRNA expression ratios also exhibited strong or intermediate immunoreactivity to anti-TrkA antibodies, consistent with cytoplasmic TrkAIII expression and activation. In contrast, the MCPyV negative MCC, BCCs, SCCs and normal skin tissues all exhibited exclusive fully-spliced TrkA mRNA expression, associated with variable immunoreactivity for non-phosphorylated but not phosphorylated TrkA. CONCLUSIONS MCPyV positive MCCs but not MCPyV negative MCC, BCCs and SCCs exhibit predominant alternative TrkAIII splicing, with evidence of intracellular TrkAIII activation. This establishes a new potential MCC subset, unveils a novel potential MCPyV oncogenic mechanism and identifies TrkAIII as a novel potential therapeutic target in MCPyV positive MCC.
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Affiliation(s)
- Lucia Cappabianca
- Department of Applied Clinical and Biotechnological Sciences, University of L’Aquila, 67100 L’Aquila, Italy
| | - Stefano Guadagni
- Department of Applied Clinical and Biotechnological Sciences, University of L’Aquila, 67100 L’Aquila, Italy
| | - Rita Maccarone
- Department of Applied Clinical and Biotechnological Sciences, University of L’Aquila, 67100 L’Aquila, Italy
| | - Michela Sebastiano
- Department of Applied Clinical and Biotechnological Sciences, University of L’Aquila, 67100 L’Aquila, Italy
| | | | - Antonietta Rosella Farina
- Department of Applied Clinical and Biotechnological Sciences, University of L’Aquila, 67100 L’Aquila, Italy
| | - Andrew Reay Mackay
- Department of Applied Clinical and Biotechnological Sciences, University of L’Aquila, 67100 L’Aquila, Italy
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10
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Patop IL, Wüst S, Kadener S. Past, present, and future of circRNAs. EMBO J 2019; 38:e100836. [PMID: 31343080 PMCID: PMC6694216 DOI: 10.15252/embj.2018100836] [Citation(s) in RCA: 716] [Impact Index Per Article: 143.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 05/15/2019] [Accepted: 06/03/2019] [Indexed: 12/28/2022] Open
Abstract
Exonic circular RNAs (circRNAs) are covalently closed RNA molecules generated by a process named back-splicing. circRNAs are highly abundant in eukaryotes, and many of them are evolutionary conserved. In metazoans, circular RNAs are expressed in a tissue-specific manner, are highly stable, and accumulate with age in neural tissues. circRNA biogenesis can regulate the production of the linear RNA counterpart in cis as back-splicing competes with linear splicing. Recent reports also demonstrate functions for some circRNAs in trans: Certain circRNAs interact with microRNAs, some are translated, and circRNAs have been shown to regulate immune responses and behavior. Here, we review current knowledge about animal circRNAs and summarize new insights into potential circRNA functions, concepts of their origin, and possible future directions in the field.
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Affiliation(s)
| | - Stas Wüst
- Department of BiologyBrandeis UniversityWalthamMAUSA
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11
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Keiper S, Papasaikas P, Will CL, Valcárcel J, Girard C, Lührmann R. Smu1 and RED are required for activation of spliceosomal B complexes assembled on short introns. Nat Commun 2019; 10:3639. [PMID: 31409787 PMCID: PMC6692369 DOI: 10.1038/s41467-019-11293-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 07/01/2019] [Indexed: 12/02/2022] Open
Abstract
Human pre-catalytic spliceosomes contain several proteins that associate transiently just prior to spliceosome activation and are absent in yeast, suggesting that this critical step is more complex in higher eukaryotes. We demonstrate via RNAi coupled with RNA-Seq that two of these human-specific proteins, Smu1 and RED, function both as alternative splicing regulators and as general splicing factors and are required predominantly for efficient splicing of short introns. In vitro splicing assays reveal that Smu1 and RED promote spliceosome activation, and are essential for this step when the distance between the pre-mRNA’s 5′ splice site (SS) and branch site (BS) is sufficiently short. This Smu1-RED requirement can be bypassed when the 5′ and 3′ regions of short introns are physically separated. Our observations suggest that Smu1 and RED relieve physical constraints arising from a short 5′SS-BS distance, thereby enabling spliceosomes to overcome structural challenges associated with the splicing of short introns. Human spliceosome components Smu1 and RED regulate alternative splicing. Here the authors show that Smu1 and RED are also required for constitutive splicing of short introns.
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Affiliation(s)
- Sandra Keiper
- Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany
| | - Panagiotis Papasaikas
- Centre de Regulació Genòmica, The Barcelona Institute of Science and Technology and Universitat Pompeu Fabra, Dr. Aiguader 88, 08003, Barcelona, Spain.,Friedrich Miescher Institute for Biomedical Research (FMI), Maulbeerstrasse 66, 4058, Basel, Switzerland.,Swiss Institute of Bioinformatics, 4058, Basel, Switzerland
| | - Cindy L Will
- Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany
| | - Juan Valcárcel
- Centre de Regulació Genòmica, The Barcelona Institute of Science and Technology and Universitat Pompeu Fabra, Dr. Aiguader 88, 08003, Barcelona, Spain.,Institució Catalana de Recerca i Estudis Avançats (ICREA), Pg. Lluís Companys, 08010, Barcelona, Spain
| | - Cyrille Girard
- Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany.
| | - Reinhard Lührmann
- Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany.
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12
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Godoy Herz MA, Kornblihtt AR. Alternative Splicing and Transcription Elongation in Plants. FRONTIERS IN PLANT SCIENCE 2019; 10:309. [PMID: 30972082 PMCID: PMC6443983 DOI: 10.3389/fpls.2019.00309] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 02/26/2019] [Indexed: 05/19/2023]
Abstract
Alternative splicing and transcription elongation by RNA polymerase II (RNAPII) are two processes which are tightly connected. Splicing is a co-transcriptional process, and different experimental approaches show that splicing is coupled to transcription in Drosophila, yeast and mammals. However, little is known about coupling of transcription and alternative splicing in plants. The kinetic coupling explains how changes in RNAPII elongation rate influence alternative splicing choices. Recent work in Arabidopsis shows that expression of a dominant negative transcription elongation factor, TFIIS, enhances exon inclusion. Furthermore, the Arabidopsis transcription elongation complex has been recently described, providing new information about elongation factors that interact with elongating RNAPII. Light regulates alternative splicing in plants through a chloroplast retrograde signaling. We have recently shown that light promotes RNAPII elongation in the affected genes, while in darkness elongation is lower. These changes in transcription are consistent with elongation causing the observed changes in alternative splicing. Altogether, these findings provide evidence that coupling between transcription and alternative splicing is an important layer of gene expression regulation in plants.
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Affiliation(s)
- Micaela A. Godoy Herz
- Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (UBA), Buenos Aires, Argentina
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), CONICET-UBA, Buenos Aires, Argentina
| | - Alberto R. Kornblihtt
- Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (UBA), Buenos Aires, Argentina
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), CONICET-UBA, Buenos Aires, Argentina
- *Correspondence: Alberto R. Kornblihtt,
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Suess B, Kemmerer K, Weigand JE. Splicing and Alternative Splicing Impact on Gene Design. Synth Biol (Oxf) 2018. [DOI: 10.1002/9783527688104.ch7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- Beatrix Suess
- Department of Biology; Technische Universität Darmstadt; Schnittspahnstraße 10 64287 Darmstadt Germany
| | - Katrin Kemmerer
- Department of Biology; Technische Universität Darmstadt; Schnittspahnstraße 10 64287 Darmstadt Germany
| | - Julia E. Weigand
- Department of Biology; Technische Universität Darmstadt; Schnittspahnstraße 10 64287 Darmstadt Germany
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Transcription rate strongly affects splicing fidelity and cotranscriptionality in budding yeast. Genome Res 2017; 28:203-213. [PMID: 29254943 PMCID: PMC5793784 DOI: 10.1101/gr.225615.117] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 12/14/2017] [Indexed: 01/24/2023]
Abstract
The functional consequences of alternative splicing on altering the transcription rate have been the subject of intensive study in mammalian cells but less is known about effects of splicing on changing the transcription rate in yeast. We present several lines of evidence showing that slow RNA polymerase II elongation increases both cotranscriptional splicing and splicing efficiency and that faster elongation reduces cotranscriptional splicing and splicing efficiency in budding yeast, suggesting that splicing is more efficient when cotranscriptional. Moreover, we demonstrate that altering the RNA polymerase II elongation rate in either direction compromises splicing fidelity, and we reveal that splicing fidelity depends largely on intron length together with secondary structure and splice site score. These effects are notably stronger for the highly expressed ribosomal protein coding transcripts. We propose that transcription by RNA polymerase II is tuned to optimize the efficiency and accuracy of ribosomal protein gene expression, while allowing flexibility in splice site choice with the nonribosomal protein transcripts.
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15
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Rambout X, Dequiedt F, Maquat LE. Beyond Transcription: Roles of Transcription Factors in Pre-mRNA Splicing. Chem Rev 2017; 118:4339-4364. [PMID: 29251915 DOI: 10.1021/acs.chemrev.7b00470] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Whereas individual steps of protein-coding gene expression in eukaryotes can be studied in isolation in vitro, it has become clear that these steps are intimately connected within cells. Connections not only ensure quality control but also fine-tune the gene expression process, which must adapt to environmental changes while remaining robust. In this review, we systematically present proven and potential mechanisms by which sequence-specific DNA-binding transcription factors can alter gene expression beyond transcription initiation and regulate pre-mRNA splicing, and thereby mRNA isoform production, by (i) influencing transcription elongation rates, (ii) binding to pre-mRNA to recruit splicing factors, and/or (iii) blocking the association of splicing factors with pre-mRNA. We propose various mechanistic models throughout the review, in some cases without explicit supportive evidence, in hopes of providing fertile ground for future studies.
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16
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Fiszbein A, Giono LE, Quaglino A, Berardino BG, Sigaut L, von Bilderling C, Schor IE, Enriqué Steinberg JH, Rossi M, Pietrasanta LI, Caramelo JJ, Srebrow A, Kornblihtt AR. Alternative Splicing of G9a Regulates Neuronal Differentiation. Cell Rep 2016; 14:2797-808. [PMID: 26997278 DOI: 10.1016/j.celrep.2016.02.063] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Revised: 01/25/2016] [Accepted: 02/12/2016] [Indexed: 01/08/2023] Open
Abstract
Chromatin modifications are critical for the establishment and maintenance of differentiation programs. G9a, the enzyme responsible for histone H3 lysine 9 dimethylation in mammalian euchromatin, exists as two isoforms with differential inclusion of exon 10 (E10) through alternative splicing. We find that the G9a methyltransferase is required for differentiation of the mouse neuronal cell line N2a and that E10 inclusion increases during neuronal differentiation of cultured cells, as well as in the developing mouse brain. Although E10 inclusion greatly stimulates overall H3K9me2 levels, it does not affect G9a catalytic activity. Instead, E10 increases G9a nuclear localization. We show that the G9a E10(+) isoform is necessary for neuron differentiation and regulates the alternative splicing pattern of its own pre-mRNA, enhancing E10 inclusion. Overall, our findings indicate that by regulating its own alternative splicing, G9a promotes neuron differentiation and creates a positive feedback loop that reinforces cellular commitment to differentiation.
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Affiliation(s)
- Ana Fiszbein
- Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE-CONICET), Ciudad Universitaria Pabellón II, C1428EHA Buenos Aires, Argentina
| | - Luciana E Giono
- Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE-CONICET), Ciudad Universitaria Pabellón II, C1428EHA Buenos Aires, Argentina
| | - Ana Quaglino
- Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE-CONICET), Ciudad Universitaria Pabellón II, C1428EHA Buenos Aires, Argentina
| | - Bruno G Berardino
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria Pabellón II, C1428EHA Buenos Aires, Argentina
| | - Lorena Sigaut
- Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and IFIBA-CONICET, Cuidad Universitaria Pabellón I, C1428EHA Buenos Aires, Argentina
| | - Catalina von Bilderling
- Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and IFIBA-CONICET, Cuidad Universitaria Pabellón I, C1428EHA Buenos Aires, Argentina
| | - Ignacio E Schor
- Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE-CONICET), Ciudad Universitaria Pabellón II, C1428EHA Buenos Aires, Argentina
| | - Juliana H Enriqué Steinberg
- Instituto de Investigación en Biomedicina de Buenos Aires CONICET, Partner Institute of the Max Planck Society, C1425FQD Buenos Aires, Argentina
| | - Mario Rossi
- Instituto de Investigación en Biomedicina de Buenos Aires CONICET, Partner Institute of the Max Planck Society, C1425FQD Buenos Aires, Argentina
| | - Lía I Pietrasanta
- Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and IFIBA-CONICET, Cuidad Universitaria Pabellón I, C1428EHA Buenos Aires, Argentina; Centro de Microscopías Avanzadas, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Cuidad Universitaria, C1428EHA Buenos Aires, Argentina
| | - Julio J Caramelo
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria Pabellón II, C1428EHA Buenos Aires, Argentina; Fundación Instituto Leloir, C1405BWE Buenos Aires, Argentina
| | - Anabella Srebrow
- Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE-CONICET), Ciudad Universitaria Pabellón II, C1428EHA Buenos Aires, Argentina
| | - Alberto R Kornblihtt
- Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE-CONICET), Ciudad Universitaria Pabellón II, C1428EHA Buenos Aires, Argentina.
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Naftelberg S, Schor IE, Ast G, Kornblihtt AR. Regulation of alternative splicing through coupling with transcription and chromatin structure. Annu Rev Biochem 2015; 84:165-98. [PMID: 26034889 DOI: 10.1146/annurev-biochem-060614-034242] [Citation(s) in RCA: 298] [Impact Index Per Article: 33.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Alternative precursor messenger RNA (pre-mRNA) splicing plays a pivotal role in the flow of genetic information from DNA to proteins by expanding the coding capacity of genomes. Regulation of alternative splicing is as important as regulation of transcription to determine cell- and tissue-specific features, normal cell functioning, and responses of eukaryotic cells to external cues. Its importance is confirmed by the evolutionary conservation and diversification of alternative splicing and the fact that its deregulation causes hereditary disease and cancer. This review discusses the multiple layers of cotranscriptional regulation of alternative splicing in which chromatin structure, DNA methylation, histone marks, and nucleosome positioning play a fundamental role in providing a dynamic scaffold for interactions between the splicing and transcription machineries. We focus on evidence for how the kinetics of RNA polymerase II (RNAPII) elongation and the recruitment of splicing factors and adaptor proteins to chromatin components act in coordination to regulate alternative splicing.
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Affiliation(s)
- Shiran Naftelberg
- Sackler Medical School, Tel Aviv University, Tel Aviv 69978, Israel;
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18
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Chromatin, DNA structure and alternative splicing. FEBS Lett 2015; 589:3370-8. [PMID: 26296319 DOI: 10.1016/j.febslet.2015.08.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Revised: 07/31/2015] [Accepted: 08/04/2015] [Indexed: 02/07/2023]
Abstract
Coupling of transcription and alternative splicing via regulation of the transcriptional elongation rate is a well-studied phenomenon. Template features that act as roadblocks for the progression of RNA polymerase II comprise histone modifications and variants, DNA-interacting proteins and chromatin compaction. These may affect alternative splicing decisions by inducing pauses or decreasing elongation rate that change the time-window for splicing regulatory sequences to be recognized. Herein we discuss the evidence supporting the influence of template structural modifications on transcription and splicing, and provide insights about possible roles of non-B DNA conformations on the regulation of alternative splicing.
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19
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DNA-Encoded Chromatin Structural Intron Boundary Signals Identify Conserved Genes with Common Function. Int J Genomics 2015; 2015:167578. [PMID: 25861617 PMCID: PMC4377520 DOI: 10.1155/2015/167578] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 02/15/2015] [Indexed: 12/14/2022] Open
Abstract
The regulation of metazoan gene expression occurs in part by pre-mRNA splicing into mature RNAs. Signals affecting the efficiency and specificity with which introns are removed have not been completely elucidated. Splicing likely occurs cotranscriptionally, with chromatin structure playing a key regulatory role. We calculated DNA encoded nucleosome occupancy likelihood (NOL) scores at the boundaries between introns and exons across five metazoan species. We found that (i) NOL scores reveal a sequence-based feature at the introns on both sides of the intron-exon boundary; (ii) this feature is not part of any recognizable consensus sequence; (iii) this feature is conserved throughout metazoa; (iv) this feature is enriched in genes sharing similar functions: ATPase activity, ATP binding, helicase activity, and motor activity; (v) genes with these functions exhibit different genomic characteristics;
(vi) in vivo nucleosome positioning data confirm ontological enrichment at this feature; and (vii) genes with this feature exhibit unique dinucleotide distributions at the intron-exon boundary. The NOL scores point toward a physical property of DNA that may play a role in the mechanism of pre-mRNA splicing. These results provide a foundation for identification of a new set of regulatory DNA elements involved in splicing regulation.
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20
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Dušková E, Hnilicová J, Staněk D. CRE promoter sites modulate alternative splicing via p300-mediated histone acetylation. RNA Biol 2014; 11:865-74. [PMID: 25019513 DOI: 10.4161/rna.29441] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Histone acetylation modulates alternative splicing of several hundred genes. Here, we tested the role of the histone acetyltransferase p300 in alternative splicing and showed that knockdown of p300 promotes inclusion of the fibronectin (FN1) alternative EDB exon. p300 associates with CRE sites in the promoter via the CREB transcription factor. We created mini-gene reporters driven by an artificial promoter containing CRE sites. Both deletion and mutation of the CRE site affected EDB alternative splicing in the same manner as p300 knockdown. Next we showed that p300 controls histone H4 acetylation along the FN1 gene. Consistently, p300 depletion and CRE deletion/mutation both reduced histone H4 acetylation on mini-gene reporters. Finally, we provide evidence that the effect of CRE inactivation on H4 acetylation and alternative splicing is counteracted by the inhibition of histone deacetylases. Together, these data suggest that histone acetylation could be one of the mechanisms how promoter and promoter binding proteins influence alternative splicing.
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Affiliation(s)
- Eva Dušková
- Department of RNA Biology, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Prague, Czech Republic; Faculty of Science, Charles University in Prague, Prague, Czech Republic
| | - Jarmila Hnilicová
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - David Staněk
- Department of RNA Biology, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Prague, Czech Republic
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21
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da Glória VG, Martins de Araújo M, Mafalda Santos A, Leal R, de Almeida SF, Carmo AM, Moreira A. T cell activation regulates CD6 alternative splicing by transcription dynamics and SRSF1. THE JOURNAL OF IMMUNOLOGY 2014; 193:391-9. [PMID: 24890719 DOI: 10.4049/jimmunol.1400038] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The T cell-surface glycoprotein CD6 is a modulator of cellular responses and has been implicated in several autoimmune diseases such as multiple sclerosis, rheumatoid arthritis, and psoriasis. During Ag presentation, CD6 is targeted to the immunological synapse in a ligand binding-dependent manner, in which CD6 domain 3 directly contacts CD166, expressed on the APC. T cell activation results in the induction of CD6Δd3, an alternatively spliced isoform that lacks the ligand-binding domain and thus no longer localizes at the immunological synapse. In this study, we investigated the molecular mechanisms regulating the expression of CD6Δd3 upon human primary T cell activation. Using chromatin immunoprecipitation, we observed an increase in RNA polymerase II occupancy along the CD6 gene and augmented CD6 transcription. We showed that activation leads to transcription-related chromatin modifications, revealed by higher CD6 acetylation levels. Modulation of chromatin conformation using a histone deacetylase inhibitor that increases transcription rate causes an increase of exon 5 skipping. We further showed that the splicing factor SRSF1 binds to a regulatory element in CD6 intron 4, activating exon 5 splicing and promoting exon 5 inclusion. Concomitant with T cell activation-induced exon 5 skipping, we observed a downregulation of SRSF1. Using RNA immunoprecipitation, we showed that in activated T cells, SRSF1 recruitment to the CD6 transcript is impaired by increased chromatin acetylation levels. We propose that upon T cell activation, SRSF1 becomes limiting, and its function in CD6 exon 5 splicing is countered by an increase in CD6 transcription, dependent on chromatin acetylation.
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Affiliation(s)
- Vânia G da Glória
- Grupo Regulação Genética, Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto 4150-180, Portugal
| | - Mafalda Martins de Araújo
- Grupo Activação Celular e Expressão Genética, Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto 4150-180, Portugal; Instituto de Investigação em Ciências da Vida e da Saude, Escola de Ciências da Saude, Universidade do Minho, Braga 4710-057, Portugal; ICVS/3B's Laboratório Associado, Braga/Guimarães 4806-909, Portugal
| | - Ana Mafalda Santos
- Grupo Activação Celular e Expressão Genética, Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto 4150-180, Portugal
| | - Rafaela Leal
- Grupo Regulação Genética, Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto 4150-180, Portugal
| | - Sérgio F de Almeida
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade Lisboa, Lisboa 1649-028, Portugal; and
| | - Alexandre M Carmo
- Grupo Activação Celular e Expressão Genética, Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto 4150-180, Portugal; Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto 4050-313, Portugal
| | - Alexandra Moreira
- Grupo Regulação Genética, Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto 4150-180, Portugal;
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Abstract
Over two decades ago, two isoforms of the type II procollagen gene (COL2A1) were discovered. These isoforms, named IIA and IIB, are generated in a developmentally-regulated manner by alternative splicing of exon 2. Chondroprogenitor cells synthesize predominantly IIA isoforms (containing exon 2) while differentiated chondrocytes produce mainly IIB transcripts (devoid of exon 2). Importantly, this IIA-to-IIB alternative splicing switch occurs only during chondrogenesis. More recently, two other isoforms have been reported (IIC and IID) that also involve splicing of exon 2; these findings highlight the complexities involving regulation of COL2A1 expression. The biological significance of why different isoforms of COL2A1 exist within the context of skeletal development and maintenance is still not completely understood. This review will provide current knowledge on COL2A1 isoform expression during chondrocyte differentiation and what is known about some of the mechanisms that control exon 2 alternative splicing. Utilization of mouse models to address the biological significance of Col2a1 alternative splicing in vivo will also be discussed. From the knowledge acquired to date, some new questions and concepts are now being proposed on the importance of Col2a1 alternative splicing in regulating extracellular matrix assembly and how this may subsequently affect cartilage and endochondral bone quality and function.
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Affiliation(s)
- Audrey McAlinden
- Department of Orthopaedic Surgery, Musculoskeletal Research Center, Washington University School of Medicine , St Louis, MO , USA
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23
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How slow RNA polymerase II elongation favors alternative exon skipping. Mol Cell 2014; 54:683-90. [PMID: 24793692 DOI: 10.1016/j.molcel.2014.03.044] [Citation(s) in RCA: 154] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Revised: 01/23/2014] [Accepted: 03/01/2014] [Indexed: 11/20/2022]
Abstract
Splicing is functionally coupled to transcription, linking the rate of RNA polymerase II (Pol II) elongation and the ability of splicing factors to recognize splice sites (ss) of various strengths. In most cases, slow Pol II elongation allows weak splice sites to be recognized, leading to higher inclusion of alternative exons. Using CFTR alternative exon 9 (E9) as a model, we show here that slowing down elongation can also cause exon skipping by promoting the recruitment of the negative factor ETR-3 onto the UG-repeat at E9 3' splice site, which displaces the constitutive splicing factor U2AF65 from the overlapping polypyrimidine tract. Weakening of E9 5' ss increases ETR-3 binding at the 3' ss and subsequent E9 skipping, whereas strengthening of the 5' ss usage has the opposite effect. This indicates that a delay in the cotranscriptional emergence of the 5' ss promotes ETR-3 recruitment and subsequent inhibition of E9 inclusion.
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24
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Napolitano G, Lania L, Majello B. RNA polymerase II CTD modifications: how many tales from a single tail. J Cell Physiol 2014; 229:538-44. [PMID: 24122273 DOI: 10.1002/jcp.24483] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Accepted: 09/30/2013] [Indexed: 12/31/2022]
Abstract
Eukaryote's RNA polymerases II (RNAPII) have the feature to contain, at the carbossi-terminal region of their largest subunit Rpb1, a unique CTD domain. Rpb1-CTD is composed of an increasing number of repetitions of the Y1 S2 P3 T4 S5 P6 S7 heptad that goes in parallel with the developmental level of organisms. Because of its composition, the CTD domain has a huge structural plasticity; virtually all the residues can be subjected to post-translational modifications and the two prolines can either be in cis or trans conformations. In light of these features, it is reasonable to think that different specific nuances of CTD modification and interacting factors take place not only on different gene promoters but also during different stages of the transcription cycle and reasonably might have a role even if the polymerase is on or off the DNA template. Rpb1-CTD domain is involved not only in regulating transcriptional rates, but also in all co-transcriptional processes, such as pre-mRNA processing, splicing, cleavage, and export. Moreover, recent studies highlight a role of CTD in DNA replication and in maintenance of genomic stability and specific CTD-modifications have been related to different CTD functions. In this paper, we examine results from the most recent CTD-related literature and give an overview of the general function of Rpb1-CTD in transcription, transcription-related and non transcription-related processes in which it has been recently shown to be involved in.
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25
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Ge Y, Porse BT. The functional consequences of intron retention: alternative splicing coupled to NMD as a regulator of gene expression. Bioessays 2013; 36:236-43. [PMID: 24352796 DOI: 10.1002/bies.201300156] [Citation(s) in RCA: 133] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The explosion in sequencing technologies has provided us with an instrument to describe mammalian transcriptomes at unprecedented depths. This has revealed that alternative splicing is used extensively not only to generate protein diversity, but also as a means to regulate gene expression post-transcriptionally. Intron retention (IR) is overwhelmingly perceived as an aberrant splicing event with little or no functional consequence. However, recent work has now shown that IR is used to regulate a specific differentiation event within the haematopoietic system by coupling it to nonsense-mediated mRNA decay (NMD). Here, we highlight how IR and, more broadly, alternative splicing coupled to NMD (AS-NMD) can be used to regulate gene expression and how this is deregulated in disease. We suggest that the importance of AS-NMD is not restricted to the haematopoietic system but that it plays a prominent role in other normal and aberrant biological settings.
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Affiliation(s)
- Ying Ge
- The Finsen Laboratory, Rigshospitalet, Faculty of Health Sciences, University of Copenhagen, Denmark; Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Copenhagen, Denmark; Danish Stem Cell Centre (DanStem), Faculty of Health Sciences, University of Copenhagen, Denmark
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26
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Khan DH, Gonzalez C, Cooper C, Sun JM, Chen HY, Healy S, Xu W, Smith KT, Workman JL, Leygue E, Davie JR. RNA-dependent dynamic histone acetylation regulates MCL1 alternative splicing. Nucleic Acids Res 2013; 42:1656-70. [PMID: 24234443 PMCID: PMC3919583 DOI: 10.1093/nar/gkt1134] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Histone deacetylases (HDACs) and lysine acetyltransferases (KATs) catalyze dynamic histone acetylation at regulatory and coding regions of transcribed genes. Highly phosphorylated HDAC2 is recruited within corepressor complexes to regulatory regions, while the nonphosphorylated form is associated with the gene body. In this study, we characterized the nonphosphorylated HDAC2 complexes recruited to the transcribed gene body and explored the function of HDAC-complex-mediated dynamic histone acetylation. HDAC1 and 2 were coimmunoprecipitated with several splicing factors, including serine/arginine-rich splicing factor 1 (SRSF1) which has roles in alternative splicing. The co-chromatin immunoprecipitation of HDAC1/2 and SRSF1 to the gene body was RNA-dependent. Inhibition of HDAC activity and knockdown of HDAC1, HDAC2 or SRSF1 showed that these proteins were involved in alternative splicing of MCL1. HDAC1/2 and KAT2B were associated with nascent pre-mRNA in general and with MCL1 pre-mRNA specifically. Inhibition of HDAC activity increased the occupancy of KAT2B and acetylation of H3 and H4 of the H3K4 methylated alternative MCL1 exon 2 nucleosome. Thus, nonphosphorylated HDAC1/2 is recruited to pre-mRNA by splicing factors to act at the RNA level with KAT2B and other KATs to catalyze dynamic histone acetylation of the MCL1 alternative exon and alter the splicing of MCL1 pre-mRNA.
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Affiliation(s)
- Dilshad H Khan
- Department of Biochemistry and Medical Genetics, University of Manitoba, Manitoba Institute of Child Health, Winnipeg, Manitoba, R3E 3P4, Canada, Department of Biochemistry and Medical Genetics, University of Manitoba, Manitoba Institute of Cell Biology, Winnipeg, Manitoba, R3E0V9, Canada and Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA
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27
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Simon JM, Hacker KE, Singh D, Brannon AR, Parker JS, Weiser M, Ho TH, Kuan PF, Jonasch E, Furey TS, Prins JF, Lieb JD, Rathmell WK, Davis IJ. Variation in chromatin accessibility in human kidney cancer links H3K36 methyltransferase loss with widespread RNA processing defects. Genome Res 2013; 24:241-50. [PMID: 24158655 PMCID: PMC3912414 DOI: 10.1101/gr.158253.113] [Citation(s) in RCA: 137] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Comprehensive sequencing of human cancers has identified recurrent mutations in genes encoding chromatin regulatory proteins. For clear cell renal cell carcinoma (ccRCC), three of the five commonly mutated genes encode the chromatin regulators PBRM1, SETD2, and BAP1. How these mutations alter the chromatin landscape and transcriptional program in ccRCC or other cancers is not understood. Here, we identified alterations in chromatin organization and transcript profiles associated with mutations in chromatin regulators in a large cohort of primary human kidney tumors. By associating variation in chromatin organization with mutations in SETD2, which encodes the enzyme responsible for H3K36 trimethylation, we found that changes in chromatin accessibility occurred primarily within actively transcribed genes. This increase in chromatin accessibility was linked with widespread alterations in RNA processing, including intron retention and aberrant splicing, affecting ∼25% of all expressed genes. Furthermore, decreased nucleosome occupancy proximal to misspliced exons was observed in tumors lacking H3K36me3. These results directly link mutations in SETD2 to chromatin accessibility changes and RNA processing defects in cancer. Detecting the functional consequences of specific mutations in chromatin regulatory proteins in primary human samples could ultimately inform the therapeutic application of an emerging class of chromatin-targeted compounds.
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Affiliation(s)
- Jeremy M Simon
- Department of Genetics, University of North Carolina, Chapel Hill, North Carolina 27514, USA
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28
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Lopez-Mejia IC, De Toledo M, Della Seta F, Fafet P, Rebouissou C, Deleuze V, Blanchard JM, Jorgensen C, Tazi J, Vignais ML. Tissue-specific and SRSF1-dependent splicing of fibronectin, a matrix protein that controls host cell invasion. Mol Biol Cell 2013; 24:3164-76. [PMID: 23966470 PMCID: PMC3806663 DOI: 10.1091/mbc.e13-03-0142] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Matching sets of human primary fibroblasts cocultured with placenta explants are used to compare tissue capacities to support trophoblast invasion. Substituting endometrium with dermis dramatically reduces EVCT interstitial invasion, a phenomenon related to the ECM fibronectin content, FN alternative splicing, and expression of the SR protein SRSF1. Cell invasion targets specific tissues in physiological placental implantation and pathological metastasis, which raises questions about how this process is controlled. We compare dermis and endometrium capacities to support trophoblast invasion, using matching sets of human primary fibroblasts in a coculture assay with human placental explants. Substituting endometrium, the natural trophoblast target, with dermis dramatically reduces trophoblast interstitial invasion. Our data reveal that endometrium expresses a higher rate of the fibronectin (FN) extra type III domain A+ (EDA+) splicing isoform, which displays stronger matrix incorporation capacity. We demonstrate that the high FN content of the endometrium matrix, and not specifically the EDA domain, supports trophoblast invasion by showing that forced incorporation of plasma FN (EDA–) promotes efficient trophoblast invasion. We further show that the serine/arginine-rich protein serine/arginine-rich splicing factor 1 (SRSF1) is more highly expressed in endometrium and, using RNA interference, that it is involved in the higher EDA exon inclusion rate in endometrium. Our data therefore show a mechanism by which tissues can be distinguished, for their capacity to support invasion, by their different rates of EDA inclusion, linked to their SRSF1 protein levels. In the broader context of cancer pathology, the results suggest that SRSF1 might play a central role not only in the tumor cells, but also in the surrounding stroma.
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Affiliation(s)
- Isabel Cristina Lopez-Mejia
- Institut de Génétique Moléculaire de Montpellier, CNRS UMR 5535/IFR122, Universities of Montpellier 1 and Montpellier 2, 34293 Montpellier Cedex 5, France Département de Physiologie, Université de Lausanne, CH-1015 Lausanne, Switzerland INSERM U844, Institut des Neurosciences de Montpellier, Centre Hospitalier Universitaire Saint Eloi, Université Montpellier 1, 34295 Montpellier Cedex 5, France Service Immuno-Rhumatologie, Centre Hospitalier Universitaire Lapeyronie, 34093 Montpellier Cedex, France
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Schor IE, Fiszbein A, Petrillo E, Kornblihtt AR. Intragenic epigenetic changes modulate NCAM alternative splicing in neuronal differentiation. EMBO J 2013; 32:2264-74. [PMID: 23892457 DOI: 10.1038/emboj.2013.167] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Accepted: 06/28/2013] [Indexed: 12/19/2022] Open
Abstract
Alternative splicing contributes to cell type-specific transcriptomes. Here, we show that changes in intragenic chromatin marks affect NCAM (neural cell adhesion molecule) exon 18 (E18) alternative splicing during neuronal differentiation. An increase in the repressive marks H3K9me2 and H3K27me3 along the gene body correlated with inhibition of polymerase II elongation in the E18 region, but without significantly affecting total mRNA levels. Treatment with the general DNA methylation inhibitor 5-azacytidine and BIX 01294, a specific inhibitor of H3K9 dimethylation, inhibited the differentiation-induced E18 inclusion, pointing to a role for repressive marks in sustaining NCAM splicing patterns typical of mature neurons. We demonstrate that intragenic deployment of repressive chromatin marks, induced by intronic small interfering RNAs targeting NCAM intron 18, promotes E18 inclusion in undifferentiated N2a cells, confirming the chromatin changes observed upon differentiation to be sufficient to induce alternative splicing. Combined with previous evidence that neuronal depolarization causes H3K9 acetylation and subsequent E18 skipping, our results show how two alternative epigenetic marks regulate NCAM alternative splicing and E18 levels in different cellular contexts.
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Affiliation(s)
- Ignacio E Schor
- Laboratorio de Fisiología y Biología Molecular, Departamento de Fisiología, Biología Molecular y Celular, IFIBYNE-UBA-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, Argentina
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30
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Mechanisms of the androgen receptor splicing in prostate cancer cells. Oncogene 2013; 33:3140-50. [PMID: 23851510 DOI: 10.1038/onc.2013.284] [Citation(s) in RCA: 223] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2013] [Revised: 06/12/2013] [Accepted: 06/14/2013] [Indexed: 12/25/2022]
Abstract
Prostate tumors develop resistance to androgen deprivation therapy (ADT) by multiple mechanisms, one of which is to express constitutively active androgen receptor (AR) splice variants lacking the ligand-binding domain. AR splice variant 7 (AR-V7, also termed AR3) is the most abundantly expressed variant that drives prostate tumor progression under ADT conditions. However, the molecular mechanism by which AR-V7 is generated remains unclear. In this manuscript, we demonstrated that RNA splicing of AR-V7 in response to ADT was closely associated with AR gene transcription initiation and elongation rates. Enhanced AR gene transcription by ADT provides a prerequisite condition that further increases the interactions between AR pre-mRNA and splicing factors. Under ADT conditions, recruitment of several RNA splicing factors to the 3' splicing site for AR-V7 was increased. We identified two RNA splicing enhancers and their binding proteins (U2AF65 and ASF/SF2) that had critical roles in splicing AR pre-mRNA into AR-V7. These data indicate that ADT-induced AR gene transcription rate and splicing factor recruitment to AR pre-mRNA contribute to the enhanced AR-V7 levels in prostate cancer cells.
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Kornblihtt AR, Schor IE, Alló M, Dujardin G, Petrillo E, Muñoz MJ. Alternative splicing: a pivotal step between eukaryotic transcription and translation. Nat Rev Mol Cell Biol 2013; 14:153-65. [PMID: 23385723 DOI: 10.1038/nrm3525] [Citation(s) in RCA: 569] [Impact Index Per Article: 51.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Alternative splicing was discovered simultaneously with splicing over three decades ago. Since then, an enormous body of evidence has demonstrated the prevalence of alternative splicing in multicellular eukaryotes, its key roles in determining tissue- and species-specific differentiation patterns, the multiple post- and co-transcriptional regulatory mechanisms that control it, and its causal role in hereditary disease and cancer. The emerging evidence places alternative splicing in a central position in the flow of eukaryotic genetic information, between transcription and translation, in that it can respond not only to various signalling pathways that target the splicing machinery but also to transcription factors and chromatin structure.
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Affiliation(s)
- Alberto R Kornblihtt
- Departamento de Fisiología, Biología Molecular y Celular e Instituto de Fisiología, Biología Molecular y Neurociencias, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, C1428EHA Buenos Aires, Argentina.
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Deep sequencing of subcellular RNA fractions shows splicing to be predominantly co-transcriptional in the human genome but inefficient for lncRNAs. Genome Res 2013; 22:1616-25. [PMID: 22955974 PMCID: PMC3431479 DOI: 10.1101/gr.134445.111] [Citation(s) in RCA: 314] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Splicing remains an incompletely understood process. Recent findings suggest that chromatin structure participates in its regulation. Here, we analyze the RNA from subcellular fractions obtained through RNA-seq in the cell line K562. We show that in the human genome, splicing occurs predominantly during transcription. We introduce the coSI measure, based on RNA-seq reads mapping to exon junctions and borders, to assess the degree of splicing completion around internal exons. We show that, as expected, splicing is almost fully completed in cytosolic polyA+ RNA. In chromatin-associated RNA (which includes the RNA that is being transcribed), for 5.6% of exons, the removal of the surrounding introns is fully completed, compared with 0.3% of exons for which no intron-removal has occurred. The remaining exons exist as a mixture of spliced and fewer unspliced molecules, with a median coSI of 0.75. Thus, most RNAs undergo splicing while being transcribed: “co-transcriptional splicing.” Consistent with co-transcriptional spliceosome assembly and splicing, we have found significant enrichment of spliceosomal snRNAs in chromatin-associated RNA compared with other cellular RNA fractions and other nonspliceosomal snRNAs. CoSI scores decrease along the gene, pointing to a “first transcribed, first spliced” rule, yet more downstream exons carry other characteristics, favoring rapid, co-transcriptional intron removal. Exons with low coSI values, that is, in the process of being spliced, are enriched with chromatin marks, consistent with a role for chromatin in splicing during transcription. For alternative exons and long noncoding RNAs, splicing tends to occur later, and the latter might remain unspliced in some cases.
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Schor IE, Gómez Acuña LI, Kornblihtt AR. Coupling between transcription and alternative splicing. Cancer Treat Res 2013; 158:1-24. [PMID: 24222352 DOI: 10.1007/978-3-642-31659-3_1] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The scenario of alternative splicing regulation is far more complex than the classical picture of a pre-mRNA being processed post-transcriptionally in more than one way. Introns are efficiently removed while transcripts are still being synthesized, supporting the idea of a co-transcriptional regulation of alternative splicing. Evidence of a functional coupling between splicing and transcription has recently emerged as it was observed that properties of one process may affect the outcome of the other. Co-transcriptionality is thought to improve splicing efficiency and kinetics by directing the nascent pre-mRNA into proper spliceosome assembly and favoring splicing factor recruitment. Two models have been proposed to explain the coupling of transcription and alternative splicing: in the recruitment model, promoters and pol II status affect the recruitment to the transcribing gene of splicing factors or bifunctional factors acting on both transcription and splicing; in the kinetic model, differences in the elongation rate of pol II would determine the timing in which splicing sites are presented, and thus the outcome of alternative splicing decisions. In the later model, chromatin structure has emerged as a key regulator. Although definitive evidence for transcriptionally coupled alternative splicing alterations in tumor development or cancer pathogenesis is still missing, many alternative splicing events altered in cancer might be subject to transcription-splicing coupling regulation.
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Affiliation(s)
- Ignacio E Schor
- Laboratorio de Fisiologia y Biologia Molecular, Departmento de Fisiologia, Biologia Molecular y Celular, IFIBYNE-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, PAB. II, 20 Piso, Buenos Aires, 1428, Argentina
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Khodor YL, Menet JS, Tolan M, Rosbash M. Cotranscriptional splicing efficiency differs dramatically between Drosophila and mouse. RNA (NEW YORK, N.Y.) 2012; 18:2174-86. [PMID: 23097425 PMCID: PMC3504670 DOI: 10.1261/rna.034090.112] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Spliceosome assembly and/or splicing of a nascent transcript may be crucial for proper isoform expression and gene regulation in higher eukaryotes. We recently showed that cotranscriptional splicing occurs efficiently in Drosophila, but there are not comparable genome-wide nascent splicing data from mammals. To provide this comparison, we analyze a recently generated, high-throughput sequencing data set of mouse liver nascent RNA, originally studied for circadian transcriptional regulation. Cotranscriptional splicing is approximately twofold less efficient in mouse liver than in Drosophila, i.e., nascent intron levels relative to exon levels are ∼0.55 in mouse versus 0.25 in the fly. An additional difference between species is that only mouse cotranscriptional splicing is optimal when 5'-exon length is between 50 and 500 bp, and intron length does not correlate with splicing efficiency, consistent with exon definition. A similar analysis of intron and exon length dependence in the fly is more consistent with intron definition. Contrasted with these differences are many similarities between the two systems: Alternatively annotated introns are less efficiently spliced cotranscriptionally than constitutive introns, and introns of single-intron genes are less efficiently spliced than introns from multi-intron genes. The most striking common feature is intron position: Cotranscriptional splicing is much more efficient when introns are far from the 3' ends of their genes. Additionally, absolute gene length correlates positively with cotranscriptional splicing efficiency independently of intron location and position, in flies as well as in mice. The gene length and distance effects indicate that more "nascent time" gives rise to greater cotranscriptional splicing efficiency in both systems.
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Affiliation(s)
- Yevgenia L. Khodor
- Howard Hughes Medical Institute and National Center for Behavioral Genomics, Department of Biology, Brandeis University, Waltham, Massachusetts 02454, USA
| | - Jerome S. Menet
- Howard Hughes Medical Institute and National Center for Behavioral Genomics, Department of Biology, Brandeis University, Waltham, Massachusetts 02454, USA
| | - Michael Tolan
- Howard Hughes Medical Institute and National Center for Behavioral Genomics, Department of Biology, Brandeis University, Waltham, Massachusetts 02454, USA
| | - Michael Rosbash
- Howard Hughes Medical Institute and National Center for Behavioral Genomics, Department of Biology, Brandeis University, Waltham, Massachusetts 02454, USA
- Corresponding authorE-mail
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Lenasi T, Barboric M. Mutual relationships between transcription and pre-mRNA processing in the synthesis of mRNA. WILEY INTERDISCIPLINARY REVIEWS-RNA 2012. [PMID: 23184646 DOI: 10.1002/wrna.1148] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The generation of messenger RNA (mRNA) in eukaryotes is achieved by transcription from the DNA template and pre-mRNA processing reactions of capping, splicing, and polyadenylation. Although RNA polymerase II (RNAPII) catalyzes the synthesis of pre-mRNA, it also serves as a principal coordinator of the processing reactions in the course of transcription. In this review, we focus on the interplay between transcription and cotranscriptional pre-mRNA maturation events, mediated by the recruitment of RNA processing factors to differentially phosphorylated C-terminal domain of Rbp1, the largest subunit of RNAPII. Furthermore, we highlight the bidirectional nature of the interplay by discussing the impact of RNAPII kinetics on pre-mRNA processing as well as how the processing events reach back to different phases of gene transcription.
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Affiliation(s)
- Tina Lenasi
- Institute of Biomedicine, Biochemistry and Developmental Biology, University of Helsinki, Helsinki, Finland.
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Schor IE, Llères D, Risso GJ, Pawellek A, Ule J, Lamond AI, Kornblihtt AR. Perturbation of chromatin structure globally affects localization and recruitment of splicing factors. PLoS One 2012; 7:e48084. [PMID: 23152763 PMCID: PMC3495951 DOI: 10.1371/journal.pone.0048084] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Accepted: 09/19/2012] [Indexed: 12/02/2022] Open
Abstract
Chromatin structure is an important factor in the functional coupling between transcription and mRNA processing, not only by regulating alternative splicing events, but also by contributing to exon recognition during constitutive splicing. We observed that depolarization of neuroblastoma cell membrane potential, which triggers general histone acetylation and regulates alternative splicing, causes a concentration of SR proteins in nuclear speckles. This prompted us to analyze the effect of chromatin structure on splicing factor distribution and dynamics. Here, we show that induction of histone hyper-acetylation results in the accumulation in speckles of multiple splicing factors in different cell types. In addition, a similar effect is observed after depletion of the heterochromatic protein HP1α, associated with repressive chromatin. We used advanced imaging approaches to analyze in detail both the structural organization of the speckle compartment and nuclear distribution of splicing factors, as well as studying direct interactions between splicing factors and their association with chromatin in vivo. The results support a model where perturbation of normal chromatin structure decreases the recruitment efficiency of splicing factors to nascent RNAs, thus causing their accumulation in speckles, which buffer the amount of free molecules in the nucleoplasm. To test this, we analyzed the recruitment of the general splicing factor U2AF65 to nascent RNAs by iCLIP technique, as a way to monitor early spliceosome assembly. We demonstrate that indeed histone hyper-acetylation decreases recruitment of U2AF65 to bulk 3′ splice sites, coincident with the change in its localization. In addition, prior to the maximum accumulation in speckles, ∼20% of genes already show a tendency to decreased binding, while U2AF65 seems to increase its binding to the speckle-located ncRNA MALAT1. All together, the combined imaging and biochemical approaches support a model where chromatin structure is essential for efficient co-transcriptional recruitment of general and regulatory splicing factors to pre-mRNA.
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Affiliation(s)
- Ignacio E. Schor
- Laboratorio de Fisiología y Biología Molecular, Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Instituto de Fisiología, Biología Molecular y Neurociencias, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - David Llères
- Dundee Centre for Gene Regulation and Expression, University of Dundee, Dundee, Scotland, United Kingdom
| | - Guillermo J. Risso
- Laboratorio de Fisiología y Biología Molecular, Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Instituto de Fisiología, Biología Molecular y Neurociencias, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - Andrea Pawellek
- Dundee Centre for Gene Regulation and Expression, University of Dundee, Dundee, Scotland, United Kingdom
| | - Jernej Ule
- Laboratory of Molecular Biology, Medical Research Council, Cambridge, England, United Kingdom
| | - Angus I. Lamond
- Dundee Centre for Gene Regulation and Expression, University of Dundee, Dundee, Scotland, United Kingdom
| | - Alberto R. Kornblihtt
- Laboratorio de Fisiología y Biología Molecular, Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Instituto de Fisiología, Biología Molecular y Neurociencias, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
- * E-mail:
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Gómez Acuña LI, Fiszbein A, Alló M, Schor IE, Kornblihtt AR. Connections between chromatin signatures and splicing. WILEY INTERDISCIPLINARY REVIEWS-RNA 2012; 4:77-91. [PMID: 23074139 DOI: 10.1002/wrna.1142] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Splicing and alternative splicing are involved in the expression of most human genes, playing key roles in differentiation, cell cycle progression, and development. Misregulation of splicing is frequently associated to disease, which imposes a better understanding of the mechanisms underlying splicing regulation. Accumulated evidence suggests that multiple trans-acting factors and cis-regulatory elements act together to determine tissue-specific splicing patterns. Besides, as splicing is often cotranscriptional, a complex picture emerges in which splicing regulation not only depends on the balance of splicing factor binding to their pre-mRNA target sites but also on transcription-associated features such as protein recruitment to the transcribing machinery and elongation kinetics. Adding more complexity to the splicing regulation network, recent evidence shows that chromatin structure is another layer of regulation that may act through various mechanisms. These span from regulation of RNA polymerase II elongation, which ultimately determines splicing decisions, to splicing factor recruitment by specific histone marks. Chromatin may not only be involved in alternative splicing regulation but in constitutive exon recognition as well. Moreover, splicing was found to be necessary for the proper 'writing' of particular chromatin signatures, giving further mechanistic support to functional interconnections between splicing, transcription and chromatin structure. These links between chromatin configuration and splicing raise the intriguing possibility of the existence of a memory for splicing patterns to be inherited through epigenetic modifications.
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Affiliation(s)
- Luciana I Gómez Acuña
- Laboratorio de Fisiología y Biología Molecular, Departamento de Fisiología, Biología Molecular y Celular, IFIBYNE-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, Argentina
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38
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Dujardin G, Lafaille C, Petrillo E, Buggiano V, Gómez Acuña LI, Fiszbein A, Godoy Herz MA, Nieto Moreno N, Muñoz MJ, Alló M, Schor IE, Kornblihtt AR. Transcriptional elongation and alternative splicing. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2012; 1829:134-40. [PMID: 22975042 DOI: 10.1016/j.bbagrm.2012.08.005] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Revised: 08/23/2012] [Accepted: 08/29/2012] [Indexed: 12/29/2022]
Abstract
Alternative splicing has emerged as a key contributor to proteome diversity, highlighting the importance of understanding its regulation. In recent years it became apparent that splicing is predominantly cotranscriptional, allowing for crosstalk between these two nuclear processes. We discuss some of the links between transcription and splicing, with special emphasis on the role played by transcription elongation in the regulation of alternative splicing events and in particular the kinetic model of alternative splicing regulation. This article is part of a Special Issue entitled: RNA polymerase II Transcript Elongation.
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Affiliation(s)
- Gwendal Dujardin
- Departamento de Fisiología, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, Argentina
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Montes M, Becerra S, Sánchez-Álvarez M, Suñé C. Functional coupling of transcription and splicing. Gene 2012; 501:104-17. [DOI: 10.1016/j.gene.2012.04.006] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Revised: 04/02/2012] [Accepted: 04/05/2012] [Indexed: 01/13/2023]
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40
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Hnilicová J, Staněk D. Where splicing joins chromatin. Nucleus 2012; 2:182-8. [PMID: 21818411 DOI: 10.4161/nucl.2.3.15876] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2011] [Revised: 04/18/2011] [Accepted: 04/19/2011] [Indexed: 12/14/2022] Open
Abstract
There are numerous data suggesting that two key steps in gene expression-transcription and splicing influence each other closely. For a long time it was known that chromatin modifications regulate transcription, but only recently it was shown that chromatin and histone modifications play a significant role in pre-mRNA splicing. Here we summarize interactions between splicing machinery and chromatin and discuss their potential functional significance. We focus mainly on histone acetylation and methylation and potential mechanisms of their role in splicing. It seems that whereas histone acetylation acts mainly by alterating the transcription rate, histone methylation can also influence splicing directly by recruiting various splicing components.
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Affiliation(s)
- Jarmila Hnilicová
- Department of RNA Biology, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Prague
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41
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Khodor YL, Rodriguez J, Abruzzi KC, Tang CHA, Marr MT, Rosbash M. Nascent-seq indicates widespread cotranscriptional pre-mRNA splicing in Drosophila. Genes Dev 2012; 25:2502-12. [PMID: 22156210 DOI: 10.1101/gad.178962.111] [Citation(s) in RCA: 206] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
To determine the prevalence of cotranscriptional splicing in Drosophila, we sequenced nascent RNA transcripts from Drosophila S2 cells as well as from Drosophila heads. Eighty-seven percent of the introns assayed manifest >50% cotranscriptional splicing. The remaining 13% are cotranscriptionally spliced poorly or slowly, with ∼3% being almost completely retained in nascent pre-mRNA. Although individual introns showed slight but statistically significant differences in splicing efficiency, similar global levels of splicing were seen from both sources. Importantly, introns with low cotranscriptional splicing efficiencies are present in the same primary transcript with efficiently spliced introns, indicating that splicing is intron-specific. The analysis also indicates that cotranscriptional splicing is less efficient for first introns, longer introns, and introns annotated as alternative. Finally, S2 cells expressing the slow RpII215(C4) mutant show substantially less intron retention than wild-type S2 cells.
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Affiliation(s)
- Yevgenia L Khodor
- Howard Hughes Medical Institute, National Center for Behavioral Genomics, Brandeis University, Waltham, Massachusetts 02454, USA
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Vezf1 protein binding sites genome-wide are associated with pausing of elongating RNA polymerase II. Proc Natl Acad Sci U S A 2012; 109:2370-5. [PMID: 22308494 DOI: 10.1073/pnas.1121538109] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The protein Vezf1 plays multiple roles important for embryonic development. In Vezf1(-/-) mouse embryonic stem (mES) cells, our earlier data showed widespread changes in gene-expression profiles, including decreased expression of the full-length active isoform of Dnmt3b methyltransferase and concomitant genome-wide reduction in DNA methylation. Here we show that in HeLaS3 cells there is a strong genome-wide correlation between Vezf1 binding and peaks of elongating Ser2-P RNA polymerase (Pol) ll, reflecting Vezf1-dependent slowing of elongation. In WT mES cells, the elongating form of RNA pol II accumulates near Vezf1 binding sites within the dnmt3b gene and at several other Vezf1 sites, and this accumulation is significantly reduced at these sites in Vezf1(-/-) mES cells. Depending upon genomic location, Vezf1-mediated Pol II pausing can have different regulatory roles in transcription and splicing. We find examples of genes in which Vezf1 binding sites are located near cassette exons, and in which loss of Vezf1 leads to a change in the relative abundance of alternatively spliced messages. We further show that Vezf1 interacts with Mrg15/Mrgbp, a protein that recognizes H3K36 trimethylation, consistent with the role of histone modifications at alternatively spliced sites.
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44
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TCERG1 regulates alternative splicing of the Bcl-x gene by modulating the rate of RNA polymerase II transcription. Mol Cell Biol 2011; 32:751-62. [PMID: 22158966 DOI: 10.1128/mcb.06255-11] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Complex functional coupling exists between transcriptional elongation and pre-mRNA alternative splicing. Pausing sites and changes in the rate of transcription by RNA polymerase II (RNAPII) may therefore have fundamental impacts in the regulation of alternative splicing. Here, we show that the elongation and splicing-related factor TCERG1 regulates alternative splicing of the apoptosis gene Bcl-x in a promoter-dependent manner. TCERG1 promotes the splicing of the short isoform of Bcl-x (Bcl-x(s)) through the SB1 regulatory element located in the first half of exon 2. Consistent with these results, we show that TCERG1 associates with the Bcl-x pre-mRNA. A transcription profile analysis revealed that the RNA sequences required for the effect of TCERG1 on Bcl-x alternative splicing coincide with a putative polymerase pause site. Furthermore, TCERG1 modifies the impact of a slow polymerase on Bcl-x alternative splicing. In support of a role for an elongation mechanism in the transcriptional control of Bcl-x alternative splicing, we found that TCERG1 modifies the amount of pre-mRNAs generated at distal regions of the endogenous Bcl-x. Most importantly, TCERG1 affects the rate of RNAPII transcription of endogenous human Bcl-x. We propose that TCERG1 modulates the elongation rate of RNAPII to relieve pausing, thereby activating the proapoptotic Bcl-x(S) 5' splice site.
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45
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Bartkowiak B, Mackellar AL, Greenleaf AL. Updating the CTD Story: From Tail to Epic. GENETICS RESEARCH INTERNATIONAL 2011; 2011:623718. [PMID: 22567360 PMCID: PMC3335468 DOI: 10.4061/2011/623718] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2011] [Accepted: 08/10/2011] [Indexed: 12/03/2022]
Abstract
Eukaryotic RNA polymerase II (RNAPII) not only synthesizes mRNA but also coordinates transcription-related processes via its unique C-terminal repeat domain (CTD). The CTD is an RNAPII-specific protein segment consisting of repeating heptads with the consensus sequence Y1S2P3T4S5P6S7 that has been shown to be extensively post-transcriptionally modified in a coordinated, but complicated, manner. Recent discoveries of new modifications, kinases, and binding proteins have challenged previously established paradigms. In this paper, we examine results and implications of recent studies related to modifications of the CTD and the respective enzymes; we also survey characterizations of new CTD-binding proteins and their associated processes and new information regarding known CTD-binding proteins. Finally, we bring into focus new results that identify two additional CTD-associated processes: nucleocytoplasmic transport of mRNA and DNA damage and repair.
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Affiliation(s)
- Bartlomiej Bartkowiak
- Department of Biochemistry and Center for RNA Biology, Duke University Medical Center, Durham, NC 27710, USA
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Žumer K, Plemenitaš A, Saksela K, Peterlin BM. Patient mutation in AIRE disrupts P-TEFb binding and target gene transcription. Nucleic Acids Res 2011; 39:7908-19. [PMID: 21724609 PMCID: PMC3185428 DOI: 10.1093/nar/gkr527] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Revised: 06/06/2011] [Accepted: 06/08/2011] [Indexed: 01/17/2023] Open
Abstract
Autoimmune regulator (AIRE) is a transcription factor that induces the expression of a large subset of otherwise strictly tissue restricted antigens in medullary thymic epithelial cells, thereby enabling their presentation to developing T cells for negative selection. Mutations in AIRE lead to autoimmune-polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED), a rare monogenetic disease. Although it has been reported that AIRE interacts with proteins involved in nuclear transport, DNA-damage response, chromatin remodeling, transcription and pre-mRNA-splicing, the precise mechanism of AIRE-induced tissue restricted antigen expression has remained elusive. In this study, we investigated an APECED patient mutation that causes the loss of the extreme C-terminus of AIRE and found that this mutant protein is transcriptionaly inactive. When tethered heterologously to DNA, this domain could stimulate transcription and splicing by itself. Moreover, the loss of this C-terminus disrupted interactions with the positive transcription elongation factor b (P-TEFb). Via P-TEFb, AIRE increased levels of RNA polymerase II on and enhanced pre-mRNA splicing of heterologous and endogenous target genes. Indeed, the inhibition of CDK9, the kinase subunit of P-TEFb, inhibited AIRE-induced pre-mRNA splicing of these genes. Thus, AIRE requires P-TEFb to activate transcription elongation and co-transcriptional processing of target genes.
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Affiliation(s)
- Kristina Žumer
- Institute of Biochemistry, Faculty of Medicine, University of Ljubljana, Vrazov trg 2, 1000 Ljubljana, Slovenia, Department of Virology, Haartman Institute, University of Helsinki, Haartmaninkatu 3, 00290 Helsinki, Finland and Department of Medicine, Microbiology and Immunology, Rosalind Russell Medical Research Center, University of California San Francisco, 533 Parnassus Ave., San Francisco, CA 94143-070, USA
| | - Ana Plemenitaš
- Institute of Biochemistry, Faculty of Medicine, University of Ljubljana, Vrazov trg 2, 1000 Ljubljana, Slovenia, Department of Virology, Haartman Institute, University of Helsinki, Haartmaninkatu 3, 00290 Helsinki, Finland and Department of Medicine, Microbiology and Immunology, Rosalind Russell Medical Research Center, University of California San Francisco, 533 Parnassus Ave., San Francisco, CA 94143-070, USA
| | - Kalle Saksela
- Institute of Biochemistry, Faculty of Medicine, University of Ljubljana, Vrazov trg 2, 1000 Ljubljana, Slovenia, Department of Virology, Haartman Institute, University of Helsinki, Haartmaninkatu 3, 00290 Helsinki, Finland and Department of Medicine, Microbiology and Immunology, Rosalind Russell Medical Research Center, University of California San Francisco, 533 Parnassus Ave., San Francisco, CA 94143-070, USA
| | - B. Matija Peterlin
- Institute of Biochemistry, Faculty of Medicine, University of Ljubljana, Vrazov trg 2, 1000 Ljubljana, Slovenia, Department of Virology, Haartman Institute, University of Helsinki, Haartmaninkatu 3, 00290 Helsinki, Finland and Department of Medicine, Microbiology and Immunology, Rosalind Russell Medical Research Center, University of California San Francisco, 533 Parnassus Ave., San Francisco, CA 94143-070, USA
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de la Mata M, Muñoz MJ, Alló M, Fededa JP, Schor IE, Kornblihtt AR. RNA Polymerase II Elongation at the Crossroads of Transcription and Alternative Splicing. GENETICS RESEARCH INTERNATIONAL 2011; 2011:309865. [PMID: 22567350 PMCID: PMC3335476 DOI: 10.4061/2011/309865] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Accepted: 06/23/2011] [Indexed: 11/20/2022]
Abstract
The elongation phase of transcription lies at the core of several simultaneous and coupled events leading to alternative splicing regulation. Although underestimated in the past, it is at this phase of the transcription cycle where complexes affecting the transcription machinery itself, chromatin structure, posttranscriptional gene regulation and pre-mRNA processing converge to regulate each other or simply to consolidate higher-order complexes and functions. This paper focuses on the multiple processes that take place during transcription elongation which ultimately regulate the outcome of alternative splicing decisions.
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Affiliation(s)
- Manuel de la Mata
- Laboratorio de Fisiología y Biología Molecular, Departamento de Fisiología, Biología Molecular, y Celular, IFIBYNE-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, C1428EHA Buenos Aires, Argentina
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Stress-induced expression of p53 target genes is insensitive to SNW1/SKIP downregulation. Cell Mol Biol Lett 2011; 16:373-84. [PMID: 21461980 PMCID: PMC6275595 DOI: 10.2478/s11658-011-0012-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2010] [Accepted: 03/28/2011] [Indexed: 12/22/2022] Open
Abstract
Pharmacological inhibition of protein kinases that are responsible for the phosphorylation of the carboxy-terminal domain (CTD) of RNA Pol II during transcription by 5,6-dichloro-1-beta-D-ribofuranosyl-benzimidazole (DRB) leads to severe inhibition of mRNA synthesis and activates p53. Transcription of the p53 effectors that are induced under these conditions, such as p21 or PUMA, must bypass the requirement for CTD phosphorylation by the positive elongation factor P-TEFb. Here, we have downregulated SNW1/SKIP, a splicing factor and a transcriptional co-regulator, which was found to interact with P-TEFb and synergistically affect Tat-dependent transcription elongation of HIV 1. Using the colon cancer derived cell line HCT116, we have found that both doxorubicin- and DRB-induced expression of p21 or PUMA is insensitive to SNW1 downregulation by siRNA. This suggests that transcription of stress response genes, unlike, e.g., the SNW1-sensitive mitosis-specific genes, can proceed uncoupled from regulators that normally function under physiological conditions.
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Luco RF, Allo M, Schor IE, Kornblihtt AR, Misteli T. Epigenetics in alternative pre-mRNA splicing. Cell 2011; 144:16-26. [PMID: 21215366 DOI: 10.1016/j.cell.2010.11.056] [Citation(s) in RCA: 582] [Impact Index Per Article: 44.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2010] [Revised: 09/07/2010] [Accepted: 11/13/2010] [Indexed: 12/11/2022]
Abstract
Alternative splicing plays critical roles in differentiation, development, and disease and is a major source for protein diversity in higher eukaryotes. Analysis of alternative splicing regulation has traditionally focused on RNA sequence elements and their associated splicing factors, but recent provocative studies point to a key function of chromatin structure and histone modifications in alternative splicing regulation. These insights suggest that epigenetic regulation determines not only what parts of the genome are expressed but also how they are spliced.
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Affiliation(s)
- Reini F Luco
- National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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Alexander RD, Innocente SA, Barrass JD, Beggs JD. Splicing-dependent RNA polymerase pausing in yeast. Mol Cell 2010; 40:582-93. [PMID: 21095588 PMCID: PMC3000496 DOI: 10.1016/j.molcel.2010.11.005] [Citation(s) in RCA: 201] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2010] [Revised: 07/20/2010] [Accepted: 09/29/2010] [Indexed: 11/19/2022]
Abstract
In eukaryotic cells, there is evidence for functional coupling between transcription and processing of pre-mRNAs. To better understand this coupling, we performed a high-resolution kinetic analysis of transcription and splicing in budding yeast. This revealed that shortly after induction of transcription, RNA polymerase accumulates transiently around the 3′ end of the intron on two reporter genes. This apparent transcriptional pause coincides with splicing factor recruitment and with the first detection of spliced mRNA and is repeated periodically thereafter. Pausing requires productive splicing, as it is lost upon mutation of the intron and restored by suppressing the splicing defect. The carboxy-terminal domain of the paused polymerase large subunit is hyperphosphorylated on serine 5, and phosphorylation of serine 2 is first detected here. Phosphorylated polymerase also accumulates around the 3′ splice sites of constitutively expressed, endogenous yeast genes. We propose that transcriptional pausing is imposed by a checkpoint associated with cotranscriptional splicing.
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Affiliation(s)
- Ross D. Alexander
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, King's Buildings, Edinburgh EH9 3JR, UK
- Edinburgh Centre for Systems Biology, University of Edinburgh, King's Buildings, Edinburgh EH9 3JR, UK
| | - Steven A. Innocente
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, King's Buildings, Edinburgh EH9 3JR, UK
- Edinburgh Centre for Systems Biology, University of Edinburgh, King's Buildings, Edinburgh EH9 3JR, UK
| | - J. David Barrass
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, King's Buildings, Edinburgh EH9 3JR, UK
- Edinburgh Centre for Systems Biology, University of Edinburgh, King's Buildings, Edinburgh EH9 3JR, UK
| | - Jean D. Beggs
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, King's Buildings, Edinburgh EH9 3JR, UK
- Edinburgh Centre for Systems Biology, University of Edinburgh, King's Buildings, Edinburgh EH9 3JR, UK
- Corresponding author
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