1
|
Bao N, Wang Z, Fu J, Dong H, Jin Y. RNA structure in alternative splicing regulation: from mechanism to therapy. Acta Biochim Biophys Sin (Shanghai) 2024. [PMID: 39034824 DOI: 10.3724/abbs.2024119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/23/2024] Open
Abstract
Alternative splicing is a highly intricate process that plays a crucial role in post-transcriptional regulation and significantly expands the functional proteome of a limited number of coding genes in eukaryotes. Its regulation is multifactorial, with RNA structure exerting a significant impact. Aberrant RNA conformations lead to dysregulation of splicing patterns, which directly affects the manifestation of disease symptoms. In this review, the molecular mechanisms of RNA secondary structure-mediated splicing regulation are summarized, with a focus on the complex interplay between aberrant RNA conformations and disease phenotypes resulted from splicing defects. This study also explores additional factors that reshape structural conformations, enriching our understanding of the mechanistic network underlying structure-mediated splicing regulation. In addition, an emphasis has been placed on the clinical role of targeting aberrant splicing corrections in human diseases. The principal mechanisms of action behind this phenomenon are described, followed by a discussion of prospective development strategies and pertinent challenges.
Collapse
|
2
|
Borao S, Vega M, Boronat S, Hidalgo E, Hümmer S, Ayté J. A systematic screen identifies Saf5 as a link between splicing and transcription in fission yeast. PLoS Genet 2024; 20:e1011316. [PMID: 38833506 PMCID: PMC11178228 DOI: 10.1371/journal.pgen.1011316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Revised: 06/14/2024] [Accepted: 05/23/2024] [Indexed: 06/06/2024] Open
Abstract
Splicing is an important step of gene expression regulation in eukaryotes, as there are many mRNA precursors that can be alternatively spliced in different tissues, at different cell cycle phases or under different external stimuli. We have developed several integrated fluorescence-based in vivo splicing reporter constructs that allow the quantification of fission yeast splicing in vivo on intact cells, and we have compared their splicing efficiency in a wild type strain and in a prp2-1 (U2AF65) genetic background, showing a clear dependency between Prp2 and a consensus signal at 5' splicing site (5'SS). To isolate novel genes involved in regulated splicing, we have crossed the reporter showing more intron retention with the Schizosaccharomyces pombe knock out collection. Among the candidate genes involved in the regulation of splicing, we have detected strong splicing defects in two of the mutants -Δcwf12, a member of the NineTeen Complex (NTC) and Δsaf5, a methylosome subunit that acts together with the survival motor neuron (SMN) complex in small nuclear ribonucleoproteins (snRNP) biogenesis. We have identified that strains with mutations in cwf12 have inefficient splicing, mainly when the 5'SS differs from the consensus. However, although Δsaf5 cells also have some dependency on 5'SS sequence, we noticed that when one intron of a given pre-mRNA was affected, the rest of the introns of the same pre-mRNA had high probabilities of being also affected. This observation points Saf5 as a link between transcription rate and splicing.
Collapse
Affiliation(s)
- Sonia Borao
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, Barcelona, Spain
| | - Montserrat Vega
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, Barcelona, Spain
| | - Susanna Boronat
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, Barcelona, Spain
| | - Elena Hidalgo
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, Barcelona, Spain
| | - Stefan Hümmer
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, Barcelona, Spain
| | - José Ayté
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, Barcelona, Spain
| |
Collapse
|
3
|
Margasyuk S, Kalinina M, Petrova M, Skvortsov D, Cao C, Pervouchine DD. RNA in situ conformation sequencing reveals novel long-range RNA structures with impact on splicing. RNA (NEW YORK, N.Y.) 2023; 29:1423-1436. [PMID: 37295923 PMCID: PMC10573301 DOI: 10.1261/rna.079508.122] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 05/22/2023] [Indexed: 06/12/2023]
Abstract
Over recent years, long-range RNA structure has emerged as a factor that is fundamental to alternative splicing regulation. An increasing number of human disorders are now being associated with splicing defects; hence it is essential to develop methods that assess long-range RNA structure experimentally. RNA in situ conformation sequencing (RIC-seq) is a method that recapitulates RNA structure within physiological RNA-protein complexes. In this work, we juxtapose pairs of conserved complementary regions (PCCRs) that were predicted in silico with the results of RIC-seq experiments conducted in seven human cell lines. We show statistically that RIC-seq support of PCCRs correlates with their properties, such as equilibrium free energy, presence of compensatory substitutions, and occurrence of A-to-I RNA editing sites and forked eCLIP peaks. Exons enclosed in PCCRs that are supported by RIC-seq tend to have weaker splice sites and lower inclusion rates, which is indicative of post-transcriptional splicing regulation mediated by RNA structure. Based on these findings, we prioritize PCCRs according to their RIC-seq support and show, using antisense nucleotides and minigene mutagenesis, that PCCRs in two disease-associated human genes, PHF20L1 and CASK, and also PCCRs in their murine orthologs, impact alternative splicing. In sum, we demonstrate how RIC-seq experiments can be used to discover functional long-range RNA structures, and particularly those that regulate alternative splicing.
Collapse
Affiliation(s)
- Sergey Margasyuk
- Skolkovo Institute of Science and Technology, Moscow 143026, Russia
| | - Marina Kalinina
- Skolkovo Institute of Science and Technology, Moscow 143026, Russia
| | - Marina Petrova
- Skolkovo Institute of Science and Technology, Moscow 143026, Russia
| | - Dmitry Skvortsov
- Skolkovo Institute of Science and Technology, Moscow 143026, Russia
- Moscow State University, Faculty of Chemistry, Moscow 119991, Russia
| | - Changchang Cao
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | | |
Collapse
|
4
|
Lim WF, Rinaldi C. RNA Transcript Diversity in Neuromuscular Research. J Neuromuscul Dis 2023:JND221601. [PMID: 37182892 DOI: 10.3233/jnd-221601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Three decades since the Human Genome Project began, scientists have now identified more then 25,000 protein coding genes in the human genome. The vast majority of the protein coding genes (> 90%) are multi-exonic, with the coding DNA being interrupted by intronic sequences, which are removed from the pre-mRNA transcripts before being translated into proteins, a process called splicing maturation. Variations in this process, i.e. by exon skipping, intron retention, alternative 5' splice site (5'ss), 3' splice site (3'ss), or polyadenylation usage, lead to remarkable transcriptome and proteome diversity in human tissues. Given its critical biological importance, alternative splicing is tightly regulated in a tissue- and developmental stage-specific manner. The central nervous system and skeletal muscle are amongst the tissues with the highest number of differentially expressed alternative exons, revealing a remarkable degree of transcriptome complexity. It is therefore not surprising that splicing mis-regulation is causally associated with a myriad of neuromuscular diseases, including but not limited to amyotrophic lateral sclerosis (ALS), spinal muscular atrophy (SMA), Duchenne muscular dystrophy (DMD), and myotonic dystrophy type 1 and 2 (DM1, DM2). A gene's transcript diversity has since become an integral and an important consideration for drug design, development and therapy. In this review, we will discuss transcript diversity in the context of neuromuscular diseases and current approaches to address splicing mis-regulation.
Collapse
Affiliation(s)
- Wooi Fang Lim
- Department of Paediatrics and Institute of Developmental and Regenerative Medicine, University of Oxford, Oxford, UK
| | - Carlo Rinaldi
- Department of Paediatrics and Institute of Developmental and Regenerative Medicine, University of Oxford, Oxford, UK
- MDUK Oxford Neuromuscular Centre, University of Oxford, Oxford, UK
| |
Collapse
|
5
|
PARP1′s Involvement in RNA Polymerase II Elongation: Pausing and Releasing Regulation through the Integrator and Super Elongation Complex. Cells 2022; 11:cells11203202. [PMID: 36291070 PMCID: PMC9600911 DOI: 10.3390/cells11203202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 10/07/2022] [Accepted: 10/08/2022] [Indexed: 11/17/2022] Open
Abstract
RNA polymerase elongation along the gene body is tightly regulated to ensure proper transcription and alternative splicing events. Understanding the mechanism and factors critical in regulating the rate of RNA polymerase II elongation and processivity is clearly important. Recently we showed that PARP1, a well-known DNA repair protein, when bound to chromatin, regulates RNA polymerase II elongation. However, the mechanism by which it does so is not known. In the current study, we aimed to tease out how PARP1 regulates RNAPII elongation. We show, both in vivo and in vitro, that PARP1 binds directly to the Integrator subunit 3 (IntS3), a member of the elongation Integrator complex. The association between the two proteins is mediated via the C-terminal domain of PARP1 to the C-terminal domain of IntS3. Interestingly, the occupancy of IntS3 along two PARP1 target genes mimicked that of PARP1, suggesting a role in its recruitment/assembly of elongation factors. Indeed, the knockdown of PARP1 resulted in differential chromatin association and gene occupancy of IntS3 and other key elongation factors. Most of these PARP1-mediated effects were due to the physical presence of PARP1 rather than its PARylation activity. These studies argue that PARP1 controls the progressive RNAPII elongation complexes. In summary, we present a platform to begin to decipher PARP1′s role in recruiting/scaffolding elongation factors along the gene body regions during RNA polymerase II elongation and gene regulation.
Collapse
|
6
|
Zhang S, Mao M, Lv Y, Yang Y, He W, Song Y, Wang Y, Yang Y, Al Abo M, Freedman JA, Patierno SR, Wang Y, Wang Z. A widespread length-dependent splicing dysregulation in cancer. SCIENCE ADVANCES 2022; 8:eabn9232. [PMID: 35977015 PMCID: PMC9385142 DOI: 10.1126/sciadv.abn9232] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Accepted: 07/01/2022] [Indexed: 06/15/2023]
Abstract
Dysregulation of alternative splicing is a key molecular hallmark of cancer. However, the common features and underlying mechanisms remain unclear. Here, we report an intriguing length-dependent splicing regulation in cancers. By systematically analyzing the transcriptome of thousands of cancer patients, we found that short exons are more likely to be mis-spliced and preferentially excluded in cancers. Compared to other exons, cancer-associated short exons (CASEs) are more conserved and likely to encode in-frame low-complexity peptides, with functional enrichment in GTPase regulators and cell adhesion. We developed a CASE-based panel as reliable cancer stratification markers and strong predictors for survival, which is clinically useful because the detection of short exon splicing is practical. Mechanistically, mis-splicing of CASEs is regulated by elevated transcription and alteration of certain RNA binding proteins in cancers. Our findings uncover a common feature of cancer-specific splicing dysregulation with important clinical implications in cancer diagnosis and therapies.
Collapse
Affiliation(s)
- Sirui Zhang
- CAS Key Laboratory of Computational Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Miaowei Mao
- CAS Key Laboratory of Computational Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Yuesheng Lv
- Institute of Cancer Stem Cell, Dalian Medical University, Dalian 116044, China
| | - Yingqun Yang
- CAS Key Laboratory of Computational Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
- Shanghai Tech University, Shanghai 200031, China
| | - Weijing He
- Department of Colorectal Surgery, Fudan University Shanghai Cancer Center, Shanghai 200032, China
- Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Yongmei Song
- State Key Laboratory of Molecular Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, China
| | - Yongbo Wang
- Department of Cellular and Genetic Medicine, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China
| | - Yun Yang
- CAS Key Laboratory of Computational Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Muthana Al Abo
- Duke Cancer Institute, Duke University School of Medicine, Durham, NC 27710, USA
| | - Jennifer A. Freedman
- Duke Cancer Institute, Duke University School of Medicine, Durham, NC 27710, USA
- Division of Medical Oncology, Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA
| | - Steven R. Patierno
- Duke Cancer Institute, Duke University School of Medicine, Durham, NC 27710, USA
- Division of Medical Oncology, Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA
| | - Yang Wang
- Institute of Cancer Stem Cell, Dalian Medical University, Dalian 116044, China
| | - Zefeng Wang
- CAS Key Laboratory of Computational Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| |
Collapse
|
7
|
Kufel J, Diachenko N, Golisz A. Alternative splicing as a key player in the fine-tuning of the immunity response in Arabidopsis. MOLECULAR PLANT PATHOLOGY 2022; 23:1226-1238. [PMID: 35567423 PMCID: PMC9276941 DOI: 10.1111/mpp.13228] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 04/11/2022] [Accepted: 04/13/2022] [Indexed: 06/01/2023]
Abstract
Plants, like animals, are constantly exposed to abiotic and biotic stresses, which often inhibit plant growth and development, and cause tissue damage, disease, and even plant death. Efficient and timely response to stress requires appropriate co- and posttranscriptional reprogramming of gene expression. Alternative pre-mRNA splicing provides an important layer of this regulation by controlling the level of factors involved in stress response and generating additional protein isoforms with specific features. Recent high-throughput studies have revealed that several defence genes undergo alternative splicing that is often affected by pathogen infection. Despite extensive work, the exact mechanisms underlying these relationships are still unclear, but the contribution of alternative protein isoforms to the defence response and the role of regulatory factors, including components of the splicing machinery, have been established. Modulation of gene expression in response to stress includes alternative splicing, chromatin remodelling, histone modifications, and nucleosome occupancy. How these processes affect plant immunity is mostly unknown, but these facets open new regulatory possibilities. Here we provide an overview of the current state of knowledge and recent findings regarding the growing importance of alternative splicing in plant response to biotic stress.
Collapse
Affiliation(s)
- Joanna Kufel
- Institute of Genetics and BiotechnologyFaculty of BiologyUniversity of WarsawWarsawPoland
| | - Nataliia Diachenko
- Institute of Genetics and BiotechnologyFaculty of BiologyUniversity of WarsawWarsawPoland
| | - Anna Golisz
- Institute of Genetics and BiotechnologyFaculty of BiologyUniversity of WarsawWarsawPoland
| |
Collapse
|
8
|
Szaflarski W, Leśniczak-Staszak M, Sowiński M, Ojha S, Aulas A, Dave D, Malla S, Anderson P, Ivanov P, Lyons SM. Early rRNA processing is a stress-dependent regulatory event whose inhibition maintains nucleolar integrity. Nucleic Acids Res 2022; 50:1033-1051. [PMID: 34928368 PMCID: PMC8789083 DOI: 10.1093/nar/gkab1231] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 11/24/2021] [Accepted: 12/02/2021] [Indexed: 01/20/2023] Open
Abstract
The production of ribosomes is an energy-intensive process owing to the intricacy of these massive macromolecular machines. Each human ribosome contains 80 ribosomal proteins and four non-coding RNAs. Accurate assembly requires precise regulation of protein and RNA subunits. In response to stress, the integrated stress response (ISR) rapidly inhibits global translation. How rRNA is coordinately regulated with the rapid inhibition of ribosomal protein synthesis is not known. Here, we show that stress specifically inhibits the first step of rRNA processing. Unprocessed rRNA is stored within the nucleolus, and when stress resolves, it re-enters the ribosome biogenesis pathway. Retention of unprocessed rRNA within the nucleolus aids in the maintenance of this organelle. This response is independent of the ISR or inhibition of cellular translation but is independently regulated. Failure to coordinately control ribosomal protein translation and rRNA production results in nucleolar fragmentation. Our study unveils how the rapid translational shut-off in response to stress coordinates with rRNA synthesis production to maintain nucleolar integrity.
Collapse
Affiliation(s)
- Witold Szaflarski
- Department of Histology and Embryology, Poznan University of Medical Sciences, Poznań, Poland
| | - Marta Leśniczak-Staszak
- Department of Histology and Embryology, Poznan University of Medical Sciences, Poznań, Poland
| | - Mateusz Sowiński
- Department of Histology and Embryology, Poznan University of Medical Sciences, Poznań, Poland
| | - Sandeep Ojha
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, USA
- The Genome Science Institute, Boston University School of Medicine, Boston, MA, USA
| | - Anaïs Aulas
- Predictive Oncology Laboratory, Cancer Research Center of Marseille (CRCM), Inserm U1068, CNRS UMR7258, Institut Paoli-Calmettes, Aix Marseille Université, Marseille, France
| | - Dhwani Dave
- Division of Rheumatology, Inflammation and Immunity, Brigham and Women's Hospital, Boston, MA, USA
| | - Sulochan Malla
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, USA
- The Genome Science Institute, Boston University School of Medicine, Boston, MA, USA
| | - Paul Anderson
- Division of Rheumatology, Inflammation and Immunity, Brigham and Women's Hospital, Boston, MA, USA
- Department of Medicine, Harvard Medical School, Boston, MA, USA
| | - Pavel Ivanov
- Division of Rheumatology, Inflammation and Immunity, Brigham and Women's Hospital, Boston, MA, USA
- Department of Medicine, Harvard Medical School, Boston, MA, USA
| | - Shawn M Lyons
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, USA
- The Genome Science Institute, Boston University School of Medicine, Boston, MA, USA
| |
Collapse
|
9
|
Kumari A, Sedehizadeh S, Brook JD, Kozlowski P, Wojciechowska M. Differential fates of introns in gene expression due to global alternative splicing. Hum Genet 2022; 141:31-47. [PMID: 34907472 PMCID: PMC8758631 DOI: 10.1007/s00439-021-02409-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Accepted: 12/02/2021] [Indexed: 02/06/2023]
Abstract
The discovery of introns over four decades ago revealed a new vision of genes and their interrupted arrangement. Throughout the years, it has appeared that introns play essential roles in the regulation of gene expression. Unique processing of excised introns through the formation of lariats suggests a widespread role for these molecules in the structure and function of cells. In addition to rapid destruction, these lariats may linger on in the nucleus or may even be exported to the cytoplasm, where they remain stable circular RNAs (circRNAs). Alternative splicing (AS) is a source of diversity in mature transcripts harboring retained introns (RI-mRNAs). Such RNAs may contain one or more entire retained intron(s) (RIs), but they may also have intron fragments resulting from sequential excision of smaller subfragments via recursive splicing (RS), which is characteristic of long introns. There are many potential fates of RI-mRNAs, including their downregulation via nuclear and cytoplasmic surveillance systems and the generation of new protein isoforms with potentially different functions. Various reports have linked the presence of such unprocessed transcripts in mammals to important roles in normal development and in disease-related conditions. In certain human neurological-neuromuscular disorders, including myotonic dystrophy type 2 (DM2), frontotemporal dementia/amyotrophic lateral sclerosis (FTD/ALS) and Duchenne muscular dystrophy (DMD), peculiar processing of long introns has been identified and is associated with their pathogenic effects. In this review, we discuss different mechanisms involved in the processing of introns during AS and the functions of these large sections of the genome in our biology.
Collapse
Affiliation(s)
- Anjani Kumari
- Queen's Medical Centre, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
| | - Saam Sedehizadeh
- Queen's Medical Centre, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
| | - John David Brook
- Queen's Medical Centre, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
| | - Piotr Kozlowski
- Department of Molecular Genetics, Institute of Bioorganic Chemistry, Polish Academy of Sciences, 61-704, Poznan, Poland
| | - Marzena Wojciechowska
- Department of Molecular Genetics, Institute of Bioorganic Chemistry, Polish Academy of Sciences, 61-704, Poznan, Poland.
- Department of Rare Human Diseases, Institute of Bioorganic Chemistry, Polish Academy of Sciences, 61-704, Poznan, Poland.
| |
Collapse
|
10
|
Borao S, Ayté J, Hümmer S. Evolution of the Early Spliceosomal Complex-From Constitutive to Regulated Splicing. Int J Mol Sci 2021; 22:ijms222212444. [PMID: 34830325 PMCID: PMC8624252 DOI: 10.3390/ijms222212444] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 11/15/2021] [Accepted: 11/16/2021] [Indexed: 12/14/2022] Open
Abstract
Pre-mRNA splicing is a major process in the regulated expression of genes in eukaryotes, and alternative splicing is used to generate different proteins from the same coding gene. Splicing is a catalytic process that removes introns and ligates exons to create the RNA sequence that codifies the final protein. While this is achieved in an autocatalytic process in ancestral group II introns in prokaryotes, the spliceosome has evolved during eukaryogenesis to assist in this process and to finally provide the opportunity for intron-specific splicing. In the early stage of splicing, the RNA 5' and 3' splice sites must be brought within proximity to correctly assemble the active spliceosome and perform the excision and ligation reactions. The assembly of this first complex, termed E-complex, is currently the least understood process. We focused in this review on the formation of the E-complex and compared its composition and function in three different organisms. We highlight the common ancestral mechanisms in S. cerevisiae, S. pombe, and mammals and conclude with a unifying model for intron definition in constitutive and regulated co-transcriptional splicing.
Collapse
Affiliation(s)
- Sonia Borao
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, 08003 Barcelona, Spain;
| | - José Ayté
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, 08003 Barcelona, Spain;
- Correspondence: (J.A.); (S.H.)
| | - Stefan Hümmer
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, 08003 Barcelona, Spain;
- Translational Molecular Pathology, Vall d’Hebron Research Institute (VHIR), CIBERONC, 08035 Barcelona, Spain
- Correspondence: (J.A.); (S.H.)
| |
Collapse
|
11
|
Maudlin IE, Beggs JD. Conditional depletion of transcriptional kinases Ctk1 and Bur1 and effects on co-transcriptional spliceosome assembly and pre-mRNA splicing. RNA Biol 2021; 18:782-793. [PMID: 34705599 PMCID: PMC8782173 DOI: 10.1080/15476286.2021.1991673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 09/21/2021] [Indexed: 11/28/2022] Open
Abstract
From yeast to humans, pre-mRNA splicing occurs mainly co-transcriptionally, with splicing and transcription functionally coupled such that they influence one another. The recruitment model of co-transcriptional splicing proposes that core members of the transcription elongation machinery have the potential to influence co-transcriptional spliceosome assembly and pre-mRNA splicing. Here, we tested whether the transcription elongation kinases Bur1 and Ctk1 affect co-transcriptional spliceosome assembly and pre-mRNA splicing in the budding yeast Saccharomyces cerevisiae. In S. cerevisiae, Ctk1 is the major kinase that phosphorylates serine 2 of the carboxy-terminal domain of the largest subunit of RNA polymerase II, whilst Bur1 augments the kinase activity of Ctk1 and is the major kinase for elongation factor Spt5. We used the auxin-inducible degron system to conditionally deplete Bur1 and Ctk1 kinases, and investigated the effects on co-transcriptional spliceosome assembly and pre-mRNA splicing. Depletion of Ctk1 effectively reduced phosphorylation of serine 2 of the carboxy-terminal domain but did not impact co-transcriptional spliceosome assembly or pre-mRNA splicing. In striking contrast, depletion of Bur1 did not reduce phosphorylation of serine 2 of the carboxy-terminal domain, but reduced Spt5 phosphorylation and enhanced co-transcriptional spliceosome assembly and pre-mRNA splicing, suggesting a role for this kinase in modulating co-transcriptional splicing.
Collapse
Affiliation(s)
- Isabella E. Maudlin
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - Jean D. Beggs
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| |
Collapse
|
12
|
Naro C, Bielli P, Sette C. Oncogenic dysregulation of pre-mRNA processing by protein kinases: challenges and therapeutic opportunities. FEBS J 2021; 288:6250-6272. [PMID: 34092037 PMCID: PMC8596628 DOI: 10.1111/febs.16057] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 05/13/2021] [Accepted: 06/04/2021] [Indexed: 12/12/2022]
Abstract
Alternative splicing and polyadenylation represent two major steps in pre-mRNA-processing, which ensure proper gene expression and diversification of human transcriptomes. Deregulation of these processes contributes to oncogenic programmes involved in the onset, progression and evolution of human cancers, which often result in the acquisition of resistance to existing therapies. On the other hand, cancer cells frequently increase their transcriptional rate and develop a transcriptional addiction, which imposes a high stress on the pre-mRNA-processing machinery and establishes a therapeutically exploitable vulnerability. A prominent role in fine-tuning pre-mRNA-processing mechanisms is played by three main families of protein kinases: serine arginine protein kinase (SRPK), CDC-like kinase (CLK) and cyclin-dependent kinase (CDK). These kinases phosphorylate the RNA polymerase, splicing factors and regulatory proteins involved in cleavage and polyadenylation of the nascent transcripts. The activity of SRPKs, CLKs and CDKs can be altered in cancer cells, and their inhibition was shown to exert anticancer effects. In this review, we describe key findings that have been reported on these topics and discuss challenges and opportunities of developing therapeutic approaches targeting splicing factor kinases.
Collapse
Affiliation(s)
- Chiara Naro
- Department of NeuroscienceSection of Human AnatomyCatholic University of the Sacred HeartRomeItaly
- Fondazione Policlinico Universitario A. GemelliIRCCSRomeItaly
| | - Pamela Bielli
- Department of Biomedicine and PreventionUniversity of Rome Tor VergataItaly
- Fondazione Santa LuciaIRCCSRomeItaly
| | - Claudio Sette
- Department of NeuroscienceSection of Human AnatomyCatholic University of the Sacred HeartRomeItaly
- Fondazione Santa LuciaIRCCSRomeItaly
| |
Collapse
|
13
|
Differential Incidence of Tongue Base Cancer in Male and Female HPV16-Transgenic Mice: Role of Female Sex Hormone Receptors. Pathogens 2021; 10:pathogens10101224. [PMID: 34684173 PMCID: PMC8539196 DOI: 10.3390/pathogens10101224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 09/05/2021] [Accepted: 09/07/2021] [Indexed: 11/16/2022] Open
Abstract
A growing proportion of oropharyngeal squamous cell carcinomas (OPSCC) are associated with infection by high-risk human papillomavirus (HPV). For reasons that remain largely unknown, HPV+OPSCC is significantly more common in men than in women. This study aims to determine the incidence of OPSCC in male and female HPV16-transgenic mice and to explore the role of female sex hormone receptors in the sexual predisposition for HPV+ OPSCC. The tongues of 30-weeks-old HPV16-transgenic male (n = 80) and female (n = 90) and matched wild-type male (n = 10) and female (n = 10) FVB/n mice were screened histologically for intraepithelial and invasive lesions in 2017 at the Centre for the Research and Technology of Agro-Environmental and Biological Sciences (CITAB), Portugal. Expression of estrogen receptors alpha (ERα) and beta (ERβ), progesterone receptors (PR) and matrix metalloproteinase 2 (MMP2) was studied immunohistochemically. Collagen remodeling was studied using picrosirius red. Female mice showed robust ERα and ERβ expression in intraepithelial and invasive lesions, which was accompanied by strong MMP2 expression and marked collagen remodeling. Male mice showed minimal ERα, ERβ and MMP2 expression and unaltered collagen patterns. These results confirm the association of HPV16 with tongue base cancer in both sexes. The higher cancer incidence in female versus male mice contrasts with data from OPSCC patients and is associated with enhanced ER expression via MMP2 upregulation.
Collapse
|
14
|
Willbanks A, Wood S, Cheng JX. RNA Epigenetics: Fine-Tuning Chromatin Plasticity and Transcriptional Regulation, and the Implications in Human Diseases. Genes (Basel) 2021; 12:genes12050627. [PMID: 33922187 PMCID: PMC8145807 DOI: 10.3390/genes12050627] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 04/13/2021] [Accepted: 04/14/2021] [Indexed: 02/08/2023] Open
Abstract
Chromatin structure plays an essential role in eukaryotic gene expression and cell identity. Traditionally, DNA and histone modifications have been the focus of chromatin regulation; however, recent molecular and imaging studies have revealed an intimate connection between RNA epigenetics and chromatin structure. Accumulating evidence suggests that RNA serves as the interplay between chromatin and the transcription and splicing machineries within the cell. Additionally, epigenetic modifications of nascent RNAs fine-tune these interactions to regulate gene expression at the co- and post-transcriptional levels in normal cell development and human diseases. This review will provide an overview of recent advances in the emerging field of RNA epigenetics, specifically the role of RNA modifications and RNA modifying proteins in chromatin remodeling, transcription activation and RNA processing, as well as translational implications in human diseases.
Collapse
|
15
|
A machine learning-based framework for modeling transcription elongation. Proc Natl Acad Sci U S A 2021; 118:2007450118. [PMID: 33526657 DOI: 10.1073/pnas.2007450118] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
RNA polymerase II (Pol II) generally pauses at certain positions along gene bodies, thereby interrupting the transcription elongation process, which is often coupled with various important biological functions, such as precursor mRNA splicing and gene expression regulation. Characterizing the transcriptional elongation dynamics can thus help us understand many essential biological processes in eukaryotic cells. However, experimentally measuring Pol II elongation rates is generally time and resource consuming. We developed PEPMAN (polymerase II elongation pausing modeling through attention-based deep neural network), a deep learning-based model that accurately predicts Pol II pausing sites based on the native elongating transcript sequencing (NET-seq) data. Through fully taking advantage of the attention mechanism, PEPMAN is able to decipher important sequence features underlying Pol II pausing. More importantly, we demonstrated that the analyses of the PEPMAN-predicted results around various types of alternative splicing sites can provide useful clues into understanding the cotranscriptional splicing events. In addition, associating the PEPMAN prediction results with different epigenetic features can help reveal important factors related to the transcription elongation process. All these results demonstrated that PEPMAN can provide a useful and effective tool for modeling transcription elongation and understanding the related biological factors from available high-throughput sequencing data.
Collapse
|
16
|
Fang S, Hou X, Qiu K, He R, Feng X, Liang X. The occurrence and function of alternative splicing in fungi. FUNGAL BIOL REV 2020. [DOI: 10.1016/j.fbr.2020.10.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
17
|
Kajitani N, Schwartz S. Role of Viral Ribonucleoproteins in Human Papillomavirus Type 16 Gene Expression. Viruses 2020; 12:E1110. [PMID: 33007936 PMCID: PMC7600041 DOI: 10.3390/v12101110] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2020] [Revised: 09/25/2020] [Accepted: 09/26/2020] [Indexed: 02/06/2023] Open
Abstract
Human papillomaviruses (HPVs) depend on the cellular RNA-processing machineries including alternative RNA splicing and polyadenylation to coordinate HPV gene expression. HPV RNA processing is controlled by cis-regulatory RNA elements and trans-regulatory factors since the HPV splice sites are suboptimal. The definition of HPV exons and introns may differ between individual HPV mRNA species and is complicated by the fact that many HPV protein-coding sequences overlap. The formation of HPV ribonucleoproteins consisting of HPV pre-mRNAs and multiple cellular RNA-binding proteins may result in the different outcomes of HPV gene expression, which contributes to the HPV life cycle progression and HPV-associated cancer development. In this review, we summarize the regulation of HPV16 gene expression at the level of RNA processing with focus on the interactions between HPV16 pre-mRNAs and cellular RNA-binding factors.
Collapse
Affiliation(s)
- Naoko Kajitani
- Department of Laboratory Medicine, Lund University, 22184 Lund, Sweden;
| | | |
Collapse
|
18
|
Shao W, Ding Z, Zheng ZZ, Shen JJ, Shen YX, Pu J, Fan YJ, Query CC, Xu YZ. Prp5-Spt8/Spt3 interaction mediates a reciprocal coupling between splicing and transcription. Nucleic Acids Res 2020; 48:5799-5813. [PMID: 32399566 PMCID: PMC7293005 DOI: 10.1093/nar/gkaa311] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 04/08/2020] [Accepted: 05/03/2020] [Indexed: 01/23/2023] Open
Abstract
Transcription and pre-mRNA splicing are coupled to promote gene expression and regulation. However, mechanisms by which transcription and splicing influence each other are still under investigation. The ATPase Prp5p is required for pre-spliceosome assembly and splicing proofreading at the branch-point region. From an open UV mutagenesis screen for genetic suppressors of prp5 defects and subsequent targeted testing, we identify components of the TBP-binding module of the Spt–Ada–Gcn5 Acetyltransferase (SAGA) complex, Spt8p and Spt3p. Spt8Δ and spt3Δ rescue the cold-sensitivity of prp5-GAR allele, and prp5 mutants restore growth of spt8Δ and spt3Δ strains on 6-azauracil. By chromatin immunoprecipitation (ChIP), we find that prp5 alleles decrease recruitment of RNA polymerase II (Pol II) to an intron-containing gene, which is rescued by spt8Δ. Further ChIP-seq reveals that global effects on Pol II-binding are mutually rescued by prp5-GAR and spt8Δ. Inhibited splicing caused by prp5-GAR is also restored by spt8Δ. In vitro assays indicate that Prp5p directly interacts with Spt8p, but not Spt3p. We demonstrate that Prp5p's splicing proofreading is modulated by Spt8p and Spt3p. Therefore, this study reveals that interactions between the TBP-binding module of SAGA and the spliceosomal ATPase Prp5p mediate a balance between transcription initiation/elongation and pre-spliceosome assembly.
Collapse
Affiliation(s)
- Wei Shao
- School of Basic Medical Sciences, Anhui Medical University, Hefei, Anhui 230032, China.,State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, College of Life Science, Wuhan University, Wuhan, Hubei 430072, China
| | - Zhan Ding
- State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, College of Life Science, Wuhan University, Wuhan, Hubei 430072, China.,Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Zeng-Zhang Zheng
- Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Ji-Jia Shen
- School of Basic Medical Sciences, Anhui Medical University, Hefei, Anhui 230032, China
| | - Yu-Xian Shen
- School of Basic Medical Sciences, Anhui Medical University, Hefei, Anhui 230032, China
| | - Jia Pu
- Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Yu-Jie Fan
- State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, College of Life Science, Wuhan University, Wuhan, Hubei 430072, China
| | - Charles C Query
- Department of Cell Biology, Albert Einstein College of Medicine, NY 10461, USA
| | - Yong-Zhen Xu
- State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, College of Life Science, Wuhan University, Wuhan, Hubei 430072, China
| |
Collapse
|
19
|
Aslanzadeh V, Beggs JD. Revisiting the window of opportunity for cotranscriptional splicing in budding yeast. RNA (NEW YORK, N.Y.) 2020; 26:1081-1085. [PMID: 32439718 PMCID: PMC7430680 DOI: 10.1261/rna.075895.120] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We reported previously that, in budding yeast, transcription rate affects both the efficiency and fidelity of pre-mRNA splicing, especially of ribosomal protein transcripts. Here, we report that the majority of ribosomal protein transcripts with non-consensus 5' splice sites are spliced less efficiently when transcription is faster, and more efficiently with slower transcription. These results support the "window of opportunity" model, and we suggest a possible mechanism to explain these findings.
Collapse
Affiliation(s)
- Vahid Aslanzadeh
- Wellcome Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
| | - Jean D Beggs
- Wellcome Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
| |
Collapse
|
20
|
Tellier M, Maudlin I, Murphy S. Transcription and splicing: A two-way street. WILEY INTERDISCIPLINARY REVIEWS. RNA 2020; 11:e1593. [PMID: 32128990 DOI: 10.1002/wrna.1593] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 12/18/2019] [Accepted: 02/12/2020] [Indexed: 12/11/2022]
Abstract
RNA synthesis by RNA polymerase II and RNA processing are closely coupled during the transcription cycle of protein-coding genes. This coupling affords opportunities for quality control and regulation of gene expression and the effects can go in both directions. For example, polymerase speed can affect splice site selection and splicing can increase transcription and affect the chromatin landscape. Here we review the many ways that transcription and splicing influence one another, including how splicing "talks back" to transcription. We will also place the connections between transcription and splicing in the context of other RNA processing events that define the exons that will make up the final mRNA. This article is categorized under: RNA Processing > Splicing Mechanisms RNA Processing > Splicing Regulation/Alternative Splicing.
Collapse
Affiliation(s)
- Michael Tellier
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Isabella Maudlin
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Shona Murphy
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| |
Collapse
|
21
|
Tang SJ, Shen H, An O, Hong H, Li J, Song Y, Han J, Tay DJT, Ng VHE, Bellido Molias F, Leong KW, Pitcheshwar P, Yang H, Chen L. Cis- and trans-regulations of pre-mRNA splicing by RNA editing enzymes influence cancer development. Nat Commun 2020; 11:799. [PMID: 32034135 PMCID: PMC7005744 DOI: 10.1038/s41467-020-14621-5] [Citation(s) in RCA: 65] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Accepted: 01/16/2020] [Indexed: 12/18/2022] Open
Abstract
RNA editing and splicing are the two major processes that dynamically regulate human transcriptome diversity. Despite growing evidence of crosstalk between RNA editing enzymes (mainly ADAR1) and splicing machineries, detailed mechanistic explanations and their biological importance in diseases, such as cancer are still lacking. Herein, we identify approximately a hundred high-confidence splicing events altered by ADAR1 and/or ADAR2, and ADAR1 or ADAR2 protein can regulate cassette exons in both directions. We unravel a binding tendency of ADARs to dsRNAs that involves GA-rich sequences for editing and splicing regulation. ADAR1 edits an intronic splicing silencer, leading to recruitment of SRSF7 and repression of exon inclusion. We also present a mechanism through which ADAR2 binds to dsRNA formed between GA-rich sequences and polypyrimidine (Py)-tract and precludes access of U2AF65 to 3' splice site. Furthermore, we find these ADARs-regulated splicing changes per se influence tumorigenesis, not merely byproducts of ADARs editing and binding.
Collapse
Affiliation(s)
- Sze Jing Tang
- Cancer Science Institute of Singapore, National University of Singapore, Singapore, 117599, Singapore
| | - Haoqing Shen
- Cancer Science Institute of Singapore, National University of Singapore, Singapore, 117599, Singapore
- Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117594, Singapore
| | - Omer An
- Cancer Science Institute of Singapore, National University of Singapore, Singapore, 117599, Singapore
| | - HuiQi Hong
- Cancer Science Institute of Singapore, National University of Singapore, Singapore, 117599, Singapore
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117549, Singapore
| | - Jia Li
- Cancer Science Institute of Singapore, National University of Singapore, Singapore, 117599, Singapore
| | - Yangyang Song
- Cancer Science Institute of Singapore, National University of Singapore, Singapore, 117599, Singapore
| | - Jian Han
- Cancer Science Institute of Singapore, National University of Singapore, Singapore, 117599, Singapore
| | - Daryl Jin Tai Tay
- Cancer Science Institute of Singapore, National University of Singapore, Singapore, 117599, Singapore
| | - Vanessa Hui En Ng
- Cancer Science Institute of Singapore, National University of Singapore, Singapore, 117599, Singapore
| | - Fernando Bellido Molias
- Cancer Science Institute of Singapore, National University of Singapore, Singapore, 117599, Singapore
| | - Ka Wai Leong
- Cancer Science Institute of Singapore, National University of Singapore, Singapore, 117599, Singapore
| | - Priyankaa Pitcheshwar
- Cancer Science Institute of Singapore, National University of Singapore, Singapore, 117599, Singapore
- Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117594, Singapore
| | - Henry Yang
- Cancer Science Institute of Singapore, National University of Singapore, Singapore, 117599, Singapore
| | - Leilei Chen
- Cancer Science Institute of Singapore, National University of Singapore, Singapore, 117599, Singapore.
- Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117594, Singapore.
| |
Collapse
|
22
|
Taylor J, Lee SC. Mutations in spliceosome genes and therapeutic opportunities in myeloid malignancies. Genes Chromosomes Cancer 2019; 58:889-902. [PMID: 31334570 PMCID: PMC6852509 DOI: 10.1002/gcc.22784] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Accepted: 07/17/2019] [Indexed: 12/21/2022] Open
Abstract
Since the discovery of RNA splicing more than 40 years ago, our comprehension of the molecular events orchestrating constitutive and alternative splicing has greatly improved. Dysregulation of pre-mRNA splicing has been observed in many human diseases including neurodegenerative diseases and cancer. The recent identification of frequent somatic mutations in core components of the spliceosome in myeloid malignancies and functional analysis using model systems has advanced our knowledge of how splicing alterations contribute to disease pathogenesis. In this review, we summarize our current understanding on the mechanisms of how mutant splicing factors impact splicing and the resulting functional and pathophysiological consequences. We also review recent advances to develop novel therapeutic approaches targeting splicing catalysis and splicing regulatory proteins, and discuss emerging technologies using oligonucleotide-based therapies to modulate pathogenically spliced isoforms.
Collapse
Affiliation(s)
- Justin Taylor
- Human Oncology and Pathogenesis ProgramMemorial Sloan Kettering Cancer CenterNew YorkNew York
- Leukemia Service, Department of MedicineMemorial Sloan Kettering Cancer CenterNew YorkNew York
| | - Stanley C. Lee
- Human Oncology and Pathogenesis ProgramMemorial Sloan Kettering Cancer CenterNew YorkNew York
| |
Collapse
|
23
|
Control of RNA Pol II Speed by PNUTS-PP1 and Spt5 Dephosphorylation Facilitates Termination by a "Sitting Duck Torpedo" Mechanism. Mol Cell 2019; 76:896-908.e4. [PMID: 31677974 DOI: 10.1016/j.molcel.2019.09.031] [Citation(s) in RCA: 119] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 08/14/2019] [Accepted: 09/24/2019] [Indexed: 12/11/2022]
Abstract
Control of transcription speed, which influences many co-transcriptional processes, is poorly understood. We report that PNUTS-PP1 phosphatase is a negative regulator of RNA polymerase II (Pol II) elongation rate. The PNUTS W401A mutation, which disrupts PP1 binding, causes genome-wide acceleration of transcription associated with hyper-phosphorylation of the Spt5 elongation factor. Immediately downstream of poly(A) sites, Pol II decelerates from >2 kb/min to <1 kb/min, which correlates with Spt5 dephosphorylation. Pol II deceleration and Spt5 dephosphorylation require poly(A) site recognition and the PNUTS-PP1 complex, which is in turn necessary for transcription termination. These results lead to a model for termination, the "sitting duck torpedo" mechanism, where poly(A) site-dependent deceleration caused by PNUTS-PP1 and Spt5 dephosphorylation is required to convert Pol II into a viable target for the Xrn2 terminator exonuclease. Spt5 and its bacterial homolog NusG therefore have related functions controlling kinetic competition between RNA polymerases and the termination factors that pursue them.
Collapse
|
24
|
Zatreanu D, Han Z, Mitter R, Tumini E, Williams H, Gregersen L, Dirac-Svejstrup AB, Roma S, Stewart A, Aguilera A, Svejstrup JQ. Elongation Factor TFIIS Prevents Transcription Stress and R-Loop Accumulation to Maintain Genome Stability. Mol Cell 2019; 76:57-69.e9. [PMID: 31519522 PMCID: PMC6863433 DOI: 10.1016/j.molcel.2019.07.037] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 05/28/2019] [Accepted: 07/26/2019] [Indexed: 01/08/2023]
Abstract
Although correlations between RNA polymerase II (RNAPII) transcription stress, R-loops, and genome instability have been established, the mechanisms underlying these connections remain poorly understood. Here, we used a mutant version of the transcription elongation factor TFIIS (TFIISmut), aiming to specifically induce increased levels of RNAPII pausing, arrest, and/or backtracking in human cells. Indeed, TFIISmut expression results in slower elongation rates, relative depletion of polymerases from the end of genes, and increased levels of stopped RNAPII; it affects mRNA splicing and termination as well. Remarkably, TFIISmut expression also dramatically increases R-loops, which may form at the anterior end of backtracked RNAPII and trigger genome instability, including DNA strand breaks. These results shed light on the relationship between transcription stress and R-loops and suggest that different classes of R-loops may exist, potentially with distinct consequences for genome stability.
Collapse
Affiliation(s)
- Diana Zatreanu
- Mechanisms of Transcription Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Zhong Han
- Mechanisms of Transcription Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Richard Mitter
- Bioinformatics and Biostatistics Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Emanuela Tumini
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Consejo Superior de Investigaciones Científicas-Universidad Pablo de Olavide-Universidad de Sevilla, Seville, Spain
| | - Hannah Williams
- Mechanisms of Transcription Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Lea Gregersen
- Mechanisms of Transcription Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - A Barbara Dirac-Svejstrup
- Mechanisms of Transcription Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Stefania Roma
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Consejo Superior de Investigaciones Científicas-Universidad Pablo de Olavide-Universidad de Sevilla, Seville, Spain
| | - Aengus Stewart
- Bioinformatics and Biostatistics Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Andres Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Consejo Superior de Investigaciones Científicas-Universidad Pablo de Olavide-Universidad de Sevilla, Seville, Spain
| | - Jesper Q Svejstrup
- Mechanisms of Transcription Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK.
| |
Collapse
|
25
|
Maudlin IE, Beggs JD. Spt5 modulates cotranscriptional spliceosome assembly in Saccharomyces cerevisiae. RNA (NEW YORK, N.Y.) 2019; 25:1298-1310. [PMID: 31289129 PMCID: PMC6800482 DOI: 10.1261/rna.070425.119] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 05/29/2019] [Indexed: 06/09/2023]
Abstract
There is increasing evidence from yeast to humans that pre-mRNA splicing occurs mainly cotranscriptionally, such that splicing and transcription are functionally coupled. Currently, there is little insight into the contribution of the core transcription elongation machinery to cotranscriptional spliceosome assembly and pre-mRNA splicing. Spt5 is a member of the core transcription elongation machinery and an essential protein, whose absence in budding yeast causes defects in pre-mRNA splicing. To determine how Spt5 affects pre-mRNA splicing, we used the auxin-inducible degron system to conditionally deplete Spt5 in Saccharomyces cerevisiae and assayed effects on cotranscriptional spliceosome assembly and splicing. We show that Spt5 is needed for efficient splicing and for the accumulation of U5 snRNPs at intron-containing genes, and therefore for stable cotranscriptional assembly of spliceosomes. The defect in cotranscriptional spliceosome assembly can explain the relatively mild splicing defect as being a consequence of the failure of cotranscriptional splicing. Coimmunoprecipitation of Spt5 with core spliceosomal proteins and all spliceosomal snRNAs suggests a model whereby Spt5 promotes cotranscriptional pre-mRNA splicing by stabilizing the association of U5 snRNP with spliceosome complexes as they assemble on the nascent transcript. If this phenomenon is conserved in higher eukaryotes, it has the potential to be important for cotranscriptional regulation of alternative splicing.
Collapse
Affiliation(s)
- Isabella E Maudlin
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
| | - Jean D Beggs
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
| |
Collapse
|
26
|
Singh NN, Singh RN. How RNA structure dictates the usage of a critical exon of spinal muscular atrophy gene. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2019; 1862:194403. [PMID: 31323435 DOI: 10.1016/j.bbagrm.2019.07.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Accepted: 07/09/2019] [Indexed: 12/17/2022]
Abstract
Role of RNA structure in pre-mRNA splicing has been implicated for several critical exons associated with genetic disorders. However, much of the structural studies linked to pre-mRNA splicing regulation are limited to terminal stem-loop structures (hairpins) sequestering splice sites. In few instances, role of long-distance interactions is implicated as the major determinant of splicing regulation. With the recent surge of reports of circular RNA (circRNAs) generated by backsplicing, role of Alu-associated RNA structures formed by long-range interactions are taking central stage. Humans contain two nearly identical copies of Survival Motor Neuron (SMN) genes, SMN1 and SMN2. Deletion or mutation of SMN1 coupled with the inability of SMN2 to compensate for the loss of SMN1 due to exon 7 skipping causes spinal muscular atrophy (SMA), one of the leading genetic diseases of children. In this review, we describe how structural elements formed by both local and long-distance interactions are being exploited to modulate SMN2 exon 7 splicing as a potential therapy for SMA. We also discuss how Alu-associated secondary structure modulates generation of a vast repertoire of SMN circRNAs. This article is part of a Special Issue entitled: RNA structure and splicing regulation edited by Francisco Baralle, Ravindra Singh and Stefan Stamm.
Collapse
Affiliation(s)
- Natalia N Singh
- Department of Biomedical Science, Iowa State University, Ames, IA 50011, United States of America
| | - Ravindra N Singh
- Department of Biomedical Science, Iowa State University, Ames, IA 50011, United States of America.
| |
Collapse
|
27
|
Peck SA, Hughes KD, Victorino JF, Mosley AL. Writing a wrong: Coupled RNA polymerase II transcription and RNA quality control. WILEY INTERDISCIPLINARY REVIEWS-RNA 2019; 10:e1529. [PMID: 30848101 PMCID: PMC6570551 DOI: 10.1002/wrna.1529] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 12/27/2018] [Accepted: 02/07/2019] [Indexed: 12/20/2022]
Abstract
Processing and maturation of precursor RNA species is coupled to RNA polymerase II transcription. Co-transcriptional RNA processing helps to ensure efficient and proper capping, splicing, and 3' end processing of different RNA species to help ensure quality control of the transcriptome. Many improperly processed transcripts are not exported from the nucleus, are restricted to the site of transcription, and are in some cases degraded, which helps to limit any possibility of aberrant RNA causing harm to cellular health. These critical quality control pathways are regulated by the highly dynamic protein-protein interaction network at the site of transcription. Recent work has further revealed the extent to which the processes of transcription and RNA processing and quality control are integrated, and how critically their coupling relies upon the dynamic protein interactions that take place co-transcriptionally. This review focuses specifically on the intricate balance between 3' end processing and RNA decay during transcription termination. This article is categorized under: RNA Turnover and Surveillance > Turnover/Surveillance Mechanisms RNA Processing > 3' End Processing RNA Processing > Splicing Mechanisms RNA Processing > Capping and 5' End Modifications.
Collapse
Affiliation(s)
- Sarah A Peck
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Katlyn D Hughes
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Jose F Victorino
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Amber L Mosley
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana
| |
Collapse
|
28
|
Matveeva EA, Al-Tinawi QMH, Rouchka EC, Fondufe-Mittendorf YN. Coupling of PARP1-mediated chromatin structural changes to transcriptional RNA polymerase II elongation and cotranscriptional splicing. Epigenetics Chromatin 2019; 12:15. [PMID: 30777121 PMCID: PMC6378753 DOI: 10.1186/s13072-019-0261-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 02/12/2019] [Indexed: 01/02/2023] Open
Abstract
Background Recently, we showed that PARP1 is involved in cotranscriptional splicing, possibly by bridging chromatin to RNA and recruiting splicing factors. It also can influence alternative splicing decisions through the regulation of RNAPII elongation. In this study, we investigated the effect of PARP1-mediated chromatin changes on RNAPII movement, during transcription and alternative splicing. Results We show that RNAPII pauses at PARP1–chromatin structures within the gene body. Knockdown of PARP1 abolishes this RNAPII pausing, suggesting that PARP1 may regulate RNAPII elongation. Additionally, PARP1 alters nucleosome deposition and histone post-translational modifications at specific exon–intron boundaries, thereby affecting RNAPII movement. Lastly, genome-wide analyses confirmed that PARP1 influences changes in RNAPII elongation by either reducing or increasing the rate of RNAPII elongation depending on the chromatin context. Conclusions These studies suggest a context-specific effect of PARP1–chromatin binding on RNA polymerase movement and provide a platform to delineate PARP1’s role in RNA biogenesis and processing. Electronic supplementary material The online version of this article (10.1186/s13072-019-0261-1) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Elena A Matveeva
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY, 40536, USA
| | - Qamar M H Al-Tinawi
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY, 40536, USA.,Alfaisal University, Al Maather' Riyadh, 12714, Saudi Arabia
| | - Eric C Rouchka
- Kentucky Biomedical Research Infrastructure Network Bioinformatics Core, 522 East Gray Street, Louisville, KY, 40292, USA.,Department of Computer Engineering and Computer Science, University of Louisville, Louisville, KY, 40292, USA
| | | |
Collapse
|
29
|
Lai Y, Cuzick A, Lu XM, Wang J, Katiyar N, Tsuchiya T, Le Roch K, McDowell JM, Holub E, Eulgem T. The Arabidopsis RRM domain protein EDM3 mediates race-specific disease resistance by controlling H3K9me2-dependent alternative polyadenylation of RPP7 immune receptor transcripts. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2019; 97:646-660. [PMID: 30407670 PMCID: PMC7138032 DOI: 10.1111/tpj.14148] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 09/27/2018] [Accepted: 10/26/2018] [Indexed: 05/18/2023]
Abstract
The NLR-receptor RPP7 mediates race-specific immunity in Arabidopsis. Previous screens for enhanced downy mildew (edm) mutants identified the co-chaperone SGT1b (EDM1) and the PHD-finger protein EDM2 as critical regulators of RPP7. Here, we describe a third edm mutant compromised in RPP7 immunity, edm3. EDM3 encodes a nuclear-localized protein featuring an RNA-recognition motif. Like EDM2, EDM3 promotes histone H3 lysine 9 dimethylation (H3K9me2) at RPP7. Global profiling of H3K9me2 showed EDM3 to affect this silencing mark at a large set of loci. Importantly, both EDM3 and EDM2 co-associate in vivo with H3K9me2-marked chromatin and transcripts at a critical proximal polyadenylation site of RPP7, where they suppress proximal transcript polyadeylation/termination. Our results highlight the complexity of plant NLR gene regulation, and establish a functional and physical link between a histone mark and NLR-transcript processing.
Collapse
Affiliation(s)
- Yan Lai
- Department of Botany and Plant Sciences, Center for Plant Cell Biology, Institute of Integrative Genome Biology, University of California at Riverside, Riverside, CA, 92521, USA
- College of Life Sciences, Fujian Agricultural and Forestry University, Fuzhou, Fujian, 350002, China
| | - Alayne Cuzick
- School of Life Sciences, University of Warwick, Wellesbourne Campus, Warwick, CV35 9EF, UK
- Biointeractions and Crop Protection, Rothamsted Research, Harpenden, AL5 2JQ, UK
| | - Xueqing M Lu
- Department of Molecular, Cell and Systems Biology, Center for Infectious Disease and Vector Research, Institute of Integrative Genome Biology, University of California at Riverside, Riverside, CA, 92521, USA
| | - Jianqiang Wang
- Department of Botany and Plant Sciences, Center for Plant Cell Biology, Institute of Integrative Genome Biology, University of California at Riverside, Riverside, CA, 92521, USA
| | - Neerja Katiyar
- Institute of Integrative Genome Biology, University of California at Riverside, Riverside, CA, 92521, USA
| | - Tokuji Tsuchiya
- College of Bioresource Sciences, Nihon University, Kanagawa, 252-0880, Japan
| | - Karine Le Roch
- Department of Molecular, Cell and Systems Biology, Center for Infectious Disease and Vector Research, Institute of Integrative Genome Biology, University of California at Riverside, Riverside, CA, 92521, USA
| | - John M McDowell
- Department of Plant Pathology, Physiology, and Weed Science, Virginia Tech, Blacksburg, VA, 24060-0329, USA
| | - Eric Holub
- School of Life Sciences, University of Warwick, Wellesbourne Campus, Warwick, CV35 9EF, UK
| | - Thomas Eulgem
- Department of Botany and Plant Sciences, Center for Plant Cell Biology, Institute of Integrative Genome Biology, University of California at Riverside, Riverside, CA, 92521, USA
| |
Collapse
|
30
|
Zhang XO, Fu Y, Mou H, Xue W, Weng Z. The temporal landscape of recursive splicing during Pol II transcription elongation in human cells. PLoS Genet 2018; 14:e1007579. [PMID: 30148885 PMCID: PMC6110456 DOI: 10.1371/journal.pgen.1007579] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Accepted: 07/20/2018] [Indexed: 01/28/2023] Open
Abstract
Recursive splicing (RS) is an evolutionarily conserved process of removing long introns via multiple steps of splicing. It was first discovered in Drosophila and recently proven to occur also in humans. The detailed mechanism of recursive splicing is not well understood, in particular, whether it is kinetically coupled with transcription. To investigate the dynamic process that underlies recursive splicing, we systematically characterized 342 RS sites in three human cell types using published time-series data that monitored synchronized Pol II elongation and nascent RNA production with 4-thiouridine labeling. We found that half of the RS events occurred post-transcriptionally with long delays. For at least 18-47% RS introns, we detected RS junction reads only after detecting canonical splicing junction reads, supporting the notion that these introns were removed by both recursive splicing and canonical splicing. Furthermore, the choice of which splicing mechanism was used showed cell type specificity. Our results suggest that recursive splicing supplements, rather than replaces, canonical splicing for removing long introns.
Collapse
Affiliation(s)
- Xiao-Ou Zhang
- Program in Bioinformatics and Integrative Biology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Yu Fu
- Program in Bioinformatics and Integrative Biology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- Bioinformatics Program, Boston University, Boston, Massachusetts, United States of America
| | - Haiwei Mou
- RNA Therapeutics Institute, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Wen Xue
- RNA Therapeutics Institute, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Zhiping Weng
- Program in Bioinformatics and Integrative Biology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| |
Collapse
|
31
|
Nejat N, Ramalingam A, Mantri N. Advances in Transcriptomics of Plants. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2018; 164:161-185. [PMID: 29392354 DOI: 10.1007/10_2017_52] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The current global population of 7.3 billion is estimated to reach 9.7 billion in the year 2050. Rapid population growth is driving up global food demand. Additionally, global climate change, environmental degradation, drought, emerging diseases, and salty soils are the current threats to global food security. In order to mitigate the adverse effects of these diverse agricultural productivity constraints and enhance crop yield and stress-tolerance in plants, we need to go beyond traditional and molecular plant breeding. The powerful new tools for genome editing, Transcription Activator-Like Effector Nucleases (TALENs) and Clustered Regulatory Interspaced Short Palindromic Repeats (CRISPR)/Cas systems (CRISPR-Cas9), have been hailed as a quantum leap forward in the development of stress-resistant plants. Plant breeding techniques, however, have several drawbacks. Hence, identification of transcriptional regulatory elements and deciphering mechanisms underlying transcriptional regulation are crucial to avoiding unintended consequences in modified crop plants, which could ultimately have negative impacts on human health. RNA splicing as an essential regulated post-transcriptional process, alternative polyadenylation as an RNA-processing mechanism, along with non-coding RNAs (microRNAs, small interfering RNAs and long non-coding RNAs) have been identified as major players in gene regulation. In this chapter, we highlight new findings on the essential roles of alternative splicing and alternative polyadenylation in plant development and response to biotic and abiotic stresses. We also discuss biogenesis and the functions of microRNAs (miRNAs) and small interfering RNAs (siRNAs) in plants and recent advances in our knowledge of the roles of miRNAs and siRNAs in plant stress response. Graphical Abstract.
Collapse
Affiliation(s)
- Naghmeh Nejat
- The Pangenomics Group, School of Science, RMIT University, Melbourne, VIC, Australia
| | - Abirami Ramalingam
- The Pangenomics Group, School of Science, RMIT University, Melbourne, VIC, Australia
| | - Nitin Mantri
- The Pangenomics Group, School of Science, RMIT University, Melbourne, VIC, Australia.
| |
Collapse
|
32
|
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.
Collapse
|
33
|
Graham SV. Keratinocyte Differentiation-Dependent Human Papillomavirus Gene Regulation. Viruses 2017; 9:E245. [PMID: 28867768 PMCID: PMC5618011 DOI: 10.3390/v9090245] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 08/24/2017] [Accepted: 08/25/2017] [Indexed: 12/29/2022] Open
Abstract
Human papillomaviruses (HPVs) cause diseases ranging from benign warts to invasive cancers. HPVs infect epithelial cells and their replication cycle is tightly linked with the differentiation process of the infected keratinocyte. The normal replication cycle involves an early and a late phase. The early phase encompasses viral entry and initial genome replication, stimulation of cell division and inhibition of apoptosis in the infected cell. Late events in the HPV life cycle include viral genome amplification, virion formation, and release into the environment from the surface of the epithelium. The main proteins required at the late stage of infection for viral genome amplification include E1, E2, E4 and E5. The late proteins L1 and L2 are structural proteins that form the viral capsid. Regulation of these late events involves both cellular and viral proteins. The late viral mRNAs are expressed from a specific late promoter but final late mRNA levels in the infected cell are controlled by splicing, polyadenylation, nuclear export and RNA stability. Viral late protein expression is also controlled at the level of translation. This review will discuss current knowledge of how HPV late gene expression is regulated.
Collapse
Affiliation(s)
- Sheila V Graham
- MRC-University of Glasgow Centre for Virus Research, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Garscube Estate, Glasgow G61 1QH, UK.
| |
Collapse
|
34
|
Balestra D, Scalet D, Pagani F, Rogalska ME, Mari R, Bernardi F, Pinotti M. An Exon-Specific U1snRNA Induces a Robust Factor IX Activity in Mice Expressing Multiple Human FIX Splicing Mutants. MOLECULAR THERAPY-NUCLEIC ACIDS 2016; 5:e370. [PMID: 27701399 PMCID: PMC5095682 DOI: 10.1038/mtna.2016.77] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Accepted: 07/21/2016] [Indexed: 12/30/2022]
Abstract
In cellular models we have demonstrated that a unique U1snRNA targeting an intronic region downstream of a defective exon (Exon-specific U1snRNA, ExSpeU1) can rescue multiple exon-skipping mutations, a relevant cause of genetic disease. Here, we explored in mice the ExSpeU1 U1fix9 toward two model Hemophilia B-causing mutations at the 5′ (c.519A > G) or 3′ (c.392-8T > G) splice sites of F9 exon 5. Hydrodynamic injection of wt-BALB/C mice with plasmids expressing the wt and mutant (hFIX-2G5′ss and hFIX-8G3′ss) splicing-competent human factor IX (hFIX) cassettes resulted in the expression of hFIX transcripts lacking exon 5 in liver, and in low plasma levels of inactive hFIX. Coinjection of U1fix9, but not of U1wt, restored exon inclusion of variants and in the intrinsically weak FIXwt context. This resulted in appreciable circulating hFIX levels (mean ± SD; hFIX-2G5′ss, 1.0 ± 0.5 µg/ml; hFIX-8G3′ss, 1.2 ± 0.3 µg/ml; and hFIXwt, 1.9 ± 0.6 µg/ml), leading to a striking shortening (from ~100 seconds of untreated mice to ~80 seconds) of FIX-dependent coagulation times, indicating a hFIX with normal specific activity. This is the first proof-of-concept in vivo that a unique ExSpeU1 can efficiently rescue gene expression impaired by distinct exon-skipping variants, which extends the applicability of ExSpeU1s to panels of mutations and thus cohort of patients.
Collapse
Affiliation(s)
- Dario Balestra
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - Daniela Scalet
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - Franco Pagani
- Internation Centre for Genetic Engineering and Biotechnology, Trieste, Italy
| | | | - Rosella Mari
- Haemostasis & Thrombosis Center, University of Ferrara, Ferrara, Italy
| | - Francesco Bernardi
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy.,LTTA Center, University of Ferrara, Ferrara, Italy
| | - Mirko Pinotti
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy.,LTTA Center, University of Ferrara, Ferrara, Italy
| |
Collapse
|
35
|
Jimeno-González S, Reyes JC. Chromatin structure and pre-mRNA processing work together. Transcription 2016; 7:63-8. [PMID: 27028548 PMCID: PMC4984687 DOI: 10.1080/21541264.2016.1168507] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Revised: 03/14/2016] [Accepted: 03/14/2016] [Indexed: 10/22/2022] Open
Abstract
Chromatin is the natural context for transcription elongation. However, the elongating RNA polymerase II (RNAPII) is forced to pause by the positioned nucleosomes present in gene bodies. Here, we briefly discuss the current results suggesting that those pauses could serve as a mechanism to coordinate transcription elongation with pre-mRNA processing. Further, histone post-translational modifications have been found to regulate the recruitment of factors involved in pre-mRNA processing. This view highlights the important regulatory role of the chromatin context in the whole process of the mature mRNA synthesis.
Collapse
Affiliation(s)
- Silvia Jimeno-González
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Consejo Superior de Investigaciones Científicas (CSIC), Seville, Spain
| | - José C. Reyes
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Consejo Superior de Investigaciones Científicas (CSIC), Seville, Spain
| |
Collapse
|
36
|
Juan-Mateu J, Villate O, Eizirik DL. MECHANISMS IN ENDOCRINOLOGY: Alternative splicing: the new frontier in diabetes research. Eur J Endocrinol 2016; 174:R225-38. [PMID: 26628584 PMCID: PMC5331159 DOI: 10.1530/eje-15-0916] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 12/01/2015] [Indexed: 12/30/2022]
Abstract
Type 1 diabetes (T1D) is a chronic autoimmune disease in which pancreatic β cells are killed by infiltrating immune cells and by cytokines released by these cells. This takes place in the context of a dysregulated dialogue between invading immune cells and target β cells, but the intracellular signals that decide β cell fate remain to be clarified. Alternative splicing (AS) is a complex post-transcriptional regulatory mechanism affecting gene expression. It regulates the inclusion/exclusion of exons into mature mRNAs, allowing individual genes to produce multiple protein isoforms that expand the proteome diversity. Functionally related transcript populations are co-ordinately spliced by master splicing factors, defining regulatory networks that allow cells to rapidly adapt their transcriptome in response to intra and extracellular cues. There is a growing interest in the role of AS in autoimmune diseases, but little is known regarding its role in T1D. In this review, we discuss recent findings suggesting that splicing events occurring in both immune and pancreatic β cells contribute to the pathogenesis of T1D. Splicing switches in T cells and in lymph node stromal cells are involved in the modulation of the immune response against β cells, while β cells exposed to pro-inflammatory cytokines activate complex splicing networks that modulate β cell viability, expression of neoantigens and susceptibility to immune-induced stress. Unveiling the role of AS in β cell functional loss and death will increase our understanding of T1D pathogenesis and may open new avenues for disease prevention and therapy.
Collapse
Affiliation(s)
- Jonàs Juan-Mateu
- Medical FacultyULB Center for Diabetes Research and Welbio, Université Libre de Bruxelles (ULB), Route de Lennik, 808 - CP618, B-1070 Brussels, Belgium
| | - Olatz Villate
- Medical FacultyULB Center for Diabetes Research and Welbio, Université Libre de Bruxelles (ULB), Route de Lennik, 808 - CP618, B-1070 Brussels, Belgium
| | - Décio L Eizirik
- Medical FacultyULB Center for Diabetes Research and Welbio, Université Libre de Bruxelles (ULB), Route de Lennik, 808 - CP618, B-1070 Brussels, Belgium
| |
Collapse
|
37
|
Saldi T, Cortazar MA, Sheridan RM, Bentley DL. Coupling of RNA Polymerase II Transcription Elongation with Pre-mRNA Splicing. J Mol Biol 2016; 428:2623-2635. [PMID: 27107644 DOI: 10.1016/j.jmb.2016.04.017] [Citation(s) in RCA: 176] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Revised: 03/27/2016] [Accepted: 04/12/2016] [Indexed: 01/07/2023]
Abstract
Pre-mRNA maturation frequently occurs at the same time and place as transcription by RNA polymerase II. The co-transcriptionality of mRNA processing has permitted the evolution of mechanisms that functionally couple transcription elongation with diverse events that occur on the nascent RNA. This review summarizes the current understanding of the relationship between transcriptional elongation through a chromatin template and co-transcriptional splicing including alternative splicing decisions that affect the expression of most human genes.
Collapse
Affiliation(s)
- Tassa Saldi
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, P.O. Box 6511, Aurora, CO 80045, USA
| | - Michael A Cortazar
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, P.O. Box 6511, Aurora, CO 80045, USA
| | - Ryan M Sheridan
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, P.O. Box 6511, Aurora, CO 80045, USA
| | - David L Bentley
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, P.O. Box 6511, Aurora, CO 80045, USA.
| |
Collapse
|
38
|
Davie JR, Xu W, Delcuve GP. Histone H3K4 trimethylation: dynamic interplay with pre-mRNA splicing. Biochem Cell Biol 2016; 94:1-11. [DOI: 10.1139/bcb-2015-0065] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Histone H3 lysine 4 trimethylation (H3K4me3) is often stated as a mark of transcriptionally active promoters. However, closer study of the positioning of H3K4me3 shows the mark locating primarily after the first exon at the 5′ splice site and overlapping with a CpG island in mammalian cells. There are several enzyme complexes that are involved in the placement of the H3K4me3 mark, including multiple protein complexes containing SETD1A, SETD1B, and MLL1 enzymes (writers). CXXC1, which is associated with SETD1A and SETD1B, target these enzymes to unmethylated CpG islands. Lysine demethylases (KDM5 family members, erasers) demethylate H3K4me3. The H3K4me3 mark is recognized by several proteins (readers), including lysine acetyltransferase complexes, chromatin remodelers, and RNA bound proteins involved in pre-mRNA splicing. Interestingly, attenuation of H3K4me3 impacts pre-mRNA splicing, and inhibition of pre-mRNA splicing attenuates H3K4me3.
Collapse
Affiliation(s)
- James R. Davie
- Children’s Hospital Research Institute of Manitoba, University of Manitoba, Winnipeg, MB R3E 3P4, Canada
- Children’s Hospital Research Institute of Manitoba, University of Manitoba, Winnipeg, MB R3E 3P4, Canada
| | - Wayne Xu
- Children’s Hospital Research Institute of Manitoba, University of Manitoba, Winnipeg, MB R3E 3P4, Canada
- Children’s Hospital Research Institute of Manitoba, University of Manitoba, Winnipeg, MB R3E 3P4, Canada
| | - Genevieve P. Delcuve
- Children’s Hospital Research Institute of Manitoba, University of Manitoba, Winnipeg, MB R3E 3P4, Canada
- Children’s Hospital Research Institute of Manitoba, University of Manitoba, Winnipeg, MB R3E 3P4, Canada
| |
Collapse
|
39
|
Vilborg A, Passarelli MC, Steitz JA. Calcium signaling and transcription: elongation, DoGs, and eRNAs. ACTA ACUST UNITED AC 2016; 3. [PMID: 29147672 DOI: 10.14800/rci.1169] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The calcium ion (Ca2+) is a key intracellular signaling molecule with far-reaching effects on many cellular processes. One of the most important such Ca2+ regulated processes is transcription. A body of literature describes the effect of Ca2+ signaling on transcription initiation as occurring mainly through activation of gene-specific transcription factors by Ca2+-induced signaling cascades. However, the reach of Ca2+ extends far beyond the first step of transcription. In fact, Ca2+ can regulate all phases of transcription, with additional effects on transcription-associated events such as alternative splicing. Importantly, Ca2+ signaling mediates reduced transcription termination in response to certain stress conditions. This reduction allows readthrough transcription, generating a highly inducible and diverse class of downstream of gene containing transcripts (DoGs) that we have recently described.
Collapse
Affiliation(s)
- Anna Vilborg
- Department of Molecular Biophysics and Biochemistry, Howard Hughes Medical Institute Boyer Center for Molecular Medicine, Yale University School of Medicine, 295 Congress Avenue, New Haven, CT 06536, USA
| | - Maria C Passarelli
- Department of Molecular Biophysics and Biochemistry, Howard Hughes Medical Institute Boyer Center for Molecular Medicine, Yale University School of Medicine, 295 Congress Avenue, New Haven, CT 06536, USA
| | - Joan A Steitz
- Department of Molecular Biophysics and Biochemistry, Howard Hughes Medical Institute Boyer Center for Molecular Medicine, Yale University School of Medicine, 295 Congress Avenue, New Haven, CT 06536, USA
| |
Collapse
|
40
|
Daguenet E, Dujardin G, Valcárcel J. The pathogenicity of splicing defects: mechanistic insights into pre-mRNA processing inform novel therapeutic approaches. EMBO Rep 2015; 16:1640-55. [PMID: 26566663 DOI: 10.15252/embr.201541116] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 10/12/2015] [Indexed: 12/22/2022] Open
Abstract
Removal of introns from pre-mRNA precursors (pre-mRNA splicing) is a necessary step for the expression of most genes in multicellular organisms, and alternative patterns of intron removal diversify and regulate the output of genomic information. Mutation or natural variation in pre-mRNA sequences, as well as in spliceosomal components and regulatory factors, has been implicated in the etiology and progression of numerous pathologies. These range from monogenic to multifactorial genetic diseases, including metabolic syndromes, muscular dystrophies, neurodegenerative and cardiovascular diseases, and cancer. Understanding the molecular mechanisms associated with splicing-related pathologies can provide key insights into the normal function and physiological context of the complex splicing machinery and establish sound basis for novel therapeutic approaches.
Collapse
Affiliation(s)
- Elisabeth Daguenet
- Centre de Regulació Genòmica (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain Universitat Pompeu-Fabra, Barcelona, Spain
| | - Gwendal Dujardin
- Centre de Regulació Genòmica (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain Universitat Pompeu-Fabra, Barcelona, Spain
| | - Juan Valcárcel
- Centre de Regulació Genòmica (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain Universitat Pompeu-Fabra, Barcelona, Spain Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
| |
Collapse
|
41
|
Native elongating transcript sequencing reveals human transcriptional activity at nucleotide resolution. Cell 2015; 161:541-554. [PMID: 25910208 DOI: 10.1016/j.cell.2015.03.010] [Citation(s) in RCA: 255] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Revised: 11/26/2014] [Accepted: 02/18/2015] [Indexed: 01/12/2023]
Abstract
Major features of transcription by human RNA polymerase II (Pol II) remain poorly defined due to a lack of quantitative approaches for visualizing Pol II progress at nucleotide resolution. We developed a simple and powerful approach for performing native elongating transcript sequencing (NET-seq) in human cells that globally maps strand-specific Pol II density at nucleotide resolution. NET-seq exposes a mode of antisense transcription that originates downstream and converges on transcription from the canonical promoter. Convergent transcription is associated with a distinctive chromatin configuration and is characteristic of lower-expressed genes. Integration of NET-seq with genomic footprinting data reveals stereotypic Pol II pausing coincident with transcription factor occupancy. Finally, exons retained in mature transcripts display Pol II pausing signatures that differ markedly from skipped exons, indicating an intrinsic capacity for Pol II to recognize exons with different processing fates. Together, human NET-seq exposes the topography and regulatory complexity of human gene expression.
Collapse
|
42
|
Tejedor JR, Tilgner H, Iannone C, Guigó R, Valcárcel J. Role of six single nucleotide polymorphisms, risk factors in coronary disease, in OLR1 alternative splicing. RNA (NEW YORK, N.Y.) 2015; 21:1187-1202. [PMID: 25904137 PMCID: PMC4436670 DOI: 10.1261/rna.049890.115] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Accepted: 03/12/2015] [Indexed: 06/04/2023]
Abstract
The OLR1 gene encodes the oxidized low-density lipoprotein receptor (LOX-1), which is responsible for the cellular uptake of oxidized LDL (Ox-LDL), foam cell formation in atheroma plaques and atherosclerotic plaque rupture. Alternative splicing (AS) of OLR1 exon 5 generates two protein isoforms with antagonistic functions in Ox-LDL uptake. Previous work identified six single nucleotide polymorphisms (SNPs) in linkage disequilibrium that influence the inclusion levels of OLR1 exon 5 and correlate with the risk of cardiovascular disease. Here we use minigenes to recapitulate the effects of two allelic series (Low- and High-Risk) on OLR1 AS and identify one SNP in intron 4 (rs3736234) as the main contributor to the differences in exon 5 inclusion, while the other SNPs in the allelic series attenuate the drastic effects of this key SNP. Bioinformatic, proteomic, mutational and functional high-throughput analyses allowed us to define regulatory sequence motifs and identify SR protein family members (SRSF1, SRSF2) and HMGA1 as factors involved in the regulation of OLR1 AS. Our results suggest that antagonism between SRSF1 and SRSF2/HMGA1, and differential recognition of their regulatory motifs depending on the identity of the rs3736234 polymorphism, influence OLR1 exon 5 inclusion and the efficiency of Ox-LDL uptake, with potential implications for atherosclerosis and coronary disease.
Collapse
Affiliation(s)
- J Ramón Tejedor
- Centre de Regulació Genòmica, 08003 Barcelona, Spain Universitat Pompeu Fabra, 08003 Barcelona, Spain
| | - Hagen Tilgner
- Centre de Regulació Genòmica, 08003 Barcelona, Spain Universitat Pompeu Fabra, 08003 Barcelona, Spain
| | - Camilla Iannone
- Centre de Regulació Genòmica, 08003 Barcelona, Spain Universitat Pompeu Fabra, 08003 Barcelona, Spain
| | - Roderic Guigó
- Centre de Regulació Genòmica, 08003 Barcelona, Spain Universitat Pompeu Fabra, 08003 Barcelona, Spain
| | - Juan Valcárcel
- Centre de Regulació Genòmica, 08003 Barcelona, Spain Universitat Pompeu Fabra, 08003 Barcelona, Spain Institució Catalana de Recerca i Estudis Avançats, 08020 Barcelona, Spain
| |
Collapse
|
43
|
Comprehensive transcriptome analysis using synthetic long-read sequencing reveals molecular co-association of distant splicing events. Nat Biotechnol 2015; 33:736-42. [PMID: 25985263 DOI: 10.1038/nbt.3242] [Citation(s) in RCA: 136] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Accepted: 04/21/2015] [Indexed: 01/02/2023]
Abstract
Alternative splicing shapes mammalian transcriptomes, with many RNA molecules undergoing multiple distant alternative splicing events. Comprehensive transcriptome analysis, including analysis of exon co-association in the same molecule, requires deep, long-read sequencing. Here we introduce an RNA sequencing method, synthetic long-read RNA sequencing (SLR-RNA-seq), in which small pools (≤1,000 molecules/pool, ≤1 molecule/gene for most genes) of full-length cDNAs are amplified, fragmented and short-read-sequenced. We demonstrate that these RNA sequences reconstructed from the short reads from each of the pools are mostly close to full length and contain few insertion and deletion errors. We report many previously undescribed isoforms (human brain: ∼13,800 affected genes, 14.5% of molecules; mouse brain ∼8,600 genes, 18% of molecules) and up to 165 human distant molecularly associated exon pairs (dMAPs) and distant molecularly and mutually exclusive pairs (dMEPs). Of 16 associated pairs detected in the mouse brain, 9 are conserved in human. Our results indicate conserved mechanisms that can produce distant but phased features on transcript and proteome isoforms.
Collapse
|
44
|
Kfir N, Lev-Maor G, Glaich O, Alajem A, Datta A, Sze S, Meshorer E, Ast G. SF3B1 Association with Chromatin Determines Splicing Outcomes. Cell Rep 2015; 11:618-29. [DOI: 10.1016/j.celrep.2015.03.048] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2014] [Revised: 02/25/2015] [Accepted: 03/22/2015] [Indexed: 01/08/2023] Open
|
45
|
Abstract
Precursor messenger RNA (pre-mRNA) splicing is a critical step in the posttranscriptional regulation of gene expression, providing significant expansion of the functional proteome of eukaryotic organisms with limited gene numbers. Split eukaryotic genes contain intervening sequences or introns disrupting protein-coding exons, and intron removal occurs by repeated assembly of a large and highly dynamic ribonucleoprotein complex termed the spliceosome, which is composed of five small nuclear ribonucleoprotein particles, U1, U2, U4/U6, and U5. Biochemical studies over the past 10 years have allowed the isolation as well as compositional, functional, and structural analysis of splicing complexes at distinct stages along the spliceosome cycle. The average human gene contains eight exons and seven introns, producing an average of three or more alternatively spliced mRNA isoforms. Recent high-throughput sequencing studies indicate that 100% of human genes produce at least two alternative mRNA isoforms. Mechanisms of alternative splicing include RNA-protein interactions of splicing factors with regulatory sites termed silencers or enhancers, RNA-RNA base-pairing interactions, or chromatin-based effects that can change or determine splicing patterns. Disease-causing mutations can often occur in splice sites near intron borders or in exonic or intronic RNA regulatory silencer or enhancer elements, as well as in genes that encode splicing factors. Together, these studies provide mechanistic insights into how spliceosome assembly, dynamics, and catalysis occur; how alternative splicing is regulated and evolves; and how splicing can be disrupted by cis- and trans-acting mutations leading to disease states. These findings make the spliceosome an attractive new target for small-molecule, antisense, and genome-editing therapeutic interventions.
Collapse
Affiliation(s)
- Yeon Lee
- Center for RNA Systems Biology; Division of Biochemistry, Biophysics, and Structural Biology; Department of Molecular and Cell Biology, University of California, Berkeley, California 94720-3204;
| | | |
Collapse
|
46
|
Arias MA, Lubkin A, Chasin LA. Splicing of designer exons informs a biophysical model for exon definition. RNA (NEW YORK, N.Y.) 2015; 21:213-229. [PMID: 25492963 PMCID: PMC4338349 DOI: 10.1261/rna.048009.114] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/06/2014] [Accepted: 10/29/2014] [Indexed: 06/04/2023]
Abstract
Pre-mRNA molecules in humans contain mostly short internal exons flanked by longer introns. To explain the removal of such introns, exon recognition instead of intron recognition has been proposed. We studied this exon definition using designer exons (DEs) made up of three prototype modules of our own design: an exonic splicing enhancer (ESE), an exonic splicing silencer (ESS), and a Reference Sequence (R) predicted to be neither. Each DE was examined as the central exon in a three-exon minigene. DEs made of R modules showed a sharp size dependence, with exons shorter than 14 nt and longer than 174 nt splicing poorly. Changing the strengths of the splice sites improved longer exon splicing but worsened shorter exon splicing, effectively displacing the curve to the right. For the ESE we found, unexpectedly, that its enhancement efficiency was independent of its position within the exon. For the ESS we found a step-wise positional increase in its effects; it was most effective at the 3' end of the exon. To apply these results quantitatively, we developed a biophysical model for exon definition of internal exons undergoing cotranscriptional splicing. This model features commitment to inclusion before the downstream exon is synthesized and competition between skipping and inclusion fates afterward. Collision of both exon ends to form an exon definition complex was incorporated to account for the effect of size; ESE/ESS effects were modeled on the basis of stabilization/destabilization. This model accurately predicted the outcome of independent experiments on more complex DEs that combined ESEs and ESSs.
Collapse
Affiliation(s)
- Mauricio A Arias
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
| | - Ashira Lubkin
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
| | - Lawrence A Chasin
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
| |
Collapse
|
47
|
de Klerk E, 't Hoen PAC. Alternative mRNA transcription, processing, and translation: insights from RNA sequencing. Trends Genet 2015; 31:128-39. [PMID: 25648499 DOI: 10.1016/j.tig.2015.01.001] [Citation(s) in RCA: 226] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2014] [Revised: 12/22/2014] [Accepted: 01/05/2015] [Indexed: 12/13/2022]
Abstract
The human transcriptome comprises >80,000 protein-coding transcripts and the estimated number of proteins synthesized from these transcripts is in the range of 250,000 to 1 million. These transcripts and proteins are encoded by less than 20,000 genes, suggesting extensive regulation at the transcriptional, post-transcriptional, and translational level. Here we review how RNA sequencing (RNA-seq) technologies have increased our understanding of the mechanisms that give rise to alternative transcripts and their alternative translation. We highlight four different regulatory processes: alternative transcription initiation, alternative splicing, alternative polyadenylation, and alternative translation initiation. We discuss their transcriptome-wide distribution, their impact on protein expression, their biological relevance, and the possible molecular mechanisms leading to their alternative regulation. We conclude with a discussion of the coordination and the interdependence of these four regulatory layers.
Collapse
Affiliation(s)
- Eleonora de Klerk
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Peter A C 't Hoen
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands.
| |
Collapse
|
48
|
Fong N, Kim H, Zhou Y, Ji X, Qiu J, Saldi T, Diener K, Jones K, Fu XD, Bentley DL. Pre-mRNA splicing is facilitated by an optimal RNA polymerase II elongation rate. Genes Dev 2015; 28:2663-76. [PMID: 25452276 PMCID: PMC4248296 DOI: 10.1101/gad.252106.114] [Citation(s) in RCA: 195] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Fong et al. examined cotranscriptional pre-mRNA splicing using RNA polymerase II mutants that change average elongation rates genome-wide. Slow and fast elongation affected constitutive and alternative splicing and often both increased or both decreased inclusion of a particular exon or retained intron. These results suggest that an optimal rate of transcriptional elongation is required for normal cotranscriptional pre-mRNA splicing. Alternative splicing modulates expression of most human genes. The kinetic model of cotranscriptional splicing suggests that slow elongation expands and that fast elongation compresses the “window of opportunity” for recognition of upstream splice sites, thereby increasing or decreasing inclusion of alternative exons. We tested the model using RNA polymerase II mutants that change average elongation rates genome-wide. Slow and fast elongation affected constitutive and alternative splicing, frequently altering exon inclusion and intron retention in ways not predicted by the model. Cassette exons included by slow and excluded by fast elongation (type I) have weaker splice sites, shorter flanking introns, and distinct sequence motifs relative to “slow-excluded” and “fast-included” exons (type II). Many rate-sensitive exons are misspliced in tumors. Unexpectedly, slow and fast elongation often both increased or both decreased inclusion of a particular exon or retained intron. These results suggest that an optimal rate of transcriptional elongation is required for normal cotranscriptional pre-mRNA splicing.
Collapse
Affiliation(s)
- Nova Fong
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, Colorado 80045, USA
| | - Hyunmin Kim
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, Colorado 80045, USA
| | - Yu Zhou
- Department of Cellular and Molecular Medicine, Institute of Genomic Medicine, University of California at San Diego, San Diego, California 92093, USA
| | - Xiong Ji
- Department of Cellular and Molecular Medicine, Institute of Genomic Medicine, University of California at San Diego, San Diego, California 92093, USA
| | - Jinsong Qiu
- Department of Cellular and Molecular Medicine, Institute of Genomic Medicine, University of California at San Diego, San Diego, California 92093, USA
| | - Tassa Saldi
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, Colorado 80045, USA
| | - Katrina Diener
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, Colorado 80045, USA
| | - Ken Jones
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, Colorado 80045, USA
| | - Xiang-Dong Fu
- Department of Cellular and Molecular Medicine, Institute of Genomic Medicine, University of California at San Diego, San Diego, California 92093, USA
| | - David L Bentley
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, Colorado 80045, USA;
| |
Collapse
|
49
|
Mauger O, Klinck R, Chabot B, Muchardt C, Allemand E, Batsché E. Alternative splicing regulates the expression of G9A and SUV39H2 methyltransferases, and dramatically changes SUV39H2 functions. Nucleic Acids Res 2015; 43:1869-82. [PMID: 25605796 PMCID: PMC4330376 DOI: 10.1093/nar/gkv013] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Alternative splicing is the main source of proteome diversity. Here, we have investigated how alternative splicing affects the function of two human histone methyltransferases (HMTase): G9A and SUV39H2. We show that exon 10 in G9A and exon 3 in SUV39H2 are alternatively included in a variety of tissues and cell lines, as well as in a different species. The production of these variants is likely tightly regulated because both constitutive and alternative splicing factors control their splicing profiles. Based on this evidence, we have assessed the link between the inclusion of these exons and the activity of both enzymes. We document that these HMTase genes yield several protein isoforms, which are likely issued from alternative splicing regulation. We demonstrate that inclusion of SUV39H2 exon 3 is a determinant of the stability, the sub-nuclear localization, and the HMTase activity. Genome-wide expression analysis further revealed that alternative inclusion of SUV39H2 exon 3 differentially modulates the expression of target genes. Our data also suggest that a variant of G9A may display a function that is independent of H3K9 methylation. Our work emphasizes that expression and function of genes are not collinear; therefore alternative splicing must be taken into account in any functional study.
Collapse
Affiliation(s)
- Oriane Mauger
- Sorbonne Universités, Université Pierre et Marie Curie, Université Paris 6, IFD, 4 Place Jussieu, 75252 PARIS cedex 05, France Institut Pasteur, Département de Biologie du Développement et Cellules Souches, CNRS URA2578, Unité de Régulation Epigénétique, 25 rue du Docteur Roux, Paris, 75015, France
| | - Roscoe Klinck
- Laboratory of Functional Genomics of the Université de Sherbrooke, Sherbrooke, Québec, J1E 4K8, Canada
| | - Benoit Chabot
- Laboratory of Functional Genomics of the Université de Sherbrooke, Sherbrooke, Québec, J1E 4K8, Canada Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke. Québec, J1E 4K8, Canada
| | - Christian Muchardt
- Institut Pasteur, Département de Biologie du Développement et Cellules Souches, CNRS URA2578, Unité de Régulation Epigénétique, 25 rue du Docteur Roux, Paris, 75015, France
| | - Eric Allemand
- Institut Pasteur, Département de Biologie du Développement et Cellules Souches, CNRS URA2578, Unité de Régulation Epigénétique, 25 rue du Docteur Roux, Paris, 75015, France
| | - Eric Batsché
- Institut Pasteur, Département de Biologie du Développement et Cellules Souches, CNRS URA2578, Unité de Régulation Epigénétique, 25 rue du Docteur Roux, Paris, 75015, France
| |
Collapse
|
50
|
Tejedor J, Papasaikas P, Valcárcel J. Genome-Wide Identification of Fas/CD95 Alternative Splicing Regulators Reveals Links with Iron Homeostasis. Mol Cell 2015; 57:23-38. [DOI: 10.1016/j.molcel.2014.10.029] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 09/24/2014] [Accepted: 10/31/2014] [Indexed: 10/24/2022]
|