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Fanara S, Schloesser M, Joris M, De Franco S, Vandevenne M, Kerff F, Hanikenne M, Motte P. The Arabidopsis SR45 splicing factor bridges the splicing machinery and the exon-exon junction complex. JOURNAL OF EXPERIMENTAL BOTANY 2024; 75:2280-2298. [PMID: 38180875 DOI: 10.1093/jxb/erae002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Accepted: 01/04/2024] [Indexed: 01/07/2024]
Abstract
The Arabidopsis splicing factor serine/arginine-rich 45 (SR45) contributes to several biological processes. The sr45-1 loss-of-function mutant exhibits delayed root development, late flowering, unusual numbers of floral organs, shorter siliques with decreased seed sets, narrower leaves and petals, and altered metal distribution. SR45 bears a unique RNA recognition motif (RRM) flanked by one serine/arginine-rich (RS) domain on both sides. Here, we studied the function of each SR45 domains by examining their involvement in: (i) the spatial distribution of SR45; (ii) the establishment of a protein-protein interaction network including spliceosomal and exon-exon junction complex (EJC) components; and (iii) the RNA binding specificity. We report that the endogenous SR45 promoter is active during vegetative and reproductive growth, and that the SR45 protein localizes in the nucleus. We demonstrate that the C-terminal arginine/serine-rich domain is a determinant of nuclear localization. We show that the SR45 RRM domain specifically binds purine-rich RNA motifs via three residues (H101, H141, and Y143), and is also involved in protein-protein interactions. We further show that SR45 bridges both mRNA splicing and surveillance machineries as a partner of EJC core components and peripheral factors, which requires phosphoresidues probably phosphorylated by kinases from both the CLK and SRPK families. Our findings provide insights into the contribution of each SR45 domain to both spliceosome and EJC assemblies.
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Affiliation(s)
- Steven Fanara
- InBioS-PhytoSystems, Functional Genomics and Plant Molecular Imaging, University of Liège, 4000, Liège, Belgium
| | - Marie Schloesser
- InBioS-PhytoSystems, Functional Genomics and Plant Molecular Imaging, University of Liège, 4000, Liège, Belgium
| | - Marine Joris
- InBioS-PhytoSystems, Functional Genomics and Plant Molecular Imaging, University of Liège, 4000, Liège, Belgium
| | - Simona De Franco
- InBioS-Center for Protein Engineering, Laboratory of Biological Macromolecules, University of Liège, 4000, Liège, Belgium
| | - Marylène Vandevenne
- InBioS-Center for Protein Engineering, Laboratory of Biological Macromolecules, University of Liège, 4000, Liège, Belgium
| | - Frédéric Kerff
- InBioS-Center for Protein Engineering, Laboratory of Crystallography, University of Liège, 4000, Liège, Belgium
| | - Marc Hanikenne
- InBioS-PhytoSystems, Translational Plant Biology, University of Liège, 4000, Liège, Belgium
| | - Patrick Motte
- InBioS-PhytoSystems, Functional Genomics and Plant Molecular Imaging, University of Liège, 4000, Liège, Belgium
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2
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Rumaseb A, Moraes Barros RR, Sá JM, Juliano JJ, William T, Braima KA, Barber BE, Anstey NM, Price RN, Grigg MJ, Marfurt J, Auburn S. No Association between the Plasmodium vivax crt-o MS334 or In9 pvcrt Polymorphisms and Chloroquine Failure in a Pre-Elimination Clinical Cohort from Malaysia with a Large Clonal Expansion. Antimicrob Agents Chemother 2023; 67:e0161022. [PMID: 37314336 PMCID: PMC10353443 DOI: 10.1128/aac.01610-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 05/04/2023] [Indexed: 06/15/2023] Open
Abstract
Increasing reports of resistance to a frontline malaria blood-stage treatment, chloroquine (CQ), raises concerns for the elimination of Plasmodium vivax. The absence of an effective molecular marker of CQ resistance in P. vivax greatly constrains surveillance of this emerging threat. A recent genetic cross between CQ sensitive (CQS) and CQ resistant (CQR) NIH-1993 strains of P. vivax linked a moderate CQR phenotype with two candidate markers in P. vivax CQ resistance transporter gene (pvcrt-o): MS334 and In9pvcrt. Longer TGAAGH motif lengths at MS334 were associated with CQ resistance, as were shorter motifs at the In9pvcrt locus. In this study, high-grade CQR clinical isolates of P. vivax from a low endemic setting in Malaysia were used to investigate the association between the MS334 and In9pvcrt variants and treatment efficacy. Among a total of 49 independent monoclonal P. vivax isolates assessed, high-quality MS334 and In9pvcrt sequences could be derived from 30 (61%) and 23 (47%), respectively. Five MS334 and six In9pvcrt alleles were observed, with allele frequencies ranging from 2 to 76% and 3 to 71%, respectively. None of the clinical isolates had the same variant as the NIH-1993 CQR strain, and none of the variants were associated with CQ treatment failure (all P > 0.05). Multi-locus genotypes (MLGs) at 9 neutral microsatellites revealed a predominant P. vivax strain (MLG6) accounting for 52% of Day 0 infections. The MLG6 strain comprised equal proportions of CQS and CQR infections. Our study reveals complexity in the genetic basis of CQ resistance in the Malaysian P. vivax pre-elimination setting and suggests that the proposed pvcrt-o MS334 and In9pvcrt markers are not reliable markers of CQ treatment efficacy in this setting. Further studies are needed in other endemic settings, applying hypothesis-free genome-wide approaches, and functional approaches to understand the biological impact of the TGAAGH repeats linked to CQ response in a cross are warranted to comprehend and track CQR P. vivax.
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Affiliation(s)
- Angela Rumaseb
- Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, Northern Territory, Australia
| | - Roberto R. Moraes Barros
- Department of Microbiology, Immunology and Parasitology, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Juliana M. Sá
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Jonathan J. Juliano
- Division of Infectious Diseases, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Timothy William
- Clinical Research Centre, Queen Elizabeth Hospital, Sabah, Malaysia
- Infectious Diseases Society Sabah-Menzies School of Health Research Clinical Research Unit, Kota Kinabalu, Sabah, Malaysia
| | - Kamil A. Braima
- Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, Northern Territory, Australia
| | - Bridget E. Barber
- Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, Northern Territory, Australia
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Nicholas M. Anstey
- Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, Northern Territory, Australia
- Infectious Diseases Society Sabah-Menzies School of Health Research Clinical Research Unit, Kota Kinabalu, Sabah, Malaysia
| | - Ric N. Price
- Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, Northern Territory, Australia
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
- Mahidol-Oxford Tropical Medicine Research Unit, Mahidol University, Bangkok, Thailand
| | - Matthew J. Grigg
- Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, Northern Territory, Australia
- Infectious Diseases Society Sabah-Menzies School of Health Research Clinical Research Unit, Kota Kinabalu, Sabah, Malaysia
| | - Jutta Marfurt
- Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, Northern Territory, Australia
- College of Medicine and Public Health, Flinders University, Darwin, Northern Territory, Australia
| | - Sarah Auburn
- Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, Northern Territory, Australia
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
- Mahidol-Oxford Tropical Medicine Research Unit, Mahidol University, Bangkok, Thailand
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3
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Kobayashi NI, Takagi H, Yang X, Nishizawa-Yokoi A, Segawa T, Hoshina T, Oonishi T, Suzuki H, Iwata R, Toki S, Nakanishi TM, Tanoi K. Mutations in RZF1, a zinc-finger protein, reduce magnesium uptake in roots and translocation to shoots in rice. PLANT PHYSIOLOGY 2023; 192:342-355. [PMID: 36718554 PMCID: PMC10152673 DOI: 10.1093/plphys/kiad051] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 01/04/2023] [Accepted: 01/04/2023] [Indexed: 05/03/2023]
Abstract
Magnesium (Mg) homeostasis is critical for maintaining many biological processes, but little information is available to comprehend the molecular mechanisms regulating Mg concentration in rice (Oryza sativa). To make up for the lack of information, we aimed to identify mutants defective in Mg homeostasis through a forward genetic approach. As a result of the screening of 2,825 M2 seedlings mutated by ion-beam irradiation, we found a rice mutant that showed reduced Mg content in leaves and slightly increased Mg content in roots. Radiotracer 28Mg experiments showed that this mutant, named low-magnesium content 1 (LMGC1), has decreased Mg2+ influx in the root and Mg2+ translocation from root to shoot. Consequently, LMGC1 is sensitive to the low Mg condition and prone to develop chlorosis in the young mature leaf. The MutMap method identified a 7.4-kbp deletion in the LMGC1 genome leading to a loss of two genes. Genome editing using CRISPR-Cas9 further revealed that one of the two lost genes, a gene belonging to the RanBP2-type zinc-finger family that we named RanBP2-TYPE ZINC FINGER1 (OsRZF1), was the causal gene of the low Mg phenotype. OsRZF1 is a nuclear protein and may have a fundamental role in maintaining Mg homeostasis in rice plants.
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Affiliation(s)
- Natsuko I Kobayashi
- Graduate School of Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Hiroki Takagi
- Faculty of Bioresources and Environmental Sciences, Ishikawa Prefectural University, 1-308 Suematsu, Nonoichi, Ishikawa 921-8836, Japan
| | - Xiaoyu Yang
- Graduate School of Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Ayako Nishizawa-Yokoi
- Institute of Agrobiological Sciences, National Agriculture and Food Research Organization (NARO), 3-1-3 Kannondai, Tsukuba 305-8604, Japan
| | - Tenta Segawa
- Faculty of Bioresources and Environmental Sciences, Ishikawa Prefectural University, 1-308 Suematsu, Nonoichi, Ishikawa 921-8836, Japan
| | - Tatsuaki Hoshina
- Graduate School of Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Takayuki Oonishi
- Center for Education and Research of Community Collaboration, Utsunomiya University, Utsunomiya 321-8505, Japan
| | - Hisashi Suzuki
- National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Ren Iwata
- Cyclotron and Radioisotope Center (CYRIC), Tohoku University, 6-3 Aramaki Aza-Aoba, Aoba-ku, Sendai 980-8572, Japan
| | - Seiichi Toki
- Institute of Agrobiological Sciences, National Agriculture and Food Research Organization (NARO), 3-1-3 Kannondai, Tsukuba 305-8604, Japan
- Faculty of Agriculture, Ryukoku University, 1-5 Yokotani, Seta Oe-cho, Otsu, Shiga 520-2194, Japan
- Graduate School of Nanobioscience, Yokohama City University, 22-2 Seto, Yokohama, Kanagawa 236-0027, Japan
| | - Tomoko M Nakanishi
- Graduate School of Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
- Hoshi University, 2-4-41 Ebara, Shinagawa-Ku, Tokyo 142-8501, Japan
| | - Keitaro Tanoi
- Graduate School of Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
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4
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Bai B, van der Horst N, Cordewener JH, America AHP, Nijveen H, Bentsink L. Delayed Protein Changes During Seed Germination. FRONTIERS IN PLANT SCIENCE 2021; 12:735719. [PMID: 34603360 PMCID: PMC8480309 DOI: 10.3389/fpls.2021.735719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2021] [Accepted: 08/05/2021] [Indexed: 05/12/2023]
Abstract
Over the past decade, ample transcriptome data have been generated at different stages during seed germination; however, far less is known about protein synthesis during this important physiological process. Generally, the correlation between transcript levels and protein abundance is low, which strongly limits the use of transcriptome data to accurately estimate protein expression. Polysomal profiling has emerged as a tool to identify mRNAs that are actively translated. The association of the mRNA to the polysome, also referred to as translatome, provides a proxy for mRNA translation. In this study, the correlation between the changes in total mRNA, polysome-associated mRNA, and protein levels across seed germination was investigated. The direct correlation between polysomal mRNA and protein abundance at a single time-point during seed germination is low. However, once the polysomal mRNA of a time-point is compared to the proteome of the next time-point, the correlation is much higher. 35% of the investigated proteome has delayed changes at the protein level. Genes have been classified based on their delayed protein changes, and specific motifs in these genes have been identified. Moreover, mRNA and protein stability and mRNA length have been found as important predictors for changes in protein abundance. In conclusion, polysome association and/or dissociation predicts future changes in protein abundance in germinating seeds.
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Affiliation(s)
- Bing Bai
- Wageningen Seed Science Centre, Laboratory of Plant Physiology, Wageningen University, Wageningen, Netherlands
- *Correspondence: Bing Bai,
| | | | - Jan H. Cordewener
- BU Bioscience, Wageningen Plant Research, Wageningen, Netherlands
- Centre for BioSystems Genomics, Wageningen, Netherlands
- Netherlands Proteomics Centre, Utrecht, Netherlands
| | - Antoine H. P. America
- BU Bioscience, Wageningen Plant Research, Wageningen, Netherlands
- Centre for BioSystems Genomics, Wageningen, Netherlands
- Netherlands Proteomics Centre, Utrecht, Netherlands
| | - Harm Nijveen
- Bioinformatics Group, Wageningen University, Wageningen, Netherlands
| | - Leónie Bentsink
- Wageningen Seed Science Centre, Laboratory of Plant Physiology, Wageningen University, Wageningen, Netherlands
- Leónie Bentsink,
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5
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Lin BY, Shih CJ, Hsieh HY, Chen HC, Tu SL. Phytochrome Coordinates with a hnRNP to Regulate Alternative Splicing via an Exonic Splicing Silencer. PLANT PHYSIOLOGY 2020; 182:243-254. [PMID: 31501299 PMCID: PMC6945828 DOI: 10.1104/pp.19.00289] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Accepted: 08/24/2019] [Indexed: 05/25/2023]
Abstract
Plants perceive environmental light conditions and optimize their growth and development accordingly by regulating gene activity at multiple levels. Photoreceptors are important for light sensing and downstream gene regulation. Phytochromes, red/far-red light receptors, are believed to regulate light-responsive alternative splicing, but little is known about the underlying mechanism. Alternative splicing is primarily regulated by transacting factors, such as splicing regulators, and by cis-acting elements in precursor mRNA. In the moss Physcomitrella patens, we show that phytochrome 4 (PpPHY4) directly interacts with a splicing regulator, heterogeneous nuclear ribonucleoprotein F1 (PphnRNP-F1), in the nucleus to regulate light-responsive alternative splicing. RNA sequencing analysis revealed that PpPHY4 and PphnRNP-F1 coregulate 70% of intron retention (IR) events in response to red light. A repetitive GAA motif was identified to be an exonic splicing silencer that controls red light-responsive IR. Biochemical studies indicated that PphnRNP-F1 is recruited by the GAA motif to form RNA-protein complexes. Finally, red light elevates PphnRNP-F1 protein levels via PpPHY4, increasing levels of IR. We propose that PpPHY4 and PphnRNP-F1 regulate alternative splicing through an exonic splicing silencer to control splicing machinery activity in response to light.
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Affiliation(s)
- Bou-Yun Lin
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
- Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, Chung-Hsing University and Academia Sinica, Taipei 11529, Taiwan
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung 402, Taiwan
| | - Chueh-Ju Shih
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
- Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, Chung-Hsing University and Academia Sinica, Taipei 11529, Taiwan
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung 402, Taiwan
| | - Hsin-Yu Hsieh
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Hsiu-Chen Chen
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Shih-Long Tu
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
- Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, Chung-Hsing University and Academia Sinica, Taipei 11529, Taiwan
- Biotechnology Center, National Chung Hsing University, Taichung 402, Taiwan
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6
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Zappaterra M, Luise D, Zambonelli P, Mele M, Serra A, Costa LN, Davoli R. Association study between backfat fatty acid composition and SNPs in candidate genes highlights the effect of FASN polymorphism in large white pigs. Meat Sci 2019; 156:75-84. [DOI: 10.1016/j.meatsci.2019.05.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 05/08/2019] [Accepted: 05/13/2019] [Indexed: 12/30/2022]
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7
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Sá JM, Kaslow SR, Moraes Barros RR, Brazeau NF, Parobek CM, Tao D, Salzman RE, Gibson TJ, Velmurugan S, Krause MA, Melendez-Muniz V, Kite WA, Han PK, Eastman RT, Kim A, Kessler EG, Abebe Y, James ER, Chakravarty S, Orr-Gonzalez S, Lambert LE, Engels T, Thomas ML, Fasinu PS, Serre D, Gwadz RW, Walker L, DeConti DK, Mu J, Bailey JA, Sim BKL, Hoffman SL, Fay MP, Dinglasan RR, Juliano JJ, Wellems TE. Plasmodium vivax chloroquine resistance links to pvcrt transcription in a genetic cross. Nat Commun 2019; 10:4300. [PMID: 31541097 PMCID: PMC6754410 DOI: 10.1038/s41467-019-12256-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Accepted: 08/26/2019] [Indexed: 12/30/2022] Open
Abstract
Mainstay treatment for Plasmodium vivax malaria has long relied on chloroquine (CQ) against blood-stage parasites plus primaquine against dormant liver-stage forms (hypnozoites), however drug resistance confronts this regimen and threatens malaria control programs. Understanding the basis of P. vivax chloroquine resistance (CQR) will inform drug discovery and malaria control. Here we investigate the genetics of P. vivax CQR by a cross of parasites differing in drug response. Gametocytogenesis, mosquito infection, and progeny production are performed with mixed parasite populations in nonhuman primates, as methods for P. vivax cloning and in vitro cultivation remain unavailable. Linkage mapping of progeny surviving >15 mg/kg CQ identifies a 76 kb region in chromosome 1 including pvcrt, an ortholog of the Plasmodium falciparum CQR transporter gene. Transcriptional analysis supports upregulated pvcrt expression as a mechanism of CQR.
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Affiliation(s)
- Juliana M Sá
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Sarah R Kaslow
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Roberto R Moraes Barros
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Nicholas F Brazeau
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Christian M Parobek
- Curriculum in Genetics and Molecular Biology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Dingyin Tao
- W Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, 21205, USA
| | - Rebecca E Salzman
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Tyler J Gibson
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | | | - Michael A Krause
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Viviana Melendez-Muniz
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Whitney A Kite
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Paul K Han
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Richard T Eastman
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Adam Kim
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Evan G Kessler
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | | | | | | | - Sachy Orr-Gonzalez
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Lynn E Lambert
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Theresa Engels
- Division of Veterinary Resources, Office of Research Services, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Marvin L Thomas
- Division of Veterinary Resources, Office of Research Services, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Pius S Fasinu
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, Campbell University, Buies Creek, NC, 27506, USA
| | - David Serre
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Robert W Gwadz
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Larry Walker
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, Campbell University, Buies Creek, NC, 27506, USA
| | - Derrick K DeConti
- Program in Bioinformatics and Integrative Biology, University of Massachusetts Medical School, Worcester, MA, 01655, USA
| | - Jianbing Mu
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Jeffrey A Bailey
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, Campbell University, Buies Creek, NC, 27506, USA
- Division of Transfusion Medicine, Department of Medicine, University of Massachusetts Medical School, Worcester, MA, 01655, USA
| | | | | | - Michael P Fay
- Biostatistics Research Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, 20852, USA
| | - Rhoel R Dinglasan
- W Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, 21205, USA
- Emerging Pathogens Institute, Department of Infectious Diseases & Immunology, College of Veterinary Medicine, University of Florida, Gainesville, FL, 32611, USA
| | - Jonathan J Juliano
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC, 27599, USA
- Curriculum in Genetics and Molecular Biology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
- Division of Infectious Diseases, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Thomas E Wellems
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, 20892, USA.
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8
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Ling Z, Brockmöller T, Baldwin IT, Xu S. Evolution of Alternative Splicing in Eudicots. FRONTIERS IN PLANT SCIENCE 2019; 10:707. [PMID: 31244865 PMCID: PMC6581728 DOI: 10.3389/fpls.2019.00707] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 05/13/2019] [Indexed: 05/30/2023]
Abstract
Alternative pre-mRNA splicing (AS) is prevalent in plants and is involved in many interactions between plants and environmental stresses. However, the patterns and underlying mechanisms of AS evolution in plants remain unclear. By analyzing the transcriptomes of four eudicot species, we revealed that the divergence of AS is largely due to the gains and losses of AS events among orthologous genes. Furthermore, based on a subset of AS, in which AS can be directly associated with specific transcripts, we found that AS that generates transcripts containing premature termination codons (PTC), are likely more conserved than those that generate non-PTC containing transcripts. This suggests that AS coupled with nonsense-mediated decay (NMD) might play an important role in affecting mRNA levels post-transcriptionally. To understand the mechanisms underlying the divergence of AS, we analyzed the key determinants of AS using a machine learning approach. We found that the presence/absence of alternative splice site (SS) within the junction, the distance between the authentic SS and the nearest alternative SS, the size of exon-exon junctions were the major determinants for both alternative 5' donor site and 3' acceptor site among the studied species, suggesting a relatively conserved AS mechanism. The comparative analysis further demonstrated that variations of the identified AS determinants significantly contributed to the AS divergence among closely related species in both Solanaceae and Brassicaceae taxa. Together, these results provide detailed insights into the evolution of AS in plants.
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Affiliation(s)
- Zhihao Ling
- Max Planck Institute for Chemical Ecology, Jena, Germany
| | | | - Ian T. Baldwin
- Max Planck Institute for Chemical Ecology, Jena, Germany
| | - Shuqing Xu
- Plant Adaptation-in-action Group, Institute for Evolution and Biodiversity, University of Münster, Münster, Germany
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9
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Chen Q, Han Y, Liu H, Wang X, Sun J, Zhao B, Li W, Tian J, Liang Y, Yan J, Yang X, Tian F. Genome-Wide Association Analyses Reveal the Importance of Alternative Splicing in Diversifying Gene Function and Regulating Phenotypic Variation in Maize. THE PLANT CELL 2018; 30:1404-1423. [PMID: 29967286 PMCID: PMC6096592 DOI: 10.1105/tpc.18.00109] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 05/23/2018] [Accepted: 06/27/2018] [Indexed: 05/22/2023]
Abstract
Alternative splicing (AS) enhances transcriptome diversity and plays important roles in regulating plant processes. Although widespread natural variation in AS has been observed in plants, how AS is regulated and contribute to phenotypic variation is poorly understood. Here, we report a population-level transcriptome assembly and genome-wide association study to identify splicing quantitative trait loci (sQTLs) in developing maize (Zea mays) kernels from 368 inbred lines. We detected 19,554 unique sQTLs for 6570 genes. Most sQTLs showed small isoform usage changes without involving major isoform switching between genotypes. The sQTL-affected isoforms tend to display distinct protein functions. We demonstrate that nonsense-mediated mRNA decay, microRNA-mediated regulation, and small interfering peptide-mediated peptide interference are frequently involved in sQTL regulation. The natural variation in AS and overall mRNA level appears to be independently regulated with different cis-sequences preferentially used. We identified 214 putative trans-acting splicing regulators, among which ZmGRP1, encoding an hnRNP-like glycine-rich RNA binding protein, regulates the largest trans-cluster. Knockout of ZmGRP1 by CRISPR/Cas9 altered splicing of numerous downstream genes. We found that 739 sQTLs colocalized with previous marker-trait associations, most of which occurred without changes in overall mRNA level. Our findings uncover the importance of AS in diversifying gene function and regulating phenotypic variation.
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Affiliation(s)
- Qiuyue Chen
- National Maize Improvement Center of China, MOA Key Laboratory of Maize Biology, Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing 100193, China
| | - Yingjia Han
- National Maize Improvement Center of China, MOA Key Laboratory of Maize Biology, Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing 100193, China
- State Key Laboratory of Plant Physiology and Biochemistry, China Agricultural University, Beijing 100193, China
| | - Haijun Liu
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China
| | - Xufeng Wang
- National Maize Improvement Center of China, MOA Key Laboratory of Maize Biology, Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing 100193, China
| | - Jiamin Sun
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China
| | - Binghao Zhao
- National Maize Improvement Center of China, MOA Key Laboratory of Maize Biology, Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing 100193, China
- State Key Laboratory of Plant Physiology and Biochemistry, China Agricultural University, Beijing 100193, China
| | - Weiya Li
- National Maize Improvement Center of China, MOA Key Laboratory of Maize Biology, Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing 100193, China
- State Key Laboratory of Plant Physiology and Biochemistry, China Agricultural University, Beijing 100193, China
| | - Jinge Tian
- National Maize Improvement Center of China, MOA Key Laboratory of Maize Biology, Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing 100193, China
| | - Yameng Liang
- National Maize Improvement Center of China, MOA Key Laboratory of Maize Biology, Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing 100193, China
| | - Jianbing Yan
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China
| | - Xiaohong Yang
- National Maize Improvement Center of China, MOA Key Laboratory of Maize Biology, Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing 100193, China
- State Key Laboratory of Plant Physiology and Biochemistry, China Agricultural University, Beijing 100193, China
| | - Feng Tian
- National Maize Improvement Center of China, MOA Key Laboratory of Maize Biology, Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing 100193, China
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10
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Barbieri M. What is code biology? Biosystems 2018; 164:1-10. [DOI: 10.1016/j.biosystems.2017.10.005] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 10/04/2017] [Accepted: 10/05/2017] [Indexed: 01/29/2023]
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11
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Ullah F, Hamilton M, Reddy ASN, Ben-Hur A. Exploring the relationship between intron retention and chromatin accessibility in plants. BMC Genomics 2018; 19:21. [PMID: 29304739 PMCID: PMC5756433 DOI: 10.1186/s12864-017-4393-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Accepted: 12/15/2017] [Indexed: 11/29/2022] Open
Abstract
Background Intron retention (IR) is the most prevalent form of alternative splicing in plants. IR, like other forms of alternative splicing, has an important role in increasing gene product diversity and regulating transcript functionality. Splicing is known to occur co-transcriptionally and is influenced by the speed of transcription which in turn, is affected by chromatin structure. It follows that chromatin structure may have an important role in the regulation of splicing, and there is preliminary evidence in metazoans to suggest that this is indeed the case; however, nothing is known about the role of chromatin structure in regulating IR in plants. DNase I-seq is a useful experimental tool for genome-wide interrogation of chromatin accessibility, providing information on regions of chromatin with very high likelihood of cleavage by the enzyme DNase I, known as DNase I Hypersensitive Sites (DHSs). While it is well-established that promoter regions are highly accessible and are over-represented with DHSs, not much is known about DHSs in the bodies of genes, and their relationship to splicing in general, and IR in particular. Results In this study we use publicly available DNase I-seq data in arabidopsis and rice to investigate the relationship between IR and chromatin structure. We find that IR events are highly enriched in DHSs in both species. This implies that chromatin is more open in retained introns, which is consistent with a kinetic model of the process whereby higher speeds of transcription in those regions give less time for the spliceosomal machinery to recognize and splice out those introns co-transcriptionally. The more open chromatin in IR can also be the result of regulation mediated by DNA-binding proteins. To test this, we performed an exhaustive search for footprints left by DNA-binding proteins that are associated with IR. We identified several hundred short sequence elements that exhibit footprints in their DNase I-seq coverage, the telltale sign for binding events of a regulatory protein, protecting its binding site from cleavage by DNase I. A highly significant fraction of those sequence elements are conserved between arabidopsis and rice, a strong indication of their functional importance. Conclusions In this study we have established an association between IR and chromatin accessibility, and presented a mechanistic hypothesis that explains the observed association from the perspective of the co-transcriptional nature of splicing. Furthermore, we identified conserved sequence elements for DNA-binding proteins that affect splicing. Electronic supplementary material The online version of this article (10.1186/s12864-017-4393-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Fahad Ullah
- Computer Science Department, Colorado State University, 1873 Campus Delivery, Fort Collins, 80523, CO, USA
| | - Michael Hamilton
- Computer Science Department, Colorado State University, 1873 Campus Delivery, Fort Collins, 80523, CO, USA
| | - Anireddy S N Reddy
- Department of Biology, Colorado State University, 1878 Campus Delivery, Fort Collins, 80523, CO, USA
| | - Asa Ben-Hur
- Computer Science Department, Colorado State University, 1873 Campus Delivery, Fort Collins, 80523, CO, USA.
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12
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Vaneechoutte D, Estrada AR, Lin YC, Loraine AE, Vandepoele K. Genome-wide characterization of differential transcript usage in Arabidopsis thaliana. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2017; 92:1218-1231. [PMID: 29031026 DOI: 10.1111/tpj.13746] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 09/29/2017] [Accepted: 10/03/2017] [Indexed: 05/21/2023]
Abstract
Alternative splicing and the usage of alternate transcription start- or stop sites allows a single gene to produce multiple transcript isoforms. Most plant genes express certain isoforms at a significantly higher level than others, but under specific conditions this expression dominance can change, resulting in a different set of dominant isoforms. These events of differential transcript usage (DTU) have been observed for thousands of Arabidopsis thaliana, Zea mays and Vitis vinifera genes, and have been linked to development and stress response. However, neither the characteristics of these genes, nor the implications of DTU on their protein coding sequences or functions, are currently well understood. Here we present a dataset of isoform dominance and DTU for all genes in the AtRTD2 reference transcriptome based on a protocol that was benchmarked on simulated data and validated through comparison with a published reverse transciptase-polymerase chain reaction panel. We report DTU events for 8148 genes across 206 public RNA-Seq samples, and find that protein sequences are affected in 22% of the cases. The observed DTU events show high consistency across replicates, and reveal reproducible patterns in response to treatment and development. We also demonstrate that genes with different evolutionary ages, expression breadths and functions show large differences in the frequency at which they undergo DTU, and in the effect that these events have on their protein sequences. Finally, we showcase how the generated dataset can be used to explore DTU events for genes of interest or to find genes with specific DTU in samples of interest.
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Affiliation(s)
- Dries Vaneechoutte
- VIB Center for Plant Systems Biology, VIB, Technologiepark 927, B-9052, Gent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 927, B-9052, Gent, Belgium
| | - April R Estrada
- Department of Bioinformatics and Genomics, University of North Carolina at Charlotte, North Carolina Research Campus, Kannapolis, NC, 28081, USA
| | - Ying-Chen Lin
- Department of Bioinformatics and Genomics, University of North Carolina at Charlotte, North Carolina Research Campus, Kannapolis, NC, 28081, USA
| | - Ann E Loraine
- Department of Bioinformatics and Genomics, University of North Carolina at Charlotte, North Carolina Research Campus, Kannapolis, NC, 28081, USA
| | - Klaas Vandepoele
- VIB Center for Plant Systems Biology, VIB, Technologiepark 927, B-9052, Gent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 927, B-9052, Gent, Belgium
- Bioinformatics Institute Ghent, Ghent University, Technologiepark 927, 9052, Ghent, Belgium
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13
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Wang K, Jiao Z, Xu M, Wang Y, Li R, Cui X, Gu L, Zhang S. Landscape and Fruit Developmental Regulation of Alternative Splicing in Tomato by Genome-Wide Analysis. HORTICULTURAL PLANT JOURNAL 2016; 2:338-350. [PMID: 0 DOI: 10.1016/j.hpj.2017.01.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
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14
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15
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Ma MY, Lan XR, Niu DK. Intron gain by tandem genomic duplication: a novel case in a potato gene encoding RNA-dependent RNA polymerase. PeerJ 2016; 4:e2272. [PMID: 27547574 PMCID: PMC4974935 DOI: 10.7717/peerj.2272] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 06/29/2016] [Indexed: 01/15/2023] Open
Abstract
The origin and subsequent accumulation of spliceosomal introns are prominent events in the evolution of eukaryotic gene structure. However, the mechanisms underlying intron gain remain unclear because there are few proven cases of recently gained introns. In an RNA-dependent RNA polymerase (RdRp) gene, we found that a tandem duplication occurred after the divergence of potato and its wild relatives among other Solanum plants. The duplicated sequence crosses the intron-exon boundary of the first intron and the second exon. A new intron was detected at this duplicated region, and it includes a small previously exonic segment of the upstream copy of the duplicated sequence and the intronic segment of the downstream copy of the duplicated sequence. The donor site of this new intron was directly obtained from the small previously exonic segment. Most of the splicing signals were inherited directly from the parental intron/exon structure, including a putative branch site, the polypyrimidine tract, the 3' splicing site, two putative exonic splicing enhancers, and the GC contents differed between the intron and exon. In the widely cited model of intron gain by tandem genomic duplication, the duplication of an AGGT-containing exonic segment provides the GT and AG splicing sites for the new intron. Our results illustrate that the tandem duplication model of intron gain should be diverse in terms of obtaining the proper splicing signals.
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Affiliation(s)
- Ming-Yue Ma
- MOE Key Laboratory for Biodiversity Science and Ecological Engineering and Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University , Beijing , China
| | - Xin-Ran Lan
- MOE Key Laboratory for Biodiversity Science and Ecological Engineering and Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University , Beijing , China
| | - Deng-Ke Niu
- MOE Key Laboratory for Biodiversity Science and Ecological Engineering and Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University , Beijing , China
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16
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17
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Barbieri M. A new theory of development: the generation of complexity in ontogenesis. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2016; 374:rsta.2015.0148. [PMID: 26857661 DOI: 10.1098/rsta.2015.0148] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 08/01/2015] [Indexed: 06/05/2023]
Abstract
Today there is a very wide consensus on the idea that embryonic development is the result of a genetic programme and of epigenetic processes. Many models have been proposed in this theoretical framework to account for the various aspects of development, and virtually all of them have one thing in common: they do not acknowledge the presence of organic codes (codes between organic molecules) in ontogenesis. Here it is argued instead that embryonic development is a convergent increase in complexity that necessarily requires organic codes and organic memories, and a few examples of such codes are described. This is the code theory of development, a theory that was originally inspired by an algorithm that is capable of reconstructing structures from incomplete information, an algorithm that here is briefly summarized because it makes it intuitively appealing how a convergent increase in complexity can be achieved. The main thesis of the new theory is that the presence of organic codes in ontogenesis is not only a theoretical necessity but, first and foremost, an idea that can be tested and that has already been found to be in agreement with the evidence.
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Affiliation(s)
- Marcello Barbieri
- Dipartimento di Morfologia ed Embriologia, via Fossato di Mortara 64a, Ferrara 44121, Italy
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18
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Thatcher SR, Danilevskaya ON, Meng X, Beatty M, Zastrow-Hayes G, Harris C, Van Allen B, Habben J, Li B. Genome-Wide Analysis of Alternative Splicing during Development and Drought Stress in Maize. PLANT PHYSIOLOGY 2016; 170:586-99. [PMID: 26582726 PMCID: PMC4704579 DOI: 10.1104/pp.15.01267] [Citation(s) in RCA: 92] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 11/17/2015] [Indexed: 05/18/2023]
Abstract
Alternative splicing plays a crucial role in plant development as well as stress responses. Although alternative splicing has been studied during development and in response to stress, the interplay between these two factors remains an open question. To assess the effects of drought stress on developmentally regulated splicing in maize (Zea mays), 94 RNA-seq libraries from ear, tassel, and leaf of the B73 public inbred line were constructed at four developmental stages under both well-watered and drought conditions. This analysis was supplemented with a publicly available series of 53 libraries from developing seed, embryo, and endosperm. More than 48,000 novel isoforms, often with stage- or condition-specific expression, were uncovered, suggesting that developmentally regulated alternative splicing occurs in thousands of genes. Drought induced large developmental splicing changes in leaf and ear but relatively few in tassel. Most developmental stage-specific splicing changes affected by drought were tissue dependent, whereas stage-independent changes frequently overlapped between leaf and ear. A linear relationship was found between gene expression changes in splicing factors and alternative spicing of other genes during development. Collectively, these results demonstrate that alternative splicing is strongly associated with tissue type, developmental stage, and stress condition.
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Affiliation(s)
- Shawn R Thatcher
- DuPont Pioneer, Wilmington, Delaware 19880 (S.R.T., B.L.); andDuPont Pioneer, Johnston, Iowa 50131 (O.N.D., X.M., M.B., G.Z.-H., C.H., B.V.A., J.H.)
| | - Olga N Danilevskaya
- DuPont Pioneer, Wilmington, Delaware 19880 (S.R.T., B.L.); andDuPont Pioneer, Johnston, Iowa 50131 (O.N.D., X.M., M.B., G.Z.-H., C.H., B.V.A., J.H.)
| | - Xin Meng
- DuPont Pioneer, Wilmington, Delaware 19880 (S.R.T., B.L.); andDuPont Pioneer, Johnston, Iowa 50131 (O.N.D., X.M., M.B., G.Z.-H., C.H., B.V.A., J.H.)
| | - Mary Beatty
- DuPont Pioneer, Wilmington, Delaware 19880 (S.R.T., B.L.); andDuPont Pioneer, Johnston, Iowa 50131 (O.N.D., X.M., M.B., G.Z.-H., C.H., B.V.A., J.H.)
| | - Gina Zastrow-Hayes
- DuPont Pioneer, Wilmington, Delaware 19880 (S.R.T., B.L.); andDuPont Pioneer, Johnston, Iowa 50131 (O.N.D., X.M., M.B., G.Z.-H., C.H., B.V.A., J.H.)
| | - Charlotte Harris
- DuPont Pioneer, Wilmington, Delaware 19880 (S.R.T., B.L.); andDuPont Pioneer, Johnston, Iowa 50131 (O.N.D., X.M., M.B., G.Z.-H., C.H., B.V.A., J.H.)
| | - Brandon Van Allen
- DuPont Pioneer, Wilmington, Delaware 19880 (S.R.T., B.L.); andDuPont Pioneer, Johnston, Iowa 50131 (O.N.D., X.M., M.B., G.Z.-H., C.H., B.V.A., J.H.)
| | - Jeffrey Habben
- DuPont Pioneer, Wilmington, Delaware 19880 (S.R.T., B.L.); andDuPont Pioneer, Johnston, Iowa 50131 (O.N.D., X.M., M.B., G.Z.-H., C.H., B.V.A., J.H.)
| | - Bailin Li
- DuPont Pioneer, Wilmington, Delaware 19880 (S.R.T., B.L.); andDuPont Pioneer, Johnston, Iowa 50131 (O.N.D., X.M., M.B., G.Z.-H., C.H., B.V.A., J.H.)
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19
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Xing D, Wang Y, Hamilton M, Ben-Hur A, Reddy ASN. Transcriptome-Wide Identification of RNA Targets of Arabidopsis SERINE/ARGININE-RICH45 Uncovers the Unexpected Roles of This RNA Binding Protein in RNA Processing. THE PLANT CELL 2015; 27:3294-308. [PMID: 26603559 PMCID: PMC4707455 DOI: 10.1105/tpc.15.00641] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Revised: 10/19/2015] [Accepted: 11/03/2015] [Indexed: 05/20/2023]
Abstract
Plant SR45 and its metazoan ortholog RNPS1 are serine/arginine-rich (SR)-like RNA binding proteins that function in splicing/postsplicing events and regulate diverse processes in eukaryotes. Interactions of SR45 with both RNAs and proteins are crucial for regulating RNA processing. However, in vivo RNA targets of SR45 are currently unclear. Using RNA immunoprecipitation followed by high-throughput sequencing, we identified over 4000 Arabidopsis thaliana RNAs that directly or indirectly associate with SR45, designated as SR45-associated RNAs (SARs). Comprehensive analyses of these SARs revealed several roles for SR45. First, SR45 associates with and regulates the expression of 30% of abscisic acid (ABA) signaling genes at the postsplicing level. Second, although most SARs are derived from intron-containing genes, surprisingly, 340 SARs are derived from intronless genes. Expression analysis of the SARs suggests that SR45 differentially regulates intronless and intron-containing SARs. Finally, we identified four overrepresented RNA motifs in SARs that likely mediate SR45's recognition of its targets. Therefore, SR45 plays an unexpected role in mRNA processing of intronless genes, and numerous ABA signaling genes are targeted for regulation at the posttranscriptional level. The diverse molecular functions of SR45 uncovered in this study are likely applicable to other species in view of its conservation across eukaryotes.
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Affiliation(s)
- Denghui Xing
- Department of Biology and Program in Molecular Plant Biology, Colorado State University, Fort Collins, Colorado 80523
| | - Yajun Wang
- Department of Biology and Program in Molecular Plant Biology, Colorado State University, Fort Collins, Colorado 80523
| | - Michael Hamilton
- Computer Science Department, Colorado State University, Fort Collins, Colorado 80523
| | - Asa Ben-Hur
- Computer Science Department, Colorado State University, Fort Collins, Colorado 80523
| | - Anireddy S N Reddy
- Department of Biology and Program in Molecular Plant Biology, Colorado State University, Fort Collins, Colorado 80523
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20
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Panahi B, Mohammadi SA, Khaksefidi RE, Fallah Mehrabadi J, Ebrahimie E. Genome-wide analysis of alternative splicing events inHordeum vulgare: Highlighting retention of intron-based splicing and its possible function through network analysis. FEBS Lett 2015; 589:3564-75. [DOI: 10.1016/j.febslet.2015.09.023] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Revised: 09/15/2015] [Accepted: 09/23/2015] [Indexed: 11/29/2022]
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21
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Badr E, Heath LS. CoSREM: a graph mining algorithm for the discovery of combinatorial splicing regulatory elements. BMC Bioinformatics 2015; 16:285. [PMID: 26337677 PMCID: PMC4559876 DOI: 10.1186/s12859-015-0698-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 08/06/2015] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Alternative splicing (AS) is a post-transcriptional regulatory mechanism for gene expression regulation. Splicing decisions are affected by the combinatorial behavior of different splicing factors that bind to multiple binding sites in exons and introns. These binding sites are called splicing regulatory elements (SREs). Here we develop CoSREM (Combinatorial SRE Miner), a graph mining algorithm to discover combinatorial SREs in human exons. Our model does not assume a fixed length of SREs and incorporates experimental evidence as well to increase accuracy. CoSREM is able to identify sets of SREs and is not limited to SRE pairs as are current approaches. RESULTS We identified 37 SRE sets that include both enhancer and silencer elements. We show that our results intersect with previous results, including some that are experimental. We also show that the SRE set GGGAGG and GAGGAC identified by CoSREM may play a role in exon skipping events in several tumor samples. We applied CoSREM to RNA-Seq data for multiple tissues to identify combinatorial SREs which may be responsible for exon inclusion or exclusion across tissues. CONCLUSION The new algorithm can identify different combinations of splicing enhancers and silencers without assuming a predefined size or limiting the algorithm to find only pairs of SREs. Our approach opens new directions to study SREs and the roles that AS may play in diseases and tissue specificity.
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Affiliation(s)
- Eman Badr
- Department of Computer Science, Virginia Tech, Blacksburg, Virginia, USA
| | - Lenwood S Heath
- Department of Computer Science, Virginia Tech, Blacksburg, Virginia, USA.
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22
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Badr E, Heath LS. Identifying splicing regulatory elements with de Bruijn graphs. J Comput Biol 2015; 21:880-97. [PMID: 25393830 DOI: 10.1089/cmb.2014.0183] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Splicing regulatory elements (SREs) are short, degenerate sequences on pre-mRNA molecules that enhance or inhibit the splicing process via the binding of splicing factors, proteins that regulate the functioning of the spliceosome. Existing methods for identifying SREs in a genome are either experimental or computational. Here, we propose a formalism based on de Bruijn graphs that combines genomic structure, word count enrichment analysis, and experimental evidence to identify SREs found in exons. In our approach, SREs are not restricted to a fixed length (i.e., k-mers, for a fixed k). As a result, we identify 2001 putative exonic enhancers and 3080 putative exonic silencers for human genes, with lengths varying from 6 to 15 nucleotides. Many of the predicted SREs overlap with experimentally verified binding sites. Our model provides a novel method to predict variable length putative regulatory elements computationally for further experimental investigation.
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Affiliation(s)
- Eman Badr
- Department of Computer Science, Virginia Tech , Blacksburg, Virginia
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23
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Bush SJ, Kover PX, Urrutia AO. Lineage-specific sequence evolution and exon edge conservation partially explain the relationship between evolutionary rate and expression level in A. thaliana. Mol Ecol 2015; 24:3093-106. [PMID: 25930165 PMCID: PMC4480654 DOI: 10.1111/mec.13221] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Revised: 04/21/2015] [Accepted: 04/28/2015] [Indexed: 02/06/2023]
Abstract
Rapidly evolving proteins can aid the identification of genes underlying phenotypic adaptation across taxa, but functional and structural elements of genes can also affect evolutionary rates. In plants, the ‘edges’ of exons, flanking intron junctions, are known to contain splice enhancers and to have a higher degree of conservation compared to the remainder of the coding region. However, the extent to which these regions may be masking indicators of positive selection or account for the relationship between dN/dS and other genomic parameters is unclear. We investigate the effects of exon edge conservation on the relationship of dN/dS to various sequence characteristics and gene expression parameters in the model plant Arabidopsis thaliana. We also obtain lineage-specific dN/dS estimates, making use of the recently sequenced genome of Thellungiella parvula, the second closest sequenced relative after the sister species Arabidopsis lyrata. Overall, we find that the effect of exon edge conservation, as well as the use of lineage-specific substitution estimates, upon dN/dS ratios partly explains the relationship between the rates of protein evolution and expression level. Furthermore, the removal of exon edges shifts dN/dS estimates upwards, increasing the proportion of genes potentially under adaptive selection. We conclude that lineage-specific substitutions and exon edge conservation have an important effect on dN/dS ratios and should be considered when assessing their relationship with other genomic parameters.
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Affiliation(s)
- Stephen J Bush
- Department of Biology and Biochemistry, University of Bath, Bath, BA2 7AY, UK
| | - Paula X Kover
- Department of Biology and Biochemistry, University of Bath, Bath, BA2 7AY, UK
| | - Araxi O Urrutia
- Department of Biology and Biochemistry, University of Bath, Bath, BA2 7AY, UK
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Chan YW, Millard AD, Wheatley PJ, Holmes AB, Mohr R, Whitworth AL, Mann NH, Larkum AWD, Hess WR, Scanlan DJ, Clokie MRJ. Genomic and proteomic characterization of two novel siphovirus infecting the sedentary facultative epibiont cyanobacterium Acaryochloris marina. Environ Microbiol 2015; 17:4239-52. [PMID: 25472545 DOI: 10.1111/1462-2920.12735] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Revised: 11/26/2014] [Accepted: 11/27/2003] [Indexed: 11/28/2022]
Abstract
Acaryochloris marina is a symbiotic species of cyanobacteria that is capable of utilizing far-red light. We report the characterization of the phages A-HIS1 and A-HIS2, capable of infecting Acaryochloris. Morphological characterization of these phages places them in the family Siphoviridae. However, molecular characterization reveals that they do not show genetic similarity with any known siphoviruses. While the phages do show synteny between each other, the nucleotide identity between the phages is low at 45-67%, suggesting they diverged from each other some time ago. The greatest number of genes shared with another phage (a myovirus infecting marine Synechococcus) was four. Unlike most other cyanophages and in common with the Siphoviridae infecting Synechococcus, no photosynthesis-related genes were found in the genome. CRISPR (clustered regularly interspaced short palindromic repeats) spacers from the host Acaryochloris had partial matches to sequences found within the phages, which is the first time CRISPRs have been reported in a cyanobacterial/cyanophage system. The phages also encode a homologue of the proteobacterial RNase T. The potential function of RNase T in the mark-up or digestion of crRNA hints at a novel mechanism for evading the host CRISPR system.
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Affiliation(s)
- Yi-Wah Chan
- Warwick Systems Biology Centre, Coventry, UK
| | | | | | - Antony B Holmes
- Institute for Cancer Genetics, Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY, USA
| | - Remus Mohr
- Genetics and Experimental Bioinformatics, Faculty of Biology, University of Freiburg, Freiburg, Germany
| | | | - Nicholas H Mann
- School of Life Sciences, University of Warwick, Coventry, UK
| | - Anthony W D Larkum
- School of Biological Sciences, University of Sydney, Sydney, NSW, Australia
| | - Wolfgang R Hess
- Institute of Biology III, University of Freiburg, Freiburg, Germany
| | - David J Scanlan
- School of Life Sciences, University of Warwick, Coventry, UK
| | - Martha R J Clokie
- Department of Infection, Immunity and Inflammation, University of Leicester, Leicester, LE19HN, UK
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Thatcher SR, Zhou W, Leonard A, Wang BB, Beatty M, Zastrow-Hayes G, Zhao X, Baumgarten A, Li B. Genome-wide analysis of alternative splicing in Zea mays: landscape and genetic regulation. THE PLANT CELL 2014; 26:3472-87. [PMID: 25248552 PMCID: PMC4213170 DOI: 10.1105/tpc.114.130773] [Citation(s) in RCA: 148] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Revised: 08/07/2014] [Accepted: 09/10/2014] [Indexed: 05/18/2023]
Abstract
Alternative splicing enhances transcriptome diversity in all eukaryotes and plays a role in plant tissue identity and stress adaptation. To catalog new maize (Zea mays) transcripts and identify genomic loci that regulate alternative splicing, we analyzed over 90 RNA-seq libraries from maize inbred lines B73 and Mo17, as well as Syn10 doubled haploid lines (progenies from B73 × Mo17). Transcript discovery was augmented with publicly available data from 14 maize tissues, expanding the maize transcriptome by more than 30,000 and increasing the percentage of intron-containing genes that undergo alternative splicing to 40%. These newly identified transcripts greatly increase the diversity of the maize proteome, sometimes coding for entirely different proteins compared with their most similar annotated isoform. In addition to increasing proteome diversity, many genes encoding novel transcripts gained an additional layer of regulation by microRNAs, often in a tissue-specific manner. We also demonstrate that the majority of genotype-specific alternative splicing can be genetically mapped, with cis-acting quantitative trait loci (QTLs) predominating. A large number of trans-acting QTLs were also apparent, with nearly half located in regions not shown to contain genes associated with splicing. Taken together, these results highlight the currently underappreciated role that alternative splicing plays in tissue identity and genotypic variation in maize.
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Affiliation(s)
| | | | | | - Bing-Bing Wang
- DuPont Pioneer, Johnston, Iowa 50131 Huazhi Rice Biotech Company, Changsha, Hunan 410125, China
| | | | | | - Xiangyu Zhao
- DuPont Pioneer, Wilmington, Delaware 19880 Shandong Agricultural University, Shandong 271000, China
| | | | - Bailin Li
- DuPont Pioneer, Wilmington, Delaware 19880
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Mao R, Raj Kumar PK, Guo C, Zhang Y, Liang C. Comparative analyses between retained introns and constitutively spliced introns in Arabidopsis thaliana using random forest and support vector machine. PLoS One 2014; 9:e104049. [PMID: 25110928 PMCID: PMC4128822 DOI: 10.1371/journal.pone.0104049] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Accepted: 07/06/2014] [Indexed: 01/04/2023] Open
Abstract
One of the important modes of pre-mRNA post-transcriptional modification is alternative splicing. Alternative splicing allows creation of many distinct mature mRNA transcripts from a single gene by utilizing different splice sites. In plants like Arabidopsis thaliana, the most common type of alternative splicing is intron retention. Many studies in the past focus on positional distribution of retained introns (RIs) among different genic regions and their expression regulations, while little systematic classification of RIs from constitutively spliced introns (CSIs) has been conducted using machine learning approaches. We used random forest and support vector machine (SVM) with radial basis kernel function (RBF) to differentiate these two types of introns in Arabidopsis. By comparing coordinates of introns of all annotated mRNAs from TAIR10, we obtained our high-quality experimental data. To distinguish RIs from CSIs, We investigated the unique characteristics of RIs in comparison with CSIs and finally extracted 37 quantitative features: local and global nucleotide sequence features of introns, frequent motifs, the signal strength of splice sites, and the similarity between sequences of introns and their flanking regions. We demonstrated that our proposed feature extraction approach was more accurate in effectively classifying RIs from CSIs in comparison with other four approaches. The optimal penalty parameter C and the RBF kernel parameter in SVM were set based on particle swarm optimization algorithm (PSOSVM). Our classification performance showed F-Measure of 80.8% (random forest) and 77.4% (PSOSVM). Not only the basic sequence features and positional distribution characteristics of RIs were obtained, but also putative regulatory motifs in intron splicing were predicted based on our feature extraction approach. Clearly, our study will facilitate a better understanding of underlying mechanisms involved in intron retention.
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Affiliation(s)
- Rui Mao
- College of Mechanical and Electronic Engineering, Northwest A&F University, Yangling, Shaanxi, China
- College of Information Engineering, Northwest A&F University, Yangling, Shaanxi, China
- Department of Biology, Miami University, Oxford, Ohio, United States of America
| | | | - Cheng Guo
- Department of Biology, Miami University, Oxford, Ohio, United States of America
| | - Yang Zhang
- College of Mechanical and Electronic Engineering, Northwest A&F University, Yangling, Shaanxi, China
- College of Information Engineering, Northwest A&F University, Yangling, Shaanxi, China
- * E-mail: (YZ); (CL)
| | - Chun Liang
- Department of Biology, Miami University, Oxford, Ohio, United States of America
- Department of Computer Sciences and Software Engineering, Miami University, Oxford, Ohio, United States of America
- * E-mail: (YZ); (CL)
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Simpson CG, Lewandowska D, Liney M, Davidson D, Chapman S, Fuller J, McNicol J, Shaw P, Brown JWS. Arabidopsis PTB1 and PTB2 proteins negatively regulate splicing of a mini-exon splicing reporter and affect alternative splicing of endogenous genes differentially. THE NEW PHYTOLOGIST 2014; 203:424-436. [PMID: 24749484 DOI: 10.1111/nph.12821] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Accepted: 03/14/2013] [Indexed: 06/03/2023]
Abstract
This paper examines the function of Arabidopsis thaliana AtPTB1 and AtPTB2 as plant splicing factors. The effect on splicing of overexpression of AtPTB1 and AtPTB2 was analysed in an in vivo protoplast transient expression system with a novel mini-exon splicing reporter. A range of mutations in pyrimidine-rich sequences were compared with and without AtPTB and NpU2AF65 overexpression. Splicing analyses of constructs in protoplasts and RNA from overexpression lines used high-resolution reverse transcription polymerase chain reaction (RT-PCR). AtPTB1 and AtPTB2 reduced inclusion/splicing of the potato invertase mini-exon splicing reporter, indicating that these proteins can repress plant intron splicing. Mutation of the polypyrimidine tract and closely associated Cytosine and Uracil-rich (CU-rich) sequences, upstream of the mini-exon, altered repression by AtPTB1 and AtPTB2. Coexpression of a plant orthologue of U2AF65 alleviated the splicing repression of AtPTB1. Mutation of a second CU-rich upstream of the mini-exon 3' splice site led to a decline in mini-exon splicing, indicating the presence of a splicing enhancer sequence. Finally, RT-PCR of AtPTB overexpression lines with c. 90 known alternative splicing (AS) events showed that AtPTBs significantly altered AS of over half the events. AtPTB1 and AtPTB2 are splicing factors that influence alternative splicing. This occurs in the potato invertase mini-exon via the polypyrimidine tract and associated pyrimidine-rich sequence.
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Affiliation(s)
- Craig G Simpson
- Cell and Molecular Sciences, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK
| | - Dominika Lewandowska
- Cell and Molecular Sciences, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK
| | - Michele Liney
- Cell and Molecular Sciences, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK
| | - Diane Davidson
- Cell and Molecular Sciences, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK
| | - Sean Chapman
- Cell and Molecular Sciences, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK
| | - John Fuller
- Cell and Molecular Sciences, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK
| | - Jim McNicol
- Biomathematics and Statistics Scotland, Invergowrie, Dundee, DD2 5DA, UK
| | - Paul Shaw
- Information and Computational Sciences, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK
| | - John W S Brown
- Cell and Molecular Sciences, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK
- Division of Plant Sciences, University of Dundee at JHI, Invergowrie, Dundee, DD2 5DA, UK
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Chang CY, Lin WD, Tu SL. Genome-Wide Analysis of Heat-Sensitive Alternative Splicing in Physcomitrella patens. PLANT PHYSIOLOGY 2014; 165:826-840. [PMID: 24777346 PMCID: PMC4044832 DOI: 10.1104/pp.113.230540] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Plant growth and development are constantly influenced by temperature fluctuations. To respond to temperature changes, different levels of gene regulation are modulated in the cell. Alternative splicing (AS) is a widespread mechanism increasing transcriptome complexity and proteome diversity. Although genome-wide studies have revealed complex AS patterns in plants, whether AS impacts the stress defense of plants is not known. We used heat shock (HS) treatments at nondamaging temperature and messenger RNA sequencing to obtain HS transcriptomes in the moss Physcomitrella patens. Data analysis identified a significant number of novel AS events in the moss protonema. Nearly 50% of genes are alternatively spliced. Intron retention (IR) is markedly repressed under elevated temperature but alternative donor/acceptor site and exon skipping are mainly induced, indicating differential regulation of AS in response to heat stress. Transcripts undergoing heat-sensitive IR are mostly involved in specific functions, which suggests that plants regulate AS with transcript specificity under elevated temperature. An exonic GAG-repeat motif in these IR regions may function as a regulatory cis-element in heat-mediated AS regulation. A conserved AS pattern for HS transcription factors in P. patens and Arabidopsis (Arabidopsis thaliana) reveals that heat regulation for AS evolved early during land colonization of green plants. Our results support that AS of specific genes, including key HS regulators, is fine-tuned under elevated temperature to modulate gene regulation and reorganize metabolic processes.
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Affiliation(s)
- Chiung-Yun Chang
- Institute of Plant and Microbial Biology (C.-Y.C., W.-D.L., S.-L.T.) and Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program (C.-Y.C., S.-L.T.), Academia Sinica, Taipei 11529, Taiwan; andGraduate Institute of Biotechnology (C.-Y.C.) and Biotechnology Center (S.-L.T.), National Chung-Hsing University, Taichung 402, Taiwan
| | - Wen-Dar Lin
- Institute of Plant and Microbial Biology (C.-Y.C., W.-D.L., S.-L.T.) and Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program (C.-Y.C., S.-L.T.), Academia Sinica, Taipei 11529, Taiwan; andGraduate Institute of Biotechnology (C.-Y.C.) and Biotechnology Center (S.-L.T.), National Chung-Hsing University, Taichung 402, Taiwan
| | - Shih-Long Tu
- Institute of Plant and Microbial Biology (C.-Y.C., W.-D.L., S.-L.T.) and Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program (C.-Y.C., S.-L.T.), Academia Sinica, Taipei 11529, Taiwan; andGraduate Institute of Biotechnology (C.-Y.C.) and Biotechnology Center (S.-L.T.), National Chung-Hsing University, Taichung 402, Taiwan
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Abstract
Rice is a monocot gramineous crop, and one of the most important staple foods. Rice is considered a model species for most gramineous crops. Extensive research on rice has provided critical guidance for other crops, such as maize and wheat. In recent years, climate change and exacerbated soil degradation have resulted in a variety of abiotic stresses, such as greenhouse effects, lower temperatures, drought, floods, soil salinization and heavy metal pollution. As such, there is an extremely high demand for additional research, in order to address these negative factors. Studies have shown that the alternative splicing of many genes in rice is affected by stress conditions, suggesting that manipulation of the alternative splicing of specific genes may be an effective approach for rice to adapt to abiotic stress. With the advancement of microarrays, and more recently, next generation sequencing technology, several studies have shown that more than half of the genes in the rice genome undergo alternative splicing. This mini-review summarizes the latest progress in the research of splicing and alternative splicing in rice, compared to splicing in humans. Furthermore, we discuss how additional studies may change the landscape of investigation of rice functional genomics and genetically improved rice. [BMB Reports 2013; 46(9): 439-447]
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Affiliation(s)
- Zhiguo E
- Nantong University, Nantong 226001, P.R. China ;
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30
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Wu HP, Su YS, Chen HC, Chen YR, Wu CC, Lin WD, Tu SL. Genome-wide analysis of light-regulated alternative splicing mediated by photoreceptors in Physcomitrella patens. Genome Biol 2014; 15:R10. [PMID: 24398233 PMCID: PMC4054894 DOI: 10.1186/gb-2014-15-1-r10] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Accepted: 01/07/2014] [Indexed: 12/22/2022] Open
Abstract
Background Light is one of the most important factors regulating plant growth and development. Light-sensing photoreceptors tightly regulate gene expression to control photomorphogenic responses. Although many levels of gene expression are modulated by photoreceptors, regulation at the mRNA splicing step remains unclear. Results We performed high-throughput mRNA sequencing to analyze light-responsive changes in alternative splicing in the moss Physcomitrella patens, and found that a large number of alternative splicing events were induced by light in the moss protonema. Light-responsive intron retention preferentially occurred in transcripts involved in photosynthesis and translation. Many of the alternatively spliced transcripts were expressed from genes with a function relating to splicing or light signaling, suggesting a potential impact on pre-mRNA splicing and photomorphogenic gene regulation in response to light. Moreover, most light-regulated intron retention was induced immediately upon light exposure, while motif analysis identified a repetitive GAA motif that may function as an exonic regulatory cis element in light-mediated alternative splicing. Further analysis in gene-disrupted mutants was consistent with a function for multiple red-light photoreceptors in the upstream regulation of light-responsive alternative splicing. Conclusions Our results indicate that intensive alternative splicing occurs in non-vascular plants and that, during photomorphogenesis, light regulates alternative splicing with transcript selectivity. We further suggest that alternative splicing is rapidly fine-tuned by light to modulate gene expression and reorganize metabolic processes, and that pre-mRNA cis elements are involved in photoreceptor-mediated splicing regulation.
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Reddy AS, Marquez Y, Kalyna M, Barta A. Complexity of the alternative splicing landscape in plants. THE PLANT CELL 2013; 25:3657-83. [PMID: 24179125 PMCID: PMC3877793 DOI: 10.1105/tpc.113.117523] [Citation(s) in RCA: 516] [Impact Index Per Article: 46.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2013] [Revised: 09/27/2013] [Accepted: 10/08/2013] [Indexed: 05/18/2023]
Abstract
Alternative splicing (AS) of precursor mRNAs (pre-mRNAs) from multiexon genes allows organisms to increase their coding potential and regulate gene expression through multiple mechanisms. Recent transcriptome-wide analysis of AS using RNA sequencing has revealed that AS is highly pervasive in plants. Pre-mRNAs from over 60% of intron-containing genes undergo AS to produce a vast repertoire of mRNA isoforms. The functions of most splice variants are unknown. However, emerging evidence indicates that splice variants increase the functional diversity of proteins. Furthermore, AS is coupled to transcript stability and translation through nonsense-mediated decay and microRNA-mediated gene regulation. Widespread changes in AS in response to developmental cues and stresses suggest a role for regulated splicing in plant development and stress responses. Here, we review recent progress in uncovering the extent and complexity of the AS landscape in plants, its regulation, and the roles of AS in gene regulation. The prevalence of AS in plants has raised many new questions that require additional studies. New tools based on recent technological advances are allowing genome-wide analysis of RNA elements in transcripts and of chromatin modifications that regulate AS. Application of these tools in plants will provide significant new insights into AS regulation and crosstalk between AS and other layers of gene regulation.
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Affiliation(s)
- Anireddy S.N. Reddy
- Department of Biology, Program in Molecular Plant Biology, Program in Cell and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523
- Address correspondence to
| | - Yamile Marquez
- Max F. Perutz Laboratories, Medical University of Vienna, Vienna A-1030, Austria
| | - Maria Kalyna
- Max F. Perutz Laboratories, Medical University of Vienna, Vienna A-1030, Austria
| | - Andrea Barta
- Max F. Perutz Laboratories, Medical University of Vienna, Vienna A-1030, Austria
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33
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Hosseini P, Ovcharenko I, Matthews BF. Using an ensemble of statistical metrics to quantify large sets of plant transcription factor binding sites. PLANT METHODS 2013; 9:12. [PMID: 23578135 PMCID: PMC3639912 DOI: 10.1186/1746-4811-9-12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 03/28/2013] [Indexed: 05/07/2023]
Abstract
BACKGROUND From initial seed germination through reproduction, plants continuously reprogram their transcriptional repertoire to facilitate growth and development. This dynamic is mediated by a diverse but inextricably-linked catalog of regulatory proteins called transcription factors (TFs). Statistically quantifying TF binding site (TFBS) abundance in promoters of differentially expressed genes can be used to identify binding site patterns in promoters that are closely related to stress-response. Output from today's transcriptomic assays necessitates statistically-oriented software to handle large promoter-sequence sets in a computationally tractable fashion. RESULTS We present Marina, an open-source software for identifying over-represented TFBSs from amongst large sets of promoter sequences, using an ensemble of 7 statistical metrics and binding-site profiles. Through software comparison, we show that Marina can identify considerably more over-represented plant TFBSs compared to a popular software alternative. CONCLUSIONS Marina was used to identify over-represented TFBSs in a two time-point RNA-Seq study exploring the transcriptomic interplay between soybean (Glycine max) and soybean rust (Phakopsora pachyrhizi). Marina identified numerous abundant TFBSs recognized by transcription factors that are associated with defense-response such as WRKY, HY5 and MYB2. Comparing results from Marina to that of a popular software alternative suggests that regardless of the number of promoter-sequences, Marina is able to identify significantly more over-represented TFBSs.
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Affiliation(s)
- Parsa Hosseini
- Department of Bioinformatics and Computational Biology, George Mason University, Manassas, Virginia, USA
- Computational Biology Branch, National Center for Biotechnology Information, National Institutes of Health, Bethesda, Maryland, USA
- Soybean Genomics and Improvement Laboratory, United States Department of Agriculture, Beltsville, Maryland, USA
| | - Ivan Ovcharenko
- Computational Biology Branch, National Center for Biotechnology Information, National Institutes of Health, Bethesda, Maryland, USA
| | - Benjamin F Matthews
- Soybean Genomics and Improvement Laboratory, United States Department of Agriculture, Beltsville, Maryland, USA
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Szcześniak MW, Kabza M, Pokrzywa R, Gudyś A, Makałowska I. ERISdb: A Database of Plant Splice Sites and Splicing Signals. ACTA ACUST UNITED AC 2013; 54:e10. [DOI: 10.1093/pcp/pct001] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Thomas J, Palusa SG, Prasad KVSK, Ali GS, Surabhi GK, Ben-Hur A, Abdel-Ghany SE, Reddy ASN. Identification of an intronic splicing regulatory element involved in auto-regulation of alternative splicing of SCL33 pre-mRNA. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2012; 72:935-46. [PMID: 22913769 DOI: 10.1111/tpj.12004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
In Arabidopsis, pre-mRNAs of serine/arginine-rich (SR) proteins undergo extensive alternative splicing (AS). However, little is known about the cis-elements and trans-acting proteins involved in regulating AS. Using a splicing reporter (GFP-intron-GFP), consisting of the GFP coding sequence interrupted by an alternatively spliced intron of SCL33, we investigated whether cis-elements within this intron are sufficient for AS, and which SR proteins are necessary for regulated AS. Expression of the splicing reporter in protoplasts faithfully produced all splice variants from the intron, suggesting that cis-elements required for AS reside within the intron. To determine which SR proteins are responsible for AS, the splicing pattern of the GFP-intron-GFP reporter was investigated in protoplasts of three single and three double mutants of SR genes. These analyses revealed that SCL33 and a closely related paralog, SCL30a, are functionally redundant in generating specific splice variants from this intron. Furthermore, SCL33 protein bound to a conserved sequence in this intron, indicating auto-regulation of AS. Mutations in four GAAG repeats within the conserved region impaired generation of the same splice variants that are affected in the scl33 scl30a double mutant. In conclusion, we have identified the first intronic cis-element involved in AS of a plant SR gene, and elucidated a mechanism for auto-regulation of AS of this intron.
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Affiliation(s)
- Julie Thomas
- Department of Biology, Program in Molecular Plant Biology, Program in Cell and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USADepartment of Computer Science and Program in Molecular Plant Biology, Colorado State University, Fort Collins, CO 80523, USA
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Streitner C, Köster T, Simpson CG, Shaw P, Danisman S, Brown JWS, Staiger D. An hnRNP-like RNA-binding protein affects alternative splicing by in vivo interaction with transcripts in Arabidopsis thaliana. Nucleic Acids Res 2012; 40:11240-55. [PMID: 23042250 PMCID: PMC3526319 DOI: 10.1093/nar/gks873] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Alternative splicing (AS) of pre-mRNAs is an important regulatory mechanism shaping the transcriptome. In plants, only few RNA-binding proteins are known to affect AS. Here, we show that the glycine-rich RNA-binding protein AtGRP7 influences AS in Arabidopsis thaliana. Using a high-resolution RT–PCR-based AS panel, we found significant changes in the ratios of AS isoforms for 59 of 288 analyzed AS events upon ectopic AtGRP7 expression. In particular, AtGRP7 affected the choice of alternative 5′ splice sites preferentially. About half of the events are also influenced by the paralog AtGRP8, indicating that AtGRP7 and AtGRP8 share a network of downstream targets. For 10 events, the AS patterns were altered in opposite directions in plants with elevated AtGRP7 level or lacking AtGRP7. Importantly, RNA immunoprecipitation from plant extracts showed that several transcripts are bound by AtGRP7 in vivo and indeed represent direct targets. Furthermore, the effect of AtGRP7 on these AS events was abrogated by mutation of a single arginine that is required for its RNA-binding activity. This indicates that AtGRP7 impacts AS of these transcripts via direct interaction. As several of the AS events are also controlled by other splicing regulators, our data begin to provide insights into an AS network in Arabidopsis.
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Reddy ASN, Rogers MF, Richardson DN, Hamilton M, Ben-Hur A. Deciphering the plant splicing code: experimental and computational approaches for predicting alternative splicing and splicing regulatory elements. FRONTIERS IN PLANT SCIENCE 2012; 3:18. [PMID: 22645572 PMCID: PMC3355732 DOI: 10.3389/fpls.2012.00018] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2011] [Accepted: 01/18/2012] [Indexed: 05/20/2023]
Abstract
Extensive alternative splicing (AS) of precursor mRNAs (pre-mRNAs) in multicellular eukaryotes increases the protein-coding capacity of a genome and allows novel ways to regulate gene expression. In flowering plants, up to 48% of intron-containing genes exhibit AS. However, the full extent of AS in plants is not yet known, as only a few high-throughput RNA-Seq studies have been performed. As the cost of obtaining RNA-Seq reads continues to fall, it is anticipated that huge amounts of plant sequence data will accumulate and help in obtaining a more complete picture of AS in plants. Although it is not an onerous task to obtain hundreds of millions of reads using high-throughput sequencing technologies, computational tools to accurately predict and visualize AS are still being developed and refined. This review will discuss the tools to predict and visualize transcriptome-wide AS in plants using short-reads and highlight their limitations. Comparative studies of AS events between plants and animals have revealed that there are major differences in the most prevalent types of AS events, suggesting that plants and animals differ in the way they recognize exons and introns. Extensive studies have been performed in animals to identify cis-elements involved in regulating AS, especially in exon skipping. However, few such studies have been carried out in plants. Here, we review the current state of research on splicing regulatory elements (SREs) and briefly discuss emerging experimental and computational tools to identify cis-elements involved in regulation of AS in plants. The availability of curated alternative splice forms in plants makes it possible to use computational tools to predict SREs involved in AS regulation, which can then be verified experimentally. Such studies will permit identification of plant-specific features involved in AS regulation and contribute to deciphering the splicing code in plants.
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Affiliation(s)
- Anireddy S. N. Reddy
- Program in Molecular Plant Biology, Department of Biology, Colorado State UniversityFort Collins, CO, USA
| | - Mark F. Rogers
- Department of Computer Science, Colorado State UniversityFort Collins, CO, USA
| | - Dale N. Richardson
- Centro de Investigação em Biodiversidade e Recursos Genéticos, University of PortoVairão, Portugal
| | - Michael Hamilton
- Department of Computer Science, Colorado State UniversityFort Collins, CO, USA
| | - Asa Ben-Hur
- Department of Computer Science, Colorado State UniversityFort Collins, CO, USA
- Program in Molecular Plant Biology, Colorado State UniversityFort Collins, CO, USA
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38
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Brooks AN, Aspden JL, Podgornaia AI, Rio DC, Brenner SE. Identification and experimental validation of splicing regulatory elements in Drosophila melanogaster reveals functionally conserved splicing enhancers in metazoans. RNA (NEW YORK, N.Y.) 2011; 17:1884-94. [PMID: 21865603 PMCID: PMC3185920 DOI: 10.1261/rna.2696311] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Accepted: 07/08/2011] [Indexed: 05/22/2023]
Abstract
RNA sequence elements involved in the regulation of pre-mRNA splicing have previously been identified in vertebrate genomes by computational methods. Here, we apply such approaches to predict splicing regulatory elements in Drosophila melanogaster and compare them with elements previously found in the human, mouse, and pufferfish genomes. We identified 99 putative exonic splicing enhancers (ESEs) and 231 putative intronic splicing enhancers (ISEs) enriched near weak 5' and 3' splice sites of constitutively spliced introns, distinguishing between those found near short and long introns. We found that a significant proportion (58%) of fly enhancer sequences were previously reported in at least one of the vertebrates. Furthermore, 20% of putative fly ESEs were previously identified as ESEs in human, mouse, and pufferfish; while only two fly ISEs, CTCTCT and TTATAA, were identified as ISEs in all three vertebrate species. Several putative enhancer sequences are similar to characterized binding-site motifs for Drosophila and mammalian splicing regulators. To provide additional evidence for the function of putative ISEs, we separately identified 298 intronic hexamers significantly enriched within sequences phylogenetically conserved among 15 insect species. We found that 73 putative ISEs were among those enriched in conserved regions of the D. melanogaster genome. The functions of nine enhancer sequences were verified in a heterologous splicing reporter, demonstrating that these sequences are sufficient to enhance splicing in vivo. Taken together, these data identify a set of predicted positive-acting splicing regulatory motifs in the Drosophila genome and reveal regulatory sequences that are present in distant metazoan genomes.
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Affiliation(s)
- Angela N. Brooks
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, USA
| | - Julie L. Aspden
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, USA
- Center for Integrative Genomics, University of California, Berkeley, California 94720, USA
| | - Anna I. Podgornaia
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, USA
| | - Donald C. Rio
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, USA
- Center for Integrative Genomics, University of California, Berkeley, California 94720, USA
| | - Steven E. Brenner
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, USA
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, USA
- Corresponding author.E-mail .
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Reddy ASN, Shad Ali G. Plant serine/arginine-rich proteins: roles in precursor messenger RNA splicing, plant development, and stress responses. WILEY INTERDISCIPLINARY REVIEWS-RNA 2011; 2:875-89. [PMID: 21766458 DOI: 10.1002/wrna.98] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Global analyses of splicing of precursor messenger RNAs (pre-mRNAs) have revealed that alternative splicing (AS) is highly pervasive in plants. Despite the widespread occurrence of AS in plants, the mechanisms that control splicing and the roles of splice variants generated from a gene are poorly understood. Studies on plant serine/arginine-rich (SR) proteins, a family of highly conserved proteins, suggest their role in both constitutive splicing and AS of pre-mRNAs. SR proteins have a characteristic domain structure consisting of one or two RNA recognition motifs at the N-terminus and a C-terminal RS domain rich in arginine/serine dipeptides. Plants have many more SR proteins compared to animals including several plant-specific subfamilies. Pre-mRNAs of plant SR proteins are extensively alternatively spliced to increase the transcript complexity by about six-fold. Some of this AS is controlled in a tissue- and development-specific manner. Furthermore, AS of SR pre-mRNAs is altered by various stresses, raising the possibility of rapid reprogramming of the whole transcriptome by external signals through regulation of the splicing of these master regulators of splicing. Most SR splice variants contain a premature termination codon and are degraded by up-frameshift 3 (UPF3)-mediated nonsense-mediated decay (NMD), suggesting a link between NMD and regulation of expression of the functional transcripts of SR proteins. Limited functional studies with plant SRs suggest key roles in growth and development and plant responses to the environment. Here, we discuss the current status of research on plant SRs and some promising approaches to address many unanswered questions about plant SRs.
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Affiliation(s)
- Anireddy S N Reddy
- Department of Biology, Program in Molecular Plant Biology, Program in Cell and Molecular Biology, Colorado State University, Fort Collins, CO, USA.
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Ahmed F, Benedito VA, Zhao PX. Mining Functional Elements in Messenger RNAs: Overview, Challenges, and Perspectives. FRONTIERS IN PLANT SCIENCE 2011; 2:84. [PMID: 22639614 PMCID: PMC3355573 DOI: 10.3389/fpls.2011.00084] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Accepted: 11/03/2011] [Indexed: 05/03/2023]
Abstract
Eukaryotic messenger RNA (mRNA) contains not only protein-coding regions but also a plethora of functional cis-elements that influence or coordinate a number of regulatory aspects of gene expression, such as mRNA stability, splicing forms, and translation rates. Understanding the rules that apply to each of these element types (e.g., whether the element is defined by primary or higher-order structure) allows for the discovery of novel mechanisms of gene expression as well as the design of transcripts with controlled expression. Bioinformatics plays a major role in creating databases and finding non-evident patterns governing each type of eukaryotic functional element. Much of what we currently know about mRNA regulatory elements in eukaryotes is derived from microorganism and animal systems, with the particularities of plant systems lagging behind. In this review, we provide a general introduction to the most well-known eukaryotic mRNA regulatory motifs (splicing regulatory elements, internal ribosome entry sites, iron-responsive elements, AU-rich elements, zipcodes, and polyadenylation signals) and describe available bioinformatics resources (databases and analysis tools) to analyze eukaryotic transcripts in search of functional elements, focusing on recent trends in bioinformatics methods and tool development. We also discuss future directions in the development of better computational tools based upon current knowledge of these functional elements. Improved computational tools would advance our understanding of the processes underlying gene regulations. We encourage plant bioinformaticians to turn their attention to this subject to help identify novel mechanisms of gene expression regulation using RNA motifs that have potentially evolved or diverged in plant species.
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Affiliation(s)
- Firoz Ahmed
- Bioinformatics Laboratory, Plant Biology Division, Samuel Roberts Noble FoundationArdmore, OK, USA
| | - Vagner A. Benedito
- Genetics and Developmental Biology, Plant and Soil Sciences Division, West Virginia UniversityMorgantown, WV, USA
| | - Patrick Xuechun Zhao
- Bioinformatics Laboratory, Plant Biology Division, Samuel Roberts Noble FoundationArdmore, OK, USA
- *Correspondence: Patrick Xuechun Zhao, Bioinformatics Laboratory, Plant Biology Division, Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK 73401, USA e-mail:
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Experimentally increased codon bias in the Drosophila Adh gene leads to an increase in larval, but not adult, alcohol dehydrogenase activity. Genetics 2009; 184:547-55. [PMID: 19966063 DOI: 10.1534/genetics.109.111294] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Although most amino acids can be encoded by more than one codon, the synonymous codons are not used with equal frequency. This phenomenon is known as codon bias and appears to be a universal feature of genomes. The translational selection hypothesis posits that the use of optimal codons, which match the most abundant species of isoaccepting tRNAs, results in increased translational efficiency and accuracy. Previous work demonstrated that the experimental reduction of codon bias in the Drosophila alcohol dehydrogenase (Adh) gene led to a significant decrease in ADH protein expression. In this study we performed the converse experiment: we replaced seven suboptimal leucine codons that occur naturally in the Drosophila melanogaster Adh gene with the optimal codon. We then compared the in vivo ADH activities imparted by the wild-type and mutant alleles. The introduction of optimal leucine codons led to an increase in ADH activity in third-instar larvae. In adult flies, however, the introduction of optimal codons led to a decrease in ADH activity. There is no evidence that other selectively constrained features of the Adh gene, or its rate of transcription, were altered by the synonymous replacements. These results are consistent with translational selection for codon bias being stronger in the larval stage and suggest that there may be a selective conflict over optimal codon usage between different developmental stages.
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SpliceIT: a hybrid method for splice signal identification based on probabilistic and biological inference. J Biomed Inform 2009; 43:208-17. [PMID: 19800027 DOI: 10.1016/j.jbi.2009.09.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2008] [Revised: 08/25/2009] [Accepted: 09/21/2009] [Indexed: 11/23/2022]
Abstract
Splice sites define the boundaries of exonic regions and dictate protein synthesis and function. The splicing mechanism involves complex interactions among positional and compositional features of different lengths. Computational modeling of the underlying constructive information is especially challenging, in order to decipher splicing-inducing elements and alternative splicing factors. SpliceIT (Splice Identification Technique) introduces a hybrid method for splice site prediction that couples probabilistic modeling with discriminative computational or experimental features inferred from published studies in two subsequent classification steps. The first step is undertaken by a Gaussian support vector machine (SVM) trained on the probabilistic profile that is extracted using two alternative position-dependent feature selection methods. In the second step, the extracted predictions are combined with known species-specific regulatory elements, in order to induce a tree-based modeling. The performance evaluation on human and Arabidopsis thaliana splice site datasets shows that SpliceIT is highly accurate compared to current state-of-the-art predictors in terms of the maximum sensitivity, specificity tradeoff without compromising space complexity and in a time-effective way. The source code and supplementary material are available at: http://www.med.auth.gr/research/spliceit/.
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Takahashi A. Effect of exonic splicing regulation on synonymous codon usage in alternatively spliced exons of Dscam. BMC Evol Biol 2009; 9:214. [PMID: 19709440 PMCID: PMC2741454 DOI: 10.1186/1471-2148-9-214] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2008] [Accepted: 08/27/2009] [Indexed: 12/31/2022] Open
Abstract
Background Synonymous codon usage is typically biased towards translationally superior codons in many organisms. In Drosophila, genomic data indicates that translationally optimal codons and splice optimal codons are mostly mutually exclusive, and adaptation to translational efficiency is reduced in the intron-exon boundary regions where potential exonic splicing enhancers (ESEs) reside. In contrast to genomic scale analyses on large datasets, a refined study on a well-controlled set of samples can be effective in demonstrating the effects of particular splice-related factors. Down syndrome cell adhesion molecule (Dscam) has the largest number of alternatively spliced exons (ASEs) known to date, and the splicing frequency of each ASE is accessible from the relative abundance of the transcript. Thus, these ASEs comprise a unique model system for studying the effect of splicing regulation on synonymous codon usage. Results Codon Bias Indices (CBI) in the 3' boundary regions were reduced compared to the rest of the exonic regions among 48 and 33 ASEs of exon 6 and 9 clusters, respectively. These regional differences in CBI were affected by splicing frequency and distance from adjacent exons. Synonymous divergence levels between the 3' boundary region and the remaining exonic region of exon 6 ASEs were similar. Additionally, another sensitive comparison of paralogous exonic regions in recently retrotransposed processed genes and their parental genes revealed that, in the former, the differences in CBI between what were formerly the central regions and the boundary regions gradually became smaller over time. Conclusion Analyses of the multiple ASEs of Dscam allowed direct tests of the effect of splice-related factors on synonymous codon usage and provided clear evidence that synonymous codon usage bias is restricted by exonic splicing signals near the intron-exon boundary. A similar synonymous divergence level between the different exonic regions suggests that the intensity of splice-related selection is generally weak and comparable to that of translational selection. Finally, the leveling off of differences in codon bias over time in retrotransposed genes meets the direct prediction of the tradeoff model that invokes conflict between translational superiority and splicing regulation, and strengthens the conclusions obtained from Dscam.
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Affiliation(s)
- Aya Takahashi
- Division of Population Genetics, National Institute of Genetics, Mishima 411-8540, Japan.
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Mersch B, Gepperth A, Suhai S, Hotz-Wagenblatt A. Automatic detection of exonic splicing enhancers (ESEs) using SVMs. BMC Bioinformatics 2008; 9:369. [PMID: 18783607 PMCID: PMC2567995 DOI: 10.1186/1471-2105-9-369] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2007] [Accepted: 09/10/2008] [Indexed: 11/10/2022] Open
Abstract
Background Exonic splicing enhancers (ESEs) activate nearby splice sites and promote the inclusion (vs. exclusion) of exons in which they reside, while being a binding site for SR proteins. To study the impact of ESEs on alternative splicing it would be useful to have a possibility to detect them in exons. Identifying SR protein-binding sites in human DNA sequences by machine learning techniques is a formidable task, since the exon sequences are also constrained by their functional role in coding for proteins. Results The choice of training examples needed for machine learning approaches is difficult since there are only few exact locations of human ESEs described in the literature which could be considered as positive examples. Additionally, it is unclear which sequences are suitable as negative examples. Therefore, we developed a motif-oriented data-extraction method that extracts exon sequences around experimentally or theoretically determined ESE patterns. Positive examples are restricted by heuristics based on known properties of ESEs, e.g. location in the vicinity of a splice site, whereas negative examples are taken in the same way from the middle of long exons. We show that a suitably chosen SVM using optimized sequence kernels (e.g., combined oligo kernel) can extract meaningful properties from these training examples. Once the classifier is trained, every potential ESE sequence can be passed to the SVM for verification. Using SVMs with the combined oligo kernel yields a high accuracy of about 90 percent and well interpretable parameters. Conclusion The motif-oriented data-extraction method seems to produce consistent training and test data leading to good classification rates and thus allows verification of potential ESE motifs. The best results were obtained using an SVM with the combined oligo kernel, while oligo kernels with oligomers of a certain length could be used to extract relevant features.
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Affiliation(s)
- Britta Mersch
- Department of Molecular Biophysics, German Cancer Research Center DKFZ, Im Neuenheimer Feld 580, Heidelberg, Germany.
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Abstract
The spliceosome is a large nuclear structure consisting of dynamically interacting RNAs and proteins. This chapter briefly reviews some of the known components and their interactions. Large-scale proteomics and gene expression studies may be required to unravel the many intricate mechanisms involved in splice site recognition and selection.
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Abstract
A substantial fraction (approximately 30%) of plant genes is alternatively spliced, but how alternative splicing is regulated remains unknown. Many plant genes undergo alternative splicing in response to a variety of stresses. Large-scale computational analyses and experimental approaches focused on select genes are beginning to reveal that alternative splicing constitutes an integral part of gene regulation in stress responses. Based on the studies discussed in this chapter, it appears that alternative splicing generates transcriptome/proteome complexity that is likely to be important for stress adaptation. However, the signaling pathways that relay stress conditions to splicing machinery and if and how the alternative spliced products confer adaptive advantages to plants are poorly understood.
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DNA codes and information: formal structures and relational causes. Acta Biotheor 2008; 56:205-32. [PMID: 18465197 DOI: 10.1007/s10441-008-9049-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2007] [Accepted: 03/09/2008] [Indexed: 02/03/2023]
Abstract
Recently the terms "codes" and "information" as used in the context of molecular biology have been the subject of much discussion. Here I propose that a variety of structural realism can assist us in rethinking the concepts of DNA codes and information apart from semantic criteria. Using the genetic code as a theoretical backdrop, a necessary distinction is made between codes qua symbolic representations and information qua structure that accords with data. Structural attractors are also shown to be entailed by the mapping relation that any DNA code is a part of (as the domain). In this framework, these attractors are higher-order informational structures that obviate any "DNA-centric" reductionism. In addition to the implications that are discussed, this approach validates the array of coding systems now recognized in molecular biology.
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Barbazuk WB, Fu Y, McGinnis KM. Genome-wide analyses of alternative splicing in plants: opportunities and challenges. Genome Res 2008; 18:1381-92. [PMID: 18669480 DOI: 10.1101/gr.053678.106] [Citation(s) in RCA: 252] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Alternative splicing (AS) creates multiple mRNA transcripts from a single gene. While AS is known to contribute to gene regulation and proteome diversity in animals, the study of its importance in plants is in its early stages. However, recently available plant genome and transcript sequence data sets are enabling a global analysis of AS in many plant species. Results of genome analysis have revealed differences between animals and plants in the frequency of alternative splicing. The proportion of plant genes that have one or more alternative transcript isoforms is approximately 20%, indicating that AS in plants is not rare, although this rate is approximately one-third of that observed in human. The majority of plant AS events have not been functionally characterized, but evidence suggests that AS participates in important plant functions, including stress response, and may impact domestication and trait selection. The increasing availability of plant genome sequence data will enable larger comparative analyses that will identify functionally important plant AS events based on their evolutionary conservation, determine the influence of genome duplication on the evolution of AS, and discover plant-specific cis-elements that regulate AS. This review summarizes recent analyses of AS in plants, discusses the importance of further analysis, and suggests directions for future efforts.
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Affiliation(s)
- W Brad Barbazuk
- Donald Danforth Plant Science Center, St. Louis, Missouri 63132, USA.
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Bechtel JM, Rajesh P, Ilikchyan I, Deng Y, Mishra PK, Wang Q, Wu X, Afonin KA, Grose WE, Wang Y, Khuder S, Fedorov A. Calculation of splicing potential from the Alternative Splicing Mutation Database. BMC Res Notes 2008; 1:4. [PMID: 18611287 PMCID: PMC2518266 DOI: 10.1186/1756-0500-1-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2008] [Accepted: 02/26/2008] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND The Alternative Splicing Mutation Database (ASMD) presents a collection of all known mutations inside human exons which affect splicing enhancers and silencers and cause changes in the alternative splicing pattern of the corresponding genes. FINDINGS An algorithm was developed to derive a Splicing Potential (SP) table from the ASMD information. This table characterizes the influence of each oligonucleotide on the splicing effectiveness of the exon containing it. If the SP value for an oligonucleotide is positive, it promotes exon retention, while negative SP values mean the sequence favors exon skipping. The merit of the SP approach is the ability to separate splicing signals from a wide range of sequence motifs enriched in exonic sequences that are attributed to protein-coding properties and/or translation efficiency. Due to its direct derivation from observed splice site selection, SP has an advantage over other computational approaches for predicting alternative splicing. CONCLUSION We show that a vast majority of known exonic splicing enhancers have highly positive cumulative SP values, while known splicing silencers have core motifs with strongly negative cumulative SP values. Our approach allows for computation of the cumulative SP value of any sequence segment and, thus, gives researchers the ability to measure the possible contribution of any sequence to the pattern of splicing.
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Affiliation(s)
- Jason M Bechtel
- Program in Bioinformatics and Proteomics/Genomics, University of Toledo Health Science Campus, Toledo, Ohio 43614, USA.
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Bechtel JM, Rajesh P, Ilikchyan I, Deng Y, Mishra PK, Wang Q, Wu X, Afonin KA, Grose WE, Wang Y, Khuder S, Fedorov A. The Alternative Splicing Mutation Database: a hub for investigations of alternative splicing using mutational evidence. BMC Res Notes 2008; 1:3. [PMID: 18611286 PMCID: PMC2518265 DOI: 10.1186/1756-0500-1-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2008] [Accepted: 02/26/2008] [Indexed: 11/22/2022] Open
Abstract
Background Some mutations in the internal regions of exons occur within splicing enhancers and silencers, influencing the pattern of alternative splicing in the corresponding genes. To understand how these sequence changes affect splicing, we created a database of these mutations. Findings The Alternative Splicing Mutation Database (ASMD) serves as a repository for all exonic mutations not associated with splicing junctions that measurably change the pattern of alternative splicing. In this initial published release (version 1.2), only human sequences are present, but the ASMD will grow to include other organisms, (see Availability and requirements section for the ASMD web address). This relational database allows users to investigate connections between mutations and features of the surrounding sequences, including flanking sequences, RNA secondary structures and strengths of splice junctions. Splicing effects of the mutations are quantified by the relative presence of alternative mRNA isoforms with and without a given mutation. This measure is further categorized by the accuracy of the experimental methods employed. The database currently contains 170 mutations in 66 exons, yet these numbers increase regularly. We developed an algorithm to derive a table of oligonucleotide Splicing Potential (SP) values from the ASMD dataset. We present the SP concept and tools in detail in our corresponding article. Conclusion The current data set demonstrates that mutations affecting splicing are located throughout exons and might be enriched within local RNA secondary structures. Exons from the ASMD have below average splicing junction strength scores, but the difference is small and is judged not to be significant.
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Affiliation(s)
- Jason M Bechtel
- Program in Bioinformatics and Proteomics/Genomics, University of Toledo Health Science Campus, Toledo, Ohio 43614, USA.
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