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Wang J, Ma X, Hu Y, Feng G, Guo C, Zhang X, Ma H. Regulation of micro- and small-exon retention and other splicing processes by GRP20 for flower development. NATURE PLANTS 2024; 10:66-85. [PMID: 38195906 PMCID: PMC10808074 DOI: 10.1038/s41477-023-01605-8] [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: 11/11/2022] [Accepted: 11/29/2023] [Indexed: 01/11/2024]
Abstract
Pre-mRNA splicing is crucial for gene expression and depends on the spliceosome and splicing factors. Plant exons have an average size of ~180 nucleotides and typically contain motifs for interactions with spliceosome and splicing factors. Micro exons (<51 nucleotides) are found widely in eukaryotes and in genes for plant development and environmental responses. However, little is known about transcript-specific regulation of splicing in plants and about the regulators for micro exon splicing. Here we report that glycine-rich protein 20 (GRP20) is an RNA-binding protein and required for splicing of ~2,100 genes including those functioning in flower development and/or environmental responses. Specifically, GRP20 is required for micro-exon retention in transcripts of floral homeotic genes; these micro exons are conserved across angiosperms. GRP20 is also important for small-exon (51-100 nucleotides) splicing. In addition, GRP20 is required for flower development. Furthermore, GRP20 binds to poly-purine motifs in micro and small exons and a spliceosome component; both RNA binding and spliceosome interaction are important for flower development and micro-exon retention. Our results provide new insights into the mechanisms of micro-exon retention in flower development.
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Affiliation(s)
- Jun Wang
- Department of Biology, Eberly College of Science, Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, USA
| | - Xinwei Ma
- Department of Biology, Eberly College of Science, Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, USA
| | - Yi Hu
- Department of Biology, Eberly College of Science, Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, USA
| | - Guanhua Feng
- Department of Biology, Eberly College of Science, Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, USA
| | - Chunce Guo
- Jiangxi Provincial Key Laboratory for Bamboo Germplasm Resources and Utilization, Forestry College, Jiangxi Agricultural University, Nanchang, China
| | - Xin Zhang
- Department of Chemistry and Department of Biochemistry and Molecular Biology, Eberly College of Science, Pennsylvania State University, University Park, PA, USA
| | - Hong Ma
- Department of Biology, Eberly College of Science, Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, USA.
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2
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Fan T, Zhao YZ, Yang JF, Liu QL, Tian Y, Debatosh D, Liu YG, Zhang J, Chen C, Chen MX, Zhou SM. Phylogenetic comparison and splice site conservation of eukaryotic U1 snRNP-specific U1-70K gene family. Sci Rep 2021; 11:12760. [PMID: 34140531 PMCID: PMC8211703 DOI: 10.1038/s41598-021-91693-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 05/05/2021] [Indexed: 02/05/2023] Open
Abstract
Eukaryotic cells can expand their coding ability by using their splicing machinery, spliceosome, to process precursor mRNA (pre-mRNA) into mature messenger RNA. The mega-macromolecular spliceosome contains multiple subcomplexes, referred to as small nuclear ribonucleoproteins (snRNPs). Among these, U1 snRNP and its central component, U1-70K, are crucial for splice site recognition during early spliceosome assembly. The human U1-70K has been linked to several types of human autoimmune and neurodegenerative diseases. However, its phylogenetic relationship has been seldom reported. To this end, we carried out a systemic analysis of 95 animal U1-70K genes and compare these proteins to their yeast and plant counterparts. Analysis of their gene and protein structures, expression patterns and splicing conservation suggest that animal U1-70Ks are conserved in their molecular function, and may play essential role in cancers and juvenile development. In particular, animal U1-70Ks display unique characteristics of single copy number and a splicing isoform with truncated C-terminal, suggesting the specific role of these U1-70Ks in animal kingdom. In summary, our results provide phylogenetic overview of U1-70K gene family in vertebrates. In silico analyses conducted in this work will act as a reference for future functional studies of this crucial U1 splicing factor in animal kingdom.
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Affiliation(s)
- Tao Fan
- grid.452787.b0000 0004 1806 5224Division of Gastroenterology, Shenzhen Children’s Hospital, Shenzhen, 518038 People’s Republic of China ,grid.440622.60000 0000 9482 4676State Key Laboratory of Crop Biology, College of Life Science, Shandong Agricultural University, Taian, Shandong People’s Republic of China ,grid.10784.3a0000 0004 1937 0482Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, People’s Republic of China
| | - Yu-Zhen Zhao
- grid.452787.b0000 0004 1806 5224Division of Gastroenterology, Shenzhen Children’s Hospital, Shenzhen, 518038 People’s Republic of China
| | - Jing-Fang Yang
- grid.411407.70000 0004 1760 2614Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, Wuhan, 430079 People’s Republic of China
| | - Qin-Lai Liu
- School of Basic Medicine, Shandong First Medical University and Shandong Academy of Medical Sciences, Qingdao, People’s Republic of China
| | - Yuan Tian
- grid.440622.60000 0000 9482 4676State Key Laboratory of Crop Biology, College of Life Science, Shandong Agricultural University, Taian, Shandong People’s Republic of China ,grid.10784.3a0000 0004 1937 0482Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, People’s Republic of China
| | - Das Debatosh
- grid.10784.3a0000 0004 1937 0482Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, People’s Republic of China
| | - Ying-Gao Liu
- grid.440622.60000 0000 9482 4676State Key Laboratory of Crop Biology, College of Life Science, Shandong Agricultural University, Taian, Shandong People’s Republic of China
| | - Jianhua Zhang
- grid.10784.3a0000 0004 1937 0482Department of Biology, Hong Kong Baptist University, and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Chen Chen
- grid.410745.30000 0004 1765 1045Department of Infectious Disease, Nanjing Infectious Disease Center, The Second Hospital of Nanjing, Nanjing University of Chinese Medicine, Nanjing, 210003 People’s Republic of China
| | - Mo-Xian Chen
- grid.452787.b0000 0004 1806 5224Division of Gastroenterology, Shenzhen Children’s Hospital, Shenzhen, 518038 People’s Republic of China
| | - Shao-Ming Zhou
- grid.452787.b0000 0004 1806 5224Division of Gastroenterology, Shenzhen Children’s Hospital, Shenzhen, 518038 People’s Republic of China
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3
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Chen MX, Zhang KL, Gao B, Yang JF, Tian Y, Das D, Fan T, Dai L, Hao GF, Yang GF, Zhang J, Zhu FY, Fang YM. Phylogenetic comparison of 5' splice site determination in central spliceosomal proteins of the U1-70K gene family, in response to developmental cues and stress conditions. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 103:357-378. [PMID: 32133712 DOI: 10.1111/tpj.14735] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 01/22/2020] [Accepted: 02/04/2020] [Indexed: 05/07/2023]
Abstract
Intron-containing genes have the ability to generate multiple transcript isoforms by splicing, thereby greatly expanding the eukaryotic transcriptome and proteome. In eukaryotic cells, precursor mRNA (pre-mRNA) splicing is performed by a mega-macromolecular complex defined as a spliceosome. Among its splicing components, U1 small nuclear ribonucleoprotein (U1 snRNP) is the smallest subcomplex involved in early spliceosome assembly and 5'-splice site recognition. Its central component, named U1-70K, has been extensively characterized in animals and yeast. Very few investigations on U1-70K genes have been conducted in plants, however. To this end, we performed a comprehensive study to systematically identify 115 U1-70K genes from 67 plant species, ranging from algae to angiosperms. Phylogenetic analysis suggested that the expansion of the plant U1-70K gene family was likely to have been driven by whole-genome duplications. Subsequent comparisons of gene structures, protein domains, promoter regions and conserved splicing patterns indicated that plant U1-70Ks are likely to preserve their conserved molecular function across plant lineages and play an important functional role in response to environmental stresses. Furthermore, genetic analysis using T-DNA insertion mutants suggested that Arabidopsis U1-70K may be involved in response to osmotic stress. Our results provide a general overview of this gene family in Viridiplantae and will act as a reference source for future mechanistic studies on this U1 snRNP-specific splicing factor.
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Affiliation(s)
- Mo-Xian Chen
- Co-Innovation Center for Sustainable Forestry in Southern China, College of Biology and the Environment, Nanjing Forestry University, Nanjing, 210037, China
- Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518063, China
- Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, China
| | - Kai-Lu Zhang
- Co-Innovation Center for Sustainable Forestry in Southern China, College of Biology and the Environment, Nanjing Forestry University, Nanjing, 210037, China
- Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, China
| | - Bei Gao
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Jing-Fang Yang
- Key Laboratory of Pesticide & Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, Wuhan, 430079, China
| | - Yuan Tian
- Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, China
| | - Debatosh Das
- Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, China
| | - Tao Fan
- Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, China
| | - Lei Dai
- Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518063, China
| | - Ge-Fei Hao
- Key Laboratory of Pesticide & Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, Wuhan, 430079, China
| | - Guang-Fu Yang
- Key Laboratory of Pesticide & Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, Wuhan, 430079, China
| | - Jianhua Zhang
- Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, China
- Department of Biology, Hong Kong Baptist University, Shatin, Hong Kong
- State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Fu-Yuan Zhu
- Co-Innovation Center for Sustainable Forestry in Southern China, College of Biology and the Environment, Nanjing Forestry University, Nanjing, 210037, China
| | - Yan-Ming Fang
- Co-Innovation Center for Sustainable Forestry in Southern China, College of Biology and the Environment, Nanjing Forestry University, Nanjing, 210037, China
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4
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Morton M, AlTamimi N, Butt H, Reddy ASN, Mahfouz M. Serine/Arginine-rich protein family of splicing regulators: New approaches to study splice isoform functions. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2019; 283:127-134. [PMID: 31128682 DOI: 10.1016/j.plantsci.2019.02.017] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 02/19/2019] [Accepted: 02/23/2019] [Indexed: 05/06/2023]
Abstract
Serine/arginine-rich (SR) proteins are conserved RNA-binding proteins that play major roles in RNA metabolism. They function as molecular adaptors, facilitate spliceosome assembly and modulate constitutive and alternative splicing of pre-mRNAs. Pre-mRNAs encoding SR proteins and many other proteins involved in stress responses are extensively alternatively spliced in response to diverse stresses. Hence, it is proposed that stress-induced changes in splice isoforms contribute to the adaptation of plants to stress responses. However, functions of most SR genes and their splice isoforms in stress responses are not known. Lack of easy and robust tools hindered the progress in this area. Emerging technologies such as CRISPR/Cas9 will facilitate studies of SR function by enabling the generation of single and multiple knock-out mutants of SR subfamily members. Moreover, CRISPR/Cas13 allows targeted manipulation of splice isoforms from SR and other genes in a constitutive or tissue-specific manner to evaluate functions of individual splice variants. Identification of the in vivo targets of SR proteins and their splice variants using the recently developed TRIBE (Targets of RNA-binding proteins Identified By Editing) and other methods will help unravel their mode of action and splicing regulatory elements under various conditions. These new approaches are expected to provide significant new insights into the roles of SRs and splice isoforms in plants adaptation to diverse stresses.
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Affiliation(s)
- Mitchell Morton
- Division of Biological Sciences, 4700 King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
| | - Nadia AlTamimi
- Division of Biological Sciences, 4700 King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
| | - Haroon Butt
- Laboratory for Genome Engineering, Division of Biological Sciences, 4700 King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
| | - Anireddy S N Reddy
- Department of Biology, Program in Cell and Molecular Biology, Colorado State University, Fort Collins, CO, USA
| | - Magdy Mahfouz
- Division of Biological Sciences, 4700 King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia; Laboratory for Genome Engineering, Division of Biological Sciences, 4700 King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia.
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5
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Differential pre-mRNA Splicing Alters the Transcript Diversity of Helitrons Between the Maize Inbred Lines. G3-GENES GENOMES GENETICS 2015; 5:1703-11. [PMID: 26070844 PMCID: PMC4528327 DOI: 10.1534/g3.115.018630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The propensity to capture and mobilize gene fragments by the highly abundant Helitron family of transposable elements likely impacts the evolution of genes in Zea mays. These elements provide a substrate for natural selection by giving birth to chimeric transcripts by intertwining exons of disparate genes. They also capture flanking exons by read-through transcription. Here, we describe the expression of selected Helitrons in different maize inbred lines. We recently reported that these Helitrons produce multiple isoforms of transcripts in inbred B73 via alternative splicing. Despite sharing high degrees of sequence similarity, the splicing profile of Helitrons differed among various maize inbred lines. The comparison of Helitron sequences identified unique polymorphisms in inbred B73, which potentially give rise to the alternatively spliced sites utilized by transcript isoforms. Some alterations in splicing, however, do not have obvious explanations. These observations not only add another level to the creation of transcript diversity by Helitrons among inbred lines but also provide novel insights into the cis-acting elements governing splice-site selection during pre-mRNA processing.
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6
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Rauch HB, Patrick TL, Klusman KM, Battistuzzi FU, Mei W, Brendel VP, Lal SK. Discovery and expression analysis of alternative splicing events conserved among plant SR proteins. Mol Biol Evol 2013; 31:605-13. [PMID: 24356560 DOI: 10.1093/molbev/mst238] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The high frequency of alternative splicing among the serine/arginine-rich (SR) family of proteins in plants has been linked to important roles in gene regulation during development and in response to environmental stress. In this article, we have searched and manually annotated all the SR proteins in the genomes of maize and sorghum. The experimental validation of gene structure by reverse transcription-polymerase chain reaction (RT-PCR) analysis revealed, with few exceptions, that SR genes produced multiple isoforms of transcripts by alternative splicing. Despite sharing high structural similarity and conserved positions of the introns, the profile of alternative splicing diverged significantly between maize and sorghum for the vast majority of SR genes. These include many transcript isoforms discovered by RT-PCR and not represented in extant expressed sequence tag (EST) collection. However, we report the occurrence of various maize and sorghum SR mRNA isoforms that display evolutionary conservation of splicing events with their homologous SR genes in Arabidopsis and moss. Our data also indicate an important role of both 5' and 3' untranslated regions in the regulation of SR gene expression. These observations have potentially important implications for the processes of evolution and adaptation of plants to land.
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7
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Llaca V, Gepts P. Pulsed-field gel electrophoresis analysis of the phaseolin locus region in Phaseolus vulgaris. Genome 2012; 39:722-9. [PMID: 18469932 DOI: 10.1139/g96-091] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Phaseolin is the major seed storage protein of common bean (Phaseolus vulgaris L.). It is encoded by a small multigene family of 6-9 genes that are clustered in a single complex locus (Phs). We have constructed a long-range restriction map of the phaseolin genomic region, including the Phs locus and two flanking marker loci, D1861 and Bng060. Using a combination of high molecular weight DNA isolation, one- and two-dimensional pulsed-field gel electrophoresis of single and double restriction digests followed by Southern hybridization, and PCR analysis of individual fragments, we found that: (i) the maximum size of the Phs locus is 190 kb, (ii) the Phs locus may have increased in size during the evolution of P. vulgaris, (iii) the genomic region marked by D1861-Phs-Bng060 spans 5 cM, which corresponds to a maximum of 1.9 Mb, and (iv) the Phs locus could be oriented with respect to the two adjacent markers. Further progress in determining the gene arrangement in the Phs locus will require cloning and analysis of large DNA fragments containing phaseolin genes via BAC libraries. Key words : multigene family, physical distance, genome mapping, seed protein.
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8
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Duque P. A role for SR proteins in plant stress responses. PLANT SIGNALING & BEHAVIOR 2011; 6:49-54. [PMID: 21258207 PMCID: PMC3122005 DOI: 10.4161/psb.6.1.14063] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2010] [Accepted: 10/31/2010] [Indexed: 05/19/2023]
Abstract
Members of the SR (serine/arginine-rich) protein gene family are key players in the regulation of alternative splicing, an important means of generating proteome diversity and regulating gene expression. In plants, marked changes in alternative splicing are induced by a wide variety of abiotic stresses, suggesting a role for this highly versatile gene regulation mechanism in the response to environmental cues. In support of this notion, the expression of plant SR proteins is stress-regulated at multiple levels, with environmental signals controlling their own alternative splicing patterns, phosphorylation status and subcellular distribution. Most importantly, functional links between these RNA-binding proteins and plant stress tolerance are beginning to emerge, including a role in the regulation of abscisic acid (ABA) signaling. Future identification of the physiological mRNA targets of plant SR proteins holds much promise for the elucidation of the molecular mechanisms underlying their role in the response to abiotic stress.
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Affiliation(s)
- Paula Duque
- Instituto Gulbenkian de Ciência, Oeiras, Portugal.
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9
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Franco OL, Pelegrini PB, Gomes CPC, Souza A, Costa FT, Domont G, Quirino BF, Eira MT, Mehta A. Proteomic evaluation of coffee zygotic embryos in two different stages of seed development. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2009; 47:1046-1050. [PMID: 19775900 DOI: 10.1016/j.plaphy.2009.08.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2009] [Revised: 07/07/2009] [Accepted: 08/31/2009] [Indexed: 05/28/2023]
Abstract
Coffee seed development is accompanied by severe modifications in water soluble proteins, several of these being associated to a specific developmental stage. For this reason, a proteomic approach has been used to describe spatial-temporal proteome modifications in zygotic embryos at different stages of seed development. Embryos from Coffea arabica seeds were harvested in two different developmental stages: stage 1 at 210 days after anthesis and stage 2 at 255 days. Total proteins were extracted and submitted to 2-DE. From these gels, several spots were identified by mass spectrometry including kinases, MYB transcription factor and enzymes involved in metabolic pathways. All proteins identified seem to affect coffee development in different ways, being directly involved in plant growth or used as an intermediate in some metabolic pathway that, indirectly, will influence coffee development. This is the first work using two-dimensional electrophoresis followed by mass spectrometry analyses that evaluates the expression of proteins during coffee zygotic embryos development. Data here reported supply some light over coffee development and could be used in a near future to improve coffee plants' growth and development by molecular strategies.
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Affiliation(s)
- Octavio L Franco
- Centro de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília - DF, Brazil.
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10
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Zhi Q, Wang S, Chai M, Zhang F, Li Q, Li S, Sun M. Transgenic mini-tomato and protection against alcohol-induced gastric injury. J Genet Genomics 2009; 34:756-63. [PMID: 17707220 DOI: 10.1016/s1673-8527(07)60085-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2006] [Accepted: 12/06/2006] [Indexed: 11/26/2022]
Abstract
The epidermal growth factor (EGF) has been shown to promote the proliferation of various types of cells, to maintain the physiological function of the mucosa of the digestive tract, and to promote the healing of the gastric and duodenal ulcers. It has been expressed in many types of bacteria and yeasts. In this article, a bio-reactor was constructed, namely, the human EGF (hEGF) transgenic mini-tomato. On the basis of hEGF gene sequence, a tomato codon preference hEGF gene was chemically synthesized, and it was constructed into the plant expression vector pCAMBIA2300. The transgenic tomato plants containing gene hEGF were obtained through Agrobacterium-mediated transformation. The expression product was determined by radioimmunoassay (RIA) and showed a yield of 3.48 +/- 1.01 ng/g fresh fruits. The intragastric gavage (ig) administration of the rhEGF-containing juice of the transgenic tomato (equivalent to 24 ng rhEGF per mouse a day) for 15 days could significantly protect mice against the alcohol-induced ulceration. The ulcer index, expressed as a degree of the stomach lesion, decreased from 42.20 +/- 18.13 to 16.25 +/- 9.57.
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Affiliation(s)
- Qingwen Zhi
- Institute of Pharmacology and Toxicology, Academy of Military Medical Sciences, Beijing 100850, China
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11
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Kalyna M, Barta A. A plethora of plant serine/arginine-rich proteins: redundancy or evolution of novel gene functions? Biochem Soc Trans 2005; 32:561-4. [PMID: 15270675 PMCID: PMC5362061 DOI: 10.1042/bst0320561] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Precursor-mRNA (pre-mRNA) processing is an important step in gene expression and its regulation leads to the expansion of the gene product repertoire. SR (serine-arginine)-rich proteins are key players in intron recognition and spliceosome assembly and significantly contribute to the alternative splicing process. Due to several duplication events, at least 19 SR proteins are present in the Arabidopsis genome, which is almost twice as many as in humans. They fall into seven different subfamilies, three of them homologous with metazoan splicing factors, whereas the other four seem to be specific for plants. The current results show that most of the duplicated genes have different spatiotemporal expression patterns indicating functional diversification. Interestingly, most of the SR protein genes are alternatively spliced and in some cases this process was shown to be under developmental and/or environmental control. This might greatly influence gene expression of target genes as also exemplified by ectopic expression studies of particular SR proteins.
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Affiliation(s)
| | - Andrea Barta
- To whom correspondence should be addressed: Dr. Andrea Barta, Max F. Perutz Laboratories, University Departments at the Vienna Biocenter, Department of Biochemistry, Medical University of Vienna, Dr. Bohrgasse 9/3, A-1030 Vienna, Austria, Tel. +43-1-427761640, Fax. +43-1-42779616,
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12
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Gupta S, Wang BB, Stryker GA, Zanetti ME, Lal SK. Two novel arginine/serine (SR) proteins in maize are differentially spliced and utilize non-canonical splice sites. ACTA ACUST UNITED AC 2005; 1728:105-14. [PMID: 15780972 DOI: 10.1016/j.bbaexp.2005.01.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2004] [Revised: 12/28/2004] [Accepted: 01/04/2005] [Indexed: 11/20/2022]
Abstract
The serine-arginine (SR)-rich splicing proteins are highly conserved RNA binding nuclear phosphor-proteins that play important roles in both regular and alternative splicing. Here we describe two novel putative SR genes from maize, designated zmRSp31A and zmRSp31B. Both genes contain characteristic RNA binding motifs RNP-1 and RNP-2, a serine/arginine-rich (RS) domain and share significant sequence similarity to the Arabidopsis atRSp31 family of SR proteins. Both zmRSp31A and zmRSp31B produce multiple transcripts by alternative splicing, of which majority of the alternatively spliced transcripts utilize non-canonical splice sites. zmRSp31A and zmRSp31B produce at least six and four transcripts, respectively, of which only one corresponds to the wild type proteins for each gene. All the alternatively spliced transcripts of both the genes, with one exception, are predicted to encode small truncated proteins containing only the RNP-2 domain of their first RNA recognition motif and completely lack the carboxyl terminal RS domain. We provide evidence that some of the alternatively spliced transcripts of both genes are associated with polysomes and interact with the translational machinery.
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Affiliation(s)
- Smriti Gupta
- Department of Biological Sciences, Oakland University, Rochester, MI 48309-4401, USA
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13
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Tang M, Shen Y, Hu Y, Cao L, Ni T, Zhang H, Lin Z. Allergenicity assay of allergen fromDermatophagoides farinae in transgenic tobacco. CHINESE SCIENCE BULLETIN-CHINESE 2004. [DOI: 10.1007/bf02900963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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14
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Golovkin M, Reddy AS. An SC35-like protein and a novel serine/arginine-rich protein interact with Arabidopsis U1-70K protein. J Biol Chem 1999; 274:36428-38. [PMID: 10593939 DOI: 10.1074/jbc.274.51.36428] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The U1 small nuclear ribonucleoprotein 70-kDa protein, a U1 small nuclear ribonucleoprotein-specific protein, has been shown to have multiple roles in nuclear precursor mRNA processing in animals. By using the C-terminal arginine-rich region of Arabidopsis U1-70K protein in the yeast two-hybrid system, we have identified an SC35-like (SR33) and a novel plant serine/arginine-rich (SR) protein (SR45) that interact with the plant U1-70K. The SR33 and SR45 proteins share several features with SR proteins including modular domains typical of splicing factors in the SR family of proteins. However, both plant SR proteins are rich in proline, and SR45, unlike most animal SR proteins, has two distinct arginine/serine-rich domains separated by an RNA recognition motif. By using coprecipitation assays we confirmed the interaction of plant U1-70K with SR33 and SR45 proteins. Furthermore, in vivo and in vitro protein-protein interaction experiments have shown that SR33 protein interacts with itself and with SR45 protein but not with two other members (SRZ21 and SRZ22) of the SR family that are known to interact with the Arabidopsis full-length U-70K only. A Clk/Sty protein kinase (AFC-2) from Arabidopsis phosphorylated four SR proteins (SR33, SR45, SRZ21, and SRZ22). Coprecipitation studies have confirmed the interaction of SR proteins with AFC2 kinase, and the interaction between AFC2 and SR33 is modulated by the phosphorylation status of these proteins. These and our previous results suggest that the plant U1-70K interacts with at least four distinct members of the SR family including SR45 with its two arginine/serine-rich domains, and the interaction between the SR proteins and AFC2 is modulated by phosphorylation. The interaction of plant U1-70K with a novel set of proteins suggests the early stages of spliceosome assembly, and intron recognition in plants is likely to be different from animals.
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Affiliation(s)
- M Golovkin
- Department of Biology and Program in Cell and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523, USA
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15
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Lal S, Choi JH, Shaw JR, Hannah LC. A splice site mutant of maize activates cryptic splice sites, elicits intron inclusion and exon exclusion, and permits branch point elucidation. PLANT PHYSIOLOGY 1999; 121:411-8. [PMID: 10517832 PMCID: PMC59403 DOI: 10.1104/pp.121.2.411] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/1999] [Accepted: 06/25/1999] [Indexed: 05/17/2023]
Abstract
DNA sequence analysis of the bt2-7503 mutant allele of the maize brittle-2 gene revealed a point mutation in the 5' terminal sequence of intron 3 changing GT to AT. This lesion completely abolishes use of this splice site, activates two cryptic splice sites, and alters the splicing pattern from extant splice sites. One activated donor site, located nine nt 5' to the normal splice donor site, begins with the dinucleotide GC. While non-consensus, this sequence still permits both trans-esterification reactions of pre-mRNA splicing. A second cryptic site located 23 nt 5' to the normal splice site and beginning with GA, undergoes the first trans-esterification reaction leading to lariat formation, but lacks the ability to participate in the second reaction. Accumulation of this splicing intermediate and use of an innovative reverse transcriptase-polymerase chain reaction technique (J. Vogel, R.H. Wolfgang, T. Borner [1997] Nucleic Acids Res 25: 2030-2031) led to the identification of 3' intron sequences needed for lariat formation. In most splicing reactions, neither cryptic site is recognized. Most mature transcripts include intron 3, while the second most frequent class lacks exon 3. Traditionally, the former class of transcripts is taken as evidence for the intron definition of splicing, while the latter class has given credence to the exon definition of splicing.
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Affiliation(s)
- S Lal
- Program in Plant Molecular and Cellular Biology and Horticultural Sciences, 1143 Fifield Hall, P.O. Box 110690, University of Florida, Gainesville, Florida 32611-0690, USA
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16
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Lal S, Choi JH. The AG dinucleotide terminating introns is important but not always required for pre-mRNA splicing in the maize endosperm. PLANT PHYSIOLOGY 1999; 120:65-72. [PMID: 10318684 PMCID: PMC59270 DOI: 10.1104/pp.120.1.65] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/1998] [Accepted: 01/25/1999] [Indexed: 05/18/2023]
Abstract
Previous RNA analysis of lesions within the 15 intron-containing Sh2 (shrunken2) gene of maize (Zea mays) revealed that the majority of these mutants affect RNA splicing. Here we decipher further two of these mutants, sh2-i (shrunken2 intermediate phenotype) and sh2-7460. Each harbors a G-to-A transition in the terminal nucleotide of an intron, hence destroying the invariant AG found at the terminus of virtually all nuclear introns. Consequences of the mutations, however, differ dramatically. In sh2-i the mutant site is recognized as an authentic splice site in approximately 10% of the primary transcripts processed in the maize endosperm. The other transcripts exhibited exon skipping and lacked exon 3. A G-to-A transition in the terminus of an intron was also found in the mutant sh2-7460, in this case intron 12. The lesion activates a cryptic acceptor site downstream 22 bp within exon 13. In addition, approximately 50% of sh2-7460 transcripts contain intron 2 and 3 sequences.
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Affiliation(s)
- S Lal
- Program in Plant Molecular and Cellular Biology and Horticultural Sciences, 1143 Fifield Hall, P.O. Box 110690, University of Florida, Gainesville, Florida 32611-0690, USA
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17
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Lopato S, Kalyna M, Dorner S, Kobayashi R, Krainer AR, Barta A. atSRp30, one of two SF2/ASF-like proteins from Arabidopsis thaliana, regulates splicing of specific plant genes. Genes Dev 1999; 13:987-1001. [PMID: 10215626 PMCID: PMC316644 DOI: 10.1101/gad.13.8.987] [Citation(s) in RCA: 133] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/1998] [Accepted: 02/18/1999] [Indexed: 11/24/2022]
Abstract
SR proteins are nuclear phosphoproteins with a characteristic Ser/Arg-rich domain and one or two RNA recognition motifs. They are highly conserved in animals and plants and play important roles in spliceosome assembly and alternative splicing regulation. We have now isolated and partially sequenced a plant protein, which crossreacts with antibodies to human SR proteins. The sequence of the corresponding cDNA and genomic clones from Arabidopsis revealed a protein, atSRp30, with strong similarity to the human SR protein SF2/ASF and to atSRp34/SR1, a previously identified SR protein, indicating that plants possess two SF2/ASF-like proteins. atSRp30 expresses alternatively spliced mRNA isoforms that are expressed differentially in various organs and during development. Overexpression of atSRp30 via a strong constitutive promoter resulted in changes in alternative splicing of several endogenous plant genes, including atSRp30 itself. Interestingly, atSRp30 overexpression resulted in a pronounced down-regulation of endogenous mRNA encoding full-length atSRp34/SR1 protein. Transgenic plants overexpressing atSRp30 showed morphological and developmental changes affecting mostly developmental phase transitions. atSRp30- and atSRp34/SR1-promoter-GUS constructs exhibited complementary expression patterns during early seedling development and root formation, with overlapping expression in floral tissues. The results of the structural and expression analyses of both genes suggest that atSRp34/SR1 acts as a general splicing factor, whereas atSRp30 functions as a specific splicing modulator.
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Affiliation(s)
- S Lopato
- Institut für Biochemie, Universität Wien, Vienna Biocenter, A-1030 Vienna, Austria
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18
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Metzenberg S, Agabian N. Human and fungal 3' splice sites are used by Trypanosoma brucei for trans splicing. Mol Biochem Parasitol 1996; 83:11-23. [PMID: 9010838 DOI: 10.1016/s0166-6851(96)02742-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
In Trypanosoma brucei, pre-mRNAs are joined to a 5' 39 nt spliced leader sequence by trans splicing, a process that has not been well characterized. We have asked whether the 3' splice site regions of human and yeast introns are able to substitute in vivo for the 3' spliced leader acceptor regions of trypanosome pre-mRNA sequences. The ability of heterologous sequences to participate in trans splicing in trypanosomes was assayed by chloramphenicol acetyltransferase (CAT) enzyme activity and/or the detection of spliced CAT mRNA. Four out of the six heterologous 3' splice site regions (human beta-globin intervening sequence (IVS)2, human c-myc IVS2, human factor-VIII IVS1, and yeast actin IVS) functioned as 3' spliced leader acceptor regions in T. brucei, while two did not show significant or detectable levels of CAT activity (human beta-globin IVS1 and human c-myc IVS1). In the case of the human beta-globin IVS1 however, lengthening of the polypyrimidine tract as a result of single purine to pyrimidine transversions produced an active acceptor in which the spliced leader addition site coincides with the 3' splice site of the beta-globin exon 2. These studies indicate that some, but not all 3' acceptor regions in humans can function as spliced leader addition sites in trypansomes.
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Affiliation(s)
- S Metzenberg
- Intercampus Program in Molecular Parasitology, University of California-San Francisco 94143-1204, USA
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19
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Simpson GG, Filipowicz W. Splicing of precursors to mRNA in higher plants: mechanism, regulation and sub-nuclear organisation of the spliceosomal machinery. PLANT MOLECULAR BIOLOGY 1996; 32:1-41. [PMID: 8980472 DOI: 10.1007/bf00039375] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The removal of introns from pre-mRNA transcripts and the concomitant ligation of exons is known as pre-mRNA splicing. It is a fundamental aspect of constitutive eukaryotic gene expression and an important level at which gene expression is regulated. The process is governed by multiple cis-acting elements of limited sequence content and particular spatial constraints, and is executed by a dynamic ribonucleoprotein complex termed the spliceosome. The mechanism and regulation of pre-mRNA splicing, and the sub-nuclear organisation of the spliceosomal machinery in higher plants is reviewed here. Heterologous introns are often not processed in higher plants indicating that, although highly conserved, the process of pre-mRNA splicing in plants exhibits significant differences that distinguish it from splicing in yeast and mammals. A fundamental distinguishing feature is the presence of and requirement for AU or U-rich intron sequence in higher-plant pre-mRNA splicing. In this review we document the properties of higher-plant introns and trans-acting spliceosomal components and discuss the means by which these elements combine to determine the accuracy and efficiency of pre-mRNA processing. We also detail examples of how introns can effect regulated gene expression by affecting the nature and abundance of mRNA in plants and list the effects of environmental stresses on splicing. Spliceosomal components exhibit a distinct pattern of organisation in higher-plant nuclei. Effective probes that reveal this pattern have only recently become available, but the domains in which spliceosomal components concentrate were identified in plant nuclei as enigmatic structures some sixty years ago. The organisation of spliceosomal components in plant nuclei is reviewed and these recent observations are unified with previous cytochemical and ultrastructural studies of plant ribonuleoprotein domains.
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Affiliation(s)
- G G Simpson
- Friedrich Miescher-Institut, Basel, Switzerland
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20
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Lopato S, Mayeda A, Krainer AR, Barta A. Pre-mRNA splicing in plants: characterization of Ser/Arg splicing factors. Proc Natl Acad Sci U S A 1996; 93:3074-9. [PMID: 8610170 PMCID: PMC39763 DOI: 10.1073/pnas.93.7.3074] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The fact that animal introns are not spliced out in plants suggests that recognition of pre-mRNA splice sites differs between the two kingdoms. In plants, little is known about proteins required for splicing, as no plant in vitro splicing system is available. Several essential splicing factors from animals, such as SF2/ASF and SC-35, belong to a family of highly conserved proteins consisting of one or two RNA binding domain(s) (RRM) and a C-terminal Ser/Arg-rich (SR or RS) domain. These animal SR proteins are required for splice site recognition and spliceosome assembly. We have screened for similar proteins in plants by using monoclonal antibodies specific for a phosphoserine epitope of the SR proteins (mAb1O4) or for SF2/ASF. These experiments demonstrate that plants do possess SR proteins, including SF2/ASF-like proteins. Similar to the animal SR proteins, this group of proteins can be isolated by two salt precipitations. However, compared to the animal SR proteins, which are highly conserved in size and number, SR proteins from Arabidopsis, carrot, and tobacco exhibit a complex pattern of intra- and interspecific variants. These plant SR proteins are able to complement inactive HeLa cell cytoplasmic S1OO extracts that are deficient in SR proteins, yielding functional splicing extracts. In addition, plant SR proteins were active in a heterologous alternative splicing assay. Thus, these plant SR proteins are authentic plant splicing factors.
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Affiliation(s)
- S Lopato
- Institute of Biochemistry, Vienna Biocenter, Austria
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21
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Lazar G, Schaal T, Maniatis T, Goodman HM. Identification of a plant serine-arginine-rich protein similar to the mammalian splicing factor SF2/ASF. Proc Natl Acad Sci U S A 1995; 92:7672-6. [PMID: 7644475 PMCID: PMC41207 DOI: 10.1073/pnas.92.17.7672] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
We show that the higher plant Arabidopsis thaliana has a serine-arginine-rich (SR) protein family whose members contain a phosphoepitope shared by the animal SR family of splicing factors. In addition, we report the cloning and characterization of a cDNA encoding a higher-plant SR protein from Arabidopsis, SR1, which has striking sequence and structural homology to the human splicing factor SF2/ASF. Similar to SF2/ASF, the plant SR1 protein promotes splice site switching in mammalian nuclear extracts. A novel feature of the Arabidopsis SR protein is a C-terminal domain containing a high concentration of proline, serine, and lysine residues (PSK domain), a composition reminiscent of histones. This domain includes a putative phosphorylation site for the mitotic kinase cyclin/p34cdc2.
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Affiliation(s)
- G Lazar
- Department of Molecular Biology, Massachusetts General Hospital, Boston 02114, USA
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22
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Carle-Urioste JC, Ko CH, Benito MI, Walbot V. In vivo analysis of intron processing using splicing-dependent reporter gene assays. PLANT MOLECULAR BIOLOGY 1994; 26:1785-1795. [PMID: 7858217 DOI: 10.1007/bf00019492] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The mechanisms of intron recognition and processing have been well-studied in mammals and yeast, but in plants the biochemistry of splicing is not known and the rules for intron recognition are not clearly defined. To increase understanding of intron processing in plants, we have constructed new pairs of vectors, pSuccess and pFail, to assess the efficiency of splicing in maize cells. In the pFail series we use translation of pre-mRNA to monitor the amount of unspliced RNA. We inserted an ATG codon in the Bz2 (Bronze-2) intron in frame with luciferase: this construct will express luciferase activity only when splicing fails. In the pSuccess series the spliced message is monitored by inserting an ATG upstream of the Bz2 intron in frame with luciferase: this construct will express luciferase activity only when splicing succeeds. We show here, using both the wild-type Bz2 intron and the same intron with splice site mutations, that the efficiency of splicing can be estimated by the ratio between the luciferase activities of the vector pairs. We also show that mutations in the unique U-rich motif inside the intron can modulate splicing. In addition, a GC-rich insertion in the first exon increases the efficiency of splicing, suggesting that exons also play an important role in intron recognition and/or processing.
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Affiliation(s)
- J C Carle-Urioste
- Department of Biological Sciences, Stanford University, CA 94305-5020
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23
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Luehrsen KR, Walbot V. Addition of A- and U-rich sequence increases the splicing efficiency of a deleted form of a maize intron. PLANT MOLECULAR BIOLOGY 1994; 24:449-63. [PMID: 8123788 DOI: 10.1007/bf00024113] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Plant introns are generally short (< 200 nt) and AU-rich, and an elevated AU content is necessary for efficient splicing. Further, an intron in some plant genes enhances gene expression by a post-transcriptional mechanism that results in an increase of cytoplasmic mRNA. The specific intron features responsible for efficient splicing and enhancement are not well characterized in plants. Internal deletions of up to 80% of two maize introns, Adh1 intron 1 and maize actin 3, indicate that large segments of these introns are dispensable for normal function. However, extensive deletion (> 75%) of Adh1 intron 1 diminishes both intron enhancement and splicing efficiency. This finding suggests that there are internal sequence motifs required for intron function, and that these motifs are redundant. We attempted to repair a deletion-impaired Adh1 intron 1 variant by adding back either oligomers of defined sequence content or fragments of maize internal intron sequence. The addition of AU-rich oligomers improved splicing efficiency and in one example, a U-rich oligomer activated a cryptic 3' splice acceptor. We also found that replacing the region proximal to the Adh1 intron 1 3' acceptor with U-rich sequence improved splicing. We found that adding G- and C-rich oligomers did not improve intron function, but a C-rich oligomer activated a cryptic 3' acceptor. The addition of internal intron sequence to an impaired intron improved splicing, and in one case, resulted in the activation of a cryptic 3' acceptor. We present evidence that U-rich sequence immediately upstream of the 3' splice junction increases splicing efficiency and contributes to, but does not uniquely specify, 3' acceptor AG choice.
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Affiliation(s)
- K R Luehrsen
- Dept. of Biological Sciences, Stanford University, CA 94305-5020
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24
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Luehrsen KR, Taha S, Walbot V. Nuclear pre-mRNA processing in higher plants. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 1994; 47:149-93. [PMID: 8016320 DOI: 10.1016/s0079-6603(08)60252-4] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- K R Luehrsen
- Department of Biological Sciences, Stanford University, California 94305
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25
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Brown JW, Simpson CG, Simpson GG, Turnbull-Ross AD, Clark GP. Plant pre-mRNA splicing and splicing components. Philos Trans R Soc Lond B Biol Sci 1993; 342:217-24. [PMID: 8115450 DOI: 10.1098/rstb.1993.0150] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Pre-mRNA splicing or the removal of introns from precursor messenger RNAs depends on the accurate recognition of intron sequences by the plant splicing machinery. The major components of this machinery are small nuclear ribonucleoprotein protein particles (snRNPs) which consist of snRNAs and snRNP proteins. We have analysed various aspects of intron sequence and structure in relation to splice site selection and splicing efficiency and we have cloned snRNA genes and a gene encoding the snRNP protein, U2B". In the absence of an in vitro splicing system for plants, transient expression in protoplasts and stable plant transformations have been used to analyse splicing of intron constructs. We aim to address the function of the UsnRNP-specific protein, U2B", via the production of transgenic plants expressing antisense U2B" transcripts and epitope-tagged U2B" protein. In addition, we have cloned genes encoding other proteins which potentially interact with RNA, such as RNA helicases, and strategies involving transgenic plants are being developed to analyse their function.
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Affiliation(s)
- J W Brown
- Cell and Molecular Genetics Department, Scottish Crop Research Institute, Invergowrie, Dundee, U.K
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26
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Abstract
In contrast to mammalian and yeast systems, the mechanism for intron recognition and splice site selection in plant pre-mRNAs is poorly understood. Splice site sequences and putative branchpoint sequences are loosely conserved in plant introns compared with other eukaryotes. Perhaps to compensate for these variations, plant introns are significantly richer in adenosine and uridine residues than are their adjacent exons. To define elements critical for 3' splice site selection in dicotyledonous plant nuclei, pre-mRNA transcripts containing intron 3 of the maize Adh1 gene were expressed in Nicotiana benthamiana nuclei by using an autonomously replicating plant expression vector. Using a series of intron rearrangements which reposition the 3' intron-exon border, we demonstrate that the normal 3' splice site is defined in a position-dependent manner and that cryptic 3' splice sites within the intron are masked by the presence of a functional downstream 3' splice site. Disruption of the AU-rich elements upstream from the normal 3' splice site indicates that multiple AU elements between -66 and -6 cooperatively define the 3' boundary of the intron. These results are consistent with a model for plant intron recognition in which AU-rich elements spread throughout the length of the intron roughly define the intron boundaries by generating strong AU transition points. Functional 3' splice sites located downstream from these AU-rich sequences are preferentially selected over sites embedded within them.
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27
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Lou H, McCullough AJ, Schuler MA. 3' splice site selection in dicot plant nuclei is position dependent. Mol Cell Biol 1993; 13:4485-93. [PMID: 8336697 PMCID: PMC360058 DOI: 10.1128/mcb.13.8.4485-4493.1993] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
In contrast to mammalian and yeast systems, the mechanism for intron recognition and splice site selection in plant pre-mRNAs is poorly understood. Splice site sequences and putative branchpoint sequences are loosely conserved in plant introns compared with other eukaryotes. Perhaps to compensate for these variations, plant introns are significantly richer in adenosine and uridine residues than are their adjacent exons. To define elements critical for 3' splice site selection in dicotyledonous plant nuclei, pre-mRNA transcripts containing intron 3 of the maize Adh1 gene were expressed in Nicotiana benthamiana nuclei by using an autonomously replicating plant expression vector. Using a series of intron rearrangements which reposition the 3' intron-exon border, we demonstrate that the normal 3' splice site is defined in a position-dependent manner and that cryptic 3' splice sites within the intron are masked by the presence of a functional downstream 3' splice site. Disruption of the AU-rich elements upstream from the normal 3' splice site indicates that multiple AU elements between -66 and -6 cooperatively define the 3' boundary of the intron. These results are consistent with a model for plant intron recognition in which AU-rich elements spread throughout the length of the intron roughly define the intron boundaries by generating strong AU transition points. Functional 3' splice sites located downstream from these AU-rich sequences are preferentially selected over sites embedded within them.
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Affiliation(s)
- H Lou
- Department of Plant Biology, University of Illinois, Urbana 61801
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28
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Lou H, McCullough AJ, Schuler MA. Expression of maize Adh1 intron mutants in tobacco nuclei. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 1993; 3:393-403. [PMID: 8220449 DOI: 10.1046/j.1365-313x.1993.t01-22-00999.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
In vivo and in vitro gene transfer experiments have suggested that the elements mediating intron recognition differ in mammalian, yeast and plant nuclei. Differences in the sequence dependencies, which also exist between dicotyledonous and monocotyledonous nuclei, have prevented some monocot introns from being spliced in dicot nuclei. To locate elements which modulate efficient recognition of introns in dicot nuclei, the maize Adh1 gene has been expressed in full-length and single intron constructs in Nicotiana benthamiana nuclei using an autonomously replicating plant expression vector. Quantitative PCR-Southern analyses indicate that the inefficient splicing of the maize Adh1 intron 1 (57% AU) in these dicot nuclei can be dramatically enhanced by increasing the degree of U1 snRNA complementarity at the 5' splice site. This indicates that the 5' splice site plays a significant role in defining the splicing efficiency of an intron in dicot nuclei and that, most importantly, the remainder of this monocot intron contains no elements which inhibit its accurate recognition in dicot nuclei. Deletions in intron 3 (66% AU) which effectively move the 3' boundary between AU-rich intron and GC-rich exon sequences strongly activate a cryptic upstream splice site; those which do not reposition this boundary activate a downstream cryptic splice site. This suggests that 3' splice site selection in dicot nuclei is extremely flexible and not dependent on strict sequence requirements but rather on the transition points between introns and exons. Our results are consistent with a model in which potential splice sites are selected if they are located upstream (5' splice site) or downstream (3' splice site) of AU transition points and not if they are embedded within AU-rich sequences.
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Affiliation(s)
- H Lou
- Department of Plant Biology, University of Illinois, Urbana 61801
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29
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Abstract
Amplification and sequencing of part of the coding regions of the catalytic V-type ATPase subunit shows the presence of (at least) two genes in all land plants as well as the conservative insertion of a noncoding sequence. The two genes exhibit a coding region of the same length but differ in the number of nucleotides present in the intron. The latter is surprisingly conserved suggesting the presence of functional constraints on the intron sequences. The findings presented in this report indicate that introns from plants and animals are characterized by different internal structural elements.
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Affiliation(s)
- T Starke
- University of Connecticut, Department of Molecular and Cell Biology, Storrs 06269-3044
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30
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Simpson CG, Brown JW. Efficient splicing of an AU-rich antisense intron sequence. PLANT MOLECULAR BIOLOGY 1993; 21:205-11. [PMID: 7678764 DOI: 10.1007/bf00019937] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
For successful splicing in dicot plants the only recognised intron requirements are 5' and 3' splice sites and AU-rich sequences. We have investigated further the importance of AU-rich elements by analyzing the splicing of an AU-rich antisense intron sequence. Activation of cryptic splice sites on either side of the AU-rich sequence permitted the efficient removal of this essentially non-intron sequence by splicing. This splicing event not only confirms the importance of AU-rich sequences but also has implications for the evolution of interrupted genes and the expression of heterologous genes in transgenic plants.
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Affiliation(s)
- C G Simpson
- Cell and Molecular Genetics Department, Scottish Crop Research Institute, Dundee, UK
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31
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Reddy AS, Czernik AJ, An G, Poovaiah BW. Cloning of the cDNA for U1 small nuclear ribonucleoprotein particle 70K protein from Arabidopsis thaliana. BIOCHIMICA ET BIOPHYSICA ACTA 1992; 1171:88-92. [PMID: 1420366 DOI: 10.1016/0167-4781(92)90143-n] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
We cloned and sequenced a plant cDNA that encodes U1 small nuclear ribonucleoprotein (snRNP) 70K protein. The plant U1 snRNP 70K protein cDNA is not full length and lacks the coding region for 68 amino acids in the amino-terminal region as compared to human U1 snRNP 70K protein. Comparison of the deduced amino acid sequence of the plant U1 snRNP 70K protein with the amino acid sequence of animal and yeast U1 snRNP 70K protein showed a high degree of homology. The plant U1 snRNP 70K protein is more closely related to the human counter part than to the yeast 70K protein. The carboxy-terminal half is less well conserved but, like the vertebrate 70K proteins, is rich in charged amino acids. Northern analysis with the RNA isolated from different parts of the plant indicates that the snRNP 70K gene is expressed in all of the parts tested. Southern blotting of genomic DNA using the cDNA indicates that the U1 snRNP 70K protein is coded by a single gene.
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Affiliation(s)
- A S Reddy
- Department of Horticulture and Landscape Architecture, Washington State University, Pullman
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32
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Luehrsen KR, Walbot V. Insertion of non-intron sequence into maize introns interferes with splicing. Nucleic Acids Res 1992; 20:5181-7. [PMID: 1383942 PMCID: PMC334303 DOI: 10.1093/nar/20.19.5181] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Transposable element (TE) insertion into or near plant introns can cause intron skipping and alternative splicing events, resulting in reduced expression. To explore the impact of inserted sequences on splicing, we added non-intron sequence to two maize introns and tested these chimeric introns in a maize transient expression assay. Non-intron sequence inserted into Adh1-S intron 1 and actin intron 3 decreased expression from the luciferase reporter gene; the insertion sites tested were not in intron regions thought to be essential for splicing. Alternatively spliced mRNAs were not observed in transcripts derived from the insertion variants. In contrast, addition of an internal segment of an intron to Adh1-S intron 1 resulted in normal splice site selection and efficient processing. Because the normal intron sequence (including the conserved splice junctions) was retained in all constructs, we hypothesize that added non-intron sequence can interfere with intron recognition and/or splicing.
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Affiliation(s)
- K R Luehrsen
- Department of Biological Sciences, Stanford University, CA 94305
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33
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Paszkowski J, Peterhans A, Bilang R, Filipowicz W. Expression in transgenic tobacco of the bacterial neomycin phosphotransferase gene modified by intron insertions of various sizes. PLANT MOLECULAR BIOLOGY 1992; 19:825-36. [PMID: 1322741 DOI: 10.1007/bf00027078] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2023]
Abstract
A plant selectable marker gene consisting of cauliflower mosaic virus expression signals and the protein-coding sequence of bacterial neomycin phosphotransferase was modified by insertion of an intron sequence from a storage protein gene, phaseolin. Correct and efficient splicing of the resulting mosaic RNA was observed in transgenic tobacco plants. The insertion of various linkers or gradual increase of intron size by addition in both orientations of internal intron sequences from another plant gene (parsley, 4-coumarate ligase) had little or no effect on the precision of slicing. The gene activity measured by selectability assay in the protoplast transformation showed that only introns enlarged to 1161 bases and longer caused decreased selectability. The suitability of such mosaic marker genes for studies of RNA splicing, DNA recombination and early events after infection of plants with Agrobacterium is discussed.
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Affiliation(s)
- J Paszkowski
- Swiss Federal Institute of Technology, Institute of Plant Sciences, ETH-Zentrum, Zürich
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34
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Laliberté JF, Nicolas O, Durand S, Morosoli R. The xylanase introns from Cryptococcus albidus are accurately spliced in transgenic tobacco plants. PLANT MOLECULAR BIOLOGY 1992; 18:447-51. [PMID: 1536922 DOI: 10.1007/bf00040660] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The xylanase gene from Cryptococcus albidus contains seven introns. Genomic and cDNA clones under the control of the CaMV 35S promoter were transferred into tobacco plants using Agrobacterium-mediated cell transformation. The genes were transcribed and the mRNAs were amplified by the polymerase chain reaction using primers on each side of the intron region. About 90% of the amplification products from plants transformed with the genomic clone corresponded to the size of the pre-mRNA (1.2 kb) and 10% represented the spliced product (0.85 kb). The 0.85 kb fragment was cloned and sequenced and the result indicated that the introns from the xylanase gene were accurately spliced by the plant cells.
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Affiliation(s)
- J F Laliberté
- Institut Armand-Frappier, Ville de Laval, Québec, Canada
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35
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Waigmann E, Barta A. Processing of chimeric introns in dicot plants: evidence for a close cooperation between 5' and 3' splice sites. Nucleic Acids Res 1992; 20:75-81. [PMID: 1738607 PMCID: PMC310328 DOI: 10.1093/nar/20.1.75] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Splice sites of vertebrate introns are generally not recognized in plant cells. Several lines of evidences have led to the proposal that the mechanism of 3' splice site selection differs in plants and animals (K. Wiebauer, J.J. Herrero, and W. Filipowicz, Mol. Cell. Biol. 8:2042-2051, 1988). To gain a better insight into the mechanistic differences between plant and animal splicing, we constructed chimeric introns consisting partly of dicotyledonous plant and partly of animal intron sequences. Splicing of these chimeric introns was analyzed in transiently transfected tobacco protoplasts. The results show that there are no principal sequence or structural differences between the 3' splice regions of plants and animals. Furthermore, evidence is provided that cooperation between 5' and 3' splice sites takes place and influences their mutual selection.
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Affiliation(s)
- E Waigmann
- Institut für Biochemie, Universität Wien, Vienna, Austria
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36
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Sinibaldi RM, Mettler IJ. Intron splicing and intron-mediated enhanced expression in monocots. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 1992; 42:229-57. [PMID: 1574588 DOI: 10.1016/s0079-6603(08)60577-2] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- R M Sinibaldi
- Sandoz Agro, Inc., Plant Biotechnology Department, Palo Alto, California 94304
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37
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McCullough AJ, Lou H, Schuler MA. In vivo analysis of plant pre-mRNA splicing using an autonomously replicating vector. Nucleic Acids Res 1991; 19:3001-9. [PMID: 2057358 PMCID: PMC328263 DOI: 10.1093/nar/19.11.3001] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
In this paper, we demonstrate that an autonomously replicating plant expression vector can be used for analysis of pre-mRNA splicing determinants in intact dicot cells. This vector system relies on the Agrobacterium-mediated transfection of leaf discs with the A component of the geminivirus tomato golden mosaic virus (TGMV). Insertion of intron sequences between viral promoter and terminator sequences results in the production of high levels of pre-mRNA transcripts that are effectively and accurately spliced in vivo. Introns from the soybean B-conglycinin gene are spliced at greater than 95% efficiency indicating that the high expression levels of precursor RNA do not exceed the intron splicing capacity of these cells. Introns from the pea and wheat rbcS genes are spliced at 85% and 73% efficiency, respectively, indicating that tobacco leaf disc nuclei are capable of effectively and accurately processing particular dicot and monocot introns. Inclusion of a dicot intron in an engineered construct results in a five-fold enhancement of the level of mRNA stably expressed in dicot nuclei.
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Affiliation(s)
- A J McCullough
- Department of Plant Biology, University of Illinois, Urbana 61801
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38
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Hanley BA, Schuler MA. cDNA cloning of U1, U2, U4 and U5 snRNA families expressed in pea nuclei. Nucleic Acids Res 1991; 19:1861-9. [PMID: 2030967 PMCID: PMC328116 DOI: 10.1093/nar/19.8.1861] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Differences observed between plant and animal pre-mRNA splicing may be the result of primary or secondary structure differences in small nuclear RNAs (snRNAs). A cDNA library of pea snRNAs was constructed from anti-trimethylguanosine (m3(2,2,7)G immunoprecipitated pea nuclear RNA. The cDNA library was screened using oligo-deoxyribonucleotide probes specific for the U1, U2, U4 and U5 snRNAs. cDNA clones representing U1, U2, U4 and U5 snRNAs expressed in seedling tissue have been isolated and sequenced. Comparison of the pea snRNA variants with other organisms suggest that functionally important primary sequences are conserved phylogenetically even though the overall sequences have diverged substantially. Structural variations in U1 snRNA occur in regions required for U1-specific protein binding. In light of this sequence analysis, it is clear that the dicot snRNA variants do not differ in sequences implicated in RNA:RNA interactions with pre-mRNA. Instead, sequence differences occur in regions implicated in the binding of small ribonucleoproteins (snRNPs) to snRNAs and may result in the formation of unique snRNP particles.
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Affiliation(s)
- B A Hanley
- Department of Biochemistry, University of Illinois, Urbana 61801
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39
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Hunt AG, Mogen BD, Chu NM, Chua NH. The SV40 small t intron is accurately and efficiently spliced in tobacco cells. PLANT MOLECULAR BIOLOGY 1991; 16:375-9. [PMID: 1654158 DOI: 10.1007/bf00023989] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2023]
Abstract
We have introduced the SV40 small t intron into tobacco cells as part of a cauliflower mosaic virus 35S promoter-chloramphenicol acetyltransferase-SV40 transcription unit. We find that the small t intron is efficiently and accurately spliced in transgenic tobacco cells that carry this transcription unit. Our results indicate that there is substantial conservation of RNA processing signals between plants and animals, more than has been previously assumed. They also suggest that pre-mRNA processing in plants requires multiple branch sites for efficient processing.
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Affiliation(s)
- A G Hunt
- Department of Agronomy, University of Kentucky, Lexington 40546
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40
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Waugh R, Clark G, Vaux P, Brown JW. Sequence and expression of potato U2 snRNA genes. Nucleic Acids Res 1991; 19:249-56. [PMID: 2014165 PMCID: PMC333587 DOI: 10.1093/nar/19.2.249] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Plant UsnRNA multigene families show a high degree of sequence variation among individual gene members. The potato U2snRNA gene family consists of between twenty-five and forty genes. Four potato U2snRNA gene variants have been isolated. Despite the sequence variation in coding and flanking regions, all maintain the conserved U2snRNA secondary structure and all contain the plant UsnRNA promoter elements: the upstream sequence element (USE) and TATA-like box in the -70 and -30 regions respectively. In RNase A/T1 protection analyses, one of the genes, PotU2-22, protected high levels of full length U2snRNA transcripts in potato leaf, stem, root and tuber RNA. Thus, PotU2-22 or genes with identical coding regions, are highly expressed in these potato organs and therefore represent a major subset of functional U2snRNA genes. Similar expression levels of the PotU2-22 sequence variant were also found in four genetically different potato cultivars and also in tobacco, a species closely related to potato, suggesting conservation of the coding regions of expressed U2snRNA genes. A second gene, PotU2-4, protected very low levels of full length transcripts while a third gene, PotU2-11, was not expressed in the potato organs analysed. The relative expression levels of the gene variants may reflect individual gene differences in, for example, the USE and TATA regulatory elements, or variations in gene copy number.
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Affiliation(s)
- R Waugh
- Department of Cellular and Molecular Genetics, Scottish Crop Research Institute, Invergowrie, Dundee, UK
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41
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Grant CE, Bain G, Tsang A. The molecular basis for alternative splicing of the CABP1 transcripts in Dictyostelium discoideum. Nucleic Acids Res 1990; 18:5457-63. [PMID: 2216719 PMCID: PMC332224 DOI: 10.1093/nar/18.18.5457] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
We have determined the nucleotide sequence of the CABP1 gene from Dictyostelium discoideum. Together with previous data on cDNA sequences, we establish that alternative splicing of transcripts derived from this gene is responsible for the production of the two CABP1 subunits. RNA blot analysis suggested that alternative splicing of the CABP1 transcripts occurs during growth and throughout development. In addition, we have compiled the intron sequences of Dictyostelium pre-mRNAs and observed that the GUAAGU hexanucleotide at the 5' splice site is highly conserved. The 5' splice site of CABP1 deviates from the consensus hexanucleotide in having a sequence of GUAAUA. To assess the role of the modified 5' splice on differential splicing, we have constructed an actin-CABP1 fusion gene and transformed it into Dictyostelium cells. Analysis by immunoprecipitation, with anti-CABP1 antibody and amplification of specific cDNAs by polymerase chain reaction show that the transcripts generated by the fusion gene are alternatively spliced. When the 5' splice site of the fusion gene is mutated to conform to the consensus sequence, the resulting transcripts are constitutively spliced. These observations suggest that changes in positions 5 and 6 of the donor splice site are involved in the alternative splicing of the CABP1 transcripts.
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Affiliation(s)
- C E Grant
- Department of Biology, McGill University, Montreal, Quebec, Canada
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42
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Csank C, Taylor FM, Martindale DW. Nuclear pre-mRNA introns: analysis and comparison of intron sequences from Tetrahymena thermophila and other eukaryotes. Nucleic Acids Res 1990; 18:5133-41. [PMID: 2402440 PMCID: PMC332134 DOI: 10.1093/nar/18.17.5133] [Citation(s) in RCA: 138] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
We have sequenced 14 introns from the ciliate Tetrahymena thermophila and include these in an analysis of the 27 intron sequences available from seven T. thermophila protein-encoding genes. Consensus 5' and 3' splice junctions were determined and found to resemble the junctions of other nuclear pre-mRNA introns. Unique features are noted and discussed. Overall the introns have a mean A + T content of 85% (21% higher than neighbouring exons) with smaller introns tending towards a higher A + T content. Approximately half of the introns are less than 100 bp. Introns from other organisms (approximately 30 of each) were also examined. The introns of Dictyostelium discoideum, Caenorhabditis elegans and Drosophila melanogaster, like those of T. thermophila, have a much higher mean A + T content than their neighbouring exons (greater than 20%). Introns from plants, Neurospora crassa and Schizosaccharomyces pombe also have a significantly higher A + T content (10%-20%). Since a high A + T content is required for intron splicing in plants (58), the elevated A + T content in the introns of these other organisms may also be functionally significant. The introns of yeast (Saccharomyces cerevisiae) and mammals (humans) appear to lack this trait and thus in some aspects may be atypical. The polypyrimidine tract, so distinctive of vertebrate introns, is not a trait of the introns in the non-vertebrate organisms examined in this study.
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Affiliation(s)
- C Csank
- Department of Microbiology, Macdonald College, McGill University, Ste Anne de Bellevue, Canada
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43
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Brown JW, Feix G. A functional splice site in the 5' untranslated region of a zein gene. Nucleic Acids Res 1990; 18:111-7. [PMID: 2308817 PMCID: PMC330210 DOI: 10.1093/nar/18.1.111] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Zein genes, the genes coding for the zein storage proteins of maize, have a unique gene structure where at least two promoters lie upstream of the coding region. Between the P1 promoter (900 base pairs upstream of the coding region) and the translation initiation AUG codon are 18 short reading frames. A discrepancy between the signals obtained by S1-mapping and primer extension and the DNA sequence in the region of one of these signals suggests the presence of a 3' splice site lying 40 nucleotides upstream of the coding region. A splicing event removing all of the short reading frames from the mRNA transcribed from the P1 promoter would bring this mRNA into a translatable form. Further evidence for a functional 3' splice site has been obtained from sequencing of primer extension products and in vitro splicing of a hybrid intron in the HeLa cell in vitro splicing system.
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Affiliation(s)
- J W Brown
- Institut für Biologie III, Albert Ludwigs Universität, Freiburg, FRG
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44
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Goodall GJ, Wiebauer K, Filipowicz W. Analysis of pre-mRNA processing in transfected plant protoplasts. Methods Enzymol 1990; 181:148-61. [PMID: 1696344 DOI: 10.1016/0076-6879(90)81117-d] [Citation(s) in RCA: 112] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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45
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Abstract
The complexity of plant U-type small nuclear ribonucleoprotein particles (UsnRNPs) may represent one level at which differences in splicing between animals and plants and between monocotyledonous and dicotyledonous plants could be effected. The maize (monocot.) U2snRNA multigene family consists of some 25 to 40 genes which from RNA blot and RNase protection analyses produce U2snRNAs varying in both size and sequence. The first 77 nucleotides of the maize U2-27 snRNA gene are identical to U2snRNA genes of Arabidopsis (dicot). Despite much lower sequence homology in the remaining 120 nucleotides the secondary structure of the RNA is conserved. The difference in splicing between monocot. and dicot. plants cannot be explained on the basis of sequence differences between monocot, and dicot. U2snRNAs in the region which may interact with intron branch point sequences.
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Affiliation(s)
- J W Brown
- Department of Biological Sciences, University of Dundee, UK
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46
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Goodall GJ, Filipowicz W. The AU-rich sequences present in the introns of plant nuclear pre-mRNAs are required for splicing. Cell 1989; 58:473-83. [PMID: 2758463 DOI: 10.1016/0092-8674(89)90428-5] [Citation(s) in RCA: 250] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Plant cells do not in general process the introns of transcripts expressed from introduced vertebrate genes. By studying the processing of model introns in transfected plant protoplasts, we have investigated the special requirements for intron recognition by plant cells. Our results indicate that the requirements for intron recognition in plants are different from those of both metazoa and yeast. A synthetic intron of arbitrary sequence but incorporating splice site consensus sequences and a high proportion of U and A nucleotides, a characteristic feature of plant introns, was efficiently spliced in protoplasts. We have studied the effects of various sequence alterations and conclude that AU-rich sequences are necessary for intron recognition. In addition, we find that the criteria for branch site selection are relaxed, as they are in vertebrates, but a polypyrimidine tract is not necessary.
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Affiliation(s)
- G J Goodall
- Friedrich Miescher-Institut, Basel, Switzerland
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47
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Abstract
Three gene constructions based on a mouse metallothionein I gene (mMT-I) were introduced into tobacco using a Ri plasmid vector system to test the effectiveness of animal gene regulatory signals in plant cells. No transcription from the native mouse gene was observed. In plant cells bearing chimeric mMT-I genes in which transcription was driven by the nopaline synthase promoter, neither polyadenylation nor splicing of mMT-I pre-mRNA was observed. Detailed comparisons of mMT-I sequences with those of known plant genes were carried out; slight differences in regions of known consensus sequences may be at least partly responsible for the non-recognition of mMT-I gene regulatory signals in plant cells, though other as yet unidentified, potentially necessary sequences may also be involved.
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Affiliation(s)
- V Pautot
- Laboratoire de Biologie Cellulaire, INRA-Centre de Versailles, France
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48
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Martinez-Zapater JM, Finkelstein R, Somerville CR. Drosophila P-element transcripts are incorrectly processed in tobacco. PLANT MOLECULAR BIOLOGY 1988; 11:601-607. [PMID: 24272494 DOI: 10.1007/bf00017460] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/1988] [Accepted: 08/15/1988] [Indexed: 06/02/2023]
Abstract
A gene encoding the Drosophila P-element transposase was expressed in transgenic tobacco plants under transcriptional control of the Drosophila HSP70 promoter. Polyadenylated transcripts were produced, but the major transcript was about 1 kb shorter than expected and the two introns were not removed. The 3' end of the most abundant transcript occurred within the transposase coding sequence downstream of the acceptor site of the second intron within a region of high A+T content. These results provide an additional example in which RNA processing enzymes of plants utilize different mRNA processing signals than animals.
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Affiliation(s)
- J M Martinez-Zapater
- MSU-DOE Plant Research Laboratory, Michigan State University, 48824, East Lansing, MI, USA
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49
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Nuclear pre-mRNA processing in plants: distinct modes of 3'-splice-site selection in plants and animals. Mol Cell Biol 1988. [PMID: 3386632 DOI: 10.1128/mcb.8.5.2042] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The report that human growth hormone pre-mRNA is not processed in transgenic plant tissues (A. Barta, K. Sommergruber, D. Thompson, K. Hartmuth, M.A. Matzke, and A.J.M. Matzke, Plant Mol. Biol. 6:347-357, 1986) has suggested that differences in mRNA splicing processes exist between plants and animals. To gain more information about the specificity of plant pre-mRNA processing, we have compared the splicing of the soybean leghemoglobin pre-mRNA with that of the human beta-globin pre-mRNA in transfected plant (Orychophragmus violaceus and Nicotiana tabacum) protoplasts and mammalian (HeLa) cells. Of the three introns of leghemoglobin pre-mRNA, only intron 2 was correctly and efficiently processed in HeLa cells. The 5' splice sites of the remaining two introns were faithfully recognized, but correct processing of the 3' sites took place only rarely (intron 1) or not at all (intron 3); cryptic 3' splice sites were used instead. While the first intron in human beta-globin pre-mRNA was not spliced in transfected plant protoplasts, intron 2 processing occurred at a low level, indicating that some mammalian introns can be recognized by the plant intron-splicing machinery. However, excision of intron 2 proved to be incorrect, involving the authentic 5' splice site and a cryptic 3' splice site. Our results indicate that the mechanism of 3'-splice-site selection during intron excision differs between plants and animals. This conclusion is supported by analysis of the 3'-splice-site consensus sequences in animal and plant introns which revealed that polypyrimidine tracts, characteristic of animal introns, are not present in plant pre-mRNAs. It is proposed that an elevated AU content of plant introns is important for their processing.
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50
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Hanley BA, Schuler MA. Plant intron sequences: evidence for distinct groups of introns. Nucleic Acids Res 1988; 16:7159-76. [PMID: 3405760 PMCID: PMC338358 DOI: 10.1093/nar/16.14.7159] [Citation(s) in RCA: 129] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
In vivo and in vitro RNA splicing experiments have demonstrated that the intron splicing machineries are not interchangeable in all organisms. These differences have prevented the efficient in vivo expression of monocot genes containing introns in dicot plants and the in vitro excision of some plant introns in HeLa cell in vitro splicing extracts. We have analyzed plant introns for sequence differences which potentially account for the functional splicing differences. Three classes of plant introns can be differentiated by the purine or pyrimidine-richness of sequences upstream from the 3' splice site. The frequency of these three types of introns in monocots and dicots varies significantly. The degree of variability in the 5' and 3' intron boundaries is evaluated for each of these classes in monocots and dicots. The 5' splice site consensus sequences developed for the monocot and dicot introns differ in their ability to base pair with conserved nucleotides present at the 5' end of many U1 snRNAs.
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Affiliation(s)
- B A Hanley
- Department of Plant Biology, University of Illinois, Urbana 61801
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