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Abdel-Fattah WR, Carlsson M, Hu GZ, Singh A, Vergara A, Aslam R, Ronne H, Björklund S. Growth-regulated co-occupancy of Mediator and Lsm3 at intronic ribosomal protein genes. Nucleic Acids Res 2024; 52:6220-6233. [PMID: 38613396 PMCID: PMC11194063 DOI: 10.1093/nar/gkae266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Revised: 03/22/2024] [Accepted: 04/01/2024] [Indexed: 04/14/2024] Open
Abstract
Mediator is a well-known transcriptional co-regulator and serves as an adaptor between gene-specific regulatory proteins and RNA polymerase II. Studies on the chromatin-bound form of Mediator revealed interactions with additional protein complexes involved in various transcription-related processes, such as the Lsm2-8 complex that is part of the spliceosomal U6 small nuclear ribonucleoprotein complex. Here, we employ Chromatin Immunoprecipitation sequencing (ChIP-seq) of chromatin associated with the Lsm3 protein and the Med1 or Med15 Mediator subunits. We identify 86 genes co-occupied by both Lsm3 and Mediator, of which 73 were intron-containing ribosomal protein genes. In logarithmically growing cells, Mediator primarily binds to their promoter regions but also shows a second, less pronounced occupancy at their 3'-exons. During the late exponential phase, we observe a near-complete transition of Mediator from these promoters to a position in their 3'-ends, overlapping the Lsm3 binding sites ∼250 bp downstream of their last intron-exon boundaries. Using an unbiased RNA sequencing approach, we show that transition of Mediator from promoters to the last exon of these genes correlates to reduction of both their messenger RNA levels and splicing ratios, indicating that the Mediator and Lsm complexes cooperate to control growth-regulated expression of intron-containing ribosomal protein genes at the levels of transcription and splicing.
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Affiliation(s)
- Wael R Abdel-Fattah
- Department of Medical Biochemistry and Biophysics, Umeå University, SE-901 87 Umeå, Sweden
| | - Mattias Carlsson
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Box 7026, SE-750 07 Uppsala, Sweden
| | - Guo-Zhen Hu
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Box 7026, SE-750 07 Uppsala, Sweden
| | - Ajeet Singh
- Department of Medical Biochemistry and Biophysics, Umeå University, SE-901 87 Umeå, Sweden
| | - Alexander Vergara
- Department of Plant Physiology, Umeå University, SE-901 87 Umeå, Sweden
| | - Rameen Aslam
- Department of Medical Biochemistry and Biophysics, Umeå University, SE-901 87 Umeå, Sweden
| | - Hans Ronne
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Box 7026, SE-750 07 Uppsala, Sweden
| | - Stefan Björklund
- Department of Medical Biochemistry and Biophysics, Umeå University, SE-901 87 Umeå, Sweden
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2
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Gupta SS, Mishra V, Mukherjee MD, Saini P, Ranjan KR. Amino acid derived biopolymers: Recent advances and biomedical applications. Int J Biol Macromol 2021; 188:542-567. [PMID: 34384802 DOI: 10.1016/j.ijbiomac.2021.08.036] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 08/04/2021] [Accepted: 08/04/2021] [Indexed: 01/19/2023]
Abstract
Over the past few years, amino acids (AA) have emerged as promising biomaterials for the synthesis of functional polymers. Owing to the diversity of functional groups in amino acids, various polymerization methods may be used to make a wide range of well-defined functional amino-acid/peptide-based optically active polymers with varying polymer lengths, compositions, and designs. When incorporated with chirality and self-assembly, they offer a wide range of applications and are particularly appealing in the field of drug delivery, tissue engineering, and biosensing. There are several classes of these polymers that include polyamides (PA), polyesters (PE), poly(ester-amide)s (PEA)s, polyurethanes (PU)s, poly(depsipeptide)s (PDP)s, etc. They offer the ability to control functionality, conjugation, crosslinking, stimuli responsiveness, and tuneable mechanical/thermal properties. In this review, we present the recent advancements in the synthesis strategies for obtaining these amino acid-derived bio-macromolecules, their self-assembly properties, and the wealth of prevalent applications.
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Affiliation(s)
| | - Vivek Mishra
- Amity Institute of Click Chemistry Research and Studies, Amity University Uttar Pradesh, NOIDA, India.
| | | | | | - Kumar Rakesh Ranjan
- Amity Institute of Applied Sciences, Amity University Uttar Pradesh, NOIDA, India.
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3
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Vindry C, Weil D, Standart N. Pat1 RNA-binding proteins: Multitasking shuttling proteins. WILEY INTERDISCIPLINARY REVIEWS-RNA 2019; 10:e1557. [PMID: 31231973 DOI: 10.1002/wrna.1557] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Revised: 05/02/2019] [Accepted: 05/07/2019] [Indexed: 12/11/2022]
Abstract
Post-transcriptional regulation of gene expression is largely achieved at the level of splicing in the nucleus, and translation and mRNA decay in the cytosol. While the regulation may be global, through the direct inhibition of central factors, such as the spliceosome, translation initiation factors and mRNA decay enzymes, in many instances transcripts bearing specific sequences or particular features are regulated by RNA-binding factors which mobilize or impede recruitment of these machineries. This review focuses on the Pat1 family of RNA-binding proteins, conserved from yeast to man, that enhance the removal of the 5' cap by the decapping enzyme Dcp1/2, leading to mRNA decay and also have roles in translational repression. Like Dcp1/2, other decapping coactivators, including DDX6 and Edc3, and translational repressor proteins, Pat1 proteins are enriched in cytoplasmic P-bodies, which have a principal role in mRNA storage. They also concentrate in nuclear Cajal-bodies and splicing speckles and in man, impact splice site choice in some pre-mRNAs. Pivotal to these functions is the association of Pat1 proteins with distinct heptameric Lsm complexes: the cytosolic Pat1/Lsm1-7 complex mediates mRNA decay and the nuclear Pat1/Lsm2-8 complex alternative splicing. This dual role of human Pat1b illustrates the power of paralogous complexes to impact distinct processes in separate compartments. The review highlights our recent findings that Pat1b mediates the decay of AU-rich mRNAs, which are particularly enriched in P-bodies, unlike the decapping activator DDX6, which acts on GC-rich mRNAs, that tend to be excluded from P-bodies, and discuss the implications for mRNA decay pathways. This article is categorized under: RNA Turnover and Surveillance > Regulation of RNA Stability RNRNA Processing > Splicing Regulation/Alternative Splicing Translation > Translation Regulation.
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Affiliation(s)
- Caroline Vindry
- Centre International de Recherche en Infectiologie, CIRI, Lyon, France
| | - Dominique Weil
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine, Laboratoire de Biologie du Développement, Paris, France
| | - Nancy Standart
- Department of Biochemistry, University of Cambridge, Cambridge, UK
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4
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An Allosteric Network for Spliceosome Activation Revealed by High-Throughput Suppressor Analysis in Saccharomyces cerevisiae. Genetics 2019; 212:111-124. [PMID: 30898770 DOI: 10.1534/genetics.119.301922] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 03/15/2019] [Indexed: 12/30/2022] Open
Abstract
Selection of suppressor mutations that correct growth defects caused by substitutions in an RNA or protein can reveal functionally important molecular structures and interactions in living cells. This approach is particularly useful for the study of complex biological pathways involving many macromolecules, such as premessenger RNA (pre-mRNA) splicing. When a sufficiently large number of suppressor mutations is obtained and structural information is available, it is possible to generate detailed models of molecular function. However, the laborious and expensive task of identifying suppressor mutations in whole-genome selections limits the utility of this approach. Here I show that a custom targeted sequencing panel can greatly accelerate the identification of suppressor mutations in the Saccharomyces cerevisiae genome. Using a panel that targets 112 genes encoding pre-mRNA splicing factors, I identified 27 unique mutations in six protein-coding genes that each overcome the cold-sensitive block to spliceosome activation caused by a substitution in U4 small nuclear RNA. When mapped to existing structures of spliceosomal complexes, the identified suppressors implicate specific molecular contacts between the proteins Brr2, Prp6, Prp8, Prp31, Sad1, and Snu114 as functionally important in an early step of catalytic activation of the spliceosome. This approach shows great promise for elucidating the allosteric cascade of molecular interactions that direct accurate and efficient pre-mRNA splicing and should be broadly useful for understanding the dynamics of other complex biological assemblies or pathways.
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DDX3 Participates in Translational Control of Inflammation Induced by Infections and Injuries. Mol Cell Biol 2018; 39:MCB.00285-18. [PMID: 30373933 DOI: 10.1128/mcb.00285-18] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 10/10/2018] [Indexed: 12/28/2022] Open
Abstract
Recent studies have suggested that DDX3 functions in antiviral innate immunity, but the underlying mechanism remains elusive. We previously identified target mRNAs whose translation is controlled by DDX3. Pathway enrichment analysis of these targets indicated that DDX3 is involved in various infections and inflammation. Using immunoblotting, we confirmed that PACT, STAT1, GNB2, Rac1, TAK1, and p38 mitogen-activated protein kinase (MAPK) proteins are downregulated by DDX3 knockdown in human monocytic THP-1 cells and epithelial HeLa cells. Polysome profiling revealed that DDX3 knockdown reduces the translational efficiency of target mRNAs. We further demonstrated DDX3-mediated translational control of target mRNAs by luciferase reporter assays. To examine the effects of DDX3 knockdown on macrophage migration and phagocytosis, we performed in vitro cell migration assay and flow cytometry analysis of the uptake of green fluorescent protein-expressing Escherichia coli in THP-1 cells. The DDX3 knockdown cells exhibited impaired macrophage migration and phagocytosis. Moreover, we used a human cytokine antibody array to identify the cytokines affected by DDX3 knockdown. Several chemokines were decreased considerably in DDX3 knockdown THP-1 cells after lipopolysaccharide or poly(I·C) stimulation. Lastly, we demonstrated that DDX3 is crucial for the recruitment of phagocytes to the site of inflammation in transgenic zebrafish.
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Zhou C, Gao X, Hu S, Gan W, Xu J, Ma YC, Ma L. RBM-5 modulates U2AF large subunit-dependent alternative splicing in C. elegans. RNA Biol 2018; 15:1295-1308. [PMID: 30295127 PMCID: PMC6284560 DOI: 10.1080/15476286.2018.1526540] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Revised: 08/23/2018] [Accepted: 09/11/2018] [Indexed: 01/06/2023] Open
Abstract
A key step in pre-mRNA splicing is the recognition of 3' splicing sites by the U2AF large and small subunits, a process regulated by numerous trans-acting splicing factors. How these trans-acting factors interact with U2AF in vivo is unclear. From a screen for suppressors of the temperature-sensitive (ts) lethality of the C. elegans U2AF large subunit gene uaf-1(n4588) mutants, we identified mutations in the RNA binding motif gene rbm-5, a homolog of the tumor suppressor gene RBM5. rbm-5 mutations can suppress uaf-1(n4588) ts-lethality by loss of function and neuronal expression of rbm-5 was sufficient to rescue the suppression. Transcriptome analyses indicate that uaf-1(n4588) affected the expression of numerous genes and rbm-5 mutations can partially reverse the abnormal gene expression to levels similar to that of wild type. Though rbm-5 mutations did not obviously affect alternative splicing per se, they can suppress or enhance, in a gene-specific manner, the altered splicing of genes in uaf-1(n4588) mutants. Specifically, the recognition of a weak 3' splice site was more susceptible to the effect of rbm-5. Our findings provide novel in vivo evidence that RBM-5 can modulate UAF-1-dependent RNA splicing and suggest that RBM5 might interact with U2AF large subunit to affect tumor formation.
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Affiliation(s)
- Chuanman Zhou
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan, China
| | - Xiaoyang Gao
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan, China
| | - Surong Hu
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan, China
| | - Wenjing Gan
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan, China
| | - Jing Xu
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan, China
| | - Yongchao C. Ma
- Departments of Pediatrics, Neurology and Physiology, Northwestern University Feinberg School of Medicine, Anne & Robert H. Lurie Children’s Hospital of Chicago, Chicago, Illinois, USA
| | - Long Ma
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan, China
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7
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Vindry C, Marnef A, Broomhead H, Twyffels L, Ozgur S, Stoecklin G, Llorian M, Smith CW, Mata J, Weil D, Standart N. Dual RNA Processing Roles of Pat1b via Cytoplasmic Lsm1-7 and Nuclear Lsm2-8 Complexes. Cell Rep 2018; 20:1187-1200. [PMID: 28768202 PMCID: PMC5554784 DOI: 10.1016/j.celrep.2017.06.091] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 05/12/2017] [Accepted: 06/28/2017] [Indexed: 12/16/2022] Open
Abstract
Pat1 RNA-binding proteins, enriched in processing bodies (P bodies), are key players in cytoplasmic 5' to 3' mRNA decay, activating decapping of mRNA in complex with the Lsm1-7 heptamer. Using co-immunoprecipitation and immunofluorescence approaches coupled with RNAi, we provide evidence for a nuclear complex of Pat1b with the Lsm2-8 heptamer, which binds to the spliceosomal U6 small nuclear RNA (snRNA). Furthermore, we establish the set of interactions connecting Pat1b/Lsm2-8/U6 snRNA/SART3 and additional U4/U6.U5 tri-small nuclear ribonucleoprotein particle (tri-snRNP) components in Cajal bodies, the site of snRNP biogenesis. RNA sequencing following Pat1b depletion revealed the preferential upregulation of mRNAs normally found in P bodies and enriched in 3' UTR AU-rich elements. Changes in >180 alternative splicing events were also observed, characterized by skipping of regulated exons with weak donor sites. Our data demonstrate the dual role of a decapping enhancer in pre-mRNA processing as well as in mRNA decay via distinct nuclear and cytoplasmic Lsm complexes.
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Affiliation(s)
- Caroline Vindry
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK
| | - Aline Marnef
- LBCMCP, Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse UT3, 31062 Toulouse, France
| | - Helen Broomhead
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK
| | - Laure Twyffels
- Center for Microscopy and Molecular Imaging (CMMI), Université libre de Bruxelles (ULB), 6041 Gosselies, Belgium
| | - Sevim Ozgur
- Max Planck Institute of Biochemistry, Am Klopferspitz, 82152 Martinsried, Germany
| | - Georg Stoecklin
- Division of Biochemistry, Center for Biomedicine and Medical Technology Mannheim, Medical Faculty Mannheim, Heidelberg University, 69047 Heidelberg, Germany; Center for Molecular Biology of Heidelberg University (ZMBH), 69047 Heidelberg, Germany; German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, 68167 Mannheim, Germany
| | - Miriam Llorian
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK
| | - Christopher W Smith
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK
| | - Juan Mata
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK
| | - Dominique Weil
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, Biologie du développement Paris Seine - Institut de Biologie Paris Seine (LBD - IBPS), 75005 Paris, France
| | - Nancy Standart
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK.
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8
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Jung Y, Kim HD, Yang HW, Kim HJ, Jang CY, Kim J. Modulating cellular balance of Rps3 mono-ubiquitination by both Hel2 E3 ligase and Ubp3 deubiquitinase regulates protein quality control. Exp Mol Med 2017; 49:e390. [PMID: 29147007 PMCID: PMC5704183 DOI: 10.1038/emm.2017.128] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 03/25/2017] [Accepted: 03/27/2017] [Indexed: 12/14/2022] Open
Abstract
When a ribosome complex is stalled during the translation elongation process in eukaryotes, the mono-ubiquitination of Rps3 has recently been shown to be critical to ribosome quality control. We have discovered that the regulatory role of Rps3 mono-ubiquitination is controlled by a deubiquitinase. We also showed that an autophagic signal appears to be coupled to the mono-ubiquitination of Rps3p through the entrance of Ubp3p into the autophagosome in yeasts. The mono-ubiquitination of the Rps3 protein is tightly modulated by reciprocal action between the Hel2p E3 ligase and the Ubp3p deubiquitinase in yeasts and the reciprocal action between the RNF123 E3 ligase and the USP10 deubiquitinase in mammalian cells. We also found that the Ubp3p/USP10 deubiquitinases critically modulate Hel2p/RNF123-mediated Rps3p mono-ubiquitination. In addition, we found that Hel2p/RNF123 and Ubp3p/USP10 appeared to be differently localized in the ribosome complex after ultraviolet irradiation. Together, our results support a model in which coordinated ubiquitination and deubiquitination activities can finely balance the level of regulatory Rps3p mono-ubiquitination in ribosome-associated quality control and autophagy processes.
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Affiliation(s)
- Youjin Jung
- Laboratory of Biochemistry, Division of Life Sciences, Korea University, Seoul, Republic of Korea
| | - Hag Dong Kim
- Laboratory of Biochemistry, Division of Life Sciences, Korea University, Seoul, Republic of Korea.,HAEL Lab, TechnoComplex Building 603-3, Korea University, Seoul, Republic of Korea
| | - Hee Woong Yang
- Laboratory of Biochemistry, Division of Life Sciences, Korea University, Seoul, Republic of Korea
| | - Hye Jin Kim
- Laboratory of Biochemistry, Division of Life Sciences, Korea University, Seoul, Republic of Korea
| | - Chang-Young Jang
- Laboratory of Cell Biology, Research Center for Cell Fate Control, College of Pharmacy, Sookmyung Women's University, Seoul, Republic of Korea
| | - Joon Kim
- Laboratory of Biochemistry, Division of Life Sciences, Korea University, Seoul, Republic of Korea.,HAEL Lab, TechnoComplex Building 603-3, Korea University, Seoul, Republic of Korea
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Sperling J, Sperling R. Structural studies of the endogenous spliceosome - The supraspliceosome. Methods 2017; 125:70-83. [PMID: 28412289 PMCID: PMC5546952 DOI: 10.1016/j.ymeth.2017.04.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Revised: 04/01/2017] [Accepted: 04/10/2017] [Indexed: 12/17/2022] Open
Abstract
Pre-mRNA splicing is executed in mammalian cell nuclei within a huge (21MDa) and highly dynamic molecular machine - the supraspliceosome - that individually package pre-mRNA transcripts of different sizes and number of introns into complexes of a unique structure, indicating their universal nature. Detailed structural analysis of this huge and complex structure requires a stepwise approach using hybrid methods. Structural studies of the supraspliceosome by room temperature electron tomography, cryo-electron tomography, and scanning transmission electron microscope mass measurements revealed that it is composed of four native spliceosomes, each resembling an in vitro assembled spliceosome, which are connected by the pre-mRNA. It also elucidated the arrangement of the native spliceosomes within the intact supraspliceosome. Native spliceosomes and supraspliceosomes contain all five spliceosomal U snRNPs together with other splicing factors, and are active in splicing. The structure of the native spliceosome, at a resolution of 20Å, was determined by cryo-electron microscopy, and a unique spatial arrangement of the spliceosomal U snRNPs within the native spliceosome emerged from in silico studies. The supraspliceosome also harbor components for all pre-mRNA processing activities. Thus the supraspliceosome - the endogenous spliceosome - is a stand-alone complete macromolecular machine capable of performing splicing, alternative splicing, and encompass all nuclear pre-mRNA processing activities that the pre-mRNA has to undergo before it can exit from the nucleus to the cytoplasm to encode for protein. Further high-resolution cryo-electron microscopy studies of the endogenous spliceosome are required to decipher the regulation of alternative splicing, and elucidate the network of processing activities within it.
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Affiliation(s)
- Joseph Sperling
- Department of Organic Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Ruth Sperling
- Department of Genetics, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
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10
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Kim YD, Lee J, Kim HS, Lee MO, Son MY, Yoo CH, Choi JK, Lee SC, Cho YS. The unique spliceosome signature of human pluripotent stem cells is mediated by SNRPA1, SNRPD1, and PNN. Stem Cell Res 2017; 22:43-53. [PMID: 28595116 DOI: 10.1016/j.scr.2017.05.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 05/25/2017] [Accepted: 05/26/2017] [Indexed: 12/21/2022] Open
Abstract
Spliceosomes are the core host of pre-mRNA splicing, allowing multiple protein isoforms to be produced from a single gene. Herein, we reveal that spliceosomes are more abundant in human pluripotent stem cells (hPSs), including human embryonic stem cells (hESs) and human induced pluripotent stem cells (hiPSs), than non-hPSs, and their presence is associated with high transcriptional activity. Supportively, spliceosomal components involved in the catalytically active pre-mRNA splicing step were mainly co-localized with hPS spliceosomes. By profiling the gene expression of 342 selected splicing factors, we found that 71 genes were significantly altered during the reprogramming of human somatic cells into hiPSs. Among them, SNRPA1, SNRPD1, and PNN were significantly up-regulated during the early stage of reprogramming, identified as hub genes by interaction network and cluster analysis. SNRPA1, SNRPD1, or PNN depletion led to a pronounced loss of pluripotency and significantly blocked hiPS generation. SNRPA1, SNRPD1, and PNN co-localized with the hPS spliceosomes, physically interacted with each other, and positively influenced the appearance of hPS spliceosomes. Our data suggest that SNRPA1, SNRPD1, and PNN are key players in the regulation of pluripotency-specific spliceosome assembly and the acquisition and maintenance of pluripotency.
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Affiliation(s)
- Young-Dae Kim
- Stem Cell Research Laboratory, Immunotherapy Convergence Research Center, Korea Research Institute of Bioscience and Biotechnology, 125 Gwahak-ro, Yuseong-gu, Daejeon, Republic of Korea
| | - Jungwoon Lee
- Stem Cell Research Laboratory, Immunotherapy Convergence Research Center, Korea Research Institute of Bioscience and Biotechnology, 125 Gwahak-ro, Yuseong-gu, Daejeon, Republic of Korea
| | - Han-Seop Kim
- Stem Cell Research Laboratory, Immunotherapy Convergence Research Center, Korea Research Institute of Bioscience and Biotechnology, 125 Gwahak-ro, Yuseong-gu, Daejeon, Republic of Korea
| | - Mi-Ok Lee
- Stem Cell Research Laboratory, Immunotherapy Convergence Research Center, Korea Research Institute of Bioscience and Biotechnology, 125 Gwahak-ro, Yuseong-gu, Daejeon, Republic of Korea
| | - Mi-Young Son
- Stem Cell Research Center, Korea Research Institute of Bioscience and Biotechnology, 125 Gwahak-ro, Yuseong-gu, Daejeon, Republic of Korea
| | - Chae Hwa Yoo
- Stem Cell Research Laboratory, Immunotherapy Convergence Research Center, Korea Research Institute of Bioscience and Biotechnology, 125 Gwahak-ro, Yuseong-gu, Daejeon, Republic of Korea
| | - Jung-Kyun Choi
- Stem Cell Research Laboratory, Immunotherapy Convergence Research Center, Korea Research Institute of Bioscience and Biotechnology, 125 Gwahak-ro, Yuseong-gu, Daejeon, Republic of Korea; Department of Bioscience, KRIBB School, University of Science & Technology, 113 Gwahak-ro, Yuseong-gu, Daejeon 34113, Republic of Korea
| | - Sang Chul Lee
- Research Center for Metabolic Regulation, Korea Research Institute of Bioscience and Biotechnology, 125 Gwahak-ro, Yuseong-gu, Daejeon, Republic of Korea
| | - Yee Sook Cho
- Stem Cell Research Laboratory, Immunotherapy Convergence Research Center, Korea Research Institute of Bioscience and Biotechnology, 125 Gwahak-ro, Yuseong-gu, Daejeon, Republic of Korea; Department of Bioscience, KRIBB School, University of Science & Technology, 113 Gwahak-ro, Yuseong-gu, Daejeon 34113, Republic of Korea.
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11
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Yan J, Kang C, Bian Z, Jin R, Ma X, Gao L. Supramolecular self-assembly of chiral polyimides driven by repeat units and end groups. NEW J CHEM 2017. [DOI: 10.1039/c7nj02451g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Complementary aromatic π–π stacking and hydrogen bonding induce time-dependent chiroptical spectroscopic behaviours of l-phenylalaninate-derived chiral polyimide.
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Affiliation(s)
- Jijun Yan
- State Key Laboratory of Polymer Physics and Chemistry
- Changchun Institute of Applied Chemistry
- Chinese Academy of Sciences
- Changchun 130022
- China
| | - Chuanqing Kang
- State Key Laboratory of Polymer Physics and Chemistry
- Changchun Institute of Applied Chemistry
- Chinese Academy of Sciences
- Changchun 130022
- China
| | - Zheng Bian
- State Key Laboratory of Polymer Physics and Chemistry
- Changchun Institute of Applied Chemistry
- Chinese Academy of Sciences
- Changchun 130022
- China
| | - Rizhe Jin
- State Key Laboratory of Polymer Physics and Chemistry
- Changchun Institute of Applied Chemistry
- Chinese Academy of Sciences
- Changchun 130022
- China
| | - Xiaoye Ma
- State Key Laboratory of Polymer Physics and Chemistry
- Changchun Institute of Applied Chemistry
- Chinese Academy of Sciences
- Changchun 130022
- China
| | - Lianxun Gao
- State Key Laboratory of Polymer Physics and Chemistry
- Changchun Institute of Applied Chemistry
- Chinese Academy of Sciences
- Changchun 130022
- China
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12
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Das S, Das B. eIF4G—an integrator of mRNA metabolism? FEMS Yeast Res 2016; 16:fow087. [DOI: 10.1093/femsyr/fow087] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/29/2016] [Indexed: 11/14/2022] Open
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13
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Sperling R. The nuts and bolts of the endogenous spliceosome. WILEY INTERDISCIPLINARY REVIEWS-RNA 2016; 8. [PMID: 27465259 DOI: 10.1002/wrna.1377] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 06/14/2016] [Accepted: 06/15/2016] [Indexed: 01/09/2023]
Abstract
The complex life of pre-mRNA from transcription to the production of mRNA that can be exported from the nucleus to the cytoplasm to encode for proteins entails intricate coordination and regulation of a network of processing events. Coordination is required between transcription and splicing and between several processing events including 5' and 3' end processing, splicing, alternative splicing and editing that are major contributors to the diversity of the human proteome, and occur within a huge and dynamic macromolecular machine-the endogenous spliceosome. Detailed mechanistic insight of the splicing reaction was gained from studies of the in vitro spliceosome assembled on a single intron. Because most pre-mRNAs are multiintronic that undergo alternative splicing, the in vivo splicing machine requires additional elements to those of the in vitro machine, to account for all these diverse functions. Information about the endogenous spliceosome is emerging from imaging studies in intact and live cells that support the cotranscriptional commitment to splicing model and provide information about splicing kinetics in vivo. Another source comes from studies of the in vivo assembled spliceosome, isolated from cell nuclei under native conditions-the supraspliceosome-that individually package pre-mRNA transcripts of different sizes and number of introns into complexes of a unique structure, indicating their universal nature. Recent years have portrayed new players affecting alternative splicing and novel connections between splicing, transcription and chromatin. The challenge ahead is to elucidate the structure and function of the endogenous spliceosome and decipher the regulation and coordination of its network of processing activities. WIREs RNA 2017, 8:e1377. doi: 10.1002/wrna.1377 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Ruth Sperling
- Department of Genetics, The Hebrew University of Jerusalem, Jerusalem, Israel
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14
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Meyer F. Viral interactions with components of the splicing machinery. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2016; 142:241-68. [PMID: 27571697 DOI: 10.1016/bs.pmbts.2016.05.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Eukaryotic genes are often interrupted by stretches of sequence with no protein coding potential or obvious function. After transcription, these interrupting sequences must be removed to give rise to the mature messenger RNA. This fundamental process is called RNA splicing and is achieved by complicated machinery made of protein and RNA that assembles around the RNA to be edited. Viruses also use RNA splicing to maximize their coding potential and economize on genetic space, and use clever strategies to manipulate the splicing machinery to their advantage. This article gives an overview of the splicing process and provides examples of viral strategies that make use of various components of the splicing system to promote their replicative cycle. Representative virus families have been selected to illustrate the interaction with various regulatory proteins and ribonucleoproteins. The unifying theme is fine regulation through protein-protein and protein-RNA interactions with the spliceosome components and associated factors to promote or prevent spliceosome assembly on given splice sites, in addition to a strong influence from cis-regulatory sequences on viral transcripts. Because there is an intimate coupling of splicing with the processes that direct mRNA biogenesis, a description of how these viruses couple the regulation of splicing with the retention or stability of mRNAs is also included. It seems that a unique balance of suppression and activation of splicing and nuclear export works optimally for each family of viruses.
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Affiliation(s)
- F Meyer
- Department of Biochemistry & Molecular Biology, Entomology & Plant Pathology, Mississippi State University, Starkville, MS, USA.
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15
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Valentin-Vega YA, Wang YD, Parker M, Patmore DM, Kanagaraj A, Moore J, Rusch M, Finkelstein D, Ellison DW, Gilbertson RJ, Zhang J, Kim HJ, Taylor JP. Cancer-associated DDX3X mutations drive stress granule assembly and impair global translation. Sci Rep 2016; 6:25996. [PMID: 27180681 PMCID: PMC4867597 DOI: 10.1038/srep25996] [Citation(s) in RCA: 109] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 04/21/2016] [Indexed: 12/26/2022] Open
Abstract
DDX3X is a DEAD-box RNA helicase that has been implicated in multiple aspects of RNA metabolism including translation initiation and the assembly of stress granules (SGs). Recent genomic studies have reported recurrent DDX3X mutations in numerous tumors including medulloblastoma (MB), but the physiological impact of these mutations is poorly understood. Here we show that a consistent feature of MB-associated mutations is SG hyper-assembly and concomitant translation impairment. We used CLIP-seq to obtain a comprehensive assessment of DDX3X binding targets and ribosome profiling for high-resolution assessment of global translation. Surprisingly, mutant DDX3X expression caused broad inhibition of translation that impacted DDX3X targeted and non-targeted mRNAs alike. Assessment of translation efficiency with single-cell resolution revealed that SG hyper-assembly correlated precisely with impaired global translation. SG hyper-assembly and translation impairment driven by mutant DDX3X were rescued by a genetic approach that limited SG assembly and by deletion of the N-terminal low complexity domain within DDX3X. Thus, in addition to a primary defect at the level of translation initiation caused by DDX3X mutation, SG assembly itself contributes to global translation inhibition. This work provides mechanistic insights into the consequences of cancer-related DDX3X mutations, suggesting that globally reduced translation may provide a context-dependent survival advantage that must be considered as a possible contributor to tumorigenesis.
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Affiliation(s)
- Yasmine A. Valentin-Vega
- Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
| | - Yong-Dong Wang
- Department of Computational Biology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
| | - Matthew Parker
- Department of Computational Biology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
| | - Deanna M. Patmore
- Department of Oncology, Cambridge Cancer Centre, Cancer Research UK Cambridge Institute, Cambridge, UK
| | - Anderson Kanagaraj
- Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
| | - Jennifer Moore
- Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
| | - Michael Rusch
- Department of Computational Biology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
| | - David Finkelstein
- Department of Computational Biology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
| | - David W. Ellison
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
| | - Richard J. Gilbertson
- Department of Oncology, Cambridge Cancer Centre, Cancer Research UK Cambridge Institute, Cambridge, UK
| | - Jinghui Zhang
- Department of Computational Biology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
| | - Hong Joo Kim
- Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
| | - J. Paul Taylor
- Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
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16
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Haudek KC, Voss PG, Wang JL, Patterson RJ. A 10S galectin-3-U1 snRNP complex assembles into active spliceosomes. Nucleic Acids Res 2016; 44:6391-7. [PMID: 27105840 PMCID: PMC5291251 DOI: 10.1093/nar/gkw303] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 04/12/2016] [Indexed: 12/13/2022] Open
Abstract
In previous studies, we reported that fractionation of HeLa cell nuclear extracts on glycerol gradients revealed an endogenous ∼10S particle that contained galectin-3 and U1 snRNP and this particle was sufficient to load the galectin polypeptide onto a pre-mRNA substrate. We now document that this interaction between the galectin-3–U1 snRNP particle and the pre-mRNA results in a productive spliceosomal complex, leading to intermediates and products of the splicing reaction. Nuclear extracts were depleted of U1 snRNP with a concomitant loss of splicing activity. Splicing activity in the U1-depleted extract can be reconstituted by the galectin-3–U1 snRNP particle, isolated by immunoprecipitation of the 10S region (fractions 3–5) of the glycerol gradient with anti-galectin-3 antibodies. In contrast, parallel anti-galectin-3 immunoprecipitation of free galectin-3 molecules not in a complex with U1 snRNP (fraction 1 of the same gradient), failed to restore splicing activity. These results indicate that the galectin-3–U1 snRNP-pre-mRNA ternary complex is a functional E complex and that U1 snRNP is required to assemble galectin-3 onto an active spliceosome.
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Affiliation(s)
- Kevin C Haudek
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA
| | - Patricia G Voss
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA
| | - John L Wang
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA
| | - Ronald J Patterson
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA
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17
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Lo PK, Huang YC, Poulton JS, Leake N, Palmer WH, Vera D, Xie G, Klusza S, Deng WM. RNA helicase Belle/DDX3 regulates transgene expression in Drosophila. Dev Biol 2016; 412:57-70. [PMID: 26900887 DOI: 10.1016/j.ydbio.2016.02.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 02/10/2016] [Accepted: 02/16/2016] [Indexed: 11/28/2022]
Abstract
Belle (Bel), the Drosophila homolog of the yeast DEAD-box RNA helicase DED1 and human DDX3, has been shown to be required for oogenesis and female fertility. Here we report a novel role of Bel in regulating the expression of transgenes. Abrogation of Bel by mutations or RNAi induces silencing of a variety of P-element-derived transgenes. This silencing effect depends on downregulation of their RNA levels. Our genetic studies have revealed that the RNA helicase Spindle-E (Spn-E), a nuage RNA helicase that plays a crucial role in regulating RNA processing and PIWI-interacting RNA (piRNA) biogenesis in germline cells, is required for loss-of-bel-induced transgene silencing. Conversely, Bel abrogation alleviates the nuage-protein mislocalization phenotype in spn-E mutants, suggesting a competitive relationship between these two RNA helicases. Additionally, disruption of the chromatin remodeling factor Mod(mdg4) or the microRNA biogenesis enzyme Dicer-1 (Dcr-1) also alleviates the transgene-silencing phenotypes in bel mutants, suggesting the involvement of chromatin remodeling and microRNA biogenesis in loss-of-bel-induced transgene silencing. Finally we show that genetic inhibition of Bel function leads to de novo generation of piRNAs from the transgene region inserted in the genome, suggesting a potential piRNA-dependent mechanism that may mediate transgene silencing as Bel function is inhibited.
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Affiliation(s)
- Pang-Kuo Lo
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
| | - Yi-Chun Huang
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
| | - John S Poulton
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
| | - Nicholas Leake
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
| | - William H Palmer
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
| | - Daniel Vera
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
| | - Gengqiang Xie
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
| | - Stephen Klusza
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
| | - Wu-Min Deng
- Department of Biological Science, Florida State University, Tallahassee, FL, USA.
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18
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Lai MC, Sun HS, Wang SW, Tarn WY. DDX3 functions in antiviral innate immunity through translational control of PACT. FEBS J 2015; 283:88-101. [PMID: 26454002 PMCID: PMC7164078 DOI: 10.1111/febs.13553] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Revised: 09/10/2015] [Accepted: 10/06/2015] [Indexed: 01/14/2023]
Abstract
It has emerged that DDX3 plays a role in antiviral innate immunity. However, the exact mechanism by which DDX3 functions in antiviral innate immunity remains to be determined. We found that the expression of the protein activator of the interferon‐induced protein kinase (PACT) was regulated by DDX3 in human cells. PACT acts as a cellular activator of retinoic acid‐inducible gene‐I‐like receptors in the sensing of viral RNAs. DDX3 facilitated the translation of PACT mRNA that may contain a structured 5′ UTR. Knockdown of DDX3 decreased the viral RNA detection sensitivity of the cells. PACT partially rescued defects of interferon‐β1 and chemokine (C‐C motif) ligand 5/RANTES (regulated on activation normal T cell expressed and secreted) induction in DDX3‐knockdown HEK293 cells. Therefore, DDX3 may participate in antiviral innate immunity, at least in part, by translational control of PACT. Moreover, we show that overexpression of the hepatitis C virus (HCV) core protein inhibited the translation of a reporter mRNA harboring the PACT 5′ UTR. The HCV core protein was associated and colocalized with DDX3 in cytoplasmic stress granules, suggesting that the HCV core may abrogate the function of DDX3 by sequestering DDX3 in stress granules. The perturbation of DDX3 by viral proteins delineates a critical role for DDX3 in antiviral host defense.
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Affiliation(s)
- Ming-Chih Lai
- Department of Biomedical Sciences, Chang Gung University, Taoyuan, Taiwan
| | - H Sunny Sun
- Institute of Molecular Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Shainn-Wei Wang
- Institute of Molecular Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Woan-Yuh Tarn
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
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19
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Bish R, Cuevas-Polo N, Cheng Z, Hambardzumyan D, Munschauer M, Landthaler M, Vogel C. Comprehensive Protein Interactome Analysis of a Key RNA Helicase: Detection of Novel Stress Granule Proteins. Biomolecules 2015; 5:1441-66. [PMID: 26184334 PMCID: PMC4598758 DOI: 10.3390/biom5031441] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2015] [Accepted: 06/15/2015] [Indexed: 12/24/2022] Open
Abstract
DDX6 (p54/RCK) is a human RNA helicase with central roles in mRNA decay and translation repression. To help our understanding of how DDX6 performs these multiple functions, we conducted the first unbiased, large-scale study to map the DDX6-centric protein-protein interactome using immunoprecipitation and mass spectrometry. Using DDX6 as bait, we identify a high-confidence and high-quality set of protein interaction partners which are enriched for functions in RNA metabolism and ribosomal proteins. The screen is highly specific, maximizing the number of true positives, as demonstrated by the validation of 81% (47/58) of the RNA-independent interactors through known functions and interactions. Importantly, we minimize the number of indirect interaction partners through use of a nuclease-based digestion to eliminate RNA. We describe eleven new interactors, including proteins involved in splicing which is an as-yet unknown role for DDX6. We validated and characterized in more detail the interaction of DDX6 with Nuclear fragile X mental retardation-interacting protein 2 (NUFIP2) and with two previously uncharacterized proteins, FAM195A and FAM195B (here referred to as granulin-1 and granulin-2, or GRAN1 and GRAN2). We show that NUFIP2, GRAN1, and GRAN2 are not P-body components, but re-localize to stress granules upon exposure to stress, suggesting a function in translation repression in the cellular stress response. Using a complementary analysis that resolved DDX6's multiple complex memberships, we further validated these interaction partners and the presence of splicing factors. As DDX6 also interacts with the E3 SUMO ligase TIF1β, we tested for and observed a significant enrichment of sumoylation amongst DDX6's interaction partners. Our results represent the most comprehensive screen for direct interaction partners of a key regulator of RNA life cycle and localization, highlighting new stress granule components and possible DDX6 functions-many of which are likely conserved across eukaryotes.
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Affiliation(s)
- Rebecca Bish
- Center for Genomics and Systems Biology, Department of Biology, New York University, 12 Waverly Place, New York, NY 10003, USA.
| | - Nerea Cuevas-Polo
- Center for Genomics and Systems Biology, Department of Biology, New York University, 12 Waverly Place, New York, NY 10003, USA.
| | - Zhe Cheng
- Center for Genomics and Systems Biology, Department of Biology, New York University, 12 Waverly Place, New York, NY 10003, USA.
| | - Dolores Hambardzumyan
- The Cleveland Clinic, Department of Neurosciences, Lerner Research Institute, 9500 Euclid Avenue, Cleveland, OH 44195, USA.
| | - Mathias Munschauer
- RNA Biology and Post-Transcriptional Regulation, Max-Delbrück-Center for Molecular Medicine, Berlin-Buch, Robert-Rössle-Str. 10, Berlin 13092, Germany.
| | - Markus Landthaler
- RNA Biology and Post-Transcriptional Regulation, Max-Delbrück-Center for Molecular Medicine, Berlin-Buch, Robert-Rössle-Str. 10, Berlin 13092, Germany.
| | - Christine Vogel
- Center for Genomics and Systems Biology, Department of Biology, New York University, 12 Waverly Place, New York, NY 10003, USA.
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20
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Hauk G, Bowman GD. Formation of a Trimeric Xpo1-Ran[GTP]-Ded1 Exportin Complex Modulates ATPase and Helicase Activities of Ded1. PLoS One 2015; 10:e0131690. [PMID: 26120835 PMCID: PMC4484809 DOI: 10.1371/journal.pone.0131690] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Accepted: 06/05/2015] [Indexed: 11/24/2022] Open
Abstract
The DEAD-box RNA helicase Ded1, which is essential in yeast and known as DDX3 in humans, shuttles between the nucleus and cytoplasm and takes part in several basic processes including RNA processing and translation. A key interacting partner of Ded1 is the exportin Xpo1, which together with the GTP-bound state of the small GTPase Ran, facilitates unidirectional transport of Ded1 out of the nucleus. Here we demonstrate that Xpo1 and Ran[GTP] together reduce the RNA-stimulated ATPase and helicase activities of Ded1. Binding and inhibition of Ded1 by Xpo1 depend on the affinity of the Ded1 nuclear export sequence (NES) for Xpo1 and the presence of Ran[GTP]. Association with Xpo1/Ran[GTP] reduces RNA-stimulated ATPase activity of Ded1 by increasing the apparent KM for the RNA substrate. Despite the increased KM, the Ded1:Xpo1:Ran[GTP] ternary complex retains the ability to bind single stranded RNA, suggesting that Xpo1/Ran[GTP] may modulate the substrate specificity of Ded1. These results demonstrate that, in addition to transport, exportins such as Xpo1 also have the capability to alter enzymatic activities of their cargo.
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Affiliation(s)
- Glenn Hauk
- T.C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Gregory D. Bowman
- T.C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, Maryland, United States of America
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21
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Rodgers ML, Paulson J, Hoskins AA. Rapid isolation and single-molecule analysis of ribonucleoproteins from cell lysate by SNAP-SiMPull. RNA (NEW YORK, N.Y.) 2015; 21:1031-41. [PMID: 25805862 PMCID: PMC4408783 DOI: 10.1261/rna.047845.114] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Accepted: 02/03/2015] [Indexed: 05/08/2023]
Abstract
Large macromolecular complexes such as the spliceosomal small nuclear ribonucleoproteins (snRNPs) play a variety of roles within the cell. Despite their biological importance, biochemical studies of snRNPs and other machines are often thwarted by practical difficulties in the isolation of sufficient amounts of material. Studies of the snRNPs as well as other macromolecular machines would be greatly facilitated by new approaches that enable their isolation and biochemical characterization. One such approach is single-molecule pull-down (SiMPull) that combines in situ immunopurification of complexes from cell lysates with subsequent single-molecule fluorescence microscopy experiments. We report the development of a new method, called SNAP-SiMPull, that can readily be applied to studies of splicing factors and snRNPs isolated from whole-cell lysates. SNAP-SiMPull overcomes many of the limitations imposed by conventional SiMPull strategies that rely on fluorescent proteins. We have used SNAP-SiMPull to study the yeast branchpoint bridging protein (BBP) as well as the U1 and U6 snRNPs. SNAP-SiMPull will likely find broad use for rapidly isolating complex cellular machines for single-molecule fluorescence colocalization experiments.
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Affiliation(s)
- Margaret L Rodgers
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706, USA
| | - Joshua Paulson
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706, USA
| | - Aaron A Hoskins
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706, USA
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22
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Abstract
The human spliceosome is a large ribonucleoprotein complex that catalyzes pre-mRNA splicing. It consists of five snRNAs and more than 200 proteins. Because of this complexity, much work has focused on the Saccharomyces cerevisiae spliceosome, viewed as a highly simplified system with fewer than half as many splicing factors as humans. Nevertheless, it has been difficult to ascribe a mechanistic function to individual splicing factors or even to discern which are critical for catalyzing the splicing reaction. We have identified and characterized the splicing machinery from the red alga Cyanidioschyzon merolae, which has been reported to harbor only 26 intron-containing genes. The U2, U4, U5, and U6 snRNAs contain expected conserved sequences and have the ability to adopt secondary structures and form intermolecular base-pairing interactions, as in other organisms. C. merolae has a highly reduced set of 43 identifiable core splicing proteins, compared with ∼90 in budding yeast and ∼140 in humans. Strikingly, we have been unable to find a U1 snRNA candidate or any predicted U1-associated proteins, suggesting that splicing in C. merolae may occur without the U1 small nuclear ribonucleoprotein particle. In addition, based on mapping the identified proteins onto the known splicing cycle, we propose that there is far less compositional variability during splicing in C. merolae than in other organisms. The observed reduction in splicing factors is consistent with the elimination of spliceosomal components that play a peripheral or modulatory role in splicing, presumably retaining those with a more central role in organization and catalysis.
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23
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Abstract
In eukaryotic organisms, the orthologs of the DEAD-box RNA helicase Ded1p from yeast and DDX3 from human form a well-defined subfamily that is characterized by high sequence conservation in their helicase core and their N- and C- termini. Individual members of this Ded1/DDX3 subfamily perform multiple functions in RNA metabolism in both nucleus and cytoplasm. Ded1/DDX3 subfamily members have also been implicated in cellular signaling pathways and are targeted by diverse viruses. In this review, we discuss the considerable body of work on the biochemistry and biology of these proteins, including the recently discovered link of human DDX3 to tumorigenesis.
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Affiliation(s)
- Deepak Sharma
- Center for RNA Molecular Biology & Department of Biochemistry, School of Medicine, Case Western Reserve University , Cleveland, OH , USA
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24
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Zhang L, Li X, Hill RC, Qiu Y, Zhang W, Hansen KC, Zhao R. Brr2 plays a role in spliceosomal activation in addition to U4/U6 unwinding. Nucleic Acids Res 2015; 43:3286-97. [PMID: 25670679 PMCID: PMC4381053 DOI: 10.1093/nar/gkv062] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2014] [Accepted: 01/19/2015] [Indexed: 12/22/2022] Open
Abstract
Brr2 is a DExD/H-box RNA helicase that is responsible for U4/U6 unwinding, a critical step in spliceosomal activation. Brr2 is a large protein (∼250 kD) that consists of an N-terminal domain (∼500 residues) with unknown function and two Hel308-like modules that are responsible for RNA unwinding. Here we demonstrate that removal of the entire N-terminal domain is lethal to Saccharomyces cerevisiae and deletion of the N-terminal 120 residues leads to splicing defects and severely impaired growth. This N-terminal truncation does not significantly affect Brr2's helicase activity. Brr2-Δ120 can be successfully assembled into the tri-snRNP (albeit at a lower level than the WT Brr2) and the spliceosomal B complex. However, the truncation significantly impairs spliceosomal activation, leading to a dramatic reduction of U5, U6 snRNAs and accumulation of U1 snRNA in the Bact complex. The N-terminal domain of Brr2 does not seem to be directly involved in regulating U1/5'ss unwinding. Instead, the N-terminal domain seems to be critical for retaining U5 and U6 snRNPs during/after spliceosomal activation through its interaction with snRNAs and possibly other spliceosomal proteins, revealing a new role of Brr2 in spliceosomal activation in addition to U4/U6 unwinding.
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Affiliation(s)
- Lingdi Zhang
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Xueni Li
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Ryan C Hill
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Yan Qiu
- College of Bioscience and Bioengineering, Hebei University of Science and Technology, Shijiazhuang 050018, P. R. China
| | - Wenzheng Zhang
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Kirk C Hansen
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Rui Zhao
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA
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25
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Collier SE, Voehler M, Peng D, Ohi R, Gould KL, Reiter NJ, Ohi MD. Structural and functional insights into the N-terminus of Schizosaccharomyces pombe Cdc5. Biochemistry 2014; 53:6439-51. [PMID: 25263959 PMCID: PMC4204884 DOI: 10.1021/bi5008639] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
![]()
The
spliceosome is a dynamic macromolecular machine composed of
five small nuclear ribonucleoparticles (snRNPs), the NineTeen Complex
(NTC), and other proteins that catalyze the removal of introns mature
to form the mature message. The NTC, named after its founding member Saccharomyces cerevisiae Prp19, is a conserved spliceosome
subcomplex composed of at least nine proteins. During spliceosome
assembly, the transition to an active spliceosome correlates with
stable binding of the NTC, although the mechanism of NTC function
is not understood. Schizosaccharomyces pombe Cdc5, a core subunit of the NTC, is an essential protein required
for pre-mRNA splicing. The highly conserved Cdc5 N-terminus contains
two canonical Myb (myeloblastosis) repeats (R1 and R2) and a third
domain (D3) that was previously classified as a Myb-like repeat. Although
the N-terminus of Cdc5 is required for its function, how R1, R2, and
D3 each contribute to functionality is unclear. Using a combination
of yeast genetics, structural approaches, and RNA binding assays,
we show that R1, R2, and D3 are all required for the function of Cdc5
in cells. We also show that the N-terminus of Cdc5 binds RNA in vitro. Structural and functional analyses of Cdc5-D3
show that, while this domain does not adopt a Myb fold, Cdc5-D3 preferentially
binds double-stranded RNA. Our data suggest that the Cdc5 N-terminus
interacts with RNA structures proposed to be near the catalytic core
of the spliceosome.
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Affiliation(s)
- Scott E Collier
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center , Nashville, Tennessee 37232, United States
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26
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Shefer K, Sperling J, Sperling R. The Supraspliceosome - A Multi-Task Machine for Regulated Pre-mRNA Processing in the Cell Nucleus. Comput Struct Biotechnol J 2014; 11:113-22. [PMID: 25408845 PMCID: PMC4232567 DOI: 10.1016/j.csbj.2014.09.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2014] [Revised: 09/16/2014] [Accepted: 09/18/2014] [Indexed: 01/23/2023] Open
Abstract
Pre-mRNA splicing of Pol II transcripts is executed in the mammalian cell nucleus within a huge (21 MDa) and highly dynamic RNP machine — the supraspliceosome. It is composed of four splicing active native spliceosomes, each resembling an in vitro assembled spliceosome, which are connected by the pre-mRNA. Supraspliceosomes harbor protein splicing factors and all the five-spliceosomal U snRNPs. Recent analysis of specific supraspliceosomes at defined splicing stages revealed that they harbor all five spliceosomal U snRNAs at all splicing stages. Supraspliceosomes harbor additional pre-mRNA processing components, such as the 5′-end and 3′-end processing components, and the RNA editing enzymes ADAR1 and ADAR2. The structure of the native spliceosome, at a resolution of 20 Å, was determined by cryo-EM. A unique spatial arrangement of the spliceosomal U snRNPs within the native spliceosome emerged from in-silico studies, localizing the five U snRNPs mostly within its large subunit, and sheltering the active core components deep within the spliceosomal cavity. The supraspliceosome provides a platform for coordinating the numerous processing steps that the pre-mRNA undergoes: 5′ and 3′-end processing activities, RNA editing, constitutive and alternative splicing, and processing of intronic microRNAs. It also harbors a quality control mechanism termed suppression of splicing (SOS) that, under normal growth conditions, suppresses splicing at abundant intronic latent 5′ splice sites in a reading frame-dependent fashion. Notably, changes in these regulatory processing activities are associated with human disease and cancer. These findings emphasize the supraspliceosome as a multi-task master regulator of pre-mRNA processing in the cell nucleus.
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Affiliation(s)
- Kinneret Shefer
- Department of Organic Chemistry, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Joseph Sperling
- Department of Organic Chemistry, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Ruth Sperling
- Department of Genetics, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
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Martínez-Salazar M, López-Urrutia E, Arechaga-Ocampo E, Bonilla-Moreno R, Martínez-Castillo M, Díaz-Hernández J, Del Moral-Hernández O, Cedillo-Barrón L, Martines-Juarez V, De Nova-Ocampo M, Valdes J, Berumen J, Villegas-Sepúlveda N. Biochemical and proteomic analysis of spliceosome factors interacting with intron-1 of human papillomavirus type-16. J Proteomics 2014; 111:184-97. [PMID: 25108200 DOI: 10.1016/j.jprot.2014.07.029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Revised: 06/21/2014] [Accepted: 07/28/2014] [Indexed: 01/16/2023]
Abstract
The human papillomavirus type 16 (HPV-16) E6/E7 spliced transcripts are heterogeneously expressed in cervical carcinoma. The heterogeneity of the E6/E7 splicing profile might be in part due to the intrinsic variation of splicing factors in tumor cells. However, the splicing factors that bind the E6/E7 intron 1 (In-1) have not been defined. Therefore, we aimed to identify these factors; we used HeLa nuclear extracts (NE) for in vitro spliceosome assembly. The proteins were allowed to bind to an RNA/DNA hybrid formed by the In-1 transcript and a 5'-biotinylated DNA oligonucleotide complementary to the upstream exon sequence, which prevented interference in protein binding to the intron. The hybrid probes bound with the nuclear proteins were coupled to streptavidin magnetic beads for chromatography affinity purification. Proteins were eluted and identified by mass spectrometry (MS). Approximately 170 proteins were identified by MS, 80% of which were RNA binding proteins, including canonical spliceosome core components, helicases and regulatory splicing factors. The canonical factors were identified as components of the spliceosomal B-complex. Although 35-40 of the identified factors were cognate splicing factors or helicases, they have not been previously detected in spliceosome complexes that were assembled using in vivo or in vitro models.
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Affiliation(s)
- Martha Martínez-Salazar
- Departamento de Biomedicina Molecular, Centro de Investigación y de Estudios Avanzados (CINVESTAV) Apdo. Postal 14-740, 07360, México D.F., Mexico; Unidad de Investigación Médica en Inmunoquímica, Hospital de Especialidades del Centro Médico Nacional "Siglo XXI" IMSS, 03020 México D.F., Mexico
| | | | - Elena Arechaga-Ocampo
- Departamento de Ciencias Naturales, División de Ciencias Naturales e Ingenieria, Universidad Autónoma Metropolitana-Cuajimalpa, Av. Vasco de Quiroga 4871, Col. Santa Fe Cuajimalpa de Morelos, D.F. C.P. 05300, Mexico
| | - Raul Bonilla-Moreno
- Departamento de Biomedicina Molecular, Centro de Investigación y de Estudios Avanzados (CINVESTAV) Apdo. Postal 14-740, 07360, México D.F., Mexico
| | - Macario Martínez-Castillo
- Departamento de Biomedicina Molecular, Centro de Investigación y de Estudios Avanzados (CINVESTAV) Apdo. Postal 14-740, 07360, México D.F., Mexico
| | - Job Díaz-Hernández
- Departamento de Biomedicina Molecular, Centro de Investigación y de Estudios Avanzados (CINVESTAV) Apdo. Postal 14-740, 07360, México D.F., Mexico
| | - Oscar Del Moral-Hernández
- Laboratorio de Biomedicina Molecular, Unidad Académica de Ciencias Químico Biológicas, Universidad Autónoma de Guerrero, Avenida Lázaro Cárdenas S/N, Ciudad Universitaria, 39090 Chilpancingo, Gro, Mexico
| | - Leticia Cedillo-Barrón
- Departamento de Biomedicina Molecular, Centro de Investigación y de Estudios Avanzados (CINVESTAV) Apdo. Postal 14-740, 07360, México D.F., Mexico
| | - Víctor Martines-Juarez
- Área Académica de Medicina Veterinaria y Zootecnia, Universidad Autónoma del estado de Hidalgo, Tulancingo, Hgo, Mexico
| | - Monica De Nova-Ocampo
- Programa Institucional de Biomedicina Molecular Escuela Nacional de Medicina y Homeopatía, IPN, México D.F., Mexico
| | - Jesús Valdes
- Depto. Bioquímica, Centro de Investigación y de Estudios Avanzados-IPN (CINVESTAV-IPN), Unidad Zacatenco, 07360 México D.F., Mexico
| | - Jaime Berumen
- Facultad de Medicina, UNAM, 04510 México D.F., Mexico; Unidad de Medicina Genómica, Hospital General, México D.F., Mexico
| | - Nicolás Villegas-Sepúlveda
- Departamento de Biomedicina Molecular, Centro de Investigación y de Estudios Avanzados (CINVESTAV) Apdo. Postal 14-740, 07360, México D.F., Mexico.
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Supraspliceosomes at defined functional states portray the pre-assembled nature of the pre-mRNA processing machine in the cell nucleus. Int J Mol Sci 2014; 15:11637-64. [PMID: 24983480 PMCID: PMC4139805 DOI: 10.3390/ijms150711637] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Revised: 06/05/2014] [Accepted: 06/18/2014] [Indexed: 02/02/2023] Open
Abstract
When isolated from mammalian cell nuclei, all nuclear pre-mRNAs are packaged in multi-subunit large ribonucleoprotein complexes-supraspliceosomes-composed of four native spliceosomes interconnected by the pre-mRNA. Supraspliceosomes contain all five spliceosomal U snRNPs, together with other splicing factors, and are functional in splicing. Supraspliceosomes studied thus far represent the steady-state population of nuclear pre-mRNAs that were isolated at different stages of the splicing reaction. To analyze specific splicing complexes, here, we affinity purified Pseudomonas aeruginosa phage 7 (PP7)-tagged splicing complexes assembled in vivo on Adenovirus Major Late (AdML) transcripts at specific functional stages, and characterized them using molecular techniques including mass spectrometry. First, we show that these affinity purified splicing complexes assembled on PP7-tagged AdML mRNA or on PP7-tagged AdML pre-mRNA are assembled in supraspliceosomes. Second, similar to the general population of supraspliceosomes, these defined supraspliceosomes populations are assembled with all five U snRNPs at all splicing stages. This study shows that dynamic changes in base-pairing interactions of U snRNA:U snRNA and U snRNA:pre-mRNA that occur in vivo during the splicing reaction do not require changes in U snRNP composition of the supraspliceosome. Furthermore, there is no need to reassemble a native spliceosome for the splicing of each intron, and rearrangements of the interactions will suffice.
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Nancollis V, Ruckshanthi JPD, Frazer LN, O'Keefe RT. The U5 snRNA internal loop 1 is a platform for Brr2, Snu114 and Prp8 protein binding during U5 snRNP assembly. J Cell Biochem 2014; 114:2770-84. [PMID: 23857713 PMCID: PMC4065371 DOI: 10.1002/jcb.24625] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Accepted: 06/26/2013] [Indexed: 12/25/2022]
Abstract
The U5 small nuclear ribonucleoprotein particle (snRNP) forms the heart of the spliceosome which is required for intron removal from pre-mRNA. The proteins Prp8, Snu114 and Brr2 all assemble with the U5 small nuclear RNA (snRNA) to produce the U5 snRNP. Successful assembly of the U5 snRNP, then incorporation of this snRNP into the U4/U6.U5 tri-snRNP and the spliceosome, is essential for producing an active spliceosome. We have investigated the requirements for Prp8, Snu114 and Brr2 association with the U5 snRNA to form the U5 snRNP in yeast. Mutations were constructed in the highly conserved loop 1 and internal loop 1 (IL1) of the U5 snRNA and their function assessed in vivo. The influence of these U5 mutations on association of Prp8, Snu114 and Brr2 with the U5 snRNA were then determined. U5 snRNA loop 1 and both sides of IL1 in U5 were important for association of Prp8, Snu114 and Brr2 with the U5 snRNA. Mutations in the 3′ side of U5 IL1 resulted in the greatest reduction of Prp8, Snu114 and Brr2 association with the U5 snRNA. Genetic screening of brr2 and U5 snRNA mutants revealed synthetic lethal interactions between alleles in Brr2 and the 3′ side of U5 snRNA IL1 which reflects reduced association between Brr2 and U5 IL1. We propose that the U5 snRNA IL1 is a platform for protein binding and is required for Prp8, Brr2 and Snu114 association with the U5 snRNA to form the U5 snRNP. J. Cell. Biochem. 114: 2770–2784, 2013. © 2013 The Authors. Journal of Cellular Biochemistry Published by Wiley Periodicals Inc.
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Affiliation(s)
- Verity Nancollis
- Faculty of Life Sciences, The University of Manchester, Michael Smith Building, Oxford Road, Manchester, M13 9PT, United Kingdom
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Hadjivassiliou H, Rosenberg OS, Guthrie C. The crystal structure of S. cerevisiae Sad1, a catalytically inactive deubiquitinase that is broadly required for pre-mRNA splicing. RNA (NEW YORK, N.Y.) 2014; 20:656-69. [PMID: 24681967 PMCID: PMC3988567 DOI: 10.1261/rna.042838.113] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Accepted: 02/03/2014] [Indexed: 05/27/2023]
Abstract
Sad1 is an essential splicing factor initially identified in a genetic screen in Saccharomyces cerevisiae for snRNP assembly defects. Based on sequence homology, Sad1, or USP39 in humans, is predicted to comprise two domains: a zinc finger ubiquitin binding domain (ZnF-UBP) and an inactive ubiquitin-specific protease (iUSP) domain, both of which are well conserved. The role of these domains in splicing and their interaction with ubiquitin are unknown. We first used splicing microarrays to analyze Sad1 function in vivo and found that Sad1 is critical for the splicing of nearly all yeast intron-containing genes. By using in vitro assays, we then showed that it is required for the assembly of the active spliceosome. To gain structural insights into Sad1 function, we determined the crystal structure of the full-length protein at 1.8 Å resolution. In the structure, the iUSP domain forms the characteristic ubiquitin binding pocket, though with an amino acid substitution in the active site that results in complete inactivation of the enzymatic activity of the domain. The ZnF-UBP domain of Sad1 shares high structural similarly to other ZnF-UBPs; however, Sad1's ZnF-UBP does not possess the canonical ubiquitin binding motif. Given the precedents for ZnF-UBP domains to function as activators for their neighboring USP domains, we propose that Sad1's ZnF-UBP acts in a ubiquitin-independent capacity to recruit and/or activate Sad1's iUSP domain to interact with the spliceosome.
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Affiliation(s)
- Haralambos Hadjivassiliou
- Department of Biochemistry and Biophysics, University of California, San Francisco, California 94158, USA
| | - Oren S. Rosenberg
- Division of Infectious Diseases, Department of Medicine, University of California, San Francisco, California 94143-0414, USA
| | - Christine Guthrie
- Department of Biochemistry and Biophysics, University of California, San Francisco, California 94158, USA
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Abstract
One of the most amazing findings in molecular biology was the discovery that eukaryotic genes are discontinuous, with coding DNA being interrupted by stretches of non-coding sequence. The subsequent realization that the intervening regions are removed from pre-mRNA transcripts via the activity of a common set of small nuclear RNAs (snRNAs), which assemble together with associated proteins into a complex known as the spliceosome, was equally surprising. How do cells coordinate the assembly of this molecular machine? And how does the spliceosome accurately recognize exons and introns to carry out the splicing reaction? Insights into these questions have been gained by studying the life cycle of spliceosomal snRNAs from their transcription, nuclear export and re-import to their dynamic assembly into the spliceosome. This assembly process can also affect the regulation of alternative splicing and has implications for human disease.
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Affiliation(s)
- A Gregory Matera
- Department of Biology, Department of Genetics and Integrative Program for Biological and Genome Sciences, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - Zefeng Wang
- Department of Pharmacology, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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Wlodaver AM, Staley JP. The DExD/H-box ATPase Prp2p destabilizes and proofreads the catalytic RNA core of the spliceosome. RNA (NEW YORK, N.Y.) 2014; 20:282-94. [PMID: 24442613 PMCID: PMC3923124 DOI: 10.1261/rna.042598.113] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Accepted: 10/30/2013] [Indexed: 05/25/2023]
Abstract
After undergoing massive RNA and protein rearrangements during assembly, the spliceosome undergoes a final, more subtle, ATP-dependent rearrangement that is essential for catalysis. This rearrangement requires the DEAH-box protein Prp2p, an RNA-dependent ATPase. Prp2p has been implicated in destabilizing interactions between the spliceosome and the protein complexes SF3 and RES, but a role for Prp2p in destabilizing RNA-RNA interactions has not been explored. Using directed molecular genetics in budding yeast, we have found that a cold-sensitive prp2 mutation is suppressed not only by mutations in SF3 and RES components but also by a range of mutations that disrupt the spliceosomal catalytic core element U2/U6 helix I, which is implicated in juxtaposing the 5' splice site and branch site and in positioning metal ions for catalysis within the context of a putative catalytic triplex; indeed, mutations in this putative catalytic triplex also suppressed a prp2 mutation. Remarkably, we also found that prp2 mutations rescue lethal mutations in U2/U6 helix I. These data provide evidence that RNA elements that comprise the catalytic core are already formed at the Prp2p stage and that Prp2p destabilizes these elements, directly or indirectly, both to proofread spliceosome activation and to promote reconfiguration of the spliceosome to a fully competent, catalytic conformation.
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Lsm2 and Lsm3 bridge the interaction of the Lsm1-7 complex with Pat1 for decapping activation. Cell Res 2013; 24:233-46. [PMID: 24247251 PMCID: PMC3915908 DOI: 10.1038/cr.2013.152] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 09/16/2013] [Accepted: 09/28/2013] [Indexed: 02/07/2023] Open
Abstract
The evolutionarily conserved Lsm1-7-Pat1 complex is the most critical activator of mRNA decapping in eukaryotic cells and plays many roles in normal decay, AU-rich element-mediated decay, and miRNA silencing, yet how Pat1 interacts with the Lsm1-7 complex is unknown. Here, we show that Lsm2 and Lsm3 bridge the interaction between the C-terminus of Pat1 (Pat1C) and the Lsm1-7 complex. The Lsm2-3-Pat1C complex and the Lsm1-7-Pat1C complex stimulate decapping in vitro to a similar extent and exhibit similar RNA-binding preference. The crystal structure of the Lsm2-3-Pat1C complex shows that Pat1C binds to Lsm2-3 to form an asymmetric complex with three Pat1C molecules surrounding a heptameric ring formed by Lsm2-3. Structure-based mutagenesis revealed the importance of Lsm2-3-Pat1C interactions in decapping activation in vivo. Based on the structure of Lsm2-3-Pat1C, a model of Lsm1-7-Pat1 complex is constructed and how RNA binds to this complex is discussed.
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34
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Splicing functions and global dependency on fission yeast slu7 reveal diversity in spliceosome assembly. Mol Cell Biol 2013; 33:3125-36. [PMID: 23754748 DOI: 10.1128/mcb.00007-13] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The multiple short introns in Schizosaccharomyces pombe genes with degenerate cis sequences and atypically positioned polypyrimidine tracts make an interesting model to investigate canonical and alternative roles for conserved splicing factors. Here we report functions and interactions of the S. pombe slu7(+) (spslu7(+)) gene product, known from Saccharomyces cerevisiae and human in vitro reactions to assemble into spliceosomes after the first catalytic reaction and to dictate 3' splice site choice during the second reaction. By using a missense mutant of this essential S. pombe factor, we detected a range of global splicing derangements that were validated in assays for the splicing status of diverse candidate introns. We ascribe widespread, intron-specific SpSlu7 functions and have deduced several features, including the branch nucleotide-to-3' splice site distance, intron length, and the impact of its A/U content at the 5' end on the intron's dependence on SpSlu7. The data imply dynamic substrate-splicing factor relationships in multiintron transcripts. Interestingly, the unexpected early splicing arrest in spslu7-2 revealed a role before catalysis. We detected a salt-stable association with U5 snRNP and observed genetic interactions with spprp1(+), a homolog of human U5-102k factor. These observations together point to an altered recruitment and dependence on SpSlu7, suggesting its role in facilitating transitions that promote catalysis, and highlight the diversity in spliceosome assembly.
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Dreumont N, Séraphin B. Rapid screening of yeast mutants with reporters identifies new splicing phenotypes. FEBS J 2013; 280:2712-26. [PMID: 23560879 DOI: 10.1111/febs.12277] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Revised: 04/01/2013] [Accepted: 04/02/2013] [Indexed: 11/29/2022]
Abstract
Nuclear precursor mRNA splicing requires the stepwise assembly of a large complex, the spliceosome. Recent large-scale analyses, including purification of splicing complexes, high-throughput genetic screens and interactomic studies, have linked numerous factors to this dynamic process, including a well-defined core conserved from yeast to human. Intriguingly, despite extensive studies, no splicing defects were reported for some of the corresponding yeast mutants. To resolve this paradox, we screened a collection of viable yeast strains carrying mutations in splicing-related factors with a set of reporters including artificial constructs carrying competing splice sites. Previous analyses have indeed demonstrated that this strategy identifies yeast factors able to regulate alternative splicing and whose properties are conserved in human cells. The method, sensitive to subtle defects, revealed new splicing phenotypes for most analyzed factors such as the Urn1 protein. Interestingly, a mutant of PRP8 specifically lacking an N-terminal proline-rich region stimulated the splicing of a reporter containing competing branchpoint/3' splice site regions. Thus, using appropriate reporters, yeast can be used to quickly delineate the effect of various factors on splicing and identify those with the propensity to regulate alternative splicing events.
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Affiliation(s)
- Natacha Dreumont
- Equipe Labellisée La Ligue, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Université de Strasbourg, 67404 Illkirch, France
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Chang TH, Tung L, Yeh FL, Chen JH, Chang SL. Functions of the DExD/H-box proteins in nuclear pre-mRNA splicing. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2013; 1829:764-74. [PMID: 23454554 DOI: 10.1016/j.bbagrm.2013.02.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Revised: 02/05/2013] [Accepted: 02/13/2013] [Indexed: 01/09/2023]
Abstract
In eukaryotes, many genes are transcribed as precursor messenger RNAs (pre-mRNAs) that contain exons and introns, the latter of which must be removed and exons ligated to form the mature mRNAs. This process is called pre-mRNA splicing, which occurs in the nucleus. Although the chemistry of pre-mRNA splicing is identical to that of the self-splicing Group II introns, hundreds of proteins and five small nuclear RNAs (snRNAs), U1, U2, U4, U5, and U6, are essential for executing pre-mRNA splicing. Spliceosome, arguably the most complex cellular machine made up of all those proteins and snRNAs, is responsible for carrying out pre-mRNA splicing. In contrast to the transcription and the translation machineries, spliceosome is formed anew onto each pre-mRNA and undergoes a series of highly coordinated reconfigurations to form the catalytic center. This amazing process is orchestrated by a number of DExD/H-proteins that are the focus of this article, which aims to review the field in general and to project the exciting challenges and opportunities ahead. This article is part of a Special Issue entitled: The Biology of RNA helicases - Modulation for life.
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37
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Patterson J, Mura C. Rapid colorimetric assays to qualitatively distinguish RNA and DNA in biomolecular samples. J Vis Exp 2013:e50225. [PMID: 23407542 DOI: 10.3791/50225] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Biochemical experimentation generally requires accurate knowledge, at an early stage, of the nucleic acid, protein, and other biomolecular components in potentially heterogeneous specimens. Nucleic acids can be detected via several established approaches, including analytical methods that are spectrophotometric (e.g., A(260)), fluorometric (e.g., binding of fluorescent dyes), or colorimetric (nucleoside-specific chromogenic chemical reactions).(1) Though it cannot readily distinguish RNA from DNA, the A(260)/A(280) ratio is commonly employed, as it offers a simple and rapid(2) assessment of the relative content of nucleic acid, which absorbs predominantly near 260 nm and protein, which absorbs primarily near 280 nm. Ratios < 0.8 are taken as indicative of 'pure' protein specimens, while pure nucleic acid (NA) is characterized by ratios > 1.5(3). However, there are scenarios in which the protein/NA content cannot be as clearly or reliably inferred from simple uv-vis spectrophotometric measurements. For instance, (i) samples may contain one or more proteins which are relatively devoid of the aromatic amino acids responsible for absorption at ≈280 nm (Trp, Tyr, Phe), as is the case with some small RNA-binding proteins, and (ii) samples can exhibit intermediate A(260)/A(280) ratios (~0.8 < ~1.5), where the protein/NA content is far less clear and may even reflect some high-affinity association between the protein and NA components. For such scenarios, we describe herein a suite of colorimetric assays to rapidly distinguish RNA, DNA, and reducing sugars in a potentially mixed sample of biomolecules. The methods rely on the differential sensitivity of pentoses and other carbohydrates to Benedict's, Bial's (orcinol), and Dische's (diphenylamine) reagents; the streamlined protocols can be completed in a matter of minutes, without any additional steps of having to isolate the components. The assays can be performed in parallel to differentiate between RNA and DNA, as well as indicate the presence of free reducing sugars such as glucose, fructose, and ribose (Figure 1).
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Abstract
Members of the DEAD box family of RNA helicases are known to be involved in most cellular processes that require manipulation of RNA structure and, in many cases, exhibit other functions in addition to their established ATP-dependent RNA helicase activities. They thus play critical roles in cellular metabolism and in many cases have been implicated in cellular proliferation and/or neoplastic transformation. These proteins generally act as components of multi-protein complexes; therefore their precise role is likely to be influenced by their interacting partners and to be highly context-dependent. This may also provide an explanation for the sometimes conflicting reports suggesting that DEAD box proteins have both pro- and anti-proliferative roles in cancer.
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Affiliation(s)
- Frances V Fuller-Pace
- Division of Cancer Research, University of Dundee, Ninewells Hospital and Medical School, Dundee, Scotland.
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Chin CH, Chen SH, Chen CY, Hsiung CA, Ho CW, Ko MT, Lin CY. Spotlight: assembly of protein complexes by integrating graph clustering methods. Gene 2012; 518:42-51. [PMID: 23274651 DOI: 10.1016/j.gene.2012.11.087] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Accepted: 11/27/2012] [Indexed: 02/01/2023]
Abstract
UNLABELLED As is generally assumed, clusters in protein-protein interaction (PPI) networks perform specific, crucial functions in biological systems. Various network community detection methods have been developed to exploit PPI networks in order to identify protein complexes and functional modules. Due to the potential role of various regulatory modes in biological networks, a single method may just apply a single graph property and neglect communities highlighted by other network properties. This work presents a novel integration method to capture protein modules/protein complexes by multiple network features detected by different algorithms. The integration method is further implemented in a web-based platform with a highly effective interactive network analyzer. Conventionally adopted methods with different perspectives on network community detection (e.g., CPM, FastGreedy, HUNTER, MCL, LE, SpinGlass, and WalkTrap) are also executed simultaneously. Analytical results indicate that the proposed method performs better than the conventional ones. The proposed approach can capture the transcription and RNA splicing machineries from the yeast protein network. Meanwhile, proteins that are highly associated with each other, yet not described in both machineries are also identified. In sum, a protein that is closely connected to components of a known module or a complex in the network view implies the functional association among them. Importantly, our method can detect these unique network features, thus facilitating efforts to discover unknown components of functional modules/protein complexes. AVAILABILITY Spotlight is freely accessible at http://hub.iis.sinica.edu.tw/spotlight. Video clips for a quick view of usage are available in the website online help page.
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Affiliation(s)
- Chia-Hao Chin
- Institute of Information Science, Academia Sinica, No. 128 Yan-Chiu-Yuan Rd., Sec. 2, Taipei 115, Taiwan
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Abstract
RNA splicing is one of the fundamental processes in gene expression in eukaryotes. Splicing of pre-mRNA is catalysed by a large ribonucleoprotein complex called the spliceosome, which consists of five small nuclear RNAs and numerous protein factors. The spliceosome is a highly dynamic structure, assembled by sequential binding and release of the small nuclear RNAs and protein factors. DExD/H-box RNA helicases are required to mediate structural changes in the spliceosome at various steps in the assembly pathway and have also been implicated in the fidelity control of the splicing reaction. Other proteins also play key roles in mediating the progression of the spliceosome pathway. In this review, we discuss the functional roles of the protein factors involved in the spliceosome pathway primarily from studies in the yeast system.
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Cvitkovic I, Jurica MS. Spliceosome database: a tool for tracking components of the spliceosome. Nucleic Acids Res 2012; 41:D132-41. [PMID: 23118483 PMCID: PMC3531166 DOI: 10.1093/nar/gks999] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The spliceosome is the extremely complex macromolecular machine responsible for pre-mRNA splicing. It assembles from five U-rich small nuclear RNAs (snRNAs) and over 200 proteins in a highly dynamic fashion. One important challenge to studying the spliceosome is simply keeping track of all these proteins, a situation further complicated by the variety of names and identifiers that exist in the literature for them. To facilitate studies of the spliceosome and its components, we created a database of spliceosome-associated proteins and snRNAs, which is available at http://spliceosomedb.ucsc.edu and can be queried through a simple browser interface. In the database, we cataloged the various names, orthologs and gene identifiers of spliceosome proteins to navigate the complex nomenclature of spliceosome proteins. We also provide links to gene and protein records for the spliceosome components in other databases. To navigate spliceosome assembly dynamics, we created tools to compare the association of spliceosome proteins with complexes that form at specific stages of spliceosome assembly based on a compendium of mass spectrometry experiments that identified proteins in purified splicing complexes. Together, the information in the database provides an easy reference for spliceosome components and will support future modeling of spliceosome structure and dynamics.
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Affiliation(s)
- Ivan Cvitkovic
- Department of Molecular, Cell and Developmental Biology and Center for Molecular Biology of RNA, University of California, 1156 High Street, Santa Cruz, CA 95064, USA
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Coltri PP, Oliveira CC. Cwc24p is a general Saccharomyces cerevisiae splicing factor required for the stable U2 snRNP binding to primary transcripts. PLoS One 2012; 7:e45678. [PMID: 23029180 PMCID: PMC3454408 DOI: 10.1371/journal.pone.0045678] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Accepted: 08/23/2012] [Indexed: 12/31/2022] Open
Abstract
Splicing of primary transcripts is an essential process for the control of gene expression. Specific conserved sequences in premature transcripts are important to recruit the spliceosome machinery. The Saccharomyces cerevisiae catalytic spliceosome is composed of about 60 proteins and 5 snRNAs (U1, U2, U4/U6 and U5). Among these proteins, there are core components and regulatory factors, which might stabilize or facilitate splicing of specific substrates. Assembly of a catalytic complex depends on the dynamics of interactions between these proteins and RNAs. Cwc24p is an essential S. cerevisiae protein, originally identified as a component of the NTC complex, and later shown to affect splicing in vivo. In this work, we show that Cwc24p also affects splicing in vitro. We show that Cwc24p is important for the U2 snRNP binding to primary transcripts, co-migrates with spliceosomes, and that it interacts with Brr2p. Additionally, we show that Cwc24p is important for the stable binding of Prp19p to the spliceosome. We propose a model in which Cwc24p is required for stabilizing the U2 association with primary transcripts, and therefore, especially important for splicing of RNAs containing non-consensus branchpoint sequences.
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Affiliation(s)
- Patricia P. Coltri
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, SP, Brazil
| | - Carla C. Oliveira
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, SP, Brazil
- * E-mail:
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43
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Aulds J, Wierzbicki S, McNairn A, Schmitt ME. Global identification of new substrates for the yeast endoribonuclease, RNase mitochondrial RNA processing (MRP). J Biol Chem 2012; 287:37089-97. [PMID: 22977255 DOI: 10.1074/jbc.m112.389023] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
RNase mitochondrial RNA processing (MRP) is an essential, evolutionarily conserved endoribonuclease composed of 10 different protein subunits and a single RNA. RNase MRP has established roles in multiple pathways including ribosome biogenesis, cell cycle regulation, and mitochondrial DNA replication. Although each of these functions is important to cell growth, additional functions may exist given the essential nature of the complex. To identify novel RNase MRP substrates, we utilized RNA immunoprecipitation and microarray chip analysis to identify RNA that physically associates with RNase MRP. We identified several new potential substrates for RNase MRP including a cell cycle-regulated transcript, CTS1; the yeast homolog of the mammalian p27(Kip1), SIC1; and the U2 RNA component of the spliceosome. In addition, we found RNase MRP to be involved in the regulation of the Ty1 transposon RNA. These results reinforce and broaden the role of RNase MRP in cell cycle regulation and help to identify new roles of this endoribonuclease.
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Affiliation(s)
- Jason Aulds
- Department of Biochemistry and Molecular Biology, State University of New York Upstate Medical University, Syracuse, New York 13210, USA
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Abstract
Persistent infection with cancer risk-related viruses leads to molecular, cellular and immune response changes in host organisms that in some cases direct cellular transformation. Alternative splicing is a conserved cellular process that increases the coding complexity of genomes at the pre-mRNA processing stage. Human and other animal tumour viruses use alternative splicing as a process to maximize their transcriptomes and proteomes. Medical therapeutics to clear persistent viral infections are still limited. However, specific lessons learned in some viruses [e.g. HIV and HCV (hepatitis C virus)] suggest that drug-directed inhibition of alternative splicing could be useful for this purpose. The present review describes the basic mechanisms of constitutive and alternative splicing in a cellular context and known splicing patterns and the mechanisms by which these might be achieved for the major human infective tumour viruses. The roles of splicing-related proteins expressed by these viruses in cellular and viral gene regulation are explored. Moreover, we discuss some currently available drugs targeting SR (serine/arginine-rich) proteins that are the main regulators of constitutive and alternative splicing, and their potential use in treatment for so-called persistent viral infections.
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45
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Schmidt C, Kramer K, Urlaub H. Investigation of protein-RNA interactions by mass spectrometry--Techniques and applications. J Proteomics 2012; 75:3478-94. [PMID: 22575267 DOI: 10.1016/j.jprot.2012.04.030] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Revised: 04/19/2012] [Accepted: 04/22/2012] [Indexed: 12/26/2022]
Abstract
Protein-RNA complexes play many important roles in diverse cellular functions. They are involved in a wide variety of different processes in growth and differentiation at the various stages of the cell cycle. As their function and catalytic activity are directly coupled to the structural arrangement of their components--proteins and ribonucleic acids--the investigation of protein-RNA interactions is of great functional and structural importance. Here we discuss the most prominent examples of protein-RNA complexes and describe some frequently used purification strategies. We present various techniques and applications of mass spectrometry to study protein-RNA complexes. We discuss the analysis of intact complexes as well as proteomics-based and crosslinking-based approaches in which proteins are cleaved into smaller peptides. This article is part of a Special Section entitled: Understanding genome regulation and genetic diversity by mass spectrometry.
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Affiliation(s)
- Carla Schmidt
- Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
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James K, Wipat A, Hallinan J. Is newer better?--evaluating the effects of data curation on integrated analyses in Saccharomyces cerevisiae. Integr Biol (Camb) 2012; 4:715-27. [PMID: 22526920 DOI: 10.1039/c2ib00123c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Recent high-throughput experiments have produced a wealth of heterogeneous datasets, each of which provides information about different aspects of the cell. Consequently, integration of diverse data types is essential in order to address many biological questions. The quality of any integrated analysis system is dependent upon the quality of its component data, and upon the Gold Standard data used to evaluate it. It is commonly assumed that the quality of data improves as databases grow and change, particularly for manually curated databases. However, the validity of this assumption can be questioned, given the constant changes in the data coupled with the high level of noise associated with high-throughput experimental techniques. One of the most powerful approaches to data integration is the use of Probabilistic Functional Integrated Networks (PFINs). Here, we systematically analyse the changes in four highly-curated and widely-used online databases and evaluate the extent to which these changes affect the protein function prediction performance of PFINs in the yeast Saccharomyces cerevisiae. We find that the global trend in network performance improves over time. Where individual areas of biology are concerned, however, the most recent files do not always produce the best results. Individual datasets have unique biases towards different biological processes and by selecting and integrating relevant datasets performance can be improved. When using any type of integrated system to answer a specific biological question careful selection of raw data and Gold Standard is vital, since the most recent data may not be the most appropriate.
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Affiliation(s)
- Katherine James
- School of Computing Science, Newcastle University, Newcastle upon Tyne, NE1 7RU, United Kingdom
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Koncz C, deJong F, Villacorta N, Szakonyi D, Koncz Z. The spliceosome-activating complex: molecular mechanisms underlying the function of a pleiotropic regulator. FRONTIERS IN PLANT SCIENCE 2012; 3:9. [PMID: 22639636 PMCID: PMC3355604 DOI: 10.3389/fpls.2012.00009] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Accepted: 01/09/2012] [Indexed: 05/18/2023]
Abstract
Correct interpretation of the coding capacity of RNA polymerase II transcribed eukaryotic genes is determined by the recognition and removal of intronic sequences of pre-mRNAs by the spliceosome. Our current knowledge on dynamic assembly and subunit interactions of the spliceosome mostly derived from the characterization of yeast, Drosophila, and human spliceosomal complexes formed on model pre-mRNA templates in cell extracts. In addition to sequential structural rearrangements catalyzed by ATP-dependent DExH/D-box RNA helicases, catalytic activation of the spliceosome is critically dependent on its association with the NineTeen Complex (NTC) named after its core E3 ubiquitin ligase subunit PRP19. NTC, isolated recently from Arabidopsis, occurs in a complex with the essential RNA helicase and GTPase subunits of the U5 small nuclear RNA particle that are required for both transesterification reactions of splicing. A compilation of mass spectrometry data available on the composition of NTC and spliceosome complexes purified from different organisms indicates that about half of their conserved homologs are encoded by duplicated genes in Arabidopsis. Thus, while mutations of single genes encoding essential spliceosome and NTC components lead to cell death in other organisms, differential regulation of some of their functionally redundant Arabidopsis homologs permits the isolation of partial loss of function mutations. Non-lethal pleiotropic defects of these mutations provide a unique means for studying the roles of NTC in co-transcriptional assembly of the spliceosome and its crosstalk with DNA repair and cell death signaling pathways.
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Affiliation(s)
- Csaba Koncz
- Department of Plant Developmental Biology, Max-Planck Institute for Plant Breeding ResearchCologne, Germany
- Institute of Plant Biology, Biological Research Center of Hungarian Academy of SciencesSzeged, Hungary
- *Correspondence: Csaba Koncz, Department of Plant Developmental Biology, Max-Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, D-59829 Cologne, Germany. e-mail:
| | - Femke deJong
- Department of Plant Developmental Biology, Max-Planck Institute for Plant Breeding ResearchCologne, Germany
| | - Nicolas Villacorta
- Department of Plant Developmental Biology, Max-Planck Institute for Plant Breeding ResearchCologne, Germany
| | - Dóra Szakonyi
- Department of Plant Developmental Biology, Max-Planck Institute for Plant Breeding ResearchCologne, Germany
| | - Zsuzsa Koncz
- Department of Plant Developmental Biology, Max-Planck Institute for Plant Breeding ResearchCologne, Germany
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Hoskins AA, Gelles J, Moore MJ. New insights into the spliceosome by single molecule fluorescence microscopy. Curr Opin Chem Biol 2011; 15:864-70. [PMID: 22057211 DOI: 10.1016/j.cbpa.2011.10.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Revised: 10/10/2011] [Accepted: 10/17/2011] [Indexed: 11/17/2022]
Abstract
Splicing is an essential eukaryotic process in which introns are excised from precursors to messenger RNAs and exons ligated together. This reaction is catalyzed by a multi-MegaDalton machine called the spliceosome, composed of 5 small nuclear RNAs (snRNAs) and a core set of ∼100 proteins minimally required for activity. Because of the spliceosome's size, its low abundance in cellular extracts, and its highly dynamic assembly pathway, analysis of the kinetics of splicing and the conformational rearrangements occurring during spliceosome assembly and disassembly has proven extraordinarily challenging. Here, we review recent progress in combining chemical biology methodologies with single molecule fluorescence techniques to provide a window into splicing in real time. These methods complement ensemble measurements of splicing in vivo and in vitro to facilitate kinetic dissection of pre-mRNA splicing.
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MESH Headings
- Biotin/chemistry
- Biotin/metabolism
- Exons
- Fluorescence Resonance Energy Transfer
- Fluorescent Dyes/analysis
- Fluorescent Dyes/chemistry
- Introns
- Microscopy, Fluorescence/methods
- RNA Precursors/analysis
- RNA Precursors/chemistry
- RNA Precursors/metabolism
- RNA Splicing/genetics
- RNA, Fungal/analysis
- RNA, Fungal/chemistry
- RNA, Fungal/metabolism
- RNA, Small Nuclear/analysis
- RNA, Small Nuclear/chemistry
- RNA, Small Nuclear/metabolism
- Ribonucleoproteins, Small Nuclear/analysis
- Ribonucleoproteins, Small Nuclear/chemistry
- Ribonucleoproteins, Small Nuclear/metabolism
- Saccharomyces cerevisiae/genetics
- Saccharomyces cerevisiae/metabolism
- Spliceosomes/chemistry
- Spliceosomes/genetics
- Spliceosomes/metabolism
- Staining and Labeling/methods
- Streptavidin/chemistry
- Streptavidin/metabolism
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Affiliation(s)
- Aaron A Hoskins
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 364 Plantation St., Worcester, MA 01605, USA.
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Tuteja R. Helicases involved in splicing from malaria parasite Plasmodium falciparum. Parasitol Int 2011; 60:335-40. [PMID: 21996352 DOI: 10.1016/j.parint.2011.09.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2011] [Revised: 09/14/2011] [Accepted: 09/18/2011] [Indexed: 02/06/2023]
Abstract
An interesting element of eukaryotic genomes is the large quantity of non-coding intervening sequences commonly known as introns, which regularly interrupt functional genes and therefore must be removed prior to the use of genetic information by the cell. After splicing, the mature RNA is exported from the nucleus to the cytoplasm. Any error in the process of recognition and removal of introns, or splicing, would lead to change in genetic message and thus has potentially catastrophic consequences. Thus splicing is a highly complex essential step in eukaryotic gene expression. It takes place in spliceosome, which is a dynamic RNA-protein complex made of snRNPs and non-snRNP proteins. The splicing process consists of following sequential steps: spliceosome formation, the first transesterification and second transesterification reactions, release of the mature mRNA and recycling of the snRNPs. The spliceosomal components produce a complex network of RNA-RNA, RNA-protein and protein-protein interactions and spliceosome experience remodeling during each splicing cycle. Helicases are essentially required at almost each step for resolution of RNA-RNA and/or RNA-protein interactions. RNA helicases share a highly conserved helicase domain which includes the motif DExD/H in the single letter amino acid code. This article will focus on members of the DExD/H-box proteins involved specially in splicing in the malaria parasite Plasmodium falciparum.
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Affiliation(s)
- Renu Tuteja
- International Centre for Genetic Engineering and Biotechnology, New Delhi, India.
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50
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Hedstrom L, Liechti G, Goldberg JB, Gollapalli DR. The antibiotic potential of prokaryotic IMP dehydrogenase inhibitors. Curr Med Chem 2011; 18:1909-18. [PMID: 21517780 DOI: 10.2174/092986711795590129] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Accepted: 04/04/2011] [Indexed: 12/30/2022]
Abstract
Inosine 5'-monophosphate dehydrogenase (IMPDH) catalyzes the first committed step of guanosine 5'-monophosphate (GMP) biosynthesis, and thus regulates the guanine nucleotide pool, which in turn governs proliferation. Human IMPDHs are validated targets for immunosuppressive, antiviral and anticancer drugs, but as yet microbial IMPDHs have not been exploited in antimicrobial chemotherapy. Selective inhibitors of IMPDH from Cryptosporidium parvum have recently been discovered that display anti-parasitic activity in cell culture models of infection. X-ray crystal structure and mutagenesis experiments identified the structural features that determine inhibitor susceptibility. These features are found in IMPDHs from a wide variety of pathogenic bacteria, including select agents and multiply drug resistant strains. A second generation inhibitor displays antibacterial activity against Helicobacter pylori, demonstrating the antibiotic potential of IMPDH inhibitors.
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Affiliation(s)
- L Hedstrom
- Brandeis University, Departments of Biology, Waltham, MA 02454-9110, USA.
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