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Yang H, Xun Y, Ke C, Tateishi K, You H. Extranodal lymphoma: pathogenesis, diagnosis and treatment. MOLECULAR BIOMEDICINE 2023; 4:29. [PMID: 37718386 PMCID: PMC10505605 DOI: 10.1186/s43556-023-00141-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2023] [Accepted: 08/18/2023] [Indexed: 09/19/2023] Open
Abstract
Approximately 30% of lymphomas occur outside the lymph nodes, spleen, or bone marrow, and the incidence of extranodal lymphoma has been rising in the past decade. While traditional chemotherapy and radiation therapy can improve survival outcomes for certain patients, the prognosis for extranodal lymphoma patients remains unsatisfactory. Extranodal lymphomas in different anatomical sites often have distinct cellular origins, pathogenic mechanisms, and clinical manifestations, significantly influencing their diagnosis and treatment. Therefore, it is necessary to provide a comprehensive summary of the pathogenesis, diagnosis, and treatment progress of extranodal lymphoma overall and specifically for different anatomical sites. This review summarizes the current progress in the common key signaling pathways in the development of extranodal lymphomas and intervention therapy. Furthermore, it provides insights into the pathogenesis, diagnosis, and treatment strategies of common extranodal lymphomas, including gastric mucosa-associated lymphoid tissue (MALT) lymphoma, mycosis fungoides (MF), natural killer/T-cell lymphoma (nasal type, NKTCL-NT), and primary central nervous system lymphoma (PCNSL). Additionally, as PCNSL is one of the extranodal lymphomas with the worst prognosis, this review specifically summarizes prognostic indicators and discusses the challenges and opportunities related to its clinical applications. The aim of this review is to assist clinical physicians and researchers in understanding the current status of extranodal lymphomas, enabling them to make informed clinical decisions that contribute to improving patient prognosis.
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Affiliation(s)
- Hua Yang
- Department of Basic Medicine and Biomedical Engineering, School of Medicine, Foshan University, Foshan, 528000, China
| | - Yang Xun
- Department of Basic Medicine and Biomedical Engineering, School of Medicine, Foshan University, Foshan, 528000, China
| | - Chao Ke
- Department of Neurosurgery and Neuro-Oncology, Sun Yat-Sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, 510060, China
| | - Kensuke Tateishi
- Department of Neurosurgery, Graduate School of Medicine, Yokohama City University, Yokohama, 2360004, Japan
| | - Hua You
- Laboratory for Excellence in Systems Biomedicine of Pediatric Oncology, Department of Pediatric Hematology and Oncology, Chongqing Key Laboratory of Pediatrics, Ministry of Education Key Laboratory of Child Development and Disorders, China International Science and Technology Cooperation base of Child development and Critical Disorders, National Clinical Research Center for Child Health and Disorders, Children's Hospital of Chongqing Medical University, Chongqing, 401122, China.
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2
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Effect of biological matrix and sample preparation on qPCR quantitation of siRNA drugs in animal tissues. J Pharmacol Toxicol Methods 2011; 63:168-73. [DOI: 10.1016/j.vascn.2010.09.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2010] [Accepted: 09/17/2010] [Indexed: 10/19/2022]
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3
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Melcák I, Melcáková S, Kopský V, Vecerová J, Raska I. Prespliceosomal assembly on microinjected precursor mRNA takes place in nuclear speckles. Mol Biol Cell 2001; 12:393-406. [PMID: 11179423 PMCID: PMC30951 DOI: 10.1091/mbc.12.2.393] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2000] [Revised: 11/03/2000] [Accepted: 12/19/2000] [Indexed: 11/11/2022] Open
Abstract
Nuclear speckles (speckles) represent a distinct nuclear compartment within the interchromatin space and are enriched in splicing factors. They have been shown to serve neighboring active genes as a reservoir of these factors. In this study, we show that, in HeLa cells, the (pre)spliceosomal assembly on precursor mRNA (pre-mRNA) is associated with the speckles. For this purpose, we used microinjection of splicing competent and mutant adenovirus pre-mRNAs with differential splicing factor binding, which form different (pre)spliceosomal complexes and followed their sites of accumulation. Splicing competent pre-mRNAs are rapidly targeted into the speckles, but the targeting is temperature-dependent. The polypyrimidine tract sequence is required for targeting, but, in itself, is not sufficient. The downstream flanking sequences are particularly important for the targeting of the mutant pre-mRNAs into the speckles. In supportive experiments, the behavior of the speckles was followed after the microinjection of antisense deoxyoligoribonucleotides complementary to the specific domains of snRNAs. Under these latter conditions prespliceosomal complexes are formed on endogenous pre-mRNAs. We conclude that the (pre)spliceosomal complexes on microinjected pre-mRNA are formed inside the speckles. Their targeting into and accumulation in the speckles is a result of the cumulative loading of splicing factors to the pre-mRNA and the complexes formed give rise to the speckled pattern observed.
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Affiliation(s)
- I Melcák
- Department of Cell Biology, Institute of Experimental Medicine, Academy of Sciences of Czech Republic, Prague
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4
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Luukkonen BG, Séraphin B. A conditional U5 snRNA mutation affecting pre-mRNA splicing and nuclear pre-mRNA retention identifies SSD1/SRK1 as a general splicing mutant suppressor. Nucleic Acids Res 1999; 27:3455-65. [PMID: 10446233 PMCID: PMC148587 DOI: 10.1093/nar/27.17.3455] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
A combination of point mutations disrupting both stem 1 and stem 2 of U5 snRNA (U5AI) was found to confer a thermosensitive phenotype in vivo. In a strain expressing U5AI, pre-mRNA splicing was blocked before the first step through an inability of the mutant U5 snRNA to efficiently associate with the U4/U6 di-snRNP. Formation of early splicing complexes was not affected in extracts prepared from U5 snRNA mutant cells, while the capacity of these extracts to splice a pre-mRNA in vitro was greatly diminished. In addition, significant levels of a translation product derived from intron containing pre-mRNAs could be detected in vivo. The SSD1/SRK1 gene was identified as a multi-copy suppressor of the U5AI snRNA mutant. Single copy expression of SSD1/SRK1 was sufficient to suppress the thermosensitive phenotype, and high copy expression partially suppressed the splicing and U4/U6.U5 tri-snRNP assembly pheno-types. SSD1/SRK1 also suppressed thermosensitive mutations in the Prp18p and U1-70K proteins, while inhibiting growth of the cold sensitive U1-4U snRNA mutant at 30 degrees C. Thus we have identified SSD1/SRK1 as a general suppressor of splicing mutants.
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Affiliation(s)
- B G Luukkonen
- European Molecular Biology Laboratory, Meyerhofstrasse 1, D-69117 Heidelberg, Germany
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5
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Olivas WM, Muhlrad D, Parker R. Analysis of the yeast genome: identification of new non-coding and small ORF-containing RNAs. Nucleic Acids Res 1997; 25:4619-25. [PMID: 9358174 PMCID: PMC147069 DOI: 10.1093/nar/25.22.4619] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The genome sequences from increasing numbers of organisms allow for rapid and organized examination of gene expression. Yet current computational-based paradigms for gene recognition are limited and likely to miss genes expressing non-coding RNAs or mRNAs with small open reading frames (ORFs). We have utilized two strategies to determine if there are additional transcripts in the yeast Saccharomyces cerevisiae that were not identified in previous analyses of the genome. In one approach, we identified strong consensus polymerase III promoters based on sequence, and determined experimentally if these promoters drive the expression of an RNA polymerase III transcript. This approach led to the identification of a new, non-essential 170 nt non-coding RNA. An alternative strategy analyzed RNA expression from large sequence gaps>2 kb between predicted ORFs. Fifteen unique RNA transcripts ranging in size from 161 to 1200 nt were identified from a total of 59 sequence gaps. Several of these RNAs contain unusually small potential ORFs, while one is clearly non-coding and appears to be a small nucleolar RNA. These results suggest that there are likely to be additional previously unidentified non-coding RNAs in yeast, and that new paradigms for gene recognition will be required to identify all expressed genes from an organism.
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Affiliation(s)
- W M Olivas
- Department of Molecular and Cellular Biology and Howard Hughes Medical Institute, University of Arizona, Tucson, AZ 85721, USA
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6
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Weidenhammer EM, Ruiz-Noriega M, Woolford JL. Prp31p promotes the association of the U4/U6 x U5 tri-snRNP with prespliceosomes to form spliceosomes in Saccharomyces cerevisiae. Mol Cell Biol 1997; 17:3580-8. [PMID: 9199293 PMCID: PMC232211 DOI: 10.1128/mcb.17.7.3580] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The PRP31 gene encodes a factor essential for the splicing of pre-mRNA in Saccharomyces cerevisiae. Cell extracts derived from a prp31-1 strain fail to form mature spliceosomes upon heat inactivation, although commitment complexes and prespliceosome complexes are detected under these conditions. Coimmunoprecipitation experiments indicate that Prp31p is associated both with the U4/U6 x U5 tri-snRNP and, independently, with the prespliceosome prior to assembly of the tri-snRNP into the splicing complex. Nondenaturing gel electrophoresis and glycerol gradient analyses demonstrate that while Prp31p may play a role in maintaining the assembly or stability of tri-snRNPs, functional protein is not essential for the formation of U4/U6 or U4/U6 x U5 snRNPs. These results suggest that Prp31p is involved in recruiting the U4/U6 x U5 tri-snRNP to prespliceosome complexes or in stabilizing these interactions.
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Affiliation(s)
- E M Weidenhammer
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
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7
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Gross T, Lützelberger M, Weigmann H, Klingenhoff A, Shenoy S, Käufer NF. Functional analysis of the fission yeast Prp4 protein kinase involved in pre-mRNA splicing and isolation of a putative mammalian homologue. Nucleic Acids Res 1997; 25:1028-35. [PMID: 9102632 PMCID: PMC146536 DOI: 10.1093/nar/25.5.1028] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The prp4 gene of Schizosaccharomyces pombe encodes a protein kinase. A physiological substrate is not yet known. A mutational analysis of prp4 revealed that the protein consists of a short N-terminal domain, containing several essential motifs, which is followed by the kinase catalytic domain comprising the C-terminus of the protein. Overexpression of N-terminal mutations disturbs mitosis and produces elongated cells, Using a PCR approach, we isolated a putative homologue of Prp4 from human and mouse cells. The mammalian kinase domain is 53% identical to the kinase domain of Prp4. The short N-terminal domains share <20% identical amino acids, but contain conserved motifs. A fusion protein consisting of the N-terminal region from S. pombe followed by the mammalian kinase domain complements a temperature-sensitive prp4 mutation of S. pombe. Prp4 and the recombinant yeast/mouse protein kinase phosphorylate the human SR splicing factor ASF/SF2 in vitro in its RS domain.
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Affiliation(s)
- T Gross
- Institüt für Genetik-Biozentrum, Technische Universität Braunschweig, Spielmannstrasse 7, D-38106 Braunschweig, Germany
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8
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Lewis JD, Izaurralde E, Jarmolowski A, McGuigan C, Mattaj IW. A nuclear cap-binding complex facilitates association of U1 snRNP with the cap-proximal 5' splice site. Genes Dev 1996; 10:1683-98. [PMID: 8682298 DOI: 10.1101/gad.10.13.1683] [Citation(s) in RCA: 179] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The mechanism by which intron-containing RNAs are recognized by the splicing machinery is only partly understood. A nuclear cap-binding complex (CBC), which specifically recognizes the monomethyl guanosine cap structure carried by RNA polymerase II transcripts, has previously been shown to play a role in pre-mRNA splicing. Using a combination of splicing complex and psoralen cross-linking analysis we demonstrate that CBC is required for efficient recognition of the 5' splice site by U1 snRNP during formation of E (early) complex on a pre-mRNA containing a single intron. However, in a pre-mRNA containing two introns, CBC is not required for splicing of the cap distal intron. In this case, the presence of an intact polypyrimidine tract in the cap-proximal intron renders splicing of the cap-distal intron independent of CBC. These results support models in which the splice sites in a pre-mRNA are originally recognized by interactions spanning exons. The defects in splicing and U1 snRNP binding caused by CBC depletion can be specifically reversed by recombinant CBC. In summary, efficient recognition of the cap-proximal 5' splice site by U1 snRNP is facilitated by CBC in what may be one of the earliest steps in pre-mRNA recognition. Data in Colot et al. (this issue) indicate that this function of CBC is conserved in humans and yeast.
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Affiliation(s)
- J D Lewis
- Gene Expression Programme, European Molecular Biology Laboratory, Heidelberg, Germany
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9
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Abstract
Advances over the past year have provided new insights into the mechanisms involved in the initial recognition and pairing of the 5' and 3' splice sites in complex metazoan pre-mRNAs. Highlights include the demonstration that exonic enhancers can promote trans splicing and that an excess of the serine and arginine rich family of splicing proteins can obviate the requirement for U1 small nuclear ribonucleoprotein particle in splicing.
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Affiliation(s)
- R Reed
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA.
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10
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Weidenhammer EM, Singh M, Ruiz-Noriega M, Woolford JL. The PRP31 gene encodes a novel protein required for pre-mRNA splicing in Saccharomyces cerevisiae. Nucleic Acids Res 1996; 24:1164-70. [PMID: 8604353 PMCID: PMC145753 DOI: 10.1093/nar/24.6.1164] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The pre-mRNA splicing factor Prp31p was identified in a screen of temperature-sensitive yeast strains for those exhibiting a splicing defect upon shift to the non- permissive temperature. The wild-type PRP31 gene was cloned and shown to be essential for cell viability. The PRP31 gene is predicted to encode a 60 kDa polypeptide. No similarities with other known splicing factors or motifs indicative of protein-protein or RNA-protein interaction domains are discernible in the predicted amino acid sequence. A PRP31 allele bearing a triple repeat of the hemagglutinin epitope has been generated. The tagged protein is functional in vivo and a single polypeptide species of the predicted size was detected by Western analysis with proteins from yeast cell extracts. Functional Prp31p is required for the processing of pre-mRNA species both in vivo and in vitro, indicating that the protein is directly involved in the splicing pathway.
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Affiliation(s)
- E M Weidenhammer
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213 USA
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11
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Yan D, Ares M. Invariant U2 RNA sequences bordering the branchpoint recognition region are essential for interaction with yeast SF3a and SF3b subunits. Mol Cell Biol 1996; 16:818-28. [PMID: 8622683 PMCID: PMC231062 DOI: 10.1128/mcb.16.3.818] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
U2 small nuclear RNA (snRNA) contains a sequence (GUAGUA) that pairs with the intron branchpoint during splicing. This sequence is contained within a longer invariant sequence of unknown secondary structure and function that extends between U2 and I and stem IIa. A part of this region has been proposed to pair with U6 in a structure called helix III. We made mutations to test the function of these nucleotides in yeast U2 snRNA. Most single base changes cause no obvious growth defects; however, several single and double mutations are lethal or conditional lethal and cause a block before the first step of splicing. We used U6 compensatory mutations to assess the contribution of helix III and found that if it forms, helix III is dispensable for splicing in Saccharomyces cerevisiae. On the other hand, mutations in known protein components of the splicing apparatus suppress or enhance the phenotypes of mutations within the invariant sequence that connect the branchpoint recognition sequence to stem IIa. Lethal mutations in the region are suppressed by Cus1-54p, a mutant yeast splicing factor homologous to a mammalian SF3b subunit. Synthetic lethal interactions show that this region collaborates with the DEAD-box protein Prp5p and the yeast SF3a subunits Prp9p, Prp11p, and Prp21p. Together, the data show that the highly conserved RNA element downstream of the branchpoint recognition sequence of U2 snRNA in yeast cells functions primarily with the proteins that make up SF3 rather than with U6 snRNA.
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Affiliation(s)
- D Yan
- Biology Department, Sinsheimer Laboratories, University of California, Santa Cruz 95064, USA
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12
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Samarsky DA, Balakin AG, Fournier MJ. Characterization of three new snRNAs from Saccharomyces cerevisiae: snR34, snR35 and snR36. Nucleic Acids Res 1995; 23:2548-54. [PMID: 7630735 PMCID: PMC307065 DOI: 10.1093/nar/23.13.2548] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Genes for three novel snRNAs of Saccharomyces cerevisiae have been isolated, sequenced and tested for essentiality. The RNAs encoded by these genes are designated snR34, snR35 and snR36 respectively and contain 203, 204 and 182 nucleotides. Each RNA is derived from a single copy gene and all three RNAs are believed to be nucleolar, i.e. snoRNAs, based on extraction properties and association with fibrillarin. SnR34 and snR35 contain a trimethylguanosine cap, but this feature is absent from snR36. The novel RNAs lack elements conserved among several other snoRNAs, including box C, box D and long sequence complementarities with rRNA. Genetic disruption analyses showed each of the RNAs to be dispensable and a haploid strain lacking all three RNAs and a previously characterized fourth snoRNA (snR33) is also viable. No differences in the levels of precursors or mature rRNAs were apparent in the four gene knock-out strain. Possible roles for the new RNAs in ribosome biogenesis are discussed.
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MESH Headings
- Alleles
- Base Sequence
- Blotting, Northern
- Cell Nucleolus/chemistry
- Chromosomal Proteins, Non-Histone/metabolism
- Cloning, Molecular
- Conserved Sequence
- DNA Restriction Enzymes
- Immunosorbent Techniques
- Molecular Sequence Data
- Mutagenesis
- RNA Caps/analysis
- RNA, Fungal/chemistry
- RNA, Fungal/genetics
- RNA, Fungal/isolation & purification
- RNA, Ribosomal/analysis
- RNA, Small Nuclear/chemistry
- RNA, Small Nuclear/genetics
- RNA, Small Nuclear/isolation & purification
- Saccharomyces cerevisiae/genetics
- Sequence Homology
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Affiliation(s)
- D A Samarsky
- Department of Biochemistry and Molecular Biology, Lederle Graduate Research Center, University of Massachusetts, Amherst 01002, USA
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13
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Furman E, Glitz DG. Purification of the spliceosome A-complex and its visualization by electron microscopy. J Biol Chem 1995; 270:15515-22. [PMID: 7797545 DOI: 10.1074/jbc.270.26.15515] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Pre-mRNA splicing occurs on spliceosomes, a family of ribonucleoprotein particles. Spliceosome assembly on exogenous adenovirus pre-mRNA was blocked at the A-complex (or pre-spliceosome) stage, either by destruction of the small nuclear ribonucleoproteins (snRNPs) that comprise the U4/U5/U6 tri-snRNP complex, or by interference in tri-snRNP assembly and interactions. The A-complex was isolated by size exclusion chromatography; homogeneity was shown by electrophoresis in nondenaturing polyacrylamide gels, gradient sedimentation, and electron microscopy. Northern hybridization showed U1 and U2 snRNAs to be present in the preparation, but not U4, U5, or U6. Antibodies specific for a component of the U1 snRNP or for a component that is common to all snRNPs (except U6) each precipitated an A-complex containing pre-mRNA, U1 and U2 snRNPs. Electron micrographs showed 230 x 270-A particles whose two components appear similar to individual U1 and U2 snRNPs. Electron micrographs of an A-complex-5'-biotinyl oligonucleotide-streptavidin-gold composite allowed identification of the U2 snRNP within the structure and the localization of the 5'-segment of U2 snRNA at a unique site in the A-complex. This region of U2 RNA is adjacent to the developing catalytic center of the spliceosome.
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Affiliation(s)
- E Furman
- Department of Biological Chemistry, UCLA School of Medicine, University of California 90024-1737, USA
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14
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Larsson SH, Charlieu JP, Miyagawa K, Engelkamp D, Rassoulzadegan M, Ross A, Cuzin F, van Heyningen V, Hastie ND. Subnuclear localization of WT1 in splicing or transcription factor domains is regulated by alternative splicing. Cell 1995; 81:391-401. [PMID: 7736591 DOI: 10.1016/0092-8674(95)90392-5] [Citation(s) in RCA: 358] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
WT1 is a tumor suppressor gene with a key role in urogenital development and the pathogenesis of Wilms' tumor. Two alternative splice sites in the WT1 transcript allow the gene to encode four proteins. These carry four Krüppel-type zinc fingers and to date have primarily been implicated in transcriptional control of genes involved in growth regulation. However, here we demonstrate colocalization of WT1 with splicing factors in the fetal kidney and testis and in expressing cell lines. Using immunoprecipitation, we show that two WT1 isoforms directly associate with one or a limited number of components in the spliceosomes and coiled bodies. Moreover, COS cell expression studies suggest that alternative splicing within the WT1 zinc finger region determines whether the protein localizes mainly with splicing factors or with DNA in transcription factor domains in the nucleus. We propose that WT1 plays roles in posttranscriptional processing of RNA as well as in transcription.
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Affiliation(s)
- S H Larsson
- Medical Research Council Human Genetics Unit, Western General Hospital, Edinburgh, Scotland
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15
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Shea JE, Toyn JH, Johnston LH. The budding yeast U5 snRNP Prp8 is a highly conserved protein which links RNA splicing with cell cycle progression. Nucleic Acids Res 1994; 22:5555-64. [PMID: 7838707 PMCID: PMC310116 DOI: 10.1093/nar/22.25.5555] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The dbf3 mutation was originally obtained in a screen for DNA synthesis mutants with a cell cycle phenotype in the budding yeast Saccharomyces cerevisiae. We have now isolated the DBF3 gene and found it to be an essential gene with an ORF of 7239 nucleotides, potentially encoding a large protein of 268 kDa. We also obtained an allele-specific high copy number suppressor of the dbf3-1 allele, encoded by the known SSB1 gene, a member of the Hsp70 family of heat shock proteins. The sequence of the Dbf3 protein is 58% identical over 2300 amino acid residues to a predicted protein from Caenorhabditis elegans. Furthermore, partial sequences with 61% amino acid sequence identity were deduced from two files of human cDNA in the EST nucleotide database so that Dbf3 is a highly conserved protein. The nucleotide sequence of DBF3 turned out to be identical to the yeast gene PRP8, which encodes a U5 snRNP required for pre-mRNA splicing. This surprising result led us to further characterise the phenotype of dbf3 which confirmed its role in the cell cycle and showed it to function early, around the time of S phase. This data suggests a hitherto unexpected link between pre-mRNA splicing and the cell cycle.
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Affiliation(s)
- J E Shea
- Laboratory of Yeast Genetics, National Institute for Medical Research, Mill Hill, London, UK
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