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Fukumura K, Venables JP, Mayeda A. SPF45/RBM17-dependent splicing and multidrug resistance to cancer chemotherapy. Mol Cell Oncol 2021; 8:1996318. [PMID: 35419480 PMCID: PMC8997263 DOI: 10.1080/23723556.2021.1996318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 10/10/2021] [Accepted: 10/13/2021] [Indexed: 06/14/2023]
Abstract
The early splicing complex A occupies at least eighty nucleotides of intron, in which U2AF covers the polypyrimidine tract. SPF45 (RBM17) functionally substitutes for U2AF on a subset of short introns. Since SPF45 expression confers resistance to various anticancer drugs, SPF45-dependent splicing may play a critical role in multidrug resistance.
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Affiliation(s)
- Kazuhiro Fukumura
- Division of Gene Expression Mechanism, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Aichi, Japan
| | - Julian P. Venables
- Science Sense, 2 Rue St Vincent, Salèlles du Bosc, 34700 Le Bosc, France
| | - Akila Mayeda
- Division of Gene Expression Mechanism, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Aichi, Japan
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2
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Campos N, Myburgh R, Garcel A, Vautrin A, Lapasset L, Nadal ES, Mahuteau-Betzer F, Najman R, Fornarelli P, Tantale K, Basyuk E, Séveno M, Venables JP, Pau B, Bertrand E, Wainberg MA, Speck RF, Scherrer D, Tazi J. Long lasting control of viral rebound with a new drug ABX464 targeting Rev - mediated viral RNA biogenesis. Retrovirology 2015; 12:30. [PMID: 25889234 PMCID: PMC4422473 DOI: 10.1186/s12977-015-0159-3] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Accepted: 03/24/2015] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Current therapies have succeeded in controlling AIDS pandemic. However, there is a continuing need for new drugs, in particular those acting through new and as yet unexplored mechanisms of action to achieve HIV infection cure. We took advantage of the unique feature of proviral genome to require both activation and inhibition of splicing of viral transcripts to develop molecules capable of achieving long lasting effect on viral replication in humanized mouse models through inhibition of Rev-mediated viral RNA biogenesis. RESULTS Current HIV therapies reduce viral load during treatment but titers rebound after treatment is discontinued. We devised a new drug that has a long lasting effect after viral load reduction. We demonstrate here that ABX464 compromises HIV replication of clinical isolates of different subtypes without selecting for drug resistance in PBMCs or macrophages. ABX464 alone, also efficiently compromised viral proliferation in two humanized mouse models infected with HIV that require a combination of 3TC, Raltegravir and Tenofovir (HAART) to achieve viral inhibition in current protocols. Crucially, while viral load increased dramatically just one week after stopping HAART treatment, only slight rebound was observed following treatment cessation with ABX464 and the magnitude of the rebound was maintained below to that of HAART for two months after stopping the treatment. Using a system to visualize single HIV RNA molecules in living cells, we show that ABX464 inhibits viral replication by preventing Rev-mediated export of unspliced HIV-1 transcripts to the cytoplasm and by interacting with the Cap Binding Complex (CBC). Deep sequencing of viral RNA from treated cells established that retained viral RNA is massively spliced but importantly, normal cellular splicing is unaffected by the drug. Consistently ABX464 is non-toxic in humans and therefore represents a promising complement to current HIV therapies. CONCLUSIONS ABX464 represents a novel class of anti-HIV molecules with unique properties. ABX464 has a long lasting effect in humanized mice and neutralizes the expression of HIV-1 proviral genome of infected immune cells including reservoirs and it is therefore a promising drug toward a functional cure of HIV.
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Affiliation(s)
- Noëlie Campos
- ABIVAX, 1919 route de Mende, 34293, Montpellier Cedex 5, France.
| | - Renier Myburgh
- Division of Infectious Diseases and Hospital Epidemiology Department of Internal Medicin, University of Zurich, University Hospital, Raemistrasse 100, 8091, Zurich, Switzerland.
| | - Aude Garcel
- ABIVAX, 1919 route de Mende, 34293, Montpellier Cedex 5, France.
| | - Audrey Vautrin
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS UMR 5535, 1919 route de Mende, 34293, Montpellier Cedex 5, France.
| | - Laure Lapasset
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS UMR 5535, 1919 route de Mende, 34293, Montpellier Cedex 5, France.
| | - Erika Schläpfer Nadal
- Division of Infectious Diseases and Hospital Epidemiology Department of Internal Medicin, University of Zurich, University Hospital, Raemistrasse 100, 8091, Zurich, Switzerland.
| | - Florence Mahuteau-Betzer
- Institut Curie, CNRS UMR9187, INSERM U1196, Centre universitaire, Bâtiment 110, 15 rue Georges Clémenceau, 91405, ORSAY CEDEX, France.
| | - Romain Najman
- ABIVAX, 1919 route de Mende, 34293, Montpellier Cedex 5, France.
| | | | - Katjana Tantale
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS UMR 5535, 1919 route de Mende, 34293, Montpellier Cedex 5, France.
| | - Eugénia Basyuk
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS UMR 5535, 1919 route de Mende, 34293, Montpellier Cedex 5, France.
| | - Martial Séveno
- Plate-forme de Protéomique Fonctionnelle (FPP) IGF, UMR 5203 CNRS - INSERM U661- UM, 141 rue de la Cardonille (pièce 029), 34094, Montpellier CEDEX 05, France.
| | - Julian P Venables
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS UMR 5535, 1919 route de Mende, 34293, Montpellier Cedex 5, France.
| | - Bernard Pau
- Université de Montpellier, UFR Pharmacie, 15 Avenue Charles Flahault, 34000, Montpellier, France.
| | - Edouard Bertrand
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS UMR 5535, 1919 route de Mende, 34293, Montpellier Cedex 5, France.
| | - Mark A Wainberg
- McGill AIDS Center, Lady Davis Institute - Jewish General Hospital, Montréal, QC, Canada.
| | - Roberto F Speck
- Division of Infectious Diseases and Hospital Epidemiology Department of Internal Medicin, University of Zurich, University Hospital, Raemistrasse 100, 8091, Zurich, Switzerland.
| | - Didier Scherrer
- ABIVAX, 1919 route de Mende, 34293, Montpellier Cedex 5, France.
| | - Jamal Tazi
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS UMR 5535, 1919 route de Mende, 34293, Montpellier Cedex 5, France.
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3
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Ehrmann I, Dalgliesh C, Liu Y, Danilenko M, Crosier M, Overman L, Arthur HM, Lindsay S, Clowry GJ, Venables JP, Fort P, Elliott DJ. The tissue-specific RNA binding protein T-STAR controls regional splicing patterns of neurexin pre-mRNAs in the brain. PLoS Genet 2013; 9:e1003474. [PMID: 23637638 PMCID: PMC3636136 DOI: 10.1371/journal.pgen.1003474] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Accepted: 03/07/2013] [Indexed: 11/18/2022] Open
Abstract
The RNA binding protein T-STAR was created following a gene triplication 520-610 million years ago, which also produced its two parologs Sam68 and SLM-1. Here we have created a T-STAR null mouse to identify the endogenous functions of this RNA binding protein. Mice null for T-STAR developed normally and were fertile, surprisingly, given the high expression of T-STAR in the testis and the brain, and the known infertility and pleiotropic defects of Sam68 null mice. Using a transcriptome-wide search for splicing targets in the adult brain, we identified T-STAR protein as a potent splicing repressor of the alternatively spliced segment 4 (AS4) exons from each of the Neurexin1-3 genes, and exon 23 of the Stxbp5l gene. T-STAR protein was most highly concentrated in forebrain-derived structures like the hippocampus, which also showed maximal Neurexin1-3 AS4 splicing repression. In the absence of endogenous T-STAR protein, Nrxn1-3 AS4 splicing repression dramatically decreased, despite physiological co-expression of Sam68. In transfected cells Neurexin3 AS4 alternative splicing was regulated by either T-STAR or Sam68 proteins. In contrast, Neurexin2 AS4 splicing was only regulated by T-STAR, through a UWAA-rich response element immediately downstream of the regulated exon conserved since the radiation of bony vertebrates. The AS4 exons in the Nrxn1 and Nrxn3 genes were also associated with distinct patterns of conserved UWAA repeats. Consistent with an ancient mechanism of splicing control, human T-STAR protein was able to repress splicing inclusion of the zebrafish Nrxn3 AS4 exon. Although Neurexin1-3 and Stxbp5l encode critical synaptic proteins, T-STAR null mice had no detectable spatial memory deficits, despite an almost complete absence of AS4 splicing repression in the hippocampus. Our work identifies T-STAR as an ancient and potent tissue-specific splicing regulator that uses a concentration-dependent mechanism to co-ordinately regulate regional splicing patterns of the Neurexin1-3 AS4 exons in the mouse brain.
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Affiliation(s)
- Ingrid Ehrmann
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Caroline Dalgliesh
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Yilei Liu
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Marina Danilenko
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Moira Crosier
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Lynn Overman
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Helen M. Arthur
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Susan Lindsay
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Gavin J. Clowry
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Julian P. Venables
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Philippe Fort
- Universités Montpellier 2 et 1, UMR 5237, Centre de Recherche de Biochimie Macromoléculaire, CNRS, Montpellier, France
| | - David J. Elliott
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom
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4
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Abstract
Alternative splicing expands the coding capacity of metazoan genes, and it was largely genetic studies in the fruit-fly Drosophila melanogaster that established the principle that regulated alternative splicing results in tissue- and stage-specific protein isoforms with different functions in development. Alternative splicing is particularly prominent in germ cells, muscle and the central nervous system where it modulates the expression of various proteins including cell-surface molecules and transcription factors. Studies in flies have given us numerous insights into alternative splicing in terms of upstream regulation, the exquisite diversity of their forms and the key differential cellular functions of alternatively spliced gene products. The current inundation of transcriptome sequencing data from Drosophila provides an unprecedented opportunity to gain a comprehensive view of alternative splicing.
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Affiliation(s)
- Julian P Venables
- Université Montpellier 2, UMR 5535, Institut de Génétique Moléculaire de Montpellier, CNRS, 1919 Route de Mende, 34293 Montpellier cedex 05, France
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Venables JP, Klinck R, Koh C, Gervais-Bird J, Bramard A, Inkel L, Durand M, Couture S, Froehlich U, Lapointe E, Lucier JF, Thibault P, Rancourt C, Tremblay K, Prinos P, Chabot B, Elela SA. Cancer-associated regulation of alternative splicing. Nat Struct Mol Biol 2009; 16:670-6. [PMID: 19448617 DOI: 10.1038/nsmb.1608] [Citation(s) in RCA: 275] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2009] [Accepted: 04/21/2009] [Indexed: 02/06/2023]
Abstract
Alternative splicing of pre-mRNA increases the diversity of protein functions. Here we show that about half of all active alternative splicing events in ovarian and breast tissues are changed in tumors, and many seem to be regulated by a single factor; sequence analysis revealed binding sites for the RNA binding protein FOX2 downstream of one-third of the exons skipped in cancer. High-resolution analysis of FOX2 binding sites defined the precise positions relative to alternative exons at which the protein may function as either a silencer or an enhancer. Most of the identified targets were shifted in the same direction by FOX2 depletion in cell lines as they were in breast and ovarian cancer tissues. Notably, we found expression of FOX2 itself is downregulated in ovarian cancer and its splicing is altered in breast cancer samples. These results suggest that the decreased expression of FOX2 in cancer tissues modulates splicing and controls proliferation.
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Affiliation(s)
- Julian P Venables
- Laboratoire de génomique fonctionnelle de l'Université de Sherbrooke, Sherbrooke, Québec, Canada
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6
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Venables JP, Klinck R, Bramard A, Inkel L, Dufresne-Martin G, Koh C, Gervais-Bird J, Lapointe E, Froehlich U, Durand M, Gendron D, Brosseau JP, Thibault P, Lucier JF, Tremblay K, Prinos P, Wellinger RJ, Chabot B, Rancourt C, Elela SA. Identification of alternative splicing markers for breast cancer. Cancer Res 2008; 68:9525-31. [PMID: 19010929 DOI: 10.1158/0008-5472.can-08-1769] [Citation(s) in RCA: 140] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Breast cancer is the most common cause of cancer death among women under age 50 years, so it is imperative to identify molecular markers to improve diagnosis and prognosis of this disease. Here, we present a new approach for the identification of breast cancer markers that does not measure gene expression but instead uses the ratio of alternatively spliced mRNAs as its indicator. Using a high-throughput reverse transcription-PCR-based system for splicing annotation, we monitored the alternative splicing profiles of 600 cancer-associated genes in a panel of 21 normal and 26 cancerous breast tissues. We validated 41 alternative splicing events that significantly differed in breast tumors relative to normal breast tissues. Most cancer-specific changes in splicing that disrupt known protein domains support an increase in cell proliferation or survival consistent with a functional role for alternative splicing in cancer. In a blind screen, a classifier based on the 12 best cancer-associated splicing events correctly identified cancer tissues with 96% accuracy. Moreover, a subset of these alternative splicing events could order tissues according to histopathologic grade, and 5 markers were validated in a further blind set of 19 grade 1 and 19 grade 3 tumor samples. These results provide a simple alternative for the classification of normal and cancerous breast tumor tissues and underscore the putative role of alternative splicing in the biology of cancer.
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Affiliation(s)
- Julian P Venables
- Laboratoire de génomique fonctionnelle de l'Université de Sherbrooke, Québec, Canada
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7
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Venables JP, Koh CS, Froehlich U, Lapointe E, Couture S, Inkel L, Bramard A, Paquet ER, Watier V, Durand M, Lucier JF, Gervais-Bird J, Tremblay K, Prinos P, Klinck R, Elela SA, Chabot B. Multiple and specific mRNA processing targets for the major human hnRNP proteins. Mol Cell Biol 2008; 28:6033-43. [PMID: 18644864 PMCID: PMC2547008 DOI: 10.1128/mcb.00726-08] [Citation(s) in RCA: 122] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2008] [Revised: 05/30/2008] [Accepted: 07/11/2008] [Indexed: 12/22/2022] Open
Abstract
Alternative splicing is a key mechanism regulating gene expression, and it is often used to produce antagonistic activities particularly in apoptotic genes. Heterogeneous nuclear ribonucleoparticle (hnRNP) proteins form a family of RNA-binding proteins that coat nascent pre-mRNAs. Many but not all major hnRNP proteins have been shown to participate in splicing control. The range and specificity of hnRNP protein action remain poorly documented, even for those affecting splice site selection. We used RNA interference and a reverse transcription-PCR screening platform to examine the implications of 14 of the major hnRNP proteins in the splicing of 56 alternative splicing events in apoptotic genes. Out of this total of 784 alternative splicing reactions tested in three human cell lines, 31 responded similarly to a knockdown in at least two different cell lines. On the other hand, the impact of other hnRNP knockdowns was cell line specific. The broadest effects were obtained with hnRNP K and C, two proteins whose role in alternative splicing had not previously been firmly established. Different hnRNP proteins affected distinct sets of targets with little overlap even between closely related hnRNP proteins. Overall, our study highlights the potential contribution of all of these major hnRNP proteins in alternative splicing control and shows that the targets for individual hnRNP proteins can vary in different cellular contexts.
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Affiliation(s)
- Julian P Venables
- Département de Microbiologie et d'Infectiologie, Faculté de Médecine et des Sciences de la Santé, 3001, 12th Avenue Nord, Université de Sherbrooke, Sherbrooke, Québec J1H 5N4, Canada
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8
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Klinck R, Bramard A, Inkel L, Dufresne-Martin G, Gervais-Bird J, Madden R, Paquet ER, Koh C, Venables JP, Prinos P, Jilaveanu-Pelmus M, Wellinger R, Rancourt C, Chabot B, Abou Elela S. Multiple alternative splicing markers for ovarian cancer. Cancer Res 2008; 68:657-63. [PMID: 18245464 DOI: 10.1158/0008-5472.can-07-2580] [Citation(s) in RCA: 126] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Intense efforts are currently being directed toward profiling gene expression in the hope of developing better cancer markers and identifying potential drug targets. Here, we present a sensitive new approach for the identification of cancer signatures based on direct high-throughput reverse transcription-PCR validation of alternative splicing events. This layered and integrated system for splicing annotation (LISA) fills a gap between high-throughput microarray studies and high-sensitivity individual gene investigations, and was created to monitor the splicing of 600 cancer-associated genes in 25 normal and 21 serous ovarian cancer tissues. Out of >4,700 alternative splicing events screened, the LISA identified 48 events that were significantly associated with serous ovarian tumor tissues. In a further screen directed at 39 ovarian tissues containing cancer pathologies of various origins, our ovarian cancer splicing signature successfully distinguished all normal tissues from cancer. High-volume identification of cancer-associated splice forms by the LISA paves the way for the use of alternative splicing profiling to diagnose subtypes of cancer.
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Affiliation(s)
- Roscoe Klinck
- Laboratoire de génomique fonctionnelle de l'Université de Sherbrooke, Université de Sherbrooke, Sherbrooke, Québec, Canada
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9
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Venables JP. Enrichment of alternatively spliced isoforms. Methods Mol Biol 2008; 419:161-170. [PMID: 18369982 DOI: 10.1007/978-1-59745-033-1_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Most metazoan genes are alternatively spliced, and a large number of alternatively spliced isoforms are likely to be functionally significant and expressed at specific stages of pathogenesis or differentiation. Splicing changes usually only affect a small portion of a gene, and these changes may cause significant mRNA degradation. After RT-PCR, minor variants can form heteroduplexes with the major variants. Affinity purification of these heteroduplexes using immobilized Thermus aquaticus single-stranded DNA-binding protein allows purification of alternative splice forms in a 1:1 ratio, which makes it easy to sequence the rare form. This chapter provides a detailed protocol of the technique I have developed to identify spliced isoforms called enrichment of alternatively spliced isoforms or EASI.
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Affiliation(s)
- Julian P Venables
- Laboratoire de génomique fonctionnelle de l'Université de Sherbrooke Centre de développement des biotechologies (CDB) de Sherbrooke, Québec, Canada
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10
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Abstract
Alternative splicing leads to multiple proteins from individual genes and the most common deviation from the norm is precise exon omission. Mutations that cause this can be found deep in introns, especially downstream of the cassette exon. This review summarises what is known about these intronic splicing enhancers and their RNA-binding proteins that cause spliceosome assembly on the upstream exon.
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Affiliation(s)
- Julian P Venables
- Laboratoire de Génomique Fonctionnelle de l'Université de Sherbrooke, Centre de Développement des Biotechnologies (CDB) de Sherbrooke 3201, Rue Jean-Mignault, Sherbrooke, Québec, Canada.
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11
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Morrison AA, Venables JP, Dellaire G, Ladomery MR. The Wilms tumour suppressor protein WT1 (+KTS isoform) binds alpha-actinin 1 mRNA via its zinc-finger domain. Biochem Cell Biol 2007; 84:789-98. [PMID: 17167543 DOI: 10.1139/o06-065] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mutations in WT1 are associated with developmental syndromes that affect the urogenital system and neoplasms, including Wilms tumour, acute myeloid leukemia, and breast and prostate cancers. The WT1 protein belongs to the early growth response family of zinc-finger transcription factors. Uniquely to WT1, an evolutionarily conserved alternative splice event inserts the tripeptide KTS, between zinc fingers 3 and 4. Whereas -KTS isoforms bind DNA and activate or repress transcription, +KTS isoforms bind DNA less efficiently and interact with splice factors and RNA in vitro and in vivo. Although candidate DNA targets have been found, physiological mRNA targets are yet to be defined. We examined the distribution of WT1 in ribonucleoprotein (RNP) complexes in nuclear extract prepared from M15 cells, a mouse mesonephric fetal kidney cell line. WT1 cofractionated with the splice factor PSF in large RNP particles >or=2 MDa. We also found that PSF co-immunoprecipitated with WT1, suggesting a functional interaction between these 2 multifunctional proteins. Using yeast three-hybrid library constructed from the co-immunoprecipitated RNA we found that WT1 (+KTS) binds close to or at the start codon of alpha-actinin 1 (ACTN1) mRNA. A band shift assay confirmed the ability of the WT1 zinc-finger domain (+KTS) to bind this sequence in vitro. ACTN1 is the first likely physiological mRNA target of WT1.
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Affiliation(s)
- A A Morrison
- Bristol Genomics Research Institute, Faculty of Applied Sciences, University of the West of England, Coldharbour Lane, Bristol BS16 1QY, UK
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12
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Sergeant KA, Bourgeois CF, Dalgliesh C, Venables JP, Stevenin J, Elliott DJ. Alternative RNA splicing complexes containing the scaffold attachment factor SAFB2. J Cell Sci 2007; 120:309-19. [PMID: 17200140 DOI: 10.1242/jcs.03344] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The scaffold attachment factor SAFB1 and its recently discovered homologue SAFB2 might provide an important link between pre-mRNA splicing, intracellular signalling and transcription. Using novel mono-specific antisera, we found endogenous SAFB2 protein has a different spatial distribution from SAFB1 within the nucleus where it is found in much larger nuclear complexes (up to 670 kDa in size), and a distinct pattern of expression in adult human testis. By contrast, SAFB1 protein predominantly exists either as smaller complexes or as a monomeric protein. Our results suggest stable core complexes containing components comprised of SAFB1, SAFB2 and the RNA binding proteins Sam68 and hnRNPG exist in parallel with free SAFB1 protein. We found that SAFB2 protein, like SAFB1, acts as a negative regulator of a tra2β variable exon. Despite showing an involvement in splicing, we detected no stable interaction between SAFB proteins and SR or SR-related splicing regulators, although these were also found in stable higher molecular mass complexes. Each of the detected alternative splicing regulator complexes exists independently of intact nucleic acids, suggesting they might be pre-assembled and recruited to nascent transcripts as modules to facilitate alternative splicing, and/or they represent nuclear storage compartments from which active proteins are recruited.
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Affiliation(s)
- Kate A Sergeant
- Institute of Human Genetics, University of Newcastle, International Centre for Life, Central Parkway, Newcastle, NE1 3BZ, UK
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13
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Venables JP, Strain L, Routledge D, Bourn D, Powell HM, Warwicker P, Diaz-Torres ML, Sampson A, Mead P, Webb M, Pirson Y, Jackson MS, Hughes A, Wood KM, Goodship JA, Goodship THJ. Atypical haemolytic uraemic syndrome associated with a hybrid complement gene. PLoS Med 2006; 3:e431. [PMID: 17076561 PMCID: PMC1626556 DOI: 10.1371/journal.pmed.0030431] [Citation(s) in RCA: 164] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2006] [Accepted: 08/16/2006] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Sequence analysis of the regulators of complement activation (RCA) cluster of genes at chromosome position 1q32 shows evidence of several large genomic duplications. These duplications have resulted in a high degree of sequence identity between the gene for factor H (CFH) and the genes for the five factor H-related proteins (CFHL1-5; aliases CFHR1-5). CFH mutations have been described in association with atypical haemolytic uraemic syndrome (aHUS). The majority of the mutations are missense changes that cluster in the C-terminal region and impair the ability of factor H to regulate surface-bound C3b. Some have arisen as a result of gene conversion between CFH and CFHL1. In this study we tested the hypothesis that nonallelic homologous recombination between low-copy repeats in the RCA cluster could result in the formation of a hybrid CFH/CFHL1 gene that predisposes to the development of aHUS. METHODS AND FINDINGS In a family with many cases of aHUS that segregate with the RCA cluster we used cDNA analysis, gene sequencing, and Southern blotting to show that affected individuals carry a heterozygous CFH/CFHL1 hybrid gene in which exons 1-21 are derived from CFH and exons 22/23 from CFHL1. This hybrid encodes a protein product identical to a functionally significant CFH mutant (c.3572C>T, S1191L and c.3590T>C, V1197A) that has been previously described in association with aHUS. CONCLUSIONS CFH mutation screening is recommended in all aHUS patients prior to renal transplantation because of the high risk of disease recurrence post-transplant in those known to have a CFH mutation. Because of our finding it will be necessary to implement additional screening strategies that will detect a hybrid CFH/CFHL1 gene.
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Affiliation(s)
- Julian P Venables
- Institute of Human Genetics, University of Newcastle upon Tyne, Newcastle upon Tyne, United Kingdom
| | - Lisa Strain
- Northern Molecular Genetics Service Laboratory, Newcastle upon Tyne Hospitals National Health Service Trust, Newcastle upon Tyne, United Kingdom
| | - Danny Routledge
- Northern Molecular Genetics Service Laboratory, Newcastle upon Tyne Hospitals National Health Service Trust, Newcastle upon Tyne, United Kingdom
| | - David Bourn
- Northern Molecular Genetics Service Laboratory, Newcastle upon Tyne Hospitals National Health Service Trust, Newcastle upon Tyne, United Kingdom
| | - Helen M Powell
- Northern Molecular Genetics Service Laboratory, Newcastle upon Tyne Hospitals National Health Service Trust, Newcastle upon Tyne, United Kingdom
| | - Paul Warwicker
- Renal Unit, East and North Hertfordshire National Health Service Trust, Stevenage, United Kingdom
| | - Martha L Diaz-Torres
- Institute of Human Genetics, University of Newcastle upon Tyne, Newcastle upon Tyne, United Kingdom
| | - Anne Sampson
- Department of Immunology, Newcastle upon Tyne Hospitals National Health Service Trust, Newcastle upon Tyne, United Kingdom
| | - Paul Mead
- Renal Unit, North Cumbria Acute Hospitals National Health Service Trust, Carlisle, United Kingdom
| | - Michelle Webb
- Renal Unit, East Kent Hospitals National Health Service Trust, Canterbury, United Kingdom
| | - Yves Pirson
- Service de Nephrologie, Cliniques Universitaires Saint-Luc, Brussels, Belgium
| | - Michael S Jackson
- Institute of Human Genetics, University of Newcastle upon Tyne, Newcastle upon Tyne, United Kingdom
| | - Anne Hughes
- Department of Medical Genetics, Queen's University, Belfast, United Kingdom
| | - Katrina M Wood
- Department of Histopathology, Newcastle upon Tyne Hospitals National Health Service Trust, Newcastle upon Tyne, United Kingdom
| | - Judith A Goodship
- Institute of Human Genetics, University of Newcastle upon Tyne, Newcastle upon Tyne, United Kingdom
| | - Timothy H. J Goodship
- Institute of Human Genetics, University of Newcastle upon Tyne, Newcastle upon Tyne, United Kingdom
- * To whom correspondence should be addressed. E-mail:
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14
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Abstract
Alternative splicing produces more than one protein from the majority of genes and the rarer forms can have dominant functions. Instability of alternative transcripts can also hinder the study of regulation of gene expression by alternative splicing. To investigate the true extent of alternative splicing we have developed a simple method of enriching alternatively spliced isoforms (EASI) from PCRs using beads charged with Thermus aquaticus single-stranded DNA-binding protein (T.Aq ssb). This directly purifies the single-stranded regions of heteroduplexes between alternative splices formed in the PCR, enabling direct sequencing of all the rare alternative splice forms of any gene. As a proof of principle the alternative transcripts of three tumour suppressor genes, TP53, MLH1 and MSH2, were isolated from testis cDNA. These contain missing exons, cryptic splice sites or include completely novel exons. EASI beads are stable for months in the fridge and can be easily combined with standard protocols to speed the cloning of novel transcripts.
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Affiliation(s)
- Julian P Venables
- Institute of Human Genetics, International Centre for Life, Central Parkway, University of Newcastle-upon-Tyne, Newcastle-upon-Tyne, UK.
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15
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Thornton JK, Dalgleish C, Venables JP, Sergeant KA, Ehrmann IE, Lu X, Saunders PTK, Elliott DJ. The tumour-suppressor protein ASPP1 is nuclear in human germ cells and can modulate ratios of CD44 exon V5 spliced isoforms in vivo. Oncogene 2006; 25:3104-12. [PMID: 16474851 DOI: 10.1038/sj.onc.1209341] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The ASPP1 (Apoptosis Stimulating Protein of p53) protein is an important tumour-suppressor. We have detected a novel protein interaction between the human ASPP1 (hASPP1) protein and the predominantly nuclear adaptor protein SAM68. In the human testis, full-length endogenous hASPP1 protein is located in the nucleus like SAM68, predominantly within meiotic and postmeiotic cells. Mouse ASPP1 (mASPP1) protein is mainly expressed in the brain and testis. The interaction with nuclear SAM68 is likely to be restricted to human germ cells, since endogenous mASPP1 protein is exclusively cytoplasmic. The C-terminal region of hASPP1 efficiently targeted a fused GFP molecule to the nucleus, whereas the N-terminus of hASPP1 targeted GFP to the cytoplasm. In the context of the full-length molecule this cytoplasmic targeting sequence is dominant in HEK293 and Saos-2 cells, since full-length hASPP1-GFP is almost exclusively cytoplasmic. Despite its predominantly cytoplasmic location, we show that ASPP1-GFP expression in HEK293 cells can regulate the ratio of alternative spliced isoforms derived from a pre-mRNA regulated downstream of cytoplasmic signalling pathways, and our data suggest that ASPP1 may operate in this case downstream or parallel to RAS signalling pathways.
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Affiliation(s)
- J K Thornton
- Institute of Human Genetics, University of Newcastle, International Centre for Life, Central Parkway, Newcastle, UK
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16
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Abstract
Alternative pre-mRNA splicing leads to distinct products of gene expression in development and disease. Antagonistic splice variants of genes involved in differentiation, apoptosis, invasion and metastasis often exist in a delicate equilibrium that is found to be perturbed in tumours. In several recent examples, splice variants that are overexpressed in cancer are expressed as hyper-oncogenic proteins, which often correlate with poor prognosis, thus suggesting improved diagnosis and follow up treatment. Global gene expression technologies are just beginning to decipher the interplay between alternatively spliced isoforms and protein-splicing factors that will lead to identification of the mutations in these trans-acting factors responsible for pathogenic alternative splicing in cancer.
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Affiliation(s)
- Julian P Venables
- University of Newcastle-upon-Tyne, Institute of Human Genetics, International Centre for Life, Central Parkway, Newcastle-upon-Tyne, UK.
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17
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Venables JP, Bourgeois CF, Dalgliesh C, Kister L, Stevenin J, Elliott DJ. Up-regulation of the ubiquitous alternative splicing factor Tra2β causes inclusion of a germ cell-specific exon. Hum Mol Genet 2005; 14:2289-303. [PMID: 16000324 DOI: 10.1093/hmg/ddi233] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
We have discovered a new exon of the homeodomain-interacting kinase HipK3 that incorporates a premature stop codon and is included only in the human testis. To investigate this, we tested the effects of transfecting cells with green fluorescent protein fusions of RNA-binding proteins implicated in spermatogenesis using a novel assay based on multi-fraction fluorescence-activated cell sorting (MF-FACS). This allows the effect of a controlled titration of any splicing factor on the splicing of endogenous genes to be studied in vivo. We found that Tra2beta recapitulates testis-specific splicing of endogenous HipK3 in a concentration-dependent manner and binds specifically to a long purine-rich sequence in the novel exon. This sequence was also specifically bound by hnRNP A1, hnRNP H, ASF/SF2 and SRp40, but not by 9G8. Consistent with these observations, in vitro studies showed that this sequence shifts splicing to a downstream 5' splice site within a heterologous pre-mRNA substrate in the presence of Tra2beta, ASF/SF2 and SRp40, whereas hnRNP A1 specifically inhibits this choice. By mutating the purine-rich sequence in the context of the HipK3 gene, we also show that it is the major determinant of Tra2beta- and hnRNP A1-mediated regulation. Tra2 is essential for sex determination and spermatogenesis in flies, and Tra2beta protein was most highly expressed in testis out of six mouse tissues, whereas hnRNP A1 is down-regulated during germ cell development. Therefore, our data imply an evolutionarily conserved role for Tra2 proteins in spermatogenesis and suggest that an elevated concentration of Tra2beta may convert it into a tissue-specific splicing factor.
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Affiliation(s)
- Julian P Venables
- Institute of Human Genetics, University of Newcastle upon Tyne, International Centre for Life, Central Parkway, Newcastle upon Tyne NE1 3BZ, UK.
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18
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Abstract
Pre-mRNA splicing is a sophisticated and ubiquitous nuclear process, which is a natural source of cancer-causing errors in gene expression. Intronic splice site mutations of tumor suppressor genes often cause exon-skipping events that truncate proteins just like classical nonsense mutations. Also, many studies over the last 20 years have reported cancer-specific alternative splicing in the absence of genomic mutations. Affected proteins include transcription factors, cell signal transducers, and components of the extracellular matrix. Antibodies against alternatively spliced products on cancer cells are currently in clinical trials, and competitive reverse transcription-PCR across regions of alternative splicing is being used as a simple diagnostic test. As well as being associated with cancer, the nature of the alternative gene products is usually consistent with an active role in cancer; therefore, the alternative splicing process itself is a potential target for gene therapy.
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Affiliation(s)
- Julian P Venables
- University of Newcastle-upon-Tyne, Institute of Human Genetics, International Centre for Life, Central Parkway, Newcastle-upon-Tyne, United Kingdom.
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19
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Venables JP, Dalgliesh C, Paronetto MP, Skitt L, Thornton JK, Saunders PT, Sette C, Jones KT, Elliott DJ. SIAH1 targets the alternative splicing factor T-STAR for degradation by the proteasome. Hum Mol Genet 2004; 13:1525-34. [PMID: 15163637 DOI: 10.1093/hmg/ddh165] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
T-STAR is one of three members of the SAM68 family of RNA-binding proteins that have been shown to be involved in various gene expression pathways including the control of pre-mRNA splicing. We employed a two-hybrid screen to identify proteins that interact with human T-STAR. The predominant interacting proteins were the E3 ubiquitin ligases SIAH1 and SIAH2. We found that SIAH1 bound to an octapeptide sequence in T-STAR targeting it for proteasome-dependent degradation. Rodent T-STAR orthologues (also known as etoile or SLM2) were not targeted for degradation by SIAH1. However a double amino acid substitution of mouse T-STAR that mimics the human SIAH1-binding site brought mouse T-STAR under in vivo control of SIAH1. Using a minigene transfection assay for alternative splicing activity we showed that human T-STAR, like its rodent orthologues can influence splice site choice and that human, but not mouse, T-STAR-dependent alternative splicing is modulated by SIAH1. Western blots of protein from purified germ cells indicated that SIAH1 protein expression peaks in meiosis. In mouse, T-STAR is co-expressed with SIAH1 during meiosis but, in humans, T-STAR is only strongly expressed after meiosis. Comparative sequence analysis showed SIAH-mediated proteasomal degradation of T-STAR has evolved in the primate lineage. Collectively these data suggest that SIAH-mediated down regulation of alternative splicing may be an important developmental difference between otherwise highly conserved T-STAR proteins.
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Affiliation(s)
- Julian P Venables
- Institute of Human Genetics, International Centre for Life, Newcastle upon Tyne, UK
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20
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Hyslop LA, Nixon VL, Levasseur M, Chapman F, Chiba K, McDougall A, Venables JP, Elliott DJ, Jones KT. Ca2+-promoted cyclin B1 degradation in mouse oocytes requires the establishment of a metaphase arrest. Dev Biol 2004; 269:206-19. [PMID: 15081368 DOI: 10.1016/j.ydbio.2004.01.030] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2003] [Revised: 01/22/2004] [Accepted: 01/27/2004] [Indexed: 02/05/2023]
Abstract
CDK1-cyclin B1 is a universal cell cycle kinase required for mitotic/meiotic cell cycle entry and its activity needs to decline for mitotic/meiotic exit. During their maturation, mouse oocytes proceed through meiosis I and arrest at second meiotic metaphase with high CDK1-cyclin B1 activity. Meiotic arrest is achieved by the action of a cytostatic factor (CSF), which reduces cyclin B1 degradation. Meiotic arrest is broken by a Ca2+ signal from the sperm that accelerates it. Here we visualised degradation of cyclin B1::GFP in oocytes and found that its degradation rate was the same for both meiotic divisions. Ca2+ was the necessary and sufficient trigger for cyclin B1 destruction during meiosis II; but it played no role during meiosis I and furthermore could not accelerate cyclin B1 destruction during this time. The ability of Ca2+ to trigger cyclin B1 destruction developed in oocytes following a restabilisation of cyclin B1 levels at about 12 h of culture. This was independent of actual first polar body extrusion. Thus, in metaphase I arrested oocytes, Ca2+ would induce cyclin B1 destruction and the first polar body would be extruded. In contrast to some reports in lower species, we found no evidence that oocyte activation was associated with an increase in 26S proteasome activity. We therefore conclude that Ca2+ mediates cyclin B1 degradation by increasing the activity of an E3 ubiquitin ligase. However, this stimulation occurs only in the presence of the ubiquitin ligase inhibitor CSF. We propose a model in which Ca2+ directly stimulates destruction of CSF during mammalian fertilisation.
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Affiliation(s)
- Louise A Hyslop
- Cell and Developmental Physiology Research Group, School of Cell and Molecular Biosciences, The Medical School, University of Newcastle, Newcastle NE2 4HH, UK
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21
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Paronetto MP, Venables JP, Elliott DJ, Geremia R, Rossi P, Sette C. tr-kit promotes the formation of a multimolecular complex composed by Fyn, PLCγ1 and Sam68. Oncogene 2003; 22:8707-15. [PMID: 14647465 DOI: 10.1038/sj.onc.1207016] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Tr-kit is a truncated form of the tyrosine kinase receptor c-kit expressed in the haploid phase of spermatogenesis. Upon microinjection, tr-kit triggers metaphase-to-anaphase transition in mouse eggs by the sequential activation of Fyn and PLCgamma1. Here, we show that tr-kit promotes the interaction of several tyrosine-phosphorylated proteins with the SH3 domain of PLCgamma1. Western blot analysis indicates that one of these proteins is Sam68, an RNA-binding protein that is known to interact with and be phosphorylated by Src-like kinases in mitosis. tr-kit promotes the association of Sam68 with PLCgamma1 and Fyn in a multimolecular complex, as demonstrated by co-immunoprecipitation of the phosphorylated forms of these proteins using antibodies directed to anyone of the partners of the complex. Expression of tr-kit potentiates the interaction of endogenous Sam68 also with the SH3 domain of Fyn. Furthermore, the subcellular localization of Sam68 is affected by tr-kit through activation of Fyn in live cells. Lastly, we show that interaction with the SH3 domain of Fyn triggers the release of Sam68 from bound RNA. Thus, our data suggest that tr-kit promotes the formation of a multimolecular complex composed of Fyn, PLCgamma1 and Sam68, which allows phosphorylation of PLCgamma1 by Fyn, and may modulate RNA metabolism.
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Affiliation(s)
- Maria Paola Paronetto
- Department of Public Health and Cell Biology, Section of Anatomy, University of Rome 'Tor Vergata', Rome, Italy
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22
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Abstract
Germ-cell differentiation is an ideal process for studying the effects of alternative splicing and there are examples of alternative splicing of genes involved in gene regulation and signal transduction at every stage of the spermatogenic pathway. A network of testes-specific splicing factor interactions has been uncovered and combining our knowledge of these RNAs and proteins should lead to an understanding of the regulation of alternative splicing and male fertility.
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Affiliation(s)
- Julian P Venables
- Institute of Human Genetics, University of Newcastle upon Tyne, International Centre for Life, Central Parkway, Newcastle upon Tyne NE1 3BZ, UK.
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23
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Abstract
DAZ is an RNA-binding protein encoded by a region on the Y chromosome implicated in infertility, and DAZ-like (Dazl) proteins are master regulators of germ line gene expression in all animals. In mice Dazl is only expressed in germ cells and is necessary for meiosis. A dual approach was taken to understand the RNA-binding specificity of the Dazl protein: (i) traditional SELEX and (ii) a novel tri-hybrid screen. Both approaches led to the same conclusion, namely that Dazl binds oligo(U) stretches interspersed by G or C residues. In a directed tri-hybrid assay the strongest interaction was with the consensus (GUn)n. This motif is found in the 5' UTR of CDC25C whose homologue is thought to be the target of Boule, the Dazl homologue in flies. CDC25C 5' UTR also interacted specifically with Dazl in vitro. The tri-hybrid screen retrieved UTRs of known genes that may be physiological substrates of Dazl.
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Affiliation(s)
- J P Venables
- Medical Research Council Human Genetics Unit, Western General Hospital, Crewe Road, Edinburgh EH4 2XU, UK.
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24
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Abstract
This review concentrates on the clear cases where knocking out a gene in mice has caused male infertility and thus comes near to proving that the gene plays a role in the development of sperm. Knockout mice have been created with primary defects at every stage of spermatogenesis thus creating a framework for decoding the genetic hierarchy that causes male germ cell differentiation. As well as defining essential genes in vivo experiments have defined promoter and untranslated sequences responsible for the expression of proteins at all the spermatogenic stages. In conclusion knockout mice remain the ultimate test of spermatogenic hypotheses as well as providing detailed information about this complex process.
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Affiliation(s)
- J P Venables
- Medical Research Council, Human Genetics Unit, Western General Hospital, Edinburgh, UK.
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25
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Elliott DJ, Venables JP, Newton CS, Lawson D, Boyle S, Eperon IC, Cooke HJ. An evolutionarily conserved germ cell-specific hnRNP is encoded by a retrotransposed gene. Hum Mol Genet 2000; 9:2117-24. [PMID: 10958650 DOI: 10.1093/hmg/9.14.2117] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The gene encoding heterogeneous ribonucleoprotein (hnRNP) G recently has been mapped to the X chromosome. All mammals have a Y chromosome-encoded homologue of HNRNP G called RBMY, which is implicated with a role in male fertility and is a candidate for the azoospermia factor gene. We have identified a new member of this gene family, HNRNP G-T, and have mapped it as a single-copy gene on chromosome 11. This gene contains an uninterrupted open reading frame and no introns, consistent with derivation from a retroposon. However, unlike many retroposon-derived genes, HNRNP G-T is not a pseudogene. An antiserum raised to the conceptual reading frame of HNRNP G-T showed that it encodes a protein that is highly expressed in germ cells and in particular in the nuclei of meiotic spermatocytes. Surprisingly, although this antiserum was raised against human hnRNP G-T protein, it can also detect a similar protein in the testis of several mammals. This suggests that the protein is highly conserved and that the retrotransposition event generating the HNRNP G-T gene pre-dated at least the common ancestor of mouse and man. The existence of an additional testis-specific hnRNP G family member provides evidence for the importance of these proteins in normal germ cell development.
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Affiliation(s)
- D J Elliott
- MRC Human Genetics Unit, Western General Hospital, Crewe Road, Edinburgh EH4 2XU, UK.
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26
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Venables JP, Elliott DJ, Makarova OV, Makarov EM, Cooke HJ, Eperon IC. RBMY, a probable human spermatogenesis factor, and other hnRNP G proteins interact with Tra2beta and affect splicing. Hum Mol Genet 2000; 9:685-94. [PMID: 10749975 DOI: 10.1093/hmg/9.5.685] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The RBMY gene family is found on the Y chromosome of all mammals, and microdeletions are strongly associated with infertility in men. RBMY expresses RBM only in the nuclei of germ cells, whereas its X chromosome homologue, RBMX, expresses hnRNP G ubiquitously. We show here that RBM, hnRNP G and a novel testis-specific relative, termed hnRNP G-T, interact with Tra2beta, an activator of pre-mRNA splicing that is ubiquitous but highly expressed in testis. Endogenous hnRNP G and Tra2beta proteins are associated in HeLa nuclear extracts. RBM and Tra2beta co-localize in two major domains in human spermatocyte nuclei. Phosphorylation enhanced the interaction and reduced competing RNA binding to the interaction domains. Incubation with the protein interaction domain of RBM inhibited splicing in vitro of a specific pre-mRNA substrate containing an essential enhancer bound by Tra2beta. The RNA-binding domain of RBM affected 5' splice site selection. We conclude that the hnRNP G family of proteins is involved in pre-mRNA splicing and infer that RBM may be involved in Tra2beta-dependent splicing in spermatocytes.
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Affiliation(s)
- J P Venables
- Department of Biochemistry, University of Leicester, University Road, Leicester LE1 7RH, UK
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27
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Abstract
RNA-binding proteins are essential for spermatogenesis: they are required in the nucleus of germ cells, for the production of specific mRNA isoforms, and in the cytoplasm - where proteins required for chromatin condensation and for changes in cell morphology are translated long after transcription ceases. Some of the RNA targets and the RNA-binding proteins themselves have been identified recently. Both nuclear and cytoplasmic proteins are affected in examples of azoospermia in men.
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Affiliation(s)
- J P Venables
- Department of Biochemistry University of Leicester University Road, Leicester, LE1 7RH, UK.
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28
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Venables JP, Vernet C, Chew SL, Elliott DJ, Cowmeadow RB, Wu J, Cooke HJ, Artzt K, Eperon IC. T-STAR/ETOILE: a novel relative of SAM68 that interacts with an RNA-binding protein implicated in spermatogenesis. Hum Mol Genet 1999; 8:959-69. [PMID: 10332027 DOI: 10.1093/hmg/8.6.959] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
RBM is an RNA-binding protein encoded on the Y chromosome in mammals and is expressed only in the nuclei of male germ cells. Genetic evidence from infertile men implicates it in spermatogenesis, but its function is unknown. Of a number of potential partners for RBM identified by a yeast two-hybrid screen with testis cDNA, the most frequent isolates encoded a novel RNA-binding protein, termed T-STAR, that is closely related to SAM68, an Src-associated protein of unknown function. The mouse homologue was also cloned and designated étoile. It mapped to chromosome 15, while T-STAR mapped to the syntenic region on human chromosome 8. T-STAR/étoile is expressed primarily in the testis; in rat germ cells, the expression of both T-STAR/étoile and SAM68 is regulated during meiosis. Transfection of T-STAR/étoile fused with green fluorescent protein into HeLa cells caused an accumulation of protein in a novel compartment of the nucleus, adjacent to the nucleolus but distinct from the peri-nucleolar compartment. RBM and other hnRNP G family members are candidate downstream targets for regulation by T-STAR/ETOILE and SAM68.
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MESH Headings
- 3T3 Cells
- Adaptor Proteins, Signal Transducing
- Amino Acid Sequence
- Animals
- Blotting, Northern
- COS Cells
- Cell Nucleus/chemistry
- Chromosome Mapping
- Chromosomes, Human, Pair 8/genetics
- DNA, Complementary/chemistry
- DNA, Complementary/genetics
- DNA-Binding Proteins
- Gene Expression
- HeLa Cells
- Humans
- Male
- Mice
- Mice, Inbred C57BL
- Molecular Sequence Data
- Muridae
- Plasmids
- Protein Binding
- RNA/metabolism
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA-Binding Proteins/genetics
- RNA-Binding Proteins/metabolism
- Rats
- Saccharomyces cerevisiae/genetics
- Sequence Alignment
- Sequence Homology, Amino Acid
- Spermatogenesis
- Tissue Distribution
- Tumor Suppressor Protein p53/genetics
- Tumor Suppressor Protein p53/metabolism
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Affiliation(s)
- J P Venables
- Department of Biochemistry, University of Leicester, UK
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