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Erdmann EA, Forbes M, Becker M, Perez S, Hundley HA. ADR-2 regulates fertility and oocyte fate in C. elegans. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.11.01.565157. [PMID: 37961348 PMCID: PMC10635048 DOI: 10.1101/2023.11.01.565157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
RNA binding proteins play essential roles in coordinating germline gene expression and development in all organisms. Here, we report that loss of ADR-2, a member of the Adenosine DeAminase acting on RNA (ADAR) family of RNA binding proteins and the sole adenosine-to-inosine RNA editing enzyme in C. elegans, can improve fertility in multiple genetic backgrounds. First, we show that loss of RNA editing by ADR-2 restores normal embryo production to subfertile animals that transgenically express a vitellogenin (yolk protein) fusion to green fluorescent protein. Using this phenotype, a high-throughput screen was designed to identify RNA binding proteins that when depleted yield synthetic phenotypes with loss of adr-2. The screen uncovered a genetic interaction between ADR-2 and SQD-1, a member of the heterogenous nuclear ribonucleoprotein (hnRNP) family of RNA binding proteins. Microscopy, reproductive assays, and high-throughput sequencing reveal that sqd-1 is essential for the onset of oogenesis and oogenic gene expression in young adult animals, and that loss of adr-2 can counteract the effects of loss of sqd-1 on gene expression and rescue the switch from spermatogenesis to oogenesis. Together, these data demonstrate that ADR-2 can contribute to the suppression of fertility and suggest novel roles for both RNA editing-dependent and independent mechanisms in regulating embryogenesis.
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Affiliation(s)
- Emily A. Erdmann
- Genome, Cell and Developmental Biology Graduate Program, Indiana University, Bloomington IN, US 47405
| | - Melanie Forbes
- Department of Biology, Indiana University, Bloomington IN, US 47405
| | - Margaret Becker
- Medical Sciences Program, Indiana University School of Medicine-Bloomington, Bloomington IN, US 47405
| | - Sarina Perez
- Department of Biology, Indiana University, Bloomington IN, US 47405
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2
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Cassani M, Seydoux G. Specialized germline P-bodies are required to specify germ cell fate in Caenorhabditis elegans embryos. Development 2022; 149:dev200920. [PMID: 36196602 PMCID: PMC9686995 DOI: 10.1242/dev.200920] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Accepted: 09/06/2022] [Indexed: 07/30/2023]
Abstract
In animals with germ plasm, specification of the germline involves 'germ granules', cytoplasmic condensates that enrich maternal transcripts in the germline founder cells. In Caenorhabditis elegans embryos, P granules enrich maternal transcripts, but surprisingly P granules are not essential for germ cell fate specification. Here, we describe a second condensate in the C. elegans germ plasm. Like canonical P-bodies found in somatic cells, 'germline P-bodies' contain regulators of mRNA decapping and deadenylation and, in addition, the intrinsically-disordered proteins MEG-1 and MEG-2 and the TIS11-family RNA-binding protein POS-1. Embryos lacking meg-1 and meg-2 do not stabilize P-body components, misregulate POS-1 targets, mis-specify the germline founder cell and do not develop a germline. Our findings suggest that specification of the germ line involves at least two distinct condensates that independently enrich and regulate maternal mRNAs in the germline founder cells. This article has an associated 'The people behind the papers' interview.
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Affiliation(s)
- Madeline Cassani
- Howard Hughes Medical Institute and Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Geraldine Seydoux
- Howard Hughes Medical Institute and Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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3
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Marín JD, Vargas S, Ruiz-Ordoñez I, Posso-Osorio I, Nieto-Aristizábal I, Barrera MC, Ríos-Serna LJ, Tobón GJ. Association of Antiribosomal P Antibody with Neurological and Systemic Manifestations in Patients with Systemic Lupus Erythematosus in Southwestern Colombia. J Appl Lab Med 2021; 7:3-11. [PMID: 34086896 DOI: 10.1093/jalm/jfab045] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 03/22/2021] [Indexed: 11/13/2022]
Abstract
BACKGROUND Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by heterogeneous pathogenesis, various clinical manifestations, and a broad spectrum of autoantibodies which recognize different cellular components. This study examines the clinical significance and serological associations of serum antiribosomal P antibodies (anti-P) derived from SLE patients in a population from southwestern Colombia. METHODS We performed a cross-sectional study of 66 SLE patients. Serum antiribosomal P0 autoantibodies were detected by line immunoassay using the ANA-LIA MAXX kit and processed on the automated HumaBlot 44FA system (Human Diagnostics, Germany). RESULTS Of the 66 SLE patients included in the study, 17 patients (25.76%) showed anti-P positivity by line immunoassay (IA), 47 (71.21%) were negative, and results from 2 patients were indeterminate. We did not find an association with neuropsychiatric SLE (NPSLE), renal, or hepatic disorders (P > 0.05). Laboratory findings indicated that anti-P positivity was significantly associated to anti-Smith (P = 0.001), anti-Ro60/SSA (P = 0.046), and anti-dsDNA antibodies (P = 0.034), the latter being true only when performed using indirect immunofluorescence (IIF). CONCLUSION The anti-P antibodies are not associated with clinical manifestations such as NPSLE, lupus nephritis, or hepatic involvement in the southwest Colombian SLE population. Moreover, we confirmed previously reported association between anti-P antibody, serum anti-dsDNA, and anti-Smith.
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Affiliation(s)
| | | | - Ingrid Ruiz-Ordoñez
- Fundación Valle del Lili, Centro de Investigaciones Clínicas, Cali, Colombia
| | - Iván Posso-Osorio
- Fundación Valle del Lili, Centro de Investigaciones Clínicas, Cali, Colombia
| | | | - María Claudia Barrera
- Universidad Icesi, CIRAT: Centro de Investigación en Reumatología, Autoinmunidad y Medicina Traslacional, Universidad Icesi, Cali, Colombia
| | - Lady J Ríos-Serna
- Universidad Icesi, CIRAT: Centro de Investigación en Reumatología, Autoinmunidad y Medicina Traslacional, Universidad Icesi, Cali, Colombia
| | - Gabriel J Tobón
- Universidad Icesi, CIRAT: Centro de Investigación en Reumatología, Autoinmunidad y Medicina Traslacional, Universidad Icesi, Cali, Colombia.,Fundación Valle del Lili, Unit of Rheumatology, Cali, Colombia
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4
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Sundby AE, Molnar RI, Claycomb JM. Connecting the Dots: Linking Caenorhabditis elegans Small RNA Pathways and Germ Granules. Trends Cell Biol 2021; 31:387-401. [PMID: 33526340 DOI: 10.1016/j.tcb.2020.12.012] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 12/28/2020] [Accepted: 12/30/2020] [Indexed: 12/15/2022]
Abstract
Germ granules are non-membrane bound, phase-separated organelles, composed of RNAs and proteins. Germ granules are present only within the germ cells of animals, including model systems such as Caenorhabditis elegans, Drosophila, mice, and zebrafish, where they play critical roles in specifying the germ lineage, the inheritance of epigenetic information, and post-transcriptional gene regulation. Across species, conserved germ granule proteins reflect these essential functions. A significant proportion of proteins that localize to germ granules are components of RNA metabolism and small RNA (sRNA) gene regulatory pathways. Here we synthesize our current knowledge of the roles that germ granules and their components play in sRNA pathway functions, transgenerational inheritance, and fertility in the C. elegans germline.
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Affiliation(s)
- Adam E Sundby
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Ruxandra I Molnar
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Julie M Claycomb
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada.
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5
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Hyjek‐Składanowska M, Bajczyk M, Gołębiewski M, Nuc P, Kołowerzo‐Lubnau A, Jarmołowski A, Smoliński DJ. Core spliceosomal Sm proteins as constituents of cytoplasmic mRNPs in plants. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 103:1155-1173. [PMID: 32369637 PMCID: PMC7540296 DOI: 10.1111/tpj.14792] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 04/13/2020] [Accepted: 04/21/2020] [Indexed: 05/15/2023]
Abstract
In recent years, research has increasingly focused on the key role of post-transcriptional regulation of messenger ribonucleoprotein (mRNP) function and turnover. As a result of the complexity and dynamic nature of mRNPs, the full composition of a single mRNP complex remains unrevealed and mRNPs are poorly described in plants. Here we identify canonical Sm proteins as part of the cytoplasmic mRNP complex, indicating their function in the post-transcriptional regulation of gene expression in plants. Sm proteins comprise an evolutionarily ancient family of small RNA-binding proteins involved in pre-mRNA splicing. The latest research indicates that Sm could also impact on mRNA at subsequent stages of its life cycle. In this work we show that in the microsporocyte cytoplasm of Larix decidua, the European larch, Sm proteins accumulate within distinct cytoplasmic bodies, also containing polyadenylated RNA. To date, several types of cytoplasmic bodies involved in the post-transcriptional regulation of gene expression have been described, mainly in animal cells. Their role and molecular composition in plants remain less well established, however. A total of 222 mRNA transcripts have been identified as cytoplasmic partners for Sm proteins. The specific colocalization of these mRNAs with Sm proteins within cytoplasmic bodies has been confirmed via microscopic analysis. The results from this work support the hypothesis, that evolutionarily conserved Sm proteins have been adapted to perform a whole repertoire of functions related to the post-transcriptional regulation of gene expression in Eukaryota. This adaptation presumably enabled them to coordinate the interdependent processes of splicing element assembly, mRNA maturation and processing, and mRNA translation regulation, and its degradation.
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Affiliation(s)
- Malwina Hyjek‐Składanowska
- Department of Cellular and Molecular BiologyNicolaus Copernicus UniveristyLwowska 187‐100TorunPoland
- Centre For Modern Interdisciplinary TechnologiesNicolaus Copernicus UniversityWilenska 487‐100TorunPoland
- Present address:
Laboratory of Protein StructureInternational Institute of Molecular and Cell Biology4 Trojdena St.02‐109WarsawPoland
| | - Mateusz Bajczyk
- Department of Gene ExpressionInstitute of Molecular Biology and BiotechnologyAdam Mickiewicz UniversityUmultowska 89Poznan61‐614Poland
| | - Marcin Gołębiewski
- Centre For Modern Interdisciplinary TechnologiesNicolaus Copernicus UniversityWilenska 487‐100TorunPoland
- Department of Plant Physiology and BiotechnologyNicolaus Copernicus UniveristyLwowska 187‐100TorunPoland
| | - Przemysław Nuc
- Department of Gene ExpressionInstitute of Molecular Biology and BiotechnologyAdam Mickiewicz UniversityUmultowska 89Poznan61‐614Poland
| | - Agnieszka Kołowerzo‐Lubnau
- Department of Cellular and Molecular BiologyNicolaus Copernicus UniveristyLwowska 187‐100TorunPoland
- Centre For Modern Interdisciplinary TechnologiesNicolaus Copernicus UniversityWilenska 487‐100TorunPoland
| | - Artur Jarmołowski
- Department of Gene ExpressionInstitute of Molecular Biology and BiotechnologyAdam Mickiewicz UniversityUmultowska 89Poznan61‐614Poland
| | - Dariusz Jan Smoliński
- Department of Cellular and Molecular BiologyNicolaus Copernicus UniveristyLwowska 187‐100TorunPoland
- Centre For Modern Interdisciplinary TechnologiesNicolaus Copernicus UniversityWilenska 487‐100TorunPoland
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6
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Hubstenberger A, Noble SL, Cameron C, Evans TC. Translation repressors, an RNA helicase, and developmental cues control RNP phase transitions during early development. Dev Cell 2014; 27:161-173. [PMID: 24176641 DOI: 10.1016/j.devcel.2013.09.024] [Citation(s) in RCA: 135] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Revised: 08/27/2013] [Accepted: 09/26/2013] [Indexed: 12/27/2022]
Abstract
Like membranous organelles, large-scale coassembly of macromolecules can organize functions in cells. Ribonucleoproteins (RNPs) can form liquid or solid aggregates, but control and consequences of these RNP states in living, developing tissue are poorly understood. Here, we show that regulated RNP factor interactions drive transitions among diffuse, semiliquid, or solid states to modulate RNP sorting and exchange in the Caenorhabditis elegans oocyte cytoplasm. Translation repressors induce an intrinsic capacity of RNP components to coassemble into either large semiliquids or solid lattices, whereas a conserved RNA helicase prevents polymerization into nondynamic solids. Developmental cues dramatically alter both fluidity and sorting within large RNP assemblies, inducing a transition from RNP segregation in quiescent oocytes to dynamic exchange in the early embryo. Therefore, large-scale organization of gene expression extends to the cytoplasm, where regulation of supramolecular states imparts specific patterns of RNP dynamics.
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Affiliation(s)
- Arnaud Hubstenberger
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Scott L Noble
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA; Graduate Program in Molecular Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Cristiana Cameron
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Thomas C Evans
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA.
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7
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Lu Z, Guan X, Schmidt CA, Matera AG. RIP-seq analysis of eukaryotic Sm proteins identifies three major categories of Sm-containing ribonucleoproteins. Genome Biol 2014; 15:R7. [PMID: 24393626 PMCID: PMC4053861 DOI: 10.1186/gb-2014-15-1-r7] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Accepted: 01/07/2014] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Sm proteins are multimeric RNA-binding factors, found in all three domains of life. Eukaryotic Sm proteins, together with their associated RNAs, form small ribonucleoprotein (RNP) complexes important in multiple aspects of gene regulation. Comprehensive knowledge of the RNA components of Sm RNPs is critical for understanding their functions. RESULTS We developed a multi-targeting RNA-immunoprecipitation sequencing (RIP-seq) strategy to reliably identify Sm-associated RNAs from Drosophila ovaries and cultured human cells. Using this method, we discovered three major categories of Sm-associated transcripts: small nuclear (sn)RNAs, small Cajal body (sca)RNAs and mRNAs. Additional RIP-PCR analysis showed both ubiquitous and tissue-specific interactions. We provide evidence that the mRNA-Sm interactions are mediated by snRNPs, and that one of the mechanisms of interaction is via base pairing. Moreover, the Sm-associated mRNAs are mature, indicating a splicing-independent function for Sm RNPs. CONCLUSIONS This study represents the first comprehensive analysis of eukaryotic Sm-containing RNPs, and provides a basis for additional functional analyses of Sm proteins and their associated snRNPs outside of the context of pre-mRNA splicing. Our findings expand the repertoire of eukaryotic Sm-containing RNPs and suggest new functions for snRNPs in mRNA metabolism.
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Affiliation(s)
- Zhipeng Lu
- Departments of Biology and Genetics, Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC 27599-3280, USA
| | - Xiaojun Guan
- Center for Bioinformatics, University of North Carolina, Chapel Hill, NC 27599-3280, USA
- Current address: Sequenom, San Diego, CA 92121, USA
| | - Casey A Schmidt
- Curriculum in Genetics & Molecular Biology, University of North Carolina, Chapel Hill, NC 27599-3280, USA
| | - A Gregory Matera
- Departments of Biology and Genetics, Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC 27599-3280, USA
- Curriculum in Genetics & Molecular Biology, University of North Carolina, Chapel Hill, NC 27599-3280, USA
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8
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Seervai RNH, Wessel GM. Lessons for inductive germline determination. Mol Reprod Dev 2013; 80:590-609. [PMID: 23450642 DOI: 10.1002/mrd.22151] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Accepted: 01/03/2013] [Indexed: 12/25/2022]
Abstract
Formation of the germline in an embryo marks a fresh round of reproductive potential, yet the developmental stage and location within the embryo where the primordial germ cells (PGCs) form differs wildly among species. In most animals, the germline is formed either by an inherited mechanism, in which maternal provisions within the oocyte drive localized germ-cell fate once acquired in the embryo, or an inductive mechanism that involves signaling between cells that directs germ-cell fate. The inherited mechanism has been widely studied in model organisms such as Drosophila melanogaster, Caenorhabditis elegans, Xenopus laevis, and Danio rerio. Given the rapid generation time and the effective adaptation for laboratory research of these organisms, it is not coincidental that research on these organisms has led the field in elucidating mechanisms for germline specification. The inductive mechanism, however, is less well understood and is studied primarily in the mouse (Mus musculus). In this review, we compare and contrast these two fundamental mechanisms for germline determination, beginning with the key molecular determinants that play a role in the formation of germ cells across all animal taxa. We next explore the current understanding of the inductive mechanism of germ-cell determination in mice, and evaluate the hypotheses for selective pressures on these contrasting mechanisms. We then discuss the hypothesis that the transition between these determination mechanisms, which has happened many times in phylogeny, is more of a continuum than a binary change. Finally, we propose an analogy between germline determination and sex determination in vertebrates-two of the milestones of reproduction and development-in which animals use contrasting strategies to activate similar pathways.
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Affiliation(s)
- Riyad N H Seervai
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, Rhode Island, 02192, USA
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9
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Wang JT, Seydoux G. Germ cell specification. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 757:17-39. [PMID: 22872473 DOI: 10.1007/978-1-4614-4015-4_2] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The germline of Caenorhabditis elegans derives from a single founder cell, the germline blastomere P(4). P(4) is the product of four asymmetric cleavages that divide the zygote into distinct somatic and germline (P) lineages. P(4) inherits a specialized cytoplasm ("germ plasm") containing maternally encoded proteins and RNAs. The germ plasm has been hypothesized to specify germ cell fate, but the mechanisms involved remain unclear. Three processes stand out: (1) inhibition of mRNA transcription to prevent activation of somatic development, (2) translational regulation of the nanos homolog nos-2 and of other germ plasm mRNAs, and (3) establishment of a unique, partially repressive chromatin. Together, these processes ensure that the daughters of P(4), the primordial germ cells Z2 and Z3, gastrulate inside the embryo, associate with the somatic gonad, initiate the germline transcriptional program, and proliferate during larval development to generate ∼2,000 germ cells by adulthood.
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Affiliation(s)
- Jennifer T Wang
- Department of Molecular Biology and Genetics, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
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10
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Abstract
The germ line represents a continuous cellular link between generations and between species, but the germ cells themselves develop in a specialized, organism-specific context. The model organisms Caenorhabditis elegans, Drosophila melanogaster and the mouse display striking similarities, as well as major differences, in the means by which they control germ cell development. Recent developments in genetic technologies allow a more detailed comparison of the germ cells of these three organisms than has previously been possible, shedding light not only on universal aspects of germline regulation, but also on the control of the pluripotent state in vivo and on the earliest steps of embryogenesis. Here, we highlight themes from the comparison of these three alternative strategies for navigating the fundamental cycle of sexual reproduction.
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11
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Hubstenberger A, Cameron C, Shtofman R, Gutman S, Evans TC. A network of PUF proteins and Ras signaling promote mRNA repression and oogenesis in C. elegans. Dev Biol 2012; 366:218-31. [PMID: 22542599 PMCID: PMC3361503 DOI: 10.1016/j.ydbio.2012.03.019] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Revised: 02/21/2012] [Accepted: 03/19/2012] [Indexed: 11/16/2022]
Abstract
Cell differentiation requires integration of gene expression controls with dynamic changes in cell morphology, function, and control. Post-transcriptional mRNA regulation and signaling systems are important to this process but their mechanisms and connections are unclear. During C. elegans oogenesis, we find that two groups of PUF RNA binding proteins (RNABPs), PUF-3/11 and PUF-5/6/7, control different specific aspects of oocyte formation. PUF-3/11 limits oocyte growth, while PUF-5/6/7 promotes oocyte organization and formation. These two PUF groups repress mRNA translation through overlapping but distinct sets of 3' untranslated regions (3'UTRs). Several PUF-dependent mRNAs encode other mRNA regulators suggesting both PUF groups control developmental patterning of mRNA regulation circuits. Furthermore, we find that the Ras-MapKinase/ERK pathway functions with PUF-5/6/7 to repress specific mRNAs and control oocyte organization and growth. These results suggest that diversification of PUF proteins and their integration with Ras-MAPK signaling modulates oocyte differentiation. Together with other studies, these findings suggest positive and negative interactions between the Ras-MAPK system and PUF RNA-binding proteins likely occur at multiple levels. Changes in these interactions over time can influence spatiotemporal patterning of tissue development.
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Affiliation(s)
- Arnaud Hubstenberger
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora CO 80045
| | - Cristiana Cameron
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora CO 80045
| | - Rebecca Shtofman
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora CO 80045
| | - Shiri Gutman
- Program in Cell biology, Stem Cells, and Development, University of Colorado Anschutz Medical Campus, Aurora CO 80045
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora CO 80045
| | - Thomas C. Evans
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora CO 80045
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Joseph-Strauss D, Gorjánácz M, Santarella-Mellwig R, Voronina E, Audhya A, Cohen-Fix O. Sm protein down-regulation leads to defects in nuclear pore complex disassembly and distribution in C. elegans embryos. Dev Biol 2012; 365:445-57. [PMID: 22426005 DOI: 10.1016/j.ydbio.2012.02.036] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Revised: 01/24/2012] [Accepted: 02/29/2012] [Indexed: 10/28/2022]
Abstract
Nuclear pore complexes (NPCs) are large macromolecular structures embedded in the nuclear envelope (NE), where they facilitate exchange of molecules between the cytoplasm and the nucleoplasm. In most cell types, NPCs are evenly distributed around the NE. However, the mechanisms dictating NPC distribution are largely unknown. Here, we used the model organism Caenorhabditis elegans to identify genes that affect NPC distribution during early embryonic divisions. We found that down-regulation of the Sm proteins, which are core components of the spliceosome, but not down-regulation of other splicing factors, led to clustering of NPCs. Down-regulation of Sm proteins also led to incomplete disassembly of NPCs during mitosis, but had no effect on lamina disassembly, suggesting that the defect in NPC disassembly was not due to a general defect in nuclear envelope breakdown. We further found that these mitotic NPC remnants persisted on an ER membrane that juxtaposes the mitotic spindle. At the end of mitosis, the remnant NPCs moved toward the chromatin and the reforming NE, where they ultimately clustered by forming membrane stacks perforated by NPCs. Our results suggest a novel, splicing-independent, role for Sm proteins in NPC disassembly, and point to a possible link between NPC disassembly in mitosis and NPC distribution in the subsequent interphase.
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Affiliation(s)
- Daphna Joseph-Strauss
- The Laboratory of Molecular and Cellular Biology, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, 8 Center Drive, Bethesda MD 20892, USA
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13
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Anchi T, Tamura K, Furihata M, Satake H, Sakoda H, Kawada C, Kamei M, Shimamoto T, Fukuhara H, Fukata S, Ashida S, Karashima T, Yamasaki I, Yasuda M, Kamada M, Inoue K, Shuin T. SNRPE is involved in cell proliferation and progression of high-grade prostate cancer through the regulation of androgen receptor expression. Oncol Lett 2011; 3:264-268. [PMID: 22740892 DOI: 10.3892/ol.2011.505] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2011] [Accepted: 11/18/2011] [Indexed: 11/05/2022] Open
Abstract
Clinically high-grade prostate cancers (PC) with high Gleason scores of 8-10 exhibit rapid growth and are more likely to spread beyond the prostate. These cancer types demonstrate a poor response to androgen deprivation therapy and eventually acquire a castration-resistant phenotype. To identify novel molecular cancer drug targets, we previously analyzed the gene expression profiles of high-grade PC using a cDNA microarray combined with laser microbeam microdissection and found a number of genes that are transactivated in high-grade PC. Among these genes, we report the identification of a novel molecular target, small nuclear ribonucleoprotein polypeptide E (SNRPE). Semi-quantitative RT-PCR confirmed that SNRPE is overexpressed in high-grade PC cells compared with normal prostatic epithelial cells. Knockdown of SNRPE expression by short interfering RNA (siRNA) resulted in the marked suppression of PC cell proliferation. By contrast, SNRPE overexpression promoted PC cell proliferation, indicating its oncogenic effects. Furthermore, we demonstrated that SNRPE regulates androgen receptor (AR) mRNA expression in PC cells. Knockdown of SNRPE expression by siRNA resulted in the marked suppression of AR and its downstream target genes at the mRNA level. We suggest that the regulation of AR expression by SNRPE is essential for cell proliferation and progression of high-grade PC and that it may be a novel molecular target for cancer drugs.
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Affiliation(s)
- Takashi Anchi
- Department of Urology, Kochi Medical School, Kochi University, Nankoku, Kochi 783-8505
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14
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Periodic expression of Sm proteins parallels formation of nuclear Cajal bodies and cytoplasmic snRNP-rich bodies. Histochem Cell Biol 2011; 136:527-41. [PMID: 21904826 PMCID: PMC3192945 DOI: 10.1007/s00418-011-0861-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/24/2011] [Indexed: 11/26/2022]
Abstract
Small nuclear ribonucleoproteins (snRNPs) play a fundamental role in pre-mRNA processing in the nucleus. The biogenesis of snRNPs involves a sequence of events that occurs in both the nucleus and cytoplasm. Despite the wealth of biochemical information about the cytoplasmic assembly of snRNPs, little is known about the spatial organization of snRNPs in the cytoplasm. In the cytoplasm of larch microsporocytes, a cyclic appearance of bodies containing small nuclear RNA (snRNA) and Sm proteins was observed during anther meiosis. We observed a correlation between the occurrence of cytoplasmic snRNP bodies, the levels of Sm proteins, and the dynamic formation of Cajal bodies. Larch microsporocytes were used for these studies. This model is characterized by natural fluctuations in the level of RNA metabolism, in which periods of high transcriptional activity are separated from periods of low transcriptional activity. In designing experiments, the authors considered the differences between the nuclear and cytoplasmic phases of snRNP maturation and generated a hypothesis about the direct participation of Sm proteins in a molecular switch triggering the formation of Cajal bodies.
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Swaraz AM, Park YD, Hur Y. Knock-out mutations of Arabidopsis SmD3-b induce pleotropic phenotypes through altered transcript splicing. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2011; 180:661-671. [PMID: 21421416 DOI: 10.1016/j.plantsci.2011.01.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Revised: 01/13/2011] [Accepted: 01/19/2011] [Indexed: 05/30/2023]
Abstract
SmD3 is a core protein of small nuclear ribonucleoprotein (snRNP) essential for splicing of primary transcripts. To elucidate function of SmD3 protein in plants, phenotypes and gene expression of SmD3 knock-out and overexpressing mutants in Arabidopsis have been analyzed. smd3-a knock-out mutant or SmD3-a and SmD3-b overexpressors did not show phenotypic alteration. Knock-out of SmD3-b resulted in the pleotropic phenotypes of delayed flowering time and completion of life cycle, reduced root growth, partially defective leaf venation, abnormal numbers of trichome branches, and changed numbers of floral organs. Microarray data revealed that the smd3-b mutant had altered expression of genes related to the above phenotypes, indirectly suggesting that changed splicing of these genes may cause the observed phenotypes. Splicing of selected genes was either totally blocked or reduced in the smd3-b mutant, indicating the important role of SmD3-b in the process. A double knock-out mutant of smd3-a and smd3-b could not be generated, indicating possible redundant function of these two genes. All data indicate that SmD3-b may be major component of the spliceosomal snRNP in Arabidopsis, but the function of SmD3-a may be redundant.
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Affiliation(s)
- A M Swaraz
- Department of Biological Sciences, Chungnam National University, Daejeon 305-764, Republic of Korea
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16
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Gonsalvez GB, Rajendra TK, Wen Y, Praveen K, Matera AG. Sm proteins specify germ cell fate by facilitating oskar mRNA localization. Development 2010; 137:2341-51. [PMID: 20570937 DOI: 10.1242/dev.042721] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Sm and Sm-like proteins are RNA-binding factors found in all three domains of life. Eukaryotic Sm proteins play essential roles in pre-mRNA splicing, forming the cores of spliceosomal small nuclear ribonucleoproteins (snRNPs). Recently, Sm proteins have been implicated in the specification of germ cells. However, a mechanistic understanding of their involvement in germline specification is lacking and a germline-specific RNA target has not been identified. We demonstrate that Drosophila SmB and SmD3 are specific components of the oskar messenger ribonucleoprotein (mRNP), proper localization of which is required for establishing germline fate and embryonic patterning. Importantly, oskar mRNA is delocalized in females harboring a hypomorphic mutation in SmD3, and embryos from mutant mothers are defective in germline specification. We conclude that Sm proteins function to establish the germline in Drosophila, at least in part by mediating oskar mRNA localization.
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Affiliation(s)
- Graydon B Gonsalvez
- Departments of Biology and Genetics, Program in Molecular Biology and Biotechnology, University of North Carolina, Chapel Hill, NC 27599-3280, USA.
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Ewen-Campen B, Schwager EE, Extavour CGM. The molecular machinery of germ line specification. Mol Reprod Dev 2010; 77:3-18. [PMID: 19790240 DOI: 10.1002/mrd.21091] [Citation(s) in RCA: 129] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Germ cells occupy a unique position in animal reproduction, development, and evolution. In sexually reproducing animals, only they can produce gametes and contribute genetically to subsequent generations. Nonetheless, germ line specification during embryogenesis is conceptually the same as the specification of any somatic cell type: germ cells must activate a specific gene regulatory network in order to differentiate and go through gametogenesis. While many genes with critical roles in the germ line have been characterized with respect to expression pattern and genetic interactions, it is the molecular interactions of the relevant gene products that are ultimately responsible for germ cell differentiation. This review summarizes the current state of knowledge on the molecular functions and biochemical connections between germ line gene products. We find that homologous genes often interact physically with the same conserved molecular partners across the metazoans. We also point out cases of nonhomologous genes from different species whose gene products play analogous biological roles in the germ line. We suggest a preliminary molecular definition of an ancestral "pluripotency module" that could have been modified during metazoan evolution to become specific to the germ line.
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Affiliation(s)
- Ben Ewen-Campen
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, USA
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18
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A genomewide RNAi screen for genes that affect the stability, distribution and function of P granules in Caenorhabditis elegans. Genetics 2009; 183:1397-419. [PMID: 19805813 DOI: 10.1534/genetics.109.110171] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
P granules are non-membrane-bound organelles found in the germ-line cytoplasm throughout Caenorhabditis elegans development. Like their "germ granule" counterparts in other animals, P granules are thought to act as determinants of the identity and special properties of germ cells, properties that include the unique ability to give rise to all tissues of future generations of an organism. Therefore, understanding how P granules work is critical to understanding how cellular immortality and totipotency are retained, gained, and lost. Here we report on a genomewide RNAi screen in C. elegans, which identified 173 genes that affect the stability, localization, and function of P granules. Many of these genes fall into specific classes with shared P-granule phenotypes, allowing us to better understand how cellular processes such as protein degradation, translation, splicing, nuclear transport, and mRNA homeostasis converge on P-granule assembly and function. One of the more striking phenotypes is caused by the depletion of CSR-1, an Argonaute associated with an endogenous siRNA pathway that functions in the germ line. We show that CSR-1 and two other endo-siRNA pathway members, the RNA-dependent RNA polymerase EGO-1 and the helicase DRH-3, act to antagonize RNA and P-granule accumulation in the germ line. Our findings strengthen the emerging view that germ granules are involved in numerous aspects of RNA metabolism, including an endo-siRNA pathway in germ cells.
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Noble SL, Allen BL, Goh LK, Nordick K, Evans TC. Maternal mRNAs are regulated by diverse P body-related mRNP granules during early Caenorhabditis elegans development. J Cell Biol 2008; 182:559-72. [PMID: 18695046 PMCID: PMC2500140 DOI: 10.1083/jcb.200802128] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2008] [Accepted: 07/08/2008] [Indexed: 01/15/2023] Open
Abstract
Processing bodies (P bodies) are conserved mRNA-protein (mRNP) granules that are thought to be cytoplasmic centers for mRNA repression and degradation. However, their specific functions in vivo remain poorly understood. We find that repressed maternal mRNAs and their regulators localize to P body-like mRNP granules in the Caenorhabditis elegans germ line. Surprisingly, several distinct types of regulated granules form during oocyte and embryo development. 3' untranslated region elements direct mRNA targeting to one of these granule classes. The P body factor CAR-1/Rap55 promotes association of repressed mRNA with granules and contributes to repression of Notch/glp-1 mRNA. However, CAR-1 controls Notch/glp-1 only during late oogenesis, where it functions with the RNA-binding regulators PUF-5, PUF-6, and PUF-7. The P body protein CGH-1/Rck/Dhh1 differs from CAR-1 in control of granule morphology and promotes mRNP stability in arrested oocytes. Therefore, a system of diverse and regulated RNP granules elicits stage-specific functions that ensure proper mRNA control during early development.
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Affiliation(s)
- Scott L Noble
- Program in Molecular Biology, University of Colorado, Denver Health Sciences Center, Aurora, CO 80045, USA
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20
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Li Z, Pützer BM. Spliceosomal protein E regulates neoplastic cell growth by modulating expression of cyclin E/CDK2 and G2/M checkpoint proteins. J Cell Mol Med 2008; 12:2427-38. [PMID: 18208561 PMCID: PMC4514120 DOI: 10.1111/j.1582-4934.2008.00244.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Small nuclear ribonucleoproteins are essential splicing factors. We previously identified the spliceosomal protein E (SmE) as a downstream effector of E2F1 in p53-deficient human carcinoma cells. Here, we investigated the biological relevance of SmE in determining the fate of cancer and non-tumourigenic cells. Adenovirus-mediated expression of SmE selectively reduces growth of cancerous cells due to decreased cell proliferation but not apoptosis. A similar growth inhibitory effect for SmD1 suggests that this is a general function of Sm-family members. Deletion of Sm-motifs reveals the importance of the Sm-1 domain for growth suppression. Consistently, SmE overexpression leads to inhibition of DNA synthesis and G2 arrest as shown by BrdU-incorporation and MPM2-staining. Real-time RT-PCR and immunoblotting showed that growth arrest by SmE directly correlates with the reduction of cyclin E, CDK2, CDC25C and CDC2 expression, and up-regulation of p27Kip. Importantly, SmE activity was not associated with enhanced expression of other spliceosome components such as U1 SnRNP70, suggesting that the growth inhibitory effect of SmE is distinct from its pre-mRNA splicing function. Furthermore, specific inactivation of SmE by shRNA significantly increased the percentage of cells in S phase, whereas the amount of G2/M arrested cells was reduced. Our data provide evidence that Sm proteins function as suppressors of tumour cell growth and may have major implications as cancer therapeutics.
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Affiliation(s)
- Z Li
- Department of Vectorology & Experimental Gene Therapy, Biomedical Research Center, University of Rostock, Germany
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21
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Abstract
Specification of germ cells in mice occurs relatively late in embryonic development. It is initiated by signals that induce expression of Blimp1, a key regulator of the germ cell, in a few epiblast cells of early postimplantation embryos. Blimp1 represses the incipient somatic program in these cells and promotes progression toward the germ cell fate. Blimp1 may also have a role in the maintenance of early germ cell characteristics by ensuring their escape from the somatic fate as well as possible reversion to pluripotent stem cells.
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Affiliation(s)
- Katsuhiko Hayashi
- Wellcome Trust Cancer Research UK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
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Ceron J, Rual JF, Chandra A, Dupuy D, Vidal M, van den Heuvel S. Large-scale RNAi screens identify novel genes that interact with the C. elegans retinoblastoma pathway as well as splicing-related components with synMuv B activity. BMC DEVELOPMENTAL BIOLOGY 2007; 7:30. [PMID: 17417969 PMCID: PMC1863419 DOI: 10.1186/1471-213x-7-30] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/25/2007] [Accepted: 04/06/2007] [Indexed: 11/10/2022]
Abstract
Background The retinoblastoma tumor suppressor (Rb) acts in a conserved pathway that is deregulated in most human cancers. Inactivation of the single Rb-related gene in Caenorhabditis elegans, lin-35, has only limited effects on viability and fertility, yet causes changes in cell-fate and cell-cycle regulation when combined with inactivation of specific other genes. For instance, lin-35 Rb is a synthetic multivulva (synMuv) class B gene, which causes a multivulva phenotype when inactivated simultaneously with a class A or C synMuv gene. Results We used the ORFeome RNAi library to identify genes that interact with C. elegans lin-35 Rb and identified 57 genes that showed synthetic or enhanced RNAi phenotypes in lin-35 mutants as compared to rrf-3 and eri-1 RNAi hypersensitive mutants. Based on characterizations of a deletion allele, the synthetic lin-35 interactor zfp-2 was found to suppress RNAi and to cooperate with lin-35 Rb in somatic gonad development. Interestingly, ten splicing-related genes were found to function similar to lin-35 Rb, as synMuv B genes that prevent inappropriate vulval induction. Partial inactivation of specific spliceosome components revealed further similarities with lin-35 Rb functions in cell-cycle control, transgene expression and restricted expression of germline granules. Conclusion We identified an extensive series of candidate lin-35 Rb interacting genes and validated zfp-2 as a novel lin-35 synthetic lethal gene. In addition, we observed a novel role for a subset of splicing components in lin-35 Rb-controlled processes. Our data support novel hypotheses about possibilities for anti-cancer therapies and multilevel regulation of gene expression.
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Affiliation(s)
- Julian Ceron
- Massachusetts General Hospital Cancer Center and Harvard Medical School, Building 149, 13th Street, Charlestown, 02129 MA, USA
- Present address : Molecular Oncology and Aging Research, Centre d'Investigacions en Bioquímica I Biología Molecular (CIBBIM), Hospital Universitari Vall d'Hebron 119-129, Barcelona 08035, Spain
| | - Jean-François Rual
- Center for Cancer Systems Biology (CCSB) and Department of Cancer Biology, Dana-Farber Cancer Institute, and Department of Genetics, Harvard Medical School, 44 Binney Street, Boston, 02115 MA, USA
| | - Abha Chandra
- Massachusetts General Hospital Cancer Center and Harvard Medical School, Building 149, 13th Street, Charlestown, 02129 MA, USA
| | - Denis Dupuy
- Center for Cancer Systems Biology (CCSB) and Department of Cancer Biology, Dana-Farber Cancer Institute, and Department of Genetics, Harvard Medical School, 44 Binney Street, Boston, 02115 MA, USA
| | - Marc Vidal
- Center for Cancer Systems Biology (CCSB) and Department of Cancer Biology, Dana-Farber Cancer Institute, and Department of Genetics, Harvard Medical School, 44 Binney Street, Boston, 02115 MA, USA
| | - Sander van den Heuvel
- Massachusetts General Hospital Cancer Center and Harvard Medical School, Building 149, 13th Street, Charlestown, 02129 MA, USA
- Department of Developmental Biology, Utrecht University, Kruytbuilding, Padualaan 8, 3584 CH Utrecht, The Netherlands
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Abstract
Oocytes and sperm are some of the most differentiated cells in our bodies, yet they generate all cell types after fertilization. Accumulating evidence suggests that this extraordinary potential is conferred to germ cells from the time of their formation during embryogenesis. In this Review, we describe common themes emerging from the study of germ cells in vertebrates and invertebrates. Transcriptional repression, chromatin remodeling, and an emphasis on posttranscriptional gene regulation preserve the totipotent genome of germ cells through generations.
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Affiliation(s)
- Geraldine Seydoux
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205, USA.
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Lublin AL, Evans TC. The RNA-binding proteins PUF-5, PUF-6, and PUF-7 reveal multiple systems for maternal mRNA regulation during C. elegans oogenesis. Dev Biol 2006; 303:635-49. [PMID: 17234175 DOI: 10.1016/j.ydbio.2006.12.004] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2006] [Revised: 11/25/2006] [Accepted: 12/02/2006] [Indexed: 02/04/2023]
Abstract
In metazoans, many mRNAs needed for embryogenesis are produced during oogenesis and must be tightly regulated during the complex events of oocyte development. In C. elegans, translation of the Notch receptor GLP-1 is repressed during oogenesis and is then activated specifically in anterior cells of the early embryo. The KH domain protein GLD-1 represses glp-1 translation during early stages of meiosis, but the factors that repress glp-1 during late oogenesis are not known. Here, we provide evidence that the PUF domain protein PUF-5 and two nearly identical PUF proteins PUF-6 and PUF-7 function during a specific period of oocyte differentiation to repress glp-1 and other maternal mRNAs. Depletion of PUF-5 and PUF-6/7 together caused defects in oocyte formation and early embryonic cell divisions. Loss of PUF-5 and PUF-6/7 also caused inappropriate expression of GLP-1 protein in oocytes, but GLP-1 remained repressed in meiotic germ cells. PUF-5 and PUF-6/7 function was required directly or indirectly for translational repression through elements of the glp-1 3' untranslated region. Oogenesis and embryonic defects could not be rescued by loss of GLP-1 activity, suggesting that PUF-5 and PUF-6/7 regulate other mRNAs in addition to glp-1. PUF-5 and PUF-6/7 depletion, however, did not perturb repression of the maternal factors GLD-1 and POS-1, suggesting that subsets of maternal gene products may be regulated by distinct pathways. Interestingly, PUF-5 protein was detected exclusively during mid to late oogenesis but became undetectable prior to completion of oocyte differentiation. These results reveal a previously unknown maternal mRNA control system that is specific to late stages of oogenesis and suggest new functions for PUF family proteins in post-mitotic differentiation. Multiple sets of RNA-binding complexes function in different domains of the C. elegans germ line to maintain silencing of Notch/glp-1 and other mRNAs.
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Affiliation(s)
- Alex L Lublin
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Mail Stop 8108, P.O. Box 6511, Aurora, CO 80045, USA
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Gonsalvez GB, Rajendra TK, Tian L, Matera AG. The Sm-protein methyltransferase, dart5, is essential for germ-cell specification and maintenance. Curr Biol 2006; 16:1077-89. [PMID: 16753561 DOI: 10.1016/j.cub.2006.04.037] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2006] [Revised: 04/20/2006] [Accepted: 04/21/2006] [Indexed: 11/28/2022]
Abstract
BACKGROUND The C-terminal tails of spliceosomal Sm proteins contain symmetrical dimethylarginine (sDMA) residues in vivo. The precise function of this posttranslational modification in the biogenesis of small nuclear ribonucleoproteins (snRNPs) and pre-mRNA splicing remains largely uncharacterized. Here, we examine the organismal and cellular consequences of loss of symmetric dimethylation of Sm proteins in Drosophila. RESULTS Genetic disruption of dart5, the fly ortholog of human PRMT5, results in the complete loss of sDMA residues on spliceosomal Sm proteins. Similarly, valois, a previously characterized grandchildless gene, is also required for sDMA modification of Sm proteins. In the absence of dart5, snRNP biogenesis is surprisingly unaffected, and homozygous mutant animals are completely viable. Instead, Dart5 protein is required for maturation of spermatocytes in males and for germ-cell specification in females. Embryos laid by dart5 mutants fail to form pole cells, and Tudor localization is disrupted in stage 10 oocytes. Transgenic expression of Dart5 exclusively within the female germline rescues pole-cell formation, whereas ubiquitous expression rescues sDMA modification of Sm proteins and male sterility. CONCLUSIONS We have shown that Dart5-mediated methylation of Sm proteins is not essential for snRNP biogenesis. The results uncover a novel role for dart5 in specification of the germline and in spermatocyte maturation. Because disruption of both dart5 and valois causes the specific loss of sDMA-modified Sm proteins and studies in C. elegans show that Sm proteins are required for germ-granule localization, we propose that Sm protein methylation is a pivotal event in germ-cell development.
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Affiliation(s)
- Graydon B Gonsalvez
- Department of Genetics, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4955, USA
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