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Contreras X, Depierre D, Akkawi C, Srbic M, Helsmoortel M, Nogaret M, LeHars M, Salifou K, Heurteau A, Cuvier O, Kiernan R. PAPγ associates with PAXT nuclear exosome to control the abundance of PROMPT ncRNAs. Nat Commun 2023; 14:6745. [PMID: 37875486 PMCID: PMC10598014 DOI: 10.1038/s41467-023-42620-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 10/17/2023] [Indexed: 10/26/2023] Open
Abstract
Pervasive transcription of the human genome generates an abundance of RNAs that must be processed and degraded. The nuclear RNA exosome is the main RNA degradation machinery in the nucleus. However, nuclear exosome must be recruited to its substrates by targeting complexes, such as NEXT or PAXT. By proteomic analysis, we identify additional subunits of PAXT, including many orthologs of MTREC found in S. pombe. In particular, we show that polyA polymerase gamma (PAPγ) associates with PAXT. Genome-wide mapping of the binding sites of ZFC3H1, RBM27 and PAPγ shows that PAXT is recruited to the TSS of hundreds of genes. Loss of ZFC3H1 abolishes recruitment of PAXT subunits including PAPγ to TSSs and concomitantly increases the abundance of PROMPTs at the same sites. Moreover, PAPγ, as well as MTR4 and ZFC3H1, is implicated in the polyadenylation of PROMPTs. Our results thus provide key insights into the direct targeting of PROMPT ncRNAs by PAXT at their genomic sites.
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Affiliation(s)
- Xavier Contreras
- CNRS-UMR 9002, Institute of Human Genetics (IGH)/University of Montpellier, Gene Regulation Lab, 34396, Montpellier, France
| | - David Depierre
- Center of Integrative Biology (CBI-CNRS), Molecular, Cellular and Developmental Biology (MCD Unit), University of Toulouse, 31000, Toulouse, France
| | - Charbel Akkawi
- CNRS-UMR 9002, Institute of Human Genetics (IGH)/University of Montpellier, Gene Regulation Lab, 34396, Montpellier, France
| | - Marina Srbic
- CNRS-UMR 9002, Institute of Human Genetics (IGH)/University of Montpellier, Gene Regulation Lab, 34396, Montpellier, France
| | - Marion Helsmoortel
- CNRS-UMR 9002, Institute of Human Genetics (IGH)/University of Montpellier, Gene Regulation Lab, 34396, Montpellier, France
| | - Maguelone Nogaret
- CNRS-UMR 9002, Institute of Human Genetics (IGH)/University of Montpellier, Gene Regulation Lab, 34396, Montpellier, France
| | - Matthieu LeHars
- CNRS-UMR 9002, Institute of Human Genetics (IGH)/University of Montpellier, Gene Regulation Lab, 34396, Montpellier, France
| | - Kader Salifou
- CNRS-UMR 9002, Institute of Human Genetics (IGH)/University of Montpellier, Gene Regulation Lab, 34396, Montpellier, France
| | - Alexandre Heurteau
- Center of Integrative Biology (CBI-CNRS), Molecular, Cellular and Developmental Biology (MCD Unit), University of Toulouse, 31000, Toulouse, France
| | - Olivier Cuvier
- Center of Integrative Biology (CBI-CNRS), Molecular, Cellular and Developmental Biology (MCD Unit), University of Toulouse, 31000, Toulouse, France
| | - Rosemary Kiernan
- CNRS-UMR 9002, Institute of Human Genetics (IGH)/University of Montpellier, Gene Regulation Lab, 34396, Montpellier, France.
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2
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Cai X, Rondeel I, Baumgartner S. Modulating the bicoid gradient in space and time. Hereditas 2021; 158:29. [PMID: 34404481 PMCID: PMC8371787 DOI: 10.1186/s41065-021-00192-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 07/19/2021] [Indexed: 11/15/2022] Open
Abstract
Background The formation of the Bicoid (Bcd) gradient in the early Drosophila is one of the most fascinating observations in biology and serves as a paradigm for gradient formation, yet its mechanism is still not fully understood. Two distinct models were proposed in the past, the SDD and the ARTS model. Results We define novel cis- and trans-acting factors that are indispensable for gradient formation. The first one is the poly A tail length of the bcd mRNA where we demonstrate that it changes not only in time, but also in space. We show that posterior bcd mRNAs possess a longer poly tail than anterior ones and this elongation is likely mediated by wispy (wisp), a poly A polymerase. Consequently, modulating the activity of Wisp results in changes of the Bcd gradient, in controlling downstream targets such as the gap and pair-rule genes, and also in influencing the cuticular pattern. Attempts to modulate the Bcd gradient by subjecting the egg to an extra nuclear cycle, i.e. a 15th nuclear cycle by means of the maternal haploid (mh) mutation showed no effect, neither on the appearance of the gradient nor on the control of downstream target. This suggests that the segmental anlagen are determined during the first 14 nuclear cycles. Finally, we identify the Cyclin B (CycB) gene as a trans-acting factor that modulates the movement of Bcd such that Bcd movement is allowed to move through the interior of the egg. Conclusions Our analysis demonstrates that Bcd gradient formation is far more complex than previously thought requiring a revision of the models of how the gradient is formed.
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Affiliation(s)
- Xiaoli Cai
- Departmentof Experimental Medical Sciences, Lund University, BMC D10, 22184, Lund, Sweden
| | - Inge Rondeel
- Departmentof Experimental Medical Sciences, Lund University, BMC D10, 22184, Lund, Sweden.,Present address: Hubrecht Institute, 3584 CT, Utrecht, The Netherlands
| | - Stefan Baumgartner
- Departmentof Experimental Medical Sciences, Lund University, BMC D10, 22184, Lund, Sweden. .,Department of Biology, University of Konstanz, 78457, Konstanz, Germany.
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Aboukilila MY, Sami JD, Wang J, England W, Spitale RC, Cleary MD. Identification of novel regulators of dendrite arborization using cell type-specific RNA metabolic labeling. PLoS One 2020; 15:e0240386. [PMID: 33264304 PMCID: PMC7710095 DOI: 10.1371/journal.pone.0240386] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 11/06/2020] [Indexed: 11/18/2022] Open
Abstract
Obtaining neuron transcriptomes is challenging; their complex morphology and interconnected microenvironments make it difficult to isolate neurons without potentially altering gene expression. Multidendritic sensory neurons (md neurons) of Drosophila larvae are commonly used to study peripheral nervous system biology, particularly dendrite arborization. We sought to test if EC-tagging, a biosynthetic RNA tagging and purification method that avoids the caveats of physical isolation, would enable discovery of novel regulators of md neuron dendrite arborization. Our aims were twofold: discover novel md neuron transcripts and test the sensitivity of EC-tagging. RNAs were biosynthetically tagged by expressing CD:UPRT (a nucleobase-converting fusion enzyme) in md neurons and feeding 5-ethynylcytosine (EC) to larvae. Only CD:UPRT-expressing cells are competent to convert EC into 5-ethynyluridine-monophosphate which is subsequently incorporated into nascent RNA transcripts. Tagged RNAs were purified and used for RNA-sequencing. Reference RNA was prepared in a similar manner using 5-ethynyluridine (EUd) to tag RNA in all cells and negative control RNA-seq was performed on "mock tagged" samples to identify non-specifically purified transcripts. Differential expression analysis identified md neuron enriched and depleted transcripts. Three candidate genes encoding RNA-binding proteins (RBPs) were tested for a role in md neuron dendrite arborization. Loss-of-function for the m6A-binding factor Ythdc1 did not cause any dendrite arborization defects while RNAi of the other two candidates, the poly(A) polymerase Hiiragi and the translation regulator Hephaestus, caused significant defects in dendrite arborization. This work provides an expanded view of transcription in md neurons and a technical framework for combining EC-tagging with RNA-seq to profile transcription in cells that may not be amenable to physical isolation.
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Affiliation(s)
- Mohamed Y. Aboukilila
- Department of Molecular and Cell Biology, Quantitative and Systems Biology Graduate Program, University of California, Merced, CA, United States of America
| | - Josephine D. Sami
- Department of Molecular and Cell Biology, Quantitative and Systems Biology Graduate Program, University of California, Merced, CA, United States of America
| | - Jingtian Wang
- Department of Pharmaceutical Sciences and Department of Chemistry, University of California, Irvine, CA, United States of America
| | - Whitney England
- Department of Pharmaceutical Sciences and Department of Chemistry, University of California, Irvine, CA, United States of America
| | - Robert C. Spitale
- Department of Pharmaceutical Sciences and Department of Chemistry, University of California, Irvine, CA, United States of America
| | - Michael D. Cleary
- Department of Molecular and Cell Biology, Quantitative and Systems Biology Graduate Program, University of California, Merced, CA, United States of America
- * E-mail:
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Olesnicky EC, Killian DJ. The cytoplasmic polyadenylation element binding protein (CPEB), Orb, is important for dendrite development and neuron fate specification in Drosophila melanogaster. Gene 2020; 738:144473. [PMID: 32057929 DOI: 10.1016/j.gene.2020.144473] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 02/05/2020] [Accepted: 02/11/2020] [Indexed: 12/14/2022]
Abstract
Cytoplasmic polyadenylation element binding proteins (CPEBs) are widely conserved proteins that regulate the length of poly(A) tails in the cytoplasm, regulate translation, and regulate mRNA transport. While CPEBs are best known for regulating maternal messages in oocytes, CPEBs also have roles in many other cell types including neurons. Here we extend our knowledge of the roles of CPEBs in neurons by showing that the Drosophila CPEB-encoding gene, orb, is required for proper dendrite development in larval sensory dendritic arborization neurons. Furthermore, we provide evidence that orb is important for neuron cell fate specification.
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Affiliation(s)
- Eugenia C Olesnicky
- Department of Biology, University of Colorado Colorado Springs, Colorado Springs, CO, 80918, United States.
| | - Darrell J Killian
- Department of Molecular Biology, Colorado College, Colorado Springs, CO 80903, United States
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5
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Maheshvara, a Conserved RNA Helicase, Regulates Notch Signaling in Drosophila melanogaster. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1227:69-79. [DOI: 10.1007/978-3-030-36422-9_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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6
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MiR-125b-2 Knockout in Testis Is Associated with Targeting to the PAP Gene, Mitochondrial Copy Number, and Impaired Sperm Quality. Int J Mol Sci 2019; 20:ijms20010148. [PMID: 30609807 PMCID: PMC6337273 DOI: 10.3390/ijms20010148] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 12/24/2018] [Accepted: 12/27/2018] [Indexed: 01/02/2023] Open
Abstract
It has been reported that the miR-125 family plays an important role in regulating embryo development. However, the function of miR-125b-2 in spermatogenesis remains unknown. In this study, we used a model of miR-125b knockout (KO) mice to study the relationship between miR-125b-2 and spermatogenesis. Among the KO mice, the progeny test showed that the litter size decreased significantly (p = 0.0002) and the rate of non-parous females increased significantly from 10% to 38%. At the same time, the testosterone concentration increased significantly (p = 0.007), with a remarkable decrease for estradiol (p = 0.02). Moreover, the sperm count decreased obviously (p = 0.011) and the percentage of abnormal sperm increased significantly (p = 0.0002). The testicular transcriptome sequencing revealed that there were 173 up-regulated genes, including Papolb (PAP), and 151 down-regulated genes in KO mice compared with wild type (WT). The Kyoto Encyclopedia of Genes and Genomes (KEGG) and gene ontology (GO) analysis showed that many of these genes were involved in sperm mitochondrial metabolism and other cellular biological processes. Meanwhile, the sperm mitochondria DNA (mtDNA) copy number increased significantly in the KO mice, but there were no changes observed in the mtDNA integrity and mutations of mt-Cytb, as well as the mt-ATP6 between the WT mice and KO mice. In the top 10 up-regulated genes, PAP, as a testis specific expressing gene, affect the process of spermatogenesis. Western blotting and the Luciferase assay validated that PAP was the target of miR-125b-5p. Intriguingly, we also found that both miR-125b and PAP were only highly expressed in the germ cells (GC) instead of in the Leydig cells (LC) and Sertoli cells (SC). Additionally, miR-125b-5p down regulated the secretion of testosterone in the TM3 cell by targeting PAP (p = 0.021). Our study firstly demonstrated that miR-125b-2 regulated testosterone secretion by directly targeting PAP, and increased the sperm mtDNA copy number to affect semen quality. The study indicated that miR-125b-2 had a positive influence on the reproductive performance of animals by regulating the expression of the PAP gene, and could be a potential drugs and diagnostic target for male infertility.
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7
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Jia Ng SS, Zheng RT, Osman I, Pek JW. Generation of Drosophila sisRNAs by Independent Transcription from Cognate Introns. iScience 2018; 4:68-75. [PMID: 30240754 PMCID: PMC6146417 DOI: 10.1016/j.isci.2018.05.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 04/25/2018] [Accepted: 05/14/2018] [Indexed: 01/26/2023] Open
Abstract
Although stable intronic sequence RNAs (sisRNAs) are conserved in plants and animals, their functional significance is still unclear. We identify a pool of polyadenylated maternally deposited sisRNAs in Drosophila melanogaster. These sisRNAs can be generated by independent transcription from the cognate introns. The ovary-specific poly(A) polymerase Wispy mediates the polyadenylation of maternal sisRNAs and confers their stability as maternal transcripts. A developmentally regulated sisRNA sisR-3 represses the expression of a long noncoding RNA CR44148 and is required during development. Our results expand the pool of sisRNAs and suggest that sisRNAs perform regulatory functions during development in Drosophila. Identification of polyadenylated sisRNAs sisRNAs can be produced from independent transcription sisR-3 regulates a long noncoding RNA sisR-3 is required during development
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Affiliation(s)
- Sharon Si Jia Ng
- Temasek Polytechnic, 21 Tampines Avenue 1, Singapore 529757, Singapore
| | - Ruther Teo Zheng
- Ngee Ann Polytechnic, 535 Clementi Road, Singapore 599489, Singapore
| | - Ismail Osman
- Temasek Life Sciences Laboratory, National University of Singapore, 1 Research Link, Singapore 117604, Singapore; Department of Biological Sciences, National University of Singapore 117543, Singapore, Singapore
| | - Jun Wei Pek
- Temasek Life Sciences Laboratory, National University of Singapore, 1 Research Link, Singapore 117604, Singapore.
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8
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The Pax protein Eyegone (Eyg) interacts with the pi-RNA component Aubergine (Aub) and controls egg chamber development in Drosophila. Dev Biol 2018; 434:267-277. [PMID: 29278721 DOI: 10.1016/j.ydbio.2017.12.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Revised: 12/15/2017] [Accepted: 12/18/2017] [Indexed: 11/20/2022]
Abstract
The eyegone (eyg) gene encodes Eyg, a transcription factor of the Pax family with multiple roles during Drosophila development. Eyg has been shown to be nuclear in the cells where it functions. In this report we describe a new functional cytoplasmic distribution of Eyg during egg chamber development in the female ovarioles. The protein is present from the germarium until stage 10 of cyst development. The majority of egg chambers that develop in the absence of Eyg arrest their development before stage 10, show augmented levels of the telomeric retro-transposon TART-A and low levels of heterochromatin marks in the oocyte nucleus. During the maternal to zygotic transition (MTZ) Eyg seems to play a role in destabilizing germ cell less (gcl) and oo 16 RNA binding protein (orb) mRNAs. We were able to show that Eyg interacts with Aubergine (Aub), a component of the pi-RNA pathway during egg chamber development. This interaction could be essential for Eyg to be retained in the cytoplasm and fulfill its functions there.
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9
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Hall H, Medina P, Cooper DA, Escobedo SE, Rounds J, Brennan KJ, Vincent C, Miura P, Doerge R, Weake VM. Transcriptome profiling of aging Drosophila photoreceptors reveals gene expression trends that correlate with visual senescence. BMC Genomics 2017; 18:894. [PMID: 29162050 PMCID: PMC5698953 DOI: 10.1186/s12864-017-4304-3] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Accepted: 11/14/2017] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Aging is associated with functional decline of neurons and increased incidence of both neurodegenerative and ocular disease. Photoreceptor neurons in Drosophila melanogaster provide a powerful model for studying the molecular changes involved in functional senescence of neurons since decreased visual behavior precedes retinal degeneration. Here, we sought to identify gene expression changes and the genomic features of differentially regulated genes in photoreceptors that contribute to visual senescence. RESULTS To identify gene expression changes that could lead to visual senescence, we characterized the aging transcriptome of Drosophila sensory neurons highly enriched for photoreceptors. We profiled the nuclear transcriptome of genetically-labeled photoreceptors over a 40 day time course and identified increased expression of genes involved in stress and DNA damage response, and decreased expression of genes required for neuronal function. We further show that combinations of promoter motifs robustly identify age-regulated genes, suggesting that transcription factors are important in driving expression changes in aging photoreceptors. However, long, highly expressed and heavily spliced genes are also more likely to be downregulated with age, indicating that other mechanisms could contribute to expression changes at these genes. Lastly, we identify that circular RNAs (circRNAs) strongly increase during aging in photoreceptors. CONCLUSIONS Overall, we identified changes in gene expression in aging Drosophila photoreceptors that could account for visual senescence. Further, we show that genomic features predict these age-related changes, suggesting potential mechanisms that could be targeted to slow the rate of age-associated visual decline.
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Affiliation(s)
- Hana Hall
- Department of Biochemistry, Purdue University, West Lafayette, IN, 47907, USA
| | - Patrick Medina
- Department of Statistics, Purdue University, West Lafayette, IN, 47907, USA
| | - Daphne A Cooper
- Department of Biology, University of Nevada, Reno, NV, 89557, USA
| | - Spencer E Escobedo
- Department of Biochemistry, Purdue University, West Lafayette, IN, 47907, USA
| | - Jeremiah Rounds
- Department of Statistics, Purdue University, West Lafayette, IN, 47907, USA
| | - Kaelan J Brennan
- Department of Biochemistry, Purdue University, West Lafayette, IN, 47907, USA
| | | | - Pedro Miura
- Department of Biology, University of Nevada, Reno, NV, 89557, USA
| | | | - Vikki M Weake
- Department of Biochemistry, Purdue University, West Lafayette, IN, 47907, USA. .,Purdue University Center for Cancer Research, Purdue University, West Lafayette, 47907, USA.
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Localized Translation of gurken/TGF-α mRNA during Axis Specification Is Controlled by Access to Orb/CPEB on Processing Bodies. Cell Rep 2016; 14:2451-62. [PMID: 26947065 PMCID: PMC4823467 DOI: 10.1016/j.celrep.2016.02.038] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Revised: 12/18/2015] [Accepted: 02/03/2016] [Indexed: 12/31/2022] Open
Abstract
In Drosophila oocytes, gurken/TGF-α mRNA is essential for establishing the future embryonic axes. gurken remains translationally silent during transport from its point of synthesis in nurse cells to its final destination in the oocyte, where it associates with the edge of processing bodies. Here we show that, in nurse cells, gurken is kept translationally silent by the lack of sufficient Orb/CPEB, its translational activator. Processing bodies in nurse cells have a similar protein complement and ultrastructure to those in the oocyte, but they markedly less Orb and do not associate with gurken mRNA. Ectopic expression of Orb in nurse cells at levels similar to the wild-type oocyte dorso-anterior corner at mid-oogenesis is sufficient to cause gurken mRNA to associate with processing bodies and translate prematurely. We propose that controlling the spatial distribution of translational activators is a fundamental mechanism for regulating localized translation. gurken mRNA is not silenced by known repressors during its transport In nurse cells, gurken mRNA is not associated with processing bodies In nurse cells, lack of sufficient Orb/CPEB silences gurken mRNA translation In oocytes, gurken mRNA is associated with Orb on processing bodies and translated
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11
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Rojas-Ríos P, Chartier A, Pierson S, Séverac D, Dantec C, Busseau I, Simonelig M. Translational Control of Autophagy by Orb in the Drosophila Germline. Dev Cell 2015; 35:622-631. [DOI: 10.1016/j.devcel.2015.11.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Revised: 09/02/2015] [Accepted: 11/04/2015] [Indexed: 11/16/2022]
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12
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Norvell A, Wong J, Randolph K, Thompson L. Wispy and Orb cooperate in the cytoplasmic polyadenylation of localizedgurkenmRNA. Dev Dyn 2015. [DOI: 10.1002/dvdy.24311] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Affiliation(s)
- Amanda Norvell
- Department of Biology; The College of New Jersey; Ewing New Jersey
| | - Jason Wong
- Department of Biology; The College of New Jersey; Ewing New Jersey
| | - Kristen Randolph
- Department of Biology; The College of New Jersey; Ewing New Jersey
| | - Letitia Thompson
- Department of Biology; The College of New Jersey; Ewing New Jersey
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13
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Genome-Wide Analysis of PAPS1-Dependent Polyadenylation Identifies Novel Roles for Functionally Specialized Poly(A) Polymerases in Arabidopsis thaliana. PLoS Genet 2015; 11:e1005474. [PMID: 26305463 PMCID: PMC4549238 DOI: 10.1371/journal.pgen.1005474] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Accepted: 07/28/2015] [Indexed: 11/29/2022] Open
Abstract
The poly(A) tail at 3’ ends of eukaryotic mRNAs promotes their nuclear export, stability and translational efficiency, and changes in its length can strongly impact gene expression. The Arabidopsis thaliana genome encodes three canonical nuclear poly(A) polymerases, PAPS1, PAPS2 and PAPS4. As shown by their different mutant phenotypes, these three isoforms are functionally specialized, with PAPS1 modifying organ growth and suppressing a constitutive immune response. However, the molecular basis of this specialization is largely unknown. Here, we have estimated poly(A)-tail lengths on a transcriptome-wide scale in wild-type and paps1 mutants. This identified categories of genes as particularly strongly affected in paps1 mutants, including genes encoding ribosomal proteins, cell-division factors and major carbohydrate-metabolic proteins. We experimentally verified two novel functions of PAPS1 in ribosome biogenesis and redox homoeostasis that were predicted based on the analysis of poly(A)-tail length changes in paps1 mutants. When overlaying the PAPS1-dependent effects observed here with coexpression analysis based on independent microarray data, the two clusters of transcripts that are most closely coexpressed with PAPS1 show the strongest change in poly(A)-tail length and transcript abundance in paps1 mutants in our analysis. This suggests that their coexpression reflects at least partly the preferential polyadenylation of these transcripts by PAPS1 versus the other two poly(A)-polymerase isoforms. Thus, transcriptome-wide analysis of poly(A)-tail lengths identifies novel biological functions and likely target transcripts for polyadenylation by PAPS1. Data integration with large-scale co-expression data suggests that changes in the relative activities of the isoforms are used as an endogenous mechanism to co-ordinately modulate plant gene expression. The poly(A) tail of eukaryotic mRNAs promotes export from the nucleus, translation in the cytoplasm and stability of the mRNA, and changes in poly(A)-tail length can strongly impact on gene expression. The Arabidopsis thaliana genome encodes three nuclear canonical poly(A) polymerases (PAPS1, PAPS2, PAPS4) that fulfill different functions, presumably by preferentially polyadenylating certain subpopulations of pre-mRNAs. Here, we use a fractionation-based technique to assess the transcriptome-wide impact of reduced PAPS1 activity and identify functional classes of transcripts that are particularly sensitive to reduced PAPS1 activity. Analysis of these transcripts identifies two novel biological functions for PAPS1 in ribosome biogenesis and in redox homeostasis that we confirm experimentally. By overlaying our results with information about genome-wide co-expression, we demonstrate that genes co-expressed with PAPS1 are the most strongly affected in terms of poly(A)-tail length and total-abundance changes in the paps1 mutants. This provides strong evidence that the co-expression of these genes with PAPS1 that is seen across thousands of microarrays is at least partly caused by altered activity of the PAPS1 isoform, suggesting that the plant indeed uses modulation of the balance of isoform activities to coordinately regulate the expression of groups of genes.
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14
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Chartier A, Klein P, Pierson S, Barbezier N, Gidaro T, Casas F, Carberry S, Dowling P, Maynadier L, Bellec M, Oloko M, Jardel C, Moritz B, Dickson G, Mouly V, Ohlendieck K, Butler-Browne G, Trollet C, Simonelig M. Mitochondrial dysfunction reveals the role of mRNA poly(A) tail regulation in oculopharyngeal muscular dystrophy pathogenesis. PLoS Genet 2015; 11:e1005092. [PMID: 25816335 PMCID: PMC4376527 DOI: 10.1371/journal.pgen.1005092] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Accepted: 02/23/2015] [Indexed: 01/25/2023] Open
Abstract
Oculopharyngeal muscular dystrophy (OPMD), a late-onset disorder characterized by progressive degeneration of specific muscles, results from the extension of a polyalanine tract in poly(A) binding protein nuclear 1 (PABPN1). While the roles of PABPN1 in nuclear polyadenylation and regulation of alternative poly(A) site choice are established, the molecular mechanisms behind OPMD remain undetermined. Here, we show, using Drosophila and mouse models, that OPMD pathogenesis depends on affected poly(A) tail lengths of specific mRNAs. We identify a set of mRNAs encoding mitochondrial proteins that are down-regulated starting at the earliest stages of OPMD progression. The down-regulation of these mRNAs correlates with their shortened poly(A) tails and partial rescue of their levels when deadenylation is genetically reduced improves muscle function. Genetic analysis of candidate genes encoding RNA binding proteins using the Drosophila OPMD model uncovers a potential role of a number of them. We focus on the deadenylation regulator Smaug and show that it is expressed in adult muscles and specifically binds to the down-regulated mRNAs. In addition, the first step of the cleavage and polyadenylation reaction, mRNA cleavage, is affected in muscles expressing alanine-expanded PABPN1. We propose that impaired cleavage during nuclear cleavage/polyadenylation is an early defect in OPMD. This defect followed by active deadenylation of specific mRNAs, involving Smaug and the CCR4-NOT deadenylation complex, leads to their destabilization and mitochondrial dysfunction. These results broaden our understanding of the role of mRNA regulation in pathologies and might help to understand the molecular mechanisms underlying neurodegenerative disorders that involve mitochondrial dysfunction. Oculopharyngeal muscular dystrophy is a genetic disease characterized by progressive degeneration of specific muscles, leading to ptosis (eyelid drooping), dysphagia (swallowing difficulties) and proximal limb weakness. The disease results from mutations in a nuclear protein called poly(A) binding protein nuclear 1 that is involved in polyadenylation of messenger RNAs (mRNAs) and poly(A) site selection. To address the molecular mechanisms involved in the disease, we have used two animal models (Drosophila and mouse) that recapitulate the features of this disorder. We show that oculopharyngeal muscular dystrophy pathogenesis depends on defects in poly(A) tail length regulation of specific mRNAs. Because poly(A) tails play an essential role in mRNA stability, these defects result in accelerated decay of these mRNAs. The affected mRNAs encode mitochondrial proteins, and mitochondrial activity is impaired in diseased muscles. These findings have important implications for the development of potential therapies for oculopharyngeal muscular dystrophy, and might be relevant to decipher the molecular mechanisms underlying other disorders that involve mitochondrial dysfunction.
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Affiliation(s)
- Aymeric Chartier
- mRNA Regulation and Development, Institut de Génétique Humaine, CNRS UPR1142, Montpellier, France
| | - Pierre Klein
- Sorbonne Universités, UPMC Univ Paris 06, UM76, INSERM UMRS974, CNRS FRE3617, Center for Research in Myology, Paris, France
| | - Stéphanie Pierson
- mRNA Regulation and Development, Institut de Génétique Humaine, CNRS UPR1142, Montpellier, France
| | - Nicolas Barbezier
- mRNA Regulation and Development, Institut de Génétique Humaine, CNRS UPR1142, Montpellier, France
| | - Teresa Gidaro
- Sorbonne Universités, UPMC Univ Paris 06, UM76, INSERM UMRS974, CNRS FRE3617, Center for Research in Myology, Paris, France
| | - François Casas
- INRA, UMR 866 Différenciation cellulaire et croissance, Montpellier, France
| | - Steven Carberry
- Department of Biology, National University of Ireland, Maynooth, Ireland
| | - Paul Dowling
- Department of Biology, National University of Ireland, Maynooth, Ireland
| | - Laurie Maynadier
- mRNA Regulation and Development, Institut de Génétique Humaine, CNRS UPR1142, Montpellier, France
| | - Maëlle Bellec
- mRNA Regulation and Development, Institut de Génétique Humaine, CNRS UPR1142, Montpellier, France
| | - Martine Oloko
- Sorbonne Universités, UPMC Univ Paris 06, UM76, INSERM UMRS974, CNRS FRE3617, Center for Research in Myology, Paris, France
| | - Claude Jardel
- Service de Biochimie Métabolique et Centre de Génétique moléculaire et chromosomique, INSERM U1016, Institut Cochin, CNRS UMR 8104, AP-HP, GHU Pitié-Salpêtrière, Paris, France
| | - Bodo Moritz
- Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Halle, Germany
| | - George Dickson
- School of Biological Sciences, Royal Holloway - University of London, Egham, Surrey, United Kingdom
| | - Vincent Mouly
- Sorbonne Universités, UPMC Univ Paris 06, UM76, INSERM UMRS974, CNRS FRE3617, Center for Research in Myology, Paris, France
| | - Kay Ohlendieck
- Department of Biology, National University of Ireland, Maynooth, Ireland
| | - Gillian Butler-Browne
- Sorbonne Universités, UPMC Univ Paris 06, UM76, INSERM UMRS974, CNRS FRE3617, Center for Research in Myology, Paris, France
| | - Capucine Trollet
- Sorbonne Universités, UPMC Univ Paris 06, UM76, INSERM UMRS974, CNRS FRE3617, Center for Research in Myology, Paris, France
| | - Martine Simonelig
- mRNA Regulation and Development, Institut de Génétique Humaine, CNRS UPR1142, Montpellier, France
- * E-mail:
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15
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Li XQ, Du D. Motif types, motif locations and base composition patterns around the RNA polyadenylation site in microorganisms, plants and animals. BMC Evol Biol 2014; 14:162. [PMID: 25052519 PMCID: PMC4360255 DOI: 10.1186/s12862-014-0162-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Accepted: 07/14/2014] [Indexed: 12/22/2022] Open
Abstract
Background The polyadenylation of RNA is critical for gene functioning, but the conserved sequence motifs (often called signal or signature motifs), motif locations and abundances, and base composition patterns around mRNA polyadenylation [poly(A)] sites are still uncharacterized in most species. The evolutionary tendency for poly(A) site selection is still largely unknown. Results We analyzed the poly(A) site regions of 31 species or phyla. Different groups of species showed different poly(A) signal motifs: UUACUU at the poly(A) site in the parasite Trypanosoma cruzi; UGUAAC (approximately 13 bases upstream of the site) in the alga Chlamydomonas reinhardtii; UGUUUG (or UGUUUGUU) at mainly the fourth base downstream of the poly(A) site in the parasite Blastocystis hominis; and AAUAAA at approximately 16 bases and approximately 19 bases upstream of the poly(A) site in animals and plants, respectively. Polyadenylation signal motifs are usually several hundred times more abundant around poly(A) sites than in whole genomes. These predominant motifs usually had very specific locations, whether upstream of, at, or downstream of poly(A) sites, depending on the species or phylum. The poly(A) site was usually an adenosine (A) in all analyzed species except for B. hominis, and there was weak A predominance in C. reinhardtii. Fungi, animals, plants, and the protist Phytophthora infestans shared a general base abundance pattern (or base composition pattern) of “U-rich—A-rich—U-rich—Poly(A) site—U-rich regions”, or U-A-U-A-U for short, with some variation for each kingdom or subkingdom. Conclusion This study identified the poly(A) signal motifs, motif locations, and base composition patterns around mRNA poly(A) sites in protists, fungi, plants, and animals and provided insight into poly(A) site evolution.
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Affiliation(s)
- Xiu-Qing Li
- Molecular Genetics Laboratory, Potato Research Centre, Agriculture and Agri-Food Canada, 850 Lincoln Road, Fredericton, New Brunswick, E3B 4Z7, Canada.
| | - Donglei Du
- Quantitative Methods Research Group, Faculty of Business Administration, University of New Brunswick, 7 Macaulay Lane, Fredericton, NB, E3B 5A3, Canada.
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16
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Ivshina M, Lasko P, Richter JD. Cytoplasmic polyadenylation element binding proteins in development, health, and disease. Annu Rev Cell Dev Biol 2014; 30:393-415. [PMID: 25068488 DOI: 10.1146/annurev-cellbio-101011-155831] [Citation(s) in RCA: 154] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The cytoplasmic polyadenylation element binding (CPEB) proteins are sequence-specific mRNA binding proteins that control translation in development, health, and disease. CPEB1, the founding member of this family, has become an important model for illustrating general principles of translational control by cytoplasmic polyadenylation in gametogenesis, cancer etiology, synaptic plasticity, learning, and memory. Although the biological functions of the other members of this protein family in vertebrates are just beginning to emerge, it is already evident that they, too, mediate important processes, such as cancer etiology and higher cognitive function. In Drosophila, the CPEB proteins Orb and Orb2 play key roles in oogenesis and in neuronal function, as do related proteins in Caenorhabditis elegans and Aplysia. We review the biochemical features of the CPEB proteins, discuss their activities in several biological systems, and illustrate how understanding CPEB activity in model organisms has an important impact on neurological disease.
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Affiliation(s)
- Maria Ivshina
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605;
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17
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Li XQ. Comparative analysis of the base compositions of the pre-mRNA 3' cleaved-off region and the mRNA 3' untranslated region relative to the genomic base composition in animals and plants. PLoS One 2014; 9:e99928. [PMID: 24941005 PMCID: PMC4062462 DOI: 10.1371/journal.pone.0099928] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2013] [Accepted: 05/20/2014] [Indexed: 12/26/2022] Open
Abstract
The precursor messenger RNA (pre-mRNA) three-prime cleaved-off region (3′COR) and the mRNA three-prime untranslated region (3′UTR) play critical roles in regulating gene expression. The differences in base composition between these regions and the corresponding genomes are still largely uncharacterized in animals and plants. In this study, the base compositions of non-redundant 3′CORs and 3′UTRs were compared with the corresponding whole genomes of eleven animals, four dicotyledonous plants, and three monocotyledonous (cereal) plants. Among the four bases (A, C, G, and U for adenine, cytosine, guanine, and uracil, respectively), U (which corresponds to T, for thymine, in DNA) was the most frequent, A the second most frequent, G the third most frequent, and C the least frequent in most of the species in both the 3′COR and 3′UTR regions. In comparison with the whole genomes, in both regions the U content was usually the most overrepresented (particularly in the monocotyledonous plants), and the C content was the most underrepresented. The order obtained for the species groups, when ranked from high to low according to the U contents in the 3′COR and 3′UTR was as follows: dicotyledonous plants, monocotyledonous plants, non-mammal animals, and mammals. In contrast, the genomic T content was highest in dicotyledonous plants, lowest in monocotyledonous plants, and intermediate in animals. These results suggest the following: 1) there is a mechanism operating in both animals and plants which is biased toward U and against C in the 3′COR and 3′UTR; 2) the 3′UTR and 3′COR, as functional units, minimized the difference between dicotyledonous and monocotyledonous plants, while the dicotyledonous and monocotyledonous genomes evolved into two extreme groups in terms of base composition.
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Affiliation(s)
- Xiu-Qing Li
- Potato Research Centre, Agriculture and Agri-Food Canada, Fredericton, New Brunswick, Canada
- * E-mail:
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18
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Pachytene piRNAs instruct massive mRNA elimination during late spermiogenesis. Cell Res 2014; 24:680-700. [PMID: 24787618 PMCID: PMC4042167 DOI: 10.1038/cr.2014.41] [Citation(s) in RCA: 267] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Revised: 02/26/2014] [Accepted: 03/02/2014] [Indexed: 12/12/2022] Open
Abstract
Spermatogenesis in mammals is characterized by two waves of piRNA expression: one corresponds to classic piRNAs responsible for silencing retrotransponsons and the second wave is predominantly derived from nontransposon intergenic regions in pachytene spermatocytes, but the function of these pachytene piRNAs is largely unknown. Here, we report the involvement of pachytene piRNAs in instructing massive mRNA elimination in mouse elongating spermatids (ES). We demonstrate that a piRNA-induced silencing complex (pi-RISC) containing murine PIWI (MIWI) and deadenylase CAF1 is selectively assembled in ES, which is responsible for inducing mRNA deadenylation and decay via a mechanism that resembles the action of miRNAs in somatic cells. Such a highly orchestrated program appears to take full advantage of the enormous repertoire of diversified targeting capacity of pachytene piRNAs derived from nontransposon intergenic regions. These findings suggest that pachytene piRNAs are responsible for inactivating vast cellular programs in preparation for sperm production from ES.
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19
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Yang Q, Nausch L, Martin G, Keller W, Doublié S. Crystal structure of human poly(A) polymerase gamma reveals a conserved catalytic core for canonical poly(A) polymerases. J Mol Biol 2014; 426:43-50. [PMID: 24076191 PMCID: PMC3878066 DOI: 10.1016/j.jmb.2013.09.025] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Revised: 09/19/2013] [Accepted: 09/20/2013] [Indexed: 01/07/2023]
Abstract
In eukaryotes, the poly(A) tail added at the 3' end of an mRNA precursor is essential for the regulation of mRNA stability and the initiation of translation. Poly(A) polymerase (PAP) is the enzyme that catalyzes the poly(A) addition reaction. Multiple isoforms of PAP have been identified in vertebrates, which originate from gene duplication, alternative splicing or post-translational modifications. The complexity of PAP isoforms suggests that they might play different roles in the cell. Phylogenetic studies indicate that vertebrate PAPs are grouped into three clades termed α, β and γ, which originated from two gene duplication events. To date, all the available PAP structures are from the PAPα clade. Here, we present the crystal structure of the first representative of the PAPγ clade, human PAPγ bound to cordycepin triphosphate (3'dATP) and Ca(2+). The structure revealed that PAPγ closely resembles its PAPα ortholog. An analysis of residue conservation reveals a conserved catalytic binding pocket, whereas residues at the surface of the polymerase are more divergent.
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Affiliation(s)
- Qin Yang
- Department of Microbiology and Molecular Genetics, University of Vermont, Stafford Hall, 95 Carrigan Drive, Burlington VT 05405-0068, USA
| | - Lydia Nausch
- Department of Microbiology and Molecular Genetics, University of Vermont, Stafford Hall, 95 Carrigan Drive, Burlington VT 05405-0068, USA
| | - Georges Martin
- Computational and Systems Biology, Biozentrum, University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland
| | - Walter Keller
- Computational and Systems Biology, Biozentrum, University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland
| | - Sylvie Doublié
- Department of Microbiology and Molecular Genetics, University of Vermont, Stafford Hall, 95 Carrigan Drive, Burlington VT 05405-0068, USA,Corresponding author: , Phone: +1-802-656-9531, Fax: +1-802-656-8749
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20
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Charlesworth A, Meijer HA, de Moor CH. Specificity factors in cytoplasmic polyadenylation. WILEY INTERDISCIPLINARY REVIEWS-RNA 2014; 4:437-61. [PMID: 23776146 PMCID: PMC3736149 DOI: 10.1002/wrna.1171] [Citation(s) in RCA: 112] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Revised: 04/08/2013] [Accepted: 04/09/2013] [Indexed: 12/12/2022]
Abstract
Poly(A) tail elongation after export of an messenger RNA (mRNA) to the cytoplasm is called cytoplasmic polyadenylation. It was first discovered in oocytes and embryos, where it has roles in meiosis and development. In recent years, however, has been implicated in many other processes, including synaptic plasticity and mitosis. This review aims to introduce cytoplasmic polyadenylation with an emphasis on the factors and elements mediating this process for different mRNAs and in different animal species. We will discuss the RNA sequence elements mediating cytoplasmic polyadenylation in the 3' untranslated regions of mRNAs, including the CPE, MBE, TCS, eCPE, and C-CPE. In addition to describing the role of general polyadenylation factors, we discuss the specific RNA binding protein families associated with cytoplasmic polyadenylation elements, including CPEB (CPEB1, CPEB2, CPEB3, and CPEB4), Pumilio (PUM2), Musashi (MSI1, MSI2), zygote arrest (ZAR2), ELAV like proteins (ELAVL1, HuR), poly(C) binding proteins (PCBP2, αCP2, hnRNP-E2), and Bicaudal C (BICC1). Some emerging themes in cytoplasmic polyadenylation will be highlighted. To facilitate understanding for those working in different organisms and fields, particularly those who are analyzing high throughput data, HUGO gene nomenclature for the human orthologs is used throughout. Where human orthologs have not been clearly identified, reference is made to protein families identified in man.
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Affiliation(s)
- Amanda Charlesworth
- Department of Integrative Biology, University of Colorado Denver, Denver, CO, USA
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21
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Li XQ, Du D. RNA polyadenylation sites on the genomes of microorganisms, animals, and plants. PLoS One 2013; 8:e79511. [PMID: 24260238 PMCID: PMC3832601 DOI: 10.1371/journal.pone.0079511] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Accepted: 09/29/2013] [Indexed: 01/15/2023] Open
Abstract
Pre–messenger RNA (mRNA) 3′-end cleavage and subsequent polyadenylation strongly regulate gene expression. In comparison with the upstream or downstream motifs, relatively little is known about the feature differences of polyadenylation [poly(A)] sites among major kingdoms. We suspect that the precise poly(A) sites are very selective, and we therefore mapped mRNA poly(A) sites on complete and nearly complete genomes using mRNA sequences available in the National Center for Biotechnology Information (NCBI) Nucleotide database. In this paper, we describe the mRNA nucleotide [i.e., the poly(A) tail attachment position] that is directly in attachment with the poly(A) tail and the pre-mRNA nucleotide [i.e., the poly(A) tail starting position] that corresponds to the first adenosine of the poly(A) tail in the 29 most-mapped species (2 fungi, 2 protists, 18 animals, and 7 plants). The most representative pre-mRNA dinucleotides covering these two positions were UA, CA, and GA in 17, 10, and 2 of the species, respectively. The pre-mRNA nucleotide at the poly(A) tail starting position was typically an adenosine [i.e., A-type poly(A) sites], sometimes a uridine, and occasionally a cytidine or guanosine. The order was U>C>G at the attachment position but A>>U>C≥G at the starting position. However, in comparison with the mRNA nucleotide composition (base composition), the poly(A) tail attachment position selected C over U in plants and both C and G over U in animals, in both A-type and non-A-type poly(A) sites. Animals, dicot plants, and monocot plants had clear differences in C/G ratios at the poly(A) tail attachment position of the non-A-type poly(A) sites. This study of poly(A) site evolution indicated that the two positions within poly(A) sites had distinct nucleotide compositions and were different among kingdoms.
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Affiliation(s)
- Xiu-Qing Li
- Molecular Genetics Laboratory, Potato Research Centre, Agriculture and Agri-Food Canada, Fredericton, New Brunswick, Canada
- * E-mail:
| | - Donglei Du
- Quantitative Methods Research Group, Faculty of Business Administration, University of New Brunswick, Fredericton, New Brunswick, Canada
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22
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Joly W, Chartier A, Rojas-Rios P, Busseau I, Simonelig M. The CCR4 deadenylase acts with Nanos and Pumilio in the fine-tuning of Mei-P26 expression to promote germline stem cell self-renewal. Stem Cell Reports 2013; 1:411-24. [PMID: 24286029 PMCID: PMC3841267 DOI: 10.1016/j.stemcr.2013.09.007] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 09/26/2013] [Accepted: 09/27/2013] [Indexed: 11/28/2022] Open
Abstract
Translational regulation plays an essential role in Drosophila ovarian germline stem cell (GSC) biology. GSC self-renewal requires two translational repressors, Nanos (Nos) and Pumilio (Pum), which repress the expression of differentiation factors in the stem cells. The molecular mechanisms underlying this translational repression remain unknown. Here, we show that the CCR4 deadenylase is required for GSC self-renewal and that Nos and Pum act through its recruitment onto specific mRNAs. We identify mei-P26 mRNA as a direct and major target of Nos/Pum/CCR4 translational repression in the GSCs. mei-P26 encodes a protein of the Trim-NHL tumor suppressor family that has conserved functions in stem cell lineages. We show that fine-tuning Mei-P26 expression by CCR4 plays a key role in GSC self-renewal. These results identify the molecular mechanism of Nos/Pum function in GSC self-renewal and reveal the role of CCR4-NOT-mediated deadenylation in regulating the balance between GSC self-renewal and differentiation. The CCR4 deadenylase is required for female germline stem cell self-renewal Nos/Pum recruit CCR4-NOT for translational repression in germline stem cells mei-P26 mRNA is a major target of translational repression by Nos/Pum/CCR4 Fine-tuning of mei-P26 by CCR4 is required for germline stem cell self-renewal
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Affiliation(s)
- Willy Joly
- mRNA Regulation and Development, Institute of Human Genetics, CNRS UPR1142, 141 Rue de la Cardonille, 34396 Montpellier Cedex 5, France
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23
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The human nuclear poly(a)-binding protein promotes RNA hyperadenylation and decay. PLoS Genet 2013; 9:e1003893. [PMID: 24146636 PMCID: PMC3798265 DOI: 10.1371/journal.pgen.1003893] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Accepted: 09/05/2013] [Indexed: 12/05/2022] Open
Abstract
Control of nuclear RNA stability is essential for proper gene expression, but the mechanisms governing RNA degradation in mammalian nuclei are poorly defined. In this study, we uncover a mammalian RNA decay pathway that depends on the nuclear poly(A)-binding protein (PABPN1), the poly(A) polymerases (PAPs), PAPα and PAPγ, and the exosome subunits RRP6 and DIS3. Using a targeted knockdown approach and nuclear RNA reporters, we show that PABPN1 and PAPα, redundantly with PAPγ, generate hyperadenylated decay substrates that are recognized by the exosome and degraded. Poly(A) tail extension appears to be necessary for decay, as cordycepin treatment or point mutations in the PAP-stimulating domain of PABPN1 leads to the accumulation of stable transcripts with shorter poly(A) tails than controls. Mechanistically, these data suggest that PABPN1-dependent promotion of PAP activity can stimulate nuclear RNA decay. Importantly, efficiently exported RNAs are unaffected by this decay pathway, supporting an mRNA quality control function for this pathway. Finally, analyses of both bulk poly(A) tails and specific endogenous transcripts reveals that a subset of nuclear RNAs are hyperadenylated in a PABPN1-dependent fashion, and this hyperadenylation can be either uncoupled or coupled with decay. Our results highlight a complex relationship between PABPN1, PAPα/γ, and nuclear RNA decay, and we suggest that these activities may play broader roles in the regulation of human gene expression. In eukaryotes, mRNAs include a stretch of adenosine nucleotides at their 3′ end termed the poly(A) tail. In the cytoplasm, the poly(A) tail stimulates translation of the mRNA into protein, and protects the transcript from degradation. Evidence suggests that poly(A) tails may play distinct roles in RNA metabolism in the nucleus, but little is known about these functions and mechanisms. We show here that poly(A) tails can stimulate transcript decay in the nucleus, a function mediated by the ubiquitous nuclear poly(A) binding protein PABPN1. We find that PABPN1 is required for the degradation of a viral nuclear noncoding RNA as well as an inefficiently exported human mRNA. Importantly, the targeting of RNAs to this decay pathway requires the PABPN1 and poly(A) polymerase-dependent extension of the poly(A) tail. Nuclear transcripts with longer poly(A) tails are then selectively degraded by components of the nuclear exosome. These studies elucidate mechanisms that mammalian cells use to ensure proper mRNA “quality control” and may be important to regulate the expression of nuclear noncoding RNAs. Furthermore, our results suggest that the poly(A) tail has diverse and context-specific roles in gene expression.
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24
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Target specificity among canonical nuclear poly(A) polymerases in plants modulates organ growth and pathogen response. Proc Natl Acad Sci U S A 2013; 110:13994-9. [PMID: 23918356 DOI: 10.1073/pnas.1303967110] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Polyadenylation of pre-mRNAs is critical for efficient nuclear export, stability, and translation of the mature mRNAs, and thus for gene expression. The bulk of pre-mRNAs are processed by canonical nuclear poly(A) polymerase (PAPS). Both vertebrate and higher-plant genomes encode more than one isoform of this enzyme, and these are coexpressed in different tissues. However, in neither case is it known whether the isoforms fulfill different functions or polyadenylate distinct subsets of pre-mRNAs. Here we show that the three canonical nuclear PAPS isoforms in Arabidopsis are functionally specialized owing to their evolutionarily divergent C-terminal domains. A strong loss-of-function mutation in PAPS1 causes a male gametophytic defect, whereas a weak allele leads to reduced leaf growth that results in part from a constitutive pathogen response. By contrast, plants lacking both PAPS2 and PAPS4 function are viable with wild-type leaf growth. Polyadenylation of SMALL AUXIN UP RNA (SAUR) mRNAs depends specifically on PAPS1 function. The resulting reduction in SAUR activity in paps1 mutants contributes to their reduced leaf growth, providing a causal link between polyadenylation of specific pre-mRNAs by a particular PAPS isoform and plant growth. This suggests the existence of an additional layer of regulation in plant and possibly vertebrate gene expression, whereby the relative activities of canonical nuclear PAPS isoforms control de novo synthesized poly(A) tail length and hence expression of specific subsets of mRNAs.
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25
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Barckmann B, Simonelig M. Control of maternal mRNA stability in germ cells and early embryos. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2013; 1829:714-24. [PMID: 23298642 DOI: 10.1016/j.bbagrm.2012.12.011] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2012] [Revised: 12/21/2012] [Accepted: 12/28/2012] [Indexed: 10/27/2022]
Abstract
mRNA regulation is essential in germ cells and early embryos. In particular, late oogenesis and early embryogenesis occur in the absence of transcription and rely on maternal mRNAs stored in oocytes. These maternal mRNAs subsequently undergo a general decay in embryos during the maternal-to-zygotic transition in which the control of development switches from the maternal to the zygotic genome. Regulation of mRNA stability thus plays a key role during these early stages of development and is tightly interconnected with translational regulation and mRNA localization. A common mechanism in these three types of regulation implicates variations in mRNA poly(A) tail length. Recent advances in the control of mRNA stability include the widespread and essential role of regulated deadenylation in early developmental processes, as well as the mechanisms regulating mRNA stability which involve RNA binding proteins, microRNAs and interplay between the two. Also emerging are the roles that other classes of small non-coding RNAs, endo-siRNAs and piRNAs play in the control of mRNA decay, including connections between the regulation of transposable elements and cellular mRNA regulation through the piRNA pathway. This article is part of a Special Issue entitled: RNA Decay mechanisms.
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Affiliation(s)
- Bridlin Barckmann
- mRNA Regulation and Development, Institute of Human Genetics, Montpellier Cedex 5, France
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26
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Abstract
Egg activation is the final transition that an oocyte goes through to become a developmentally competent egg. This transition is usually triggered by a calcium-based signal that is often, but not always, initiated by fertilization. Activation encompasses a number of changes within the egg. These include changes to the egg's membranes and outer coverings to prevent polyspermy and to support the developing embryo, as well as resumption and completion of the meiotic cell cycle, mRNA polyadenylation, translation of new proteins, and the degradation of specific maternal mRNAs and proteins. The transition from an arrested, highly differentiated cell, the oocyte, to a developmentally active, totipotent cell, the activated egg or embryo, represents a complete change in cellular state. This is accomplished by altering ion concentrations and by widespread changes in both the proteome and the suite of mRNAs present in the cell. Here, we review the role of calcium and zinc in the events of egg activation, and the importance of macromolecular changes during this transition. The latter include the degradation and translation of proteins, protein posttranslational regulation through phosphorylation, and the degradation, of maternal mRNAs.
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Affiliation(s)
- Amber R Krauchunas
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, USA
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27
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Kallehauge TB, Robert MC, Bertrand E, Jensen TH. Nuclear retention prevents premature cytoplasmic appearance of mRNA. Mol Cell 2012; 48:145-52. [PMID: 22921936 DOI: 10.1016/j.molcel.2012.07.022] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Revised: 07/02/2012] [Accepted: 07/17/2012] [Indexed: 10/28/2022]
Abstract
In S. cerevisiae cells debilitated in mRNA nuclear export, transcripts are retained in nuclear foci ("dots"). The ultimate fate of dot-mRNA has remained elusive. Here, we use single molecule counting microscopy and (35)S-methionine pulse-labeling assays to quantify cytoplasmic HSP104 RNA levels and estimate HSP104 RNA translation status. HSP104 transcripts, retained in dots as a consequence of the mex67-5 mutation, are slowly released over time for cytoplasmic translation. Thus, dot-mRNA retains function. However, forcing its nuclear export, by overexpressing the Sub2p mRNA export factor, does not elevate Hsp104p protein levels but is instead paralleled by growth deficiency. Nuclear export and growth phenotypes are both counteracted by coexpressing the nuclear RNA quality control factor Rrp6p. Thus, prematurely released dot-mRNA is translationally inactive and possibly toxic. Accordingly, nuclear retention of mRNA may serve a precautionary role during stressful situations such as, e.g., decreased mRNA maturation competence.
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Affiliation(s)
- Thomas Beuchert Kallehauge
- Department of Molecular Biology and Genetics, Centre for mRNP Biogenesis and Metabolism, Aarhus University, Aarhus C, Denmark
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Kelly S, Pak C, Garshasbi M, Kuss A, Corbett AH, Moberg K. New kid on the ID block: neural functions of the Nab2/ZC3H14 class of Cys₃His tandem zinc-finger polyadenosine RNA binding proteins. RNA Biol 2012; 9:555-62. [PMID: 22614829 DOI: 10.4161/rna.20187] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Polyadenosine RNA binding proteins (Pabs) play critical roles in regulating the polyadenylation, nuclear export, stability, and translation of cellular RNAs. Although most Pabs are ubiquitously expressed and are thought to play general roles in post-transcriptional regulation, mutations in genes encoding these factors have been linked to tissue-specific diseases including muscular dystrophy and now intellectual disability (ID). Our recent work defined this connection to ID, as we showed that mutations in the gene encoding the ubiquitously expressed Cys3His tandem zinc-finger (ZnF) Pab, ZC3H14 (Zinc finger protein, CCCH-type, number 14) are associated with non-syndromic autosomal recessive intellectual disability (NS-ARID). This study provided a first link between defects in Pab function and a brain disorder, suggesting that ZC3H14 plays a required role in regulating RNAs in nervous system cells. Here we highlight key questions raised by our study of ZC3H14 and its ortholog in the fruit fly Drosophila melanogaster, dNab2, and comment on future approaches that could provide insights into the cellular and molecular roles of this class of zinc finger-containing Pabs. We propose a summary model depicting how ZC3H14-type Pabs might play particularly important roles in neuronal RNA metabolism.
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Affiliation(s)
- Seth Kelly
- Emory University School of Medicine, 615 Michael Street, Atlanta, GA 30322, United States
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Minasaki R, Eckmann CR. Subcellular specialization of multifaceted 3'end modifying nucleotidyltransferases. Curr Opin Cell Biol 2012; 24:314-22. [PMID: 22551970 DOI: 10.1016/j.ceb.2012.03.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Revised: 03/24/2012] [Accepted: 03/29/2012] [Indexed: 10/28/2022]
Abstract
While canonical 3'end modifications of mRNAs or tRNAs are well established, recent technological advances in RNA analysis have given us a glimpse of how widespread other types of distinctive 3'end modifications appear to be. Next to alternative nuclear or cytoplasmic polyadenylation mechanisms, evidence accumulated for a variety of 3'end mono-nucleotide and oligo-nucleotide additions of primarily adenosines or uracils on a variety of RNA species. Enzymes responsible for such non-templated additions are non-canonical RNA nucleotidyltransferases, which possess surprising flexibility in RNA substrate selection and enzymatic activity. We will highlight recent findings supporting the view that RNA nucleotidyltransferase activity, RNA target selection and sub-compartimentalization are spatially, temporally and physiologically regulated by dedicated co-factors. Along with the diversification of non-coding RNA classes, the evolutionary conservation of these multifaceted RNA modifiers underscores the prevalence and importance of diverse 3'end formation mechanisms.
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Affiliation(s)
- Ryuji Minasaki
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
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Fukaya T, Tomari Y. PABP is not essential for microRNA-mediated translational repression and deadenylation in vitro. EMBO J 2011; 30:4998-5009. [PMID: 22117217 DOI: 10.1038/emboj.2011.426] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Accepted: 11/07/2011] [Indexed: 12/31/2022] Open
Abstract
MicroRNAs silence their complementary target genes via formation of the RNA-induced silencing complex (RISC) that contains an Argonaute (Ago) protein at its core. It was previously proposed that GW182, an Ago-associating protein, directly binds to poly(A)-binding protein (PABP) and interferes with its function, leading to silencing of the target mRNAs. Here we show that Drosophila Ago1-RISC induces silencing via two independent pathways: shortening of the poly(A) tail and pure repression of translation. Our data suggest that although PABP generally modulates poly(A) length and translation efficiency, neither PABP function nor GW182-PABP interaction is a prerequisite for these two silencing pathways. Instead, we propose that each of the multiple functional domains within GW182 has a potential for silencing, and yet they need to act together in the context of full-length GW182 to exert maximal silencing.
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Affiliation(s)
- Takashi Fukaya
- Institute of Molecular and Cellular Biosciences, University of Tokyo, Bunkyo-ku, Tokyo, Japan
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31
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Igreja C, Izaurralde E. CUP promotes deadenylation and inhibits decapping of mRNA targets. Genes Dev 2011; 25:1955-67. [PMID: 21937713 DOI: 10.1101/gad.17136311] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
CUP is an eIF4E-binding protein (4E-BP) that represses the expression of specific maternal mRNAs prior to their posterior localization. Here, we show that CUP employs multiple mechanisms to repress the expression of target mRNAs. In addition to inducing translational repression, CUP maintains mRNA targets in a repressed state by promoting their deadenylation and protects deadenylated mRNAs from further degradation. Translational repression and deadenylation are independent of eIF4E binding and require both the middle and C-terminal regions of CUP, which collectively we termed the effector domain. This domain associates with the deadenylase complex CAF1-CCR4-NOT and decapping activators. Accordingly, in isolation, the effector domain is a potent trigger of mRNA degradation and promotes deadenylation, decapping and decay. However, in the context of the full-length CUP protein, the decapping and decay mediated by the effector domain are inhibited, and target mRNAs are maintained in a deadenylated, repressed form. Remarkably, an N-terminal regulatory domain containing a noncanonical eIF4E-binding motif is required to protect CUP-associated mRNAs from decapping and further degradation, suggesting that this domain counteracts the activity of the effector domain. Our findings indicate that the mode of action of CUP is more complex than previously thought and provide mechanistic insight into the regulation of mRNA expression by 4E-BPs.
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Affiliation(s)
- Catia Igreja
- Max Planck Institute for Developmental Biology, Tübingen, Germany
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32
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Abstract
Translational control of specific mRNAs is a widespread mechanism of gene regulation, and it is especially important in pattern formation in the oocytes of organisms in which the embryonic axes are established maternally. Drosophila and Xenopus have been especially valuable in elucidating the relevant molecular mechanisms. Here, we comprehensively review what is known about translational control in these two systems, focusing on examples that illustrate key concepts that have emerged. We focus on protein-mediated translational control, rather than regulation mediated by small RNAs, as the former appears to be predominant in controlling these developmental events. Mechanisms that modulate the ability of the specific mRNAs to be recruited to the ribosome, that regulate polyadenylation of specific mRNAs, or that control the association of particular mRNAs into translationally inert ribonucleoprotein complexes will all be discussed.
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Affiliation(s)
- Joel D Richter
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01606, USA.
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Mutation of the conserved polyadenosine RNA binding protein, ZC3H14/dNab2, impairs neural function in Drosophila and humans. Proc Natl Acad Sci U S A 2011; 108:12390-5. [PMID: 21734151 DOI: 10.1073/pnas.1107103108] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Here we report a human intellectual disability disease locus on chromosome 14q31.3 corresponding to mutation of the ZC3H14 gene that encodes a conserved polyadenosine RNA binding protein. We identify ZC3H14 mRNA transcripts in the human central nervous system, and we find that rodent ZC3H14 protein is expressed in hippocampal neurons and colocalizes with poly(A) RNA in neuronal cell bodies. A Drosophila melanogaster model of this disease created by mutation of the gene encoding the ZC3H14 ortholog dNab2, which also binds polyadenosine RNA, reveals that dNab2 is essential for development and required in neurons for normal locomotion and flight. Biochemical and genetic data indicate that dNab2 restricts bulk poly(A) tail length in vivo, suggesting that this function may underlie its role in development and disease. These studies reveal a conserved requirement for ZC3H14/dNab2 in the metazoan nervous system and identify a poly(A) RNA binding protein associated with a human brain disorder.
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Eckmann CR, Rammelt C, Wahle E. Control of poly(A) tail length. WILEY INTERDISCIPLINARY REVIEWS-RNA 2010; 2:348-61. [PMID: 21957022 DOI: 10.1002/wrna.56] [Citation(s) in RCA: 191] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Poly(A) tails have long been known as stable 3' modifications of eukaryotic mRNAs, added during nuclear pre-mRNA processing. It is now appreciated that this modification is much more diverse: A whole new family of poly(A) polymerases has been discovered, and poly(A) tails occur as transient destabilizing additions to a wide range of different RNA substrates. We review the field from the perspective of poly(A) tail length. Length control is important because (1) poly(A) tail shortening from a defined starting point acts as a timer of mRNA stability, (2) changes in poly(A) tail length are used for the purpose of translational regulation, and (3) length may be the key feature distinguishing between the stabilizing poly(A) tails of mRNAs and the destabilizing oligo(A) tails of different unstable RNAs. The mechanism of length control during nuclear processing of pre-mRNAs is relatively well understood and is based on the changes in the processivity of poly(A) polymerase induced by two RNA-binding proteins. Developmentally regulated poly(A) tail extension also generates defined tails; however, although many of the proteins responsible are known, the reaction is not understood mechanistically. Finally, destabilizing oligoadenylation does not appear to have inherent length control. Rather, average tail length results from the balance between polyadenylation and deadenylation.
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Affiliation(s)
- Christian R Eckmann
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Dresden, Germany
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Maternal mRNA deadenylation and decay by the piRNA pathway in the early Drosophila embryo. Nature 2010; 467:1128-32. [PMID: 20953170 DOI: 10.1038/nature09465] [Citation(s) in RCA: 328] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2010] [Accepted: 08/27/2010] [Indexed: 12/25/2022]
Abstract
Piwi-associated RNAs (piRNAs), a specific class of 24- to 30-nucleotide-long RNAs produced by the Piwi-type of Argonaute proteins, have a specific germline function in repressing transposable elements. This repression is thought to involve heterochromatin formation and transcriptional and post-transcriptional silencing. The piRNA pathway has other essential functions in germline stem cell maintenance and in maintaining germline DNA integrity. Here we uncover an unexpected function of the piRNA pathway in the decay of maternal messenger RNAs and in translational repression in the early embryo. A subset of maternal mRNAs is degraded in the embryo at the maternal-to-zygotic transition. In Drosophila, maternal mRNA degradation depends on the RNA-binding protein Smaug and the deadenylase CCR4, as well as the zygotic expression of a microRNA cluster. Using mRNA encoding the embryonic posterior morphogen Nanos (Nos) as a paradigm to study maternal mRNA decay, we found that CCR4-mediated deadenylation of nos depends on components of the piRNA pathway including piRNAs complementary to a specific region in the nos 3' untranslated region. Reduced deadenylation when piRNA-induced regulation is impaired correlates with nos mRNA stabilization and translational derepression in the embryo, resulting in head development defects. Aubergine, one of the Argonaute proteins in the piRNA pathway, is present in a complex with Smaug, CCR4, nos mRNA and piRNAs that target the nos 3' untranslated region, in the bulk of the embryo. We propose that piRNAs and their associated proteins act together with Smaug to recruit the CCR4 deadenylation complex to specific mRNAs, thus promoting their decay. Because the piRNAs involved in this regulation are produced from transposable elements, this identifies a direct developmental function for transposable elements in the regulation of gene expression.
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36
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Shepherd A, Wesley U, Wesley C. Notch and delta mRNAs in early-stage and mid-stage drosophila embryos exhibit complementary patterns of protein-producing potentials. Dev Dyn 2010; 239:1220-33. [PMID: 20201103 DOI: 10.1002/dvdy.22262] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Notch and Delta proteins generate Notch signaling that specifies cell fates during animal development. There is an intriguing phenomenon in Drosophila embryogenesis that has not received much attention and whose significance to embryogenesis is unknown. Notch and Delta mRNAs expressed in early-stage embryos are shorter than their counterparts in mid-stage embryos. We show here that the difference in sizes is due to mRNA 3' processing at alternate polyadenylation sites. While the early-stage Notch mRNA has a lower protein-producing potential than the mid-stage Notch mRNA, the early-stage Delta mRNA has a higher protein-producing potential than the mid-stage Delta mRNA. Our data can explain the complementary patterns of Notch and Delta protein levels in early- and mid-stage embryos. Our data also raise the possibility that the manner and regulation of Notch signaling change in the course of embryogenesis and that this change is effected by 3' UTR and mRNA 3' processing factors.
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Affiliation(s)
- Andrew Shepherd
- Department of Biology, University of Vermont, Burlington, Vermont 05405, USA
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37
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Coll O, Villalba A, Bussotti G, Notredame C, Gebauer F. A novel, noncanonical mechanism of cytoplasmic polyadenylation operates in Drosophila embryogenesis. Genes Dev 2010; 24:129-34. [PMID: 20080951 DOI: 10.1101/gad.568610] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Cytoplasmic polyadenylation is a widespread mechanism to regulate mRNA translation that requires two sequences in the 3' untranslated region (UTR) of vertebrate substrates: the polyadenylation hexanucleotide, and the cytoplasmic polyadenylation element (CPE). Using a cell-free Drosophila system, we show that these signals are not relevant for Toll polyadenylation but, instead, a "polyadenylation region" (PR) is necessary. Competition experiments indicate that PR-mediated polyadenylation is required for viability and is mechanistically distinct from the CPE/hexanucleotide-mediated process. These data indicate that Toll mRNA is polyadenylated by a noncanonical mechanism, and suggest that a novel machinery functions for cytoplasmic polyadenylation during Drosophila embryogenesis.
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Affiliation(s)
- Olga Coll
- Gene Regulation Programme, Centre de Regulació Genòmica (CRG-UPF), 08003 Barcelona, Spain
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38
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Shepherd AK, Singh R, Wesley CS. Notch mRNA expression in Drosophila embryos is negatively regulated at the level of mRNA 3' processing. PLoS One 2009; 4:e8063. [PMID: 19956683 PMCID: PMC2778129 DOI: 10.1371/journal.pone.0008063] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2009] [Accepted: 10/30/2009] [Indexed: 12/24/2022] Open
Abstract
Notch receptor regulates differentiation of almost all tissues and organs during animal development. Many mechanisms function at the protein level to finely regulate Notch activity. Here we provide evidence for Notch regulation at an earlier step - mRNA 3′ processing. Processing at the Notch consensus polyadenylation site appears by default to be suppressed in Drosophila embryos. Interference with this suppression, by a mutation, results in increased levels of polyadenylated Notch mRNA, excess Notch signaling, and severe developmental defects. We propose that Notch mRNA 3′ processing is negatively regulated to limit the production of Notch protein and render it a controlling factor in the generation of Notch signaling.
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Affiliation(s)
- Andrew K. Shepherd
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont, United States of America
| | - Ravinder Singh
- Department of Molecular, Cell and Developmental Biology, University of Colorado, Boulder, Colorado, United States of America
| | - Cedric S. Wesley
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont, United States of America
- * E-mail:
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Translational control during early development. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2009; 90:211-54. [PMID: 20374743 DOI: 10.1016/s1877-1173(09)90006-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Translational control of specific messenger RNAs, which themselves are often asymmetrically localized within the cytoplasm of a cell, underlies many events in germline development, and in embryonic axis specification. This comprehensive, but by no means exhaustive, review attempts to present a picture of the present state of knowledge about mechanisms underlying mRNA localization and translational control of specific mRNAs that are mediated by trans-acting protein factors. While RNA localization and translational control are widespread in evolution and have been studied in many experimental systems, this article will focus mainly on three particularly well-characterized systems: Drosophila, Caenorhabditis elegans, and Xenopus. In keeping with the overall theme of this volume, instances in which translational control factors have been linked to human disease states will also be discussed.
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40
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Zhang DX, Cui XS, Kim NH. Involvement of polyadenylation status on maternal gene expression during in vitro maturation of porcine oocytes. Mol Reprod Dev 2009; 76:881-9. [PMID: 19479986 DOI: 10.1002/mrd.21056] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
During mammalian oocyte maturation, protein synthesis is mainly controlled through cytoplasmic polyadenylation of stored maternal mRNAs. In this study, the role of polyadenylation modification of maternal transcripts in pig oocytes was investigated by adding cordycepin (3'-dA), a potent polyadenylation inhibitor, to the culture medium of porcine oocytes maturing in vitro. 3'-dA significantly prevented cumulus expansion regardless of the concentration used, and inhibited pig oocyte maturation in a dose-dependent manner. Further, 3'-dA 1 microg/ml-treated MII oocytes experienced significantly lower rates of cleavage (29%) and blastocyst formation (15.35%) compared to control MII oocytes (58.6% and 35.3%, respectively). Western blotting revealed that the activity of mitogen-activated protein kinase (MAPK) and p34(cdc2) was significantly decreased in oocytes and cumulus cells treated with 3'-dA at a concentration of 1 microg/ml or greater. To further explore the underlying molecular mechanisms, expression patterns and polyadenylation states of four important genes, C-mos, cyclin B, GDF9 and BMP15, were studied as representative maternal transcripts by real-time PCR and the PAT assay. 3'-dA at concentrations above 1 microg/ml significantly prevented polyadenylation and caused aberrant expression of C-mos and GDF9 during oocyte maturation. These results suggest that polyadenylation inhibitor blocked pig oocyte maturation in vitro by one or more of the following actions: (1) inactivation of MAPK and MPF in oocytes, especially at the late stages (MI and MII); (2) prevention of cumulus cell expansion through inactivation of cellular MAPK; and (3) inhibition of the maternal mRNA polyadenylation process, which in reverse, disrupted the maternal mRNA patterns in pig oocytes' maturation in vitro.
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Affiliation(s)
- Ding-Xiao Zhang
- Department of Animal Sciences, Chungbuk National University, Cheongju, Chungbuk 361-763 Korea, Cheongju, 361-763 South Korea
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41
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Rangan P, DeGennaro M, Jaime-Bustamante K, Coux RX, Martinho RG, Lehmann R. Temporal and spatial control of germ-plasm RNAs. Curr Biol 2008; 19:72-7. [PMID: 19110432 PMCID: PMC2766415 DOI: 10.1016/j.cub.2008.11.066] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2008] [Revised: 11/24/2008] [Accepted: 11/26/2008] [Indexed: 12/19/2022]
Abstract
In many species, germ cells form in a specialized germ plasm, which contains localized maternal RNAs. In the absence of active transcription in early germ cells, these maternal RNAs encode germ-cell components with critical functions in germ-cell specification, migration, and development. For several RNAs, localization has been correlated with release from translational repression, suggesting an important regulatory function linked to localization. To address the role of RNA localization and translational control more systematically, we assembled a comprehensive set of RNAs that are localized to polar granules, the characteristic germ-plasm organelles. We find that the 3'-untranslated regions (UTRs) of all RNAs tested control RNA localization and instruct distinct temporal patterns of translation of the localized RNAs. We demonstrate necessity for translational timing by swapping the 3'UTR of polar granule component (pgc), which controls translation in germ cells, with that of nanos, which is translated earlier. Translational activation of pgc is concurrent with extension of its poly(A) tail length but appears largely independent of the Drosophila CPEB homolog ORB. Our results demonstrate a role for 3'UTR mediated translational regulation in fine-tuning the temporal expression of localized RNA, and this may provide a paradigm for other RNAs that are found enriched at distinct cellular locations such as the leading edge of fibroblasts or the neuronal synapse.
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Affiliation(s)
- Prashanth Rangan
- HHMI and Kimmel Center for Biology and Medicine of the Skirball Institute, Department of Cell Biology, New York University School of Medicine, New York, NY 10016, USA
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Transcriptional state and distribution of poly(A) RNA and RNA polymerase II in differentiating Hyacinthus orientalis L. pollen grains. ACTA ACUST UNITED AC 2008. [DOI: 10.1007/s00497-008-0085-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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43
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Kwak JE, Drier E, Barbee SA, Ramaswami M, Yin JCP, Wickens M. GLD2 poly(A) polymerase is required for long-term memory. Proc Natl Acad Sci U S A 2008; 105:14644-9. [PMID: 18780789 PMCID: PMC2567210 DOI: 10.1073/pnas.0803185105] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2008] [Indexed: 01/17/2023] Open
Abstract
The formation of long-term memory is believed to require translational control of localized mRNAs. In mammals, dendritic mRNAs are maintained in a repressed state and are activated upon repetitive stimulation. Several regulatory proteins required for translational control in early development are thought to be required for memory formation, suggesting similar molecular mechanisms. Here, using Drosophila, we identify the enzyme responsible for poly(A) elongation in the brain and demonstrate that its activity is required specifically for long-term memory. These findings provide strong evidence that cytoplasmic polyadenylation is critical for memory formation, and that GLD2 is the enzyme responsible.
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Affiliation(s)
| | - Eric Drier
- Genetics, and Psychiatry, Waisman Center, University of Wisconsin, Madison, WI 53706
| | - Scott A. Barbee
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721; and
| | - Mani Ramaswami
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721; and
- Smurfit Institute of Genetics and Trinity College Institute for Neuroscience,Trinity College, Dublin 2, Ireland
| | - Jerry C. P. Yin
- Genetics, and Psychiatry, Waisman Center, University of Wisconsin, Madison, WI 53706
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44
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BENOIT P, PAPIN C, KWAK JE, WICKENS M, SIMONELIG M. PAP- and GLD-2-type poly(A) polymerases are required sequentially in cytoplasmic polyadenylation and oogenesis in Drosophila. Development 2008; 135:1969-79. [PMID: 18434412 PMCID: PMC9154023 DOI: 10.1242/dev.021444] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Cytoplasmic polyadenylation has an essential role in activating maternal mRNA translation during early development. In vertebrates, the reaction requires CPEB, an RNA-binding protein and the poly(A) polymerase GLD-2. GLD-2-type poly(A) polymerases form a family clearly distinguishable from canonical poly(A) polymerases (PAPs). In Drosophila, canonical PAP is involved in cytoplasmic polyadenylation with Orb, the Drosophila CPEB, during mid-oogenesis. We show that the female germline GLD-2 is encoded by wispy. Wispy acts as a poly(A) polymerase in a tethering assay and in vivo for cytoplasmic polyadenylation of specific mRNA targets during late oogenesis and early embryogenesis. wispy function is required at the final stage of oogenesis for metaphase of meiosis I arrest and for progression beyond this stage. By contrast, canonical PAP acts with Orb for the earliest steps of oogenesis. Both Wispy and PAP interact with Orb genetically and physically in an ovarian complex. We conclude that two distinct poly(A) polymerases have a role in cytoplasmic polyadenylation in the female germline, each of them being specifically required for different steps of oogenesis.
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Affiliation(s)
- Perrine BENOIT
- mRNA Regulation and Development, Institut de Génétique Humaine, CNRS UPR 1142, 141 rue de la Cardonille, 34396 Montpellier Cedex 5, France
| | - Catherine PAPIN
- mRNA Regulation and Development, Institut de Génétique Humaine, CNRS UPR 1142, 141 rue de la Cardonille, 34396 Montpellier Cedex 5, France
| | - Jae Eun KWAK
- Department of Biochemistry, 433 Babcock Drive, University of Wisconsin, Madison, WI 53706 1544, USA
| | - Marvin WICKENS
- Department of Biochemistry, 433 Babcock Drive, University of Wisconsin, Madison, WI 53706 1544, USA
| | - Martine SIMONELIG
- mRNA Regulation and Development, Institut de Génétique Humaine, CNRS UPR 1142, 141 rue de la Cardonille, 34396 Montpellier Cedex 5, France
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45
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Translational control by cytoplasmic polyadenylation in Xenopus oocytes. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2008; 1779:217-29. [PMID: 18316045 PMCID: PMC2323027 DOI: 10.1016/j.bbagrm.2008.02.002] [Citation(s) in RCA: 155] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/21/2007] [Revised: 01/30/2008] [Accepted: 02/04/2008] [Indexed: 12/21/2022]
Abstract
Elongation of the poly(A) tails of specific mRNAs in the cytoplasm is a crucial regulatory step in oogenesis and early development of many animal species. The best studied example is the regulation of translation by cytoplasmic polyadenylation elements (CPEs) in the 3′ untranslated region of mRNAs involved in Xenopus oocyte maturation. In this review we discuss the mechanism of translational control by the CPE binding protein (CPEB) in Xenopus oocytes as follows:The cytoplasmic polyadenylation machinery such as CPEB, the subunits of cleavage and polyadenylation specificity factor (CPSF), symplekin, Gld-2 and poly(A) polymerase (PAP). The signal transduction that leads to the activation of CPE-mediated polyadenylation during oocyte maturation, including the potential roles of kinases such as MAPK, Aurora A, CamKII, cdk1/Ringo and cdk1/cyclin B. The role of deadenylation and translational repression, including the potential involvement of PARN, CCR4/NOT, maskin, pumilio, Xp54 (Ddx6, Rck), other P-body components and isoforms of the cap binding initiation factor eIF4E.
Finally we discuss some of the remaining questions regarding the mechanisms of translational regulation by cytoplasmic polyadenylation and give our view on where our knowledge is likely to be expanded in the near future.
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Chicoine J, Benoit P, Gamberi C, Paliouras M, Simonelig M, Lasko P. Bicaudal-C recruits CCR4-NOT deadenylase to target mRNAs and regulates oogenesis, cytoskeletal organization, and its own expression. Dev Cell 2008; 13:691-704. [PMID: 17981137 DOI: 10.1016/j.devcel.2007.10.002] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2007] [Revised: 08/07/2007] [Accepted: 10/04/2007] [Indexed: 11/16/2022]
Abstract
Bicaudal-C (Bic-C) encodes an RNA-binding protein required maternally for patterning the Drosophila embryo. We identified a set of mRNAs that associate with Bic-C in ovarian ribonucleoprotein complexes. These mRNAs are enriched for mRNAs that function in oogenesis and in cytoskeletal regulation, and include Bic-C RNA itself. Bic-C binds specific segments of the Bic-C 5' untranslated region and negatively regulates its own expression by binding directly to NOT3/5, a component of the CCR4 core deadenylase complex, thereby promoting deadenylation. Bic-C overexpression induces premature cytoplasmic-streaming, a posterior-group phenotype, defects in Oskar and Kinesin heavy chain:betaGal localization as well as dorsal-appendage defects. These phenotypes are largely reciprocal to those of Bic-C mutants, and they affect cellular processes that Bic-C-associated mRNAs are known, or predicted, to regulate. We conclude that Bic-C regulates expression of specific germline mRNAs by controlling their poly(A)-tail length.
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Affiliation(s)
- Jarred Chicoine
- Department of Biology and Developmental Biology Research Initiative, McGill University, 1205 Avenue Docteur Penfield, Montréal, Québec H3A 1B1, Canada
| | - Perrine Benoit
- mRNA Regulation and Development, Institut de Génétique Humaine, CNRS, 141 rue de la Cardonille, 34396 Montpellier Cedex 5, France
| | - Chiara Gamberi
- Department of Biology and Developmental Biology Research Initiative, McGill University, 1205 Avenue Docteur Penfield, Montréal, Québec H3A 1B1, Canada
| | - Miltiadis Paliouras
- Department of Biology and Developmental Biology Research Initiative, McGill University, 1205 Avenue Docteur Penfield, Montréal, Québec H3A 1B1, Canada
| | - Martine Simonelig
- mRNA Regulation and Development, Institut de Génétique Humaine, CNRS, 141 rue de la Cardonille, 34396 Montpellier Cedex 5, France
| | - Paul Lasko
- Department of Biology and Developmental Biology Research Initiative, McGill University, 1205 Avenue Docteur Penfield, Montréal, Québec H3A 1B1, Canada.
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Vardy L, Orr-Weaver TL. The Drosophila PNG kinase complex regulates the translation of cyclin B. Dev Cell 2007; 12:157-66. [PMID: 17199048 DOI: 10.1016/j.devcel.2006.10.017] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2005] [Revised: 07/07/2006] [Accepted: 10/19/2006] [Indexed: 11/15/2022]
Abstract
The Drosophila PAN GU (PNG) kinase complex regulates the developmental translation of cyclin B. cyclin B mRNA becomes unmasked during oogenesis independent of PNG activity, but PNG is required for translation from egg activation. We find that although polyadenylation of cyclin B augments translation, it is not essential, and a fully elongated poly(A) is not required for translation to proceed. In fact, changes in poly(A) tail length are not sufficient to account for PNG-mediated control of cyclin B translation and of the early embryonic cell cycles. We present evidence that PNG functions instead as an antagonist of PUMILIO-dependent translational repression. Our data argue that changes in poly(A) tail length are not a universal mechanism governing embryonic cell cycles, and that PNG-mediated derepression of translation is an important alternative mechanism in Drosophila.
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Affiliation(s)
- Leah Vardy
- Whitehead Institute, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
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48
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Tadros W, Goldman AL, Babak T, Menzies F, Vardy L, Orr-Weaver T, Hughes TR, Westwood JT, Smibert CA, Lipshitz HD. SMAUG is a major regulator of maternal mRNA destabilization in Drosophila and its translation is activated by the PAN GU kinase. Dev Cell 2007; 12:143-55. [PMID: 17199047 DOI: 10.1016/j.devcel.2006.10.005] [Citation(s) in RCA: 239] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2005] [Revised: 07/10/2006] [Accepted: 10/06/2006] [Indexed: 11/23/2022]
Abstract
In animals, egg activation triggers a cascade of posttranscriptional events that act on maternally synthesized RNAs. We show that, in Drosophila, the PAN GU (PNG) kinase sits near the top of this cascade, triggering translation of SMAUG (SMG), a multifunctional posttranscriptional regulator conserved from yeast to humans. Although PNG is required for cytoplasmic polyadenylation of smg mRNA, it regulates translation via mechanisms that are independent of its effects on the poly(A) tail. Analyses of mutants suggest that PNG relieves translational repression by PUMILIO (PUM) and one or more additional factors, which act in parallel through the smg mRNA's 3' untranslated region (UTR). Microarray-based gene expression profiling shows that SMG is a major regulator of maternal transcript destabilization. SMG-dependent mRNAs are enriched for gene ontology annotations for function in the cell cycle, suggesting a possible causal relationship between failure to eliminate these transcripts and the cell cycle defects in smg mutants.
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Affiliation(s)
- Wael Tadros
- Graduate Department of Molecular and Medical Genetics, University of Toronto, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada
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Morales J, Mulner-Lorillon O, Cosson B, Morin E, Bellé R, Bradham CA, Beane WS, Cormier P. Translational control genes in the sea urchin genome. Dev Biol 2006; 300:293-307. [PMID: 16959243 DOI: 10.1016/j.ydbio.2006.07.036] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2006] [Revised: 07/25/2006] [Accepted: 07/27/2006] [Indexed: 10/24/2022]
Abstract
Sea urchin eggs and early cleavage stage embryos provide an example of regulated gene expression at the level of translation. The availability of the sea urchin genome offers the opportunity to investigate the "translational control" toolkit of this model system. The annotation of the genome reveals that most of the factors implicated in translational control are encoded by nonredundant genes in echinoderm, an advantage for future functional studies. In this paper, we focus on translation factors that have been shown or suggested to play crucial role in cell cycle and development of sea urchin embryos. Addressing the cap-binding translational control, three closely related eIF4E genes (class I, II, III) are present, whereas its repressor 4E-BP and its activator eIF4G are both encoded by one gene. Analysis of the class III eIF4E proteins in various phyla shows an echinoderm-specific amino acid substitution. Furthermore, an interaction site between eIF4G and poly(A)-binding protein is uncovered in the sea urchin eIF4G proteins and is conserved in metazoan evolution. In silico screening of the sea urchin genome has uncovered potential new regulators of eIF4E sharing the common eIF4E recognition motif. Taking together, these data provide new insights regarding the strong requirement of cap-dependent translation following fertilization. The genome analysis gives insights on the complexity of eEF1B structure and motifs of functional relevance, involved in the translational control of gene expression at the level of elongation. Finally, because deregulation of translation process can lead to diseases and tumor formation in humans, the sea urchin orthologs of human genes implicated in human diseases and signaling pathways regulating translation were also discussed.
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Affiliation(s)
- Julia Morales
- Equipe Cycle Cellulaire et Développement, UMR 7150 CNRS/UPMC, Station Biologique 29680 Roscoff, France.
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Zaessinger S, Busseau I, Simonelig M. Oskar allows nanos mRNA translation in Drosophila embryos by preventing its deadenylation by Smaug/CCR4. Development 2006; 133:4573-83. [PMID: 17050620 DOI: 10.1242/dev.02649] [Citation(s) in RCA: 146] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Anteroposterior patterning of the Drosophila embryo depends on a gradient of Nanos protein arising from the posterior pole. This gradient results from both nanos mRNA translational repression in the bulk of the embryo and translational activation of nanos mRNA localized at the posterior pole. Two mechanisms of nanos translational repression have been described, at the initiation step and after this step. Here we identify a novel level of nanos translational control. We show that the Smaug protein bound to the nanos 3' UTR recruits the deadenylation complex CCR4-NOT, leading to rapid deadenylation and subsequent decay of nanos mRNA. Inhibition of deadenylation causes stabilization of nanos mRNA, ectopic synthesis of Nanos protein and head defects. Therefore, deadenylation is essential for both translational repression and decay of nanos mRNA. We further propose a mechanism for translational activation at the posterior pole. Translation of nanos mRNA at the posterior pole depends on oskar function. We show that Oskar prevents the rapid deadenylation of nanos mRNA by precluding its binding to Smaug, thus leading to its stabilization and translation. This study provides insights into molecular mechanisms of regulated deadenylation by specific proteins and demonstrates its importance in development.
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Affiliation(s)
- Sophie Zaessinger
- Génétique du Développement de la Drosophile, Institut de Génétique Humaine, CNRS UPR 1142, 141 rue de la Cardonille, 34396 Montpellier Cedex 5, France
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