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Joshi R, Sipani R, Bakshi A. Roles of Drosophila Hox Genes in the Assembly of Neuromuscular Networks and Behavior. Front Cell Dev Biol 2022; 9:786993. [PMID: 35071230 PMCID: PMC8777297 DOI: 10.3389/fcell.2021.786993] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 12/14/2021] [Indexed: 11/13/2022] Open
Abstract
Hox genes have been known for specifying the anterior-posterior axis (AP) in bilaterian body plans. Studies in vertebrates have shown their importance in developing region-specific neural circuitry and diversifying motor neuron pools. In Drosophila, they are instrumental for segment-specific neurogenesis and myogenesis early in development. Their robust expression in differentiated neurons implied their role in assembling region-specific neuromuscular networks. In the last decade, studies in Drosophila have unequivocally established that Hox genes go beyond their conventional functions of generating cellular diversity along the AP axis of the developing central nervous system. These roles range from establishing and maintaining the neuromuscular networks to controlling their function by regulating the motor neuron morphology and neurophysiology, thereby directly impacting the behavior. Here we summarize the limited knowledge on the role of Drosophila Hox genes in the assembly of region-specific neuromuscular networks and their effect on associated behavior.
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Affiliation(s)
- Rohit Joshi
- Laboratory of Drosophila Neural Development, Centre for DNA Fingerprinting and Diagnostics (CDFD), Hyderabad, India
| | - Rashmi Sipani
- Laboratory of Drosophila Neural Development, Centre for DNA Fingerprinting and Diagnostics (CDFD), Hyderabad, India.,Graduate Studies, Manipal Academy of Higher Education, Manipal, India
| | - Asif Bakshi
- Laboratory of Drosophila Neural Development, Centre for DNA Fingerprinting and Diagnostics (CDFD), Hyderabad, India.,Graduate Studies, Manipal Academy of Higher Education, Manipal, India
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2
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miRNAs and Neural Alternative Polyadenylation Specify the Virgin Behavioral State. Dev Cell 2020; 54:410-423.e4. [PMID: 32579967 DOI: 10.1016/j.devcel.2020.06.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 04/03/2020] [Accepted: 06/01/2020] [Indexed: 01/08/2023]
Abstract
How are diverse regulatory strategies integrated to impose appropriately patterned gene expression that underlie in vivo phenotypes? Here, we reveal how coordinated miRNA regulation and neural-specific alternative polyadenylation (APA) of a single locus controls complex behaviors. Our entry was the unexpected observation that deletion of Bithorax complex (BX-C) miRNAs converts virgin female flies into a subjective post-mated behavioral state, normally induced by seminal proteins following copulation. Strikingly, this behavioral switch is directly attributable to misregulation of homothorax (hth). We localize specific CNS abdominal neurons where de-repressed Hth compromises virgin behavior in BX-C miRNA mutants. Moreover, we use genome engineering to demonstrate that precise mutation of hth 3' UTR sites for BX-C miRNAs or deletion of its neural 3' UTR extension containing most of these sites both induce post-mated behaviors in virgins. Thus, facilitation of miRNA-mediated repression by neural APA is required for virgin females to execute behaviors appropriate to their internal state.
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3
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Markey FB, Parashar V, Batish M. Methods for spatial and temporal imaging of the different steps involved in RNA processing at single-molecule resolution. WILEY INTERDISCIPLINARY REVIEWS-RNA 2020; 12:e1608. [PMID: 32543077 DOI: 10.1002/wrna.1608] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2019] [Revised: 05/06/2020] [Accepted: 05/07/2020] [Indexed: 12/26/2022]
Abstract
RNA plays a quintessential role as a messenger of information from genotype (DNA) to phenotype (proteins), as well as acts as a regulatory molecule (noncoding RNAs). All steps in the journey of RNA from synthesis (transcription), splicing, transport, localization, translation, to its eventual degradation, comprise important steps in gene expression, thereby controlling the fate of the cell. This lifecycle refers to the majority of RNAs (primarily mRNAs), but not other RNAs such as tRNAs. Imaging these processes in fixed cells and in live cells has been an important tool in developing an understanding of the regulatory steps in RNAs journey. Single-cell and single-molecule imaging techniques enable a much deeper understanding of cellular biology, which is not possible with bulk studies involving RNA isolated from a large pool of cells. Classic techniques, such as fluorescence in situ hybridization (FISH), as well as more recent aptamer-based approaches, have provided detailed insights into RNA localization, and have helped to predict the functions carried out by many RNA species. However, there are still certain processing steps that await high-resolution imaging, which is an exciting and upcoming area of research. In this review, we will discuss the methods that have revolutionized single-molecule resolution imaging in general, the steps of RNA processing in which these methods have been used, and new emerging technologies. This article is categorized under: RNA Export and Localization > RNA Localization RNA Methods > RNA Analyses in Cells RNA Interactions with Proteins and Other Molecules > Small Molecule-RNA Interactions.
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Affiliation(s)
- Fatu Badiane Markey
- Department of Microbiology, Biochemistry and Molecular Genetics, New Jersey Medical School, Rutgers University, Newark, New Jersey, USA
| | - Vijay Parashar
- Department of Medical and Molecular Sciences, University of Delaware, Newark, Delaware, USA
| | - Mona Batish
- Department of Microbiology, Biochemistry and Molecular Genetics, New Jersey Medical School, Rutgers University, Newark, New Jersey, USA.,Department of Medical and Molecular Sciences, University of Delaware, Newark, Delaware, USA
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4
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Issa AR, Picao-Osorio J, Rito N, Chiappe ME, Alonso CR. A Single MicroRNA-Hox Gene Module Controls Equivalent Movements in Biomechanically Distinct Forms of Drosophila. Curr Biol 2019; 29:2665-2675.e4. [PMID: 31327720 PMCID: PMC6710004 DOI: 10.1016/j.cub.2019.06.082] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 06/18/2019] [Accepted: 06/27/2019] [Indexed: 12/19/2022]
Abstract
Movement is the main output of the nervous system. It emerges during development to become a highly coordinated physiological process essential to survival and adaptation of the organism to the environment. Similar movements can be observed in morphologically distinct developmental stages of an organism, but it is currently unclear whether or not these movements have a common molecular cellular basis. Here we explore this problem in Drosophila, focusing on the roles played by the microRNA (miRNA) locus miR-iab4/8, which we previously showed to be essential for the normal corrective response displayed by the fruit fly larva when turned upside down (self-righting). Our study shows that miR-iab4 is required for normal self-righting across all three Drosophila larval stages. Unexpectedly, we also discover that this miRNA is essential for normal self-righting behavior in the adult fly, an organism with different morphology, neural constitution, and biomechanics. Through the combination of gene expression, optical imaging, and quantitative behavioral approaches, we provide evidence that miR-iab4 exerts its effects on adult self-righting behavior in part through repression of the Hox gene Ultrabithorax (Ubx) in a specific set of adult motor neurons, the NB2-3/lin15 neurons. Our results show that miRNA controls the function, rather than the morphology, of these neurons and demonstrate that post-developmental changes in Hox gene expression can modulate behavior in the adult. Our work reveals that a common miRNA-Hox genetic module can be re-deployed in different neurons to control functionally equivalent movements in biomechanically distinct organisms and describes a novel post-developmental role of the Hox genes in adult neural function. The fruit fly miRNA gene miR-iab4 controls the same behavior in the larva and adult miR-iab4 exerts its behavioral roles via repression of the Hox gene Ultrabithorax miRNA/Hox inputs affect the physiology and not the anatomy of specific motor neurons Conditional expression shows a novel role of the Hox genes in adult neural function
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Affiliation(s)
- A Raouf Issa
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Biology Road, Brighton BN1 9QG, UK
| | - João Picao-Osorio
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Biology Road, Brighton BN1 9QG, UK
| | - Nuno Rito
- Champalimaud Neuroscience Programme, Champalimaud Center for the Unknown, Brasília Avenue, Doca de Pedrouços, 1400-038 Lisbon, Portugal
| | - M Eugenia Chiappe
- Champalimaud Neuroscience Programme, Champalimaud Center for the Unknown, Brasília Avenue, Doca de Pedrouços, 1400-038 Lisbon, Portugal
| | - Claudio R Alonso
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Biology Road, Brighton BN1 9QG, UK.
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5
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Kaschula R, Pinho S, Alonso CR. MicroRNA-dependent regulation of Hox gene expression sculpts fine-grain morphological patterns in a Drosophila appendage. Development 2018; 145:dev.161133. [PMID: 30143542 PMCID: PMC6215401 DOI: 10.1242/dev.161133] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Accepted: 08/06/2018] [Indexed: 11/26/2022]
Abstract
Disruptions of normal Hox gene expression can lead to severe morphological defects, revealing a link between the regulation of Hox expression and pattern formation. Here, we explore these links, focusing on the impact of microRNA regulation on the expression of the Drosophila Hox gene Ultrabithorax (Ubx) during haltere development. Through a combination of bioinformatic and transcriptomic analyses, we identify the miR-310/313 cluster (miR-310C) as a candidate regulator of Ubx. Several experiments confirm this. First, miR-310C and Ubx protein show complementary expression patterns in haltere imaginal discs; second, artificial activation of miR-310C expression in haltere discs leads to Ubx-like phenotypes. Third, expression of a fluorescent reporter bearing Ubx 3′UTR sequences is reduced when co-expressed with miR-310C. Fourth, deletion of miR-310C leads to Ubx upregulation and changes the array of mechanosensory sensilla at the base of the haltere. Fifth, an artificial increase of Ubx levels within the miR-310C expression domain phenocopies the mechanosensory defects observed in miR-310C mutants. We propose that miR-310C-mediated repression delimits Ubx fine-grain expression, contributing to the sculpting of complex morphologies in the Drosophila haltere with implications for flight control. Our work reveals a novel role of microRNA regulation in the control of Hox gene expression with impact on morphology. Summary: A novel role of microRNAs in the control of Hox gene expression with impact on the development of morphology in Drosophila, suggesting that microRNAs might play similar roles in other bilaterians.
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Affiliation(s)
- Richard Kaschula
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK
| | - Sofia Pinho
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK
| | - Claudio R Alonso
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK
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6
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Agarwal V, Subtelny AO, Thiru P, Ulitsky I, Bartel DP. Predicting microRNA targeting efficacy in Drosophila. Genome Biol 2018; 19:152. [PMID: 30286781 PMCID: PMC6172730 DOI: 10.1186/s13059-018-1504-3] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 08/06/2018] [Indexed: 12/17/2022] Open
Abstract
Background MicroRNAs (miRNAs) are short regulatory RNAs that derive from hairpin precursors. Important for understanding the functional roles of miRNAs is the ability to predict the messenger RNA (mRNA) targets most responsive to each miRNA. Progress towards developing quantitative models of miRNA targeting in Drosophila and other invertebrate species has lagged behind that of mammals due to the paucity of datasets measuring the effects of miRNAs on mRNA levels. Results We acquired datasets suitable for the quantitative study of miRNA targeting in Drosophila. Analyses of these data expanded the types of regulatory sites known to be effective in flies, expanded the mRNA regions with detectable targeting to include 5′ untranslated regions, and identified features of site context that correlate with targeting efficacy in fly cells. Updated evolutionary analyses evaluated the probability of conserved targeting for each predicted site and indicated that more than a third of the Drosophila genes are preferentially conserved targets of miRNAs. Based on these results, a quantitative model was developed to predict targeting efficacy in insects. This model performed better than existing models, and it drives the most recent version, v7, of TargetScanFly. Conclusions Our evolutionary and functional analyses expand the known scope of miRNA targeting in flies and other insects. The existence of a quantitative model that has been developed and trained using Drosophila data will provide a valuable resource for placing miRNAs into gene regulatory networks of this important experimental organism. Electronic supplementary material The online version of this article (10.1186/s13059-018-1504-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Vikram Agarwal
- Whitehead Institute for Biomedical Research and Howard Hughes Medical Institute, 9 Cambridge Center, Cambridge, MA, 02142, USA.,Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.,Computational and Systems Biology Program, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.,Present address: Department of Genome Sciences, University of Washington, Seattle, WA, 98195, USA
| | - Alexander O Subtelny
- Whitehead Institute for Biomedical Research and Howard Hughes Medical Institute, 9 Cambridge Center, Cambridge, MA, 02142, USA.,Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.,Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA, 02139, USA
| | - Prathapan Thiru
- Whitehead Institute for Biomedical Research and Howard Hughes Medical Institute, 9 Cambridge Center, Cambridge, MA, 02142, USA
| | - Igor Ulitsky
- Department of Biological Regulation, Weizmann Institute of Science, Rehovot 76100, Israel
| | - David P Bartel
- Whitehead Institute for Biomedical Research and Howard Hughes Medical Institute, 9 Cambridge Center, Cambridge, MA, 02142, USA. .,Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
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7
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Saka E, Harrison BJ, West K, Petruska JC, Rouchka EC. Framework for reanalysis of publicly available Affymetrix® GeneChip® data sets based on functional regions of interest. BMC Genomics 2017; 18:875. [PMID: 29244006 PMCID: PMC5731501 DOI: 10.1186/s12864-017-4266-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023] Open
Abstract
BACKGROUND Since the introduction of microarrays in 1995, researchers world-wide have used both commercial and custom-designed microarrays for understanding differential expression of transcribed genes. Public databases such as ArrayExpress and the Gene Expression Omnibus (GEO) have made millions of samples readily available. One main drawback to microarray data analysis involves the selection of probes to represent a specific transcript of interest, particularly in light of the fact that transcript-specific knowledge (notably alternative splicing) is dynamic in nature. RESULTS We therefore developed a framework for reannotating and reassigning probe groups for Affymetrix® GeneChip® technology based on functional regions of interest. This framework addresses three issues of Affymetrix® GeneChip® data analyses: removing nonspecific probes, updating probe target mapping based on the latest genome knowledge and grouping probes into gene, transcript and region-based (UTR, individual exon, CDS) probe sets. Updated gene and transcript probe sets provide more specific analysis results based on current genomic and transcriptomic knowledge. The framework selects unique probes, aligns them to gene annotations and generates a custom Chip Description File (CDF). The analysis reveals only 87% of the Affymetrix® GeneChip® HG-U133 Plus 2 probes uniquely align to the current hg38 human assembly without mismatches. We also tested new mappings on the publicly available data series using rat and human data from GSE48611 and GSE72551 obtained from GEO, and illustrate that functional grouping allows for the subtle detection of regions of interest likely to have phenotypical consequences. CONCLUSION Through reanalysis of the publicly available data series GSE48611 and GSE72551, we profiled the contribution of UTR and CDS regions to the gene expression levels globally. The comparison between region and gene based results indicated that the detected expressed genes by gene-based and region-based CDFs show high consistency and regions based results allows us to detection of changes in transcript formation.
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Affiliation(s)
- Ernur Saka
- Department of Computer Engineering and Computer Science, University of Louisville, Louisville, KY, USA
| | - Benjamin J Harrison
- Department of Anatomical Sciences and Neurobiology, School of Medicine University of Louisville, Louisville, KY, USA.,Department of Biological Sciences, University of New England, Biddeford, ME, USA
| | - Kirk West
- Department of Biochemistry and Molecular Biology University of Arkansas for Medical Science, Little Rock, AR, USA
| | - Jeffrey C Petruska
- Department of Anatomical Sciences and Neurobiology, School of Medicine University of Louisville, Louisville, KY, USA
| | - Eric C Rouchka
- Department of Computer Engineering and Computer Science, University of Louisville, Louisville, KY, USA.
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8
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Vallejos Baier R, Picao-Osorio J, Alonso CR. Molecular Regulation of Alternative Polyadenylation (APA) within the Drosophila Nervous System. J Mol Biol 2017; 429:3290-3300. [PMID: 28366829 PMCID: PMC5656104 DOI: 10.1016/j.jmb.2017.03.028] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 03/24/2017] [Accepted: 03/24/2017] [Indexed: 12/17/2022]
Abstract
Alternative polyadenylation (APA) is a widespread gene regulatory mechanism that generates mRNAs with different 3'-ends, allowing them to interact with different sets of RNA regulators such as microRNAs and RNA-binding proteins. Recent studies have shown that during development, neural tissues produce mRNAs with particularly long 3'UTRs, suggesting that such extensions might be important for neural development and function. Despite this, the mechanisms underlying neural APA are not well understood. Here, we investigate this problem within the Drosophila nervous system, focusing on the roles played by general cleavage and polyadenylation factors (CPA factors). In particular, we examine the model that modulations in CPA factor concentration may affect APA during development. For this, we first analyse the expression of the Drosophila orthologues of all mammalian CPA factors and note that their expression decreases during embryogenesis. In contrast to this global developmental decrease in CPA factor expression, we see that cleavage factor I (CFI) expression is actually elevated in the late embryonic central nervous system, suggesting that CFI might play a special role in neural tissues. To test this, we use the UAS/Gal4 system to deplete CFI proteins from neural tissue and observe that in this condition, multiple genes switch their APA patterns, demonstrating a role of CFI in APA control during Drosophila neural development. Furthermore, analysis of genes with 3'UTR extensions of different length leads us to suggest a novel relation between 3'UTR length and sensitivity to CPA factor expression. Our work thus contributes to the understanding of the mechanisms of APA control within the developing central nervous system.
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Affiliation(s)
- Raul Vallejos Baier
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK
| | - Joao Picao-Osorio
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK
| | - Claudio R Alonso
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK.
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9
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Pervasive Behavioral Effects of MicroRNA Regulation in Drosophila. Genetics 2017; 206:1535-1548. [PMID: 28468905 PMCID: PMC5500149 DOI: 10.1534/genetics.116.195776] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 04/23/2017] [Indexed: 11/18/2022] Open
Abstract
Picao-Osorio et al. reveal pervasive effects of microRNA regulation on complex locomotor behaviors in Drosophila larvae: over 40% of microRNAs display... The effects of microRNA (miRNA) regulation on the genetic programs underlying behavior remain largely unexplored. Despite this, recent work in Drosophila shows that mutation of a single miRNA locus (miR-iab4/iab8) affects the capacity of the larva to correct its orientation if turned upside down (self-righting, SR), suggesting that other miRNAs might also be involved in behavioral control. Here we explore this possibility, studying early larval SR behavior in a collection of 81 Drosophila miRNA mutants covering almost the entire miRNA complement of the late embryo. Unexpectedly, we observe that >40% of all miRNAs tested significantly affect SR time, revealing pervasive behavioral effects of miRNA regulation in the early larva. Detailed analyses of those miRNAs affecting SR behavior (SR-miRNAs) show that individual miRNAs can affect movement in different ways, suggesting that specific molecular and cellular elements are affected by individual miRNA mutations. Furthermore, gene expression analysis shows that the Hox gene Abdominal-B (Abd-B) represents one of the targets deregulated by several SR-miRNAs. Our work thus reveals pervasive effects of miRNA regulation on a complex innate behavior in Drosophila and suggests that miRNAs may be core components of the genetic programs underlying behavioral control in other animals too.
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10
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MicroRNA filters Hox temporal transcription noise to confer boundary formation in the spinal cord. Nat Commun 2017; 8:14685. [PMID: 28337978 PMCID: PMC5376671 DOI: 10.1038/ncomms14685] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Accepted: 01/24/2017] [Indexed: 01/17/2023] Open
Abstract
The initial rostrocaudal patterning of the neural tube leads to differential expression of Hox genes that contribute to the specification of motor neuron (MN) subtype identity. Although several 3' Hox mRNAs are expressed in progenitors in a noisy manner, these Hox proteins are not expressed in the progenitors and only become detectable in postmitotic MNs. MicroRNA biogenesis impairment leads to precocious expression and propagates the noise of Hoxa5 at the protein level, resulting in an imprecise Hoxa5-Hoxc8 boundary. Here we uncover, using in silico simulation, two feed-forward Hox-miRNA loops accounting for the precocious and noisy Hoxa5 expression, as well as an ill-defined boundary phenotype in Dicer mutants. Finally, we identify mir-27 as a major regulator coordinating the temporal delay and spatial boundary of Hox protein expression. Our results provide a novel trans Hox-miRNA circuit filtering transcription noise and controlling the timing of protein expression to confer robust individual MN identity.
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11
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Azlan A, Dzaki N, Azzam G. Argonaute: The executor of small RNA function. J Genet Genomics 2016; 43:481-94. [PMID: 27569398 DOI: 10.1016/j.jgg.2016.06.002] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 05/08/2016] [Accepted: 06/17/2016] [Indexed: 01/06/2023]
Abstract
The discovery of small non-coding RNAs - microRNA (miRNA), short interfering RNA (siRNA) and PIWI-interacting RNA (piRNA) - represents one of the most exciting frontiers in biology specifically on the mechanism of gene regulation. In order to execute their functions, these small RNAs require physical interactions with their protein partners, the Argonaute (AGO) family proteins. Over the years, numerous studies have made tremendous progress on understanding the roles of AGO in gene silencing in various organisms. In this review, we summarize recent progress of AGO-mediated gene silencing and other cellular processes in which AGO proteins have been implicated with a particular focus on progress made in flies, humans and other model organisms as compliment.
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Affiliation(s)
- Azali Azlan
- School of Biological Sciences, Universiti Sains Malaysia, Penang 11800, Malaysia
| | - Najat Dzaki
- School of Biological Sciences, Universiti Sains Malaysia, Penang 11800, Malaysia
| | - Ghows Azzam
- School of Biological Sciences, Universiti Sains Malaysia, Penang 11800, Malaysia; Advance Medical and Dental Institute, Universiti Sains Malaysia, Penang 11800, Malaysia.
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12
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Warnefors M, Hartmann B, Thomsen S, Alonso CR. Combinatorial Gene Regulatory Functions Underlie Ultraconserved Elements in Drosophila. Mol Biol Evol 2016; 33:2294-306. [PMID: 27247329 PMCID: PMC4989106 DOI: 10.1093/molbev/msw101] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Ultraconserved elements (UCEs) are discrete genomic elements conserved across large evolutionary distances. Although UCEs have been linked to multiple facets of mammalian gene regulation their extreme evolutionary conservation remains largely unexplained. Here, we apply a computational approach to investigate this question in Drosophila, exploring the molecular functions of more than 1,500 UCEs shared across the genomes of 12 Drosophila species. Our data indicate that Drosophila UCEs are hubs for gene regulatory functions and suggest that UCE sequence invariance originates from their combinatorial roles in gene control. We also note that the gene regulatory roles of intronic and intergenic UCEs (iUCEs) are distinct from those found in exonic UCEs (eUCEs). In iUCEs, transcription factor (TF) and epigenetic factor binding data strongly support iUCE roles in transcriptional and epigenetic regulation. In contrast, analyses of eUCEs indicate that they are two orders of magnitude more likely than the expected to simultaneously include protein-coding sequence, TF-binding sites, splice sites, and RNA editing sites but have reduced roles in transcriptional or epigenetic regulation. Furthermore, we use a Drosophila cell culture system and transgenic Drosophila embryos to validate the notion of UCE combinatorial regulatory roles using an eUCE within the Hox gene Ultrabithorax and show that its protein-coding region also contains alternative splicing regulatory information. Taken together our experiments indicate that UCEs emerge as a result of combinatorial gene regulatory roles and highlight common features in mammalian and insect UCEs implying that similar processes might underlie ultraconservation in diverse animal taxa.
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Affiliation(s)
- Maria Warnefors
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, United Kingdom Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Britta Hartmann
- Institute of Human Genetics, Freiburg, Germany BIOSS Centre for Biological Signaling Studies, University Medical Center Freiburg, Freiburg, Germany
| | - Stefan Thomsen
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - Claudio R Alonso
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, United Kingdom
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13
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Picao-Osorio J, Johnston J, Landgraf M, Berni J, Alonso CR. MicroRNA-encoded behavior in Drosophila. Science 2015; 350:815-20. [PMID: 26494171 PMCID: PMC4902127 DOI: 10.1126/science.aad0217] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 09/25/2015] [Indexed: 12/20/2022]
Abstract
The relationship between microRNA (miRNA) regulation and the specification of behavior is only beginning to be explored. We found that mutation of a single miRNA locus (miR-iab4/iab8) in Drosophila larvae affects the animal's capacity to correct its orientation if turned upside down (self-righting). One of the miRNA targets involved in this behavior is the Hox gene Ultrabithorax, whose derepression in two metameric neurons leads to self-righting defects. In vivo neural activity analysis reveals that these neurons, the self-righting node (SRN), have different activity patterns in wild type and miRNA mutants, whereas thermogenetic manipulation of SRN activity results in changes in self-righting behavior. Our work thus reveals a miRNA-encoded behavior and suggests that other miRNAs might also be involved in behavioral control in Drosophila and other species.
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Affiliation(s)
- Joao Picao-Osorio
- Sussex Neuroscience, School of Life Science, University of Sussex, Brighton BN1 9QG, UK
| | - Jamie Johnston
- Sussex Neuroscience, School of Life Science, University of Sussex, Brighton BN1 9QG, UK
| | - Matthias Landgraf
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
| | - Jimena Berni
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
| | - Claudio R Alonso
- Sussex Neuroscience, School of Life Science, University of Sussex, Brighton BN1 9QG, UK.
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14
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Hox miRNA regulation within the Drosophila Bithorax complex: Patterning behavior. Mech Dev 2015; 138 Pt 2:151-159. [PMID: 26311219 DOI: 10.1016/j.mod.2015.08.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Revised: 08/14/2015] [Accepted: 08/17/2015] [Indexed: 01/02/2023]
Abstract
The study of Drosophila Hox genes, located in the Antennapedia complex (ANT-C) and Bithorax complex (BX-C), has provided fundamental insights into mechanisms of how the segments of the animal body plan are specified. Notably, even though the analysis of the BX-C formally began over a century ago, surprises continue to emerge regarding its regulation and function. Even simply the gene content of the BX-C has been regularly revised in past years, especially with regard to non-coding RNAs (ncRNAs), including microRNAs. In this perspective, we review the history of studies of non-coding transcription in the BX-C, and highlight recent studies of its miRNAs that provide new insights into their tissue-specific roles in Hox gene regulation. In particular, we have demonstrated unexpected importance of endogenous BX-C miRNAs to restrict the spatial accumulation of Hox proteins and their TALE cofactors in the ventral nerve cord, and link this to aberrant neural differentiation and reproductive behavior. These findings open new directions on studying Hox miRNA function, and we speculate that further understanding of their roles in insect models may provide new leads for studying the enigmatic biological functions of analogous miRNAs located in vertebrate Hox clusters.
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15
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Moris-Sanz M, Estacio-Gómez A, Sánchez-Herrero E, Díaz-Benjumea FJ. The study of the Bithorax-complex genes in patterning CCAP neurons reveals a temporal control of neuronal differentiation by Abd-B. Biol Open 2015; 4:1132-42. [PMID: 26276099 PMCID: PMC4582124 DOI: 10.1242/bio.012872] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
During development, HOX genes play critical roles in the establishment of segmental differences. In the Drosophila central nervous system, these differences are manifested in the number and type of neurons generated by each neuroblast in each segment. HOX genes can act either in neuroblasts or in postmitotic cells, and either early or late in a lineage. Additionally, they can be continuously required during development or just at a specific stage. Moreover, these features are generally segment-specific. Lately, it has been shown that contrary to what happens in other tissues, where HOX genes define domains of expression, these genes are expressed in individual cells as part of the combinatorial codes involved in cell type specification. In this report we analyse the role of the Bithorax-complex genes - Ultrabithorax, abdominal-A and Abdominal-B - in sculpting the pattern of crustacean cardioactive peptide (CCAP)-expressing neurons. These neurons are widespread in invertebrates, express CCAP, Bursicon and MIP neuropeptides and play major roles in controlling ecdysis. There are two types of CCAP neuron: interneurons and efferent neurons. Our results indicate that Ultrabithorax and Abdominal-A are not necessary for specification of the CCAP-interneurons, but are absolutely required to prevent the death by apoptosis of the CCAP-efferent neurons. Furthermore, Abdominal-B controls by repression the temporal onset of neuropeptide expression in a subset of CCAP-efferent neurons, and a peak of ecdysone hormone at the end of larval life counteracts this repression. Thus, Bithorax complex genes control the developmental appearance of these neuropeptides both temporally and spatially.
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Affiliation(s)
- M Moris-Sanz
- Centro de Biología Molecular-Severo Ochoa (CSIC-UAM), c./Nicolás Cabrera 1, Universidad Autónoma, Madrid 28049, Spain
| | - A Estacio-Gómez
- Centro de Biología Molecular-Severo Ochoa (CSIC-UAM), c./Nicolás Cabrera 1, Universidad Autónoma, Madrid 28049, Spain
| | - E Sánchez-Herrero
- Centro de Biología Molecular-Severo Ochoa (CSIC-UAM), c./Nicolás Cabrera 1, Universidad Autónoma, Madrid 28049, Spain
| | - F J Díaz-Benjumea
- Centro de Biología Molecular-Severo Ochoa (CSIC-UAM), c./Nicolás Cabrera 1, Universidad Autónoma, Madrid 28049, Spain
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16
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Following the intracellular localization of the iab-8ncRNA of the bithorax complex using the MS2-MCP-GFP system. Mech Dev 2015; 138 Pt 2:133-140. [PMID: 26277563 DOI: 10.1016/j.mod.2015.08.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Revised: 08/05/2015] [Accepted: 08/07/2015] [Indexed: 10/23/2022]
Abstract
Homeotic genes are aligned on the chromosome in the order of the segments that they specify along the antero-posterior axis of the fly. In general the genes affecting the more posterior segments repress the more anterior genes, a phenomenon known as "posterior dominance". There is however a noticeable exception to this rule in the central nervous system of Drosophila melanogaster where the posterior Abd-B gene does not repress the immediately more anterior abd-A gene. Instead, abd-A repression is accomplished by a 92 kb-long ncRNA (the iab-8ncRNA) that is transcribed from the large inter-genic region between abd-A and Abd-B. This iab-8ncRNA encodes a microRNA to repress abd-A and also a second redundant repression mechanism acting in cis and thought to be transcriptional interference with the abd-A promoter. Using in situ hybridization, a previous work suggested that the iab8ncRNA transcript forms discrete foci restricted to the nuclear periphery and that this localization may be important for its function. In order to better characterize the intra-cellular localization of the iab-8ncRNA we used the MS2-MCP system, which allows fluorescent labeling of RNA in cells and relies on the interaction between GFP-tagged MS2 coat protein (MCP-GFP) and MS2 RNA stem loops. Our results indicate that the large foci seen in previous studies correspond to the site of iab8ncRNA transcription and that the foci seen may simply be an indication of the level of transcription at the locus. We find no evidence to suggest that this localization is important for its function on abd-A repression. We discuss the idea that the iab-8ncRNA may be a relic of a more general ancient mechanism of posterior dominance during the emergence of the hox clusters that was mediated by transcriptional interference.
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17
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Gene Model Annotations for Drosophila melanogaster: Impact of High-Throughput Data. G3-GENES GENOMES GENETICS 2015; 5:1721-36. [PMID: 26109357 PMCID: PMC4528329 DOI: 10.1534/g3.115.018929] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We report the current status of the FlyBase annotated gene set for Drosophila melanogaster and highlight improvements based on high-throughput data. The FlyBase annotated gene set consists entirely of manually annotated gene models, with the exception of some classes of small non-coding RNAs. All gene models have been reviewed using evidence from high-throughput datasets, primarily from the modENCODE project. These datasets include RNA-Seq coverage data, RNA-Seq junction data, transcription start site profiles, and translation stop-codon read-through predictions. New annotation guidelines were developed to take into account the use of the high-throughput data. We describe how this flood of new data was incorporated into thousands of new and revised annotations. FlyBase has adopted a philosophy of excluding low-confidence and low-frequency data from gene model annotations; we also do not attempt to represent all possible permutations for complex and modularly organized genes. This has allowed us to produce a high-confidence, manageable gene annotation dataset that is available at FlyBase (http://flybase.org). Interesting aspects of new annotations include new genes (coding, non-coding, and antisense), many genes with alternative transcripts with very long 3′ UTRs (up to 15–18 kb), and a stunning mismatch in the number of male-specific genes (approximately 13% of all annotated gene models) vs. female-specific genes (less than 1%). The number of identified pseudogenes and mutations in the sequenced strain also increased significantly. We discuss remaining challenges, for instance, identification of functional small polypeptides and detection of alternative translation starts.
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18
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Jin Y, Geisberg JV, Moqtaderi Z, Ji Z, Hoque M, Tian B, Struhl K. Mapping 3' mRNA isoforms on a genomic scale. ACTA ACUST UNITED AC 2015; 110:4.23.1-4.23.17. [PMID: 25827089 DOI: 10.1002/0471142727.mb0423s110] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Most eukaryotic genes are transcribed into mRNAs with alternative poly(A) sites. Emerging evidence suggests that mRNA isoforms with alternative poly(A) sites can perform critical regulatory functions in numerous biological processes. In recent years, a number of strategies utilizing high-throughput sequencing technologies have been developed to aid in the identification of genome-wide poly(A) sites. This unit describes a modified protocol for a recently published 3'READS (3' region extraction and deep sequencing) method that accurately identifies genome-wide poly(A) sites and that can be used to quantify the relative abundance of the resulting 3' mRNA isoforms. This approach minimizes nonspecific sequence reads due to internal priming and typically yields a high percentage of sequence reads that are ideally suited for accurate poly(A) identification.
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Affiliation(s)
- Yi Jin
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts
| | - Joseph V Geisberg
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts
| | - Zarmik Moqtaderi
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts
| | - Zhe Ji
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts
| | - Mainul Hoque
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School, Newark, New Jersey
| | - Bin Tian
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School, Newark, New Jersey
| | - Kevin Struhl
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts
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19
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Moreira A. Integrating transcription kinetics with alternative polyadenylation and cell cycle control. Nucleus 2014; 2:556-61. [DOI: 10.4161/nucl.2.6.18064] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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20
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Ichinose J, Watanabe K, Sano A, Nagase T, Nakajima J, Fukayama M, Yatomi Y, Ohishi N, Takai D. Alternative polyadenylation is associated with lower expression of PABPN1 and poor prognosis in non-small cell lung cancer. Cancer Sci 2014; 105:1135-41. [PMID: 24975429 PMCID: PMC4462401 DOI: 10.1111/cas.12472] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 06/16/2014] [Accepted: 06/24/2014] [Indexed: 12/22/2022] Open
Abstract
Alternative polyadenylation (APA), which induces shortening of the 3′UTR, is emerging as an important phenomenon in gene regulation. APA is involved in development, cancer and cell proliferation. APA may lead to disruption of microRNA-mediated gene silencing in cancer cells via detachment of microRNA binding sites. We studied the correlation between the APA profile and the tumor aggressiveness in cases of lung cancer. We selected the top 10 genes showing significant 3′UTR shortening in lung cancer, using the package of the Bioconductor for probe-level analyses of expression microarrays. We established and evaluated the APA score by quantitative RT-PCR in 147 clinical specimens of non-small cell lung cancer and compared the results with the clinical outcomes and expression levels of APA-related genes, including PABPN1, CPEB1, E2F1 and proliferation markers (MKI67, TOP2A and MCM2). High APA scores were correlated with an advanced tumor stage and a poor prognosis (P < 0.001). Multivariate analysis identified the APA score as an independent prognostic factor (hazard ratio, 3.0; P = 0.03). Both lower expression of PABPN1 and higher expression of the proliferation markers were correlated with high APA scores and a poor prognosis, with suppression of PABPN1 exerting its influence independent of gain of the proliferation markers. Moreover, the APA score was correlated with the maximum standardized uptake value of the tumors on positron emission tomography (r = 0.53; P < 0.001). Our results indicate that the loss of PABPN1, a suppressor of APA, might promote tumor aggressiveness by releasing the cancer cells from microRNA-mediated gene regulation.
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Affiliation(s)
- Junji Ichinose
- Department of Thoracic Surgery, University of Tokyo Hospital, Tokyo, Japan
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21
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Miura P, Sanfilippo P, Shenker S, Lai EC. Alternative polyadenylation in the nervous system: to what lengths will 3' UTR extensions take us? Bioessays 2014; 36:766-77. [PMID: 24903459 PMCID: PMC4503322 DOI: 10.1002/bies.201300174] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Alternative cleavage and polyadenylation (APA) can diversify coding and non-coding regions, but has particular impact on increasing 3' UTR diversity. Through the gain or loss of regulatory elements such as RNA binding protein and microRNA sites, APA can influence transcript stability, localization, and translational efficiency. Strikingly, the central nervous systems of invertebrate and vertebrate species express a broad range of transcript isoforms bearing extended 3' UTRs. The molecular mechanism that permits proximal 3' end bypass in neurons is mysterious, and only beginning to be elucidated. This landscape of neural 3' UTR extensions, many reaching unprecedented lengths, may help service the unique post-transcriptional regulatory needs of neurons. A combination of approaches, including transcriptome-wide profiling, genetic screening to identify APA factors, biochemical dissection of alternative 3' end formation, and manipulation of individual neural APA targets, will be necessary to gain fuller perspectives on the mechanism and biology of neural-specific 3' UTR lengthening.
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Affiliation(s)
- Pedro Miura
- Department of Developmental Biology, Sloan-Kettering Institute, 1275 York Ave, Box 252, New York NY 10065
| | - Piero Sanfilippo
- Department of Developmental Biology, Sloan-Kettering Institute, 1275 York Ave, Box 252, New York NY 10065
- Louis V. Gerstner, Jr. Graduate School of Biomedical Sciences, Memorial Sloan Kettering Cancer Center
| | - Sol Shenker
- Department of Developmental Biology, Sloan-Kettering Institute, 1275 York Ave, Box 252, New York NY 10065
- Tri-Institutional Program in Computational Biology and Medicine, Weill Cornell Medical College
| | - Eric C. Lai
- Department of Developmental Biology, Sloan-Kettering Institute, 1275 York Ave, Box 252, New York NY 10065
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22
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Rogulja-Ortmann A, Picao-Osorio J, Villava C, Patraquim P, Lafuente E, Aspden J, Thomsen S, Technau GM, Alonso CR. The RNA-binding protein ELAV regulates Hox RNA processing, expression and function within the Drosophila nervous system. Development 2014; 141:2046-56. [PMID: 24803653 PMCID: PMC4132933 DOI: 10.1242/dev.101519] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The regulated head-to-tail expression of Hox genes provides a coordinate system for the activation of specific programmes of cell differentiation according to axial level. Recent work indicates that Hox expression can be regulated via RNA processing but the underlying mechanisms and biological significance of this form of regulation remain poorly understood. Here we explore these issues within the developing Drosophila central nervous system (CNS). We show that the pan-neural RNA-binding protein (RBP) ELAV (Hu antigen) regulates the RNA processing patterns of the Hox gene Ultrabithorax (Ubx) within the embryonic CNS. Using a combination of biochemical, genetic and imaging approaches we demonstrate that ELAV binds to discrete elements within Ubx RNAs and that its genetic removal reduces Ubx protein expression in the CNS leading to the respecification of cellular subroutines under Ubx control, thus defining for the first time a specific cellular role of ELAV within the developing CNS. Artificial provision of ELAV in glial cells (a cell type that lacks ELAV) promotes Ubx expression, suggesting that ELAV-dependent regulation might contribute to cell type-specific Hox expression patterns within the CNS. Finally, we note that expression of abdominal A and Abdominal B is reduced in elav mutant embryos, whereas other Hox genes (Antennapedia) are not affected. Based on these results and the evolutionary conservation of ELAV and Hox genes we propose that the modulation of Hox RNA processing by ELAV serves to adapt the morphogenesis of the CNS to axial level by regulating Hox expression and consequently activating local programmes of neural differentiation.
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23
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Garaulet DL, Castellanos MC, Bejarano F, Sanfilippo P, Tyler DM, Allan DW, Sánchez-Herrero E, Lai EC. Homeotic function of Drosophila Bithorax-complex miRNAs mediates fertility by restricting multiple Hox genes and TALE cofactors in the CNS. Dev Cell 2014; 29:635-48. [PMID: 24909902 PMCID: PMC4111139 DOI: 10.1016/j.devcel.2014.04.023] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Revised: 02/20/2014] [Accepted: 04/21/2014] [Indexed: 02/07/2023]
Abstract
The Drosophila Bithorax complex (BX-C) Hox cluster contains a bidirectionally transcribed miRNA locus, and a deletion mutant (Δmir) lays no eggs and is completely sterile. We show these miRNAs are expressed and active in distinct spatial registers along the anterior-posterior axis in the CNS. Δmir larvae derepress a network of direct homeobox gene targets in the posterior ventral nerve cord (VNC), including BX-C genes and their TALE cofactors. These are phenotypically critical targets, because sterility of Δmir mutants was substantially rescued by heterozygosity of these genes. The posterior VNC contains Ilp7+ oviduct motoneurons, whose innervation and morphology are defective in Δmir females, and substantially rescued by heterozygosity of Δmir targets, especially within the BX-C. Collectively, we reveal (1) critical roles for Hox miRNAs that determine segment-specific expression of homeotic genes, which are not masked by transcriptional regulation; and (2) that BX-C miRNAs are essential for neural patterning and reproductive behavior.
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Affiliation(s)
- Daniel L Garaulet
- Department of Developmental Biology, Sloan-Kettering Institute, 1275 York Avenue, Box 252, New York, NY 10065, USA; Centro de Biología Molecular Severo Ochoa (C.S.I.C.-U.A.M.), Universidad Autónoma de Madrid, Nicolás Cabrera 1, Cantoblanco, 28049 Madrid, Spain
| | - Monica C Castellanos
- 2401 Life Sciences Centre, 2350 Health Sciences Mall, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Fernando Bejarano
- Department of Developmental Biology, Sloan-Kettering Institute, 1275 York Avenue, Box 252, New York, NY 10065, USA
| | - Piero Sanfilippo
- Department of Developmental Biology, Sloan-Kettering Institute, 1275 York Avenue, Box 252, New York, NY 10065, USA; Gerstner Sloan-Kettering Graduate School of Biomedical Sciences, 417 East 68th Street, New York, NY 10065, USA
| | - David M Tyler
- Department of Developmental Biology, Sloan-Kettering Institute, 1275 York Avenue, Box 252, New York, NY 10065, USA
| | - Douglas W Allan
- 2401 Life Sciences Centre, 2350 Health Sciences Mall, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Ernesto Sánchez-Herrero
- Centro de Biología Molecular Severo Ochoa (C.S.I.C.-U.A.M.), Universidad Autónoma de Madrid, Nicolás Cabrera 1, Cantoblanco, 28049 Madrid, Spain.
| | - Eric C Lai
- Department of Developmental Biology, Sloan-Kettering Institute, 1275 York Avenue, Box 252, New York, NY 10065, USA.
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24
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Gummalla M, Galetti S, Maeda RK, Karch F. Hox gene regulation in the central nervous system of Drosophila. Front Cell Neurosci 2014; 8:96. [PMID: 24795565 PMCID: PMC4005941 DOI: 10.3389/fncel.2014.00096] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Accepted: 03/14/2014] [Indexed: 12/20/2022] Open
Abstract
Hox genes specify the structures that form along the anteroposterior (AP) axis of bilateria. Within the genome, they often form clusters where, remarkably enough, their position within the clusters reflects the relative positions of the structures they specify along the AP axis. This correspondence between genomic organization and gene expression pattern has been conserved through evolution and provides a unique opportunity to study how chromosomal context affects gene regulation. In Drosophila, a general rule, often called “posterior dominance,” states that Hox genes specifying more posterior structures repress the expression of more anterior Hox genes. This rule explains the apparent spatial complementarity of Hox gene expression patterns in Drosophila. Here we review a noticeable exception to this rule where the more-posteriorly expressed Abd-B Hox gene fails to repress the more-anterior abd-A gene in cells of the central nervous system (CNS). While Abd-B is required to repress ectopic expression of abd-A in the posterior epidermis, abd-A repression in the posterior CNS is accomplished by a different mechanism that involves a large 92 kb long non-coding RNA (lncRNA) encoded by the intergenic region separating abd-A and Abd-B (the iab8ncRNA). Dissection of this lncRNA revealed that abd-A is repressed by the lncRNA using two redundant mechanisms. The first mechanism is mediated by a microRNA (mir-iab-8) encoded by intronic sequence within the large iab8-ncRNA. Meanwhile, the second mechanism seems to involve transcriptional interference by the long iab-8 ncRNA on the abd-A promoter. Recent work demonstrating CNS-specific regulation of genes by ncRNAs in Drosophila, seem to highlight a potential role for the iab-8-ncRNA in the evolution of the Drosophila Hox complexes.
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Affiliation(s)
- Maheshwar Gummalla
- Department of Genetics and Evolution, University of Geneva Geneva, Switzerland ; Institute of Biochemistry, University of Medicine - University of Göttingen Göttingen, Germany
| | - Sandrine Galetti
- Department of Genetics and Evolution, University of Geneva Geneva, Switzerland
| | - Robert K Maeda
- Department of Genetics and Evolution, University of Geneva Geneva, Switzerland
| | - François Karch
- Department of Genetics and Evolution, University of Geneva Geneva, Switzerland
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25
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Manipulation of RNA Using Engineered Proteins with Customized Specificity. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 825:199-225. [DOI: 10.1007/978-1-4939-1221-6_6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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26
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Mallo M, Alonso CR. The regulation of Hox gene expression during animal development. Development 2013; 140:3951-63. [PMID: 24046316 DOI: 10.1242/dev.068346] [Citation(s) in RCA: 223] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Hox genes encode a family of transcriptional regulators that elicit distinct developmental programmes along the head-to-tail axis of animals. The specific regional functions of individual Hox genes largely reflect their restricted expression patterns, the disruption of which can lead to developmental defects and disease. Here, we examine the spectrum of molecular mechanisms controlling Hox gene expression in model vertebrates and invertebrates and find that a diverse range of mechanisms, including nuclear dynamics, RNA processing, microRNA and translational regulation, all concur to control Hox gene outputs. We propose that this complex multi-tiered regulation might contribute to the robustness of Hox expression during development.
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Affiliation(s)
- Moisés Mallo
- Instituto Gulbenkian de Ciência, Rua da Quinta Grande 6, 2780-156 Oeiras, Portugal
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27
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Wang Y, Wang Z, Tanaka Hall TM. Engineered proteins with Pumilio/fem-3 mRNA binding factor scaffold to manipulate RNA metabolism. FEBS J 2013; 280:3755-67. [PMID: 23731364 DOI: 10.1111/febs.12367] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Revised: 05/29/2013] [Accepted: 05/30/2013] [Indexed: 01/13/2023]
Abstract
Pumilio/fem-3 mRNA binding factor proteins are characterized by a sequence-specific RNA-binding domain. This unique single-stranded RNA recognition module, whose sequence specificity can be reprogrammed, has been fused with functional modules to engineer protein factors with various functions. We summarize the advances made with respect to developing RNA regulatory tools, as well as opportunities for the future.
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Affiliation(s)
- Yang Wang
- Department of Pharmacology, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
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28
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Asgari S. MicroRNA functions in insects. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2013; 43:388-97. [PMID: 23103375 DOI: 10.1016/j.ibmb.2012.10.005] [Citation(s) in RCA: 184] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Revised: 10/11/2012] [Accepted: 10/16/2012] [Indexed: 05/14/2023]
Abstract
MicroRNAs (miRNAs) are small non-coding RNAs that are generated in all eukaryotes and viruses. Their role as master regulators of gene expression in various biological processes has only been fully appreciated over the last decade. Accumulating evidence suggests that alterations in the expression of miRNAs may lead to disorders, including developmental defects, diseases and cancer. Here, I review what is currently known about miRNA functions in insects to provide an insight into their diverse roles in insect biology.
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Affiliation(s)
- Sassan Asgari
- School of Biological Sciences, The University of Queensland, Brisbane, St Lucia, QLD 4072, Australia.
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29
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Azzam G, Liu JL. Only one isoform of Drosophila melanogaster CTP synthase forms the cytoophidium. PLoS Genet 2013; 9:e1003256. [PMID: 23459760 PMCID: PMC3573105 DOI: 10.1371/journal.pgen.1003256] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Accepted: 12/04/2012] [Indexed: 11/18/2022] Open
Abstract
CTP synthase is an essential enzyme that plays a key role in energy metabolism. Several independent studies have demonstrated that CTP synthase can form an evolutionarily conserved subcellular structure termed cytoophidium. In budding yeast, there are two isoforms of CTP synthase and both isoforms localize in cytoophidium. However, little is known about the distribution of CTP synthase isoforms in Drosophila melanogaster. Here, we report that three transcripts generated at the CTP synthase gene locus exhibit different expression profiles, and three isoforms encoded by this gene locus show a distinct subcellular distribution. While isoform A localizes in the nucleus, isoform B distributes diffusely in the cytoplasm, and only isoform C forms the cytoophidium. In the two isoform C-specific mutants, cytoophidia disappear in the germline cells. Although isoform A does not localize to the cytoophidium, a mutation disrupting mostly isoform A expression results in the disassembly of cytoophidia. Overexpression of isoform C can induce the growth of the cytoophidium in a cell-autonomous manner. Ectopic expression of the cytoophidium-forming isoform does not cause any defect in the embryos. In addition, we identify that a small segment at the amino terminus of isoform C is necessary but not sufficient for cytoophidium formation. Finally, we demonstrate that an excess of the synthetase domain of CTP synthase disrupts cytoophidium formation. Thus, the study of multiple isoforms of CTP synthase in Drosophila provides a good opportunity to dissect the biogenesis and function of the cytoophidum in a genetically tractable organism. DNA and RNA are made up from basic building blocks called nucleotides. Those nucleotides also play essential roles in many other biological processes. To separate biological processes within a cell is an important feature of all cell types. For example, mitochondria are specialized structures that contain ATP synthase, the enzyme that makes the nucleotide ATP. While mitochondria and ATP synthase have been studied for about 100 years, it was only very recently that we realized that there are specialized subcellular structures that contain CTP synthase, the enzyme that makes up another basic nucleotide CTP. Several independent studies have shown that CTP synthase molecules can form a filamentous structure called the cytoophidium (meaning “cellular snake” in Greek) or CTP synthase filament in bacteria, budding yeasts, fruit flies, and rat and human cells. In budding yeast, there are two isoforms of CTP synthase and both isoforms localize in the cytoophidium. Here, we report that three CTP synthase isoforms in fruit flies show a distinct subcellular distribution and only one isoform forms the cytoophidium. Thus, the study of multiple isoforms of CTP synthase in the fruit fly gives us a good way to begin to learn how and why CTP synthase molecules form this snake-like structure.
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Affiliation(s)
- Ghows Azzam
- Medical Research Council Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Ji-Long Liu
- Medical Research Council Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
- * E-mail:
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30
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Pang RT, Leung CO, Lee CL, Lam KK, Ye TM, Chiu PC, Yeung WS. MicroRNA-34a is a tumor suppressor in choriocarcinoma via regulation of Delta-like1. BMC Cancer 2013; 13:25. [PMID: 23327670 PMCID: PMC3561246 DOI: 10.1186/1471-2407-13-25] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Accepted: 01/10/2013] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Choriocarcinoma is a gestational trophoblastic tumor which causes high mortality if left untreated. MicroRNAs (miRNAs) are small non protein-coding RNAs which inhibit target gene expression. The role of miRNAs in choriocarcinoma, however, is not well understood. In this study, we examined the effect of miR-34a in choriocarcinoma. METHODS MiR-34a was either inhibited or ectopically expressed transiently in two choriocarcinoma cell lines (BeWo and JEG-3) respectively. Its actions on cell invasion, proliferation and colony formation at low cell density were examined. The miR-34a putative target Notch ligand Delta-like 1 (DLL1) was identified by adoption of different approaches including: in-silico analysis, functional luciferase assay and western blotting. Real-time quantitative polymerase chain reaction was used to quantify changes in the expression of matrix proteinase in the treated cells. To nullify the effect of miR-34a ectopic expression, we activated Notch signaling through force-expression of the Notch intracellular domain in the miR-34a force-expressed cells. In addition, we studied the importance of DLL1 in BeWo cell invasion through ligand stimulation and antibody inhibition. Furthermore, the induction in tumor formation of miR-34a-inhibited BeWo cells in SCID mice was investigated. RESULTS Transient miR-34a force-expression significantly suppressed cell proliferation and invasion in BeWo and JEG-3 cells. In silicon miRNA target prediction, luciferase functional assays and Western blotting analysis demonstrated that miR-34a regulated DLL1 expression in both cell lines. Although force-expression of miR-34a suppressed the expression of DLL1 and NOTCH1, the extent of suppression was higher in DLL1 than NOTCH1 in both cell lines. MiR-34a-mediated DLL1 suppression led to reduced matrix metallopeptidase 9 and urokinase-type plasminogen activator expression. The effect of miR-34a on cell invasion was partially nullified by Notch signaling activation. DLL1 ligand stimulated while anti-DLL1 antibody treatment suppressed cell invasion. Mice inoculated with BeWo cells transfected with miR-34a inhibitor had significantly larger xenografts and stronger DLL1 expression than those with cells transfected with the control inhibitor. CONCLUSIONS MiR-34a reduced cell proliferation and invasiveness, at least, partially through its inhibitory effect on DLL1.
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Affiliation(s)
- Ronald Tk Pang
- Department of Obstetrics and Gynaecology, The University of Hong Kong, Pokfulam Road, Hong Kong, China
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31
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Hui JHL, Marco A, Hunt S, Melling J, Griffiths-Jones S, Ronshaugen M. Structure, evolution and function of the bi-directionally transcribed iab-4/iab-8 microRNA locus in arthropods. Nucleic Acids Res 2013; 41:3352-61. [PMID: 23335784 PMCID: PMC3597655 DOI: 10.1093/nar/gks1445] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
In Drosophila melanogaster, the iab-4/iab-8 locus encodes bi-directionally transcribed microRNAs that regulate the function of flanking Hox transcription factors. We show that bi-directional transcription, temporal and spatial expression patterns and Hox regulatory function of the iab-4/iab-8 locus are conserved between fly and the beetle Tribolium castaneum. Computational predictions suggest iab-4 and iab-8 microRNAs can target common sites, and cell-culture assays confirm that iab-4 and iab-8 function overlaps on Hox target sites in both fly and beetle. However, we observe key differences in the way Hox genes are targeted. For instance, abd-A transcripts are targeted only by iab-8 in Drosophila, whereas both iab-4 and iab-8 bind to Tribolium abd-A. Our evolutionary and functional characterization of a bi-directionally transcribed microRNA establishes the iab-4/iab-8 system as a model for understanding how multiple products from sense and antisense microRNAs target common sites.
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Affiliation(s)
- Jerome H L Hui
- School of Life Sciences, Chinese University of Hong Kong, Shatin, Hong Kong, China
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32
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Wilkening S, Pelechano V, Järvelin AI, Tekkedil MM, Anders S, Benes V, Steinmetz LM. An efficient method for genome-wide polyadenylation site mapping and RNA quantification. Nucleic Acids Res 2013; 41:e65. [PMID: 23295673 PMCID: PMC3597643 DOI: 10.1093/nar/gks1249] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The use of alternative poly(A) sites is common and affects the post-transcriptional fate of mRNA, including its stability, subcellular localization and translation. Here, we present a method to identify poly(A) sites in a genome-wide and strand-specific manner. This method, termed 3′T-fill, initially fills in the poly(A) stretch with unlabeled dTTPs, allowing sequencing to start directly after the poly(A) tail into the 3′-untranslated regions (UTR). Our comparative analysis demonstrates that it outperforms existing protocols in quality and throughput and accurately quantifies RNA levels as only one read is produced from each transcript. We use this method to characterize the diversity of polyadenylation in Saccharomyces cerevisiae, showing that alternative RNA molecules are present even in a genetically identical cell population. Finally, we observe that overlap of convergent 3′-UTRs is frequent but sharply limited by coding regions, suggesting factors that restrict compression of the yeast genome.
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Affiliation(s)
- Stefan Wilkening
- Genome Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
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33
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Rehfeld A, Plass M, Krogh A, Friis-Hansen L. Alterations in polyadenylation and its implications for endocrine disease. Front Endocrinol (Lausanne) 2013; 4:53. [PMID: 23658553 PMCID: PMC3647115 DOI: 10.3389/fendo.2013.00053] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Accepted: 04/22/2013] [Indexed: 12/17/2022] Open
Abstract
INTRODUCTION Polyadenylation is the process in which the pre-mRNA is cleaved at the poly(A) site and a poly(A) tail is added - a process necessary for normal mRNA formation. Genes with multiple poly(A) sites can undergo alternative polyadenylation (APA), producing distinct mRNA isoforms with different 3' untranslated regions (3' UTRs) and in some cases different coding regions. Two thirds of all human genes undergo APA. The efficiency of the polyadenylation process regulates gene expression and APA plays an important part in post-transcriptional regulation, as the 3' UTR contains various cis-elements associated with post-transcriptional regulation, such as target sites for micro-RNAs and RNA-binding proteins. Implications of alterations in polyadenylation for endocrine disease: Alterations in polyadenylation have been found to be causative of neonatal diabetes and IPEX (immune dysfunction, polyendocrinopathy, enteropathy, X-linked) and to be associated with type I and II diabetes, pre-eclampsia, fragile X-associated premature ovarian insufficiency, ectopic Cushing syndrome, and many cancer diseases, including several types of endocrine tumor diseases. PERSPECTIVES Recent developments in high-throughput sequencing have made it possible to characterize polyadenylation genome-wide. Antisense elements inhibiting or enhancing specific poly(A) site usage can induce desired alterations in polyadenylation, and thus hold the promise of new therapeutic approaches. SUMMARY This review gives a detailed description of alterations in polyadenylation in endocrine disease, an overview of the current literature on polyadenylation and summarizes the clinical implications of the current state of research in this field.
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Affiliation(s)
- Anders Rehfeld
- Genomic Medicine, Rigshospitalet, Copenhagen University HospitalCopenhagen, Denmark
| | - Mireya Plass
- Department of Biology, The Bioinformatics Centre, University of CopenhagenCopenhagen, Denmark
| | - Anders Krogh
- Department of Biology, The Bioinformatics Centre, University of CopenhagenCopenhagen, Denmark
| | - Lennart Friis-Hansen
- Genomic Medicine, Rigshospitalet, Copenhagen University HospitalCopenhagen, Denmark
- *Correspondence: Lennart Friis-Hansen, Genomic Medicine, Rigshospitalet, Copenhagen University Hospital, 4113, Blegdamsvej 9, DK2100 Copenhagen, Denmark. e-mail:
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34
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Abstract
During development, it is essential for gene expression to occur in a very precise spatial and temporal manner. There are many levels at which regulation of gene expression can occur, and recent evidence demonstrates the importance of mRNA stability in governing the amount of mRNA that can be translated into functional protein. One of the most important discoveries in this field has been miRNAs (microRNAs) and their function in targeting specific mRNAs for repression. The wing imaginal discs of Drosophila are an excellent model system to study the roles of miRNAs during development and illustrate their importance in gene regulation. This review aims at discussing the developmental processes where control of gene expression by miRNAs is required, together with the known mechanisms of this regulation. These developmental processes include Hox gene regulation, developmental timing, growth control, specification of SOPs (sensory organ precursors) and the regulation of signalling pathways.
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Abstract
Since the last common ancestor of Metazoa, animals have evolved complex body plans with specialized cells and spatial organization of tissues and organs. Arguably, one of the most significant innovations during animal evolutionary history was the establishment of a bilateral plane of symmetry on which morphological features (e.g. tissues, organs, appendages, skeleton) could be given specific coordinates within the animal along the anterior-posterior (A-P) and dorsal-ventral (D-V) axes. Hox genes are a known group of eumetazoan transcription factors central to regulating A-P patterning, but less well known and under current investigation is the broader regulatory landscape incorporating these genes, including microRNA (miRNA) regulation. The degree to which evolutionarily conserved targeting of Hox genes by Hox-embedded miRNAs contributes directly to A-P patterning is under investigation, yielding contrasting information dependent on the organism and miRNA of interest. The widespread A-P patterning defects observed in recent miR-196 loss-of-function studies solidifies the importance of miRNA regulation in Hox genetic hierarchies, and elucidating the developmental and evolutionary importance of all Hox-embedded miRNAs remains a challenge for the future.
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Affiliation(s)
- Alysha Heimberg
- EMBL Australia, Australian Regenerative Medicine Institute, Monash University, Wellington Road, Clayton, 3800, Australia
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36
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Sun Y, Fu Y, Li Y, Xu A. Genome-wide alternative polyadenylation in animals: insights from high-throughput technologies. J Mol Cell Biol 2012; 4:352-61. [DOI: 10.1093/jmcb/mjs041] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
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37
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Li Y, Sun Y, Fu Y, Li M, Huang G, Zhang C, Liang J, Huang S, Shen G, Yuan S, Chen L, Chen S, Xu A. Dynamic landscape of tandem 3' UTRs during zebrafish development. Genome Res 2012; 22:1899-906. [PMID: 22955139 PMCID: PMC3460185 DOI: 10.1101/gr.128488.111] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Tandem 3' untranslated regions (UTRs), produced by alternative polyadenylation (APA) in the terminal exon of a gene, could have critical roles in regulating gene networks. Here we profiled tandem poly(A) events on a genome-wide scale during the embryonic development of zebrafish (Danio rerio) using a recently developed SAPAS method. We showed that 43% of the expressed protein-coding genes have tandem 3' UTRs. The average 3' UTR length follows a V-shaped dynamic pattern during early embryogenesis, in which the 3' UTRs are first shortened at zygotic genome activation, and then quickly lengthened during gastrulation. Over 4000 genes are found to switch tandem APA sites, and the distinct functional roles of these genes are indicated by Gene Ontology analysis. Three families of cis-elements, including miR-430 seed, U-rich element, and canonical poly(A) signal, are enriched in 3' UTR-shortened/lengthened genes in a stage-specific manner, suggesting temporal regulation coordinated by APA and trans-acting factors. Our results highlight the regulatory role of tandem 3' UTR control in early embryogenesis and suggest that APA may represent a new epigenetic paradigm of physiological regulations.
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Affiliation(s)
- Yuxin Li
- State Key Laboratory of Biocontrol, National Engineering Center of South China Sea for Marine Biotechnology, Guangdong Province Key Laboratory of Pharmaceutical Functional Genes, Department of Biochemistry, College of Life Sciences, Sun Yat-sen University, Higher Education Mega Center, Guangzhou, 510006, PR China
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38
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Pick L, Heffer A. Hoxgene evolution: multiple mechanisms contributing to evolutionary novelties. Ann N Y Acad Sci 2012; 1256:15-32. [DOI: 10.1111/j.1749-6632.2011.06385.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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39
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Park WJ, Kothapalli KSD, Reardon HT, Lawrence P, Qian SB, Brenna JT. A novel FADS1 isoform potentiates FADS2-mediated production of eicosanoid precursor fatty acids. J Lipid Res 2012; 53:1502-12. [PMID: 22619218 DOI: 10.1194/jlr.m025312] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The fatty acid desaturase (FADS) genes code for the rate-limiting enzymes required for the biosynthesis of long-chain polyunsaturated fatty acids (LCPUFA). Here we report discovery and function of a novel FADS1 splice variant. FADS1 alternative transcript 1 (FADS1AT1) enhances desaturation of FADS2, leading to increased production of eicosanoid precursors, the first case of an isoform modulating the enzymatic activity encoded by another gene. Multiple protein isoforms were detected in primate liver, thymus, and brain. In human neuronal cells, their expression patterns are modulated by differentiation and result in alteration of cellular fatty acids. FADS1, but not FADS1AT1, localizes to endoplasmic reticulum and mitochondria. Ribosomal footprinting demonstrates that all three FADS genes are translated at similar levels. The noncatalytic regulation of FADS2 desaturation by FADS1AT1 is a novel, plausible mechanism by which several phylogenetically conserved FADS isoforms may regulate LCPUFA biosynthesis in a manner specific to tissue, organelle, and developmental stage.
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Affiliation(s)
- Woo Jung Park
- Division of Nutritional Sciences, Cornell University, Ithaca, NY
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40
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Derti A, Garrett-Engele P, Macisaac KD, Stevens RC, Sriram S, Chen R, Rohl CA, Johnson JM, Babak T. A quantitative atlas of polyadenylation in five mammals. Genome Res 2012; 22:1173-83. [PMID: 22454233 PMCID: PMC3371698 DOI: 10.1101/gr.132563.111] [Citation(s) in RCA: 474] [Impact Index Per Article: 39.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
We developed PolyA-seq, a strand-specific and quantitative method for high-throughput sequencing of 3′ ends of polyadenylated transcripts, and used it to globally map polyadenylation (polyA) sites in 24 matched tissues in human, rhesus, dog, mouse, and rat. We show that PolyA-seq is as accurate as existing RNA sequencing (RNA-seq) approaches for digital gene expression (DGE), enabling simultaneous mapping of polyA sites and quantitative measurement of their usage. In human, we confirmed 158,533 known sites and discovered 280,857 novel sites (FDR < 2.5%). On average 10% of novel human sites were also detected in matched tissues in other species. Most novel sites represent uncharacterized alternative polyA events and extensions of known transcripts in human and mouse, but primarily delineate novel transcripts in the other three species. A total of 69.1% of known human genes that we detected have multiple polyA sites in their 3′UTRs, with 49.3% having three or more. We also detected polyadenylation of noncoding and antisense transcripts, including constitutive and tissue-specific primary microRNAs. The canonical polyA signal was strongly enriched and positionally conserved in all species. In general, usage of polyA sites is more similar within the same tissues across different species than within a species. These quantitative maps of polyA usage in evolutionarily and functionally related samples constitute a resource for understanding the regulatory mechanisms underlying alternative polyadenylation.
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Affiliation(s)
- Adnan Derti
- Department of Informatics IT, Merck and Co., Inc., Boston, Massachusetts 02115, USA
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41
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Three Drosophila Hox complex microRNAs do not have major effects on expression of evolutionarily conserved Hox gene targets during embryogenesis. PLoS One 2012; 7:e31365. [PMID: 22393361 PMCID: PMC3290615 DOI: 10.1371/journal.pone.0031365] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Accepted: 01/09/2012] [Indexed: 12/21/2022] Open
Abstract
The discovery of microRNAs has resulted in a major expansion of the number of molecules known to be involved in gene regulation. Elucidating the functions of animal microRNAs has posed a significant challenge as their target interactions with messenger RNAs do not adhere to simple rules. Of the thousands of known animal microRNAs, relatively few microRNA:messenger RNA regulatory interactions have been biologically validated in an normal organismal context. Here we present evidence that three microRNAs from the Hox complex in Drosophila (miR-10-5p, miR-10-3p, miR-iab-4-5p) do not have significant effects during embryogenesis on the expression of Hox genes that contain high confidence microRNAs target sites in the 3′ untranslated regions of their messenger RNAs. This is significant, in that it suggests that many predicted microRNA-target interactions may not be biologically relevant, or that the outcomes of these interactions may be so subtle that mutants may only show phenotypes in specific contexts, such as in environmental stress conditions, or in combinations with other microRNA mutations.
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42
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Lian C, Sun B, Niu S, Yang R, Liu B, Lu C, Meng J, Qiu Z, Zhang L, Zhao Z. A comparative profile of the microRNA transcriptome in immature and mature porcine testes using Solexa deep sequencing. FEBS J 2012; 279:964-75. [PMID: 22240065 DOI: 10.1111/j.1742-4658.2012.08480.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
MicroRNAs (miRNAs) are small noncoding regulatory RNAs that play key roles in many diverse biological processes such as spermatogenesis. However, no study has been performed on the miRNA transcriptome of developing porcine testes. Here, we employed Solexa deep sequencing technology to extend the repertoire of porcine testis miRNAs and extensively compare the expression patterns of sexually immature and mature porcine testes. Solexa sequencing of two small RNA libraries derived from immature (30 days) and mature (180 days) pig testis samples yielded over 25 million high-quality reads. Overall, the two developmental stages had significantly different small RNA compositions. A custom data analysis pipeline identified 398 known and/or homologous conserved porcine miRNAs, 15 novel pig-specific miRNAs and 56 novel candidate miRNAs. We further observed multiple mature miRNA variants and identified a new bidirectional transcribed miRNA locus, ssc-mir-181a. A total of 122 miRNAs were differentially expressed in the immature and mature testes, and 10 were validated using quantitative RT-PCR. Furthermore, GO and KEGG pathway analyses of the predicted miRNA targets further illustrate the likely roles for these differentially expressed miRNAs in spermatogenesis. This study is the first comparative profile of the miRNA transcriptome in immature and mature porcine testes using a deep sequencing approach, and it provides a useful resource for future studies on the role of miRNAs in spermatogenesis and male infertility treatment.
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Affiliation(s)
- Chuanjiang Lian
- College of Animal Science and Veterinary Medicine, Jilin Provincial Key Laboratory of Animal Embryo Engineering, Jilin University, China
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43
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Shortening of 3'UTRs correlates with poor prognosis in breast and lung cancer. PLoS One 2012; 7:e31129. [PMID: 22347440 PMCID: PMC3275581 DOI: 10.1371/journal.pone.0031129] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Accepted: 01/03/2012] [Indexed: 02/06/2023] Open
Abstract
A major part of the post-transcriptional regulation of gene expression is affected by trans-acting elements, such as microRNAs, binding the 3' untraslated region (UTR) of their target mRNAs. Proliferating cells partly escape this type of negative regulation by expressing shorter 3' UTRs, depleted of microRNA binding sites, compared to non-proliferating cells. Using large-scale gene expression datasets, we show that a similar phenomenon takes place in breast and lung cancer: tumors expressing shorter 3' UTRs tend to be more aggressive and to result in shorter patient survival. Moreover, we show that a gene expression signature based only on the expression ratio of alternative 3' UTRs is a strong predictor of survival in both tumors. Genes undergoing 3'UTR shortening in aggressive tumors of the two tissues significantly overlap, and several of them are known to be involved in tumor progression. However the pattern of 3' UTR shortening in aggressive tumors in vivo is clearly distinct from analogous patterns involved in proliferation and transformation.
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44
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A complex 'mRNA degradation code' controls gene expression during animal development. Trends Genet 2012; 28:78-88. [PMID: 22257633 DOI: 10.1016/j.tig.2011.10.005] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Revised: 10/26/2011] [Accepted: 10/27/2011] [Indexed: 11/22/2022]
Abstract
Current understanding of the molecular mechanisms underlying mRNA degradation indicates that specific mRNA degradation rates are primarily encoded within the mRNA message itself in the form of cis-regulatory elements bearing particular primary sequences and/or secondary-structures. Such control elements are operated by RNA-binding proteins (RBPs) and/or miRNA-containing complexes. Based on the large number of RBPs and miRNAs encoded in metazoan genomes, their complex developmental expression and that specific RBP and miRNA interactions with mRNAs can lead to distinct degradation rates, I propose that developmental gene expression is shaped by a complex 'mRNA degradation code' with high information capacity. Localised cellular events involving the modification of RBP and/or miRNA target sequences in mRNAs by alternative polyadenylation added to the activation of specific RBP and miRNA activities via cell signalling are predicted to further expand the capacity of the mRNA degradation code by coupling it to dynamic events experienced by cells at specific spatiotemporal coordinates within the developing embryo.
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45
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Mansfield JH, McGlinn E. Evolution, Expression, and Developmental Function of Hox-Embedded miRNAs. Curr Top Dev Biol 2012; 99:31-57. [DOI: 10.1016/b978-0-12-387038-4.00002-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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46
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Abstract
Axon regeneration is a fundamental problem facing neuroscientists and clinicians. Failure of axon regeneration is caused by both extrinsic and intrinsic mechanisms. New techniques to examine gene expression such as Next Generation Sequencing of the Transcriptome (RNA-Seq) drastically increase our knowledge of both gene expression complexity (RNA isoforms) and gene expression regulation. By utilizing RNA-Seq, gene expression can now be defined at the level of isoforms, an essential step for understanding the mechanisms governing cell identity, growth and ultimately cellular responses to injury and disease.
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Affiliation(s)
- Jessica K Lerch
- The Miami Project to Cure Paralysis, The University of Miami, Miami, FL, USA
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47
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Neural-specific elongation of 3' UTRs during Drosophila development. Proc Natl Acad Sci U S A 2011; 108:15864-9. [PMID: 21896737 DOI: 10.1073/pnas.1112672108] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The 3' termini of eukaryotic mRNAs influence transcript stability, translation efficiency, and subcellular localization. Here we report that a subset of developmental regulatory genes, enriched in critical RNA-processing factors, exhibits synchronous lengthening of their 3' UTRs during embryogenesis. The resulting UTRs are up to 20-fold longer than those found on typical Drosophila mRNAs. The large mRNAs emerge shortly after the onset of zygotic transcription, with several of these genes acquiring additional, phased UTR extensions later in embryogenesis. We show that these extended 3' UTR sequences are selectively expressed in neural tissues and contain putative recognition motifs for the translational repressor, Pumilio, which also exhibits the 3' lengthening phenomenon documented in this study. These findings suggest a previously unknown mode of posttranscriptional regulation that may contribute to the complexity of neurogenesis or neural function.
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48
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Patraquim P, Warnefors M, Alonso CR. Evolution of Hox post-transcriptional regulation by alternative polyadenylation and microRNA modulation within 12 Drosophila genomes. Mol Biol Evol 2011; 28:2453-60. [PMID: 21436120 DOI: 10.1093/molbev/msr073] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Hox genes encode a family of transcriptional regulators that operate differential developmental programs along the anteroposterior axis of bilateral animals. Regulatory changes affecting Hox gene expression are believed to have been crucial for the evolution of animal body plans. In Drosophila melanogaster, Hox expression is post-transcriptionally regulated by microRNAs (miRNAs) acting on target sites located in the 3' untranslated regions (3'UTRs) of Hox mRNAs. Notably, recent work has shown that during D. melanogaster development Hox genes produce mRNAs with variable 3'UTRs (short and long forms) in different sets of tissues as a result of alternative polyadenylation; importantly, Hox short and long 3'UTRs contain very different target sites for miRNAs. Here, we use a computational approach to explore the evolution of Hox 3'UTRs treated with especial regard to miRNA regulation. Our work is focused on the 12 Drosophila species for which genomic sequences are available and shows, first, that alternative polyadenylation of Hox transcripts is a feature shared by all drosophilids tested in the study. Second, that the regulatory impact of miRNAs is evolving very fast within the Drosophila group. Third, that in contrast to the low degree of primary sequence conservation, Hox 3'UTR regions within the group show very similar RNA topology indicating that RNA structure is under strong selective pressure. Finally, we also demonstrate that Hox alternative polyadenylation can remodel the control regions seen by miRNAs by at least two mechanisms: via adding new cis-regulatory sequences-in the form of miRNA target sites-to short 3'UTR forms as well as by modifying the regulatory impact of miRNA target sites in short 3'UTR forms through changes in RNA secondary structure caused by the use of distal polyadenylation signals.
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Affiliation(s)
- Pedro Patraquim
- School of Life Sciences, University of Sussex, Brighton, United Kingdom
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49
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Abstract
Non-coding RNAs (ncRNAs) are emerging as key regulators of embryogenesis. They control embryonic gene expression by several means, ranging from microRNA-induced degradation of mRNAs to long ncRNA-mediated modification of chromatin. Many aspects of embryogenesis seem to be controlled by ncRNAs, including the maternal-zygotic transition, the maintenance of pluripotency, the patterning of the body axes, the specification and differentiation of cell types and the morphogenesis of organs. Drawing from several animal model systems, we describe two emerging themes for ncRNA function: promoting developmental transitions and maintaining developmental states. These examples also highlight the roles of ncRNAs in ensuring a robust commitment to one of two possible cell fates.
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Affiliation(s)
- Andrea Pauli
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
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50
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Enderle D, Beisel C, Stadler MB, Gerstung M, Athri P, Paro R. Polycomb preferentially targets stalled promoters of coding and noncoding transcripts. Genome Res 2010; 21:216-26. [PMID: 21177970 DOI: 10.1101/gr.114348.110] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The Polycomb group (PcG) and Trithorax group (TrxG) of proteins are required for stable and heritable maintenance of repressed and active gene expression states. Their antagonistic function on gene control, repression for PcG and activity for TrxG, is mediated by binding to chromatin and subsequent epigenetic modification of target loci. Despite our broad knowledge about composition and enzymatic activities of the protein complexes involved, our understanding still lacks important mechanistic detail and a comprehensive view on target genes. In this study we use an extensive data set of ChIP-seq, RNA-seq, and genome-wide detection of transcription start sites (TSSs) to identify and analyze thousands of binding sites for the PcG proteins and Trithorax from a Drosophila S2 cell line. In addition of finding a preference for stalled promoter regions of annotated genes, we uncover many intergenic PcG binding sites coinciding with nonannotated TSSs. Interestingly, this set includes previously unknown promoters for primary transcripts of microRNA genes, thereby expanding the scope of Polycomb control to noncoding RNAs essential for development, apoptosis, and growth.
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Affiliation(s)
- Daniel Enderle
- Department of Biosystems Science and Engineering, ETH Zurich, CH-4058 Basel, Switzerland
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