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Powers EN, Chan C, Doron-Mandel E, Llacsahuanga Allcca L, Kim Kim J, Jovanovic M, Brar GA. Bidirectional promoter activity from expression cassettes can drive off-target repression of neighboring gene translation. eLife 2022; 11:e81086. [PMID: 36503721 PMCID: PMC9754628 DOI: 10.7554/elife.81086] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 11/28/2022] [Indexed: 12/14/2022] Open
Abstract
Targeted selection-based genome-editing approaches have enabled many fundamental discoveries and are used routinely with high precision. We found, however, that replacement of DBP1 with a common selection cassette in budding yeast led to reduced expression and function for the adjacent gene, MRP51, despite all MRP51 coding and regulatory sequences remaining intact. Cassette-induced repression of MRP51 drove all mutant phenotypes detected in cells deleted for DBP1. This behavior resembled the 'neighboring gene effect' (NGE), a phenomenon of unknown mechanism whereby cassette insertion at one locus reduces the expression of a neighboring gene. Here, we leveraged strong off-target mutant phenotypes resulting from cassette replacement of DBP1 to provide mechanistic insight into the NGE. We found that the inherent bidirectionality of promoters, including those in expression cassettes, drives a divergent transcript that represses MRP51 through combined transcriptional interference and translational repression mediated by production of a long undecoded transcript isoform (LUTI). Divergent transcript production driving this off-target effect is general to yeast expression cassettes and occurs ubiquitously with insertion. Despite this, off-target effects are often naturally prevented by local sequence features, such as those that terminate divergent transcripts between the site of cassette insertion and the neighboring gene. Thus, cassette-induced off-target effects can be eliminated by the insertion of transcription terminator sequences into the cassette, flanking the promoter. Because the driving features of this off-target effect are broadly conserved, our study suggests it should be considered in the design and interpretation of experiments using integrated expression cassettes in other eukaryotic systems, including human cells.
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Affiliation(s)
- Emily Nicole Powers
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
| | - Charlene Chan
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
| | - Ella Doron-Mandel
- Department of Biological Sciences, Columbia UniversityNew YorkUnited States
| | | | - Jenny Kim Kim
- Department of Biological Sciences, Columbia UniversityNew YorkUnited States
| | - Marko Jovanovic
- Department of Biological Sciences, Columbia UniversityNew YorkUnited States
| | - Gloria Ann Brar
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
- California Institute for Quantitative Biosciences (QB3), University of California, BerkleyBerkleyUnited States
- Center for Computational Biology, University of California, BerkeleyBerkeleyUnited States
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2
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Sato S, Dacher M, Kurumizaka H. Nucleosome Structures Built from Highly Divergent Histones: Parasites and Giant DNA Viruses. EPIGENOMES 2022; 6:epigenomes6030022. [PMID: 35997368 PMCID: PMC9396995 DOI: 10.3390/epigenomes6030022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 07/29/2022] [Accepted: 07/29/2022] [Indexed: 02/04/2023] Open
Abstract
In eukaryotes, genomic DNA is bound with histone proteins and packaged into chromatin. The nucleosome, a fundamental unit of chromatin, regulates the accessibility of DNA to enzymes involved in gene regulation. During the past few years, structural analyses of chromatin architectures have been limited to evolutionarily related organisms. The amino acid sequences of histone proteins are highly conserved from humans to yeasts, but are divergent in the deeply branching protozoan groups, including human parasites that are directly related to human health. Certain large DNA viruses, as well as archaeal organisms, contain distant homologs of eukaryotic histone proteins. The divergent sequences give rise to unique and distinct nucleosome architectures, although the fundamental principles of histone folding and DNA contact are highly conserved. In this article, we review the structures and biophysical properties of nucleosomes containing histones from the human parasites Giardia lamblia and Leishmania major, and histone-like proteins from the Marseilleviridae amoeba virus family. The presented data confirm the sharing of the overall DNA compaction system among evolutionally distant species and clarify the deviations from the species-specific nature of the nucleosome.
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Multimodal regulation of encystation in Giardia duodenalis revealed by deep proteomics. Int J Parasitol 2021; 51:809-824. [PMID: 34331939 DOI: 10.1016/j.ijpara.2021.01.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 12/24/2020] [Accepted: 01/07/2021] [Indexed: 12/21/2022]
Abstract
Cyst formation in the parasitic protist Giardia duodenalis is critical to its transmission. Existing proteomic data quantifies only 17% of coding genes transcribed during encystation and does not cover the complete process from trophozoite to mature cyst. Using high-resolution mass spectrometry, we have quantified proteomic changes across encystation and compared this with published transcriptomic data. We reproducibly identified 3863 (64.5% of Giardia proteins) and quantified 3382 proteins (56.5% of Giardia proteins) over standard trophozoite growth (TY), during low-bile encystation priming (LB), 16 h into encystation (EC), and at cyst maturation (C). This work provides the first known expanded observation of encystation at the proteomic level and triples the coverage of previous encystation proteomes. One-third (1169 proteins) of the quantified proteome is differentially expressed in the mature cyst relative to the trophozoite, including proteasomal machinery, metabolic pathways, and secretory proteins. Changes in lipid metabolism indicated a shift in lipid species dependency during encystation. Consistent with this, we identified the first, putative lipid transporters in this species, representing the steroidogenic acute regulatory protein-related lipid transfer (StARkin), oxysterol binding protein related protein (ORP/Osh) and glycosphingolipid transfer protein (GLTP) families, and follow their differential expression over cyst formation. Lastly, we undertook correlation analyses of the transcriptome and proteome of trophozoites and cysts, and found evidence of post-transcriptional regulation of key protein classes (RNA binding proteins) and stage-specific genes (encystation markers) implicating translation-repression in encystation. We provide the most extensive proteomic analysis of encystation in Giardia to date and the first known exploration across its complete duration. This work identifies encystation as highly coordinated, involving major changes in proteostasis, metabolism and membrane dynamics, and indicates a potential role for post-transcriptional regulation, mediated through RNA-binding proteins. Together our work provides a valuable resource for Giardia research and the development of transmission-blocking anti-giardials.
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4
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Li Y, Baptista RP, Sateriale A, Striepen B, Kissinger JC. Analysis of Long Non-Coding RNA in Cryptosporidium parvum Reveals Significant Stage-Specific Antisense Transcription. Front Cell Infect Microbiol 2021; 10:608298. [PMID: 33520737 PMCID: PMC7840661 DOI: 10.3389/fcimb.2020.608298] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2020] [Accepted: 11/26/2020] [Indexed: 12/13/2022] Open
Abstract
Cryptosporidium is a protist parasite that has been identified as the second leading cause of moderate to severe diarrhea in children younger than two and a significant cause of mortality worldwide. Cryptosporidium has a complex, obligate, intracellular but extra cytoplasmic lifecycle in a single host. How genes are regulated in this parasite remains largely unknown. Long non-coding RNAs (lncRNAs) play critical regulatory roles, including gene expression across a broad range of organisms. Cryptosporidium lncRNAs have been reported to enter the host cell nucleus and affect the host response. However, no systematic study of lncRNAs in Cryptosporidium has been conducted to identify additional lncRNAs. In this study, we analyzed a C. parvum in vitro strand-specific RNA-seq developmental time series covering both asexual and sexual stages to identify lncRNAs associated with parasite development. In total, we identified 396 novel lncRNAs, mostly antisense, with 86% being differentially expressed. Surprisingly, nearly 10% of annotated mRNAs have an antisense transcript. lncRNAs occur most often at the 3' end of their corresponding sense mRNA. Putative lncRNA regulatory regions were identified and many appear to encode bidirectional promoters. A positive correlation between lncRNA and upstream mRNA expression was observed. Evolutionary conservation and expression of lncRNA candidates was observed between C. parvum, C. hominis and C. baileyi. Ten C. parvum protein-encoding genes with antisense transcripts have P. falciparum orthologs that also have antisense transcripts. Three C. parvum lncRNAs with exceptional properties (e.g., intron splicing) were experimentally validated using RT-PCR and RT-qPCR. This initial characterization of the C. parvum non-coding transcriptome facilitates further investigations into the roles of lncRNAs in parasite development and host-pathogen interactions.
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Affiliation(s)
- Yiran Li
- Institute of Bioinformatics, University of Georgia, Athens, GA, United States
| | - Rodrigo P. Baptista
- Institute of Bioinformatics, University of Georgia, Athens, GA, United States
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, United States
| | - Adam Sateriale
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Boris Striepen
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Jessica C. Kissinger
- Institute of Bioinformatics, University of Georgia, Athens, GA, United States
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, United States
- Department of Genetics, University of Georgia, Athens, GA, United States
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5
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Eukaryote-conserved histone post-translational modification landscape in Giardia duodenalis revealed by mass spectrometry. Int J Parasitol 2020; 51:225-239. [PMID: 33275945 DOI: 10.1016/j.ijpara.2020.09.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 09/01/2020] [Accepted: 09/22/2020] [Indexed: 12/15/2022]
Abstract
Diarrheal disease caused by Giardia duodenalis is highly prevalent, causing over 200 million cases globally each year. The processes that drive parasite virulence, host immune evasion and transmission involve coordinated gene expression and have been linked to epigenetic regulation. Epigenetic regulatory systems are eukaryote-conserved, including in deep branching excavates such as Giardia, with several studies already implicating histone post-translational modifications in regulation of its pathogenesis and life cycle. However, further insights into Giardia chromatin dynamics have been hindered by a lack of site-specific knowledge of histone modifications. Using mass spectrometry, we have provided the first known molecular map of histone methylation, acetylation and phosphorylation modifications in Giardia core histones. We have identified over 50 previously unreported histone modifications including sites with established roles in epigenetic regulation, and co-occurring modifications indicative of post-translational modification crosstalk. These demonstrate conserved histone modifications in Giardia which are equivalent to many other eukaryotes, and suggest that similar epigenetic mechanisms are in place in this parasite. Further, we used sequence, domain and structural homology to annotate putative histone enzyme networks in Giardia, highlighting representative chromatin modifiers which appear sufficient for identified sites, particularly those from H3 and H4 variants. This study is to our knowledge the first and most comprehensive, complete and accurate view of Giardia histone post-translational modifications to date, and a substantial step towards understanding their associations in parasite development and virulence.
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Najdrová V, Stairs CW, Vinopalová M, Voleman L, Doležal P. The evolution of the Puf superfamily of proteins across the tree of eukaryotes. BMC Biol 2020; 18:77. [PMID: 32605621 PMCID: PMC7325665 DOI: 10.1186/s12915-020-00814-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 06/18/2020] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Eukaryotic gene expression is controlled by a number of RNA-binding proteins (RBP), such as the proteins from the Puf (Pumilio and FBF) superfamily (PufSF). These proteins bind to RNA via multiple Puf repeat domains, each of which specifically recognizes a single RNA base. Recently, three diversified PufSF proteins have been described in model organisms, each of which is responsible for the maturation of ribosomal RNA or the translational regulation of mRNAs; however, less is known about the role of these proteins across eukaryotic diversity. RESULTS Here, we investigated the distribution and function of PufSF RBPs in the tree of eukaryotes. We determined that the following PufSF proteins are universally conserved across eukaryotes and can be broadly classified into three groups: (i) Nop9 orthologues, which participate in the nucleolar processing of immature 18S rRNA; (ii) 'classical' Pufs, which control the translation of mRNA; and (iii) PUM3 orthologues, which are involved in the maturation of 7S rRNA. In nearly all eukaryotes, the rRNA maturation proteins, Nop9 and PUM3, are retained as a single copy, while mRNA effectors ('classical' Pufs) underwent multiple lineage-specific expansions. We propose that the variation in number of 'classical' Pufs relates to the size of the transcriptome and thus the potential mRNA targets. We further distinguished full set of PufSF proteins in divergent metamonad Giardia intestinalis and initiated their cellular and biochemical characterization. CONCLUSIONS Our data suggest that the last eukaryotic common ancestor (LECA) already contained all three types of PufSF proteins and that 'classical' Pufs then underwent lineage-specific expansions.
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Affiliation(s)
- Vladimíra Najdrová
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Průmyslová 595, 252 50, Vestec, Czech Republic
| | - Courtney W Stairs
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, SE-75123, Uppsala, Sweden
| | - Martina Vinopalová
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Průmyslová 595, 252 50, Vestec, Czech Republic
| | - Luboš Voleman
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Průmyslová 595, 252 50, Vestec, Czech Republic
| | - Pavel Doležal
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Průmyslová 595, 252 50, Vestec, Czech Republic.
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7
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Long Non-Coding RNAs in the Regulation of Gene Expression: Physiology and Disease. Noncoding RNA 2019; 5:ncrna5010017. [PMID: 30781588 PMCID: PMC6468922 DOI: 10.3390/ncrna5010017] [Citation(s) in RCA: 373] [Impact Index Per Article: 74.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 02/11/2019] [Accepted: 02/12/2019] [Indexed: 02/07/2023] Open
Abstract
The identification of RNAs that are not translated into proteins was an important breakthrough, defining the diversity of molecules involved in eukaryotic regulation of gene expression. These non-coding RNAs can be divided into two main classes according to their length: short non-coding RNAs, such as microRNAs (miRNAs), and long non-coding RNAs (lncRNAs). The lncRNAs in association with other molecules can coordinate several physiological processes and their dysfunction may impact in several pathologies, including cancer and infectious diseases. They can control the flux of genetic information, such as chromosome structure modulation, transcription, splicing, messenger RNA (mRNA) stability, mRNA availability, and post-translational modifications. Long non-coding RNAs present interaction domains for DNA, mRNAs, miRNAs, and proteins, depending on both sequence and secondary structure. The advent of new generation sequencing has provided evidences of putative lncRNAs existence; however, the analysis of transcriptomes for their functional characterization remains a challenge. Here, we review some important aspects of lncRNA biology, focusing on their role as regulatory elements in gene expression modulation during physiological and disease processes, with implications in host and pathogens physiology, and their role in immune response modulation.
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8
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Emery SJ, Baker L, Ansell BRE, Mirzaei M, Haynes PA, McConville MJ, Svärd SG, Jex AR. Differential protein expression and post-translational modifications in metronidazole-resistant Giardia duodenalis. Gigascience 2018; 7:4931738. [PMID: 29688452 PMCID: PMC5913674 DOI: 10.1093/gigascience/giy024] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 03/06/2018] [Indexed: 01/20/2023] Open
Abstract
Background Metronidazole (Mtz) is the frontline drug treatment for multiple anaerobic pathogens, including the gastrointestinal protist, Giardia duodenalis. However, treatment failure is common and linked to in vivo drug resistance. In Giardia, in vitro drug-resistant lines allow controlled experimental interrogation of resistance mechanisms in isogenic cultures. However, resistance-associated changes are inconsistent between lines, phenotypic data are incomplete, and resistance is rarely genetically fixed, highlighted by reversion to sensitivity after drug selection ceases or via passage through the life cycle. Comprehensive quantitative approaches are required to resolve isolate variability, fully define Mtz resistance phenotypes, and explore the role of post-translational modifications therein. Findings We performed quantitative proteomics to describe differentially expressed proteins in 3 seminal Mtz-resistant lines compared to their isogenic, Mtz-susceptible, parental line. We also probed changes in post-translational modifications including protein acetylation, methylation, ubiquitination, and phosphorylation via immunoblotting. We quantified more than 1,000 proteins in each genotype, recording substantial genotypic variation in differentially expressed proteins between isotypes. Our data confirm substantial changes in the antioxidant network, glycolysis, and electron transport and indicate links between protein acetylation and Mtz resistance, including cross-resistance to deacetylase inhibitor trichostatin A in Mtz-resistant lines. Finally, we performed the first controlled, longitudinal study of Mtz resistance stability, monitoring lines after cessation of drug selection, revealing isolate-dependent phenotypic plasticity. Conclusions Our data demonstrate understanding that Mtz resistance must be broadened to post-transcriptional and post-translational responses and that Mtz resistance is polygenic, driven by isolate-dependent variation, and is correlated with changes in protein acetylation networks.
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Affiliation(s)
- Samantha J Emery
- Population Health and Immunity Division, Walter and Eliza Hall Institute of Medical Research, Melbourne, VIC, Australia
| | - Louise Baker
- Population Health and Immunity Division, Walter and Eliza Hall Institute of Medical Research, Melbourne, VIC, Australia.,Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Melbourne, VIC, Australia
| | - Brendan R E Ansell
- Population Health and Immunity Division, Walter and Eliza Hall Institute of Medical Research, Melbourne, VIC, Australia.,Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Melbourne, VIC, Australia
| | - Mehdi Mirzaei
- Chemistry and Biomolecular Sciences, Faculty of Science, Macquarie University, North Ryde, NSW, Australia.,Australian Proteome Analysis Facility, Macquarie University, North Ryde, NSW, Australia
| | - Paul A Haynes
- Chemistry and Biomolecular Sciences, Faculty of Science, Macquarie University, North Ryde, NSW, Australia
| | - Malcom J McConville
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC, Australia
| | - Staffan G Svärd
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Aaron R Jex
- Population Health and Immunity Division, Walter and Eliza Hall Institute of Medical Research, Melbourne, VIC, Australia.,Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Melbourne, VIC, Australia
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Ortega-Pierres M, Jex AR, Ansell BR, Svärd SG. Recent advances in the genomic and molecular biology of Giardia. Acta Trop 2018; 184:67-72. [PMID: 28888474 DOI: 10.1016/j.actatropica.2017.09.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 09/05/2017] [Indexed: 01/01/2023]
Abstract
Giardia duodenalis is the most common gastrointestinal protozoan parasite of humans and a significant contributor to the global burden of both diarrheal disease and post-infectious chronic disorders. Robust tools for analyzing gene function in this parasite have been developed and a range of genetic tools are now available. These together with public databases have provided insights on the function of different genes in Giardia. In this review we provide a current perspective on different molecular aspects of Giardia related to genomics, regulation of encystation, trophozoite transcriptional responses to physiological and xenobiotic (drug-induced) stress, and mechanisms of drug resistance. We also examine recent insights that have contributed to gain knowledge in the study of VSPs, antigenic variation, epigenetics, DNA repair and in the direct manipulation of gene function in Giardia, with a particular focus on the inducible Cre/loxP system.
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10
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Marinov GK, Kundaje A. ChIP-ping the branches of the tree: functional genomics and the evolution of eukaryotic gene regulation. Brief Funct Genomics 2018; 17:116-137. [PMID: 29529131 PMCID: PMC5889016 DOI: 10.1093/bfgp/ely004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Advances in the methods for detecting protein-DNA interactions have played a key role in determining the directions of research into the mechanisms of transcriptional regulation. The most recent major technological transformation happened a decade ago, with the move from using tiling arrays [chromatin immunoprecipitation (ChIP)-on-Chip] to high-throughput sequencing (ChIP-seq) as a readout for ChIP assays. In addition to the numerous other ways in which it is superior to arrays, by eliminating the need to design and manufacture them, sequencing also opened the door to carrying out comparative analyses of genome-wide transcription factor occupancy across species and studying chromatin biology in previously less accessible model and nonmodel organisms, thus allowing us to understand the evolution and diversity of regulatory mechanisms in unprecedented detail. Here, we review the biological insights obtained from such studies in recent years and discuss anticipated future developments in the field.
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Affiliation(s)
- Georgi K Marinov
- Corresponding author: Georgi K. Marinov, Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA. E-mail:
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Emery SJ, Lacey E, Haynes PA. Quantitative proteomics in Giardia duodenalis —Achievements and challenges. Mol Biochem Parasitol 2016; 208:96-112. [DOI: 10.1016/j.molbiopara.2016.07.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 07/13/2016] [Accepted: 07/16/2016] [Indexed: 12/31/2022]
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12
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Inhibición parcial de dos genes que codifican para proteínas spliceosomales en Giardia intestinalis. BIOMEDICA 2016; 36:128-36. [DOI: 10.7705/biomedica.v36i0.3068] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Revised: 02/29/2016] [Indexed: 11/21/2022]
Abstract
<p><strong>Introducción.</strong> <em>Giardia intestinalis</em> es un organismo tempranamente divergente en el que recientemente se demostró la presencia de intrones. La maquinaria responsable de la remoción de intrones en eucariotes superiores es el spliceosoma, conformado por 5 ribonucleoproteínas. Cada una tiene un ARN pequeño nuclear, un set de 7 proteínas Sm (B, D1, D2, D3, E, F y G) y varias proteínas específicas. En <em>G. intestinalis</em>, se han identificado los genes de algunas proteínas del spliceosoma por bioinformática. Aunque se asume que el spliceosoma es el responsable del splicing en el parásito, su caracterización bioquímica no ha sido realizada.</p><p><strong>Objetivo.</strong> Inhibir dos genes que codifican para proteínas del spliceosoma de <em>G. intestinalis</em> con el fin de determinar si esta inhibición afecta el crecimiento o la enquistación del parásito.</p><p><strong>Materiales y métodos.</strong> Se clonaron en un vector específico para <em>G. intestinalis</em> secuencias antisentido de los genes que codifican para las proteínas spliceosomales SmB y SmD3 del parásito. Posteriormente se transfectó <em>G. intestinalis</em> con los vectores recombinantes y se seleccionaron aquellos parásitos que lo incorporaron. Se confirmó la disminución del mensajero por PCR en tiempo real y se evaluó el crecimiento y la enquistación en parásitos silvestres y transfectados.</p><p><strong>Resultados.</strong> Se observó una disminución del 40% y 70% en el mARN de SmB y SmD3, respectivamente. El crecimiento y la enquistación no se vieron afectados en estos parásitos.</p><p><strong>Conclusión. </strong>La disminución de SmB y SmD3 no afectan el parásito, indicando que el spliceosoma sigue siendo funcional o que el splicing no es una función vital del parásito.</p>
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Ansell BRE, McConville MJ, Baker L, Korhonen PK, Young ND, Hall RS, Rojas CAA, Svärd SG, Gasser RB, Jex AR. Time-Dependent Transcriptional Changes in Axenic Giardia duodenalis Trophozoites. PLoS Negl Trop Dis 2015; 9:e0004261. [PMID: 26636323 PMCID: PMC4670223 DOI: 10.1371/journal.pntd.0004261] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 11/03/2015] [Indexed: 12/27/2022] Open
Abstract
Giardia duodenalis is the most common gastrointestinal protozoan parasite of humans and a significant contributor to the global burden of both diarrheal disease and post-infectious chronic disorders. Although G. duodenalis can be cultured axenically, significant gaps exist in our understanding of the molecular biology and metabolism of this pathogen. The present study employed RNA sequencing to characterize the mRNA transcriptome of G. duodenalis trophozoites in axenic culture, at log (48 h of growth), stationary (60 h), and declining (96 h) growth phases. Using ~400-times coverage of the transcriptome, we identified 754 differentially transcribed genes (DTGs), mainly representing two large DTG groups: 438 that were down-regulated in the declining phase relative to log and stationary phases, and 281 that were up-regulated. Differential transcription of prominent antioxidant and glycolytic enzymes implicated oxygen tension as a key factor influencing the transcriptional program of axenic trophozoites. Systematic bioinformatic characterization of numerous DTGs encoding hypothetical proteins of unknown function was achieved using structural homology searching. This powerful approach greatly informed the differential transcription analysis and revealed putative novel antioxidant-coding genes, and the presence of a near-complete two-component-like signaling system that may link cytosolic redox or metabolite sensing to the observed transcriptional changes. Motif searching applied to promoter regions of the two large DTG groups identified different putative transcription factor-binding motifs that may underpin global transcriptional regulation. This study provides new insights into the drivers and potential mediators of transcriptional variation in axenic G. duodenalis and provides context for static transcriptional studies.
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Affiliation(s)
- Brendan R. E. Ansell
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Malcolm J. McConville
- Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
| | - Louise Baker
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Pasi K. Korhonen
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Neil D. Young
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Ross S. Hall
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Cristian A. A. Rojas
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Staffan G. Svärd
- Department of Cell & Molecular Biology, Biomedical Center, Uppsala University, Uppsala, Sweden
| | - Robin B. Gasser
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Aaron R. Jex
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Victoria, Australia
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14
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Transcriptional profiling of Giardia intestinalis in response to oxidative stress. Int J Parasitol 2015; 45:925-38. [DOI: 10.1016/j.ijpara.2015.07.005] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Revised: 06/17/2015] [Accepted: 07/24/2015] [Indexed: 12/20/2022]
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15
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Xu F, Jerlström-Hultqvist J, Einarsson E, Ástvaldsson Á, Svärd SG, Andersson JO. The genome of Spironucleus salmonicida highlights a fish pathogen adapted to fluctuating environments. PLoS Genet 2014; 10:e1004053. [PMID: 24516394 PMCID: PMC3916229 DOI: 10.1371/journal.pgen.1004053] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Accepted: 11/08/2013] [Indexed: 11/18/2022] Open
Abstract
Spironucleus salmonicida causes systemic infections in salmonid fish. It belongs to the group diplomonads, binucleated heterotrophic flagellates adapted to micro-aerobic environments. Recently we identified energy-producing hydrogenosomes in S. salmonicida. Here we present a genome analysis of the fish parasite with a focus on the comparison to the more studied diplomonad Giardia intestinalis. We annotated 8067 protein coding genes in the ∼12.9 Mbp S. salmonicida genome. Unlike G. intestinalis, promoter-like motifs were found upstream of genes which are correlated with gene expression, suggesting a more elaborate transcriptional regulation. S. salmonicida can utilise more carbohydrates as energy sources, has an extended amino acid and sulfur metabolism, and more enzymes involved in scavenging of reactive oxygen species compared to G. intestinalis. Both genomes have large families of cysteine-rich membrane proteins. A cluster analysis indicated large divergence of these families in the two diplomonads. Nevertheless, one of S. salmonicida cysteine-rich proteins was localised to the plasma membrane similar to G. intestinalis variant-surface proteins. We identified S. salmonicida homologs to cyst wall proteins and showed that one of these is functional when expressed in Giardia. This suggests that the fish parasite is transmitted as a cyst between hosts. The extended metabolic repertoire and more extensive gene regulation compared to G. intestinalis suggest that the fish parasite is more adapted to cope with environmental fluctuations. Our genome analyses indicate that S. salmonicida is a well-adapted pathogen that can colonize different sites in the host. Studies of model organisms are very powerful. However, to appreciate the enormous diversity of genetic and cell biological processes we need to extend the number of available model organisms. For example, there are very few model organisms for diverse microbial eukaryotes, a group of organisms which indeed represents the vast majority of the eukaryotic diversity. To this end, we have developed a system to do genetic modification on the Atlantic salmon pathogen Spironucleus salmonicida. Using this system we could show that the organism is capable of producing hydrogen within specialised compartments. Here we present the genome sequence of S. salmonicida together with a thorough annotation. We compare the results with the closest available model organism, the human intestinal parasite Giardia intestinalis. The fish parasite has a more elaborate system for regulation of gene expression, as well as a larger metabolic capacity. This indicates that S. salmonicida is a well-adapted pathogen that can deal with fluctuating environments, an important trait to be able to establish systemic infections in the host. The development of S. salmonicida into a model system will benefit the studies of fish infections, as well as cell biological processes.
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Affiliation(s)
- Feifei Xu
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, BMC, Uppsala, Sweden
| | - Jon Jerlström-Hultqvist
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, BMC, Uppsala, Sweden
| | - Elin Einarsson
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, BMC, Uppsala, Sweden
| | - Ásgeir Ástvaldsson
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, BMC, Uppsala, Sweden
| | - Staffan G. Svärd
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, BMC, Uppsala, Sweden
| | - Jan O. Andersson
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, BMC, Uppsala, Sweden
- * E-mail:
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Tolba MEM, Kobayashi S, Imada M, Suzuki Y, Sugano S. Giardia lamblia transcriptome analysis using TSS-Seq and RNA-Seq. PLoS One 2013; 8:e76184. [PMID: 24116096 PMCID: PMC3792122 DOI: 10.1371/journal.pone.0076184] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Accepted: 08/21/2013] [Indexed: 11/19/2022] Open
Abstract
Giardia lamblia is a protozoan parasite that is found worldwide and has both medical and veterinary importance. We applied the transcription start sequence (TSS-seq) and RNA sequence (RNA-seq) techniques to study the transcriptome of the assemblage A WB strain trophozoite. We identified 8000 transcription regions (TR) with significant transcription. Of these regions, 1881 TRs were more than 500 nucleotides upstream of an annotated ORF. Combining both techniques helped us to identify 24 ORFs that should be re-annotated and 60 new ORFs. From the 8000 TRs, we were able to identify an AT-rich consensus that includes the transcription initiation site. It is possible that transcription that was previously thought to be bidirectional is actually unidirectional.
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Affiliation(s)
- Mohammed E. M. Tolba
- Department of Medical Genomics, Graduate School of Frontier Sciences, The University of Tokyo, Tokyo, Japan
- Department of Parasitology, Faculty of Medicine, Assiut University, Assiut, Egypt
| | - Seiki Kobayashi
- Department of Infectious Diseases, School of Medicine, Keio University, Tokyo, Japan
| | - Mihoko Imada
- Department of Infectious Diseases, School of Medicine, Keio University, Tokyo, Japan
| | - Yutaka Suzuki
- Department of Medical Genomics, Graduate School of Frontier Sciences, The University of Tokyo, Tokyo, Japan
| | - Sumio Sugano
- Department of Medical Genomics, Graduate School of Frontier Sciences, The University of Tokyo, Tokyo, Japan
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Franzén O, Jerlström-Hultqvist J, Einarsson E, Ankarklev J, Ferella M, Andersson B, Svärd SG. Transcriptome profiling of Giardia intestinalis using strand-specific RNA-seq. PLoS Comput Biol 2013; 9:e1003000. [PMID: 23555231 PMCID: PMC3610916 DOI: 10.1371/journal.pcbi.1003000] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Accepted: 02/02/2013] [Indexed: 01/08/2023] Open
Abstract
Giardia intestinalis is a common cause of diarrheal disease and it consists of eight genetically distinct genotypes or assemblages (A-H). Only assemblages A and B infect humans and are suggested to represent two different Giardia species. Correlations exist between assemblage type and host-specificity and to some extent symptoms. Phenotypical differences have been documented between assemblages and genome sequences are available for A, B and E. We have characterized and compared the polyadenylated transcriptomes of assemblages A, B and E. Four genetically different isolates were studied (WB (AI), AS175 (AII), P15 (E) and GS (B)) using paired-end, strand-specific RNA-seq. Most of the genome was transcribed in trophozoites grown in vitro, but at vastly different levels. RNA-seq confirmed many of the present annotations and refined the current genome annotation. Gene expression divergence was found to recapitulate the known phylogeny, and uncovered lineage-specific differences in expression. Polyadenylation sites were mapped for over 70% of the genes and revealed many examples of conserved and unexpectedly long 3′ UTRs. 28 open reading frames were found in a non-transcribed gene cluster on chromosome 5 of the WB isolate. Analysis of allele-specific expression revealed a correlation between allele-dosage and allele expression in the GS isolate. Previously reported cis-splicing events were confirmed and global mapping of cis-splicing identified only one novel intron. These observations can possibly explain differences in host-preference and symptoms, and it will be the basis for further studies of Giardia pathogenesis and biology. Giardia is a single cell intestinal parasite and a common cause of diarrhea in humans and animals. Giardia is an unusual eukaryote by possessing two nuclei, a highly reduced genome and simple transcriptional apparatus. We have characterized the transcriptome of Giardia at single nucleotide resolution, which allowed the calculation of digital gene expression values for the complete set of genes. We performed a comparison of gene expression divergence across three genotypes. Most of the genes were transcribed, and the data were used to refine and correct gene models. Several gene expression differences were identified between the genotypes. A non-transcribed cluster of genes was detected on chromosome 5, likely representing a silenced region. The data also allowed mapping of transcript termini, which provided the first global view of 3′ untranslated regions in this parasite. This study also gives the first genome-wide evidence of transcription of allelic variants in Giardia. In this study, we provide novel insights into the transcriptome of an important human pathogen and model eukaryote. The findings reported here likely relate to the lifestyle of this parasite and its adaptation to parasitism. The data provide starting points for functional investigation of Giardia's biology and diplomonads generally.
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Affiliation(s)
- Oscar Franzén
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | | | - Elin Einarsson
- Department of Cell and Molecular Biology, BMC, Uppsala University, Uppsala, Sweden
| | - Johan Ankarklev
- Department of Cell and Molecular Biology, BMC, Uppsala University, Uppsala, Sweden
| | - Marcela Ferella
- Department of Cell and Molecular Biology, BMC, Uppsala University, Uppsala, Sweden
| | - Björn Andersson
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Staffan G. Svärd
- Department of Cell and Molecular Biology, BMC, Uppsala University, Uppsala, Sweden
- * E-mail:
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Zhang H, Ehrenkaufer GM, Hall N, Singh U. Small RNA pyrosequencing in the protozoan parasite Entamoeba histolytica reveals strain-specific small RNAs that target virulence genes. BMC Genomics 2013; 14:53. [PMID: 23347563 PMCID: PMC3610107 DOI: 10.1186/1471-2164-14-53] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2012] [Accepted: 01/02/2013] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Small RNA mediated gene silencing is a well-conserved regulatory pathway. In the parasite Entamoeba histolytica an endogenous RNAi pathway exists, however, the depth and diversity of the small RNA population remains unknown. RESULTS To characterize the small RNA population that associates with E. histolytica Argonaute-2 (EhAGO2-2), we immunoprecipitated small RNAs that associate with it and performed one full pyrosequencing run. Data analysis revealed new features of the 27nt small RNAs including the 5'-G predominance, distinct small RNA distribution patterns on protein coding genes, small RNAs mapping to both introns and exon-exon junctions, and small RNA targeted genes that are clustered particularly in sections of genome duplication. Characterization of genomic loci to which both sense and antisense small RNAs mapped showed that both sets of small RNAs have 5'-polyphosphate termini; strand-specific RT-PCR detected transcripts in both directions at these loci suggesting that both transcripts may serve as template for small RNA generation. In order to determine whether small RNA abundance patterns account for strain-specific gene expression profiles of E. histolytica virulent and non-virulent strains, we sequenced small RNAs from a non-virulent strain and found that small RNAs mapped to genes in a manner consistent with their regulation of strain-specific virulence genes. CONCLUSIONS We provided a full spectrum analysis for E. histolytica AGO2-2 associated 27nt small RNAs. Additionally, comparative analysis of small RNA populations from virulent and non-virulent amebic strains indicates that small RNA populations may regulate virulence genes.
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Affiliation(s)
- Hanbang Zhang
- Division of Infectious Diseases, Department of Internal Medicine, Stanford University School of Medicine, Stanford, California 94305-5107, USA
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Collins LJ. Characterizing ncRNAs in Human Pathogenic Protists Using High-Throughput Sequencing Technology. Front Genet 2011; 2:96. [PMID: 22303390 PMCID: PMC3268645 DOI: 10.3389/fgene.2011.00096] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2011] [Accepted: 12/07/2011] [Indexed: 11/16/2022] Open
Abstract
ncRNAs are key genes in many human diseases including cancer and viral infection, as well as providing critical functions in pathogenic organisms such as fungi, bacteria, viruses, and protists. Until now the identification and characterization of ncRNAs associated with disease has been slow or inaccurate requiring many years of testing to understand complicated RNA and protein gene relationships. High-throughput sequencing now offers the opportunity to characterize miRNAs, siRNAs, small nucleolar RNAs (snoRNAs), and long ncRNAs on a genomic scale, making it faster and easier to clarify how these ncRNAs contribute to the disease state. However, this technology is still relatively new, and ncRNA discovery is not an application of high priority for streamlined bioinformatics. Here we summarize background concepts and practical approaches for ncRNA analysis using high-throughput sequencing, and how it relates to understanding human disease. As a case study, we focus on the parasitic protists Giardia lamblia and Trichomonas vaginalis, where large evolutionary distance has meant difficulties in comparing ncRNAs with those from model eukaryotes. A combination of biological, computational, and sequencing approaches has enabled easier classification of ncRNA classes such as snoRNAs, but has also aided the identification of novel classes. It is hoped that a higher level of understanding of ncRNA expression and interaction may aid in the development of less harsh treatment for protist-based diseases.
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Affiliation(s)
- Lesley Joan Collins
- Institute of Fundamental Sciences, Massey University Palmerston North, New Zealand
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20
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Williams CW, Elmendorf HG. Identification and analysis of the RNA degrading complexes and machinery of Giardia lamblia using an in silico approach. BMC Genomics 2011; 12:586. [PMID: 22126454 PMCID: PMC3282835 DOI: 10.1186/1471-2164-12-586] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Accepted: 11/29/2011] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND RNA degradation is critical to the survival of all cells. With increasing evidence for pervasive transcription in cells, RNA degradation has gained recognition as a means of regulating gene expression. Yet, RNA degradation machinery has been studied extensively in only a few eukaryotic organisms, including Saccharomyces cerevisiae and humans. Giardia lamblia is a parasitic protist with unusual genomic traits: it is binucleated and tetraploid, has a very compact genome, displays a theme of genomic minimalism with cellular machinery commonly comprised of a reduced number of protein components, and has a remarkably large population of long, stable, noncoding, antisense RNAs. RESULTS Here we use in silico approaches to investigate the major RNA degradation machinery in Giardia lamblia and compare it to a broad array of other parasitic protists. We have found key constituents of the deadenylation and decapping machinery and of the 5'-3' RNA degradation pathway. We have similarly found that all of the major 3'-5' RNA degradation pathways are present in Giardia, including both exosome-dependent and exosome-independent machinery. However, we observe significant loss of RNA degradation machinery genes that will result in important differences in the protein composition, and potentially functionality, of the various RNA degradation pathways. This is most apparent in the exosome, the central mediator of 3'-5' degradation, which apparently contains an altered core configuration in both Giardia and Plasmodium, with only four, instead of the canonical six, distinct subunits. Additionally the exosome in Giardia is missing both the Rrp6, Nab3, and Nrd1 proteins, known to be key regulators of noncoding transcript stability in other cells. CONCLUSIONS These findings suggest that although the full complement of the major RNA degradation mechanisms were present - and likely functional - early in eukaryotic evolution, the composition and function of the complexes is more variable than previously appreciated. We suggest that the missing components of the exosome complex provide an explanation for the stable abundance of sterile RNA species in Giardia.
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Affiliation(s)
| | - Heidi G Elmendorf
- Department of Biology, Georgetown University, Washington, DC 20057, USA
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21
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Chen XS, Penny D, Collins LJ. Characterization of RNase MRP RNA and novel snoRNAs from Giardia intestinalis and Trichomonas vaginalis. BMC Genomics 2011; 12:550. [PMID: 22053856 PMCID: PMC3228867 DOI: 10.1186/1471-2164-12-550] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Accepted: 11/06/2011] [Indexed: 12/02/2022] Open
Abstract
Background Eukaryotic cells possess a complex network of RNA machineries which function in RNA-processing and cellular regulation which includes transcription, translation, silencing, editing and epigenetic control. Studies of model organisms have shown that many ncRNAs of the RNA-infrastructure are highly conserved, but little is known from non-model protists. In this study we have conducted a genome-scale survey of medium-length ncRNAs from the protozoan parasites Giardia intestinalis and Trichomonas vaginalis. Results We have identified the previously 'missing' Giardia RNase MRP RNA, which is a key ribozyme involved in pre-rRNA processing. We have also uncovered 18 new H/ACA box snoRNAs, expanding our knowledge of the H/ACA family of snoRNAs. Conclusions Results indicate that Giardia intestinalis and Trichomonas vaginalis, like their distant multicellular relatives, contain a rich infrastructure of RNA-based processing. From here we can investigate the evolution of RNA processing networks in eukaryotes.
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Affiliation(s)
- Xiaowei S Chen
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
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22
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Identification of Scaffold/Matrix Attachment (S/MAR) like DNA element from the gastrointestinal protozoan parasite Giardia lamblia. BMC Genomics 2010; 11:386. [PMID: 20565887 PMCID: PMC3017767 DOI: 10.1186/1471-2164-11-386] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2009] [Accepted: 06/18/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Chromatin in the nucleus of all eukaryotes is organized into a system of loops and domains. These loops remain fastened at their bases to the fundamental framework of the nucleus, the matrix or the scaffold. The DNA sequences which anchor the bases of the chromatin loops to the matrix are known as Scaffold/Matrix Attachment Regions or S/MARs. Though S/MARs have been studied in yeast and higher eukaryotes and they have been found to be associated with gene organization and regulation of gene expression, they have not been reported in protists like Giardia. Several tools have been discovered and formulated to predict S/MARs from a genome of a higher eukaryote which take into account a number of features. However, the lack of a definitive consensus sequence in S/MARs and the randomness of the protozoan genome in general, make it a challenge to predict and identify such sequences from protists. RESULTS Here, we have analysed the Giardia genome for the probable S/MARs predicted by the available computational tools; and then shown these sequences to be physically associated with the nuclear matrix. Our study also reflects that while no single computational tool is competent to predict such complex elements from protist genomes, a combination of tools followed by experimental verification is the only way to confirm the presence of these elements from these organisms. CONCLUSION This is the first report of S/MAR elements from the protozoan parasite Giardia lamblia. This initial work is expected to lay a framework for future studies relating to genome organization as well as gene regulatory elements in this parasite.
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Birkeland SR, Preheim SP, Davids BJ, Cipriano MJ, Palm D, Reiner DS, Svärd SG, Gillin FD, McArthur AG. Transcriptome analyses of the Giardia lamblia life cycle. Mol Biochem Parasitol 2010; 174:62-5. [PMID: 20570699 DOI: 10.1016/j.molbiopara.2010.05.010] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2010] [Revised: 05/11/2010] [Accepted: 05/12/2010] [Indexed: 10/19/2022]
Abstract
We quantified mRNA abundance from 10 stages in the Giardia lamblia life cycle in vitro using Serial Analysis of Gene Expression (SAGE). 163 abundant transcripts were expressed constitutively. 71 transcripts were upregulated specifically during excystation and 42 during encystation. Nonetheless, the transcriptomes of cysts and trophozoites showed major differences. SAGE detected co-expressed clusters of 284 transcripts differentially expressed in cysts and excyzoites and 287 transcripts in vegetative trophozoites and encysting cells. All clusters included known genes and pathways as well as proteins unique to Giardia or diplomonads. SAGE analysis of the Giardia life cycle identified a number of kinases, phosphatases, and DNA replication proteins involved in excystation and encystation, which could be important for examining the roles of cell signaling in giardial differentiation. Overall, these data pave the way for directed gene discovery and a better understanding of the biology of G. lamblia.
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Affiliation(s)
- Shanda R Birkeland
- Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, Woods Hole, MA 02543, USA
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Brower CS, Veiga L, Jones RH, Varshavsky A. Mouse Dfa is a repressor of TATA-box promoters and interacts with the Abt1 activator of basal transcription. J Biol Chem 2010; 285:17218-34. [PMID: 20356838 DOI: 10.1074/jbc.m110.118638] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Our study of the mouse Ate1 arginyltransferase, a component of the N-end rule pathway, has shown that Ate1 pre-mRNA is produced from a bidirectional promoter that also expresses, in the opposite direction, a previously uncharacterized gene (Hu, R. G., Brower, C. S., Wang, H., Davydov, I. V., Sheng, J., Zhou, J., Kwon, Y. T., and Varshavsky, A. (2006) J. Biol. Chem. 281, 32559-32573). In this work, we began analyzing this gene, termed Dfa (divergent from Ate1). Mouse Dfa was found to be transcribed from both the bidirectional P(Ate1/Dfa) promoter and other nearby promoters. The resulting transcripts are alternatively spliced, yielding a complex set of Dfa mRNAs that are present largely, although not exclusively, in the testis. A specific Dfa mRNA encodes, via its 3'-terminal exon, a 217-residue protein termed Dfa(A). Other Dfa mRNAs also contain this exon. Dfa(A) is sequelogous (similar in sequence) to a region of the human/mouse HTEX4 protein, whose physiological function is unknown. We produced an affinity-purified antibody to recombinant mouse Dfa(A) that detected a 35-kDa protein in the mouse testis and in several cell lines. Experiments in which RNA interference was used to down-regulate Dfa indicated that the 35-kDa protein was indeed Dfa(A). Furthermore, Dfa(A) was present in the interchromatin granule clusters and was also found to bind to the Ggnbp1 gametogenetin-binding protein-1 and to the Abt1 activator of basal transcription that interacts with the TATA-binding protein. Given these results, RNA interference was used to probe the influence of Dfa levels in luciferase reporter assays. We found that Dfa(A) acts as a repressor of TATA-box transcriptional promoters.
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Affiliation(s)
- Christopher S Brower
- Division of Biology, California Institute of Technology, Pasadena, California 91125, USA
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25
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Cong P, Luo Y, Bao W, Hu S. Genomic organization and promoter analysis of the Trichomonas vaginalis core histone gene families. Parasitol Int 2010; 59:29-34. [DOI: 10.1016/j.parint.2009.08.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2009] [Revised: 08/23/2009] [Accepted: 08/25/2009] [Indexed: 11/25/2022]
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26
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Xie ZH. [Natural antisense transcript and its mechanism of gene regulation]. YI CHUAN = HEREDITAS 2010; 32:122-128. [PMID: 20176555 DOI: 10.3724/sp.j.1005.2010.00122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Natural antisense transcripts (NATs) are coding or non-coding RNAs with sequence complementarity to other transcripts (sense transcripts). These RNAs could potentially regulate the expression of their sense partner(s) at either the transcriptional or post-transcriptional level through a variety of biological mechanisms, such as transcription interference, RNA masking, dsRNA-dependent mechanisms, and chromatin remodelling (modification). We speculated that both of sense and antisense transcripts may be sliced to form small RNAs, which is also an important mechanism for NATs to regulate gene expression, such as rasiRNAs in "ping-pong". Experimental and computational analyses have demonstrated the wide-spread occurrence of NATs in a wide range of species. Here, we reviewed the current understanding of NATs function and its mechanistic basis. We hypothesized that the regulation of antisense transcription and small RNAs were derived from NATs.
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Affiliation(s)
- Zhao-Hui Xie
- Department of Biology, Dezhou University, Dezhou 253023, China.
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Peyretaillade E, Gonçalves O, Terrat S, Dugat-Bony E, Wincker P, Cornman RS, Evans JD, Delbac F, Peyret P. Identification of transcriptional signals in Encephalitozoon cuniculi widespread among Microsporidia phylum: support for accurate structural genome annotation. BMC Genomics 2009; 10:607. [PMID: 20003517 PMCID: PMC2803860 DOI: 10.1186/1471-2164-10-607] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2009] [Accepted: 12/15/2009] [Indexed: 11/22/2022] Open
Abstract
Background Microsporidia are obligate intracellular eukaryotic parasites with genomes ranging in size from 2.3 Mbp to more than 20 Mbp. The extremely small (2.9 Mbp) and highly compact (~1 gene/kb) genome of the human parasite Encephalitozoon cuniculi has been fully sequenced. The aim of this study was to characterize noncoding motifs that could be involved in regulation of gene expression in E. cuniculi and to show whether these motifs are conserved among the phylum Microsporidia. Results To identify such signals, 5' and 3'RACE-PCR experiments were performed on different E. cuniculi mRNAs. This analysis confirmed that transcription overrun occurs in E. cuniculi and may result from stochastic recognition of the AAUAAA polyadenylation signal. Such experiments also showed highly reduced 5'UTR's (<7 nts). Most of the E. cuniculi genes presented a CCC-like motif immediately upstream from the coding start. To characterize other signals involved in differential transcriptional regulation, we then focused our attention on the gene family coding for ribosomal proteins. An AAATTT-like signal was identified upstream from the CCC-like motif. In rare cases the cytosine triplet was shown to be substituted by a GGG-like motif. Comparative genomic studies confirmed that these different signals are also located upstream from genes encoding ribosomal proteins in other microsporidian species including Antonospora locustae, Enterocytozoon bieneusi, Anncaliia algerae (syn. Brachiola algerae) and Nosema ceranae. Based on these results a systematic analysis of the ~2000 E. cuniculi coding DNA sequences was then performed and brings to highlight that 364 translation initiation codons (18.29% of total CDSs) had been badly predicted. Conclusion We identified various signals involved in the maturation of E. cuniculi mRNAs. Presence of such signals, in phylogenetically distant microsporidian species, suggests that a common regulatory mechanism exists among the microsporidia. Furthermore, 5'UTRs being strongly reduced, these signals can be used to ensure the accurate prediction of translation initiation codons for microsporidian genes and to improve microsporidian genome annotation.
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Affiliation(s)
- Eric Peyretaillade
- Clermont Université, Université d'Auvergne, Laboratoire: Microorganismes Génome et Environnement, BP 10448, F-63000 CLERMONT-FERRAND.
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28
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Belostotsky D. Exosome complex and pervasive transcription in eukaryotic genomes. Curr Opin Cell Biol 2009; 21:352-8. [DOI: 10.1016/j.ceb.2009.04.011] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2009] [Revised: 04/19/2009] [Accepted: 04/20/2009] [Indexed: 12/27/2022]
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Abstract
The long polycistronic transcription units of trypanosomes do not appear to be demarcated by the usual DNA motifs that punctuate transcription in familiar eukaryotes. In this issue of Genes & Development, Siegel and colleagues (pp. 1063-1076) describe a system for the demarcation of trypanosome transcription units based on the deposition and turnover of histone variants rather than on the binding of transcription factors. Replication-independent incorporation of histone variants and destabilization of nucleosomes is an emerging theme at promoters of more familiar eukaryotes, and it now appears that this system is an evolutionarily conserved mode of transcriptional punctuation.
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Affiliation(s)
- Paul B Talbert
- Howard Hughes Medical Institute, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA.
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Benachenhou F, Jern P, Oja M, Sperber G, Blikstad V, Somervuo P, Kaski S, Blomberg J. Evolutionary conservation of orthoretroviral long terminal repeats (LTRs) and ab initio detection of single LTRs in genomic data. PLoS One 2009; 4:e5179. [PMID: 19365549 PMCID: PMC2664473 DOI: 10.1371/journal.pone.0005179] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2008] [Accepted: 03/10/2009] [Indexed: 01/06/2023] Open
Abstract
Background Retroviral LTRs, paired or single, influence the transcription of both retroviral and non-retroviral genomic sequences. Vertebrate genomes contain many thousand endogenous retroviruses (ERVs) and their LTRs. Single LTRs are difficult to detect from genomic sequences without recourse to repetitiveness or presence in a proviral structure. Understanding of LTR structure increases understanding of LTR function, and of functional genomics. Here we develop models of orthoretroviral LTRs useful for detection in genomes and for structural analysis. Principal Findings Although mutated, ERV LTRs are more numerous and diverse than exogenous retroviral (XRV) LTRs. Hidden Markov models (HMMs), and alignments based on them, were created for HML- (human MMTV-like), general-beta-, gamma- and lentiretroviruslike LTRs, plus a general-vertebrate LTR model. Training sets were XRV LTRs and RepBase LTR consensuses. The HML HMM was most sensitive and detected 87% of the HML LTRs in human chromosome 19 at 96% specificity. By combining all HMMs with a low cutoff, for screening, 71% of all LTRs found by RepeatMasker in chromosome 19 were found. HMM consensus sequences had a conserved modular LTR structure. Target site duplications (TG-CA), TATA (occasionally absent), an AATAAA box and a T-rich region were prominent features. Most of the conservation was located in, or adjacent to, R and U5, with evidence for stem loops. Several of the long HML LTRs contained long ORFs inserted after the second A rich module. HMM consensus alignment allowed comparison of functional features like transcriptional start sites (sense and antisense) between XRVs and ERVs. Conclusion The modular conserved and redundant orthoretroviral LTR structure with three A-rich regions is reminiscent of structurally relaxed Giardia promoters. The five HMMs provided a novel broad range, repeat-independent, ab initio LTR detection, with prospects for greater generalisation, and insight into LTR structure, which may aid development of LTR-targeted pharmaceuticals.
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Affiliation(s)
- Farid Benachenhou
- Section of Virology, Department of Medical Sciences, Uppsala University, Uppsala, Sweden
| | - Patric Jern
- Section of Virology, Department of Medical Sciences, Uppsala University, Uppsala, Sweden
| | - Merja Oja
- Helsinki Institute for Information Technology, Department of Computer Science, University of Helsinki and Laboratory of Computer and Information Science, Helsinki University of Technology, Helsinki, Finland
| | - Göran Sperber
- Unit of Physiology, Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Vidar Blikstad
- Section of Virology, Department of Medical Sciences, Uppsala University, Uppsala, Sweden
| | - Panu Somervuo
- Helsinki Institute for Information Technology, Department of Computer Science, University of Helsinki and Laboratory of Computer and Information Science, Helsinki University of Technology, Helsinki, Finland
| | - Samuel Kaski
- Helsinki Institute for Information Technology, Department of Computer Science, University of Helsinki and Laboratory of Computer and Information Science, Helsinki University of Technology, Helsinki, Finland
| | - Jonas Blomberg
- Section of Virology, Department of Medical Sciences, Uppsala University, Uppsala, Sweden
- * E-mail:
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Widespread bidirectional promoters are the major source of cryptic transcripts in yeast. Nature 2009; 457:1038-42. [PMID: 19169244 DOI: 10.1038/nature07747] [Citation(s) in RCA: 464] [Impact Index Per Article: 30.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2008] [Accepted: 12/24/2008] [Indexed: 11/09/2022]
Abstract
Pervasive and hidden transcription is widespread in eukaryotes, but its global level, the mechanisms from which it originates and its functional significance are unclear. Cryptic unstable transcripts (CUTs) were recently described as a principal class of RNA polymerase II transcripts in Saccharomyces cerevisiae. These transcripts are targeted for degradation immediately after synthesis by the action of the Nrd1-exosome-TRAMP complexes. Although CUT degradation mechanisms have been analysed in detail, the genome-wide distribution at the nucleotide resolution and the prevalence of CUTs are unknown. Here we report the first high-resolution genomic map of CUTs in yeast, revealing a class of potentially functional CUTs and the intrinsic bidirectional nature of eukaryotic promoters. An RNA fraction highly enriched in CUTs was analysed by a 3' Long-SAGE (serial analysis of gene expression) approach adapted to deep sequencing. The resulting detailed genomic map of CUTs revealed that they derive from extremely widespread and very well defined transcription units and do not result from unspecific transcriptional noise. Moreover, the transcription of CUTs predominantly arises within nucleosome-free regions, most of which correspond to promoter regions of bona fide genes. Some of the CUTs start upstream from messenger RNAs and overlap their 5' end. Our study of glycolysis genes, as well as recent results from the literature, indicate that such concurrent transcription is potentially associated with regulatory mechanisms. Our data reveal numerous new CUTs with such a potential regulatory role. However, most of the identified CUTs corresponded to transcripts divergent from the promoter regions of genes, indicating that they represent by-products of divergent transcription occurring at many and possibly most promoters. Eukaryotic promoter regions are thus intrinsically bidirectional, a fundamental property that escaped previous analyses because in most cases divergent transcription generates short-lived unstable transcripts present at very low steady-state levels.
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Bidirectional promoters generate pervasive transcription in yeast. Nature 2009; 457:1033-7. [PMID: 19169243 DOI: 10.1038/nature07728] [Citation(s) in RCA: 735] [Impact Index Per Article: 49.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2008] [Accepted: 12/19/2008] [Indexed: 01/18/2023]
Abstract
Genome-wide pervasive transcription has been reported in many eukaryotic organisms, revealing a highly interleaved transcriptome organization that involves hundreds of previously unknown non-coding RNAs. These recently identified transcripts either exist stably in cells (stable unannotated transcripts, SUTs) or are rapidly degraded by the RNA surveillance pathway (cryptic unstable transcripts, CUTs). One characteristic of pervasive transcription is the extensive overlap of SUTs and CUTs with previously annotated features, which prompts questions regarding how these transcripts are generated, and whether they exert function. Single-gene studies have shown that transcription of SUTs and CUTs can be functional, through mechanisms involving the generated RNAs or their generation itself. So far, a complete transcriptome architecture including SUTs and CUTs has not been described in any organism. Knowledge about the position and genome-wide arrangement of these transcripts will be instrumental in understanding their function. Here we provide a comprehensive analysis of these transcripts in the context of multiple conditions, a mutant of the exosome machinery and different strain backgrounds of Saccharomyces cerevisiae. We show that both SUTs and CUTs display distinct patterns of distribution at specific locations. Most of the newly identified transcripts initiate from nucleosome-free regions (NFRs) associated with the promoters of other transcripts (mostly protein-coding genes), or from NFRs at the 3' ends of protein-coding genes. Likewise, about half of all coding transcripts initiate from NFRs associated with promoters of other transcripts. These data change our view of how a genome is transcribed, indicating that bidirectionality is an inherent feature of promoters. Such an arrangement of divergent and overlapping transcripts may provide a mechanism for local spreading of regulatory signals-that is, coupling the transcriptional regulation of neighbouring genes by means of transcriptional interference or histone modification.
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Abstract
Non-protein-coding sequences increasingly dominate the genomes of multicellular organisms as their complexity increases, in contrast to protein-coding genes, which remain relatively static. Most of the mammalian genome and indeed that of all eukaryotes is expressed in a cell- and tissue-specific manner, and there is mounting evidence that much of this transcription is involved in the regulation of differentiation and development. Different classes of small and large noncoding RNAs (ncRNAs) have been shown to regulate almost every level of gene expression, including the activation and repression of homeotic genes and the targeting of chromatin-remodeling complexes. ncRNAs are involved in developmental processes in both simple and complex eukaryotes, and we illustrate this in the latter by focusing on the animal germline, brain, and eye. While most have yet to be systematically studied, the emerging evidence suggests that there is a vast hidden layer of regulatory ncRNAs that constitutes the majority of the genomic programming of multicellular organisms and plays a major role in controlling the epigenetic trajectories that underlie their ontogeny.
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Militello KT, Refour P, Comeaux CA, Duraisingh MT. Antisense RNA and RNAi in protozoan parasites: working hard or hardly working? Mol Biochem Parasitol 2007; 157:117-26. [PMID: 18053590 DOI: 10.1016/j.molbiopara.2007.10.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2007] [Revised: 10/11/2007] [Accepted: 10/12/2007] [Indexed: 10/22/2022]
Abstract
The complex life cycles of many protozoan parasites require the ability to respond to environmental and developmental cues through regulated gene expression. Traditionally, parasitologists have investigated these mechanisms by identifying and characterizing proteins that are necessary for the regulated expression of the genetic material. Although often successful, it is clear that protein-mediated gene regulation is only part of a complex story in which RNA itself is endowed with regulatory functions. Herein, we review both the known and potential regulatory roles of two types of RNA pathways within protozoan parasites: the RNA interference pathway and natural antisense transcripts. A better understanding of the native role of these pathways will not only enhance our understanding of the biology of these organisms but also aid in the development of more robust tools for reverse genetic analysis in this post-genomic era.
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Affiliation(s)
- Kevin T Militello
- Department of Biology, State University of New York at Geneseo, Geneseo, NY, USA
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