1
|
Grypioti E, Richard H, Kryovrysanaki N, Jaubert M, Falciatore A, Verret F, Kalantidis K. Dicer-dependent heterochromatic small RNAs in the model diatom species Phaeodactylum tricornutum. THE NEW PHYTOLOGIST 2024; 241:811-826. [PMID: 38044751 DOI: 10.1111/nph.19429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 10/17/2023] [Indexed: 12/05/2023]
Abstract
Diatoms are eukaryotic microalgae responsible for nearly half of the marine productivity. RNA interference (RNAi) is a mechanism of regulation of gene expression mediated by small RNAs (sRNAs) processed by the endoribonuclease Dicer (DCR). To date, the mechanism and physiological role of RNAi in diatoms are unknown. We mined diatom genomes and transcriptomes for key RNAi effectors and retraced their phylogenetic history. We generated DCR knockout lines in the model diatom species Phaeodactylum tricornutum and analyzed their mRNA and sRNA populations, repression-associated histone marks, and acclimatory response to nitrogen starvation. Diatoms presented a diversification of key RNAi effectors whose distribution across species suggests the presence of distinct RNAi pathways. P. tricornutum DCR was found to process 26-31-nt-long double-stranded sRNAs originating mostly from transposons covered by repression-associated epigenetic marks. In parallel, P. tricornutum DCR was necessary for the maintenance of the repression-associated histone marks H3K9me2/3 and H3K27me3. Finally, PtDCR-KO lines presented a compromised recovery post nitrogen starvation suggesting a role for P. tricornutum DCR in the acclimation to nutrient stress. Our study characterized the molecular function of the single DCR homolog of P. tricornutum suggesting an association between RNAi and heterochromatin maintenance in this model diatom species.
Collapse
Affiliation(s)
- Emilia Grypioti
- Department of Biology, University of Crete, PO Box 2208, 70013, Heraklion, Crete, Greece
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, 70013, Heraklion, Crete, Greece
- Institute of Marine Biology and Aquaculture, Hellenic Center for Marine Research, 71500, Gournes, Crete, Greece
- Institut de Biologie Paris-Seine, Laboratory of Computational and Quantitative Biology, UMR 7238 Sorbonne Université, 75005, Paris, France
| | - Hugues Richard
- Institut de Biologie Paris-Seine, Laboratory of Computational and Quantitative Biology, UMR 7238 Sorbonne Université, 75005, Paris, France
- Bioinformatics Unit, Genome Competence Center (MF1), Robert Koch Institute, 13353, Berlin, Germany
| | - Nikoleta Kryovrysanaki
- Department of Biology, University of Crete, PO Box 2208, 70013, Heraklion, Crete, Greece
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, 70013, Heraklion, Crete, Greece
| | - Marianne Jaubert
- Institut de Biologie Paris-Seine, Laboratory of Computational and Quantitative Biology, UMR 7238 Sorbonne Université, 75005, Paris, France
- Institut de Biologie Physico-Chimique, Laboratory of Chloroplast Biology and Light Sensing in Microalgae, UMR7141 Centre National de la Recherche Scientifique (CNRS), Sorbonne Université, 75005, Paris, France
| | - Angela Falciatore
- Institut de Biologie Paris-Seine, Laboratory of Computational and Quantitative Biology, UMR 7238 Sorbonne Université, 75005, Paris, France
- Institut de Biologie Physico-Chimique, Laboratory of Chloroplast Biology and Light Sensing in Microalgae, UMR7141 Centre National de la Recherche Scientifique (CNRS), Sorbonne Université, 75005, Paris, France
| | - Frédéric Verret
- Department of Biology, University of Crete, PO Box 2208, 70013, Heraklion, Crete, Greece
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, 70013, Heraklion, Crete, Greece
- Institute of Marine Biology and Aquaculture, Hellenic Center for Marine Research, 71500, Gournes, Crete, Greece
| | - Kriton Kalantidis
- Department of Biology, University of Crete, PO Box 2208, 70013, Heraklion, Crete, Greece
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, 70013, Heraklion, Crete, Greece
| |
Collapse
|
2
|
Gaona-López C, Vazquez-Jimenez LK, Gonzalez-Gonzalez A, Delgado-Maldonado T, Ortiz-Pérez E, Nogueda-Torres B, Moreno-Rodríguez A, Vázquez K, Saavedra E, Rivera G. Advances in Protozoan Epigenetic Targets and Their Inhibitors for the Development of New Potential Drugs. Pharmaceuticals (Basel) 2023; 16:ph16040543. [PMID: 37111300 PMCID: PMC10143871 DOI: 10.3390/ph16040543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 03/29/2023] [Accepted: 03/31/2023] [Indexed: 04/29/2023] Open
Abstract
Protozoan parasite diseases cause significant mortality and morbidity worldwide. Factors such as climate change, extreme poverty, migration, and a lack of life opportunities lead to the propagation of diseases classified as tropical or non-endemic. Although there are several drugs to combat parasitic diseases, strains resistant to routinely used drugs have been reported. In addition, many first-line drugs have adverse effects ranging from mild to severe, including potential carcinogenic effects. Therefore, new lead compounds are needed to combat these parasites. Although little has been studied regarding the epigenetic mechanisms in lower eukaryotes, it is believed that epigenetics plays an essential role in vital aspects of the organism, from controlling the life cycle to the expression of genes involved in pathogenicity. Therefore, using epigenetic targets to combat these parasites is foreseen as an area with great potential for development. This review summarizes the main known epigenetic mechanisms and their potential as therapeutics for a group of medically important protozoal parasites. Different epigenetic mechanisms are discussed, highlighting those that can be used for drug repositioning, such as histone post-translational modifications (HPTMs). Exclusive parasite targets are also emphasized, including the base J and DNA 6 mA. These two categories have the greatest potential for developing drugs to treat or eradicate these diseases.
Collapse
Affiliation(s)
- Carlos Gaona-López
- Laboratorio de Biotecnología Farmacéutica, Centro de Biotecnología Genómica, Instituto Politécnico Nacional, Reynosa 88710, Mexico
| | - Lenci K Vazquez-Jimenez
- Laboratorio de Biotecnología Farmacéutica, Centro de Biotecnología Genómica, Instituto Politécnico Nacional, Reynosa 88710, Mexico
| | - Alonzo Gonzalez-Gonzalez
- Laboratorio de Biotecnología Farmacéutica, Centro de Biotecnología Genómica, Instituto Politécnico Nacional, Reynosa 88710, Mexico
| | - Timoteo Delgado-Maldonado
- Laboratorio de Biotecnología Farmacéutica, Centro de Biotecnología Genómica, Instituto Politécnico Nacional, Reynosa 88710, Mexico
| | - Eyrá Ortiz-Pérez
- Laboratorio de Biotecnología Farmacéutica, Centro de Biotecnología Genómica, Instituto Politécnico Nacional, Reynosa 88710, Mexico
| | - Benjamín Nogueda-Torres
- Departamento de Parasitología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City 11340, Mexico
| | - Adriana Moreno-Rodríguez
- Laboratorio de Estudios Epidemiológicos, Clínicos, Diseños Experimentales e Investigación, Facultad de Ciencias Químicas, Universidad Autónoma "Benito Juárez" de Oaxaca, Avenida Universidad S/N, Ex Hacienda Cinco Señores, Oaxaca 68120, Mexico
| | - Karina Vázquez
- Facultad de Medicina Veterinaria y Zootecnia, Universidad Autónoma de Nuevo León, Francisco Villa 20, General Escobedo 66054, Mexico
| | - Emma Saavedra
- Departamento de Bioquímica, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City 14080, Mexico
| | - Gildardo Rivera
- Laboratorio de Biotecnología Farmacéutica, Centro de Biotecnología Genómica, Instituto Politécnico Nacional, Reynosa 88710, Mexico
| |
Collapse
|
3
|
Horjales S, Li Calzi M, Francia ME, Cayota A, Garcia-Silva MR. piRNA pathway evolution beyond gonad context: Perspectives from apicomplexa and trypanosomatids. Front Genet 2023; 14:1129194. [PMID: 36816026 PMCID: PMC9935688 DOI: 10.3389/fgene.2023.1129194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 01/23/2023] [Indexed: 02/05/2023] Open
Abstract
piRNAs function as genome defense mechanisms against transposable elements insertions within germ line cells. Recent studies have unraveled that piRNA pathways are not limited to germ cells as initially reckoned, but are instead also found in non-gonadal somatic contexts. Moreover, these pathways have also been reported in bacteria, mollusks and arthropods, associated with safeguard of genomes against transposable elements, regulation of gene expression and with direct consequences in axon regeneration and memory formation. In this Perspective we draw attention to early branching parasitic protozoa, whose genome preservation is an essential function as in late eukaryotes. However, little is known about the defense mechanisms of these genomes. We and others have described the presence of putative PIWI-related machinery members in protozoan parasites. We have described the presence of a PIWI-like protein in Trypanosoma cruzi, bound to small non-coding RNAs (sRNAs) as cargo of secreted extracellular vesicles relevant in intercellular communication and host infection. Herein, we put forward the presence of members related to Argonaute pathways in both Trypanosoma cruzi and Toxoplasma gondii. The presence of PIWI-like machinery in Trypansomatids and Apicomplexa, respectively, could be evidence of an ancestral piRNA machinery that evolved to become more sophisticated and complex in multicellular eukaryotes. We propose a model in which ancient PIWI proteins were expressed broadly and had functions independent of germline maintenance. A better understanding of current and ancestral PIWI/piRNAs will be relevant to better understand key mechanisms of genome integrity conservation during cell cycle progression and modulation of host defense mechanisms by protozoan parasites.
Collapse
Affiliation(s)
- S. Horjales
- Apicomplexa Biology Laboratory, Institute Pasteur Montevideo, Montevideo, Uruguay
| | - M Li Calzi
- Functional Genomics Laboratory, Institute Pasteur Montevideo, Montevideo, Uruguay
| | - M. E. Francia
- Apicomplexa Biology Laboratory, Institute Pasteur Montevideo, Montevideo, Uruguay
- Departamento de Parasitología y Micología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - A. Cayota
- Functional Genomics Laboratory, Institute Pasteur Montevideo, Montevideo, Uruguay
- Departmento Basico de Medicina, Facultad de Medicina, Hospital de Clinicas, Universidad de la República, Montevideo, Uruguay
| | - M. R. Garcia-Silva
- Functional Genomics Laboratory, Institute Pasteur Montevideo, Montevideo, Uruguay
| |
Collapse
|
4
|
Current Status of Regulatory Non-Coding RNAs Research in the Tritryp. Noncoding RNA 2022; 8:ncrna8040054. [PMID: 35893237 PMCID: PMC9326685 DOI: 10.3390/ncrna8040054] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2022] [Revised: 07/01/2022] [Accepted: 07/02/2022] [Indexed: 11/23/2022] Open
Abstract
Trypanosomatids are protozoan parasites that cause devastating vector-borne human diseases. Gene expression regulation of these organisms depends on post-transcriptional control in responding to diverse environments while going through multiple developmental stages of their complex life cycles. In this scenario, non-coding RNAs (ncRNAs) are excellent candidates for a very efficient, quick, and economic strategy to regulate gene expression. The advent of high throughput RNA sequencing technologies show the presence and deregulation of small RNA fragments derived from canonical ncRNAs. This review seeks to depict the ncRNA landscape in trypanosomatids, focusing on the small RNA fragments derived from functional RNA molecules observed in RNA sequencing studies. Small RNA fragments derived from canonical ncRNAs (tsRNAs, snsRNAs, sdRNAs, and sdrRNAs) were identified in trypanosomatids. Some of these RNAs display changes in their levels associated with different environments and developmental stages, demanding further studies to determine their functional characterization and potential roles. Nevertheless, a comprehensive and detailed ncRNA annotation for most trypanosomatid genomes is still needed, allowing better and more extensive comparative and functional studies.
Collapse
|
5
|
Abstract
Abstract
In Trypanosoma brucei and related Kinetoplastids, regulation of gene expression occurs mostly post-transcriptionally, and RNA-binding proteins play a critical role in the regulation of mRNA and protein abundance. Trypanosoma brucei ZC3H28 is a 114 KDa cytoplasmic mRNA-binding protein with a single C(x)7C(x)5C(x)sH zinc finger at the C-terminus and numerous proline-, histidine- or glutamine-rich regions. ZC3H28 is essential for normal bloodstream-form trypanosome growth, and when tethered to a reporter mRNA, ZC3H28 increased reporter mRNA and protein levels. Purification of N-terminally tagged ZC3H28 followed by mass spectrometry showed enrichment of ribosomal proteins, various RNA-binding proteins including both poly(A) binding proteins, the translation initiation complex EIF4E4/EIF4G3, and the activator MKT1. Tagged ZC3H28 was preferentially associated with long RNAs that have low complexity sequences in their 3′-untranslated regions; their coding regions also have low ribosome densities. In agreement with the tethering results, after ZC3H28 depletion, the levels of a significant proportion of its bound mRNAs decreased. We suggest that ZC3H28 is implicated in the stabilization of long mRNAs that are poorly translated.
Collapse
|
6
|
Staneva DP, Carloni R, Auchynnikava T, Tong P, Rappsilber J, Jeyaprakash AA, Matthews KR, Allshire RC. A systematic analysis of Trypanosoma brucei chromatin factors identifies novel protein interaction networks associated with sites of transcription initiation and termination. Genome Res 2021; 31:2138-2154. [PMID: 34407985 PMCID: PMC8559703 DOI: 10.1101/gr.275368.121] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 08/09/2021] [Indexed: 02/07/2023]
Abstract
Nucleosomes composed of histones are the fundamental units around which DNA is wrapped to form chromatin. Transcriptionally active euchromatin or repressive heterochromatin is regulated in part by the addition or removal of histone post-translational modifications (PTMs) by "writer" and "eraser" enzymes, respectively. Nucleosomal PTMs are recognized by a variety of "reader" proteins that alter gene expression accordingly. The histone tails of the evolutionarily divergent eukaryotic parasite Trypanosoma brucei have atypical sequences and PTMs distinct from those often considered universally conserved. Here we identify 65 predicted readers, writers, and erasers of histone acetylation and methylation encoded in the T. brucei genome and, by epitope tagging, systemically localize 60 of them in the parasite's bloodstream form. ChIP-seq shows that 15 candidate proteins associate with regions of RNAPII transcription initiation. Eight other proteins show a distinct distribution with specific peaks at a subset of RNAPII transcription termination regions marked by RNAPIII-transcribed tRNA and snRNA genes. Proteomic analyses identify distinct protein interaction networks comprising known chromatin regulators and novel trypanosome-specific components. Notably, several SET- and Bromo-domain protein networks suggest parallels to RNAPII promoter-associated complexes in conventional eukaryotes. Further, we identify likely components of TbSWR1 and TbNuA4 complexes whose enrichment coincides with the SWR1-C exchange substrate H2A.Z at RNAPII transcription start regions. The systematic approach used provides details of the composition and organization of the chromatin regulatory machinery in T. brucei and establishes a route to explore divergence from eukaryotic norms in an evolutionarily ancient but experimentally accessible eukaryote.
Collapse
Affiliation(s)
- Desislava P Staneva
- Wellcome Centre for Cell Biology and Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
- Institute of Immunology and Infection Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JT, United Kingdom
| | - Roberta Carloni
- Wellcome Centre for Cell Biology and Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
- Institute of Immunology and Infection Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JT, United Kingdom
| | - Tatsiana Auchynnikava
- Wellcome Centre for Cell Biology and Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
| | | | - Juri Rappsilber
- Wellcome Centre for Cell Biology and Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
- Institute of Biotechnology, Technische Universität, 13355 Berlin, Germany
| | - A Arockia Jeyaprakash
- Wellcome Centre for Cell Biology and Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
| | - Keith R Matthews
- Institute of Immunology and Infection Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JT, United Kingdom
| | - Robin C Allshire
- Wellcome Centre for Cell Biology and Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
| |
Collapse
|
7
|
Horn D. Genome-scale RNAi screens in African trypanosomes. Trends Parasitol 2021; 38:160-173. [PMID: 34580035 DOI: 10.1016/j.pt.2021.09.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 08/31/2021] [Accepted: 09/01/2021] [Indexed: 12/11/2022]
Abstract
Genome-scale genetic screens allow researchers to rapidly identify the genes and proteins that impact a particular phenotype of interest. In African trypanosomes, RNA interference (RNAi) knockdown screens have revealed mechanisms underpinning drug resistance, drug transport, prodrug metabolism, quorum sensing, genome replication, and gene expression control. RNAi screening has also been remarkably effective at highlighting promising potential antitrypanosomal drug targets. The first ever RNAi library screen was implemented in African trypanosomes, and genome-scale RNAi screens and other related approaches continue to have a major impact on trypanosomatid research. Here, I review those impacts in terms of both discovery and translation.
Collapse
Affiliation(s)
- David Horn
- The Wellcome Trust Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK.
| |
Collapse
|
8
|
Identification of positive and negative regulators in the stepwise developmental progression towards infectivity in Trypanosoma brucei. Sci Rep 2021; 11:5755. [PMID: 33707699 PMCID: PMC7952579 DOI: 10.1038/s41598-021-85225-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 02/25/2021] [Indexed: 11/17/2022] Open
Abstract
Trypanosoma brucei is a protozoan parasite that causes important human and livestock diseases in sub-Saharan Africa. By overexpressing a single RNA-binding protein, RBP6, in non-infectious procyclics trypanosomes, we previously recapitulated in vitro the events occurring in the tsetse fly vector, namely the development of epimastigotes and infectious, quiescent metacyclic parasites. To identify genes involved in this developmental progression, we individually targeted 86 transcripts by RNAi in the RBP6 overexpression cell line and assessed the loss-of-function phenotypes on repositioning the kinetoplast, an organelle that contains the mitochondrial genome, the expression of BARP or brucei alanine rich protein, a marker for epimastigotes, and metacyclic variant surface glycoprotein. This screen identified 22 genes that positively or negatively regulate the stepwise progression towards infectivity at different stages. Two previously uncharacterized putative nucleic acid binding proteins emerged as potent regulators, namely the cold shock domain-containing proteins CSD1 and CSD2. RNA-Seq data from a selected group of cell lines further revealed that the components of gene expression regulatory networks identified in this study affected the abundance of a subset of transcripts in very similar fashion. Finally, our data suggest a considerable overlap between the genes that regulate the formation of stumpy bloodstream form trypanosomes and the genes that govern the development of metacyclic form parasites.
Collapse
|
9
|
Small RNAs Are Implicated in Regulation of Gene and Transposable Element Expression in the Protist Trichomonas vaginalis. mSphere 2021; 6:6/1/e01061-20. [PMID: 33408230 PMCID: PMC7845603 DOI: 10.1128/msphere.01061-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Trichomoniasis, caused by the protozoan Trichomonas vaginalis, is the most common nonviral sexually transmitted infection in humans. The millions of cases each year have sequelae that may include complications during pregnancy and increased risk of HIV infection. Trichomonas vaginalis is the causative agent of trichomoniasis, the most prevalent nonviral sexually transmitted infection worldwide. Repetitive elements, including transposable elements (TEs) and virally derived repeats, comprise more than half of the ∼160-Mb T. vaginalis genome. An intriguing question is how the parasite controls its potentially lethal complement of mobile elements, which can disrupt transcription of protein-coding genes and genome functions. In this study, we generated high-throughput RNA sequencing (RNA-Seq) and small RNA-Seq data sets in triplicate for the T. vaginalis G3 reference strain and characterized the mRNA and small RNA populations and their mapping patterns along all six chromosomes. Mapping the RNA-Seq transcripts to the genome revealed that the majority of genes predicted within repetitive elements are not expressed. Interestingly, we identified a novel species of small RNA that maps bidirectionally along the chromosomes and is correlated with reduced protein-coding gene expression and reduced RNA-Seq coverage in repetitive elements. This novel small RNA family may play a regulatory role in gene and repetitive element expression. Our results identify a possible small RNA pathway mechanism by which the parasite regulates expression of genes and TEs and raise intriguing questions as to the role repeats may play in shaping T. vaginalis genome evolution and the diversity of small RNA pathways in general. IMPORTANCE Trichomoniasis, caused by the protozoan Trichomonas vaginalis, is the most common nonviral sexually transmitted infection in humans. The millions of cases each year have sequelae that may include complications during pregnancy and increased risk of HIV infection. Given its evident success in this niche, it is paradoxical that T. vaginalis harbors in its genome thousands of transposable elements that have the potential to be extremely detrimental to normal genomic function. In many organisms, transposon expression is regulated by the activity of endogenously expressed short (∼21 to 35 nucleotides [nt]) small RNA molecules that effect gene silencing by targeting mRNAs for degradation or by recruiting epigenetic silencing machinery to locations in the genome. Our research has identified small RNA molecules correlated with reduced expression of T. vaginalis genes and transposons. This suggests that a small RNA pathway is a major contributor to gene expression patterns in the parasite and opens up new avenues for investigation into small RNA biogenesis, function, and diversity.
Collapse
|
10
|
Awuah-Mensah G, McDonald J, Steketee PC, Autheman D, Whipple S, D'Archivio S, Brandt C, Clare S, Harcourt K, Wright GJ, Morrison LJ, Gadelha C, Wickstead B. Reliable, scalable functional genetics in bloodstream-form Trypanosoma congolense in vitro and in vivo. PLoS Pathog 2021; 17:e1009224. [PMID: 33481935 PMCID: PMC7870057 DOI: 10.1371/journal.ppat.1009224] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 02/08/2021] [Accepted: 12/07/2020] [Indexed: 12/13/2022] Open
Abstract
Animal African trypanosomiasis (AAT) is a severe, wasting disease of domestic livestock and diverse wildlife species. The disease in cattle kills millions of animals each year and inflicts a major economic cost on agriculture in sub-Saharan Africa. Cattle AAT is caused predominantly by the protozoan parasites Trypanosoma congolense and T. vivax, but laboratory research on the pathogenic stages of these organisms is severely inhibited by difficulties in making even minor genetic modifications. As a result, many of the important basic questions about the biology of these parasites cannot be addressed. Here we demonstrate that an in vitro culture of the T. congolense genomic reference strain can be modified directly in the bloodstream form reliably and at high efficiency. We describe a parental single marker line that expresses T. congolense-optimized T7 RNA polymerase and Tet repressor and show that minichromosome loci can be used as sites for stable, regulatable transgene expression with low background in non-induced cells. Using these tools, we describe organism-specific constructs for inducible RNA-interference (RNAi) and demonstrate knockdown of multiple essential and non-essential genes. We also show that a minichromosomal site can be exploited to create a stable bloodstream-form line that robustly provides >40,000 independent stable clones per transfection-enabling the production of high-complexity libraries of genome-scale. Finally, we show that modified forms of T. congolense are still infectious, create stable high-bioluminescence lines that can be used in models of AAT, and follow the course of infections in mice by in vivo imaging. These experiments establish a base set of tools to change T. congolense from a technically challenging organism to a routine model for functional genetics and allow us to begin to address some of the fundamental questions about the biology of this important parasite.
Collapse
Affiliation(s)
| | - Jennifer McDonald
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Pieter C. Steketee
- The Roslin Institute, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom
| | - Delphine Autheman
- Cell Surface Signalling Laboratory, Wellcome Sanger Institute, Cambridge, United Kingdom
| | - Sarah Whipple
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Simon D'Archivio
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Cordelia Brandt
- Pathogen Support Team, Wellcome Sanger Institute, Cambridge, United Kingdom
| | - Simon Clare
- Pathogen Support Team, Wellcome Sanger Institute, Cambridge, United Kingdom
| | - Katherine Harcourt
- Pathogen Support Team, Wellcome Sanger Institute, Cambridge, United Kingdom
| | - Gavin J. Wright
- Cell Surface Signalling Laboratory, Wellcome Sanger Institute, Cambridge, United Kingdom
- Department of Biology, Hull York Medical School, York Biomedical Research Institute, University of York, York, United Kingdom
| | - Liam J. Morrison
- The Roslin Institute, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom
| | - Catarina Gadelha
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Bill Wickstead
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| |
Collapse
|
11
|
Vesteg M, Hadariová L, Horváth A, Estraño CE, Schwartzbach SD, Krajčovič J. Comparative molecular cell biology of phototrophic euglenids and parasitic trypanosomatids sheds light on the ancestor of Euglenozoa. Biol Rev Camb Philos Soc 2019; 94:1701-1721. [PMID: 31095885 DOI: 10.1111/brv.12523] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 04/30/2019] [Accepted: 05/02/2019] [Indexed: 01/23/2023]
Abstract
Parasitic trypanosomatids and phototrophic euglenids are among the most extensively studied euglenozoans. The phototrophic euglenid lineage arose relatively recently through secondary endosymbiosis between a phagotrophic euglenid and a prasinophyte green alga that evolved into the euglenid secondary chloroplast. The parasitic trypanosomatids (i.e. Trypanosoma spp. and Leishmania spp.) and the freshwater phototrophic euglenids (i.e. Euglena gracilis) are the most evolutionary distant lineages in the Euglenozoa phylogenetic tree. The molecular and cell biological traits they share can thus be considered as ancestral traits originating in the common euglenozoan ancestor. These euglenozoan ancestral traits include common mitochondrial presequence motifs, respiratory chain complexes containing various unique subunits, a unique ATP synthase structure, the absence of mitochondria-encoded transfer RNAs (tRNAs), a nucleus with a centrally positioned nucleolus, closed mitosis without dissolution of the nuclear membrane and nucleoli, a nuclear genome containing the unusual 'J' base (β-D-glucosyl-hydroxymethyluracil), processing of nucleus-encoded precursor messenger RNAs (pre-mRNAs) via spliced-leader RNA (SL-RNA) trans-splicing, post-transcriptional gene silencing by the RNA interference (RNAi) pathway and the absence of transcriptional regulation of nuclear gene expression. Mitochondrial uridine insertion/deletion RNA editing directed by guide RNAs (gRNAs) evolved in the ancestor of the kinetoplastid lineage. The evolutionary origin of other molecular features known to be present only in either kinetoplastids (i.e. polycistronic transcripts, compaction of nuclear genomes) or euglenids (i.e. monocistronic transcripts, huge genomes, many nuclear cis-spliced introns, polyproteins) is unclear.
Collapse
Affiliation(s)
- Matej Vesteg
- Department of Biology and Ecology, Faculty of Natural Sciences, Matej Bel University, 974 01, Banská Bystrica, Slovakia
| | - Lucia Hadariová
- Biotechnology and Biomedicine Center of the Academy of Sciences and Charles University in Vestec (BIOCEV), 252 50, Vestec, Czech Republic.,Department of Parasitology, Faculty of Science, Charles University in Prague, 128 44, Prague, Czech Republic
| | - Anton Horváth
- Department of Biochemistry, Faculty of Natural Sciences, Comenius University, 842 15, Bratislava, Slovakia
| | - Carlos E Estraño
- Department of Biological Sciences, University of Memphis, Memphis, TN, 38152-3560, USA
| | - Steven D Schwartzbach
- Department of Biological Sciences, University of Memphis, Memphis, TN, 38152-3560, USA
| | - Juraj Krajčovič
- Department of Biology, Faculty of Natural Sciences, University of ss. Cyril and Methodius, 917 01, Trnava, Slovakia
| |
Collapse
|
12
|
Ferrareze PAG, Streit RSA, Dos Santos FM, Schrank A, Kmetzsch L, Vainstein MH, Staats CC. sRNAs as possible regulators of retrotransposon activity in Cryptococcus gattii VGII. BMC Genomics 2017; 18:294. [PMID: 28403818 PMCID: PMC5389150 DOI: 10.1186/s12864-017-3688-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 04/06/2017] [Indexed: 01/31/2023] Open
Abstract
Background The absence of Argonaute genes in the fungal pathogen Cryptococcus gattii R265 and other VGII strains indicates that yeasts of this genotype cannot have a functional RNAi pathway, an evolutionarily conserved gene silencing mechanism performed by small RNAs. The success of the R265 strain as a pathogen that caused the Pacific Northwest and Vancouver Island outbreaks may imply that RNAi machinery loss could be beneficial under certain circumstances during evolution. As a result, a hypermutant phenotype would be created with high rates of genome retrotransposition, for instance. This study therefore aimed to evaluate in silicio the effect of retrotransposons and their control mechanisms by small RNAs on genomic stability and synteny loss of C. gattii R265 through retrotransposons sequence comparison and orthology analysis with other 16 C. gattii genomic sequences available. Results Retrotransposon mining identified a higher sequence count to VGI genotype compared to VGII, VGIII, and VGIV. However, despite the lower retrotransposon number, VGII exhibited increased synteny loss and genome rearrangement events. RNA-Seq analysis indicated highly expressed retrotransposons as well as sRNA production. Conclusions Genome rearrangement and synteny loss may suggest a greater retrotransposon mobilization caused by RNAi pathway absence, but the effective presence of sRNAs that matches retrotransposon sequences means that an alternative retrotransposon silencing mechanism could be active in genomic integrity maintenance of C. gattii VGII strains. Electronic supplementary material The online version of this article (doi:10.1186/s12864-017-3688-4) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Patrícia Aline Gröhs Ferrareze
- Programa de Pós-Graduação em Biologia Celular e Molecular, Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul (UFRGS), 91501-970, Porto Alegre, RS, Brazil
| | - Rodrigo Silva Araujo Streit
- Departamento de Biologia Molecular e Biotecnologia, Instituto de Biociências, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
| | - Francine Melise Dos Santos
- Programa de Pós-Graduação em Biologia Celular e Molecular, Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul (UFRGS), 91501-970, Porto Alegre, RS, Brazil
| | - Augusto Schrank
- Programa de Pós-Graduação em Biologia Celular e Molecular, Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul (UFRGS), 91501-970, Porto Alegre, RS, Brazil.,Departamento de Biologia Molecular e Biotecnologia, Instituto de Biociências, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
| | - Livia Kmetzsch
- Programa de Pós-Graduação em Biologia Celular e Molecular, Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul (UFRGS), 91501-970, Porto Alegre, RS, Brazil.,Departamento de Biologia Molecular e Biotecnologia, Instituto de Biociências, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
| | - Marilene Henning Vainstein
- Programa de Pós-Graduação em Biologia Celular e Molecular, Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul (UFRGS), 91501-970, Porto Alegre, RS, Brazil.,Departamento de Biologia Molecular e Biotecnologia, Instituto de Biociências, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
| | - Charley Christian Staats
- Programa de Pós-Graduação em Biologia Celular e Molecular, Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul (UFRGS), 91501-970, Porto Alegre, RS, Brazil. .,Departamento de Biologia Molecular e Biotecnologia, Instituto de Biociências, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil.
| |
Collapse
|
13
|
The Evolutionary Loss of RNAi Key Determinants in Kinetoplastids as a Multiple Sporadic Phenomenon. J Mol Evol 2017; 84:104-115. [PMID: 28210761 DOI: 10.1007/s00239-017-9780-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 01/28/2017] [Indexed: 12/11/2022]
Abstract
We screened the genomes of a broad panel of kinetoplastid protists for genes encoding proteins associated with the RNA interference (RNAi) system using probes from the Argonaute (AGO1), Dicer1 (DCL1), and Dicer2 (DCL2) genes of Leishmania brasiliensis and Crithidia fasciculata. We identified homologs for all the three of these genes in the genomes of a subset of these organisms. However, several of these organisms lacked evidence for any of these genes, while others lacked only DCL2. The open reading frames encoding these putative proteins were structurally analyzed in silico. The alignments indicated that the genes are homologous with a high degree of confidence, and three-dimensional structural models strongly supported a functional relationship to previously characterized AGO1, DCL1, and DCL2 proteins. Phylogenetic analysis of these putative proteins showed that these genes, when present, evolved in parallel with other nuclear genes, arguing that the RNAi system genes share a common progenitor, likely across all Kinetoplastea. In addition, the genome segments bearing these genes are highly conserved and syntenic, even among those taxa in which they are absent. However, taxa in which these genes are apparently absent represent several widely divergent branches of kinetoplastids, arguing that these genes were independently lost at least six times in the evolutionary history of these organisms. The mechanisms responsible for the apparent coordinate loss of these RNAi system genes independently in several lineages of kinetoplastids, while being maintained in other related lineages, are currently unknown.
Collapse
|
14
|
Burroughs AM, Aravind L. RNA damage in biological conflicts and the diversity of responding RNA repair systems. Nucleic Acids Res 2016; 44:8525-8555. [PMID: 27536007 PMCID: PMC5062991 DOI: 10.1093/nar/gkw722] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 08/08/2016] [Indexed: 12/16/2022] Open
Abstract
RNA is targeted in biological conflicts by enzymatic toxins or effectors. A vast diversity of systems which repair or ‘heal’ this damage has only recently become apparent. Here, we summarize the known effectors, their modes of action, and RNA targets before surveying the diverse systems which counter this damage from a comparative genomics viewpoint. RNA-repair systems show a modular organization with extensive shuffling and displacement of the constituent domains; however, a general ‘syntax’ is strongly maintained whereby systems typically contain: a RNA ligase (either ATP-grasp or RtcB superfamilies), nucleotidyltransferases, enzymes modifying RNA-termini for ligation (phosphatases and kinases) or protection (methylases), and scaffold or cofactor proteins. We highlight poorly-understood or previously-uncharacterized repair systems and components, e.g. potential scaffolding cofactors (Rot/TROVE and SPFH/Band-7 modules) with their respective cognate non-coding RNAs (YRNAs and a novel tRNA-like molecule) and a novel nucleotidyltransferase associating with diverse ligases. These systems have been extensively disseminated by lateral transfer between distant prokaryotic and microbial eukaryotic lineages consistent with intense inter-organismal conflict. Components have also often been ‘institutionalized’ for non-conflict roles, e.g. in RNA-splicing and in RNAi systems (e.g. in kinetoplastids) which combine a distinct family of RNA-acting prim-pol domains with DICER-like proteins.
Collapse
Affiliation(s)
- A Maxwell Burroughs
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| | - L Aravind
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| |
Collapse
|
15
|
Abstract
Schistosomiasis is a neglected tropical disease responsible for the death of more than 300,000 people every year. The disease is caused by intravascular parasitic platyhelminths called schistosomes. Treatment and control of schistosomiasis rely on a single drug, praziquantel, and concern exists over the possible emergence of resistance to this drug. The recent completion of the genome sequences of the three main worm species that cause schistosomiasis in humans has raised hope for the development of new interventions to treat the disease. RNA interference (RNAi), a mechanism by which gene-specific double-stranded RNA (dsRNA) triggers degradation of homologous mRNA transcripts, has emerged as an important tool to evaluate and validate new potential drug targets. In addition, RNAi has been used to explore the basic biology of these debilitating parasites. RNAi can be achieved in all stages of the parasite's life cycle in which it has been tested. In this review, we describe methods for applying RNAi to suppress gene expression in the intra-mammalian life stages (adults and schistosomula) of Schistosoma mansoni. We describe procedures for isolating and culturing the parasites, preparing and delivering dsRNA targeting a specific gene, as well as a procedure to evaluate gene suppression by quantitative real-time PCR.
Collapse
|
16
|
Miltonprabu S, Muthumani M. Dimethoxycurcumin potentially protects arsenic induced oxidative hepatic injury, inflammation and apoptosis via Nrf2-Keap1 signaling in rats. ACTA ACUST UNITED AC 2014. [DOI: 10.1016/j.bionut.2014.08.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
|
17
|
Stoco PH, Wagner G, Talavera-Lopez C, Gerber A, Zaha A, Thompson CE, Bartholomeu DC, Lückemeyer DD, Bahia D, Loreto E, Prestes EB, Lima FM, Rodrigues-Luiz G, Vallejo GA, Filho JFDS, Schenkman S, Monteiro KM, Tyler KM, de Almeida LGP, Ortiz MF, Chiurillo MA, de Moraes MH, Cunha ODL, Mendonça-Neto R, Silva R, Teixeira SMR, Murta SMF, Sincero TCM, Mendes TADO, Urmenyi TP, Silva VG, DaRocha WD, Andersson B, Romanha ÁJ, Steindel M, de Vasconcelos ATR, Grisard EC. Genome of the avirulent human-infective trypanosome--Trypanosoma rangeli. PLoS Negl Trop Dis 2014; 8:e3176. [PMID: 25233456 PMCID: PMC4169256 DOI: 10.1371/journal.pntd.0003176] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2013] [Accepted: 08/08/2014] [Indexed: 11/25/2022] Open
Abstract
Background Trypanosoma rangeli is a hemoflagellate protozoan parasite infecting humans and other wild and domestic mammals across Central and South America. It does not cause human disease, but it can be mistaken for the etiologic agent of Chagas disease, Trypanosoma cruzi. We have sequenced the T. rangeli genome to provide new tools for elucidating the distinct and intriguing biology of this species and the key pathways related to interaction with its arthropod and mammalian hosts. Methodology/Principal Findings The T. rangeli haploid genome is ∼24 Mb in length, and is the smallest and least repetitive trypanosomatid genome sequenced thus far. This parasite genome has shorter subtelomeric sequences compared to those of T. cruzi and T. brucei; displays intraspecific karyotype variability and lacks minichromosomes. Of the predicted 7,613 protein coding sequences, functional annotations could be determined for 2,415, while 5,043 are hypothetical proteins, some with evidence of protein expression. 7,101 genes (93%) are shared with other trypanosomatids that infect humans. An ortholog of the dcl2 gene involved in the T. brucei RNAi pathway was found in T. rangeli, but the RNAi machinery is non-functional since the other genes in this pathway are pseudogenized. T. rangeli is highly susceptible to oxidative stress, a phenotype that may be explained by a smaller number of anti-oxidant defense enzymes and heat-shock proteins. Conclusions/Significance Phylogenetic comparison of nuclear and mitochondrial genes indicates that T. rangeli and T. cruzi are equidistant from T. brucei. In addition to revealing new aspects of trypanosome co-evolution within the vertebrate and invertebrate hosts, comparative genomic analysis with pathogenic trypanosomatids provides valuable new information that can be further explored with the aim of developing better diagnostic tools and/or therapeutic targets. Comparative genomics is a powerful tool that affords detailed study of the genetic and evolutionary basis for aspects of lifecycles and pathologies caused by phylogenetically related pathogens. The reference genome sequences of three trypanosomatids, T. brucei, T. cruzi and L. major, and subsequent addition of multiple Leishmania and Trypanosoma genomes has provided data upon which large-scale investigations delineating the complex systems biology of these human parasites has been built. Here, we compare the annotated genome sequence of T. rangeli strain SC-58 to available genomic sequence and annotation data from related species. We provide analysis of gene content, genome architecture and key characteristics associated with the biology of this non-pathogenic trypanosome. Moreover, we report striking new genomic features of T. rangeli compared with its closest relative, T. cruzi, such as (1) considerably less amplification on the gene copy number within multigene virulence factor families such as MASPs, trans-sialidases and mucins; (2) a reduced repertoire of genes encoding anti-oxidant defense enzymes; and (3) the presence of vestigial orthologs of the RNAi machinery, which are insufficient to constitute a functional pathway. Overall, the genome of T. rangeli provides for a much better understanding of the identity, evolution, regulation and function of trypanosome virulence determinants for both mammalian host and insect vector.
Collapse
Affiliation(s)
- Patrícia Hermes Stoco
- Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, Brazil
- * E-mail: (PHS); (ECG)
| | - Glauber Wagner
- Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, Brazil
- Universidade do Oeste de Santa Catarina, Joaçaba, Santa Catarina, Brazil
| | - Carlos Talavera-Lopez
- Department of Cell and Molecular Biology, Science for Life Laboratory, Karolinska Institutet, Stockholm, Sweden
| | - Alexandra Gerber
- Laboratório Nacional de Computação Científica, Petrópolis, Rio de Janeiro, Brazil
| | - Arnaldo Zaha
- Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
| | | | | | | | - Diana Bahia
- Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
- Universidade Federal de São Paulo - Escola Paulista de Medicina, São Paulo, São Paulo, Brazil
| | - Elgion Loreto
- Universidade Federal de Santa Maria, Santa Maria, Rio Grande do Sul, Brazil
| | | | - Fábio Mitsuo Lima
- Universidade Federal de São Paulo - Escola Paulista de Medicina, São Paulo, São Paulo, Brazil
| | | | | | | | - Sérgio Schenkman
- Universidade Federal de São Paulo - Escola Paulista de Medicina, São Paulo, São Paulo, Brazil
| | | | - Kevin Morris Tyler
- Biomedical Research Centre, School of Medicine, Health Policy and Practice, University of East Anglia, Norwich, United Kingdom
| | | | - Mauro Freitas Ortiz
- Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
| | - Miguel Angel Chiurillo
- Universidade Federal de São Paulo - Escola Paulista de Medicina, São Paulo, São Paulo, Brazil
- Universidad Centroccidental Lisandro Alvarado, Barquisimeto, Venezuela
| | | | | | | | - Rosane Silva
- Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | | | | | | | | | - Turán Peter Urmenyi
- Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | | | | | - Björn Andersson
- Department of Cell and Molecular Biology, Science for Life Laboratory, Karolinska Institutet, Stockholm, Sweden
| | - Álvaro José Romanha
- Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, Brazil
| | - Mário Steindel
- Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, Brazil
| | | | - Edmundo Carlos Grisard
- Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, Brazil
- * E-mail: (PHS); (ECG)
| |
Collapse
|
18
|
Ericson M, Janes MA, Butter F, Mann M, Ullu E, Tschudi C. On the extent and role of the small proteome in the parasitic eukaryote Trypanosoma brucei. BMC Biol 2014; 12:14. [PMID: 24552149 PMCID: PMC3942054 DOI: 10.1186/1741-7007-12-14] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Accepted: 02/06/2014] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Although technical advances in genomics and proteomics research have yielded a better understanding of the coding capacity of a genome, one major challenge remaining is the identification of all expressed proteins, especially those less than 100 amino acids in length. Such information can be particularly relevant to human pathogens, such as Trypanosoma brucei, the causative agent of African trypanosomiasis, since it will provide further insight into the parasite biology and life cycle. RESULTS Starting with 993 T. brucei transcripts, previously shown by RNA-Sequencing not to coincide with annotated coding sequences (CDS), homology searches revealed that 173 predicted short open reading frames in these transcripts are conserved across kinetoplastids with 13 also conserved in representative eukaryotes. Mining mass spectrometry data sets revealed 42 transcripts encoding at least one matching peptide. RNAi-induced down-regulation of these 42 transcripts revealed seven to be essential in insect-form trypanosomes with two also required for the bloodstream life cycle stage. To validate the specificity of the RNAi results, each lethal phenotype was rescued by co-expressing an RNAi-resistant construct of each corresponding CDS. These previously non-annotated essential small proteins localized to a variety of cell compartments, including the cell surface, mitochondria, nucleus and cytoplasm, inferring the diverse biological roles they are likely to play in T. brucei. We also provide evidence that one of these small proteins is required for replicating the kinetoplast (mitochondrial) DNA. CONCLUSIONS Our studies highlight the presence and significance of small proteins in a protist and expose potential new targets to block the survival of trypanosomes in the insect vector and/or the mammalian host.
Collapse
Affiliation(s)
- Megan Ericson
- Department of Epidemiology of Microbial Diseases, School of Public Health, Yale University, New Haven, CT, USA
| | - Michael A Janes
- Department of Epidemiology of Microbial Diseases, School of Public Health, Yale University, New Haven, CT, USA
- Current address: San Francisco General Hospital, Pulmonary & Critical Care, San Francisco, CA, USA
| | - Falk Butter
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, Martinsried, Germany
- Current address: Institute of Molecular Biology gGmbH, Mainz, Germany
| | - Matthias Mann
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Elisabetta Ullu
- Department of Cell Biology and Internal Medicine, School of Medicine, Yale University, New Haven, CT, USA
| | - Christian Tschudi
- Department of Epidemiology of Microbial Diseases, School of Public Health, Yale University, New Haven, CT, USA
| |
Collapse
|
19
|
Erben E, Chakraborty C, Clayton C. The CAF1-NOT complex of trypanosomes. Front Genet 2014; 4:299. [PMID: 24427169 PMCID: PMC3877767 DOI: 10.3389/fgene.2013.00299] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Accepted: 12/07/2013] [Indexed: 11/13/2022] Open
Abstract
In African trypanosomes, there is no control of transcription initiation by RNA polymerase II at the level of individual protein-coding genes. Transcription is polycistronic, and individual mRNAs are excised by trans-splicing and polyadenylation. As a consequence, trypanosomes are uniquely reliant on post-transcriptional mechanisms for control of gene expression. Rates of mRNA decay vary over up to two orders of magnitude, making these organisms an excellent model system for the study of mRNA degradation processes. The trypanosome CAF1-NOT complex is simpler than that of other organisms, with no CCR4 or NOT4 homolog: it consists of CAF1, NOT1, NOT2, NOT5 NOT9, NOT10, and NOT11. It is important for the initiation of degradation of most, although not all, mRNAs. There is no homolog of NOT4, and Tho and TREX complexes are absent. Functions of the trypanosome NOT complex are therefore likely to be restricted mainly to deadenylation. Mechanisms that cause the NOT complex to deadenylate some mRNAs faster than others must exist, but have not yet been described.
Collapse
Affiliation(s)
- Esteban Erben
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Alliance Heidelberg, Germany
| | - Chaitali Chakraborty
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Alliance Heidelberg, Germany
| | - Christine Clayton
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Alliance Heidelberg, Germany
| |
Collapse
|
20
|
Role of the Trypanosoma brucei HEN1 family methyltransferase in small interfering RNA modification. EUKARYOTIC CELL 2013; 13:77-86. [PMID: 24186950 DOI: 10.1128/ec.00233-13] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Parasitic protozoa of the flagellate order Kinetoplastida represent one of the deepest branches of the eukaryotic tree. Among this group of organisms, the mechanism of RNA interference (RNAi) has been investigated in Trypanosoma brucei and to a lesser degree in Leishmania (Viannia) spp. The pathway is triggered by long double-stranded RNA (dsRNA) and in T. brucei requires a set of five core genes, including a single Argonaute (AGO) protein, T. brucei AGO1 (TbAGO1). The five genes are conserved in Leishmania (Viannia) spp. but are absent in other major kinetoplastid species, such as Trypanosoma cruzi and Leishmania major. In T. brucei small interfering RNAs (siRNAs) are methylated at the 3' end, whereas Leishmania (Viannia) sp. siRNAs are not. Here we report that T. brucei HEN1, an ortholog of the metazoan HEN1 2'-O-methyltransferases, is required for methylation of siRNAs. Loss of TbHEN1 causes a reduction in the length of siRNAs. The shorter siRNAs in hen1(-/-) parasites are single stranded and associated with TbAGO1, and a subset carry a nontemplated uridine at the 3' end. These findings support a model wherein TbHEN1 methylates siRNA 3' ends after they are loaded into TbAGO1 and this methylation protects siRNAs from uridylation and 3' trimming. Moreover, expression of TbHEN1 in Leishmania (Viannia) panamensis did not result in siRNA 3' end methylation, further emphasizing mechanistic differences in the trypanosome and Leishmania RNAi mechanisms.
Collapse
|
21
|
Atayde VD, Shi H, Franklin JB, Carriero N, Notton T, Lye LF, Owens K, Beverley SM, Tschudi C, Ullu E. The structure and repertoire of small interfering RNAs in Leishmania (Viannia) braziliensis reveal diversification in the trypanosomatid RNAi pathway. Mol Microbiol 2012; 87:580-93. [PMID: 23217017 DOI: 10.1111/mmi.12117] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/29/2012] [Indexed: 12/01/2022]
Abstract
Among trypanosomatid protozoa the mechanism of RNA interference (RNAi) has been investigated in Trypanosoma brucei and to a lesser extent in Leishmania braziliensis. Although these two parasitic organisms belong to the same family, they are evolutionarily distantly related raising questions about the conservation of the RNAi pathway. Here we carried out an in-depth analysis of small interfering RNAs (siRNAs) associated with L. braziliensis Argonaute1 (LbrAGO1). In contrast to T. brucei, Leishmania siRNAs are sensitive to 3' end oxidation, indicating the absence of blocking groups, and the Leishmania genome does not code for a HEN1 RNA 2'-O-methyltransferase, which modifies small RNA 3' ends. Consistent with this observation, ~20% of siRNA 3' ends carry non-templated uridines. Thus siRNA biogenesis, and most likely their metabolism, is different in these organisms. Similarly to T. brucei, putative mobile elements and repeats constitute the major Leishmania siRNA-producing loci and AGO1 ablation leads to accumulation of long transcripts derived from putative mobile elements. However, contrary to T. brucei, no siRNAs were detected from other genomic regions with the potential to form double-stranded RNA, namely sites of convergent transcription and inverted repeats. Thus, our results indicate that organism-specific diversification has occurred in the RNAi pathway during evolution of the trypanosomatid lineage.
Collapse
Affiliation(s)
- Vanessa D Atayde
- Departments of Internal Medicine, Yale University, New Haven, CT 06536, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
22
|
Barnard AC, Nijhof AM, Fick W, Stutzer C, Maritz-Olivier C. RNAi in Arthropods: Insight into the Machinery and Applications for Understanding the Pathogen-Vector Interface. Genes (Basel) 2012; 3:702-41. [PMID: 24705082 PMCID: PMC3899984 DOI: 10.3390/genes3040702] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Revised: 10/19/2012] [Accepted: 10/23/2012] [Indexed: 01/06/2023] Open
Abstract
The availability of genome sequencing data in combination with knowledge of expressed genes via transcriptome and proteome data has greatly advanced our understanding of arthropod vectors of disease. Not only have we gained insight into vector biology, but also into their respective vector-pathogen interactions. By combining the strengths of postgenomic databases and reverse genetic approaches such as RNAi, the numbers of available drug and vaccine targets, as well as number of transgenes for subsequent transgenic or paratransgenic approaches, have expanded. These are now paving the way for in-field control strategies of vectors and their pathogens. Basic scientific questions, such as understanding the basic components of the vector RNAi machinery, is vital, as this allows for the transfer of basic RNAi machinery components into RNAi-deficient vectors, thereby expanding the genetic toolbox of these RNAi-deficient vectors and pathogens. In this review, we focus on the current knowledge of arthropod vector RNAi machinery and the impact of RNAi on understanding vector biology and vector-pathogen interactions for which vector genomic data is available on VectorBase.
Collapse
Affiliation(s)
| | - Ard M Nijhof
- Institut für Parasitologie und Tropenveterinärmedizin, Freie Universität Berlin, Königsweg 67, 14163, Berlin, Germany.
| | - Wilma Fick
- Department of Genetics, University of Pretoria, Pretoria, 0002, South Africa.
| | - Christian Stutzer
- Department of Biochemistry, University of Pretoria, Pretoria, 0002, South Africa.
| | | |
Collapse
|
23
|
RETRACTED ARTICLE: Silibinin ameliorates arsenic induced nephrotoxicity by abrogation of oxidative stress, inflammation and apoptosis in rats. Mol Biol Rep 2012; 39:11201-16. [DOI: 10.1007/s11033-012-2029-6] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Accepted: 10/02/2012] [Indexed: 10/27/2022]
|
24
|
Tschudi C, Shi H, Franklin JB, Ullu E. Small interfering RNA-producing loci in the ancient parasitic eukaryote Trypanosoma brucei. BMC Genomics 2012; 13:427. [PMID: 22925482 PMCID: PMC3447711 DOI: 10.1186/1471-2164-13-427] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2012] [Accepted: 08/24/2012] [Indexed: 01/24/2023] Open
Abstract
Background At the core of the RNA interference (RNAi) pathway in Trypanosoma brucei is a single Argonaute protein, TbAGO1, with an established role in controlling retroposon and repeat transcripts. Recent evidence from higher eukaryotes suggests that a variety of genomic sequences with the potential to produce double-stranded RNA are sources for small interfering RNAs (siRNAs). Results To test whether such endogenous siRNAs are present in T. brucei and to probe the individual role of the two Dicer-like enzymes, we affinity purified TbAGO1 from wild-type procyclic trypanosomes, as well as from cells deficient in the cytoplasmic (TbDCL1) or nuclear (TbDCL2) Dicer, and subjected the bound RNAs to Illumina high-throughput sequencing. In wild-type cells the majority of reads originated from two classes of retroposons. We also considerably expanded the repertoire of trypanosome siRNAs to encompass a family of 147-bp satellite-like repeats, many of the regions where RNA polymerase II transcription converges, large inverted repeats and two pseudogenes. Production of these newly described siRNAs is strictly dependent on the nuclear DCL2. Notably, our data indicate that putative centromeric regions, excluding the CIR147 repeats, are not a significant source for endogenous siRNAs. Conclusions Our data suggest that endogenous RNAi targets may be as evolutionarily old as the mechanism itself.
Collapse
Affiliation(s)
- Christian Tschudi
- Department of Internal Medicine, School of Medicine, Yale University, New Haven, CT 06536, USA
| | | | | | | |
Collapse
|
25
|
Identification and characterization of argonaute protein, Ago2 and its associated small RNAs in Schistosoma japonicum. PLoS Negl Trop Dis 2012; 6:e1745. [PMID: 22860145 PMCID: PMC3409120 DOI: 10.1371/journal.pntd.0001745] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Accepted: 06/11/2012] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND The complex life cycle of the genus Schistosoma drives the parasites to employ subtle developmentally dependent gene regulatory machineries. Small non-coding RNAs (sncRNAs) are essential gene regulatory factors that, through their impact on mRNA and genome stability, control stage-specific gene expression. Abundant sncRNAs have been identified in this genus. However, their functionally associated partners, Argonaute family proteins, which are the key components of the RNA-induced silencing complex (RISC), have not yet been fully explored. METHODOLOGY/PRINCIPAL FINDINGS Two monoclonal antibodies (mAbs) specific to Schistosoma japonicum Argonaute protein Ago2 (SjAgo2), but not SjAgo1 and SjAgo3, were generated. Soluble adult worm antigen preparation (SWAP) was subjected to immunoprecipitation with the mAbs and the captured SjAgo2 protein was subsequently confirmed by Western blot and mass spectrometry (MS) analysis. The small RNA population associated with native SjAgo2 in adult parasites was extracted from the immunoprecipitated complex and subjected to library construction. High-through-put sequencing of these libraries yielded a total of ≈50 million high-quality reads. Classification of these small RNAs showed that endogenous siRNAs (endo-siRNAs) generated from transposable elements (TEs), especially from the subclasses of LINE and LTR, were prominent. Further bioinformatics analysis revealed that siRNAs derived from ten types of well-defined retrotransposons were dramatically enriched in the SjAgo2-specific libraries compared to small RNA libraries constructed with total small RNAs from separated adult worms. These results suggest that a key function of SjAgo2 is to maintain genome stability through suppressing the activities of retrotransposons. CONCLUSIONS/SIGNIFICANCE In this study, we identified and characterized one of the three S. japonicum Argonautes, SjAgo2, and its associated small RNAs were found to be predominantly derived from particular classes of retrotransposons. Thus, a major function of SjAgo2 appears to associate with the maintenance of genome stability via suppression of retroelements. The data advance our understanding of the gene regulatory mechanisms in the blood fluke.
Collapse
|
26
|
Barnes RL, Shi H, Kolev NG, Tschudi C, Ullu E. Comparative genomics reveals two novel RNAi factors in Trypanosoma brucei and provides insight into the core machinery. PLoS Pathog 2012; 8:e1002678. [PMID: 22654659 PMCID: PMC3359990 DOI: 10.1371/journal.ppat.1002678] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2011] [Accepted: 03/16/2012] [Indexed: 11/23/2022] Open
Abstract
The introduction ten years ago of RNA interference (RNAi) as a tool for molecular exploration in Trypanosoma brucei has led to a surge in our understanding of the pathogenesis and biology of this human parasite. In particular, a genome-wide RNAi screen has recently been combined with next-generation Illumina sequencing to expose catalogues of genes associated with loss of fitness in distinct developmental stages. At present, this technology is restricted to RNAi-positive protozoan parasites, which excludes T. cruzi, Leishmania major, and Plasmodium falciparum. Therefore, elucidating the mechanism of RNAi and identifying the essential components of the pathway is fundamental for improving RNAi efficiency in T. brucei and for transferring the RNAi tool to RNAi-deficient pathogens. Here we used comparative genomics of RNAi-positive and -negative trypanosomatid protozoans to identify the repertoire of factors in T. brucei. In addition to the previously characterized Argonaute 1 (AGO1) protein and the cytoplasmic and nuclear Dicers, TbDCL1 and TbDCL2, respectively, we identified the RNA Interference Factors 4 and 5 (TbRIF4 and TbRIF5). TbRIF4 is a 3′-5′ exonuclease of the DnaQ superfamily and plays a critical role in the conversion of duplex siRNAs to the single-stranded form, thus generating a TbAGO1-siRNA complex required for target-specific cleavage. TbRIF5 is essential for cytoplasmic RNAi and appears to act as a TbDCL1 cofactor. The availability of the core RNAi machinery in T. brucei provides a platform to gain mechanistic insights in this ancient eukaryote and to identify the minimal set of components required to reconstitute RNAi in RNAi-deficient parasites. RNA interference (RNAi), a naturally-occurring pathway whereby the presence of double-stranded RNA in a cell triggers the degradation of homologous mRNA, has been harnessed in many organisms as an invaluable molecular biology tool to interrogate gene function. Although this technology is widely used in the protozoan parasite Trypanosoma brucei, other parasites of considerable public health significance, such as Trypanosoma cruzi, Leishmania major, and Plasmodium falciparum do not perform RNAi. Since RNAi has recently been introduced into budding yeast, this opens up the possibility that RNAi can be reconstituted in these pathogens. The key to this is getting a handle on the essential RNAi factors in T. brucei. By applying comparative genomics we identified five genes that are present in the RNAi-proficient species, but not in RNAi-deficient species: three previously identified RNAi factors, and two novel ones, which are described here. This insight into the core T. brucei RNAi machinery represents a major step towards transferring this pathway to RNAi-deficient parasites.
Collapse
Affiliation(s)
- Rebecca L. Barnes
- Department of Internal Medicine, Yale University, New Haven, Connecticut, United States of America
| | - Huafang Shi
- Department of Internal Medicine, Yale University, New Haven, Connecticut, United States of America
| | - Nikolay G. Kolev
- Division of Epidemiology of Microbial Diseases, School of Public Health, Yale University, New Haven, Connecticut, United States of America
| | - Christian Tschudi
- Division of Epidemiology of Microbial Diseases, School of Public Health, Yale University, New Haven, Connecticut, United States of America
- * E-mail:
| | - Elisabetta Ullu
- Department of Internal Medicine, Yale University, New Haven, Connecticut, United States of America
- Department of Cell Biology, School of Medicine, Yale University, New Haven, Connecticut, United States of America
| |
Collapse
|
27
|
Musiyenko A, Majumdar T, Andrews J, Adams B, Barik S. PRMT1 methylates the single Argonaute of Toxoplasma gondii and is important for the recruitment of Tudor nuclease for target RNA cleavage by antisense guide RNA. Cell Microbiol 2012; 14:882-901. [PMID: 22309152 DOI: 10.1111/j.1462-5822.2012.01763.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Argonaute (Ago) plays a central role in RNA interference in metazoans, but its status in lower organisms remains ill-defined. We report on the Ago complex of the unicellular protozoan, Toxoplasma gondii (Tg), an obligatory pathogen of mammalian hosts. The PIWI-like domain of TgAgo lacked the canonical DDE/H catalytic triad, explaining its weak target RNA cleavage activity. However, TgAgo associated with a stronger RNA slicer, a Tudor staphylococcal nuclease (TSN), and with a protein Arg methyl transferase, PRMT1. Mutational analysis suggested that the N-terminal RGG-repeat domain of TgAgo was methylated by PRMT1, correlating with the recruitment of TSN. The slicer activity of TgAgo was Mg(2+)-dependent and required perfect complementarity between the guide RNA and the target. In contrast, the TSN activity was Ca(2+) -dependent and required an imperfectly paired guide RNA. Ago knockout parasites showed essentially normal growth, but in contrast, the PRMT1 knockouts grew abnormally. Chemical inhibition of Arg-methylation also had an anti-parasitic effect. These results suggest that the parasitic PRMT1 plays multiple roles, and its loss affects the recruitment of a more potent second slicer to the parasitic RNA silencing complex, the exact mechanism of which remains to be determined.
Collapse
Affiliation(s)
- Alla Musiyenko
- Department of Biochemistry and Molecular Biology, University of South Alabama, College of Medicine, 307 University Blvd., Mobile, Alabama, USA
| | | | | | | | | |
Collapse
|
28
|
Affiliation(s)
- Kaustuv Sanyal
- Molecular Mycology Laboratory, Molecular Biology & Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore, India.
| |
Collapse
|
29
|
Teixeira SM, de Paiva RMC, Kangussu-Marcolino MM, Darocha WD. Trypanosomatid comparative genomics: Contributions to the study of parasite biology and different parasitic diseases. Genet Mol Biol 2012; 35:1-17. [PMID: 22481868 PMCID: PMC3313497 DOI: 10.1590/s1415-47572012005000008] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Accepted: 10/18/2011] [Indexed: 01/23/2023] Open
Abstract
In 2005, draft sequences of the genomes of Trypanosoma brucei, Trypanosoma cruzi and Leishmania major, also known as the Tri-Tryp genomes, were published. These protozoan parasites are the causative agents of three distinct insect-borne diseases, namely sleeping sickness, Chagas disease and leishmaniasis, all with a worldwide distribution. Despite the large estimated evolutionary distance among them, a conserved core of ~6,200 trypanosomatid genes was found among the Tri-Tryp genomes. Extensive analysis of these genomic sequences has greatly increased our understanding of the biology of these parasites and their host-parasite interactions. In this article, we review the recent advances in the comparative genomics of these three species. This analysis also includes data on additional sequences derived from other trypanosmatid species, as well as recent data on gene expression and functional genomics. In addition to facilitating the identification of key parasite molecules that may provide a better understanding of these complex diseases, genome studies offer a rich source of new information that can be used to define potential new drug targets and vaccine candidates for controlling these parasitic infections.
Collapse
Affiliation(s)
- Santuza M Teixeira
- Departamento de Bioquímica e Imunologia, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | | | | | | |
Collapse
|
30
|
Small RNA transcriptome investigation based on next-generation sequencing technology. J Genet Genomics 2011; 38:505-13. [DOI: 10.1016/j.jgg.2011.08.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2011] [Revised: 08/25/2011] [Accepted: 08/25/2011] [Indexed: 12/28/2022]
|
31
|
Delhi P, Queiroz R, Inchaustegui D, Carrington M, Clayton C. Is there a classical nonsense-mediated decay pathway in trypanosomes? PLoS One 2011; 6:e25112. [PMID: 21957477 PMCID: PMC3177853 DOI: 10.1371/journal.pone.0025112] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Accepted: 08/24/2011] [Indexed: 11/18/2022] Open
Abstract
In many eukaryotes, messenger RNAs with premature termination codons are destroyed by a process called "nonsense-mediated decay", which requires the RNA helicase Upf1 and also, usually, an interacting factor, Upf2. Recognition of premature termination codons may rely on their distance from either a splice site or the polyadenylation site, and long 3'-untranslated regions can trigger mRNA decay. The protist Trypanosoma brucei relies heavily on mRNA degradation to determine mRNA levels, and 3'-untranslated regions play a major role in control of mRNA decay. We show here that trypanosomes have a homologue of Upf1, TbUPF1, which interacts with TbUPF2 and (in an RNA-dependent fashion) with poly(A) binding protein 1, PABP1. Introduction of a premature termination codon in either an endogenous gene or a reporter gene decreased mRNA abundance, as expected for nonsense-mediated decay, but a dependence of this effect on TbUPF1 could not be demonstrated, and depletion of TbUPF1 by over 95% had no effect on parasite growth or the mRNA transcriptome. Further investigations of the reporter mRNA revealed that increases in open reading frame length tended to increase mRNA abundance. In contrast, inhibition of translation, either using 5'-secondary structures or by lengthening the 5'-untranslated region, usually decreased reporter mRNA abundance. Meanwhile, changing the length of the 3'-untranslated region had no consistent effect on mRNA abundance. We suggest that in trypanosomes, translation per se may inhibit mRNA decay, and interactions with multiple RNA-binding proteins preclude degradation based on 3'-untranslated region length alone.
Collapse
Affiliation(s)
- Praveen Delhi
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Alliance, Hedielberg, Germany
- * E-mail: (PD); (CC)
| | - Rafael Queiroz
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Alliance, Hedielberg, Germany
| | - Diana Inchaustegui
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Alliance, Hedielberg, Germany
| | - Mark Carrington
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Christine Clayton
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Alliance, Hedielberg, Germany
- * E-mail: (PD); (CC)
| |
Collapse
|
32
|
RNA interference in protozoan parasites: achievements and challenges. EUKARYOTIC CELL 2011; 10:1156-63. [PMID: 21764910 DOI: 10.1128/ec.05114-11] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Protozoan parasites that profoundly affect mankind represent an exceptionally diverse group of organisms, including Plasmodium, Toxoplasma, Entamoeba, Giardia, trypanosomes, and Leishmania. Despite the overwhelming impact of these parasites, there remain many aspects to be discovered about mechanisms of pathogenesis and how these organisms survive in the host. Combined with the ever-increasing availability of sequenced genomes, RNA interference (RNAi), discovered a mere 13 years ago, has enormously facilitated the analysis of gene function, especially in organisms that are not amenable to classical genetic approaches. Here we review the current status of RNAi in studies of parasitic protozoa, with special emphasis on its use as a postgenomic tool.
Collapse
|
33
|
Pseudogene-derived small interference RNAs regulate gene expression in African Trypanosoma brucei. Proc Natl Acad Sci U S A 2011; 108:8345-50. [PMID: 21531904 DOI: 10.1073/pnas.1103894108] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Pseudogenes have been shown to acquire unique regulatory roles from more and more organisms. We report the observation of a cluster of siRNAs derived from pseudogenes of African Trypanosoma brucei using high through-put analysis. We show that these pseudogene-derived siRNAs suppress gene expression through RNA interference. The discovery that siRNAs may originate from pseudogenes and regulate gene expression in a unicellular eukaryote provides insights into the functional roles of pseudogenes and into the origin of noncoding small RNAs.
Collapse
|
34
|
The emerging world of small silencing RNAs in protozoan parasites. Trends Parasitol 2011; 27:321-7. [PMID: 21497553 DOI: 10.1016/j.pt.2011.03.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Revised: 03/15/2011] [Accepted: 03/16/2011] [Indexed: 12/14/2022]
Abstract
A new RNA world has emerged in the past 10 years with the discovery of a plethora of 20- to 30-nucleotide long small RNAs that are involved in various gene silencing mechanisms. These small RNAs have considerably changed our view of the regulation of gene expression in eukaryotic organisms, with a major shift towards epigenetic and post-transcriptional mechanisms. In this article, we focus on the striking diversity of small silencing RNAs that have been identified in several protozoan parasites and their potential biological role.
Collapse
|
35
|
Abstract
It is almost 20 years since genetic manipulation of Trypanosoma cruzi was first reported. In this time, there have been steady improvements in the available vector systems, and the applications of the technology have been extended into new areas. Episomal vectors have been modified to enhance the level of expression of transfected genes and to facilitate the sub-cellular location of their products. Integrative vectors have been adapted to allow the development of inducible expression systems and the construction of vectors which enable genome modification through telomere-associated chromosome fragmentation. The uses of reverse genetic approaches to dissect peroxide metabolism and the mechanisms of drug activity and resistance in T. cruzi are illustrated in this chapter as examples of how the technology has been used to investigate biological function. Although there remains scope to improve the flexibility of these systems, they have made valuable contributions towards exploiting the genome sequence data and providing a greater understanding of parasite biology and the mechanisms of infection.
Collapse
Affiliation(s)
- Martin C Taylor
- Department of Pathogen Molecular Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | | | | |
Collapse
|
36
|
Hain D, Bettencourt BR, Okamura K, Csorba T, Meyer W, Jin Z, Biggerstaff J, Siomi H, Hutvagner G, Lai EC, Welte M, Müller HAJ. Natural variation of the amino-terminal glutamine-rich domain in Drosophila argonaute2 is not associated with developmental defects. PLoS One 2010; 5:e15264. [PMID: 21253006 PMCID: PMC3002974 DOI: 10.1371/journal.pone.0015264] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Accepted: 11/08/2010] [Indexed: 11/20/2022] Open
Abstract
The Drosophila argonaute2 (ago2) gene plays a
major role in siRNA mediated RNA silencing pathways. Unlike mammalian Argonaute
proteins, the Drosophila protein has an unusual amino-terminal
domain made up largely of multiple copies of glutamine-rich repeats (GRRs). We
report here that the ago2 locus produces an alternative
transcript that encodes a putative short isoform without this amino-terminal
domain. Several ago2 mutations previously reported to be null
alleles only abolish expression of the long, GRR-containing isoform. Analysis of
drop out (dop) mutations had previously
suggested that variations in GRR copy number result in defects in RNAi and
embryonic development. However, we find that dop mutations
genetically complement transcript-null alleles of ago2 and that
ago2 alleles with variant GRR copy numbers support normal
development. In addition, we show that the assembly of the central RNAi
machinery, the RISC (RNA induced silencing complex), is unimpaired in embryos
when GRR copy number is altered. In fact, we find that GRR copy number is highly
variable in natural D. melanogaster populations as well as in
laboratory strains. Finally, while many other insects share an extensive,
glutamine-rich Ago2 amino-terminal domain, its primary sequence varies
drastically between species. Our data indicate that GRR variation does not
modulate an essential function of Ago2 and that the amino-terminal domain of
Ago2 is subject to rapid evolution.
Collapse
Affiliation(s)
- Daniel Hain
- Division of Cell and Developmental Biology, College of Life Sciences,
University of Dundee, Dundee, United Kingdom
| | | | - Katsutomo Okamura
- Sloan-Kettering Institute, Department of Developmental Biology, New York,
New York, United States of America
| | - Tibor Csorba
- Wellcome Trust Centre for Gene Regulation and Expression, College of Life
Sciences, University of Dundee, Dundee, United Kingdom
| | - Wibke Meyer
- Institut für Genetik, Heinrich Heine Universität,
Düsseldorf, Germany
| | - Zhigang Jin
- Sloan-Kettering Institute, Department of Developmental Biology, New York,
New York, United States of America
| | | | - Haruhiko Siomi
- Department of Molecular Biology, Keio University School of Medicine,
Tokyo, Japan
| | - Gyorgy Hutvagner
- Wellcome Trust Centre for Gene Regulation and Expression, College of Life
Sciences, University of Dundee, Dundee, United Kingdom
| | - Eric C. Lai
- Sloan-Kettering Institute, Department of Developmental Biology, New York,
New York, United States of America
| | - Michael Welte
- Department of Biology, University of Rochester, Rochester, New York,
United States of America
| | - H.-Arno J. Müller
- Division of Cell and Developmental Biology, College of Life Sciences,
University of Dundee, Dundee, United Kingdom
- * E-mail:
| |
Collapse
|
37
|
Janbon G, Maeng S, Yang DH, Ko YJ, Jung KW, Moyrand F, Floyd A, Heitman J, Bahn YS. Characterizing the role of RNA silencing components in Cryptococcus neoformans. Fungal Genet Biol 2010; 47:1070-80. [PMID: 21067947 DOI: 10.1016/j.fgb.2010.10.005] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2010] [Revised: 10/03/2010] [Accepted: 10/08/2010] [Indexed: 10/18/2022]
Abstract
The RNA interference (RNAi) mediated by homology-dependent degradation of the target mRNA with small RNA molecules plays a key role in controlling transcription and translation processes in a number of eukaryotic organisms. The RNAi machinery is also evolutionarily conserved in a wide variety of fungal species, including pathogenic fungi. To elucidate the physiological functions of the RNAi pathway in Cryptococcus neoformans that causes fungal meningitis, here we performed genetic analyses for genes encoding Argonaute (AGO1 and AGO2), RNA-dependent RNA polymerase (RDP1), and Dicers (DCR1 and DCR2) in both serotype A and D C. neoformans. The present study shows that Ago1, Rdp1, and Dcr2 are the major components of the RNAi process occurring in C. neoformans. However, the RNAi machinery is not involved in regulation of production of two virulence factors (capsule and melanin), sexual differentiation, and diverse stress response. Comparative transcriptome analysis of the serotype A and D RNAi mutants revealed that only modest changes occur in the genome-wide transcriptome profiles when the RNAi process was perturbed. Notably, the serotype D rdp1Δ mutants showed an increase in transcript abundance of active retrotransposons and transposons, such as T2 and T3, the latter of which is a novel serotype D-specific transposon of C. neoformans. In a wild type background both T2 and T3 were found to be weakly active mobile elements, although we found no evidence of Cnl1 retrotransposon mobility. In contrast, all three transposable elements exhibited enhanced mobility in the rdp1Δ mutant strain. In conclusion, the RNAi pathway plays an important role in controlling transposon activity and genome integrity of C. neoformans.
Collapse
Affiliation(s)
- Guilhem Janbon
- Unité des Aspergillus, Institut Pasteur, Paris Cedex 15, France
| | | | | | | | | | | | | | | | | |
Collapse
|
38
|
Lye LF, Owens K, Shi H, Murta SMF, Vieira AC, Turco SJ, Tschudi C, Ullu E, Beverley SM. Retention and loss of RNA interference pathways in trypanosomatid protozoans. PLoS Pathog 2010; 6:e1001161. [PMID: 21060810 PMCID: PMC2965760 DOI: 10.1371/journal.ppat.1001161] [Citation(s) in RCA: 166] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Accepted: 09/23/2010] [Indexed: 01/02/2023] Open
Abstract
RNA interference (RNAi) pathways are widespread in metaozoans but the genes required show variable occurrence or activity in eukaryotic microbes, including many pathogens. While some Leishmania lack RNAi activity and Argonaute or Dicer genes, we show that Leishmania braziliensis and other species within the Leishmania subgenus Viannia elaborate active RNAi machinery. Strong attenuation of expression from a variety of reporter and endogenous genes was seen. As expected, RNAi knockdowns of the sole Argonaute gene implicated this protein in RNAi. The potential for functional genetics was established by testing RNAi knockdown lines lacking the paraflagellar rod, a key component of the parasite flagellum. This sets the stage for the systematic manipulation of gene expression through RNAi in these predominantly diploid asexual organisms, and may also allow selective RNAi-based chemotherapy. Functional evolutionary surveys of RNAi genes established that RNAi activity was lost after the separation of the Leishmania subgenus Viannia from the remaining Leishmania species, a divergence associated with profound changes in the parasite infectious cycle and virulence. The genus Leishmania therefore offers an accessible system for testing hypothesis about forces that may select for the loss of RNAi during evolution, such as invasion by viruses, changes in genome plasticity mediated by transposable elements and gene amplification (including those mediating drug resistance), and/or alterations in parasite virulence. RNAi interference pathways play fundamental roles in eukaryotes and provide important methods for the analysis of gene function. Occasionally RNAi has been lost, precluding its use as a tool, as well as raising the question of what forces could lead to loss of such a key pathway. Genomic and functional studies previously showed that within trypanosomatids protozoans RNAi was absent in both Leishmania major and Trypanosoma cruzi. The genome of L. braziliensis, a member of the early diverging Leishmania subgenus Viannia, retained key genes required for RNAi such as an Argonaute. We demonstrated that in fact L. braziliensis shows strong RNAi activity with reporter and endogenous genes affecting flagellar function. These data suggest that RNAi may be productively applied for functional genomic studies in L. braziliensis. We mapped the evolutionary point at which RNAi was lost in lineage leading to Leishmania and Crithidia, and establish that RNAi must have been lost at least twice in the trypanosomatids, once on the lineage leading to T. cruzi and independently following the divergence of the Viannia subgenus from other Leishmania species. Lastly, we discuss hypotheses concerning the forces leading to the loss of RNAi in Leishmania evolution, including viral invasion, increased genome plasticity, and altered virulence.
Collapse
Affiliation(s)
- Lon-Fye Lye
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Katherine Owens
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Huafang Shi
- Department of Internal Medicine, Yale University Medical School, New Haven, Connecticut, United States of America
| | - Silvane M. F. Murta
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Ana Carolina Vieira
- Department of Biochemistry, University of Kentucky Medical Center, Lexington, Kentucky, United States of America
| | - Salvatore J. Turco
- Department of Biochemistry, University of Kentucky Medical Center, Lexington, Kentucky, United States of America
| | - Christian Tschudi
- Department of Internal Medicine, Yale University Medical School, New Haven, Connecticut, United States of America
- Department of Epidemiology & Public Health, Yale University Medical School, New Haven, Connecticut, United States of America
| | - Elisabetta Ullu
- Department of Internal Medicine, Yale University Medical School, New Haven, Connecticut, United States of America
- Department of Cell Biology, Yale University Medical School, New Haven, Connecticut, United States of America
| | - Stephen M. Beverley
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
- * E-mail:
| |
Collapse
|
39
|
Gupta SK, Hury A, Ziporen Y, Shi H, Ullu E, Michaeli S. Small nucleolar RNA interference in Trypanosoma brucei: mechanism and utilization for elucidating the function of snoRNAs. Nucleic Acids Res 2010; 38:7236-47. [PMID: 20601683 PMCID: PMC2978370 DOI: 10.1093/nar/gkq599] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Expression of dsRNA complementary to small nucleolar RNAs (snoRNAs) in Trypanosoma brucei results in snoRNA silencing, termed snoRNAi. Here, we demonstrate that snoRNAi requires the nuclear TbDCL2 protein, but not TbDCL1, which is involved in RNA interference (RNAi) in the cytoplasm. snoRNAi depends on Argonaute1 (Slicer), and on TbDCL2, suggesting that snoRNA dicing and slicing takes place in the nucleus, and further suggesting that AGO1 is active in nuclear silencing. snoRNAi was next utilized to elucidate the function of an abundant snoRNA, TB11Cs2C2 (92 nt), present in a cluster together with the spliced leader associated RNA (SLA1) and snR30, which are both H/ACA RNAs with special nuclear functions. Using AMT-UV cross-linking and RNaseH cleavage, we provide evidence for the interaction of TB11Cs2C2 with the small rRNAs, srRNA-2 and srRNA-6, which are part of the large subunit (LSU) rRNA. snoRNAi of TB11Cs2C2 resulted in defects in generating srRNA-2 and LSUβ rRNA. This is the first snoRNA described so far to engage in trypanosome-specific processing events.
Collapse
Affiliation(s)
- Sachin Kumar Gupta
- The Mina and Everard Goodman Faculty of Life Sciences and Advanced Materials and Nanotechnology Institute, Bar-Ilan University, Ramat-Gan 52900 Israel
| | | | | | | | | | | |
Collapse
|
40
|
Alsford S, Kemp LE, Kawahara T, Horn D. RNA interference, growth and differentiation appear normal in African trypanosomes lacking Tudor staphylococcal nuclease. Mol Biochem Parasitol 2010; 174:70-3. [PMID: 20558212 PMCID: PMC2935966 DOI: 10.1016/j.molbiopara.2010.06.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2010] [Revised: 06/03/2010] [Accepted: 06/04/2010] [Indexed: 01/12/2023]
Abstract
Ribonucleases play important roles in the RNA interference (RNAi) pathway. The Dicer endonuclease converts double-stranded (ds)RNA into small interfering (si)RNA and the Slicer endonuclease, as a component of the RNA induced silencing complex (RISC), cleaves mRNA. Tudor staphylococcal nuclease (Tudor-SN) is another component of RISC in humans, flies and nematodes and is therefore implicated in the RNAi pathway. Here, we explore the potential role of African trypanosome Tudor-SN in RNAi. First, we assembled tudor-sn null mutants and showed that the gene is dispensable for normal growth and for differentiation. Next, we developed an inducible RNAi reporter system and demonstrated that Tudor-SN is dispensable for RNAi. The kinetics of mRNA knock-down, protein knock-down and protein recovery following inactivation of dsRNA expression are all unperturbed in the absence of Tudor-SN. We conclude that if this nuclease plays a role in the destruction or processing of dsRNA, mRNA or siRNA in the RNAi pathway, it is likely a minor one.
Collapse
Affiliation(s)
| | | | | | - David Horn
- Corresponding author. Tel.: +44 20 7927 2352.
| |
Collapse
|
41
|
Abstract
Long interspersed elements (LINE-1 or L1) are the most active
transposable elements in the human genome. Due to their high copy
number and ability to sponsor retrotransposition of nonautonomous
RNA sequences, unchecked L1 activity can negatively impact the
genome by a number of means. Substantial evidence in lower
eukaryotes demonstrates that the RNA interference (RNAi) machinery
plays a major role in containing transposon activity. Despite
extensive analysis in other eukaryotes, no experimental evidence
has been presented that L1-derived siRNAs exist, or that the RNAi
plays a significant role in restricting L1 activity in the human
genome. This review will present evidence showing a direct role
for RNAi in suppressing the movement of transposable elements in
other eukaryotes, as well as speculate on the role RNAi might play
in protecting the human genome from LINE-1 activity.
Collapse
Affiliation(s)
- Harris S. Soifer
- Beckman Research Institute of the City of Hope, Fox North 2002, 1450 East Duarte Road, Duarte, CA 91010-3011, USA
- *Harris S. Soifer:
| |
Collapse
|
42
|
Fernández-Moya SM, Estévez AM. Posttranscriptional control and the role of RNA-binding proteins in gene regulation in trypanosomatid protozoan parasites. WILEY INTERDISCIPLINARY REVIEWS-RNA 2010; 1:34-46. [PMID: 21956905 DOI: 10.1002/wrna.6] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Trypanosomatids are unicellular eukaryotes responsible for severe diseases in humans. They exhibit a number of remarkable biological phenomena, especially at the RNA level. During their life cycles, they alternate between a mammalian host and an insect vector and undergo profound biochemical and morphological transformations in order to adapt to the different environments they find within one or the other host species. These changes are orchestrated by specific gene expression programs. In contrast to other organisms, trypanosomatids do not regulate RNA polymerase II-dependent transcription initiation. Evidence so far indicates that the main control points in gene expression are mRNA degradation and translation. Recent studies have shown that RNA-binding proteins (RBPs) play a critical role in the developmental regulation of mRNA and protein abundance. RBPs seem to bind to specific subsets of mRNAs encoding functionally related proteins. These ribonucleoprotein complexes may represent posttranscriptional operons or regulons that are able to control the fate of multiple mRNAs simultaneously. We suggest that trypanosomatids transduce environmental signals into mRNA and protein abundance through posttranslational modification of RBPs.
Collapse
Affiliation(s)
- Sandra M Fernández-Moya
- Instituto de Parasitologia y Biomedicina Lopez-Neyra, CSIC, Avenida del Conocimiento, s/n, 18100 Armilla, Granada, Spain
| | | |
Collapse
|
43
|
Thomas MC, Macias F, Alonso C, López MC. The biology and evolution of transposable elements in parasites. Trends Parasitol 2010; 26:350-62. [PMID: 20444649 DOI: 10.1016/j.pt.2010.04.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2009] [Revised: 03/30/2010] [Accepted: 04/01/2010] [Indexed: 12/19/2022]
Abstract
Transposable elements (TEs) are dynamic elements that can reshape host genomes by generating rearrangements with the potential to create or disrupt genes, to shuffle existing genes, and to modulate their patterns of expression. In the genomes of parasites that infect mammals several TEs have been identified that probably have been maintained throughout evolution due to their contribution to gene function and regulation of gene expression. This review addresses how TEs are organized, how they colonize the genomes of mammalian parasites, the functional role these elements play in parasite biology, and the interactions between these elements and the parasite genome.
Collapse
Affiliation(s)
- M Carmen Thomas
- Departamento de Biología Molecular, Instituto de Parasitología y Biomedicina López Neyra - CSIC, Parque Tecnológico de Ciencias de la Salud, 18100 Granada, Spain
| | | | | | | |
Collapse
|
44
|
Lau NC. Small RNAs in the animal gonad: guarding genomes and guiding development. Int J Biochem Cell Biol 2010; 42:1334-47. [PMID: 20227517 DOI: 10.1016/j.biocel.2010.03.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2009] [Accepted: 03/08/2010] [Indexed: 10/19/2022]
Abstract
Germ cells must safeguard, apportion, package, and deliver their genomes with exquisite precision to ensure proper reproduction and embryonic development. Classical genetic approaches have identified many genes controlling animal germ cell development, but only recently have some of these genes been linked to the RNA interference (RNAi) pathway, a gene silencing mechanism centered on small regulatory RNAs. Germ cells contain microRNAs (miRNAs), endogenous siRNAs (endo-siRNAs), and Piwi-interacting RNAs (piRNAs); these are bound by members of the Piwi/Argonaute protein family. piwi genes were known to specify germ cell development, but we now understand that mutations disrupting germline development can also affect small RNA accumulation. Small RNA studies in germ cells have revealed a surprising diversity of regulatory mechanisms and a unifying function for germline genes in controlling the spread of transposable elements. Future challenges will be to understand the production of germline small RNAs and to identify the full breadth of gene regulation by these RNAs. Progress in this area will likely impact biomedical goals of manipulating stem cells and preventing diseases caused by the transposition of mobile DNA elements.
Collapse
Affiliation(s)
- Nelson C Lau
- Department of Biology, Brandeis University, 415 South Street, Waltham, MA 02454, USA.
| |
Collapse
|
45
|
Abstract
African trypanosomes are evolutionary-divergent eukaryotes responsible for sleeping sickness. They duplicate their single flagellum while maintaining the old one, providing a unique model to examine mature and elongating flagella in the same cell. Like in most eukaryotes, the trypanosome flagellum is constructed by addition of novel subunits at its distal end via the action of intraflagellar transport (IFT). Almost all genes encoding IFT proteins and motors are conserved in trypanosomes and related species, with only a few exceptions. A dozen of IFT genes have been functionally investigated in this organism, thanks to the potent reverse genetic tools available. Several alternative techniques to trigger RNAi are accessible, either transient RNAi by transfection of long double-stranded RNA or by generation of clonal cell lines able to express long double-stranded RNA under the control of tetracycline-inducible promoters. In addition, we provide a series of techniques to investigate cellular phenotypes in trypanosomes where expression of IFT genes has been silenced. In this chapter, we describe different methods for tagging and expression of IFT proteins in trypanosomes and for visualizing IFT in live cells.
Collapse
|
46
|
Shi H, Chamond N, Djikeng A, Tschudi C, Ullu E. RNA interference in Trypanosoma brucei: role of the n-terminal RGG domain and the polyribosome association of argonaute. J Biol Chem 2009; 284:36511-36520. [PMID: 19880512 DOI: 10.1074/jbc.m109.073072] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Argonaute proteins (AGOs) are central to RNA interference (RNAi) and related silencing pathways. At the core of the RNAi pathway in the ancient parasitic eukaryote Trypanosoma brucei is a single Argonaute protein, TbAGO1, with an established role in the destruction of potentially harmful retroposon transcripts. One notable feature of TbAGO1 is that a fraction sediments with polyribosomes, and this association is facilitated by an arginine/glycine-rich domain (RGG domain) at the N terminus of the protein. Here we report that reducing the size of the RGG domain and, in particular, mutating all arginine residues severely reduced the association of TbAGO1 with polyribosomes and RNAi-induced cleavage of mRNA. However, these mutations did not change the cellular localization of Argonaute and did not affect the accumulation of single-stranded siRNAs, an essential step in the activation of the RNA-induced silencing complex. We further show that mRNA on polyribosomes can be targeted for degradation, although this alliance is not a pre-requisite. Finally, sequestering tubulin mRNAs from translation with antisense morpholino oligonucleotides reduced the RNAi response indicating that mRNAs not engaged in translation may be less accessible to the RNAi machinery. We conclude that the association of the RNAi machinery and target mRNA on polyribosomes promotes an efficient RNAi response. This mechanism may represent an ancient adaptation to ensure that retroposon transcripts are efficiently destroyed, if they become associated with the translational apparatus.
Collapse
Affiliation(s)
- Huafang Shi
- Department of Internal Medicine, Yale University Medical School, New Haven, Connecticut 06536-8012
| | - Nathalie Chamond
- Department of Internal Medicine, Yale University Medical School, New Haven, Connecticut 06536-8012
| | - Appolinaire Djikeng
- Department of Internal Medicine, Yale University Medical School, New Haven, Connecticut 06536-8012
| | - Christian Tschudi
- Department of Epidemiology and Public Health, Yale University Medical School, New Haven, Connecticut 06536-8012.
| | - Elisabetta Ullu
- Department of Internal Medicine, Yale University Medical School, New Haven, Connecticut 06536-8012; Department of Cell Biology, Yale University Medical School, New Haven, Connecticut 06536-8012
| |
Collapse
|
47
|
Distinct and overlapping roles for two Dicer-like proteins in the RNA interference pathways of the ancient eukaryote Trypanosoma brucei. Proc Natl Acad Sci U S A 2009; 106:17933-8. [PMID: 19815526 DOI: 10.1073/pnas.0907766106] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Trypanosoma brucei is one of the most ancient eukaryotes where RNA interference (RNAi) is operational and is the only single-cell pathogen where RNAi has been extensively studied and used as a tool for functional analyses. Here, we report that the T. brucei RNAi pathway, although relying on a single Argonaute protein (AGO1), is initiated by the activities of two distinct Dicer-like enzymes. Both TbDCL1, a mostly cytoplasmic protein, and the previously undescribed nuclear enzyme TbDCL2 contribute to the biogenesis of siRNAs from retroposons. However, TbDCL2 has a predominant role in generating siRNAs from chromosomal internal repeat transcripts that accumulate at the nucleolus in RNAi-deficient cells and in initiating the endogenous RNAi response against retroposons and repeats alike. Moreover, siRNAs generated by both TbDCL1 and TbDCL2 carry a 5'-monophosphate and a blocked 3' terminus, suggesting that 3' end modification is an ancient trait of siRNAs. We thus propose a model whereby TbDCL2 fuels the T. brucei nuclear RNAi pathway and TbDCL1 patrols the cytoplasm, posttranscriptionally silencing potentially harmful nucleic acid parasites that may access the cytoplasm. Nevertheless, we also provide evidence for cross-talk between the two Dicer-like enzymes, because TbDCL2 is implicated in the generation of 35- to 65-nucleotide intermediate transcripts that appear to be substrates for TbDCL1. Our finding that dcl2KO cells are more sensitive to RNAi triggers than wild-type cells has significant implications for reverse genetic analyses in this important human pathogen.
Collapse
|
48
|
Haenni S, Studer E, Burkard GS, Roditi I. Bidirectional silencing of RNA polymerase I transcription by a strand switch region in Trypanosoma brucei. Nucleic Acids Res 2009; 37:5007-18. [PMID: 19531741 PMCID: PMC2731899 DOI: 10.1093/nar/gkp513] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The procyclin genes in Trypanosoma brucei are transcribed by RNA polymerase I as part of 5–10 kb long polycistronic transcription units on chromosomes VI and X. Each procyclin locus begins with two procyclin genes followed by at least one procyclin-associated gene (PAG). In procyclic (insect midgut) form trypanosomes, PAG mRNA levels are about 100-fold lower than those of procyclins. We show that deletion of PAG1, PAG2 or PAG3 results in increased mRNA levels from downstream genes in the same transcription unit. Nascent RNA analysis revealed that most of the effects are due to increased transcription elongation in the knockouts. Furthermore, transient and stable transfections showed that sequence elements on both strands of PAG1 can inhibit Pol I transcription. Finally, by database mining we identified 30 additional PAG-related sequences that are located almost exclusively at strand switch regions and/or at sites where a change of RNA polymerase type is likely to occur.
Collapse
Affiliation(s)
- Simon Haenni
- Institute of Cell Biology, University of Bern, Bern, Switzerland
| | | | | | | |
Collapse
|
49
|
|
50
|
Claser C, Curcio M, de Mello SM, Silveira EV, Monteiro HP, Rodrigues MM. Silencing cytokeratin 18 gene inhibits intracellular replication of Trypanosoma cruzi in HeLa cells but not binding and invasion of trypanosomes. BMC Cell Biol 2008; 9:68. [PMID: 19087356 PMCID: PMC2636781 DOI: 10.1186/1471-2121-9-68] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2008] [Accepted: 12/17/2008] [Indexed: 12/20/2022] Open
Abstract
Background As an obligatory intracellular parasite, Trypanosoma cruzi, the etiological agent of Chagas' disease, must invade and multiply within mammalian cells. Cytokeratin 18 (CK18) is among the host molecules that have been suggested as a mediator of important events during T. cruzi-host cell interaction. Based on that possibility, we addressed whether RNA interference (RNAi)-mediated down regulation of the CK18 gene could interfere with the parasite life cycle in vitro. HeLa cells transiently transfected with CK18-RNAi had negligible levels of CK18 transcripts, and significantly reduced levels of CK18 protein expression as determined by immunoblotting or immunofluorescence. Results CK18 negative or positive HeLa cells were invaded equally as well by trypomastigotes of different T. cruzi strains. Also, in CK18 negative or positive cells, parasites recruited host cells lysosomes and escaped from the parasitophorous vacuole equally as well. After that, the growth of amastigotes of the Y or CL-Brener strains, was drastically arrested in CK18 RNAi-treated cells. After 48 hours, the number of amastigotes was several times lower in CK18 RNAi-treated cells when compared to control cells. Simultaneous staining of parasites and CK18 showed that in HeLa cells infected with the Y strain both co-localize. Although the amastigote surface protein-2 contains the domain VTVXNVFLYNR previously described to bind to CK18, in several attempts, we failed to detect binding of a recombinant protein to CK-18. Conclusion The study demonstrates that silencing CK18 by transient RNAi, inhibits intracellular multiplication of the Y and CL strain of T. cruzi in HeLa cells, but not trypanosome binding and invasion.
Collapse
Affiliation(s)
- Carla Claser
- Centro Interdisciplinar de Terapia Gênica (CINTERGEN), Universidade Federal de São Paulo-Escola Paulista de Medicina, Rua Mirassol, 207, São Paulo-SP 04044-010, Brazil.
| | | | | | | | | | | |
Collapse
|