1
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RNA-seq reveals that overexpression of TcUBP1 switches the gene expression pattern towards that of the infective form of Trypanosoma cruzi. J Biol Chem 2023; 299:104623. [PMID: 36935010 PMCID: PMC10141520 DOI: 10.1016/j.jbc.2023.104623] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 03/02/2023] [Accepted: 03/03/2023] [Indexed: 03/19/2023] Open
Abstract
Trypanosomes regulate gene expression mainly by using post-transcriptional mechanisms. Key factors responsible for carrying out this regulation are RNA-binding proteins (RBPs), affecting subcellular localization, translation, and/or transcript stability. Trypanosoma cruzi U-rich RBP 1 (TcUBP1) is a small protein that modulates the expression of several surface glycoproteins of the trypomastigote infective stage of the parasite. Its mRNA targets are known but the impact of its overexpression at the transcriptome level in the insect-dwelling epimastigote cells has not yet been investigated. Thus, in the present study, by using a tetracycline-inducible system, we generated a population of TcUBP1-overexpressing parasites and analyzed its effect by RNA-seq methodology. This allowed us to identify 793 up- and 371 down-regulated genes with respect to the wild-type control sample. Among the up-regulated genes, it was possible to identify members coding for the TcS superfamily, MASP, MUCI/II, and protein kinases, whereas among the down-regulated transcripts, we found mainly genes coding for ribosomal, mitochondrial, and synthetic pathway proteins. RNA-seq comparison with two previously published datasets revealed that the expression profile of this TcUBP1-overexpressing replicative epimastigote form resembles the transition to the infective metacyclic trypomastigote stage. We identified novel cis-regulatory elements in the 3'-untranslated region of the affected transcripts and confirmed that UBP1m -a signature TcUBP1 binding element previously characterized in our lab- is enriched in the list of stabilized genes. We can conclude that the overall effect of TcUBP1 overexpression on the epimastigote transcriptome is mainly the stabilization of mRNAs coding for proteins that are important for parasite infection.
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2
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Bishola Tshitenge T, Clayton C. The Trypanosoma brucei RNA-binding protein DRBD18 ensures correct mRNA trans splicing and polyadenylation patterns. RNA (NEW YORK, N.Y.) 2022; 28:1239-1262. [PMID: 35793904 PMCID: PMC9380746 DOI: 10.1261/rna.079258.122] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Accepted: 06/23/2022] [Indexed: 06/15/2023]
Abstract
The parasite Trypanosoma brucei grows as bloodstream forms in mammals, and as procyclic forms in tsetse flies. Transcription is polycistronic, all mRNAs are trans spliced, and polyadenylation sites are defined by downstream splicing signals. Expression regulation therefore depends heavily on post-transcriptional mechanisms. The RNA-binding protein DRBD18 was previously implicated in the export of some mRNAs from the nucleus in procyclic forms. It copurifies the outer ring of the nuclear pore, mRNA export factors and exon-junction-complex proteins. We show that for more than 200 mRNAs, DRBD18 depletion caused preferential accumulation of versions with shortened 3'-untranslated regions, arising from use of polyadenylation sites that were either undetectable or rarely seen in nondepleted cells. The shortened mRNAs were often, but not always, more abundant in depleted cells than the corresponding longer versions in normal cells. Their appearance was linked to the appearance of trans-spliced, polyadenylated RNAs containing only downstream 3'-untranslated region-derived sequences. Experiments with one mRNA suggested that nuclear retention alone, through depletion of MEX67, did not affect mRNA length, suggesting a specific effect of DRBD18 on processing. DRBD18-bound mRNAs were enriched in polypyrimidine tract motifs, and DRBD18 was found in both the nucleus and the cytoplasm. We therefore suggest that in the nucleus, DRBD18 might bind to polypyrimidine tracts in 3'-UTRs of mRNA precursors. Such binding might both prevent recognition of mRNA-internal polypyrimidine tracts by splicing factors, and promote export of the processed bound mRNAs to the cytosol.
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Affiliation(s)
| | - Christine Clayton
- Heidelberg University Center for Molecular Biology (ZMBH), D69120 Heidelberg, Germany
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3
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Abstract
Trypanosoma brucei is unusually reliant on mRNA-binding proteins to control mRNA fate, because its protein-coding genes lack individual promoters. We here focus on three trypanosome RNA-binding proteins. ZC3H22 is specific to Tsetse fly forms, RBP9 is preferentially expressed in bloodstream forms; and DRBD7 is constitutively expressed. Depletion of RBP9 or DRBD7 did not affect bloodstream-form trypanosome growth. ZC3H22 depletion from procyclic forms caused cell clumping, decreased expression of genes required for cell growth and proliferation, and increased expression of some epimastigote markers. Apart from decreases in mRNAs encoding enzymes of glucose metabolism, levels of most ZC3H22-bound transcripts were unaffected by ZC3H22 depletion. We compared ZC3H22, RBP9 and DRBD7 RNA binding with that of 16 other RNA-binding proteins. ZC3H22, PUF3 and ERBP1 show a preference for ribosomal protein mRNAs. RBP9 preferentially binds mRNAs that are more abundant in bloodstream forms than in procyclic forms. RBP9, ZC3H5, ZC3H30 and DRBD7 prefer mRNAs with long coding regions; UBP1-associated mRNAs have long 3′-untranslated regions; and RRM1 prefers mRNAs with long 3′or 5′-untranslated regions. We suggest that proteins that prefer long mRNAs may have relatively short or degenerate binding sites, and that preferences for A or U increase binding in untranslated regions.
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4
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Identification of Novel Interspersed DNA Repetitive Elements in the Trypanosoma cruzi Genome Associated with the 3'UTRs of Surface Multigenic Families. Genes (Basel) 2020; 11:genes11101235. [PMID: 33096822 PMCID: PMC7593948 DOI: 10.3390/genes11101235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 10/12/2020] [Accepted: 10/14/2020] [Indexed: 11/23/2022] Open
Abstract
Trypanosoma cruzi is the etiological agent of Chagas disease, which affects millions of people in Latin America. No transcriptional control of gene expression has been demonstrated in this organism, and 50% of its genome consists of repetitive elements and members of multigenic families. In this study, we applied a novel bioinformatics approach to predict new repetitive elements in the genome sequence of T. cruzi. A new repetitive sequence measuring 241 nt was identified and found to be interspersed along the genome sequence from strains of different DTUs. This new repeat was mostly on intergenic regions, and upstream and downstream regions of the 241 nt repeat were enriched in surface protein genes. RNAseq analysis revealed that the repeat was part of processed mRNAs and was predominantly found in the 3′ untranslated regions (UTRs) of genes of multigenic families encoding surface proteins. Moreover, we detected a correlation between the presence of the repeat in the 3′UTR of multigenic family genes and the level of differential expression of these genes when comparing epimastigote and trypomastigote transcriptomes. These data suggest that this sequence plays a role in the posttranscriptional regulation of the expression of multigenic families.
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Herreros-Cabello A, Callejas-Hernández F, Gironès N, Fresno M. Trypanosoma Cruzi Genome: Organization, Multi-Gene Families, Transcription, and Biological Implications. Genes (Basel) 2020; 11:E1196. [PMID: 33066599 PMCID: PMC7602482 DOI: 10.3390/genes11101196] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 10/08/2020] [Accepted: 10/12/2020] [Indexed: 01/20/2023] Open
Abstract
Chagas disease caused by the parasite Trypanosoma cruzi affects millions of people. Although its first genome dates from 2005, its complexity hindered a complete assembly and annotation. However, the new sequencing methods have improved genome annotation of some strains elucidating the broad genetic diversity and complexity of this parasite. Here, we reviewed the genomic structure and regulation, the genetic diversity, and the analysis of the principal multi-gene families of the recent genomes for several strains. The telomeric and sub-telomeric regions are sites with high recombination events, the genome displays two different compartments, the core and the disruptive, and the genome plasticity seems to play a key role in the survival and the infection process. Trypanosoma cruzi (T. cruzi) genome is composed mainly of multi-gene families as the trans-sialidases, mucins, and mucin-associated surface proteins. Trans-sialidases are the most abundant genes in the genome and show an important role in the effectiveness of the infection and the parasite survival. Mucins and MASPs are also important glycosylated proteins of the surface of the parasite that play a major biological role in both insect and mammal-dwelling stages. Altogether, these studies confirm the complexity of T. cruzi genome revealing relevant concepts to better understand Chagas disease.
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Affiliation(s)
- Alfonso Herreros-Cabello
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain; (A.H.-C.); (F.C.-H.)
| | - Francisco Callejas-Hernández
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain; (A.H.-C.); (F.C.-H.)
| | - Núria Gironès
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain; (A.H.-C.); (F.C.-H.)
- Instituto Sanitario de Investigación Princesa, 28006 Madrid, Spain
| | - Manuel Fresno
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain; (A.H.-C.); (F.C.-H.)
- Instituto Sanitario de Investigación Princesa, 28006 Madrid, Spain
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6
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Sabalette KB, Romaniuk MA, Noé G, Cassola A, Campo VA, De Gaudenzi JG. The RNA-binding protein TcUBP1 up-regulates an RNA regulon for a cell surface-associated Trypanosoma cruzi glycoprotein and promotes parasite infectivity. J Biol Chem 2019; 294:10349-10364. [PMID: 31113862 DOI: 10.1074/jbc.ra118.007123] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 05/06/2019] [Indexed: 11/06/2022] Open
Abstract
The regulation of transcription in trypanosomes is unusual. To modulate protein synthesis during their complex developmental stages, these unicellular microorganisms rely largely on post-transcriptional gene expression pathways. These pathways include a plethora of RNA-binding proteins (RBPs) that modulate all steps of the mRNA life cycle in trypanosomes and help organize transcriptomes into clusters of post-transcriptional regulons. The aim of this work was to characterize an RNA regulon comprising numerous transcripts of trypomastigote-associated cell-surface glycoproteins that are preferentially expressed in the infective stages of the human parasite Trypanosoma cruzi. In vitro and in vivo RNA-binding assays disclosed that these glycoprotein mRNAs are targeted by the small trypanosomatid-exclusive RBP in T. cruzi, U-rich RBP 1 (TcUBP1). Overexpression of a GFP-tagged TcUBP1 in replicative parasites resulted in >10 times up-regulated expression of transcripts encoding surface proteins and in changes in their subcellular localization from the posterior region to the perinuclear region of the cytoplasm, as is typically observed in the infective parasite stages. Moreover, RT-quantitative PCR analysis of actively translated mRNAs by sucrose cushion fractionation revealed an increased abundance of these target transcripts in the polysome fraction of TcUBP1-induced samples. Because these surface proteins are involved in cell adherence or invasion during host infection, we also carried out in vitro infections with TcUBP1-transgenic trypomastigotes and observed that TcUBP1 overexpression significantly increases parasite infectivity. Our findings provide evidence for a role of TcUBP1 in trypomastigote stage-specific gene regulation important for T. cruzi virulence.
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Affiliation(s)
- Karina B Sabalette
- From the Instituto de Investigaciones Biotecnológicas, UNSAM-CONICET, 1650 San Martín, Buenos Aires, Argentina
| | - María Albertina Romaniuk
- From the Instituto de Investigaciones Biotecnológicas, UNSAM-CONICET, 1650 San Martín, Buenos Aires, Argentina
| | - Griselda Noé
- From the Instituto de Investigaciones Biotecnológicas, UNSAM-CONICET, 1650 San Martín, Buenos Aires, Argentina
| | - Alejandro Cassola
- From the Instituto de Investigaciones Biotecnológicas, UNSAM-CONICET, 1650 San Martín, Buenos Aires, Argentina
| | - Vanina A Campo
- From the Instituto de Investigaciones Biotecnológicas, UNSAM-CONICET, 1650 San Martín, Buenos Aires, Argentina
| | - Javier G De Gaudenzi
- From the Instituto de Investigaciones Biotecnológicas, UNSAM-CONICET, 1650 San Martín, Buenos Aires, Argentina
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7
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Radío S, Fort RS, Garat B, Sotelo-Silveira J, Smircich P. UTRme: A Scoring-Based Tool to Annotate Untranslated Regions in Trypanosomatid Genomes. Front Genet 2018; 9:671. [PMID: 30619487 PMCID: PMC6305552 DOI: 10.3389/fgene.2018.00671] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Accepted: 12/04/2018] [Indexed: 11/23/2022] Open
Abstract
Most signals involved in post-transcriptional regulatory networks are located in the untranslated regions (UTRs) of the mRNAs. Therefore, to deepen our understanding of gene expression regulation, delimitation of these regions with high accuracy is needed. The trypanosomatid lineage includes a variety of parasitic protozoans causing a significant worldwide burden on human health. Given their peculiar mechanisms of gene expression, these organisms depend on post-transcriptional regulation as the main level of gene expression control. In this context, the definition of the UTR regions becomes of key importance. We have developed UTR-mini-exon (UTRme), a graphical user interface (GUI) stand-alone application to identify and annotate 5′ and 3′ UTR regions in a highly accurate way. UTRme implements a multiple scoring system tailored to address the issue of false positive UTR assignment that frequently arise because of the characteristics of the intergenic regions. Even though it was developed for trypanosomatids, the tool can be used to predict 3′ sites in any eukaryote and 5′ UTRs in any organism where trans-splicing occurs (such as the model organism C. elegans). UTRme offers a way for non-bioinformaticians to precisely determine UTRs from transcriptomic data. The tool is freely available via the conda and github repositories.
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Affiliation(s)
- Santiago Radío
- Department of Genomics, Instituto de Investigaciones Biológicas Clemente Estable, MEC, Montevideo, Uruguay.,Laboratory of Molecular Interactions, Facultad de Ciencias. Universidad de la República, Montevideo, Uruguay
| | - Rafael Sebastián Fort
- Department of Genomics, Instituto de Investigaciones Biológicas Clemente Estable, MEC, Montevideo, Uruguay.,Laboratory of Molecular Interactions, Facultad de Ciencias. Universidad de la República, Montevideo, Uruguay
| | - Beatriz Garat
- Laboratory of Molecular Interactions, Facultad de Ciencias. Universidad de la República, Montevideo, Uruguay
| | - José Sotelo-Silveira
- Department of Genomics, Instituto de Investigaciones Biológicas Clemente Estable, MEC, Montevideo, Uruguay.,Department of Cell and Molecular Biology, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
| | - Pablo Smircich
- Department of Genomics, Instituto de Investigaciones Biológicas Clemente Estable, MEC, Montevideo, Uruguay.,Laboratory of Molecular Interactions, Facultad de Ciencias. Universidad de la República, Montevideo, Uruguay
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8
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Romaniuk MA, Frasch AC, Cassola A. Translational repression by an RNA-binding protein promotes differentiation to infective forms in Trypanosoma cruzi. PLoS Pathog 2018; 14:e1007059. [PMID: 29864162 PMCID: PMC6002132 DOI: 10.1371/journal.ppat.1007059] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2017] [Revised: 06/14/2018] [Accepted: 04/25/2018] [Indexed: 01/08/2023] Open
Abstract
Trypanosomes, protozoan parasites of medical importance, essentially rely on post-transcriptional mechanisms to regulate gene expression in insect vectors and vertebrate hosts. RNA binding proteins (RBPs) that associate to the 3'-UTR of mature mRNAs are thought to orchestrate master developmental programs for these processes to happen. Yet, the molecular mechanisms by which differentiation occurs remain largely unexplored in these human pathogens. Here, we show that ectopic inducible expression of the RBP TcUBP1 promotes the beginning of the differentiation process from non-infective epimastigotes to infective metacyclic trypomastigotes in Trypanosoma cruzi. In early-log epimastigotes TcUBP1 promoted a drop-like phenotype, which is characterized by the presence of metacyclogenesis hallmarks, namely repositioning of the kinetoplast, the expression of an infective-stage virulence factor such as trans-sialidase, increased resistance to lysis by human complement and growth arrest. Furthermore, TcUBP1-ectopic expression in non-infective late-log epimastigotes promoted full development into metacyclic trypomastigotes. TcUBP1-derived metacyclic trypomastigotes were infective in cultured cells, and developed normally into amastigotes in the cytoplasm. By artificial in vivo tethering of TcUBP1 to the 3' untranslated region of a reporter mRNA we were able to determine that translation of the reporter was reduced by 8-fold, while its mRNA abundance was not significantly compromised. Inducible ectopic expression of TcUBP1 confirmed its role as a translational repressor, revealing significant reduction in the translation rate of multiple proteins, a reduction of polysomes, and promoting the formation of mRNA granules. Expression of TcUBP1 truncated forms revealed the requirement of both N and C-terminal glutamine-rich low complexity sequences for the development of the drop-like phenotype in early-log epimastigotes. We propose that a rise in TcUBP1 levels, in synchrony with nutritional deficiency, can promote the differentiation of T. cruzi epimastigotes into infective metacyclic trypomastigotes.
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Affiliation(s)
- Maria Albertina Romaniuk
- Instituto de Investigaciones Biotecnológicas, UNSAM-CONICET, San Martín, Provincia de Buenos Aires, Argentina
| | - Alberto Carlos Frasch
- Instituto de Investigaciones Biotecnológicas, UNSAM-CONICET, San Martín, Provincia de Buenos Aires, Argentina
| | - Alejandro Cassola
- Instituto de Investigaciones Biotecnológicas, UNSAM-CONICET, San Martín, Provincia de Buenos Aires, Argentina
- * E-mail:
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9
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Azizi H, Dumas C, Papadopoulou B. The Pumilio-domain protein PUF6 contributes to SIDER2 retroposon-mediated mRNA decay in Leishmania. RNA (NEW YORK, N.Y.) 2017; 23:1874-1885. [PMID: 28877997 PMCID: PMC5689007 DOI: 10.1261/rna.062950.117] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Accepted: 09/05/2017] [Indexed: 06/07/2023]
Abstract
Leishmania and other trypanosomatid protozoa lack control at the level of transcription initiation and regulate gene expression exclusively post-transcriptionally. We have reported previously that Leishmania harbors a unique class of short interspersed degenerate retroposons (SIDERs) that are predominantly located within 3'UTRs and play a major role in post-transcriptional control. We have shown that members of the SIDER2 subfamily initiate mRNA decay through endonucleolytic cleavage within the second conserved 79-nt signature sequence of SIDER2 retroposons. Here, we have developed an optimized MS2 coat protein tethering system to capture trans-acting factor(s) regulating SIDER2-mediated mRNA decay. Tethering of the MS2 coat protein to a reporter RNA harboring two MS2 stem-loop aptamers and the cognate SIDER2-containing 3'UTR in combination with immunoprecipitation and mass spectrometry analysis led to the identification of RNA-binding proteins with known functions in mRNA decay. Among the candidate SIDER2-interacting proteins that were individually tethered to a SIDER2 reporter RNA, the Pumilio-domain protein PUF6 was shown to enhance degradation and reduce transcript half-life. Furthermore, we showed that PUF6 binds to SIDER2 sequences that include the regulatory 79-nt signature motif, hence contributing to the mRNA decay process. Consistent with a role of PUF6 in SIDER2-mediated decay, genetic inactivation of PUF6 resulted in increased accumulation and higher stability of endogenous SIDER2-bearing transcripts. Overall, these studies provide new insights into regulated mRNA decay pathways in Leishmania controlled by SIDER2 retroposons and propose a broader role for PUF proteins in mRNA decay within the eukaryotic kingdom.
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Affiliation(s)
- Hiva Azizi
- Research Center in Infectious Diseases, CHU de Quebec Research Center-Laval University, Quebec, QC, G1V 4G2 Canada
- Department of Microbiology, Infectious Diseases and Immunology, Faculty of Medicine, Laval University, Quebec, QC, G1V 0A6 Canada
| | - Carole Dumas
- Research Center in Infectious Diseases, CHU de Quebec Research Center-Laval University, Quebec, QC, G1V 4G2 Canada
- Department of Microbiology, Infectious Diseases and Immunology, Faculty of Medicine, Laval University, Quebec, QC, G1V 0A6 Canada
| | - Barbara Papadopoulou
- Research Center in Infectious Diseases, CHU de Quebec Research Center-Laval University, Quebec, QC, G1V 4G2 Canada
- Department of Microbiology, Infectious Diseases and Immunology, Faculty of Medicine, Laval University, Quebec, QC, G1V 0A6 Canada
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10
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Untranslated regions of mRNA and their role in regulation of gene expression in protozoan parasites. J Biosci 2017; 42:189-207. [PMID: 28229978 DOI: 10.1007/s12038-016-9660-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Protozoan parasites are one of the oldest living entities in this world that throughout their existence have shown excellent resilience to the odds of survival and have adapted beautifully to ever changing rigors of the environment. In view of the dynamic environment encountered by them throughout their life cycle, and in establishing pathogenesis, it is unsurprising that modulation of gene expression plays a fundamental role in their survival. In higher eukaryotes, untranslated regions (UTRs) of transcripts are one of the crucial regulators of gene expression (influencing mRNA stability and translation efficiency). Parasitic protozoan genome studies have led to the characterization (in silico, in vitro and in vivo) of a large number of their genes. Comparison of higher eukaryotic UTRs with parasitic protozoan UTRs reveals the existence of several similar and dissimilar facets of the UTRs. This review focuses on the elements of UTRs of medically important protozoan parasites and their regulatory role in gene expression. Such information may be useful to researchers in designing gene targeting strategies linked with perturbation of host-parasite relationships leading to control of specific parasites.
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11
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Polledo JM, Cervini G, Romaniuk MA, Cassola A. Interactions between RNA-binding proteins and P32 homologues in trypanosomes and human cells. Curr Genet 2015; 62:203-12. [PMID: 26385742 DOI: 10.1007/s00294-015-0519-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Revised: 09/09/2015] [Accepted: 09/10/2015] [Indexed: 12/25/2022]
Abstract
RNA-binding proteins (RBPs) are involved in many aspects of mRNA metabolism such as splicing, nuclear export, translation, silencing, and decay. To cope with these tasks, these proteins use specialized domains such as the RNA recognition motif (RRM), the most abundant and widely spread RNA-binding domain. Although this domain was first described as a dedicated RNA-binding moiety, current evidence indicates these motifs can also engage in direct protein-protein interactions. Here, we discuss recent evidence describing the interaction between the RRM of the trypanosomatid RBP UBP1 and P22, the homolog of the human multifunctional protein P32/C1QBP. Human P32 was also identified while performing a similar interaction screening using both RRMs of TDP-43, an RBP involved in splicing regulation and Amyotrophic Lateral Sclerosis. Furthermore, we show that this interaction is mediated by RRM1. The relevance of this interaction is discussed in the context of recent TDP-43 interactomic approaches that identified P32, and the numerous evidences supporting interactions between P32 and RBPs. Finally, we discuss the vast universe of interactions involving P32, supporting its role as a molecular chaperone regulating the function of its ligands.
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Affiliation(s)
- Juan Manuel Polledo
- Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús, UNSAM-CONICET, Buenos Aires, Argentina
| | - Gabriela Cervini
- Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús, UNSAM-CONICET, Buenos Aires, Argentina
| | - María Albertina Romaniuk
- Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús, UNSAM-CONICET, Buenos Aires, Argentina
| | - Alejandro Cassola
- Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús, UNSAM-CONICET, Buenos Aires, Argentina.
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12
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Cassola A, Romaniuk MA, Primrose D, Cervini G, D'Orso I, Frasch AC. Association of UBP1 to ribonucleoprotein complexes is regulated by interaction with the trypanosome ortholog of the human multifunctional P32 protein. Mol Microbiol 2015; 97:1079-96. [PMID: 26096620 DOI: 10.1111/mmi.13090] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/09/2015] [Indexed: 12/30/2022]
Abstract
Regulation of gene expression in trypanosomatid parasitic protozoa is mainly achieved posttranscriptionally. RNA-binding proteins (RBPs) associate to 3' untranslated regions in mRNAs through dedicated domains such as the RNA recognition motif (RRM). Trypanosoma cruzi UBP1 (TcUBP1) is an RRM-type RBP involved in stabilization/degradation of mRNAs. TcUBP1 uses its RRM to associate with cytoplasmic mRNA and to mRNA granules under starvation stress. Here, we show that under starvation stress, TcUBP1 is tightly associated with condensed cytoplasmic mRNA granules. Conversely, under high nutrient/low density-growing conditions, TcUBP1 ribonucleoprotein (RNP) complexes are lax and permeable to mRNA degradation and disassembly. After dissociating from mRNA, TcUBP1 can be phosphorylated only in unstressed parasites. We have identified TcP22, the ortholog of mammalian P32/C1QBP, as an interactor of TcUBP1 RRM. Overexpression of TcP22 decreased the number of TcUBP1 granules in starved parasites in vivo. Endogenous TcUBP1 RNP complexes could be dissociated in vitro by addition of recombinant TcP22, a condition stimulating TcUBP1 phosphorylation. Biochemical and in silico analysis revealed that TcP22 interacts with the RNA-binding surface of TcUBP1 RRM. We propose a model for the decondensation of TcUBP1 RNP complexes in T. cruzi through direct interaction with TcP22 and phosphorylation.
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Affiliation(s)
- Alejandro Cassola
- Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús, UNSAM-CONICET, Buenos Aires, Argentina
| | - María Albertina Romaniuk
- Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús, UNSAM-CONICET, Buenos Aires, Argentina
| | - Debora Primrose
- Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús, UNSAM-CONICET, Buenos Aires, Argentina
| | - Gabriela Cervini
- Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús, UNSAM-CONICET, Buenos Aires, Argentina
| | - Iván D'Orso
- Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús, UNSAM-CONICET, Buenos Aires, Argentina
| | - Alberto Carlos Frasch
- Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús, UNSAM-CONICET, Buenos Aires, Argentina
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13
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Lambertz U, Oviedo Ovando ME, Vasconcelos EJR, Unrau PJ, Myler PJ, Reiner NE. Small RNAs derived from tRNAs and rRNAs are highly enriched in exosomes from both old and new world Leishmania providing evidence for conserved exosomal RNA Packaging. BMC Genomics 2015; 16:151. [PMID: 25764986 PMCID: PMC4352550 DOI: 10.1186/s12864-015-1260-7] [Citation(s) in RCA: 105] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 01/21/2015] [Indexed: 01/09/2023] Open
Abstract
Background Leishmania use exosomes to communicate with their mammalian hosts and these secreted vesicles appear to contribute to pathogenesis by delivering protein virulence factors to macrophages. In other eukaryotes, exosomes were found to carry RNA cargo, such as mRNAs and small non-coding RNAs, capable of altering recipient cell phenotype. Whether leishmania exosomes also contain RNAs which they are able to deliver to bystander cells is not known. Here, we show that leishmania exosomes indeed contain RNAs and compare and contrast the RNA content of exosomes released by Leishmania donovani and Leishmania braziliensis. Results We purified RNA from exosomes collected from axenic amastigote culture supernatant and found that when compared with total leishmania RNA, exosomes mainly contained short RNA sequences. Exosomes with intact membranes were capable of protecting their RNA cargo from degradation by RNase. Moreover, exosome RNA cargo was delivered to host cell cytoplasm in vitro. Sequencing of exosomal RNA indicated that the majority of cargo sequences were derived from non-coding RNA species such as rRNA and tRNA. In depth analysis revealed the presence of tRNA-derived small RNAs, a novel RNA type with suspected regulatory functions. Northern blotting confirmed the specific and selective enrichment of tRNA-derived small RNAs in exosomes. We also identified a number of novel transcripts, which appeared to be specifically enriched in exosomes compared to total cell RNA. In addition, we observed the presence of sequences mapping to siRNA-coding regions in L. braziliensis , but not in L. donovani exosomes. Conclusions These results show that leishmania exosomes are selectively and specifically enriched in small RNAs derived almost exclusively from non-coding RNAs. These exosomes are competent to deliver their cargo of novel, potential small regulatory RNAs to macrophages where they may influence parasite-host cell interactions. The remarkably high degree of congruence in exosomal RNA content between L. donovani and L. braziliensis, argues for the presence of a conserved mechanism for exosomal RNA packaging in leishmania. These findings open up a new avenue of research on non-canonical, small RNA pathways in this trypanosomatid, which may elucidate pathogenesis and identify novel therapeutic approaches. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1260-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ulrike Lambertz
- Departments of Medicine, Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada.
| | - Mariana E Oviedo Ovando
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada.
| | | | - Peter J Unrau
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada.
| | - Peter J Myler
- Seattle Biomedical Research Institute, Seattle, WA, USA. .,Departments of Global Health and Biomedical Informatics & Medical Education, University of Washington, Washington, WA, USA.
| | - Neil E Reiner
- Departments of Medicine, Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada.
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14
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Inoue AH, Serpeloni M, Hiraiwa PM, Yamada-Ogatta SF, Muniz JRC, Motta MCM, Vidal NM, Goldenberg S, Ávila AR. Identification of a novel nucleocytoplasmic shuttling RNA helicase of trypanosomes. PLoS One 2014; 9:e109521. [PMID: 25313564 PMCID: PMC4196910 DOI: 10.1371/journal.pone.0109521] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Accepted: 09/11/2014] [Indexed: 11/18/2022] Open
Abstract
Gene expression in trypanosomes is controlled mostly by post-transcriptional pathways. Little is known about the components of mRNA nucleocytoplasmic export routes in these parasites. Comparative genomics has shown that the mRNA transport pathway is the least conserved pathway among eukaryotes. Nonetheless, we identified a RNA helicase (Hel45) that is conserved across eukaryotes and similar to shuttling proteins involved in mRNA export. We used in silico analysis to predict the structure of Trypanosoma cruzi Hel45, including the N-terminal domain and the C-terminal domain, and our findings suggest that this RNA helicase can form complexes with mRNA. Hel45 was present in both nucleus and cytoplasm. Electron microscopy showed that Hel45 is clustered close to the cytoplasmic side of nuclear pore complexes, and is also present in the nucleus where it is associated with peripheral compact chromatin. Deletion of a predicted Nuclear Export Signal motif led to the accumulation of Hel45ΔNES in the nucleus, indicating that Hel45 shuttles between the nucleus and the cytoplasm. This transport was dependent on active transcription but did not depend on the exportin Crm1. Knockdown of Mex67 in T. brucei caused the nuclear accumulation of the T. brucei ortholog of Hel45. Indeed, Hel45 is present in mRNA ribonucleoprotein complexes that are not associated with polysomes. It is still necessary to confirm the precise function of Hel45. However, this RNA helicase is associated with mRNA metabolism and its nucleocytoplasmic shuttling is dependent on an mRNA export route involving Mex67 receptor.
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Affiliation(s)
| | - Mariana Serpeloni
- Instituto Carlos Chagas, FIOCRUZ, Curitiba, Brazil
- Departamento de Biologia Celular e Molecular, Universidade Federal do Paraná, Curitiba, Brazil
| | | | | | | | - Maria Cristina Machado Motta
- Departamento de Biologia Celular e Parasitologia, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Newton Medeiros Vidal
- Instituto Carlos Chagas, FIOCRUZ, Curitiba, Brazil
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland, United States of America
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15
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Gupta SK, Chikne V, Eliaz D, Tkacz ID, Naboishchikov I, Carmi S, Waldman Ben-Asher H, Michaeli S. Two splicing factors carrying serine-arginine motifs, TSR1 and TSR1IP, regulate splicing, mRNA stability, and rRNA processing in Trypanosoma brucei. RNA Biol 2014; 11:715-31. [PMID: 24922194 DOI: 10.4161/rna.29143] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
In trypanosomes, mRNAs are processed by trans-splicing; in this process, a common exon, the spliced leader, is added to all mRNAs from a small RNA donor, the spliced leader RNA (SL RNA). However, little is known regarding how this process is regulated. In this study we investigated the function of two serine-arginine-rich proteins, TSR1 and TSR1IP, implicated in trans-splicing in Trypanosoma brucei. Depletion of these factors by RNAi suggested their role in both cis- and trans-splicing. Microarray was used to examine the transcriptome of the silenced cells. The level of hundreds of mRNAs was changed, suggesting that these proteins have a role in regulating only a subset of T. brucei mRNAs. Mass-spectrometry analyses of complexes associated with these proteins suggest that these factors function in mRNA stability, translation, and rRNA processing. We further demonstrate changes in the stability of mRNA as a result of depletion of the two TSR proteins. In addition, rRNA defects were observed under the depletion of U2AF35, TSR1, and TSR1IP, but not SF1, suggesting involvement of SR proteins in rRNA processing.
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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, Israel
| | - Vaibhav Chikne
- The Mina and Everard Goodman Faculty of Life Sciences, and Advanced Materials and Nanotechnology Institute; Bar-Ilan University; Ramat-Gan, Israel
| | - Dror Eliaz
- The Mina and Everard Goodman Faculty of Life Sciences, and Advanced Materials and Nanotechnology Institute; Bar-Ilan University; Ramat-Gan, Israel
| | - Itai Dov Tkacz
- The Mina and Everard Goodman Faculty of Life Sciences, and Advanced Materials and Nanotechnology Institute; Bar-Ilan University; Ramat-Gan, Israel
| | - Ilana Naboishchikov
- The Mina and Everard Goodman Faculty of Life Sciences, and Advanced Materials and Nanotechnology Institute; Bar-Ilan University; Ramat-Gan, Israel
| | - Shai Carmi
- The Mina and Everard Goodman Faculty of Life Sciences, and Advanced Materials and Nanotechnology Institute; Bar-Ilan University; Ramat-Gan, Israel
| | - Hiba Waldman Ben-Asher
- The Mina and Everard Goodman Faculty of Life Sciences, and Advanced Materials and Nanotechnology Institute; Bar-Ilan University; Ramat-Gan, Israel
| | - Shulamit Michaeli
- The Mina and Everard Goodman Faculty of Life Sciences, and Advanced Materials and Nanotechnology Institute; Bar-Ilan University; Ramat-Gan, Israel
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16
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Panunzi LG, Agüero F. A genome-wide analysis of genetic diversity in Trypanosoma cruzi intergenic regions. PLoS Negl Trop Dis 2014; 8:e2839. [PMID: 24784238 PMCID: PMC4006747 DOI: 10.1371/journal.pntd.0002839] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Accepted: 03/20/2014] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Trypanosoma cruzi is the causal agent of Chagas Disease. Recently, the genomes of representative strains from two major evolutionary lineages were sequenced, allowing the construction of a detailed genetic diversity map for this important parasite. However this map is focused on coding regions of the genome, leaving a vast space of regulatory regions uncharacterized in terms of their evolutionary conservation and/or divergence. METHODOLOGY Using data from the hybrid CL Brener and Sylvio X10 genomes (from the TcVI and TcI Discrete Typing Units, respectively), we identified intergenic regions that share a common evolutionary ancestry, and are present in both CL Brener haplotypes (TcII-like and TcIII-like) and in the TcI genome; as well as intergenic regions that were conserved in only two of the three genomes/haplotypes analyzed. The genetic diversity in these regions was characterized in terms of the accumulation of indels and nucleotide changes. PRINCIPAL FINDINGS Based on this analysis we have identified i) a core of highly conserved intergenic regions, which remained essentially unchanged in independently evolving lineages; ii) intergenic regions that show high diversity in spite of still retaining their corresponding upstream and downstream coding sequences; iii) a number of defined sequence motifs that are shared by a number of unrelated intergenic regions. A fraction of indels explains the diversification of some intergenic regions by the expansion/contraction of microsatellite-like repeats.
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Affiliation(s)
- Leonardo G. Panunzi
- Instituto de Investigaciones Biotecnológicas – Instituto Tecnológico de Chascomús, Universidad de San Martín – CONICET, Sede San Marítn, Buenos Aires, Argentina
| | - Fernán Agüero
- Instituto de Investigaciones Biotecnológicas – Instituto Tecnológico de Chascomús, Universidad de San Martín – CONICET, Sede San Marítn, Buenos Aires, Argentina
- * E-mail: ;
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17
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da Fonseca Pires S, Fialho LC, Silva SO, Melo MN, de Souza CC, Tafuri WL, Bruna Romero O, de Andrade HM. Identification of virulence factors in Leishmania infantum strains by a proteomic approach. J Proteome Res 2014; 13:1860-72. [PMID: 24617796 DOI: 10.1021/pr400923g] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Knowledge of Leishmania virulence is essential for understanding how the contact between the pathogen and host cells can lead to pathogenesis. Virulence in two L. infantum strains was characterized using macrophages and hamsters. Next, we used difference gel electrophoresis (DIGE) and mass spectrometry to identify the differentially expressed proteins. A total of 63 spots were identified corresponding to 36 proteins; 20 were up-regulated, in which 16 had been previously associated with Leishmania virulence. Considering our results and what has been reported before, we suggest the hypothesis that L. infatum virulence could be a result of the increased expression of KMP-11 and metallopeptidase, associated with an improved parasite-host interacting efficiency and degradation of the protective host proteins and peptides, respectively. Other factors are tryparedoxin peroxidase and peroxidoxin, which protect the parasite against the stress response, and 14-3-3 protein-like, which can prolong infected host cell lifetime. Proteins as chaperones and endoribonuclease L-PSP can increase parasite survival. Enolase is able to perform versatile functions in the cell, acting as a chaperone or in the transcription process, or as a plasminogen receptor or in cell migration events. As expected in more invasive cells with high replication rates, energy consumption and protein synthesis are higher, with up-regulation of Rieske iron-sulfur protein precursor, EF-2, S-adenosylhomocysteine, and phosphomannomutase.
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Affiliation(s)
- Simone da Fonseca Pires
- Departamento de Parasitologia, ‡Departamento de Patologia, and §Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais , 31270-910, Belo Horizonte, Minas Gerais, Brazil
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18
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Kramer S, Carrington M. An AU-rich instability element in the 3'UTR mediates an increase in mRNA stability in response to expression of a dhh1 ATPase mutant. ACTA ACUST UNITED AC 2014; 2:e28587. [PMID: 26779405 PMCID: PMC4705827 DOI: 10.4161/trla.28587] [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: 02/01/2014] [Revised: 03/10/2014] [Accepted: 03/18/2014] [Indexed: 12/11/2022]
Abstract
The DEAD box RNA helicase DHH1 acts as a general repressor of translation and activator of decapping but can also act specifically on individual mRNAs. In trypanosomes, DHH1 overexpression or expression of a dhh1 ATPase mutant, dhh1 DEAD:DQAD, resulted in increased or decreased stability of a small group of mRNAs, mainly encoding developmentally regulated genes. Here, four of the mRNAs affected by dhh1 DEAD:DQAD expression have been analyzed to identify cis-elements involved in dhh1 DEAD:DQAD action. For three mRNAs, the 3′ UTR mediated the change in mRNA level and, in one case, both the 5′ and the 3′ UTR contributed. No responsive elements were detected in the protein coding sequences. One mRNA stabilized by dhh1 DEAD:DQAD expression was analyzed in more detail: deletion or mutation of an AU-rich element in the 3′ UTR resulted in mRNA stabilization in the absence of dhh1 DEAD:DQAD and completely abolished the response to dhh1 DEAD:DQAD. While AU-rich instability elements have been previously shown to mediate mRNA decrease or translational exit by recruitment of DHH1, this is, to our knowledge, the first report of an AU-rich instability element that is responsible for a DHH1 mediated increase in mRNA stability. We suggest a novel model for the selective action of dhh1 on individual mRNAs that is based on the change in the turnover rate of stabilizing or destabilizing RNA binding proteins.
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Affiliation(s)
- Susanne Kramer
- Department of Biochemistry; University of Cambridge; Cambridge, UK
| | - Mark Carrington
- Department of Biochemistry; University of Cambridge; Cambridge, UK
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19
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Adenosine-uridine-rich element is one of the required cis-elements for epimastigote form stage-specific gene expression of the congolense epimastigote specific protein. Mol Biochem Parasitol 2013; 191:36-43. [PMID: 24041588 DOI: 10.1016/j.molbiopara.2013.09.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Revised: 09/04/2013] [Accepted: 09/04/2013] [Indexed: 11/23/2022]
Abstract
It is known that gene expression in kinetoplastida is regulated post-transcriptionally. Several previous studies have shown that stage-specific gene expression in trypanosomes is regulated by cis-elements located in the 3' untranslated region (UTR) of each mRNA and also by RNA binding proteins. Our previous study revealed that gene expression of congolense epimastigote specific protein (cesp) was regulated by cis-elements located in the 3'UTR. In the present study, we identified the adenosine and uridine rich region in the cesp 3'UTR. Using transgenic trypanosome cell lines with different egfp expression cassettes, we showed that this adenosine and uridine rich region is one of the regulatory elements for epimastigote form (EMF) stage-specific gene expression via the regulatory cis-element of the eukaryotic AU rich element (ARE). Therefore this required element within the cesp 3'UTR was designated as T. congolense ARE. This required cis-element might selectively stabilize mRNA in the EMF stage and destabilize mRNA in other stages. By RNA electro mobility shift assay, unknown stage-specific RNA binding proteins (RBPs) whose sequences specifically interacted with the required cis-element were found. These results indicate that EMF stage specific cis-element and RBP complexes might specifically stabilize cesp mRNA in EMF.
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20
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Prestes EB, Bayer-Santos E, Hermes Stoco P, Sincero TCM, Wagner G, Umaki A, Fragoso SP, Bordignon J, Steindel M, Grisard EC. Trypanosoma rangeli protein tyrosine phosphatase is associated with the parasite's flagellum. Mem Inst Oswaldo Cruz 2013; 107:713-9. [PMID: 22990958 DOI: 10.1590/s0074-02762012000600002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Accepted: 05/27/2012] [Indexed: 12/11/2022] Open
Abstract
Protein tyrosine phosphatases (PTPs) play an essential role in the regulation of cell differentiation in pathogenic trypanosomatids. In this study, we describe a PTP expressed by the non-pathogenic protozoan Trypanosoma rangeli (TrPTP2). The gene for this PTP is orthologous to the T. brucei TbPTP1 and Trypanosoma cruzi (TcPTP2) genes. Cloning and expression of the TrPTP2 and TcPTP2 proteins allowed anti-PTP2 monoclonal antibodies to be generated in BALB/c mice. When expressed by T. rangeli epimastigotes and trypomastigotes, native TrPTP2 is detected as a ~65 kDa protein associated with the parasite's flagellum. Given that the flagellum is an important structure for cell differentiation in trypanosomatids, the presence of a protein responsible for tyrosine dephosphorylation in the T. rangeli flagellum could represent an interesting mechanism of regulation in this structure.
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Affiliation(s)
- Elisa Beatriz Prestes
- Laboratórios de Protozoologia e de Bioinformática, Departamento de Microbiologia, Imunologia e Parasitologia, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brasil
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21
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Correa PRC, Cordero EM, Gentil LG, Bayer-Santos E, da Silveira JF. Genetic structure and expression of the surface glycoprotein GP82, the main adhesin of Trypanosoma cruzi metacyclic trypomastigotes. ScientificWorldJournal 2013; 2013:156734. [PMID: 23431251 PMCID: PMC3575623 DOI: 10.1155/2013/156734] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Accepted: 12/30/2012] [Indexed: 01/10/2023] Open
Abstract
T. cruzi improves the likelihood of invading or adapting to the host through its capacity to present a large repertoire of surface molecules. The metacyclic stage-specific surface glycoprotein GP82 has been implicated in host cell invasion. GP82 is encoded by multiple genes from the trans-sialidase superfamily. GP82 shows a modular organization, with some variation of N-terminal region flanking a conserved central core where the binding sites to the mammalian cell and gastric mucin are located. The function of GP82 as adhesin in host cell invasion process could expose the protein to an intense conservative and selective pressure. GP82 is a GPI-anchored surface protein, synthesized as a 70 kDa precursor devoid of N-linked sugars. GPI-minus variants accumulate in the ER indicating that GPI anchor acts as a forward transport signal for progressing along the secretory pathway as suggested for T. cruzi mucins. It has been demonstrated that the expression of GP82 is constitutive and may be regulated at post-transcriptional level, for instance, at translational level and/or mRNA stabilization. GP82 mRNAs are mobilized to polysomes and consequently translated, but only in metacyclic trypomastigotes. Analysis of transgenic parasites indicates that the mechanism regulating GP82 expression involves multiple elements in the 3'UTR.
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Affiliation(s)
- Paulo Roberto Ceridorio Correa
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, Rua Botucatu 862, 04023-062 São Paulo, SP, Brazil
| | - Esteban Mauricio Cordero
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, Rua Botucatu 862, 04023-062 São Paulo, SP, Brazil
| | - Luciana Girotto Gentil
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, Rua Botucatu 862, 04023-062 São Paulo, SP, Brazil
| | - Ethel Bayer-Santos
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, Rua Botucatu 862, 04023-062 São Paulo, SP, Brazil
| | - José Franco da Silveira
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, Rua Botucatu 862, 04023-062 São Paulo, SP, Brazil
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22
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Kramer S, Bannerman-Chukualim B, Ellis L, Boulden EA, Kelly S, Field MC, Carrington M. Differential localization of the two T. brucei poly(A) binding proteins to the nucleus and RNP granules suggests binding to distinct mRNA pools. PLoS One 2013; 8:e54004. [PMID: 23382864 PMCID: PMC3559699 DOI: 10.1371/journal.pone.0054004] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Accepted: 12/06/2012] [Indexed: 12/30/2022] Open
Abstract
The number of paralogs of proteins involved in translation initiation is larger in trypanosomes than in yeasts or many metazoan and includes two poly(A) binding proteins, PABP1 and PABP2, and four eIF4E variants. In many cases, the paralogs are individually essential and are thus unlikely to have redundant functions although, as yet, distinct functions of different isoforms have not been determined. Here, trypanosome PABP1 and PABP2 have been further characterised. PABP1 and PABP2 diverged subsequent to the differentiation of the Kinetoplastae lineage, supporting the existence of specific aspects of translation initiation regulation. PABP1 and PABP2 exhibit major differences in intracellular localization and distribution on polysome fractionation under various conditions that interfere with mRNA metabolism. Most striking are differences in localization to the four known types of inducible RNP granules. Moreover, only PABP2 but not PABP1 can accumulate in the nucleus. Taken together, these observations indicate that PABP1 and PABP2 likely associate with distinct populations of mRNAs. The differences in localization to inducible RNP granules also apply to paralogs of components of the eIF4F complex: eIF4E1 showed similar localization pattern to PABP2, whereas the localisation of eIF4E4 and eIF4G3 resembled that of PABP1. The grouping of translation initiation as either colocalizing with PABP1 or with PABP2 can be used to complement interaction studies to further define the translation initiation complexes in kinetoplastids.
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Affiliation(s)
- Susanne Kramer
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | | | - Louise Ellis
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | | | - Steve Kelly
- Department of Plant Sciences, University of Oxford, and Oxford Centre for Integrative Systems Biology, Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Mark C. Field
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Mark Carrington
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
- * E-mail:
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23
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Bayer-Santos E, Gentil LG, Cordero EM, Corrêa PRC, da Silveira JF. Regulatory elements in the 3' untranslated region of the GP82 glycoprotein are responsible for its stage-specific expression in Trypanosoma cruzi metacyclic trypomastigotes. Acta Trop 2012; 123:230-3. [PMID: 22579673 DOI: 10.1016/j.actatropica.2012.03.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Revised: 03/13/2012] [Accepted: 03/14/2012] [Indexed: 11/29/2022]
Abstract
Gene expression in Trypanosoma cruzi is regulated at the post-transcriptional level and cis-acting elements present in the 3' untranslated region (3'UTR) play an important role by interacting with regulatory proteins. Previous studies demonstrated that the GP82 surface glycoprotein, which is involved in host cell invasion, is up-regulated in the infective metacyclic trypomastigote form, and that GP82 mRNA half-life is longer in this form compared to the non-infective epimastigote form. Here, we demonstrate that the 3'UTR of the GP82 transcript is involved in this developmental regulation, promoting higher expression of the green fluorescent protein (GFP) reporter in metacyclic trypomastigotes than in epimastigotes. A series of stepwise deletions in the 3'UTR was created and results suggest that the mechanism regulating GP82 expression involves multiple elements in the 3'UTR.
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Affiliation(s)
- Ethel Bayer-Santos
- Departamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de São Paulo, UNIFESP, Rua Botucatu 862, CEP 04023-062 São Paulo, Brazil
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24
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dos Santos PF, Ruiz JC, Soares RPP, Moreira DS, Rezende AM, Folador EL, Oliveira G, Romanha AJ, Murta SMF. Molecular characterization of the hexose transporter gene in benznidazole resistant and susceptible populations of Trypanosoma cruzi. Parasit Vectors 2012; 5:161. [PMID: 22871258 PMCID: PMC3431256 DOI: 10.1186/1756-3305-5-161] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Accepted: 08/02/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Hexose transporters (HT) are membrane proteins involved in the uptake of energy-supplying glucose and other hexoses into the cell. Previous studies employing the Differential Display technique have shown that the transcription level of the HT gene from T. cruzi (TcrHT) is higher in an in vitro-induced benznidazole (BZ)-resistant population of the parasite (17 LER) than in its susceptible counterpart (17 WTS). METHODS In the present study, TcrHT has been characterized in populations and strains of T. cruzi that are resistant or susceptible to BZ. We investigated the copy number and chromosomal location of the gene, the levels of TcrHT mRNA and of TcrHT activity, and the phylogenetic relationship between TcrHT and HTs from other organisms. RESULTS In silico analyses revealed that 15 sequences of the TcrHT gene are present in the T. cruzi genome, considering both CL Brener haplotypes. Southern blot analyses confirmed that the gene is present as a multicopy tandem array and indicated a nucleotide sequence polymorphism associated to T. cruzi group I or II. Karyotype analyses revealed that TcrHT is located in two chromosomal bands varying in size from 1.85 to 2.6 Mb depending on the strain of T. cruzi. The sequence of amino acids in the HT from T. cruzi is closely related to the HT sequences of Leishmania species according to phylogenetic analysis. Northern blot and quantitative real-time reverse transcriptase polymerase chain reaction analyses revealed that TcrHT transcripts are 2.6-fold higher in the resistant 17 LER population than in the susceptible 17 WTS. Interestingly, the hexose transporter activity was 40% lower in the 17 LER population than in all other T. cruzi samples analyzed. This phenotype was detected only in the in vitro-induced BZ resistant population, but not in the in vivo-selected or naturally BZ resistant T. cruzi samples. Sequencing analysis revealed that the amino acid sequences of the TcrHT from 17WTS and 17LER populations are identical. This result suggests that the difference in glucose transport between 17WTS and 17LER populations is not due to point mutations, but probably due to lower protein expression level. CONCLUSION The BZ resistant population 17 LER presents a decrease in glucose uptake in response to drug pressure.
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Affiliation(s)
- Paula F dos Santos
- Centro de Pesquisas René Rachou/FIOCRUZ, Avenida Augusto de Lima 1715, Belo Horizonte, 30190-002, MG, Brazil
| | - Jerônimo C Ruiz
- Centro de Pesquisas René Rachou/FIOCRUZ, Avenida Augusto de Lima 1715, Belo Horizonte, 30190-002, MG, Brazil
| | - Rodrigo P P Soares
- Centro de Pesquisas René Rachou/FIOCRUZ, Avenida Augusto de Lima 1715, Belo Horizonte, 30190-002, MG, Brazil
| | - Douglas S Moreira
- Centro de Pesquisas René Rachou/FIOCRUZ, Avenida Augusto de Lima 1715, Belo Horizonte, 30190-002, MG, Brazil
| | - Antônio M Rezende
- Centro de Pesquisas René Rachou/FIOCRUZ, Avenida Augusto de Lima 1715, Belo Horizonte, 30190-002, MG, Brazil
| | - Edson L Folador
- Centro de Pesquisas René Rachou/FIOCRUZ, Avenida Augusto de Lima 1715, Belo Horizonte, 30190-002, MG, Brazil
| | - Guilherme Oliveira
- Centro de Pesquisas René Rachou/FIOCRUZ, Avenida Augusto de Lima 1715, Belo Horizonte, 30190-002, MG, Brazil
- Centro de Excelência em Bioinformática, FIOCRUZ, Rua Araguari 741, Belo Horizonte, 30190-110, MG, Brazil
- Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, 31270-910, MG, Brazil
| | - Alvaro J Romanha
- Centro de Pesquisas René Rachou/FIOCRUZ, Avenida Augusto de Lima 1715, Belo Horizonte, 30190-002, MG, Brazil
| | - Silvane MF Murta
- Centro de Pesquisas René Rachou/FIOCRUZ, Avenida Augusto de Lima 1715, Belo Horizonte, 30190-002, MG, Brazil
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25
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Abstract
Trypanosomatids are protozoan micro-organisms that cause serious health problems in humans and domestic animals. In addition to their medical relevance, these pathogens have novel biological structures and processes. From nuclear DNA transcription to mRNA translation, trypanosomes use unusual mechanisms to control gene expression. For example, transcription by RNAPII (RNA polymerase II) is polycistronic, and only a few transcription initiation sites have been identified so far. The sequences present in the polycistronic units code for proteins having unrelated functions, that is, not involved in a similar metabolic pathway. Owing to these biological constraints, these micro-organisms regulate gene expression mostly by post-transcriptional events. Consequently, the function of proteins that recognize RNA elements preferentially at the 3' UTR (untranslated region) of transcripts is central. It was recently shown that mRNP (messenger ribonucleoprotein) complexes are organized within post-transcriptional operons to co-ordinately regulate gene expression of functionally linked transcripts. In the present chapter we will focus on particular characteristics of gene expression in the so-called TriTryp parasites: Trypanosoma cruzi, Trypanosoma brucei and Leishmania major.
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Wurst M, Seliger B, Jha BA, Klein C, Queiroz R, Clayton C. Expression of the RNA recognition motif protein RBP10 promotes a bloodstream-form transcript pattern in Trypanosoma brucei. Mol Microbiol 2012; 83:1048-63. [PMID: 22296558 DOI: 10.1111/j.1365-2958.2012.07988.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
When Trypanosoma brucei differentiates from the bloodstream form to the procyclic form, there are decreases in the levels of many mRNAs encoding proteins required for the glycolytic pathway, and the mRNA encoding the RNA recognition motif protein RBP10 decreases in parallel. We show that RBP10 is a cytoplasmic protein that is specific to bloodstream-form trypanosomes, where it is essential. Depletion of RBP10 caused decreases in many bloodstream-form-specific mRNAs, with increases in mRNAs associated with the early stages of differentiation. The changes were similar to, but more extensive than, those caused by glucose deprivation. Conversely, forced RBP10 expression in procyclics induced a switch towards bloodstream-form mRNA expression patterns, with concomitant growth inhibition. Forced expression of RBP10 prevented differentiation of bloodstream forms in response to cis-aconitate, but did not prevent expression of key differentiation markers in response to glucose deprivation. RBP10 was not associated with heavy polysomes, showed no detectable in vivo binding to RNA, and was not stably associated with other proteins. Tethering of RBP10 to a reporter mRNA inhibited translation, and halved the abundance of the bound mRNA. We suggest that RBP10 may prevent the expression of regulatory proteins that are specific to the procyclic form.
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Affiliation(s)
- Martin Wurst
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, Heidelberg, Germany
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27
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Teixeira SM, El-Sayed NM, Araújo PR. The genome and its implications. ADVANCES IN PARASITOLOGY 2011; 75:209-30. [PMID: 21820558 DOI: 10.1016/b978-0-12-385863-4.00010-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Trypanosoma cruzi has a heterogeneous population composed of a pool of strains that circulate in the domestic and sylvatic cycles. Genome sequencing of the clone CL Brener revealed a highly repetitive genome of about 110Mb containing an estimated 22,570 genes. Because of its hybrid nature, sequences representing the two haplotypes have been generated. In addition, a repeat content close to 50% made the assembly of the estimated 41 pairs of chromosomes quite challenging. Similar to other trypanosomatids, the organization of T. cruzi chromosomes was found to be very peculiar, with protein-coding genes organized in long polycistronic transcription units encoding 20 or more proteins in one strand separated by strand switch regions. Another remarkable feature of the T. cruzi genome is the massive expansion of surface protein gene families. Because of the high genetic diversity of the T. cruzi population, sequencing of additional strains and comparative genomic and transcriptome analyses are in progress. Five years after its publication, the genome data have proven to be an essential tool for the study of T. cruzi and increasing efforts to translate this knowledge into the development of new modes of intervention to control Chagas disease are underway.
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Affiliation(s)
- Santuza M Teixeira
- Departamento de Bioquímica e Imunologia, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
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28
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Araújo PR, Teixeira SM. Regulatory elements involved in the post-transcriptional control of stage-specific gene expression in Trypanosoma cruzi: a review. Mem Inst Oswaldo Cruz 2011; 106:257-66. [PMID: 21655811 DOI: 10.1590/s0074-02762011000300002] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2011] [Accepted: 04/07/2011] [Indexed: 11/22/2022] Open
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29
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Abstract
Trypanosomes are a group of protozoan eukaryotes, many of which are major parasites of humans and livestock. The genomes of trypanosomes and their modes of gene expression differ in several important aspects from those of other eukaryotic model organisms. Protein-coding genes are organized in large directional gene clusters on a genome-wide scale, and their polycistronic transcription is not generally regulated at initiation. Transcripts from these polycistrons are processed by global trans-splicing of pre-mRNA. Furthermore, in African trypanosomes, some protein-coding genes are transcribed by a multifunctional RNA polymerase I from a specialized extranucleolar compartment. The primary DNA sequence of the trypanosome genomes and their cellular organization have usually been treated as separate entities. However, it is becoming increasingly clear that in order to understand how a genome functions in a living cell, we will need to unravel how the one-dimensional genomic sequence and its trans-acting factors are arranged in the three-dimensional space of the eukaryotic nucleus. Understanding this cell biology of the genome will be crucial if we are to elucidate the genetic control mechanisms of parasitism. Here, we integrate the concepts of nuclear architecture, deduced largely from studies of yeast and mammalian nuclei, with recent developments in our knowledge of the trypanosome genome, gene expression, and nuclear organization. We also compare this nuclear organization to those in other systems in order to shed light on the evolution of nuclear architecture in eukaryotes.
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Development of a dual reporter system to identify regulatory cis-acting elements in untranslated regions of Trypanosoma cruzi mRNAs. Parasitol Int 2011; 60:161-9. [PMID: 21277385 DOI: 10.1016/j.parint.2011.01.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2010] [Revised: 01/19/2011] [Accepted: 01/20/2011] [Indexed: 01/26/2023]
Abstract
In trypanosomatids, transcription is polycistronic and gene expression control occurs mainly at the post-transcriptional level. To investigate the role of sequences present in the 3'UTR of stage-specific mRNAs of Trypanosoma cruzi, we generated a new vector, named pTcDUALuc, containing the firefly and Renilla luciferase reporter genes. To test this vector, sequences derived from the 3'UTR plus intergenic regions of the alpha tubulin gene, which is up-regulated in epimastigotes, and amastin, which is up-regulated in amastigotes, were inserted downstream from the firefly reporter gene and luciferase activity was compared in transient and stable transfected parasites. As expected, increased luciferase activity was detected in epimastigotes transiently transfected with pTcDUALuc containing tubulin sequences. Using stable transfected cell lines that were allowed to differentiate into amastigotes, we observed increased luciferase activity and mRNA levels in amastigotes transfected with pTcDUALuc containing amastin sequences. We also showed that the spliced leader sequence and poly-A tail were inserted in the predicted sites of the firefly luciferase mRNA and that deletions in the alpha tubulin 3'UTR resulted in decreased luciferase expression because it affects polyadenylation. In contrast to the constructs containing 3'UTR sequences derived from tubulin and amastin genes, the presence of the 3'UTR from a trans-sialidase gene, whose expression is higher in trypomastigotes, resulted in increased luciferase activity in trypomastigotes without a corresponding increase in luciferase mRNA levels.
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31
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Goldenberg S, Ávila AR. Aspects of Trypanosoma cruzi stage differentiation. ADVANCES IN PARASITOLOGY 2011; 75:285-305. [PMID: 21820561 DOI: 10.1016/b978-0-12-385863-4.00013-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Trypanosoma cruzi alternates between different morphological and functional types during its life cycle. Since the discovery of this parasite at the beginning of the twentieth century, efforts have been made to determine the basis of its pathogenesis in the course of Chagas disease and its biochemical constituents. There has also been work to develop tools and strategies for prophylaxis of the important disease caused by these parasites which affects millions of people in Latin America. The identification of axenic conditions allowing T. cruzi growth and differentiation has led to the identification and characterization of stage-specific antigens as well as a better characterization of the biological properties and biochemical particularities of each individual developmental stage. The recent availability of genomic data should pave the way to new progress in our knowledge of the biology and pathogenesis of T. cruzi. This review addresses the differentiation and major stage-specific antigens of T. cruzi and attempts to describe the complexity of the parasite and of the disease it causes.
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32
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Kramer S, Carrington M. Trans-acting proteins regulating mRNA maturation, stability and translation in trypanosomatids. Trends Parasitol 2010; 27:23-30. [PMID: 20609625 PMCID: PMC3070815 DOI: 10.1016/j.pt.2010.06.011] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Revised: 06/05/2010] [Accepted: 06/07/2010] [Indexed: 12/30/2022]
Abstract
In trypanosomatids, alterations in gene expression in response to intrinsic or extrinsic signals are achieved through post-transcriptional mechanisms. In the last 20 years, research has concentrated on defining the responsible cis-elements in the untranslated regions of several regulated mRNAs. More recently, the focus has shifted towards the identification of RNA-binding proteins that act as trans-acting factors. Trypanosomatids have a large number of predicted RNA-binding proteins of which the vast majority have no orthologues in other eukaryotes. Several RNA-binding proteins have been shown to bind and/or regulate the expression of a group of mRNAs that code for functionally related proteins, indicating the possible presence of co-regulated mRNA cohorts.
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Affiliation(s)
- Susanne Kramer
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, UK, CB2 1QW
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33
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Müller M, Padmanabhan PK, Papadopoulou B. Selective inactivation of SIDER2 retroposon-mediated mRNA decay contributes to stage- and species-specific gene expression in Leishmania. Mol Microbiol 2010; 77:471-91. [PMID: 20497500 DOI: 10.1111/j.1365-2958.2010.07226.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Despite their high genomic synteny, the Leishmania major and Leishmania infantum species exhibit extensive differences in mRNA expression patterns throughout the parasite's development. Yet, the underlying mechanisms for this species-specific differential gene expression are largely unknown. Here we report that Short Interspersed DEgenerated Retroposons of the SIDER2 subfamily, shown previously to promote rapid mRNA turnover, confer differential regulation of orthologous transcripts resulting in a stage- and species-specific gene expression. We demonstrate that SIDER2-mediated decay of two L. major transcripts encoding a hypothetical protein and an aminomethyltransferase to a similar extent in promastigote and amastigote developmental forms results in a constitutive low expression of the corresponding proteins. In contrast, their L. infantum orthologs are differentially expressed due to the selective inactivation of SIDER2 in intracellular amastigotes. Inactivation of the SIDER2 function blocks the SIDER2-mediated deadenylation-independent decay pathway, and stabilized transcripts are degraded by a slower, deadenylation-dependent mechanism. Sequence variations in SIDER2 retroposons between orthologous transcripts do not contribute to SIDER2 inactivation. Our data suggest that SIDER2 inactivation is 3'-untranslated region context-dependent and that involves possibly species- and stage-specific trans-acting factor(s). These findings further emphasize the important contribution of SIDER retroposons in the control of gene expression across the Leishmania genus.
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Affiliation(s)
- Michaela Müller
- Infectious Disease Research Center, CHUL Research Center and Department of Microbiology and Immunology, Faculty of Medicine, Laval University, Quebec, Canada
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34
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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.
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Affiliation(s)
- Sandra M Fernández-Moya
- Instituto de Parasitologia y Biomedicina Lopez-Neyra, CSIC, Avenida del Conocimiento, s/n, 18100 Armilla, Granada, Spain
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35
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Cassola A, Frasch AC. An RNA recognition motif mediates the nucleocytoplasmic transport of a trypanosome RNA-binding protein. J Biol Chem 2009; 284:35015-28. [PMID: 19801539 DOI: 10.1074/jbc.m109.031633] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
RNA-binding proteins (RBPs) and RNA metabolism are considered to be important for modulating gene expression in trypanosomes, because these protozoan parasites mainly rely on post-transcriptional mechanisms to regulate protein levels. Previously, we have identified TcUBP1, a single RNA recognition motif (RRM)-type RBP from Trypanosoma cruzi. TcUBP1 is a cytoplasmic protein with roles in stabilization/degradation of mRNAs and in the protection of transcripts through their recruitment into cytoplasmic granules. We now show that TcUBP1, and the closely related protein TcUBP2, can be found in small amounts in the nucleus under normal conditions, and are able to accumulate in the nucleus under arsenite stress. The kinetics of nuclear accumulation, and export to the cytoplasm, are consistent with the shuttling of TcUBP1 between the nucleus and the cytoplasm. The sequence required for TcUBP1 nuclear accumulation was narrowed to the RRM, and point mutations affecting RNA binding abolished nuclear import. This RRM was also shown to be efficiently exported from the nucleus in unstressed parasites, a property that relied on the binding to RNA. TcUBP1 nuclear accumulation was dependent on active transcription, and colocalized with transcripts in the nucleus, suggesting nuclear binding of the mRNA. We propose that TcUBP1 could be linking the mRNA metabolism at both sides of the nuclear pore complex, using the RRM as a nuclear localization signal, and being exported as a cargo on mRNA.
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Affiliation(s)
- Alejandro Cassola
- Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico Chascomús, UNSAM-CONICET, (1650) San Martín, Provincia de Buenos Aires, Argentina
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36
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Minning TA, Weatherly DB, Atwood J, Orlando R, Tarleton RL. The steady-state transcriptome of the four major life-cycle stages of Trypanosoma cruzi. BMC Genomics 2009; 10:370. [PMID: 19664227 PMCID: PMC2907688 DOI: 10.1186/1471-2164-10-370] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2009] [Accepted: 08/07/2009] [Indexed: 12/20/2022] Open
Abstract
Background Chronic chagasic cardiomyopathy is a debilitating and frequently fatal outcome of human infection with the protozoan parasite, Trypanosoma cruzi. Microarray analysis of gene expression during the T. cruzi life-cycle could be a valuable means of identifying drug and vaccine targets based on their appropriate expression patterns, but results from previous microarray studies in T. cruzi and related kinetoplastid parasites have suggested that the transcript abundances of most genes in these organisms do not vary significantly between life-cycle stages. Results In this study, we used whole genome, oligonucleotide microarrays to globally determine the extent to which T. cruzi regulates mRNA relative abundances over the course of its complete life-cycle. In contrast to previous microarray studies in kinetoplastids, we observed that relative transcript abundances for over 50% of the genes detected on the T. cruzi microarrays were significantly regulated during the T. cruzi life-cycle. The significant regulation of 25 of these genes was confirmed by quantitative reverse-transcriptase PCR (qRT-PCR). The T. cruzi transcriptome also mirrored published protein expression data for several functional groups. Among the differentially regulated genes were members of paralog clusters, nearly 10% of which showed divergent expression patterns between cluster members. Conclusion Taken together, these data support the conclusion that transcript abundance is an important level of gene expression regulation in T. cruzi. Thus, microarray analysis is a valuable screening tool for identifying stage-regulated T. cruzi genes and metabolic pathways.
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Affiliation(s)
- Todd A Minning
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia 30602, USA.
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37
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Brandão A. Trypanosomatid EST: a neglected information resource regarding flagellated protozoa? Mem Inst Oswaldo Cruz 2009; 103:622-6. [PMID: 18949338 DOI: 10.1590/s0074-02762008000600021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Adeilton Brandão
- Laboratório de Epidemiologia Molecular de Doenças Infecciosas, Instituto Oswaldo Cruz-Fiocruz, Rio de Janeiro, RJ, Brasil.
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38
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Gentil LG, Cordero EM, do Carmo MS, dos Santos MRM, da Silveira JF. Posttranscriptional mechanisms involved in the control of expression of the stage-specific GP82 surface glycoprotein in Trypanosoma cruzi. Acta Trop 2009; 109:152-8. [PMID: 19013421 DOI: 10.1016/j.actatropica.2008.10.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2008] [Revised: 09/29/2008] [Accepted: 10/14/2008] [Indexed: 01/08/2023]
Abstract
Trypanosoma cruzi metacyclic trypomastigotes express the developmentally regulated GP82 glycoprotein, which is implicated in host cell invasion. Although GP82 mRNA and protein are not present and the mRNAs barely detectable in epimastigotes, nuclear run-on analysis showed that it is transcribed in both stages. This result indicates that accumulation of transcripts in metacyclic forms is not due to increased transcription of the GP82 gene. To investigate whether mRNA stability may be responsible for the differences in the steady-state levels of this mRNA, parasites were treated with actinomycin D or cycloheximide. When treated with actinomycin D, the half-lives estimated for GP82 transcripts were about 6h in metacyclic trypomastigotes and 0.5h in epimastigotes. In the presence of cycloheximide, the levels of GP82 mRNA decayed slightly after 8h in metacyclic trypomastigotes, whereas in epimastigotes the levels of this mRNA increased. This effect suggests a stabilizing mechanism acting in metacyclic trypomastigotes and a destabilizing mechanism in epimastigotes which could be mediated by an element present in the 3'-UTR of the transcripts. Consistent with this finding, northern blot analysis showed that GP82 mRNAs were mobilized to polysomes and consequently translated, but only in metacyclic trypomastigotes.
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Affiliation(s)
- Luciana Girotto Gentil
- Department of Microbiology, Immunology and Parasitology, Escola Paulista de Medicina, UNIFESP, Rua Botucatu, São Paulo, Brazil
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39
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Helm JR, Wilson ME, Donelson JE. Differential expression of a protease gene family in African trypanosomes. Mol Biochem Parasitol 2008; 163:8-18. [PMID: 18848586 DOI: 10.1016/j.molbiopara.2008.09.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2008] [Revised: 09/04/2008] [Accepted: 09/12/2008] [Indexed: 12/01/2022]
Abstract
During their life cycle African trypanosomes must quickly adapt to the different environments of the tsetse fly midgut and the mammalian bloodstream by modulating expression of many of their genes. One group of these differentially expressed genes encodes different forms of a major surface protease. Using a luciferase reporter gene transiently or permanently transfected into trypanosomes, we show here that the 3'-UTRs of these protease genes are responsible for their differential expression. Deletion analysis of the 389-bp 3'-UTR of one of the protease genes, MSP-B, demonstrated that it contains a U-rich regulatory region of about 23bp (UCGUCUGUUAUUUCUUAGUCCAG), which suppresses expression of the reporter protein in bloodstream trypanosomes by as much as 25-fold, but has little effect on the reporter expression in procyclic (tsetse fly) trypanosomes. Replacing the entire 3'-UTR with just this 23-bp element mimicked most of the suppression effect of the complete 3'-UTR. Northern blots showed that the 23-bp element influences the steady state RNA level, but not enough to account for the 25-fold suppression effect. Polysome analyses showed that in procyclic trypanosomes more of the total protease mRNA is associated with intermediate-sized and large polysomes than in bloodstream trypanosomes. Thus, the 23-bp element of this protease gene affects both the level of RNA and its translation.
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Affiliation(s)
- Jared R Helm
- Department of Biochemistry, University of Iowa, 4-339 Bowen Science Bldg., Iowa City, IA 52242, USA
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40
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Rochette A, Raymond F, Ubeda JM, Smith M, Messier N, Boisvert S, Rigault P, Corbeil J, Ouellette M, Papadopoulou B. Genome-wide gene expression profiling analysis of Leishmania major and Leishmania infantum developmental stages reveals substantial differences between the two species. BMC Genomics 2008; 9:255. [PMID: 18510761 PMCID: PMC2453527 DOI: 10.1186/1471-2164-9-255] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2008] [Accepted: 05/29/2008] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Leishmania parasites cause a diverse spectrum of diseases in humans ranging from spontaneously healing skin lesions (e.g., L. major) to life-threatening visceral diseases (e.g., L. infantum). The high conservation in gene content and genome organization between Leishmania major and Leishmania infantum contrasts their distinct pathophysiologies, suggesting that highly regulated hierarchical and temporal changes in gene expression may be involved. RESULTS We used a multispecies DNA oligonucleotide microarray to compare whole-genome expression patterns of promastigote (sandfly vector) and amastigote (mammalian macrophages) developmental stages between L. major and L. infantum. Seven per cent of the total L. infantum genome and 9.3% of the L. major genome were differentially expressed at the RNA level throughout development. The main variations were found in genes involved in metabolism, cellular organization and biogenesis, transport and genes encoding unknown function. Remarkably, this comparative global interspecies analysis demonstrated that only 10-12% of the differentially expressed genes were common to L. major and L. infantum. Differentially expressed genes are randomly distributed across chromosomes further supporting a posttranscriptional control, which is likely to involve a variety of 3'UTR elements. CONCLUSION This study highlighted substantial differences in gene expression patterns between L. major and L. infantum. These important species-specific differences in stage-regulated gene expression may contribute to the disease tropism that distinguishes L. major from L. infantum.
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Affiliation(s)
- Annie Rochette
- Research Centre in Infectious Diseases, CHUL Research Centre and Department of Medical Biology, Faculty of Medicine, Laval University, Quebec, Canada.
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Haile S, Dupé A, Papadopoulou B. Deadenylation-independent stage-specific mRNA degradation in Leishmania. Nucleic Acids Res 2008; 36:1634-44. [PMID: 18250085 PMCID: PMC2275140 DOI: 10.1093/nar/gkn019] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The life cycle of Leishmania alternates between developmental forms residing within the insect vector (e.g. promastigotes) and the mammalian host (amastigotes). In Leishmania nearly all control of gene expression is post-transcriptional and involves sequences in the 3′-untranslated regions (3′UTRs) of mRNAs. Very little is known as to how these cis-elements regulate RNA turnover and translation rates in trypanosomatids and nothing is known about mRNA degradation mechanisms in Leishmania in particular. Here, we use the amastin mRNA—an amastigote-specific transcript—as a model and show that a ∼100 nt U-rich element (URE) within its 3′UTR significantly accounts for developmental regulation. RNase-H-RNA blot analysis revealed that a major part of the rapid promastigote-specific degradation of the amastin mRNA is not initiated by deadenylation. This is in contrast to the amastin mRNA in amastigotes and to reporter RNAs lacking the URE, which, in common with most eukaryotic mRNAs studied to-date, are deadenylated before being degraded. Moreover, our analysis did not reveal a role for decapping in the stage-specific degradation of the amastin mRNA. Overall, these results suggest that degradation of the amastin mRNA of Leishmania is likely to be bi-phasic, the first phase being stage-specific and dependent on an unusual URE-mediated pathway of mRNA degradation.
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Affiliation(s)
- Simon Haile
- Research Centre in Infectious Diseases, CHUL Research Centre and Department of Medical Biology, Faculty of Medicine, Laval University, Quebec, Canada
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Hellman K, Prohaska K, Williams N. Trypanosoma brucei RNA binding proteins p34 and p37 mediate NOPP44/46 cellular localization via the exportin 1 nuclear export pathway. EUKARYOTIC CELL 2007; 6:2206-13. [PMID: 17921352 PMCID: PMC2168238 DOI: 10.1128/ec.00176-07] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2007] [Accepted: 09/21/2007] [Indexed: 11/20/2022]
Abstract
We have previously identified and characterized two novel nuclear RNA binding proteins, p34 and p37, which have been shown to interact with a family of nucleolar phosphoproteins, NOPP44/46, in Trypanosoma brucei. These proteins are nearly identical, the major difference being an 18-amino-acid insert in the N terminus of p37. In order to characterize the interaction between p34 and p37 and NOPP44/46, we have utilized an RNA interference (RNAi) cell line that specifically targets p34 and p37. Within these RNAi cells, we detected a disruption of a higher-molecular-weight complex containing NOPP44/46, as well as a dramatic increase in nuclear NOPP44/46 protein levels. We demonstrated that no change occurred in NOPP44/46 mRNA steady-state levels or stability, nor was there a change in cellular protein levels. These results led us to investigate whether p34 and p37 regulate NOPP44/46 cellular localization. Examination of the p34 and p37 amino acid sequences revealed a leucine-rich nuclear export signal, which interacts with the nuclear export factor exportin 1. Immune capture experiments demonstrated that p34, p37, and NOPP44/46 associate with exportin 1. When these experiments were performed with p34/p37 RNAi cells, NOPP44/46 no longer associated with exportin 1. Sequential immune capture experiments demonstrated that p34, p37, NOPP44/46, and exportin 1 exist in a common complex. Inhibiting exportin 1-mediated nuclear export led to an increase in nuclear NOPP44/46 proteins, indicating that they are exported from the nucleus via this pathway. Together, our results demonstrate that p34 and p37 regulate NOPP44/46 cellular localization by facilitating their association with exportin 1.
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Affiliation(s)
- Kristina Hellman
- Department of Microbiology and Immunology and The Witebsky Center for Microbial Pathogenesis and Immunology, 253 Biomedical Research Building, University at Buffalo, Buffalo, New York 14214, USA
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Hartmann C, Benz C, Brems S, Ellis L, Luu VD, Stewart M, D'Orso I, Busold C, Fellenberg K, Frasch ACC, Carrington M, Hoheisel J, Clayton CE. Small trypanosome RNA-binding proteins TbUBP1 and TbUBP2 influence expression of F-box protein mRNAs in bloodstream trypanosomes. EUKARYOTIC CELL 2007; 6:1964-78. [PMID: 17873084 PMCID: PMC2168414 DOI: 10.1128/ec.00279-07] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In the African trypanosome Trypanosoma brucei nearly all control of gene expression is posttranscriptional; sequences in the 3'-untranslated regions of mRNAs determine the steady-state mRNA levels by regulation of RNA turnover. Here we investigate the roles of two related proteins, TbUBP1 and TbUBP2, containing a single RNA recognition motif, in trypanosome gene expression. TbUBP1 and TbUBP2 are in the cytoplasm and nucleus, comprise ca. 0.1% of the total protein, and are not associated with polysomes or RNA degradation enzymes. Overexpression of TbUBP2 upregulated the levels of several mRNAs potentially involved in cell division, including the CFB1 mRNA, which encodes a protein with a cyclin F-box domain. CFB1 regulation was mediated by the 3'-untranslated region and involved stabilization of the mRNA. Depletion of TbUBP2 and TbUBP1 inhibited growth and downregulated expression of the cyclin F box protein gene CFB2; trans splicing was unaffected. The results of pull-down assays indicated that all tested mRNAs were bound to TbUBP2 or TbUBP1, with some preference for CFB1. We suggest that TbUBP1 and TbUBP2 may be relatively nonspecific RNA-binding proteins and that specific effects of overexpression or depletion could depend on competition between various different proteins for RNA binding.
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Affiliation(s)
- Claudia Hartmann
- Zentrum für Molekulare Biologie der Universität Heidelberg, Im Neuenheimer Feld 282, D-69120 Heidelberg, Germany
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44
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Cassola A, De Gaudenzi JG, Frasch AC. Recruitment of mRNAs to cytoplasmic ribonucleoprotein granules in trypanosomes. Mol Microbiol 2007; 65:655-70. [PMID: 17635187 DOI: 10.1111/j.1365-2958.2007.05833.x] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Trypanosomes are outstanding examples of the importance of mRNA metabolism in the regulation of gene expression, as these unicellular eukaryotes mostly control protein synthesis by post-transcriptional mechanisms. Here, we show that mRNA metabolism in these organisms involves recruitment of mRNAs and proteins to microscopically visible ribonucleoprotein granules in the cytoplasm. These structures engage transcripts that are being translated and protect mRNAs from degradation. Analysis of the protein composition of trypanosomal mRNA granules indicated that they contain orthologous proteins to those present in P bodies and stress granules from metazoan organisms. Formation of mRNA granules was observed after carbon-source deprivation of parasites in axenic culture. More important, mRNA granules are formed naturally in trypanosomes present in the intestinal tract of the insect vector. We suggest that trypanosomes make use of mRNA granules for transient transcript protection as a strategy to cope with periods of starvation that they have to face during their complex life cycles.
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Affiliation(s)
- Alejandro Cassola
- Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico Chascomús, UNSAM-CONICET, 1650 San Martín, Provincia de Buenos Aires, Argentina
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Pérez-Díaz L, Duhagon MA, Smircich P, Sotelo-Silveira J, Robello C, Krieger MA, Goldenberg S, Williams N, Dallagiovanna B, Garat B. Trypanosoma cruzi: molecular characterization of an RNA binding protein differentially expressed in the parasite life cycle. Exp Parasitol 2007; 117:99-105. [PMID: 17475252 PMCID: PMC2020836 DOI: 10.1016/j.exppara.2007.03.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2006] [Revised: 03/02/2007] [Accepted: 03/14/2007] [Indexed: 12/18/2022]
Abstract
Molecular studies have shown several peculiarities in the regulatory mechanisms of gene expression in trypanosomatids. Protein coding genes are organized in long polycistronic units that seem to be constitutively transcribed. Therefore, post-transcriptional regulation of gene expression is considered to be the main point for control of transcript abundance and functionality. Here we describe the characterization of a 17 kDa RNA-binding protein from Trypanosoma cruzi (TcRBP19) containing an RNA recognition motive (RRM). This protein is coded by a single copy gene located in a high molecular weight chromosome of T. cruzi. Orthologous genes are present in the TriTryp genomes. TcRBP19 shows target selectivity since among the different homoribopolymers it preferentially binds polyC. TcRBP19 is a low expression protein only barely detected at the amastigote stage localizing in a diffuse pattern in the cytoplasm.
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Affiliation(s)
- Leticia Pérez-Díaz
- Laboratorio de Interacciones Moleculares, Facultad de Ciencias, Iguá 4225, 11400 Montevideo, Uruguay
| | - María Ana Duhagon
- Laboratorio de Interacciones Moleculares, Facultad de Ciencias, Iguá 4225, 11400 Montevideo, Uruguay
| | - Pablo Smircich
- Laboratorio de Interacciones Moleculares, Facultad de Ciencias, Iguá 4225, 11400 Montevideo, Uruguay
| | - José Sotelo-Silveira
- Departamento de Biología Celular y Molecular, Facultad de Ciencias, Iguá 4225, 11400 Montevideo, Uruguay
- Departamento de Neurobiología Celular y Molecular, Instituto de Investigaciones Biológicas Clemente Estable Avda Italia 3318, Montevideo, Uruguay
| | - Carlos Robello
- Departamento de Bioquímica, Facultad de Medicina, Gral Flores 2125, 11800, Montevideo, Uruguay
| | - Marco Aurelio Krieger
- Instituto de Biología Molecular do Paraná, Rua Profesor Algacyr Munhoz Mader 3775, Curitiba 81350-010, Brazil
| | - Samuel Goldenberg
- Instituto de Biología Molecular do Paraná, Rua Profesor Algacyr Munhoz Mader 3775, Curitiba 81350-010, Brazil
| | - Noreen Williams
- Dept. of Microbiology and Immunology. 253 Biomedical Research Building. University at Buffalo. Buffalo 14214, NY. USA
| | - Bruno Dallagiovanna
- Instituto de Biología Molecular do Paraná, Rua Profesor Algacyr Munhoz Mader 3775, Curitiba 81350-010, Brazil
- Corresponding authors: fax: +598 2 525 86 17 E-mail: (B. Garat); or fax: +55 41 33163267 E-mail: (B. Dallagiovanna)
| | - Beatriz Garat
- Laboratorio de Interacciones Moleculares, Facultad de Ciencias, Iguá 4225, 11400 Montevideo, Uruguay
- Corresponding authors: fax: +598 2 525 86 17 E-mail: (B. Garat); or fax: +55 41 33163267 E-mail: (B. Dallagiovanna)
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Jäger AV, De Gaudenzi JG, Cassola A, D'Orso I, Frasch AC. mRNA maturation by two-step trans-splicing/polyadenylation processing in trypanosomes. Proc Natl Acad Sci U S A 2007; 104:2035-42. [PMID: 17267594 PMCID: PMC1892994 DOI: 10.1073/pnas.0611125104] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2006] [Indexed: 11/18/2022] Open
Abstract
Trypanosomes are unique eukaryotic cells, in that they virtually lack mechanisms to control gene expression at the transcriptional level. These microorganisms mostly control protein synthesis by posttranscriptional regulation processes, like mRNA stabilization and degradation. Transcription in these cells is polycistronic. Tens to hundreds of protein-coding genes of unrelated function are arrayed in long clusters on the same DNA strand. Polycistrons are cotranscriptionally processed by trans-splicing at the 5' end and polyadenylation at the 3' end, generating monocistronic units ready for degradation or translation. In this work, we show that some trans-splicing/polyadenylation sites may be skipped during normal polycistronic processing. As a consequence, dicistronic units or monocistronic transcripts having long 3' UTRs are produced. Interestingly, these unspliced transcripts can be processed into mature mRNAs by the conventional trans-splicing/polyadenylation events leading to translation. To our knowledge, this is a previously undescribed mRNA maturation by trans-splicing uncoupled from transcription. We identified an RNA-recognition motif-type protein, homologous to the mammalian polypyrimidine tract-binding protein, interacting with one of the partially processed RNAs analyzed here that might be involved in exon skipping. We propose that splice-site skipping might be part of a posttranscriptional mechanism to regulate gene expression in trypanosomes, through the generation of premature nontranslatable RNA molecules.
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Affiliation(s)
- Adriana V. Jäger
- Instituto de Investigaciones Biotecnológicas–Instituto Tecnológico Chascomus, Universidad Nacional de San Martín–Consejo Nacional de Investigaciones Científicas y Técnicas, Avenida Gral. Paz 5445, Edificio 24, INTI, 1650 San Martín, Provincia de Buenos Aires, Argentina
| | - Javier G. De Gaudenzi
- Instituto de Investigaciones Biotecnológicas–Instituto Tecnológico Chascomus, Universidad Nacional de San Martín–Consejo Nacional de Investigaciones Científicas y Técnicas, Avenida Gral. Paz 5445, Edificio 24, INTI, 1650 San Martín, Provincia de Buenos Aires, Argentina
| | - Alejandro Cassola
- Instituto de Investigaciones Biotecnológicas–Instituto Tecnológico Chascomus, Universidad Nacional de San Martín–Consejo Nacional de Investigaciones Científicas y Técnicas, Avenida Gral. Paz 5445, Edificio 24, INTI, 1650 San Martín, Provincia de Buenos Aires, Argentina
| | - Iván D'Orso
- Instituto de Investigaciones Biotecnológicas–Instituto Tecnológico Chascomus, Universidad Nacional de San Martín–Consejo Nacional de Investigaciones Científicas y Técnicas, Avenida Gral. Paz 5445, Edificio 24, INTI, 1650 San Martín, Provincia de Buenos Aires, Argentina
| | - Alberto C. Frasch
- Instituto de Investigaciones Biotecnológicas–Instituto Tecnológico Chascomus, Universidad Nacional de San Martín–Consejo Nacional de Investigaciones Científicas y Técnicas, Avenida Gral. Paz 5445, Edificio 24, INTI, 1650 San Martín, Provincia de Buenos Aires, Argentina
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Buscaglia CA, Campo VA, Frasch ACC, Di Noia JM. Trypanosoma cruzi surface mucins: host-dependent coat diversity. Nat Rev Microbiol 2006; 4:229-36. [PMID: 16489349 DOI: 10.1038/nrmicro1351] [Citation(s) in RCA: 209] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The surface of the protozoan parasite Trypanosoma cruzi is covered in mucins, which contribute to parasite protection and to the establishment of a persistent infection. Their importance is highlighted by the fact that the approximately 850 mucin-encoding genes comprise approximately 1% of the parasite genome and approximately 6% of all predicted T. cruzi genes. The coordinate expression of a large repertoire of mucins containing variable regions in the mammal-dwelling stages of the T. cruzi life cycle suggests a possible strategy to thwart the host immune response. Here, we discuss the expression profiling of T. cruzi mucins, the mechanisms leading to the acquisition of mucin diversity and the possible consequences of a mosaic surface coat in the interplay between parasite and host.
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Affiliation(s)
- Carlos A Buscaglia
- Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús (IIB-INTECH), Universidad Nacional de General San Martn-CONICET, San Martín (1650), Buenos Aires, Argentina
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48
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De Gaudenzi J, Frasch AC, Clayton C. RNA-binding domain proteins in Kinetoplastids: a comparative analysis. EUKARYOTIC CELL 2006; 4:2106-14. [PMID: 16339728 PMCID: PMC1317496 DOI: 10.1128/ec.4.12.2106-2114.2005] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
RNA-binding proteins are important in many aspects of RNA processing, function, and destruction. One class of such proteins contains the RNA recognition motif (RRM), which consists of about 90 amino acid residues, including the canonical RNP1 octapeptide: (K/R)G(F/Y)(G/A)FVX(F/Y). We used a variety of homology searches to classify all of the RRM proteins of the three kinetoplastids Trypanosoma brucei, Trypanosoma cruzi, and Leishmania major. All three organisms have similar sets of RRM-containing protein orthologues, suggesting common posttranscriptional processing and regulatory pathways. Of the 75 RRM proteins identified in T. brucei, only 13 had clear homologues in other eukaryotes, although 8 more could be given putative functional assignments. A comparison with the 18 RRM proteins of the obligate intracellular parasite Encephalitozoon cuniculi revealed just 3 RRM proteins which appear to be conserved at the primary sequence level throughout eukaryotic evolution: poly(A) binding protein, the rRNA-processing protein MRD1, and the nuclear cap binding protein.
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Affiliation(s)
- Javier De Gaudenzi
- Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús, CONICET-UNSAM, Av. Gral Paz 5445, 1650 Buenos Aires, Argentina
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49
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Purdy JE, Donelson JE, Wilson ME. Regulation of genes encoding the major surface protease of Leishmania chagasi via mRNA stability. Mol Biochem Parasitol 2005; 142:88-97. [PMID: 15876463 DOI: 10.1016/j.molbiopara.2005.03.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2004] [Revised: 03/16/2005] [Accepted: 03/23/2005] [Indexed: 01/08/2023]
Abstract
The intercoding regions between many Leishmania sp. genes regulate their mRNA expression. The MSPL mRNA, encoding a subclass of the major surface protease (MSP) of Leishmania chagasi, increases in abundance, when protein synthesis is arrested, while alpha-tubulin (alpha-TUB) mRNA and most other mRNAs do not. We found that the intercoding region between MSPL-coding regions, when cloned downstream of the beta-galactosidase reporter gene (beta-GAL), caused beta-GAL mRNA to increase 8- to 10-fold after inhibiting protein synthesis with cycloheximide. Stable L. chagasi transfectants containing hybrid MSPL/alpha-TUB intercoding regions cloned downstream of beta-GAL were made. The alpha-TUB intercoding region induced high-level baseline beta-GAL mRNA that increased only 1.3-fold after incubation with cycloheximide. In contrast, the MSPL intercoding region, as well as constructs containing nucleotides 303-505 from the MSPL 3'UTR, caused steady-state beta-GAL mRNA levels in the absence of cycloheximide that were approximately 10% of alpha-TUB constructs. These levels increased between 4.4- and 13.2-fold after cycloheximide was added. Constructs containing half of this region (303-394 or 395-505) produced intermediate levels of beta-GAL mRNA and intermediate levels of cycloheximide induction. The kinetics of cycloheximide induction of beta-GAL mRNA was similar with region 303-505 constructs as with constructs bearing the entire endogenous MSPL intercoding region. Furthermore, region 303-505 increased reporter mRNA abundance after cycloheximide by increasing mRNA half-life. Hence, we have identified a 202-nucleotide region within the MSPL 3'UTR that is in part responsible for cycloheximide induction. We hypothesize that this region may interact with labile regulatory protein factor(s).
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Affiliation(s)
- Jay E Purdy
- Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, USA.
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50
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Rochette A, McNicoll F, Girard J, Breton M, Leblanc E, Bergeron MG, Papadopoulou B. Characterization and developmental gene regulation of a large gene family encoding amastin surface proteins in Leishmania spp. Mol Biochem Parasitol 2005; 140:205-20. [PMID: 15760660 DOI: 10.1016/j.molbiopara.2005.01.006] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2004] [Accepted: 01/14/2005] [Indexed: 11/23/2022]
Abstract
The ability of Leishmania amastigotes to survive within the drastic environmental changes encountered in the phagolysosomes of mammalian macrophages is heavily dependent on the developmental regulation of a variety of genes. The identification of genes that are expressed preferentially in the mammalian stage of the parasite should increase our understanding of the molecular mechanisms regulating stage-specific gene expression and of the determinants that control its intracellular survival and contribute to its pathogenesis. We report here detailed sequence characterization and structural organization of the amastin gene family in Leishmania major and Leishmania infantum and the study of their developmental gene regulation throughout the parasite's life cycle. Amastin surface proteins represent the largest developmentally regulated gene family reported so far in Leishmania comprising up to 45 members. All the members of the amastin gene family in both Leishmania and Trypanosoma species share a similar structural organization and contain a highly conserved 11 amino acid extracellular domain, which is unique to amastin proteins. The majority of the amastin gene homologs are specifically expressed in the amastigote stage of the parasite. Three distinct RNA elements were identified in the 3'-untranslated regions (3'UTR) of the amastin transcripts. The majority of these transcripts contain a conserved 450 nt cis-acting 3'UTR element shown previously to regulate stage-specific gene expression at the level of translation, which suggests that several amastin homologs may be regulated by a similar mechanism of translational control inside the macrophage. These findings further highlight the unique features of gene expression control in Leishmania.
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Affiliation(s)
- Annie Rochette
- Infectious Diseases Research Center, RC-709, CHUL Research Center and Department of Medical Biology, Faculty of Medicine, Laval University, 2705 Laurier Blvd., Ste-Foy (QC), Que., Canada G1V 4G2
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