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Silvester E, Szoor B, Ivens A, Awuah-Mensah G, Gadelha C, Wickstead B, Matthews KR. A conserved trypanosomatid differentiation regulator controls substrate attachment and morphological development in Trypanosoma congolense. PLoS Pathog 2024; 20:e1011889. [PMID: 38408115 PMCID: PMC10919850 DOI: 10.1371/journal.ppat.1011889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Revised: 03/07/2024] [Accepted: 02/08/2024] [Indexed: 02/28/2024] Open
Abstract
Trypanosomatid parasites undergo developmental regulation to adapt to the different environments encountered during their life cycle. In Trypanosoma brucei, a genome wide selectional screen previously identified a regulator of the protein family ESAG9, which is highly expressed in stumpy forms, a morphologically distinct bloodstream stage adapted for tsetse transmission. This regulator, TbREG9.1, has an orthologue in Trypanosoma congolense, despite the absence of a stumpy morphotype in that parasite species, which is an important cause of livestock trypanosomosis. RNAi mediated gene silencing of TcREG9.1 in Trypanosoma congolense caused a loss of attachment of the parasites to a surface substrate in vitro, a key feature of the biology of these parasites that is distinct from T. brucei. This detachment was phenocopied by treatment of the parasites with a phosphodiesterase inhibitor, which also promotes detachment in the insect trypanosomatid Crithidia fasciculata. RNAseq analysis revealed that TcREG9.1 silencing caused the upregulation of mRNAs for several classes of surface molecules, including transferrin receptor-like molecules, immunoreactive proteins in experimental bovine infections, and molecules related to those associated with stumpy development in T. brucei. Depletion of TcREG9.1 in vivo also generated an enhanced level of parasites in the blood circulation consistent with reduced parasite attachment to the microvasculature. The morphological progression to insect forms of the parasite was also perturbed. We propose a model whereby TcREG9.1 acts as a regulator of attachment and development, with detached parasites being adapted for transmission.
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Affiliation(s)
- Eleanor Silvester
- Institute for Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Ashworth laboratories, Charlotte Auerbach Road, Edinburgh, United Kingdom
| | - Balazs Szoor
- Institute for Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Ashworth laboratories, Charlotte Auerbach Road, Edinburgh, United Kingdom
| | - Alasdair Ivens
- Institute for Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Ashworth laboratories, Charlotte Auerbach Road, Edinburgh, United Kingdom
| | - Georgina Awuah-Mensah
- Medical School, Centre for Genetics and Genomics, School of Life Sciences, Queen’s Medical Centre, University of Nottingham, Nottingham, United Kingdom
| | - Catarina Gadelha
- Medical School, Centre for Genetics and Genomics, School of Life Sciences, Queen’s Medical Centre, University of Nottingham, Nottingham, United Kingdom
| | - Bill Wickstead
- Medical School, Centre for Genetics and Genomics, School of Life Sciences, Queen’s Medical Centre, University of Nottingham, Nottingham, United Kingdom
| | - Keith R. Matthews
- Institute for Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Ashworth laboratories, Charlotte Auerbach Road, Edinburgh, United Kingdom
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Morrison LJ, Steketee PC, Tettey MD, Matthews KR. Pathogenicity and virulence of African trypanosomes: From laboratory models to clinically relevant hosts. Virulence 2023; 14:2150445. [PMID: 36419235 DOI: 10.1080/21505594.2022.2150445] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
African trypanosomes are vector-borne protozoa, which cause significant human and animal disease across sub-Saharan Africa, and animal disease across Asia and South America. In humans, infection is caused by variants of Trypanosoma brucei, and is characterized by varying rate of progression to neurological disease, caused by parasites exiting the vasculature and entering the brain. Animal disease is caused by multiple species of trypanosome, primarily T. congolense, T. vivax, and T. brucei. These trypanosomes also infect multiple species of mammalian host, and this complexity of trypanosome and host diversity is reflected in the spectrum of severity of disease in animal trypanosomiasis, ranging from hyperacute infections associated with mortality to long-term chronic infections, and is also a main reason why designing interventions for animal trypanosomiasis is so challenging. In this review, we will provide an overview of the current understanding of trypanosome determinants of infection progression and severity, covering laboratory models of disease, as well as human and livestock disease. We will also highlight gaps in knowledge and capabilities, which represent opportunities to both further our fundamental understanding of how trypanosomes cause disease, as well as facilitating the development of the novel interventions that are so badly needed to reduce the burden of disease caused by these important pathogens.
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Affiliation(s)
- Liam J Morrison
- Roslin Institute, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian, UK
| | - Pieter C Steketee
- Roslin Institute, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian, UK
| | - Mabel D Tettey
- Institute for Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - Keith R Matthews
- Institute for Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
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Briggs EM, Marques CA, Oldrieve GR, Hu J, Otto TD, Matthews KR. Profiling the bloodstream form and procyclic form Trypanosoma brucei cell cycle using single-cell transcriptomics. eLife 2023; 12:e86325. [PMID: 37166108 PMCID: PMC10212563 DOI: 10.7554/elife.86325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 05/10/2023] [Indexed: 05/12/2023] Open
Abstract
African trypanosomes proliferate as bloodstream forms (BSFs) and procyclic forms in the mammal and tsetse fly midgut, respectively. This allows them to colonise the host environment upon infection and ensure life cycle progression. Yet, understanding of the mechanisms that regulate and drive the cell replication cycle of these forms is limited. Using single-cell transcriptomics on unsynchronised cell populations, we have obtained high resolution cell cycle regulated (CCR) transcriptomes of both procyclic and slender BSF Trypanosoma brucei without prior cell sorting or synchronisation. Additionally, we describe an efficient freeze-thawing protocol that allows single-cell transcriptomic analysis of cryopreserved T. brucei. Computational reconstruction of the cell cycle using periodic pseudotime inference allowed the dynamic expression patterns of cycling genes to be profiled for both life cycle forms. Comparative analyses identify a core cycling transcriptome highly conserved between forms, as well as several genes where transcript levels dynamics are form specific. Comparing transcript expression patterns with protein abundance revealed that the majority of genes with periodic cycling transcript and protein levels exhibit a relative delay between peak transcript and protein expression. This work reveals novel detail of the CCR transcriptomes of both forms, which are available for further interrogation via an interactive webtool.
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Affiliation(s)
- Emma M Briggs
- Institute for Immunology and Infection Research, School of Biological Sciences, University of EdinburghEdinburghUnited Kingdom
- Wellcome Centre for Integrative Parasitology, School of Infection & Immunity, University of GlasgowGlasgowUnited Kingdom
| | - Catarina A Marques
- Wellcome Centre for Integrative Parasitology, School of Infection & Immunity, University of GlasgowGlasgowUnited Kingdom
| | - Guy R Oldrieve
- Institute for Immunology and Infection Research, School of Biological Sciences, University of EdinburghEdinburghUnited Kingdom
| | - Jihua Hu
- Institute for Immunology and Infection Research, School of Biological Sciences, University of EdinburghEdinburghUnited Kingdom
| | - Thomas D Otto
- Wellcome Centre for Integrative Parasitology, School of Infection & Immunity, University of GlasgowGlasgowUnited Kingdom
| | - Keith R Matthews
- Institute for Immunology and Infection Research, School of Biological Sciences, University of EdinburghEdinburghUnited Kingdom
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Wen YZ, Tang HT, Cai XL, Wu N, Xu JZ, Su BX, Hide G, Lun ZR, Lai DH. PAG3 promotes the differentiation of bloodstream forms in Trypanosoma brucei and reveals the evolutionary relationship among the Trypanozoon trypanosomes. Front Cell Infect Microbiol 2022. [DOI: 10.3389/fcimb.2022.1021332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
IntroductionTrypanosoma brucei, T. evansi and T. equiperdum are members of the subgenus Trypanozoon and are highly similar morphologically and genetically. The main differences between these three species are their differentiation patterns in the hosts and the role of vectors in their life cycles. However, the mechanisms causing these differences are still controversial.MethodsPAG3 gene was accessed by PCR amplification in 26 strains of Trypanozoon and sequences were then analyzed by BLAST accompanied with T. evansitype B group. RNA interference and CRISPR/Cas9 were used for revealing possible role of PAG3 in slender to stumpy transformation.ResultsThe procyclin associated gene 3 (PAG3) can be found in the pleomorphicspecies, T.brucei, which undergoes differentiation of slender forms to the stumpy form. This differentiation process is crucial for transmission to the tsetse fly vector. However, a homologue of PAG3 was not detected in either T. evansi or in the majority of T. equiperdum strains which are allmonomorphic. Furthere xperiments in T. brucei demonstrated that, when PAG3 was down-regulated or absent, there was a significant reduction in the differentiation from slender to stumpy forms.ConclusionTherefore, we conclude that PAG3 is a key nuclear gene involved in the slender to stumpy differentiation pathway of T.brucei in the mammalian host. Loss of this gene might also offer a simple evolutionary mechanism explaining why T. evansi and some T. equiperdum have lost the ability to differentiate and have been driven to adapt to transmission cycles that by pass the tsetse vector or mechanical contact.
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Falk F, Melo Palhares R, Waithaka A, Clayton C. Roles and interactions of the specialized initiation factors EIF4E2, EIF4E5 and EIF4E6 in Trypanosoma brucei: EIF4E2 maintains the abundances of S-phase mRNAs. Mol Microbiol 2022; 118:457-476. [PMID: 36056730 DOI: 10.1111/mmi.14978] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 08/14/2022] [Accepted: 08/30/2022] [Indexed: 11/29/2022]
Abstract
Trypanosoma brucei has six versions of the cap-binding translation initiation factor EIF4E. We investigated the functions of EIF4E2, EIF4E3, EIF4E5 and EIF4E6 in bloodstream forms. We confirmed the protein associations previously found in procyclic forms, and detected specific co-purification of some RNA-binding proteins. Bloodstream forms lacking EIF4E5 grew normally and differentiated to replication-incompetent procyclic forms. Depletion of EIF4E6 inhibited bloodstream-form trypanosome growth and translation. EIF4E2 co-purified only the putative RNA binding protein SLBP2. Bloodstream forms lacking EIF4E2 multiplied slowly, had a low maximal cell density, and expressed the stumpy-form marker PAD1, but showed no evidence for enhanced stumpy-form signalling. EIF4E2 knock-out cells differentiated readily to replication-competent procyclic forms. EIF4E2 was strongly associated with a subset of mRNAs that are maximally abundant in S-phase, and these all had decreased abundances in EIF4E2 knock-out cells. Three EIF4E2 target mRNAs are also bound and stabilized by the Pumilio domain protein PUF9. Yeast 2-hybrid results suggested that PUF9 interacts directly with SLBP2, but PUF9 was not detected in EIF4E2 pull-downs. We speculate that the EIF4E2-SLBP2 complex might interact with its target mRNAs, perhaps via PUF9, only early during G1/S, stabilizing the mRNAs in preparation for translation later in S-phase or in early G2.
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Affiliation(s)
- Franziska Falk
- Heidelberg University Centre for Molecular Biology (ZMBH), Im Neuenheimer Feld, Heidelberg, Germany
| | - Rafael Melo Palhares
- Heidelberg University Centre for Molecular Biology (ZMBH), Im Neuenheimer Feld, Heidelberg, Germany.,Institut für Mikro- und Molekularbiologie, Justus-Liebig-Universität Giessen, IFZ, Heinrich-Buff-Ring 26-32, 35392 Giessen, Germany
| | - Albina Waithaka
- Heidelberg University Centre for Molecular Biology (ZMBH), Im Neuenheimer Feld, Heidelberg, Germany
| | - Christine Clayton
- Heidelberg University Centre for Molecular Biology (ZMBH), Im Neuenheimer Feld, Heidelberg, Germany
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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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Cooper S, Wadsworth ES, Schnaufer A, Savill NJ. Organization of minicircle cassettes and guide RNA genes in Trypanosoma brucei. RNA (NEW YORK, N.Y.) 2022; 28:972-992. [PMID: 35414587 PMCID: PMC9202587 DOI: 10.1261/rna.079022.121] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 03/27/2022] [Indexed: 06/14/2023]
Abstract
Mitochondrial DNA of protists of order Kinetoplastida comprises thousands of interlinked circular molecules arranged in a network. There are two types of molecules called minicircles and maxicircles. Minicircles encode guide RNA (gRNA) genes whose transcripts mediate post-transcriptional editing of maxicircle encoded genes. Minicircles are diverse. The human sleeping sickness parasite Trypanosoma brucei has one of the most diverse sets of minicircle classes of all studied trypanosomatids with hundreds of different classes, each encoding one to four genes mainly within cassettes framed by 18 bp inverted repeats. A third of cassettes have no identifiable gRNA genes even though their sequence structures are similar to cassettes with identifiable genes. Only recently have almost all minicircle classes for some subspecies and isolates of T. brucei been sequenced and annotated with corresponding verification of gRNA expression by small-RNA transcriptome data. These data sets provide a rich resource for understanding the structure of minicircle classes, cassettes and gRNA genes and their transcription. Here, we provide a statistical description of the functionality, expression status, structure and sequence of gRNA genes in a differentiation-competent, laboratory-adapted strain of T. brucei We obtain a clearer definition of what is a gRNA gene. Our analysis supports the idea that many, if not all, cassettes without an identifiable gRNA gene contain decaying remnants of once functional gRNA genes. Finally, we report several new, unexplained discoveries such as the association between cassette position on the minicircle and gene expression and functionality, and the association between gene initiation sequence and anchor position.
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Affiliation(s)
- Sinclair Cooper
- Institute of Immunology and Infection Research, University of Edinburgh, Edinburgh, Scotland EH9 3FL, United Kingdom
| | - Elizabeth S Wadsworth
- Institute of Immunology and Infection Research, University of Edinburgh, Edinburgh, Scotland EH9 3FL, United Kingdom
| | - Achim Schnaufer
- Institute of Immunology and Infection Research, University of Edinburgh, Edinburgh, Scotland EH9 3FL, United Kingdom
| | - Nicholas J Savill
- Institute of Immunology and Infection Research, University of Edinburgh, Edinburgh, Scotland EH9 3FL, United Kingdom
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Kent RS, Briggs EM, Colon BL, Alvarez C, Silva Pereira S, De Niz M. Paving the Way: Contributions of Big Data to Apicomplexan and Kinetoplastid Research. Front Cell Infect Microbiol 2022; 12:900878. [PMID: 35734575 PMCID: PMC9207352 DOI: 10.3389/fcimb.2022.900878] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 05/06/2022] [Indexed: 11/13/2022] Open
Abstract
In the age of big data an important question is how to ensure we make the most out of the resources we generate. In this review, we discuss the major methods used in Apicomplexan and Kinetoplastid research to produce big datasets and advance our understanding of Plasmodium, Toxoplasma, Cryptosporidium, Trypanosoma and Leishmania biology. We debate the benefits and limitations of the current technologies, and propose future advancements that may be key to improving our use of these techniques. Finally, we consider the difficulties the field faces when trying to make the most of the abundance of data that has already been, and will continue to be, generated.
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Affiliation(s)
- Robyn S. Kent
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, VT, United States
| | - Emma M. Briggs
- Institute for Immunology and Infection Research, School of Biological Sciences, University Edinburgh, Edinburgh, United Kingdom
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Beatrice L. Colon
- Wellcome Centre for Anti-Infectives Research, Division of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Catalina Alvarez
- de Duve Institute, Université Catholique de Louvain, Brussels, Belgium
| | - Sara Silva Pereira
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina da Universidade de Lisboa, Lisboa, Portugal
| | - Mariana De Niz
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina da Universidade de Lisboa, Lisboa, Portugal
- Institut Pasteur, Paris, France
- *Correspondence: Mariana De Niz,
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Silva Pereira S, Mathenge K, Masiga D, Jackson A. Transcriptomic profiling of Trypanosoma congolense mouthpart parasites from naturally infected flies. Parasit Vectors 2022; 15:152. [PMID: 35501882 PMCID: PMC9063227 DOI: 10.1186/s13071-022-05258-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 03/29/2022] [Indexed: 11/10/2022] Open
Abstract
Background Animal African trypanosomiasis, or nagana, is a veterinary disease caused by African trypanosomes transmitted by tsetse flies. In Africa, Trypanosoma congolense is one of the most pathogenic and prevalent causes of nagana in livestock, resulting in high animal morbidity and mortality and extensive production losses. In the tsetse fly, parasites colonise the midgut and eventually reach the mouthparts, from where they can be transmitted as the fly feeds on vertebrate hosts such as cattle. Despite the extreme importance of mouthpart-form parasites for disease transmission, very few global expression profile studies have been conducted in these parasite forms. Methods Here, we collected tsetse flies from the Shimba Hills National Reserve, a wildlife area in southeast Kenya, diagnosed T. congolense infections, and sequenced the transcriptomes of the T. congolense parasites colonising the mouthparts of the flies. Results We found little correlation between mouthpart parasites from natural and experimental fly infections. Furthermore, we performed differential gene expression analysis between mouthpart and bloodstream parasite forms and identified several surface-expressed genes and 152 novel hypothetical proteins differentially expressed in mouthpart parasites. Finally, we profiled variant antigen expression and observed that a variant surface glycoprotein (VSG) transcript belonging to T. congolense phylotype 8 (i.e. TcIL3000.A.H_000381200), previously observed to be enriched in metacyclic transcriptomes, was present in all wild-caught mouthpart samples as well as bloodstream-form parasites, suggestive of constitutive expression. Conclusion Our study provides transcriptomes of trypanosome parasites from naturally infected tsetse flies and suggests that a phylotype 8 VSG gene is constitutively expressed in metacyclic- and bloodstream-form parasites at the population level. Graphical Abstract ![]()
Supplementary Information The online version contains supplementary material available at 10.1186/s13071-022-05258-y.
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Affiliation(s)
- Sara Silva Pereira
- Department of Infection Biology and Microbiomes, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, 146 Brownlow Hill, Liverpool, L3 5RF, UK. .,Faculdade de Medicina, Instituto de Medicina Molecular - João Lobo Antunes, Universidade de Lisboa, Lisbon, Portugal.
| | - Kawira Mathenge
- International Centre of Insect Physiology and Ecology, Nairobi, Kenya
| | - Daniel Masiga
- International Centre of Insect Physiology and Ecology, Nairobi, Kenya
| | - Andrew Jackson
- Department of Infection Biology and Microbiomes, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, 146 Brownlow Hill, Liverpool, L3 5RF, UK.
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Bishola Tshitenge T, Reichert L, Liu B, Clayton C. Several different sequences are implicated in bloodstream-form-specific gene expression in Trypanosoma brucei. PLoS Negl Trop Dis 2022; 16:e0010030. [PMID: 35312693 PMCID: PMC8982893 DOI: 10.1371/journal.pntd.0010030] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 04/05/2022] [Accepted: 03/03/2022] [Indexed: 12/30/2022] Open
Abstract
The parasite Trypanosoma brucei grows as bloodstream forms in mammalian hosts, and as procyclic forms in tsetse flies. In trypanosomes, gene expression regulation depends heavily on post-transcriptional mechanisms. Both the RNA-binding protein RBP10 and glycosomal phosphoglycerate kinase PGKC are expressed only in mammalian-infective forms. RBP10 targets procyclic-specific mRNAs for destruction, while PGKC is required for bloodstream-form glycolysis. Developmental regulation of both is essential: expression of either RBP10 or PGKC in procyclic forms inhibits their proliferation. We show that the 3’-untranslated region of the RBP10 mRNA is extraordinarily long—7.3kb—and were able to identify six different sequences, scattered across the untranslated region, which can independently cause bloodstream-form-specific expression. The 3’-untranslated region of the PGKC mRNA, although much shorter, still contains two different regions, of 125 and 153nt, that independently gave developmental regulation. No short consensus sequences were identified that were enriched either within these regulatory regions, or when compared with other mRNAs with similar regulation, suggesting that more than one regulatory RNA-binding protein is important for repression of mRNAs in procyclic forms. We also identified regions, including an AU repeat, that increased expression in bloodstream forms, or suppressed it in both forms. Trypanosome mRNAs that encode RNA-binding proteins often have extremely extended 3’-untranslated regions. We suggest that one function of this might be to act as a fail-safe mechanism to ensure correct regulation even if mRNA processing or expression of trans regulators is defective. The parasite Trypanosoma brucei causes sleeping sickness in humans, and nagana in cattle, and is transmitted by Tsetse flies. It grows in the bloodstream and tissue fluids of mammalian hosts, as "bloodstream forms", and as "procyclic forms" in the midgut of tsetse flies. Several hundred proteins are expressed in a stage-specific fashion, and this is essential for parasite survival in the different environments. RBP10 is an RNA-binding protein that is expressed only in bloodstream forms. It binds to procyclic-specific mRNAs, and causes their destruction. PGKC is an enzyme that is also specifically expressed in bloodstream forms. Developmental regulation of both is essential: expression of either RBP10 or PGKC in procyclic forms prevents their growth. The mRNAs encoding both proteins are very unstable in procyclic forms, and the sequences responsible are in an "untranslated region" of the mRNA—sequences that follow the part that codes for protein. We here show that the mRNA encoding PGKC has two regions that independently cause developmental regulation, and that the very long untranslated region of the RBP10 mRNA has no fewer than six regulatory regions, but there were no obvious similarities between them. We suggest that the presence of several different regulatory sequences in trypanosome mRNAs might be a fail-safe mechanism to ensure correct regulation.
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Affiliation(s)
| | - Lena Reichert
- Heidelberg University Center for Molecular Biology (ZMBH), Heidelberg, Germany
| | - Bin Liu
- Heidelberg University Center for Molecular Biology (ZMBH), Heidelberg, Germany
| | - Christine Clayton
- Heidelberg University Center for Molecular Biology (ZMBH), Heidelberg, Germany
- * E-mail:
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Cai XL, Li SJ, Zhang P, Li Z, Hide G, Lai DH, Lun ZR. The Occurrence of Malignancy in Trypanosoma brucei brucei by Rapid Passage in Mice. Front Microbiol 2022; 12:806626. [PMID: 35087505 PMCID: PMC8789148 DOI: 10.3389/fmicb.2021.806626] [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: 11/01/2021] [Accepted: 12/17/2021] [Indexed: 11/15/2022] Open
Abstract
Pleomorphic Trypanosoma brucei are best known for their tightly controlled cell growth and developmental program, which ensures their transmissibility and host fitness between the mammalian host and insect vector. However, after long-term adaptation in the laboratory or by natural evolution, monomorphic parasites can be derived. The origin of these monomorphic forms is currently unclear. Here, we produced a series of monomorphic trypanosome stocks by artificially syringe-passage in mice, creating snapshots of the transition from pleomorphism to monomorphism. We then compared these artificial monomorphic trypanosomes, alongside several naturally monomorphic T. evansi and T. equiperdum strains, with the pleomorphic T. brucei. In addition to failing to generate stumpy forms in animal bloodstream, we found that monomorphic trypanosomes from laboratory and nature exhibited distinct differentiation patterns, which are reflected by their distinct differentiation potential and transcriptional changes. Lab-adapted monomorphic trypanosomes could still be induced to differentiate, and showed only minor transcriptional differences to that of the pleomorphic slender forms but some accumulated differences were observed as the passages progress. All naturally monomorphic strains completely fail to differentiate, corresponding to their impaired differentiation regulation. We propose that the natural phenomenon of trypanosomal monomorphism is actually a malignant manifestation of protozoal cells. From a disease epidemiological and evolutionary perspective, our results provide evidence for a new way of thinking about the origin of these naturally monomorphic strains, the malignant evolution of trypanosomes may raise some concerns. Additionally, these monomorphic trypanosomes may reflect the quantitative and qualitative changes in the malignant evolution of T. brucei, suggesting that single-celled protozoa may also provide the most primitive model of cellular malignancy, which could be a primitive and inherent biological phenomenon of eukaryotic organisms from protozoans to mammals.
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Affiliation(s)
- Xiao-Li Cai
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Su-Jin Li
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Peng Zhang
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Ziyin Li
- Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Geoff Hide
- Biomedical Research Centre, School of Science, Engineering and Environment, University of Salford, Salford, United Kingdom
| | - De-Hua Lai
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Zhao-Rong Lun
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
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Abuchery BE, Black JA, da Silva MS. Single-cell transcriptomics reveals hidden information in trypanosomatids. Trends Parasitol 2021; 38:4-6. [PMID: 34774423 DOI: 10.1016/j.pt.2021.10.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 10/28/2021] [Indexed: 10/19/2022]
Abstract
Dixenic parasites often encounter environmental extremes during the transition from vector to host. Preadapted transmission stages overcome these challenges to promote parasites' survival and ensure life cycle progression. Recently, Vigneron et al. and Briggs et al. used single-cell transcriptomics to investigate developmental stage specific gene expression patterns during parasite differentiation.
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Affiliation(s)
- Bryan E Abuchery
- DNA Replication and Repair Laboratory, Department of Chemical and Biological Sciences, Institute of Biosciences, São Paulo State University (UNESP), Botucatu, SP, Brazil
| | - Jennifer A Black
- Faculty of Medicine of Ribeirão Preto, University of São Paulo, São Paulo, Brazil; The Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity, and Inflammation, University of Glasgow, Glasgow, UK
| | - Marcelo S da Silva
- DNA Replication and Repair Laboratory, Department of Chemical and Biological Sciences, Institute of Biosciences, São Paulo State University (UNESP), Botucatu, SP, Brazil.
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13
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Abstract
Abstract
In Trypanosoma brucei and related Kinetoplastids, regulation of gene expression occurs mostly post-transcriptionally, and RNA-binding proteins play a critical role in the regulation of mRNA and protein abundance. Trypanosoma brucei ZC3H28 is a 114 KDa cytoplasmic mRNA-binding protein with a single C(x)7C(x)5C(x)sH zinc finger at the C-terminus and numerous proline-, histidine- or glutamine-rich regions. ZC3H28 is essential for normal bloodstream-form trypanosome growth, and when tethered to a reporter mRNA, ZC3H28 increased reporter mRNA and protein levels. Purification of N-terminally tagged ZC3H28 followed by mass spectrometry showed enrichment of ribosomal proteins, various RNA-binding proteins including both poly(A) binding proteins, the translation initiation complex EIF4E4/EIF4G3, and the activator MKT1. Tagged ZC3H28 was preferentially associated with long RNAs that have low complexity sequences in their 3′-untranslated regions; their coding regions also have low ribosome densities. In agreement with the tethering results, after ZC3H28 depletion, the levels of a significant proportion of its bound mRNAs decreased. We suggest that ZC3H28 is implicated in the stabilization of long mRNAs that are poorly translated.
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14
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Steketee PC, Giordani F, Vincent IM, Crouch K, Achcar F, Dickens NJ, Morrison LJ, MacLeod A, Barrett MP. Transcriptional differentiation of Trypanosoma brucei during in vitro acquisition of resistance to acoziborole. PLoS Negl Trop Dis 2021; 15:e0009939. [PMID: 34752454 PMCID: PMC8648117 DOI: 10.1371/journal.pntd.0009939] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 12/06/2021] [Accepted: 10/21/2021] [Indexed: 11/19/2022] Open
Abstract
Subspecies of the protozoan parasite Trypanosoma brucei are the causative agents of Human African Trypanosomiasis (HAT), a debilitating neglected tropical disease prevalent across sub-Saharan Africa. HAT case numbers have steadily decreased since the start of the century, and sustainable elimination of one form of the disease is in sight. However, key to this is the development of novel drugs to combat the disease. Acoziborole is a recently developed benzoxaborole, currently in advanced clinical trials, for treatment of stage 1 and stage 2 HAT. Importantly, acoziborole is orally bioavailable, and curative with one dose. Recent studies have made significant progress in determining the molecular mode of action of acoziborole. However, less is known about the potential mechanisms leading to acoziborole resistance in trypanosomes. In this study, an in vitro-derived acoziborole-resistant cell line was generated and characterised. The AcoR line exhibited significant cross-resistance with the methyltransferase inhibitor sinefungin as well as hypersensitisation to known trypanocides. Interestingly, transcriptomics analysis of AcoR cells indicated the parasites had obtained a procyclic- or stumpy-like transcriptome profile, with upregulation of procyclin surface proteins as well as differential regulation of key metabolic genes known to be expressed in a life cycle-specific manner, even in the absence of major morphological changes. However, no changes were observed in transcripts encoding CPSF3, the recently identified protein target of acoziborole. The results suggest that generation of resistance to this novel compound in vitro can be accompanied by transcriptomic switches resembling a procyclic- or stumpy-type phenotype.
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Affiliation(s)
- Pieter C. Steketee
- The Roslin Institute, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian, United Kingdom
| | - Federica Giordani
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, United Kingdom
| | - Isabel M. Vincent
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, United Kingdom
| | - Kathryn Crouch
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, United Kingdom
| | - Fiona Achcar
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, United Kingdom
| | - Nicholas J. Dickens
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, United Kingdom
| | - Liam J. Morrison
- The Roslin Institute, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian, United Kingdom
| | - Annette MacLeod
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, United Kingdom
| | - Michael P. Barrett
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, United Kingdom
- Glasgow Polyomics, University of Glasgow, United Kingdom
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15
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Naguleswaran A, Fernandes P, Bevkal S, Rehmann R, Nicholson P, Roditi I. Developmental changes and metabolic reprogramming during establishment of infection and progression of Trypanosoma brucei brucei through its insect host. PLoS Negl Trop Dis 2021; 15:e0009504. [PMID: 34543277 PMCID: PMC8483307 DOI: 10.1371/journal.pntd.0009504] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 09/30/2021] [Accepted: 09/07/2021] [Indexed: 02/07/2023] Open
Abstract
Trypanosoma brucei ssp., unicellular parasites causing human and animal trypanosomiasis, are transmitted between mammals by tsetse flies. Periodic changes in variant surface glycoproteins (VSG), which form the parasite coat in the mammal, allow them to evade the host immune response. Different isolates of T. brucei show heterogeneity in their repertoires of VSG genes and have single nucleotide polymorphisms and indels that can impact on genome editing. T. brucei brucei EATRO1125 (AnTaR1 serodeme) is an isolate that is used increasingly often because it is pleomorphic in mammals and fly transmissible, two characteristics that have been lost by the most commonly used laboratory stocks. We present a genome assembly of EATRO1125, including contigs for the intermediate chromosomes and minichromosomes that serve as repositories of VSG genes. In addition, de novo transcriptome assemblies were performed using Illumina sequences from tsetse-derived trypanosomes. Reads of 150 bases enabled closely related members of multigene families to be discriminated. This revealed that the transcriptome of midgut-derived parasites is dynamic, starting with the expression of high affinity hexose transporters and glycolytic enzymes and then switching to proline uptake and catabolism. These changes resemble the transition from early to late procyclic forms in culture. Further metabolic reprogramming, including upregulation of tricarboxylic acid cycle enzymes, occurs in the proventriculus. Many transcripts upregulated in the salivary glands encode surface proteins, among them 7 metacyclic VSGs, multiple BARPs and GCS1/HAP2, a marker for gametes. A novel family of transmembrane proteins, containing polythreonine stretches that are predicted to be O-glycosylation sites, was also identified. Finally, RNA-Seq data were used to create an optimised annotation file with 5’ and 3’ untranslated regions accurately mapped for 9302 genes. We anticipate that this will be of use in identifying transcripts obtained by single cell sequencing technologies. Trypanosoma brucei ssp. are single-celled parasites that cause two tropical diseases: sleeping sickness in humans and nagana in domestic animals. Parasites survive in the host bloodstream because they periodically change their surface coats and also because they can switch from slender dividing forms to stumpy non-dividing forms. The latter can be transmitted to their second host, the tsetse fly. Although closely related, different geographical isolates differ in their repertoire of surface coats and have small, but important differences in their DNA sequences. In addition, laboratory strains that are transferred between mammals by needle passage lose the ability to produce stumpy forms and to infect flies. The isolate T. b. brucei EATRO1125 is often used for research as it produces stumpy forms and is fly transmissible. We provide an assembly of the genome of this isolate, including part of the repertoire of coat proteins, and a detailed analysis of the genes that the parasites express as they establish infection and progress through the fly. This has provided new insights into trypanosome biology. The combined genomic (DNA) and transcriptomic (RNA) data will be useful resources for the trypanosome research community.
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Affiliation(s)
| | - Paula Fernandes
- Institute of Cell Biology, University of Bern, Bern, Switzerland
- Graduate School of Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Shubha Bevkal
- Institute of Cell Biology, University of Bern, Bern, Switzerland
- Graduate School of Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Ruth Rehmann
- Institute of Cell Biology, University of Bern, Bern, Switzerland
| | - Pamela Nicholson
- Next Generation Sequencing Platform, University of Bern, Bern, Switzerland
| | - Isabel Roditi
- Institute of Cell Biology, University of Bern, Bern, Switzerland
- * E-mail:
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16
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Single-cell transcriptomic analysis of bloodstream Trypanosoma brucei reconstructs cell cycle progression and developmental quorum sensing. Nat Commun 2021; 12:5268. [PMID: 34489460 PMCID: PMC8421343 DOI: 10.1038/s41467-021-25607-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 08/17/2021] [Indexed: 02/07/2023] Open
Abstract
Developmental steps in the trypanosome life-cycle involve transition between replicative and non-replicative forms specialised for survival in, and transmission between, mammalian and tsetse fly hosts. Here, using oligopeptide-induced differentiation in vitro, we model the progressive development of replicative 'slender' to transmissible 'stumpy' bloodstream form Trypanosoma brucei and capture the transcriptomes of 8,599 parasites using single cell transcriptomics (scRNA-seq). Using this framework, we detail the relative order of biological events during asynchronous development, profile dynamic gene expression patterns and identify putative regulators. We additionally map the cell cycle of proliferating parasites and position stumpy cell-cycle exit at early G1 before progression to a distinct G0 state. A null mutant for one transiently elevated developmental regulator, ZC3H20 is further analysed by scRNA-seq, identifying its point of failure in the developmental atlas. This approach provides a paradigm for the dissection of differentiation events in parasites, relevant to diverse transitions in pathogen biology.
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17
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Genomics of Trypanosomatidae: Where We Stand and What Needs to Be Done? Pathogens 2021; 10:pathogens10091124. [PMID: 34578156 PMCID: PMC8472099 DOI: 10.3390/pathogens10091124] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 08/26/2021] [Accepted: 08/31/2021] [Indexed: 01/18/2023] Open
Abstract
Trypanosomatids are easy to cultivate and they are (in many cases) amenable to genetic manipulation. Genome sequencing has become a standard tool routinely used in the study of these flagellates. In this review, we summarize the current state of the field and our vision of what needs to be done in order to achieve a more comprehensive picture of trypanosomatid evolution. This will also help to illuminate the lineage-specific proteins and pathways, which can be used as potential targets in treating diseases caused by these parasites.
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18
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Mulindwa J, Ssentamu G, Matovu E, Kamanyi Marucha K, Aresta-Branco F, Helbig C, Clayton C. In vitro culture of freshly isolated Trypanosoma brucei brucei bloodstream forms results in gene copy-number changes. PLoS Negl Trop Dis 2021; 15:e0009738. [PMID: 34516555 PMCID: PMC8459984 DOI: 10.1371/journal.pntd.0009738] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 09/23/2021] [Accepted: 08/17/2021] [Indexed: 11/19/2022] Open
Abstract
Most researchers who study unicellular eukaryotes work with an extremely limited number of laboratory-adapted isolates that were obtained from the field decades ago, but the effects of passage in laboratory rodents, and adaptation to in vitro culture, have been little studied. For example, the vast majority of studies of Trypanosoma brucei biology have concentrated on just two strains, Lister 427 and EATRO1125, which were taken from the field over half a century ago and have since have undergone innumerable passages in rodents and culture. We here describe two new Trypanosoma brucei brucei strains. MAK65 and MAK98, which have undergone only 3 rodent passages since isolation from Ugandan cattle. High-coverage sequencing revealed that adaptation of the parasites to culture was accompanied by changes in gene copy numbers. T. brucei has so far been considered to be uniformly diploid, but we also found trisomy of chromosome 5 not only in one Lister 427 culture, but also in the MAK98 field isolate. Trisomy of chromosome 6, and increased copies of other chromosome segments, were also seen in established cultured lines. The two new T. brucei strains should be useful to researchers interested in trypanosome differentiation and pathogenicity. Initial results suggested that the two strains have differing infection patterns in rodents. MAK65 is uniformly diploid and grew more reproducibly in bloodstream-form culture than MAK98.
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Affiliation(s)
- Julius Mulindwa
- Department of Biochemistry and Sports Science, College of Natural Sciences, Makerere University, Kampala, Uganda
| | - Geofrey Ssentamu
- School of Biosecurity, Biotechnical and Laboratory Sciences, College of Veterinary Medicine, Animal Resources and Biosecurity, Makerere University, Kampala, Uganda
| | - Enock Matovu
- School of Biosecurity, Biotechnical and Laboratory Sciences, College of Veterinary Medicine, Animal Resources and Biosecurity, Makerere University, Kampala, Uganda
| | | | | | - Claudia Helbig
- Heidelberg University Centre for Molecular Biology (ZMBH), Heidelberg, Germany
| | - Christine Clayton
- Heidelberg University Centre for Molecular Biology (ZMBH), Heidelberg, Germany
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19
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Silva Pereira S, Jackson AP, Figueiredo LM. Evolution of the variant surface glycoprotein family in African trypanosomes. Trends Parasitol 2021; 38:23-36. [PMID: 34376326 DOI: 10.1016/j.pt.2021.07.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 07/21/2021] [Accepted: 07/22/2021] [Indexed: 01/22/2023]
Abstract
An intriguing and remarkable feature of African trypanosomes is their antigenic variation system, mediated by the variant surface glycoprotein (VSG) family and fundamental to both immune evasion and disease epidemiology within host populations. Recent studies have revealed that the VSG repertoire has a complex evolutionary history. Sequence diversity, genomic organization, and expression patterns are species-specific, which may explain other variations in parasite virulence and disease pathology. Evidence also shows that we may be underestimating the extent to what VSGs are repurposed beyond their roles as variant antigens, establishing a need to examine VSG functionality more deeply. Here, we review sequence variation within the VSG gene family, and highlight the many opportunities to explore their likely diverse contributions to parasite survival.
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Affiliation(s)
- Sara Silva Pereira
- Instituto de Medicina Molecular - João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Andrew P Jackson
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool L3 5RF, UK
| | - Luísa M Figueiredo
- Instituto de Medicina Molecular - João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal.
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20
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Abstract
African trypanosomes are responsible for important diseases of humans and animals in sub-Saharan Africa. The best-studied species is Trypanosoma brucei, which is characterized by development in the mammalian host between morphologically slender and stumpy forms. The latter are adapted for transmission by the parasite's vector, the tsetse fly. The development of stumpy forms is driven by density-dependent quorum-sensing (QS), the molecular basis for which is now coming to light. In this review, I discuss the historical context and biological features of trypanosome QS and how it contributes to the parasite's infection dynamics within its mammalian host. Also, I discuss how QS can be lost in different trypanosome species, such as T. brucei evansi and T. brucei equiperdum, or modulated when parasites find themselves competing with others of different genotypes or of different trypanosome species in the same host. Finally, I consider the potential to exploit trypanosome QS therapeutically. Expected final online publication date for the Annual Review of Microbiology, Volume 75 is October 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Keith R Matthews
- Institute for Immunology and Infection Research, Ashworth Laboratories, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3FL, United Kingdom;
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21
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Steketee PC, Dickie EA, Iremonger J, Crouch K, Paxton E, Jayaraman S, Alfituri OA, Awuah-Mensah G, Ritchie R, Schnaufer A, Rowan T, de Koning HP, Gadelha C, Wickstead B, Barrett MP, Morrison LJ. Divergent metabolism between Trypanosoma congolense and Trypanosoma brucei results in differential sensitivity to metabolic inhibition. PLoS Pathog 2021; 17:e1009734. [PMID: 34310651 PMCID: PMC8384185 DOI: 10.1371/journal.ppat.1009734] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 08/24/2021] [Accepted: 06/21/2021] [Indexed: 11/18/2022] Open
Abstract
Animal African Trypanosomiasis (AAT) is a debilitating livestock disease prevalent across sub-Saharan Africa, a main cause of which is the protozoan parasite Trypanosoma congolense. In comparison to the well-studied T. brucei, there is a major paucity of knowledge regarding the biology of T. congolense. Here, we use a combination of omics technologies and novel genetic tools to characterise core metabolism in T. congolense mammalian-infective bloodstream-form parasites, and test whether metabolic differences compared to T. brucei impact upon sensitivity to metabolic inhibition. Like the bloodstream stage of T. brucei, glycolysis plays a major part in T. congolense energy metabolism. However, the rate of glucose uptake is significantly lower in bloodstream stage T. congolense, with cells remaining viable when cultured in concentrations as low as 2 mM. Instead of pyruvate, the primary glycolytic endpoints are succinate, malate and acetate. Transcriptomics analysis showed higher levels of transcripts associated with the mitochondrial pyruvate dehydrogenase complex, acetate generation, and the glycosomal succinate shunt in T. congolense, compared to T. brucei. Stable-isotope labelling of glucose enabled the comparison of carbon usage between T. brucei and T. congolense, highlighting differences in nucleotide and saturated fatty acid metabolism. To validate the metabolic similarities and differences, both species were treated with metabolic inhibitors, confirming that electron transport chain activity is not essential in T. congolense. However, the parasite exhibits increased sensitivity to inhibition of mitochondrial pyruvate import, compared to T. brucei. Strikingly, T. congolense exhibited significant resistance to inhibitors of fatty acid synthesis, including a 780-fold higher EC50 for the lipase and fatty acid synthase inhibitor Orlistat, compared to T. brucei. These data highlight that bloodstream form T. congolense diverges from T. brucei in key areas of metabolism, with several features that are intermediate between bloodstream- and insect-stage T. brucei. These results have implications for drug development, mechanisms of drug resistance and host-pathogen interactions.
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Affiliation(s)
- Pieter C Steketee
- The Roslin Institute, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom
| | - Emily A Dickie
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - James Iremonger
- The Roslin Institute, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom
| | - Kathryn Crouch
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Edith Paxton
- The Roslin Institute, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom
| | - Siddharth Jayaraman
- The Roslin Institute, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom
| | - Omar A Alfituri
- The Roslin Institute, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom
| | | | - Ryan Ritchie
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Achim Schnaufer
- Institute of Immunology and Infection Research, University of Edinburgh, Edinburgh, United Kingdom
| | - Tim Rowan
- Global Alliance for Livestock Veterinary Medicines, Edinburgh, United Kingdom
| | - Harry P de Koning
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Catarina Gadelha
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Bill Wickstead
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Michael P Barrett
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom.,Glasgow Polyomics, University of Glasgow, Glasgow, United Kingdom
| | - Liam J Morrison
- The Roslin Institute, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom
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22
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Melo do Nascimento L, Egler F, Arnold K, Papavasiliou N, Clayton C, Erben E. Functional insights from a surface antigen mRNA-bound proteome. eLife 2021; 10:e68136. [PMID: 33783358 PMCID: PMC8051951 DOI: 10.7554/elife.68136] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Accepted: 03/18/2021] [Indexed: 01/13/2023] Open
Abstract
Trypanosoma brucei is the causative agent of human sleeping sickness. The parasites' variant surface glycoprotein (VSG) enables them to evade adaptive immunity via antigenic variation. VSG comprises 10% of total cell protein and the high stability of VSG mRNA is essential for trypanosome survival. To determine how VSG mRNA stability is maintained, we used mRNA affinity purification to identify all its associated proteins. CFB2 (cyclin F-box protein 2), an unconventional RNA-binding protein with an F-box domain, was specifically enriched with VSG mRNA. We demonstrate that CFB2 is essential for VSG mRNA stability, describe cis acting elements within the VSG 3'-untranslated region that regulate the interaction, identify trans-acting factors that are present in the VSG messenger ribonucleoprotein particle, and mechanistically explain how CFB2 stabilizes the mRNA of this key pathogenicity factor. Beyond T. brucei, the mRNP purification approach has the potential to supply detailed biological insight into metabolism of relatively abundant mRNAs in any eukaryote.
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Affiliation(s)
| | - Franziska Egler
- Centre for Molecular Biology of Heidelberg University (ZMBH)HeidelbergGermany
| | - Katharina Arnold
- Centre for Molecular Biology of Heidelberg University (ZMBH)HeidelbergGermany
| | - Nina Papavasiliou
- Division of Immune Diversity, Deutsche Krebsforschungszentrum (DKFZ)HeidelbergGermany
| | - Christine Clayton
- Centre for Molecular Biology of Heidelberg University (ZMBH)HeidelbergGermany
| | - Esteban Erben
- Centre for Molecular Biology of Heidelberg University (ZMBH)HeidelbergGermany
- Division of Immune Diversity, Deutsche Krebsforschungszentrum (DKFZ)HeidelbergGermany
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23
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Awuah-Mensah G, McDonald J, Steketee PC, Autheman D, Whipple S, D'Archivio S, Brandt C, Clare S, Harcourt K, Wright GJ, Morrison LJ, Gadelha C, Wickstead B. Reliable, scalable functional genetics in bloodstream-form Trypanosoma congolense in vitro and in vivo. PLoS Pathog 2021; 17:e1009224. [PMID: 33481935 PMCID: PMC7870057 DOI: 10.1371/journal.ppat.1009224] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 02/08/2021] [Accepted: 12/07/2020] [Indexed: 12/13/2022] Open
Abstract
Animal African trypanosomiasis (AAT) is a severe, wasting disease of domestic livestock and diverse wildlife species. The disease in cattle kills millions of animals each year and inflicts a major economic cost on agriculture in sub-Saharan Africa. Cattle AAT is caused predominantly by the protozoan parasites Trypanosoma congolense and T. vivax, but laboratory research on the pathogenic stages of these organisms is severely inhibited by difficulties in making even minor genetic modifications. As a result, many of the important basic questions about the biology of these parasites cannot be addressed. Here we demonstrate that an in vitro culture of the T. congolense genomic reference strain can be modified directly in the bloodstream form reliably and at high efficiency. We describe a parental single marker line that expresses T. congolense-optimized T7 RNA polymerase and Tet repressor and show that minichromosome loci can be used as sites for stable, regulatable transgene expression with low background in non-induced cells. Using these tools, we describe organism-specific constructs for inducible RNA-interference (RNAi) and demonstrate knockdown of multiple essential and non-essential genes. We also show that a minichromosomal site can be exploited to create a stable bloodstream-form line that robustly provides >40,000 independent stable clones per transfection-enabling the production of high-complexity libraries of genome-scale. Finally, we show that modified forms of T. congolense are still infectious, create stable high-bioluminescence lines that can be used in models of AAT, and follow the course of infections in mice by in vivo imaging. These experiments establish a base set of tools to change T. congolense from a technically challenging organism to a routine model for functional genetics and allow us to begin to address some of the fundamental questions about the biology of this important parasite.
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Affiliation(s)
| | - Jennifer McDonald
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Pieter C. Steketee
- The Roslin Institute, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom
| | - Delphine Autheman
- Cell Surface Signalling Laboratory, Wellcome Sanger Institute, Cambridge, United Kingdom
| | - Sarah Whipple
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Simon D'Archivio
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Cordelia Brandt
- Pathogen Support Team, Wellcome Sanger Institute, Cambridge, United Kingdom
| | - Simon Clare
- Pathogen Support Team, Wellcome Sanger Institute, Cambridge, United Kingdom
| | - Katherine Harcourt
- Pathogen Support Team, Wellcome Sanger Institute, Cambridge, United Kingdom
| | - Gavin J. Wright
- Cell Surface Signalling Laboratory, Wellcome Sanger Institute, Cambridge, United Kingdom
- Department of Biology, Hull York Medical School, York Biomedical Research Institute, University of York, York, United Kingdom
| | - Liam J. Morrison
- The Roslin Institute, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom
| | - Catarina Gadelha
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Bill Wickstead
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
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24
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Rojas-Pirela M, Andrade-Alviárez D, Rojas V, Kemmerling U, Cáceres AJ, Michels PA, Concepción JL, Quiñones W. Phosphoglycerate kinase: structural aspects and functions, with special emphasis on the enzyme from Kinetoplastea. Open Biol 2020; 10:200302. [PMID: 33234025 PMCID: PMC7729029 DOI: 10.1098/rsob.200302] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Phosphoglycerate kinase (PGK) is a glycolytic enzyme that is well conserved among the three domains of life. PGK is usually a monomeric enzyme of about 45 kDa that catalyses one of the two ATP-producing reactions in the glycolytic pathway, through the conversion of 1,3-bisphosphoglycerate (1,3BPGA) to 3-phosphoglycerate (3PGA). It also participates in gluconeogenesis, catalysing the opposite reaction to produce 1,3BPGA and ADP. Like most other glycolytic enzymes, PGK has also been catalogued as a moonlighting protein, due to its involvement in different functions not associated with energy metabolism, which include pathogenesis, interaction with nucleic acids, tumorigenesis progression, cell death and viral replication. In this review, we have highlighted the overall aspects of this enzyme, such as its structure, reaction kinetics, activity regulation and possible moonlighting functions in different protistan organisms, especially both free-living and parasitic Kinetoplastea. Our analysis of the genomes of different kinetoplastids revealed the presence of open-reading frames (ORFs) for multiple PGK isoforms in several species. Some of these ORFs code for unusually large PGKs. The products appear to contain additional structural domains fused to the PGK domain. A striking aspect is that some of these PGK isoforms are predicted to be catalytically inactive enzymes or ‘dead’ enzymes. The roles of PGKs in kinetoplastid parasites are analysed, and the apparent significance of the PGK gene duplication that gave rise to the different isoforms and their expression in Trypanosoma cruzi is discussed.
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Affiliation(s)
- Maura Rojas-Pirela
- Instituto de Biología, Facultad de Ciencias, Pontificia Universidad Católica de Valparaiso, Valparaiso 2373223, Chile
| | - Diego Andrade-Alviárez
- Laboratorio de Enzimología de Parásitos, Departamento de Biología, Facultad de Ciencias, Universidad de Los Andes, Mérida 5101, Venezuela
| | - Verónica Rojas
- Instituto de Biología, Facultad de Ciencias, Pontificia Universidad Católica de Valparaiso, Valparaiso 2373223, Chile
| | - Ulrike Kemmerling
- Instituto de Ciencias Biomédicas, Universidad de Chile, Facultad de Medicina, Santiago de Chile 8380453, Santigo de Chile
| | - Ana J Cáceres
- Laboratorio de Enzimología de Parásitos, Departamento de Biología, Facultad de Ciencias, Universidad de Los Andes, Mérida 5101, Venezuela
| | - Paul A Michels
- Centre for Immunity, Infection and Evolution, The King's Buildings, Edinburgh EH9 3FL, UK.,Centre for Translational and Chemical Biology, School of Biological Sciences, The University of Edinburgh, The King's Buildings, Edinburgh EH9 3FL, UK
| | - Juan Luis Concepción
- Laboratorio de Enzimología de Parásitos, Departamento de Biología, Facultad de Ciencias, Universidad de Los Andes, Mérida 5101, Venezuela
| | - Wilfredo Quiñones
- Laboratorio de Enzimología de Parásitos, Departamento de Biología, Facultad de Ciencias, Universidad de Los Andes, Mérida 5101, Venezuela
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25
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Grob D, Conejeros I, Velásquez ZD, Preußer C, Gärtner U, Alarcón P, Burgos RA, Hermosilla C, Taubert A. Trypanosoma brucei brucei Induces Polymorphonuclear Neutrophil Activation and Neutrophil Extracellular Traps Release. Front Immunol 2020; 11:559561. [PMID: 33193328 PMCID: PMC7649812 DOI: 10.3389/fimmu.2020.559561] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 08/18/2020] [Indexed: 12/12/2022] Open
Abstract
Trypanosoma brucei brucei trypomastigotes are classical blood parasites of cattle, these stages might become potential targets for circulating polymorphonuclear neutrophils (PMN). We here investigated NETs extrusion and related oxygen consumption in bovine PMN exposed to motile T. b. brucei trypomastigotes in vitro. Parasite exposure induced PMN activation as detected by enhanced oxygen consumption rates (OCR), extracellular acidification rates (ECAR), and production of total and extracellular reactive oxygen species (ROS). Scanning electron microscopy (SEM) showed that co-cultivation of bovine PMN with motile trypomastigotes resulted in NETs formation within 120 min of exposure. T. b. brucei-induced NETs were confirmed by confocal microscopy demonstrating co-localization of extruded DNA with neutrophil elastase (NE) and nuclear histones. Immunofluorescence analyses demonstrated that trypomastigotes induced different phenotypes of NETs in bovine PMN, such as aggregated NETs (aggNETs), spread NETs (sprNETs), and diffuse NETs (diffNETs) with aggNETs being the most abundant ones. Furthermore, live cell 3D-holotomographic microscopy unveiled detailed morphological changes during the NETotic process. Quantification of T. b. brucei-induced NETs formation was estimated by DNA and nuclear area analysis (DANA) and confirmed enhanced NETs formation in response to trypomastigote stages. Formation of NETs does not result in a decrease of T. b. brucei viability, but a decrease of 26% in the number of motile parasites. Referring the involved signaling pathways, trypomastigote-induced NETs formation seems to be purinergic-dependent, since inhibition via NF449 treatment resulted in a significant reduction of T. b. brucei-triggered DNA extrusion. Overall, future studies will have to analyze whether the formation of aggNETs indeed plays a role in the outcome of clinical disease and bovine African trypanosomiasis-related immunopathological disorders, such as increased intravascular coagulopathy and vascular permeability, often reported to occur in this disease.
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Affiliation(s)
- Daniela Grob
- Institute of Parasitology, Biomedical Research Center Seltersberg (BFS), Justus Liebig University Giessen, Giessen, Germany
| | - Iván Conejeros
- Institute of Parasitology, Biomedical Research Center Seltersberg (BFS), Justus Liebig University Giessen, Giessen, Germany
| | - Zahady D Velásquez
- Institute of Parasitology, Biomedical Research Center Seltersberg (BFS), Justus Liebig University Giessen, Giessen, Germany
| | - Christian Preußer
- Institute of Biochemistry, Department of Biology and Chemistry, Justus Liebig University Giessen, Giessen, Germany
| | - Ulrich Gärtner
- Institute of Anatomy and Cell Biology, Justus Liebig University Giessen, Giessen, Germany
| | - Pablo Alarcón
- Laboratory of Inflammation Pharmacology, Institute of Pharmacology and Morphophysiology, Universidad Austral de Chile, Valdivia, Chile
| | - Rafael A Burgos
- Laboratory of Inflammation Pharmacology, Institute of Pharmacology and Morphophysiology, Universidad Austral de Chile, Valdivia, Chile
| | - Carlos Hermosilla
- Institute of Parasitology, Biomedical Research Center Seltersberg (BFS), Justus Liebig University Giessen, Giessen, Germany
| | - Anja Taubert
- Institute of Parasitology, Biomedical Research Center Seltersberg (BFS), Justus Liebig University Giessen, Giessen, Germany
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26
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Bajak K, Leiss K, Clayton C, Erben E. A potential role for a novel ZC3H5 complex in regulating mRNA translation in Trypanosoma brucei. J Biol Chem 2020; 295:14291-14304. [PMID: 32763974 DOI: 10.1074/jbc.ra120.014346] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 07/29/2020] [Indexed: 11/06/2022] Open
Abstract
In Trypanosoma brucei and related kinetoplastids, gene expression regulation occurs mostly posttranscriptionally. Consequently, RNA-binding proteins play a critical role in the regulation of mRNA and protein abundance. Yet, the roles of many RNA-binding proteins are not understood. Our previous research identified the RNA-binding protein ZC3H5 as possibly involved in gene repression, but its role in controlling gene expression was unknown. We here show that ZC3H5 is an essential cytoplasmic RNA-binding protein. RNAi targeting ZC3H5 causes accumulation of precytokinetic cells followed by rapid cell death. Affinity purification and pairwise yeast two-hybrid analysis suggest that ZC3H5 forms a complex with three other proteins, encoded by genes Tb927.11.4900, Tb927.8.1500, and Tb927.7.3040. RNA immunoprecipitation revealed that ZC3H5 is preferentially associated with poorly translated, low-stability mRNAs, the 5'-untranslated regions and coding regions of which are enriched in the motif (U/A)UAG(U/A). As previously found in high-throughput analyses, artificial tethering of ZC3H5 to a reporter mRNA or other complex components repressed reporter expression. However, depletion of ZC3H5 in vivo caused only very minor decreases in a few targets, marked increases in the abundances of very stable mRNAs, an increase in monosomes at the expense of large polysomes, and appearance of "halfmer" disomes containing two 80S subunits and one 40S subunit. We speculate that the ZC3H5 complex might be implicated in quality control during the translation of suboptimal open reading frames.
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Affiliation(s)
- Kathrin Bajak
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), Heidelberg, Germany.,Deutsches Krebsforschungszentrum (DKFZ), Heidelberg, Germany
| | - Kevin Leiss
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), Heidelberg, Germany
| | - Christine Clayton
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), Heidelberg, Germany
| | - Esteban Erben
- Deutsches Krebsforschungszentrum (DKFZ), Heidelberg, Germany
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27
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Roles of the Pumilio domain protein PUF3 in Trypanosoma brucei growth and differentiation. Parasitology 2020; 147:1171-1183. [PMID: 32513341 DOI: 10.1017/s003118202000092x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Trypanosomes strongly rely on post-transcriptional mechanisms to control gene expression. Several Opisthokont Pumilio domain proteins are known to suppress expression when bound to mRNAs. The Trypanosoma brucei Pumilio domain protein PUF3 is a cytosolic mRNA-binding protein that suppresses expression when tethered to a reporter mRNA. RNA-binding studies showed that PUF3 preferentially binds to mRNAs with a classical Pumilio-domain recognition motif, UGUA[U/C]AUU. RNA-interference-mediated reduction of PUF3 in bloodstream forms caused a minor growth defect, but the transcriptome was not affected. Depletion of PUF3 also slightly delayed differentiation to the procyclic form. However, both PUF3 genes could be deleted in cultured bloodstream- and procyclic-form trypanosomes. Procyclic forms without PUF3 also grew somewhat slower than wild-type, but ectopic expression of C-terminally tagged PUF3 impaired their viability. PUF3 was not required for RBP10-induced differentiation of procyclic forms to bloodstream forms. Mass spectrometry revealed no PUF3 binding partners that might explain its suppressive activity. We conclude that PUF3 may have a role in fine-tuning gene expression. Since PUF3 is conserved in all Kinetoplastids, including those that do not infect vertebrates, we suggest that it might confer advantages within the invertebrate host.
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28
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Magez S, Pinto Torres JE, Obishakin E, Radwanska M. Infections With Extracellular Trypanosomes Require Control by Efficient Innate Immune Mechanisms and Can Result in the Destruction of the Mammalian Humoral Immune System. Front Immunol 2020; 11:382. [PMID: 32218784 PMCID: PMC7078162 DOI: 10.3389/fimmu.2020.00382] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 02/18/2020] [Indexed: 12/17/2022] Open
Abstract
Salivarian trypanosomes are extracellular parasites that affect humans, livestock, and game animals around the world. Through co-evolution with the mammalian immune system, trypanosomes have developed defense mechanisms that allow them to thrive in blood, lymphoid vessels, and tissue environments such as the brain, the fat tissue, and testes. Trypanosomes have developed ways to circumvent antibody-mediated killing and block the activation of the lytic arm of the complement pathway. Hence, this makes the innate immune control of the infection a crucial part of the host-parasite interaction, determining infection susceptibility, and parasitemia control. Indeed, trypanosomes use a combination of several independent mechanisms to avoid clearance by the humoral immune system. First, perpetuated antigenic variation of the surface coat allows to escape antibody-mediated elimination. Secondly, when antibodies bind to the coat, they are efficiently transported toward the endocytosis pathway, where they are removed from the coat proteins. Finally, trypanosomes engage in the active destruction of the mammalian humoral immune response. This provides them with a rescue solution in case antigenic variation does not confer total immunological invisibility. Both antigenic variation and B cell destruction pose significant hurdles for the development of anti-trypanosome vaccine strategies. However, developing total immune escape capacity and unlimited growth capabilities within a mammalian host is not beneficial for any parasite, as it will result in the accelerated death of the host itself. Hence, trypanosomes have acquired a system of quorum sensing that results in density-dependent population growth arrest in order to prevent overpopulating the host. The same system could possibly sense the infection-associated host tissue damage resulting from inflammatory innate immune responses, in which case the quorum sensing serves to prevent excessive immunopathology and as such also promotes host survival. In order to put these concepts together, this review summarizes current knowledge on the interaction between trypanosomes and the mammalian innate immune system, the mechanisms involved in population growth regulation, antigenic variation and the immuno-destructive effect of trypanosomes on the humoral immune system. Vaccine trials and a discussion on the role of innate immune modulation in these trials are discussed at the end.
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Affiliation(s)
- Stefan Magez
- Laboratory for Biomedical Research, Ghent University Global Campus, Incheon, South Korea.,Department of Biochemistry and Microbiology, Ghent University, Ghent, Belgium.,Laboratory of Cellular and Molecular Immunology, Vrije Universiteit Brussel, Brussels, Belgium
| | | | - Emmanuel Obishakin
- Laboratory for Biomedical Research, Ghent University Global Campus, Incheon, South Korea.,Biotechnology Division, National Veterinary Research Institute, Vom, Nigeria
| | - Magdalena Radwanska
- Laboratory for Biomedical Research, Ghent University Global Campus, Incheon, South Korea.,Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
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29
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Szöőr B, Silvester E, Matthews KR. A Leap Into the Unknown - Early Events in African Trypanosome Transmission. Trends Parasitol 2020; 36:266-278. [PMID: 32014419 DOI: 10.1016/j.pt.2019.12.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 11/19/2019] [Accepted: 12/25/2019] [Indexed: 01/09/2023]
Abstract
African trypanosomes are mainly transmitted by tsetse flies. In recent years there has been good progress in understanding how the parasites prepare for transmission, detect their changed environment through the perception of different environmental cues, and respond by changing their developmental gene expression. In this review, we discuss the different signals and signaling mechanisms used by the parasites to carry out the early events necessary for their establishment in the fly. We also compare Trypanosoma brucei and Trypanosoma congolense, parasites that share a common pathway in the early stages of fly colonization but apparently use different mechanisms to achieve this.
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Affiliation(s)
- Balázs Szöőr
- Institute for Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK.
| | - Eleanor Silvester
- Institute for Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK
| | - Keith R Matthews
- Institute for Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK.
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30
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Liu B, Kamanyi Marucha K, Clayton C. The zinc finger proteins ZC3H20 and ZC3H21 stabilise mRNAs encoding membrane proteins and mitochondrial proteins in insect-form Trypanosoma brucei. Mol Microbiol 2019; 113:430-451. [PMID: 31743541 DOI: 10.1111/mmi.14429] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 10/24/2019] [Accepted: 11/17/2019] [Indexed: 12/26/2022]
Abstract
ZC3H20 and ZC3H21 are related trypanosome proteins with two C(x)8 C(x)5 C(x)3 H zinc finger motifs. ZC3H20 is present at a low level in replicating mammalian-infective bloodstream forms, but becomes more abundant when they undergo growth arrest at high density; ZC3H21 appears only in the procyclic form of the parasite, which infects Tsetse flies. Each protein binds to several hundred mRNAs, with overlapping but not identical specificities. Both increase expression of bound mRNAs, probably through recruitment of the MKT1-PBP1 complex. At least 28 of the bound mRNAs decrease after depletion of ZC3H20, or of ZC3H20 and ZC3H21 together; their products include procyclic-specific proteins of the plasma membrane and energy metabolism. Simultaneous depletion of ZC3H20 and ZC3H21 causes procyclic forms to shrink and stop growing; in addition to decreases in target mRNAs, there are other changes suggestive of loss of developmental regulation. The bloodstream-form-specific protein RBP10 controls ZC3H20 and ZC3H21 expression. Interestingly, some ZC3H20/21 target mRNAs also bind to and are repressed by RBP10, allowing for dynamic regulation as RBP10 decreases and ZC3H20 and ZC3H21 increase during differentiation.
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Affiliation(s)
- Bin Liu
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Kevin Kamanyi Marucha
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Christine Clayton
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany
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31
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Cooper S, Wadsworth ES, Ochsenreiter T, Ivens A, Savill NJ, Schnaufer A. Assembly and annotation of the mitochondrial minicircle genome of a differentiation-competent strain of Trypanosoma brucei. Nucleic Acids Res 2019; 47:11304-11325. [PMID: 31665448 PMCID: PMC6868439 DOI: 10.1093/nar/gkz928] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 10/03/2019] [Accepted: 10/08/2019] [Indexed: 01/10/2023] Open
Abstract
Kinetoplastids are protists defined by one of the most complex mitochondrial genomes in nature, the kinetoplast. In the sleeping sickness parasite Trypanosoma brucei, the kinetoplast is a chain mail-like network of two types of interlocked DNA molecules: a few dozen ∼23-kb maxicircles (homologs of the mitochondrial genome of other eukaryotes) and thousands of ∼1-kb minicircles. Maxicircles encode components of respiratory chain complexes and the mitoribosome. Several maxicircle-encoded mRNAs undergo extensive post-transcriptional RNA editing via addition and deletion of uridines. The process is mediated by hundreds of species of minicircle-encoded guide RNAs (gRNAs), but the precise number of minicircle classes and gRNA genes was unknown. Here we present the first essentially complete assembly and annotation of the kinetoplast genome of T. brucei. We have identified 391 minicircles, encoding not only ∼930 predicted 'canonical' gRNA genes that cover nearly all known editing events (accessible via the web at http://hank.bio.ed.ac.uk), but also ∼370 'non-canonical' gRNA genes of unknown function. Small RNA transcriptome data confirmed expression of the majority of both categories of gRNAs. Finally, we have used our data set to refine definitions for minicircle structure and to explore dynamics of minicircle copy numbers.
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Affiliation(s)
- Sinclair Cooper
- Institute of Immunology & Infection Research, University of Edinburgh, Edinburgh, Scotland EH9 3FL, UK
| | - Elizabeth S Wadsworth
- Institute of Immunology & Infection Research, University of Edinburgh, Edinburgh, Scotland EH9 3FL, UK
| | | | - Alasdair Ivens
- Institute of Immunology & Infection Research, University of Edinburgh, Edinburgh, Scotland EH9 3FL, UK
| | - Nicholas J Savill
- Institute of Immunology & Infection Research, University of Edinburgh, Edinburgh, Scotland EH9 3FL, UK
| | - Achim Schnaufer
- Institute of Immunology & Infection Research, University of Edinburgh, Edinburgh, Scotland EH9 3FL, UK
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32
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Developmental competence and antigen switch frequency can be uncoupled in Trypanosoma brucei. Proc Natl Acad Sci U S A 2019; 116:22774-22782. [PMID: 31636179 PMCID: PMC6842576 DOI: 10.1073/pnas.1912711116] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Trypanosomes are blood-borne protozoa that cause human sleeping sickness and the livestock disease, nagana. These extracellular parasites sustain infection through their ability to change their surface proteins, a process called antigenic variation. They also promote their own transmission by development in the bloodstream to so-called “stumpy forms” generated in response to parasite density. Earlier studies have proposed that reduced capacity for stumpy formation also generates reduced antigen switch frequency, suggesting these processes are mechanistically coupled. Here, by silencing the density-sensing pathway or selecting parasites less able to generate stumpy forms, we demonstrate that these processes are under independent selection. This has relevance for parasite virulence, spread, and competition and for the selection of trypanosome species directly transmitted by biting flies. African trypanosomes use an extreme form of antigenic variation to evade host immunity, involving the switching of expressed variant surface glycoproteins by a stochastic and parasite-intrinsic process. Parasite development in the mammalian host is another feature of the infection dynamic, with trypanosomes undergoing quorum sensing (QS)-dependent differentiation between proliferative slender forms and arrested, transmissible, stumpy forms. Longstanding experimental studies have suggested that the frequency of antigenic variation and transmissibility may be linked, antigen switching being higher in developmentally competent, fly-transmissible, parasites (“pleomorphs”) than in serially passaged “monomorphic” lines that cannot transmit through flies. Here, we have directly tested this tenet of the infection dynamic by using 2 experimental systems to reduce pleomorphism. Firstly, lines were generated that inducibly lose developmental capacity through RNAi-mediated silencing of the QS signaling machinery (“inducible monomorphs”). Secondly, de novo lines were derived that have lost the capacity for stumpy formation by serial passage (“selected monomorphs”) and analyzed for their antigenic variation in comparison to isogenic preselected populations. Analysis of both inducible and selected monomorphs has established that antigen switch frequency and developmental capacity are independently selected traits. This generates the potential for diverse infection dynamics in different parasite populations where the rate of antigenic switching and transmission competence are uncoupled. Further, this may support the evolution, maintenance, and spread of important trypanosome variants such as Trypanosoma brucei evansi that exploit mechanical transmission.
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