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Ospina-Villa JD, Tovar-Ayona BJ, López-Camarillo C, Soto-Sánchez J, Ramírez-Moreno E, Castañón-Sánchez CA, Marchat LA. mRNA Polyadenylation Machineries in Intestinal Protozoan Parasites. J Eukaryot Microbiol 2020; 67:306-320. [PMID: 31898347 DOI: 10.1111/jeu.12781] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 12/16/2019] [Accepted: 12/22/2019] [Indexed: 12/22/2022]
Abstract
In humans, mRNA polyadenylation involves the participation of about 20 factors in four main complexes that recognize specific RNA sequences. Notably, CFIm25, CPSF73, and PAP have essential roles for poly(A) site selection, mRNA cleavage, and adenosine residues polymerization. Besides the relevance of polyadenylation for gene expression, information is scarce in intestinal protozoan parasites that threaten human health. To better understand polyadenylation in Entamoeba histolytica, Giardia lamblia, and Cryptosporidium parvum, which represent leading causes of diarrhea worldwide, genomes were screened for orthologs of human factors. Results showed that Entamoeba histolytica and C. parvum have 16 and 12 proteins out of the 19 human proteins used as queries, respectively, while G. lamblia seems to have the smallest polyadenylation machinery with only six factors. Remarkably, CPSF30, CPSF73, CstF77, PABP2, and PAP, which were found in all parasites, could represent the core polyadenylation machinery. Multiple genes were detected for several proteins in Entamoeba, while gene redundancy is lower in Giardia and Cryptosporidium. Congruently with their relevance in the polyadenylation process, CPSF73 and PAP are present in all parasites, and CFIm25 is only missing in Giardia. They conserve the functional domains and predicted folding of human proteins, suggesting they may have the same roles in polyadenylation.
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Affiliation(s)
- Juan David Ospina-Villa
- Independent Researcher, Transversal 27A Sur # 42-14, C.P. 055421, Envigado, Antioquia, Colombia
| | - Brisna Joana Tovar-Ayona
- Posgrados en Biomedicina Molecular y en Biotecnología, ENMH, Instituto Politécnico Nacional, Av. Guillermo Massieu Helguera 239, Col. La Escalera, Gustavo A. Madero, C.P. 07320, Ciudad de México, Mexico
| | - César López-Camarillo
- Posgrado en Ciencias Genómicas, Universidad Autónoma de la Ciudad de México, San Lorenzo 290, Col. del Valle Sur, Benito Juárez, C.P. 03100, Ciudad de México, Mexico
| | - Jacqueline Soto-Sánchez
- Posgrados en Biomedicina Molecular y en Biotecnología, ENMH, Instituto Politécnico Nacional, Av. Guillermo Massieu Helguera 239, Col. La Escalera, Gustavo A. Madero, C.P. 07320, Ciudad de México, Mexico
| | - Esther Ramírez-Moreno
- Posgrados en Biomedicina Molecular y en Biotecnología, ENMH, Instituto Politécnico Nacional, Av. Guillermo Massieu Helguera 239, Col. La Escalera, Gustavo A. Madero, C.P. 07320, Ciudad de México, Mexico
| | - Carlos A Castañón-Sánchez
- Hospital Regional de Alta Especialidad de Oaxaca, Aldama s/n, Col. Centro, C.P. 71256 San Bartolo Coyotepec, Oaxaca, Mexico
| | - Laurence A Marchat
- Posgrados en Biomedicina Molecular y en Biotecnología, ENMH, Instituto Politécnico Nacional, Av. Guillermo Massieu Helguera 239, Col. La Escalera, Gustavo A. Madero, C.P. 07320, Ciudad de México, Mexico
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Berná L, Chiribao ML, Greif G, Rodriguez M, Alvarez-Valin F, Robello C. Transcriptomic analysis reveals metabolic switches and surface remodeling as key processes for stage transition in Trypanosoma cruzi. PeerJ 2017; 5:e3017. [PMID: 28286708 PMCID: PMC5345387 DOI: 10.7717/peerj.3017] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 01/23/2017] [Indexed: 01/12/2023] Open
Abstract
American trypanosomiasis is a chronic and endemic disease which affects millions of people. Trypanosoma cruzi, its causative agent, has a life cycle that involves complex morphological and functional transitions, as well as a variety of environmental conditions. This requires a tight regulation of gene expression, which is achieved mainly by post-transcriptional regulation. In this work we conducted an RNAseq analysis of the three major life cycle stages of T. cruzi: amastigotes, epimastigotes and trypomastigotes. This analysis allowed us to delineate specific transcriptomic profiling for each stage, and also to identify those biological processes of major relevance in each state. Stage specific expression profiling evidenced the plasticity of T. cruzi to adapt quickly to different conditions, with particular focus on membrane remodeling and metabolic shifts along the life cycle. Epimastigotes, which replicate in the gut of insect vectors, showed higher expression of genes related to energy metabolism, mainly Krebs cycle, respiratory chain and oxidative phosphorylation related genes, and anabolism related genes associated to nucleotide and steroid biosynthesis; also, a general down-regulation of surface glycoprotein coding genes was seen at this stage. Trypomastigotes, living extracellularly in the bloodstream of mammals, express a plethora of surface proteins and signaling genes involved in invasion and evasion of immune response. Amastigotes mostly express membrane transporters and genes involved in regulation of cell cycle, and also express a specific subset of surface glycoprotein coding genes. In addition, these results allowed us to improve the annotation of the Dm28c genome, identifying new ORFs and set the stage for construction of networks of co-expression, which can give clues about coded proteins of unknown functions.
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Affiliation(s)
- Luisa Berná
- Unidad de Biología Molecular, Institut Pasteur de Montevideo, Montevideo, Uruguay
| | - Maria Laura Chiribao
- Unidad de Biología Molecular, Institut Pasteur de Montevideo, Montevideo, Uruguay.,Departamento de Bioquímica, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - Gonzalo Greif
- Unidad de Biología Molecular, Institut Pasteur de Montevideo, Montevideo, Uruguay
| | - Matias Rodriguez
- Sección Biomatemática, Unidad de Genómica Evolutiva, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
| | - Fernando Alvarez-Valin
- Sección Biomatemática, Unidad de Genómica Evolutiva, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
| | - Carlos Robello
- Unidad de Biología Molecular, Institut Pasteur de Montevideo, Montevideo, Uruguay.,Departamento de Bioquímica, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
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Li Y, Shah-Simpson S, Okrah K, Belew AT, Choi J, Caradonna KL, Padmanabhan P, Ndegwa DM, Temanni MR, Corrada Bravo H, El-Sayed NM, Burleigh BA. Transcriptome Remodeling in Trypanosoma cruzi and Human Cells during Intracellular Infection. PLoS Pathog 2016; 12:e1005511. [PMID: 27046031 PMCID: PMC4821583 DOI: 10.1371/journal.ppat.1005511] [Citation(s) in RCA: 116] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 02/28/2016] [Indexed: 01/22/2023] Open
Abstract
Intracellular colonization and persistent infection by the kinetoplastid protozoan parasite, Trypanosoma cruzi, underlie the pathogenesis of human Chagas disease. To obtain global insights into the T. cruzi infective process, transcriptome dynamics were simultaneously captured in the parasite and host cells in an infection time course of human fibroblasts. Extensive remodeling of the T. cruzi transcriptome was observed during the early establishment of intracellular infection, coincident with a major developmental transition in the parasite. Contrasting this early response, few additional changes in steady state mRNA levels were detected once mature T. cruzi amastigotes were formed. Our findings suggest that transcriptome remodeling is required to establish a modified template to guide developmental transitions in the parasite, whereas homeostatic functions are regulated independently of transcriptomic changes, similar to that reported in related trypanosomatids. Despite complex mechanisms for regulation of phenotypic expression in T. cruzi, transcriptomic signatures derived from distinct developmental stages mirror known or projected characteristics of T. cruzi biology. Focusing on energy metabolism, we were able to validate predictions forecast in the mRNA expression profiles. We demonstrate measurable differences in the bioenergetic properties of the different mammalian-infective stages of T. cruzi and present additional findings that underscore the importance of mitochondrial electron transport in T. cruzi amastigote growth and survival. Consequences of T. cruzi colonization for the host include dynamic expression of immune response genes and cell cycle regulators with upregulation of host cholesterol and lipid synthesis pathways, which may serve to fuel intracellular T. cruzi growth. Thus, in addition to the biological inferences gained from gene ontology and functional enrichment analysis of differentially expressed genes in parasite and host, our comprehensive, high resolution transcriptomic dataset provides a substantially more detailed interpretation of T. cruzi infection biology and offers a basis for future drug and vaccine discovery efforts. In-depth knowledge of the functional processes governing host colonization and transmission of pathogenic microorganisms is essential for the advancement of effective intervention strategies. This study focuses on Trypanosoma cruzi, the vector-borne protozoan parasite responsible for human Chagas disease and the leading cause of infectious myocarditis worldwide. To gain global insights into the biology of this parasite and its interaction with mammalian host cells, we have exploited a deep-sequencing approach to generate comprehensive, high-resolution transcriptomic maps for mammalian-infective stages of T. cruzi with the simultaneous interrogation of the human host cell transcriptome across an infection time course. We demonstrate that the establishment of intracellular T. cruzi infection in mammalian host cells is accompanied by extensive remodeling of the parasite and host cell transcriptomes. Despite the lack of transcriptional control mechanisms in trypanosomatids, our analyses identified functionally-enriched processes within sets of developmentally-regulated transcripts in T. cruzi that align with known or predicted biological features of the parasite. The novel insights into the biology of intracellular T. cruzi infection and the regulation of amastigote development gained in this study establish a unique foundation for functional network analyses that will be instrumental in providing functional links between parasite dependencies and host functional pathways that have the potential to be exploited for intervention.
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Affiliation(s)
- Yuan Li
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, United States of America
| | - Sheena Shah-Simpson
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts, United States of America
| | - Kwame Okrah
- Center for Bioinformatics and Computational Biology, University of Maryland, College Park, Maryland, United States of America
| | - A Trey Belew
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, United States of America
| | - Jungmin Choi
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, United States of America
| | - Kacey L Caradonna
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts, United States of America
| | - Prasad Padmanabhan
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts, United States of America
| | - David M Ndegwa
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts, United States of America
| | - M Ramzi Temanni
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, United States of America
| | - Héctor Corrada Bravo
- Center for Bioinformatics and Computational Biology, University of Maryland, College Park, Maryland, United States of America
| | - Najib M El-Sayed
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, United States of America.,Center for Bioinformatics and Computational Biology, University of Maryland, College Park, Maryland, United States of America
| | - Barbara A Burleigh
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts, United States of America
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Metabolic reprogramming during purine stress in the protozoan pathogen Leishmania donovani. PLoS Pathog 2014; 10:e1003938. [PMID: 24586154 PMCID: PMC3937319 DOI: 10.1371/journal.ppat.1003938] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Accepted: 01/06/2014] [Indexed: 01/18/2023] Open
Abstract
The ability of Leishmania to survive in their insect or mammalian host is dependent upon an ability to sense and adapt to changes in the microenvironment. However, little is known about the molecular mechanisms underlying the parasite response to environmental changes, such as nutrient availability. To elucidate nutrient stress response pathways in Leishmania donovani, we have used purine starvation as the paradigm. The salvage of purines from the host milieu is obligatory for parasite replication; nevertheless, purine-starved parasites can persist in culture without supplementary purine for over three months, indicating that the response to purine starvation is robust and engenders parasite survival under conditions of extreme scarcity. To understand metabolic reprogramming during purine starvation we have employed global approaches. Whole proteome comparisons between purine-starved and purine-replete parasites over a 6–48 h span have revealed a temporal and coordinated response to purine starvation. Purine transporters and enzymes involved in acquisition at the cell surface are upregulated within a few hours of purine removal from the media, while other key purine salvage components are upregulated later in the time-course and more modestly. After 48 h, the proteome of purine-starved parasites is extensively remodeled and adaptations to purine stress appear tailored to deal with both purine deprivation and general stress. To probe the molecular mechanisms affecting proteome remodeling in response to purine starvation, comparative RNA-seq analyses, qRT-PCR, and luciferase reporter assays were performed on purine-starved versus purine-replete parasites. While the regulation of a minority of proteins tracked with changes at the mRNA level, for many regulated proteins it appears that proteome remodeling during purine stress occurs primarily via translational and/or post-translational mechanisms. Leishmania, the cause of a deadly spectrum of diseases in humans, surmounts a number of environmental challenges, including changes in the availability of salvageable nutrients, to successfully colonize its host. Adaptation to environmental stress is clearly of significance in parasite biology, but the underlying mechanisms are not well understood. To simulate the response to periodic nutrient scarcity in vivo, we have induced purine starvation in vitro. Purines are essential for growth and viability, and serve as the major energy currency of cells. Leishmania cannot synthesize purines and must salvage them from the surroundings. Extracellular purine depletion in culture induces a robust survival response in Leishmania, whereby growth arrests, but parasites persist for months. To profile the events that enable endurance of purine starvation, we used shotgun proteomics. Our data suggest that purine starvation induces extensive proteome remodeling, tailored to enhance purine capture and recycling, reduce energy expenditures, and maintain viability of the metabolically active, non-dividing population. Through global and targeted approaches, we reveal that proteome remodeling is multifaceted, and occurs through an array of responses at the mRNA, translational, and post-translational level. Our data provide one of the most inclusive views of adaptation to microenvironmental stress in Leishmania.
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Oliveira IA, Freire-de-Lima L, Penha LL, Dias WB, Todeschini AR. Trypanosoma cruzi Trans-sialidase: structural features and biological implications. Subcell Biochem 2014; 74:181-201. [PMID: 24264246 DOI: 10.1007/978-94-007-7305-9_8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Trypanosoma cruzi trans-sialidase (TcTS) has intrigued researchers all over the world since it was shown that T. cruzi incorporates sialic acid through a mechanism independent of sialyltransferases. The enzyme has being involved in a vast myriad of functions in the biology of the parasite and in the pathology of Chagas' disease. At the structural level experiments trapping the intermediate with fluorosugars followed by peptide mapping, X-ray crystallography, molecular modeling and magnetic nuclear resonance have opened up a three-dimensional understanding of the way this enzyme works. Herein we review the multiple biological roles of TcTS and the structural studies that are slowly revealing the secrets underlining an efficient sugar transfer activity rather than simple hydrolysis by TcTS.
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Affiliation(s)
- Isadora A Oliveira
- Laboratório de Glicobiologia Estrutural e Funcional, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Avenida Carlos Chagas Filho, 373, Centro de Ciências da Saúde-Bloco D-3, 21941-902, Cidade Universitária, Rio de Janeiro, Brazil
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6
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Goyard S, Dutra PL, Deolindo P, Autheman D, D'Archivio S, Minoprio P. In vivo imaging of trypanosomes for a better assessment of host-parasite relationships and drug efficacy. Parasitol Int 2013; 63:260-8. [PMID: 23892180 DOI: 10.1016/j.parint.2013.07.011] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Revised: 05/20/2013] [Accepted: 07/16/2013] [Indexed: 11/19/2022]
Abstract
The advances in microscopy combined to the invaluable progress carried by the utilization of molecular, immunological or immunochemical markers and the implementation of more powerful imaging technologies have yielded great improvements to the knowledge of the interaction between microorganisms and their hosts, notably a better understanding of the establishment of infectious processes. Still today, the intricacies of the dialog between parasites, cells and tissues remain limited. Some improvements have been attained with the stable integration and expression of the green fluorescence protein or firefly luciferase and other reporter genes, which have allowed to better approach the monitoring of gene expression and protein localization in vivo, in situ and in real time. Aiming at better exploring the well-established models of murine infections with the characterized strains of Trypanosoma cruzi and Trypanosoma vivax, we revisited in the present report the state of the art about the tools for the imaging of Trypanosomatids in vitro and in vivo and show the latest transgenic parasites that we have engineered in our laboratory using conventional transfection methods. The targeting of trypanosomes presented in this study is a promising tool for approaching the biology of parasite interactions with host cells, the progression of the diseases they trigger and the screening of new drugs in vivo or in vitro.
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Affiliation(s)
- S Goyard
- Institut Pasteur, Laboratoire des Processus Infectieux à Trypanosomatidés, Département Infection et Epidemiologie, 25 rue du Dr. Roux, 75724 Paris, France
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Pastro L, Smircich P, Pérez-Díaz L, Duhagon MA, Garat B. Implication of CA repeated tracts on post-transcriptional regulation in Trypanosoma cruzi. Exp Parasitol 2013; 134:511-8. [PMID: 23631879 DOI: 10.1016/j.exppara.2013.04.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Revised: 04/13/2013] [Accepted: 04/19/2013] [Indexed: 10/26/2022]
Abstract
In Trypanosoma cruzi gene expression regulation mainly relays on post-transcriptional events. Nevertheless, little is known about the signals which control mRNA abundance and functionality. We have previously found that CA repeated tracts (polyCA) are abundant in the vicinity of open reading frames and constitute specific targets for single stranded binding proteins from T. cruzi epimastigote. Given the reported examples of the involvement of polyCA motifs in gene expression regulation, we decided to further study their role in T. cruzi. Using an in silico genome-wide analysis, we identify the genes that contain polyCA within their predicted UTRs. We found that about 10% of T. cruzi genes carry polyCA therein. Strikingly, they are frequently concurrent with GT repeated tracts (polyGT), favoring the formation of a secondary structure exhibiting the complementary polydinucleotides in a double stranded helix. This feature is found in the species-specific family of genes coding for mucine associated proteins (MASPs) and other genes. For those polyCA-containing UTRs that lack polyGT, the polyCA is mainly predicted to adopt a single stranded structure. We further analyzed the functional role of such element using a reporter approach in T. cruzi. We found out that the insertion of polyCA at the 3' UTR of a reporter gene in the pTEX vector modulates its expression along the parasite's life cycle. While no significant change of the mRNA steady state of the reporter gene could be detected at the trypomastigote stage, significant increase in the epimastigote and reduction in the amastigote stage were observed. Altogether, these results suggest the involvement of polyCA as a signal in gene expression regulation in T. cruzi.
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Affiliation(s)
- Lucía Pastro
- Laboratorio de Interacciones Moleculares, Facultad de Ciencias, 11400 Montevideo, Uruguay
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Correa PRC, Cordero EM, Gentil LG, Bayer-Santos E, da Silveira JF. Genetic structure and expression of the surface glycoprotein GP82, the main adhesin of Trypanosoma cruzi metacyclic trypomastigotes. ScientificWorldJournal 2013; 2013:156734. [PMID: 23431251 PMCID: PMC3575623 DOI: 10.1155/2013/156734] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Accepted: 12/30/2012] [Indexed: 01/10/2023] Open
Abstract
T. cruzi improves the likelihood of invading or adapting to the host through its capacity to present a large repertoire of surface molecules. The metacyclic stage-specific surface glycoprotein GP82 has been implicated in host cell invasion. GP82 is encoded by multiple genes from the trans-sialidase superfamily. GP82 shows a modular organization, with some variation of N-terminal region flanking a conserved central core where the binding sites to the mammalian cell and gastric mucin are located. The function of GP82 as adhesin in host cell invasion process could expose the protein to an intense conservative and selective pressure. GP82 is a GPI-anchored surface protein, synthesized as a 70 kDa precursor devoid of N-linked sugars. GPI-minus variants accumulate in the ER indicating that GPI anchor acts as a forward transport signal for progressing along the secretory pathway as suggested for T. cruzi mucins. It has been demonstrated that the expression of GP82 is constitutive and may be regulated at post-transcriptional level, for instance, at translational level and/or mRNA stabilization. GP82 mRNAs are mobilized to polysomes and consequently translated, but only in metacyclic trypomastigotes. Analysis of transgenic parasites indicates that the mechanism regulating GP82 expression involves multiple elements in the 3'UTR.
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Affiliation(s)
- Paulo Roberto Ceridorio Correa
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, Rua Botucatu 862, 04023-062 São Paulo, SP, Brazil
| | - Esteban Mauricio Cordero
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, Rua Botucatu 862, 04023-062 São Paulo, SP, Brazil
| | - Luciana Girotto Gentil
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, Rua Botucatu 862, 04023-062 São Paulo, SP, Brazil
| | - Ethel Bayer-Santos
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, Rua Botucatu 862, 04023-062 São Paulo, SP, Brazil
| | - José Franco da Silveira
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, Rua Botucatu 862, 04023-062 São Paulo, SP, Brazil
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Bayer-Santos E, Gentil LG, Cordero EM, Corrêa PRC, da Silveira JF. Regulatory elements in the 3' untranslated region of the GP82 glycoprotein are responsible for its stage-specific expression in Trypanosoma cruzi metacyclic trypomastigotes. Acta Trop 2012; 123:230-3. [PMID: 22579673 DOI: 10.1016/j.actatropica.2012.03.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Revised: 03/13/2012] [Accepted: 03/14/2012] [Indexed: 11/29/2022]
Abstract
Gene expression in Trypanosoma cruzi is regulated at the post-transcriptional level and cis-acting elements present in the 3' untranslated region (3'UTR) play an important role by interacting with regulatory proteins. Previous studies demonstrated that the GP82 surface glycoprotein, which is involved in host cell invasion, is up-regulated in the infective metacyclic trypomastigote form, and that GP82 mRNA half-life is longer in this form compared to the non-infective epimastigote form. Here, we demonstrate that the 3'UTR of the GP82 transcript is involved in this developmental regulation, promoting higher expression of the green fluorescent protein (GFP) reporter in metacyclic trypomastigotes than in epimastigotes. A series of stepwise deletions in the 3'UTR was created and results suggest that the mechanism regulating GP82 expression involves multiple elements in the 3'UTR.
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Affiliation(s)
- Ethel Bayer-Santos
- Departamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de São Paulo, UNIFESP, Rua Botucatu 862, CEP 04023-062 São Paulo, Brazil
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Experimental chemotherapy and approaches to drug discovery for Trypanosoma cruzi infection. ADVANCES IN PARASITOLOGY 2011; 75:89-119. [PMID: 21820553 DOI: 10.1016/b978-0-12-385863-4.00005-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
In the 100 years since the discovery of Chagas disease, only two drugs have been developed and introduced into clinical practice, and these drugs were introduced over 40 years ago. The tools of drug discovery have improved dramatically in the interim; however, this has not translated into new drugs for Chagas disease. This has been largely because the main practitioners of drug discovery are pharmaceutical companies who are not financially motivated to invest in Chagas disease and other "orphan" diseases. As a result, it has largely been up to academic groups to bring drug candidates through the discovery pipeline and to clinical trials. The difficulty with drug discovery in academia has been the challenge of bringing together the diverse expertise in biology, chemistry, and pharmacology in concerted efforts towards a common goal of developing therapeutics. Funding is often inadequate, but lack of coordination amongst academic investigators with different expertise has also contributed to the slow progress. The purpose of this chapter is to provide an overview of approaches that can be accomplished in academic settings for preclinical drug discovery for Chagas disease. The chapter addresses methods of drug screening against Trypanosoma cruzi cultures and in animal models and includes general topics on compound selection, testing for drug-like properties (including oral bioavailability), investigating the pharmacokinetics and toxicity of compounds, and finally providing parameters to help with triaging compounds.
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Araújo PR, Teixeira SM. Regulatory elements involved in the post-transcriptional control of stage-specific gene expression in Trypanosoma cruzi: a review. Mem Inst Oswaldo Cruz 2011; 106:257-66. [PMID: 21655811 DOI: 10.1590/s0074-02762011000300002] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2011] [Accepted: 04/07/2011] [Indexed: 11/22/2022] Open
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Development of a dual reporter system to identify regulatory cis-acting elements in untranslated regions of Trypanosoma cruzi mRNAs. Parasitol Int 2011; 60:161-9. [PMID: 21277385 DOI: 10.1016/j.parint.2011.01.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2010] [Revised: 01/19/2011] [Accepted: 01/20/2011] [Indexed: 01/26/2023]
Abstract
In trypanosomatids, transcription is polycistronic and gene expression control occurs mainly at the post-transcriptional level. To investigate the role of sequences present in the 3'UTR of stage-specific mRNAs of Trypanosoma cruzi, we generated a new vector, named pTcDUALuc, containing the firefly and Renilla luciferase reporter genes. To test this vector, sequences derived from the 3'UTR plus intergenic regions of the alpha tubulin gene, which is up-regulated in epimastigotes, and amastin, which is up-regulated in amastigotes, were inserted downstream from the firefly reporter gene and luciferase activity was compared in transient and stable transfected parasites. As expected, increased luciferase activity was detected in epimastigotes transiently transfected with pTcDUALuc containing tubulin sequences. Using stable transfected cell lines that were allowed to differentiate into amastigotes, we observed increased luciferase activity and mRNA levels in amastigotes transfected with pTcDUALuc containing amastin sequences. We also showed that the spliced leader sequence and poly-A tail were inserted in the predicted sites of the firefly luciferase mRNA and that deletions in the alpha tubulin 3'UTR resulted in decreased luciferase expression because it affects polyadenylation. In contrast to the constructs containing 3'UTR sequences derived from tubulin and amastin genes, the presence of the 3'UTR from a trans-sialidase gene, whose expression is higher in trypomastigotes, resulted in increased luciferase activity in trypomastigotes without a corresponding increase in luciferase mRNA levels.
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Goldenberg S, Ávila AR. Aspects of Trypanosoma cruzi stage differentiation. ADVANCES IN PARASITOLOGY 2011; 75:285-305. [PMID: 21820561 DOI: 10.1016/b978-0-12-385863-4.00013-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Trypanosoma cruzi alternates between different morphological and functional types during its life cycle. Since the discovery of this parasite at the beginning of the twentieth century, efforts have been made to determine the basis of its pathogenesis in the course of Chagas disease and its biochemical constituents. There has also been work to develop tools and strategies for prophylaxis of the important disease caused by these parasites which affects millions of people in Latin America. The identification of axenic conditions allowing T. cruzi growth and differentiation has led to the identification and characterization of stage-specific antigens as well as a better characterization of the biological properties and biochemical particularities of each individual developmental stage. The recent availability of genomic data should pave the way to new progress in our knowledge of the biology and pathogenesis of T. cruzi. This review addresses the differentiation and major stage-specific antigens of T. cruzi and attempts to describe the complexity of the parasite and of the disease it causes.
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14
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García EA, Ziliani M, Agüero F, Bernabó G, Sánchez DO, Tekiel V. TcTASV: a novel protein family in trypanosoma cruzi identified from a subtractive trypomastigote cDNA library. PLoS Negl Trop Dis 2010; 4. [PMID: 20957201 PMCID: PMC2950142 DOI: 10.1371/journal.pntd.0000841] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2010] [Accepted: 09/07/2010] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND The identification and characterization of antigens expressed in Trypanosoma cruzi stages that parasitize mammals are essential steps for the development of new vaccines and diagnostics. Genes that are preferentially expressed in trypomastigotes may be involved in key processes that define the biology of trypomastigotes, like cell invasion and immune system evasion. METHODOLOGY/PRINCIPAL FINDINGS With the initial aim of identifying trypomastigote-specific expressed tags, we constructed and sequenced an epimastigote-subtracted trypomastigote cDNA library (library TcT-E). More than 45% of the sequenced clones of the library could not be mapped to previously annotated mRNAs or proteins. We validated the presence of these transcripts by reverse northern blot and northern blot experiments, therefore providing novel information about the mRNA expression of these genes in trypomastigotes. A 280-bp consensus element (TcT-E element, TcT-Eelem) located at the 3' untranslated region (3' UTR) of many different open reading frames (ORFs) was identified after clustering the TcT-E dataset. Using an RT-PCR approach, we were able to amplify different mature mRNAs containing the same TcT-Eelem in the 3' UTR. The proteins encoded by these ORFs are members of a novel surface protein family in T. cruzi, (which we named TcTASV for T. cruzi Trypomastigote, Alanine, Serine and Valine rich proteins). All members of the TcTASV family have conserved coding amino- and carboxy-termini, and a central variable core that allows partitioning of TcTASV proteins into three subfamilies. Analysis of the T. cruzi genome database resulted in the identification of 38 genes/ORFs for the whole TcTASV family in the reference CL-Brener strain (lineage II). Because this protein family was not found in other trypanosomatids, we also looked for the presence of TcTASV genes in other evolutionary lineages of T. cruzi, sequencing 48 and 28 TcTASVs members from the RA (lineage II) and Dm28 (lineage I) T. cruzi strains respectively. Detailed phylogenetic analyses of TcTASV gene products show that this gene family is different from previously characterized mucin (TcMUCII), mucin-like, and MASP protein families. CONCLUSIONS/SIGNIFICANCE We identified TcTASV, a new gene family of surface proteins in T. cruzi.
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Affiliation(s)
- Elizabeth A. García
- Instituto de Investigaciones Biotecnológicas (IIB-Intech), Universidad Nacional de General San Martín – CONICET, Buenos Aires, Argentina
| | - María Ziliani
- Instituto de Investigaciones Biotecnológicas (IIB-Intech), Universidad Nacional de General San Martín – CONICET, Buenos Aires, Argentina
| | - Fernán Agüero
- Instituto de Investigaciones Biotecnológicas (IIB-Intech), Universidad Nacional de General San Martín – CONICET, Buenos Aires, Argentina
| | - Guillermo Bernabó
- Instituto de Investigaciones Biotecnológicas (IIB-Intech), Universidad Nacional de General San Martín – CONICET, Buenos Aires, Argentina
| | - Daniel O. Sánchez
- Instituto de Investigaciones Biotecnológicas (IIB-Intech), Universidad Nacional de General San Martín – CONICET, Buenos Aires, Argentina
| | - Valeria Tekiel
- Instituto de Investigaciones Biotecnológicas (IIB-Intech), Universidad Nacional de General San Martín – CONICET, Buenos Aires, Argentina
- * E-mail:
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15
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Brandão A, Jiang T. The composition of untranslated regions in Trypanosoma cruzi genes. Parasitol Int 2009; 58:215-9. [PMID: 19505588 DOI: 10.1016/j.parint.2009.06.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2009] [Revised: 05/26/2009] [Accepted: 06/01/2009] [Indexed: 11/25/2022]
Abstract
We collected the UTRs from Trypanosomacruzi genes that have been experimentally mapped and are publicly available, and made a comprehensive analysis of their composition features including sequence length, G+C content and relationship to ORF, composition of the most frequent words, and distribution of Simple Sequence Repeats (SSR). T. cruzi UTRs exhibit range length of 10-400bp for 5' UTR and 17-2800 for 3' UTR. Both UTRs display mean G+C content of 40%. Ratios between the UTR and protein coding segments show that the 5' UTR is limited to a maximum of 20% of the total length in the final transcript. The 5' UTR most frequent words in the range 4-12 bases are almost exact complement to the 3' UTR respective words. SSR in 3' UTR are longer than in 5' UTR and are mostly derived from TA/AT, TG/GT, and TTA/ATT. SSR accounts up to 20% of the nucleotide composition in 5' UTR and up to 90% in the 3' UTR.
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16
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Bartholomeu DC, Cerqueira GC, Leão ACA, daRocha WD, Pais FS, Macedo C, Djikeng A, Teixeira SMR, El-Sayed NM. Genomic organization and expression profile of the mucin-associated surface protein (masp) family of the human pathogen Trypanosoma cruzi. Nucleic Acids Res 2009; 37:3407-17. [PMID: 19336417 PMCID: PMC2691823 DOI: 10.1093/nar/gkp172] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
A novel large multigene family was recently identified in the human pathogen Trypanosoma cruzi, causative agent of Chagas disease, and corresponds to ∼6% of the parasite diploid genome. The predicted gene products, mucin-associated surface proteins (MASPs), are characterized by highly conserved N- and C-terminal domains and a strikingly variable and repetitive central region. We report here an analysis of the genomic organization and expression profile of masp genes. Masps are not randomly distributed throughout the genome but instead are clustered with genes encoding mucin and other surface protein families. Masp transcripts vary in size, are preferentially expressed during the trypomastigote stage and contain highly conserved 5′ and 3′ untranslated regions. A sequence analysis of a trypomastigote cDNA library reveals the expression of multiple masp variants with a bias towards a particular masp subgroup. Immunofluorescence assays using antibodies generated against a MASP peptide reveals that the expression of particular MASPs at the cell membrane is limited to subsets of the parasite population. Western blots of phosphatidylinositol-specific phospholipase C (PI-PLC)-treated parasites suggest that MASP may be GPI-anchored and shed into the medium culture, thus contributing to the large repertoire of parasite polypeptides that are exposed to the host immune system.
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Affiliation(s)
- Daniella C Bartholomeu
- Department of Parasitology, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil.
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17
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Gentil LG, Cordero EM, do Carmo MS, dos Santos MRM, da Silveira JF. Posttranscriptional mechanisms involved in the control of expression of the stage-specific GP82 surface glycoprotein in Trypanosoma cruzi. Acta Trop 2009; 109:152-8. [PMID: 19013421 DOI: 10.1016/j.actatropica.2008.10.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2008] [Revised: 09/29/2008] [Accepted: 10/14/2008] [Indexed: 01/08/2023]
Abstract
Trypanosoma cruzi metacyclic trypomastigotes express the developmentally regulated GP82 glycoprotein, which is implicated in host cell invasion. Although GP82 mRNA and protein are not present and the mRNAs barely detectable in epimastigotes, nuclear run-on analysis showed that it is transcribed in both stages. This result indicates that accumulation of transcripts in metacyclic forms is not due to increased transcription of the GP82 gene. To investigate whether mRNA stability may be responsible for the differences in the steady-state levels of this mRNA, parasites were treated with actinomycin D or cycloheximide. When treated with actinomycin D, the half-lives estimated for GP82 transcripts were about 6h in metacyclic trypomastigotes and 0.5h in epimastigotes. In the presence of cycloheximide, the levels of GP82 mRNA decayed slightly after 8h in metacyclic trypomastigotes, whereas in epimastigotes the levels of this mRNA increased. This effect suggests a stabilizing mechanism acting in metacyclic trypomastigotes and a destabilizing mechanism in epimastigotes which could be mediated by an element present in the 3'-UTR of the transcripts. Consistent with this finding, northern blot analysis showed that GP82 mRNAs were mobilized to polysomes and consequently translated, but only in metacyclic trypomastigotes.
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Affiliation(s)
- Luciana Girotto Gentil
- Department of Microbiology, Immunology and Parasitology, Escola Paulista de Medicina, UNIFESP, Rua Botucatu, São Paulo, Brazil
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18
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Campos PC, Bartholomeu DC, DaRocha WD, Cerqueira GC, Teixeira SMR. Sequences involved in mRNA processing in Trypanosoma cruzi. Int J Parasitol 2008; 38:1383-9. [PMID: 18700146 DOI: 10.1016/j.ijpara.2008.07.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2008] [Revised: 06/27/2008] [Accepted: 07/08/2008] [Indexed: 11/25/2022]
Abstract
Gene expression in Trypanosomatids requires processing of polycistronic transcripts to generate monocistronic mRNAs by cleavage events that are coupled to the addition of a Spliced Leader sequence (SL) at the 5'-end and a poly(A) tail at the 3'-end of each mRNA. Here we investigate the sequence requirements involved in Trypanosoma cruzi mRNA processing by mapping all available expressed sequence tags and cDNAs containing poly(A) tail and/or SL to genomic intergenic regions. Amongst other parameters, we determined that the median lengths of 5' untranslated region (UTR) and 3'UTR sequences are 35 and 264 nucleotides, respectively; and that the median distance between SL addition sites and a polypyrimidine motif is 18 nucleotides, whereas the median distance between poly(A) addition sites and the closest polypyrimidine-rich sequence is 40 nucleotides.
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Affiliation(s)
- Priscila C Campos
- Departamento de Bioquímica e Imunologia, ICB, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
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19
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Hyland KV, Asfaw SH, Olson CL, Daniels MD, Engman DM. Bioluminescent imaging of Trypanosoma cruzi infection. Int J Parasitol 2008; 38:1391-400. [PMID: 18511053 DOI: 10.1016/j.ijpara.2008.04.002] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2008] [Revised: 03/31/2008] [Accepted: 04/03/2008] [Indexed: 11/18/2022]
Abstract
Chagas disease, caused by infection with the protozoan parasite Trypanosoma cruzi, is a major public health problem in Central and South America. The pathogenesis of Chagas disease is complex and the natural course of infection is not completely understood. The recent development of bioluminescence imaging technology has facilitated studies of a number of infectious and non-infectious diseases. We developed luminescent T. cruzi to facilitate similar studies of Chagas disease pathogenesis. Luminescent T. cruzi trypomastigotes and amastigotes were imaged in infections of rat myoblast cultures, which demonstrated a clear correlation of photon emission signal strength to the number of parasites used. This was also observed in mice infected with different numbers of luminescent parasites, where a stringent correlation of photon emission to parasite number was observed early at the site of inoculation, followed by dissemination of parasites to different sites over the course of a 25-day infection. Whole animal imaging from ventral, dorsal and lateral perspectives provided clear evidence of parasite dissemination. The tissue distribution of T. cruzi was further determined by imaging heart, spleen, skeletal muscle, lungs, kidneys, liver and intestines ex vivo. These results illustrate the natural dissemination of T. cruzi during infection and unveil a new tool for studying a number of aspects of Chagas disease, including rapid in vitro screening of potential therapeutical agents, roles of parasite and host factors in the outcome of infection, and analysis of differential tissue tropism in various parasite-host strain combinations.
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Affiliation(s)
- Kenneth V Hyland
- Department of Microbiology - Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
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20
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Jäger AV, Muiá RP, Campetella O. Stage-specific expression of Trypanosoma cruzi trans-sialidase involves highly conserved 3′ untranslated regions. FEMS Microbiol Lett 2008; 283:182-8. [DOI: 10.1111/j.1574-6968.2008.01170.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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21
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Coordinate regulation of a family of promastigote-enriched mRNAs by the 3'UTR PRE element in Leishmania mexicana. Mol Biochem Parasitol 2007; 157:54-64. [PMID: 18023890 DOI: 10.1016/j.molbiopara.2007.10.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2006] [Revised: 09/11/2007] [Accepted: 10/02/2007] [Indexed: 11/24/2022]
Abstract
Post-transcriptional regulation is a key feature controlling gene expression in the protozoan parasite Leishmania. The nine-nucleotide paraflagellar rod regulatory element (PRE) in the 3'UTR of Leishmania mexicana PFR2 is both necessary and sufficient for the observed 10-fold higher level of PFR2 mRNA in promastigotes compared to amastigotes. It is also found in the 3'UTRs of all known PFR genes. A search of the Leishmania major Friedlin genomic database revealed several genes that share this cis element including a homolog of a heterotrimeric kinesin II subunit, and a gene that shares identity to a homolog of a Plasmodium antigen. In this study, we show that genes that harbor the PRE display promastigote-enriched transcript accumulation ranging from 4- to 15-fold. Northern analysis on episomal block substitution constructs revealed that the regulatory element is necessary for the proper steady-state accumulation of mRNA in L. mexicana paraflagellar rod gene 4 (PFR4). Also we show that the PRE plays a major role in the proper steady-state mRNA accumulation of PFR1, but may not account for the full regulatory mechanism acting on this mRNA. Our evidence suggests that the PRE coordinately regulates the mRNA abundance of not only the PFR family of genes, but also in a larger group of genes that have unrelated functions. Although the PRE alone can regulate some mRNAs, it may also act in concert with additional elements to control other RNA transcripts.
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22
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Folgueira C, Requena JM. Pitfalls of the CAT reporter gene for analyzing translational regulation in Leishmania. Parasitol Res 2007; 101:1449-52. [PMID: 17676404 DOI: 10.1007/s00436-007-0640-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2007] [Revised: 04/18/2007] [Accepted: 06/13/2007] [Indexed: 10/23/2022]
Abstract
Heterologous reporter genes are widely used for the characterization of gene expression in many organisms. Particularly, constructs bearing reporter genes have greatly contributed to our understanding of gene regulation in kinetoplastids. In some specific circumstances, however, such heterologous reporter has a risk of resulting in irrelevant observations and conclusions, which are primarily due to the introduction of foreign sequence elements. This communication describes our recent experience using the chloramphenicol acetyltransferase (CAT) gene as a reporter for analysis of the translational regulation of HSP70 genes in Leishmania infantum. We show that chimeric mRNAs consisting of the CAT open reading frame (ORF) and the untranslated regions (UTRs) from HSP70-II genes behave differently as endogenous HSP70-II mRNAs and that this difference is due to the presence of CAT sequences. Thus, the main purpose of this communication is to alert researchers working in gene regulation to be cautious when interpreting results based on heterologous reporter genes.
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Affiliation(s)
- Cristina Folgueira
- Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid, 28049, Madrid, Spain
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23
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Brandão A. The untranslated regions of genes from Trypanosoma cruzi: perspectives for functional characterization of strains and isolates. Mem Inst Oswaldo Cruz 2007; 101:775-7. [PMID: 17160286 DOI: 10.1590/s0074-02762006000700011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2006] [Accepted: 08/15/2006] [Indexed: 11/21/2022] Open
Abstract
The sequencing of Trypanosoma cruzi genome has been completed and a great deal of information is now available. However, the organization of protozoa genomes is somewhat elusive and much effort must be applied to reveal all the information coded in the nucleotide sequences. Among the DNA segments that needs further investigation are the untranslated regions of genes. Many of the T. cruzi genes that were revealed by the genome sequencing lack information about the untranslated regions. In this paper, some features of these untranslated segments as well as their applications in T. cruzi populations are discussed.
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Affiliation(s)
- Adeilton Brandão
- Departamento de Medicina Tropical, Instituto Oswaldo Cruz-Fiocruz, 21045-900 Rio de Janeiro, RJ, Brazil.
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24
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Jackson AP, Vaughan S, Gull K. Evolution of tubulin gene arrays in Trypanosomatid parasites: genomic restructuring in Leishmania. BMC Genomics 2006; 7:261. [PMID: 17044946 PMCID: PMC1621084 DOI: 10.1186/1471-2164-7-261] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2006] [Accepted: 10/18/2006] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND alpha- and beta-tubulin are fundamental components of the eukaryotic cytoskeleton and cell division machinery. While overall tubulin expression is carefully controlled, most eukaryotes express multiple tubulin genes in specific regulatory or developmental contexts. The genomes of the human parasites Trypanosoma brucei and Leishmania major reveal that these unicellular kinetoplastids possess arrays of tandem-duplicated tubulin genes, but with differences in organisation. While L. major possesses monotypic alpha and beta arrays in trans, an array of alternating alpha- and beta tubulin genes occurs in T. brucei. Polycistronic transcription in these organisms makes the chromosomal arrangement of tubulin genes important with respect to gene expression. RESULTS We investigated the genomic architecture of tubulin tandem arrays among these parasites, establishing which character state is derived, and the timing of character transition. Tubulin loci in T. brucei and L. major were compared to examine the relationship between the two character states. Intergenic regions between tubulin genes were sequenced from several trypanosomatids and related, non-parasitic bodonids to identify the ancestral state. Evidence of alternating arrays was found among non-parasitic kinetoplastids and all Trypanosoma spp.; monotypic arrays were confirmed in all Leishmania spp. and close relatives. CONCLUSION Alternating and monotypic tubulin arrays were found to be mutually exclusive through comparison of genome sequences. The presence of alternating gene arrays in non-parasitic kinetoplastids confirmed that separate, monotypic arrays are the derived state and evolved through genomic restructuring in the lineage leading to Leishmania. This fundamental reorganisation accounted for the dissimilar genomic architectures of T. brucei and L. major tubulin repertoires.
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Affiliation(s)
- Andrew P Jackson
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire, CB10 1SA, UK
| | - Sue Vaughan
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK
| | - Keith Gull
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK
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25
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da Silva RA, Bartholomeu DC, Teixeira SMR. Control mechanisms of tubulin gene expression in Trypanosoma cruzi. Int J Parasitol 2006; 36:87-96. [PMID: 16233898 DOI: 10.1016/j.ijpara.2005.09.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2005] [Revised: 08/29/2005] [Accepted: 09/13/2005] [Indexed: 11/19/2022]
Abstract
alpha- and beta-Tubulin mRNAs are three to six-fold more abundant in the epimastigote forms than in trypomastigote and amastigote forms of Trypanosoma cruzi. It has been previously shown that the increased abundance of alpha- and beta-tubulin mRNAs found in epimastigotes is due to an increase in their half-lives. By analysing soluble and cytoskeletal protein fractions of the parasite, we found an inverse correlation between tubulin mRNA and the protein levels of free alpha- and beta-tubulin subunits, which are more abundant in trypomastigotes and amastigotes than in epimastigotes. Here we investigated a possible autoregulatory mechanism responsible for the differential accumulation of tubulin mRNAs in T. cruzi by treating epimastigotes with vinblastine and taxol, drugs that disrupt microtubule dynamics by different mechanisms: vinblastine causes significant depolymerisation of tubulin whereas taxol stabilises microtubules. Vinblastine treatment caused significant morphological alterations in epimastigotes whereas taxol does not alter the parasite morphology. Vinblastine, but not taxol, had a specific effect on the levels of alpha- and beta-tubulin mRNAs, causing a five to nine-fold reduction in the steady-state levels of both mRNA populations, whereas the levels of other mRNAs such as gapdh remained unchanged. The reduction in RNA levels caused by vinblastine treatment is mediated by changes in tubulin mRNA half-lives. In an attempt to identify regulatory elements within tubulin mRNAs, plasmids containing luciferase reporter gene associated with 5'-untranslated (UTR), 3'-UTR and part of coding sequence of the tubulin genes were constructed and used for transient DNA transfections of epimastigotes. Determination of luciferase activity in transfected parasites cultured in the presence and absence of vinblastine indicated that sequences located within the alpha-tubulin 3'-UTR and coding region may be involved in modulating the stability of these transcripts in response to changes in the dynamics of T. cruzi microtubules.
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Affiliation(s)
- Rosiane A da Silva
- Departamento de Bioquímica e Imunologia, ICB, Universidade Federal de Minas Gerais, Belo Horizonte, MG 31270-010, Brazil
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26
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Hankins EG, Gillespie JR, Aikenhead K, Buckner FS. Upregulation of sterol C14-demethylase expression in Trypanosoma cruzi treated with sterol biosynthesis inhibitors. Mol Biochem Parasitol 2005; 144:68-75. [PMID: 16165233 DOI: 10.1016/j.molbiopara.2005.08.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2005] [Revised: 08/01/2005] [Accepted: 08/03/2005] [Indexed: 11/26/2022]
Abstract
Infection with the protozoan, Trypanosoma cruzi, is the cause of Chagas disease that occurs widely throughout Latin America. T. cruzi contains sterol biosynthesis enzymes, and produces sterol products similar to those found in fungi. Antifungal drugs that inhibit ergosterol biosynthesis have potent anti-T. cruzi activity in vitro and in animal models. In this report, we describe the effects of sterol biosynthesis inhibitors (simvistatin, zaragosic acid, terbinafine, a lanosterol synthase inhibitor, ketoconazole, and tridemorph) on the regulation of two sterol biosynthesis genes and their protein products. Culturing T. cruzi in the presence of the lanosterol synthase inhibitor, terbinafine, or ketoconazole increased mRNA levels of the sterol C14-demethylase gene approximately 7-12-fold. The sterol C14-demethylase protein levels were also elevated. The effects of the sterol biosynthesis inhibitors on hydroxymethylglutaryl-CoA reductase expression were minimal. Control of the upregulation of sterol C14-demethylase appears to be mediated through the 3'-untranslated region of the gene. The findings demonstrate that T. cruzi can specifically regulate gene expression in response to derangements in its cellular functions.
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Affiliation(s)
- Eleanor G Hankins
- Department of Medicine, University of Washington, Seattle, WA 98195, USA
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27
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Folgueira C, Quijada L, Soto M, Abanades DR, Alonso C, Requena JM. The translational efficiencies of the two Leishmania infantum HSP70 mRNAs, differing in their 3'-untranslated regions, are affected by shifts in the temperature of growth through different mechanisms. J Biol Chem 2005; 280:35172-83. [PMID: 16105831 DOI: 10.1074/jbc.m505559200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Exposure of Leishmania promastigotes to the temperature of their mammalian hosts induces a typical heat-shock response. In Leishmania infantum, HSP70 is encoded by two types of genes that differ in their 3'-untranslated regions (3'-UTRs). Previously, we have shown that specific transcripts for each gene are present in promastigotes growing at normal temperature (26 degrees C), but only transcripts with 3'-UTR-type I (3'-UTRI) accumulate in a temperature-dependent manner. Here, we have investigated the translational efficiencies of both types of HSP70 transcripts at the different temperatures that the parasite encounters in the insect (26 degrees C, normal temperature) or in the mammalian host (heat-shock temperatures). Interestingly, 3'-UTRI-bearing transcripts (HSP70-I) were found associated with ribosomes in promastigotes at normal and heat-shock temperatures, whereas the HSP70-II transcripts appear to be preferentially translated at heat-shock temperatures but not at 26 degrees C. We have analyzed the function of these UTRs in the translational control by use of plasmid constructs in which the CAT reporter gene was flanked by UTRs of the HSP70 genes. Unexpectedly, it was found that CAT transcripts with 3'-UTRII bind to ribosomes at 26 degrees C, and, indeed, the CAT protein is synthesized. A valid conclusion of these experiments was that both types of 3'-UTRs are essential for translation of HSP70 mRNAs at heat shock temperatures, although the 3'-UTRII is more efficient during severe heat shock (39 degrees C). In addition, these results suggest that sequence region other than the 3'-UTR of HSP70-II gene is involved in the translational silent state of HSP70-II transcripts at 26 degrees C. Finally, a null mutant has been created by targeted disruption of both HSP70-II alleles. Remarkably, the deltaHSP70 mutant synthesizes HSP70 at a lower rate than the wild-type parasites. Overall, our data suggest that the biological function of the HSP70-II gene is to top up HSP70 levels under conditions of stress.
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Affiliation(s)
- Cristina Folgueira
- Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid, 28049 Madrid, Spain
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28
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Purdy JE, Donelson JE, Wilson ME. Regulation of genes encoding the major surface protease of Leishmania chagasi via mRNA stability. Mol Biochem Parasitol 2005; 142:88-97. [PMID: 15876463 DOI: 10.1016/j.molbiopara.2005.03.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2004] [Revised: 03/16/2005] [Accepted: 03/23/2005] [Indexed: 01/08/2023]
Abstract
The intercoding regions between many Leishmania sp. genes regulate their mRNA expression. The MSPL mRNA, encoding a subclass of the major surface protease (MSP) of Leishmania chagasi, increases in abundance, when protein synthesis is arrested, while alpha-tubulin (alpha-TUB) mRNA and most other mRNAs do not. We found that the intercoding region between MSPL-coding regions, when cloned downstream of the beta-galactosidase reporter gene (beta-GAL), caused beta-GAL mRNA to increase 8- to 10-fold after inhibiting protein synthesis with cycloheximide. Stable L. chagasi transfectants containing hybrid MSPL/alpha-TUB intercoding regions cloned downstream of beta-GAL were made. The alpha-TUB intercoding region induced high-level baseline beta-GAL mRNA that increased only 1.3-fold after incubation with cycloheximide. In contrast, the MSPL intercoding region, as well as constructs containing nucleotides 303-505 from the MSPL 3'UTR, caused steady-state beta-GAL mRNA levels in the absence of cycloheximide that were approximately 10% of alpha-TUB constructs. These levels increased between 4.4- and 13.2-fold after cycloheximide was added. Constructs containing half of this region (303-394 or 395-505) produced intermediate levels of beta-GAL mRNA and intermediate levels of cycloheximide induction. The kinetics of cycloheximide induction of beta-GAL mRNA was similar with region 303-505 constructs as with constructs bearing the entire endogenous MSPL intercoding region. Furthermore, region 303-505 increased reporter mRNA abundance after cycloheximide by increasing mRNA half-life. Hence, we have identified a 202-nucleotide region within the MSPL 3'UTR that is in part responsible for cycloheximide induction. We hypothesize that this region may interact with labile regulatory protein factor(s).
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Affiliation(s)
- Jay E Purdy
- Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, USA.
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Mishra KK, Holzer TR, Moore LL, LeBowitz JH. A negative regulatory element controls mRNA abundance of the Leishmania mexicana Paraflagellar rod gene PFR2. EUKARYOTIC CELL 2004; 2:1009-17. [PMID: 14555483 PMCID: PMC219351 DOI: 10.1128/ec.2.5.1009-1017.2003] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The Leishmania mexicana PFR2 locus encodes a component of the paraflagellar rod (PFR), a flagellar structure found only in the insect stage of the life cycle. PFR2 mRNA levels are 10-fold lower in the mammalian stage than in the insect stage. Nuclear run-on experiments indicate that the change in PFR2 mRNA abundance is achieved posttranscriptionally. Deletion and block substitution analysis of the entire 1,400-nucleotide 3' untranslated region (UTR) of PFR2C led to the identification of a regulatory element contained within 10 nucleotides of the 3' UTR, termed the PFR regulatory element (PRE), that is necessary for the 10-fold regulation of PFR2 mRNA levels. Comparison of the half-lives of PFR2 transcripts, identical except for the presence or absence of the PRE, revealed that the PRE acts by destabilizing the PFR2 mRNA in amastigotes. The PRE was inserted into a construct which directs the constitutive expression of a chimeric PFR2 transcript. Insertion of the PRE resulted in regulated expression of this transcript, demonstrating that the regulatory element is sufficient for promastigote-specific expression. Since the PRE is present in the 3' UTR of all L. mexicana PFR genes examined so far, we propose that it serves a means of coordinating expression of PFR genes.
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Affiliation(s)
- Krishna K Mishra
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907-2063, USA
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O'Connor RM, Kim K, Khan F, Ward HD. Expression of Cpgp40/15 in Toxoplasma gondii: a surrogate system for the study of Cryptosporidium glycoprotein antigens. Infect Immun 2003; 71:6027-34. [PMID: 14500524 PMCID: PMC201096 DOI: 10.1128/iai.71.10.6027-6034.2003] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cryptosporidium parvum is a waterborne enteric coccidian that causes diarrheal disease in a wide range of hosts. Development of successful therapies is hampered by the inability to culture the parasite and the lack of a transfection system for genetic manipulation. The glycoprotein products of the Cpgp40/15 gene, gp40 and gp15, are involved in C. parvum sporozoite attachment to and invasion of host cells and, as such, may be good targets for anticryptosporidial therapies. However, the function of these antigens appears to be dependent on the presence of multiple O-linked alpha-N-acetylgalactosamine (alpha-GalNAc) determinants. A eukaryotic expression system that would produce proteins bearing glycosylation patterns similar to those found on the native C. parvum glycoproteins would greatly facilitate the molecular and functional characterization of these antigens. As a unique approach to this problem, the Cpgp40/15 gene was transiently expressed in Toxoplasma gondii, and the expressed recombinant glycoproteins were characterized. Antisera to gp40 and gp15 reacted with the surface membranes of tachyzoites expressing the Cpgp40/15 construct, and this reactivity colocalized with that of antiserum to the T. gondii surface protein SAG1. Surface membrane localization was dependent on the presence of the glycophosphatidylinositol anchor attachment site present in the gp15 coding sequence. The presence of terminal O-linked alpha-GalNAc determinants on the T. gondii recombinant gp40 was confirmed by reactivity with Helix pomatia lectin and the monoclonal antibody 4E9, which recognizes alpha-GalNAc residues, and digestion with alpha-N-acetylgalactosaminidase. In addition to appropriate localization and glycosylation, T. gondii apparently processes the gp40/15 precursor into the gp40 and gp15 component glycopolypeptides, albeit inefficiently. These results suggest that a surrogate system using T. gondii for the study of Cryptosporidium biology may be useful.
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Affiliation(s)
- R M O'Connor
- Division of Geographic Medicine and Infectious Diseases, Tufts-New England Medical Center, 50 Washington Street, Boston, MA 02111, USA.
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D'Orso I, Frasch ACC. TcUBP-1, an mRNA destabilizing factor from trypanosomes, homodimerizes and interacts with novel AU-rich element- and Poly(A)-binding proteins forming a ribonucleoprotein complex. J Biol Chem 2002; 277:50520-8. [PMID: 12403777 DOI: 10.1074/jbc.m209092200] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Trypanosomes, protozoan parasites causing worldwide infections in human and animals, mostly regulate protein expression through post-transcriptional mechanisms and not at the transcription initiation level. We have previously identified a Trypanosoma cruzi RNA-binding protein named TcUBP-1. This protein is involved in mRNA destabilization in vivo through binding to AU-rich elements in the 3'-untranslated region of SMUG mucin mRNAs (D'Orso, I., and Frasch, A. C. (2001) J. Biol. Chem. 276, 34801-34809). In this work we show that TcUBP-1 is part of an approximately 450-kDa ribonucleoprotein complex with a poly(A)-binding protein and a novel 18-kDa RNA-binding protein, named TcUBP-2. Recombinant TcUBP-1 and TcUBP-2 proteins recognize U-rich RNAs with similar specificity and affinity through the approximately 92-amino acid RNA recognition motif. TcUBPs can homo- and heterodimerize in vitro through the glycine-rich C-terminal region. This interaction was also detected in vivo by co-immunoprecipitation of the ribonucleoprotein complex and using yeast two-hybrid assay. The poly(A)-binding protein identified was shown to disrupt the formation of TcUBP-1, but not TcUBP-2, homodimers in vitro. The possible role of TcUBP-1 ligands in the pathways that govern mRNA-stability and stage-specific expression in trypanosomes is discussed.
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Affiliation(s)
- Ivan D'Orso
- Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús, CONICET-UNSAM, 1650 San Martin, Provincia de Buenos Aires, Argentina
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Bartholomeu DC, Silva RA, Galvão LMC, el-Sayed NMA, Donelson JE, Teixeira SMR. Trypanosoma cruzi: RNA structure and post-transcriptional control of tubulin gene expression. Exp Parasitol 2002; 102:123-33. [PMID: 12856307 DOI: 10.1016/s0014-4894(03)00034-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Changes in tubulin expression are among the biochemical and morphological adaptations that occur during the life cycle of Trypanosomatids. To investigate the mechanism responsible for the differential accumulation of tubulin mRNAs in Trypanosoma cruzi, we determine the sequences of alpha- and beta-tubulin transcripts and analyzed their expression during the life cycle of the parasite. Two beta-tubulin mRNAs of 1.9 and 2.3 kb were found to differ mainly by an additional 369 nucleotides at the end of the 3' untranslated region (UTR). Although their transcription rates are similar in epimastigotes and amastigotes, alpha- and beta-tubulin transcripts are 3- to 6-fold more abundant in epimastigotes than in trypomastigotes and amastigotes. Accordingly, the half-lives of alpha- and beta-tubulin mRNAs are significantly higher in epimastigotes than in amastigotes. Transient transfection experiments indicated that positive regulatory elements occur in the 3' UTR plus downstream intergenic region of the alpha-tubulin gene and that both positive and negative elements occur in the equivalent regions of the beta-tubulin gene.
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MESH Headings
- Animals
- Base Sequence
- Blotting, Northern
- DNA, Complementary/chemistry
- DNA, Complementary/isolation & purification
- DNA, Protozoan/chemistry
- DNA, Protozoan/isolation & purification
- Gene Expression Regulation/physiology
- Half-Life
- Life Cycle Stages
- Molecular Sequence Data
- RNA Processing, Post-Transcriptional/physiology
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Protozoan/genetics
- RNA, Protozoan/metabolism
- Transcription, Genetic
- Transfection
- Trypanosoma cruzi/genetics
- Trypanosoma cruzi/growth & development
- Tubulin/biosynthesis
- Tubulin/chemistry
- Tubulin/genetics
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Affiliation(s)
- Daniella C Bartholomeu
- Departamento de Bioquímica e Imunologia, ICB, da Universidade Federal de Minas Gerais, Belo Horizonte, MG 31270-010, Brazil
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O'Connor RM, Thorpe CM, Cevallos AM, Ward HD. Expression of the highly polymorphic Cryptosporidium parvum Cpgp40/15 gene in genotype I and II isolates. Mol Biochem Parasitol 2002; 119:203-15. [PMID: 11814572 DOI: 10.1016/s0166-6851(01)00416-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The enteric protozoan Cryptosporidium parvum infects intestinal epithelial cells in a wide range of hosts, causing severe gastrointestinal disease. The invasive sporozoite stage most likely attaches to and invades host cells through multiple host receptor/parasite ligand interactions. Preliminary evidence suggests that the glycoprotein products of the Cpgp40/15 gene, gp40 and gp15, are involved in these interactions. In addition, the Cpgp40/15 gene that encodes these glycopeptides is highly polymorphic in genotype I isolates, suggesting that the gene products may be subject to immune selection. In this study, we characterized the Cpgp40/15 gene in a genotype I isolate and compared expression of the Cpgp40/15 gene in isolates of both genotype. Cpgp40/15 is a single copy gene in both TU502 (genotype I) and GCH1 (genotype II) isolates. However, Northern blot analysis revealed the presence of two transcripts, 2.3 and 1.5 kb in size, in mRNA from GCH1 as well as TU502-infected Caco-2A cells. Accumulation of the two Cpgp40/15 mRNAs peaked 12-24 h post-infection. Using 3'RACE analysis, three polyadenylation sites were identified 371, 978 and 1002 bp downstream of the GCH1 Cpgp40/15 stop codon. Two of these polyadenylation sites were also used in TU502. The sequences of the GCH1 Cpgp40/15 3'untranslated regions (3'UTRs) were identical to genomic sequence and shared 96.7% homology with TU502 3'UTRs. Actinomycin D treatment of GCH1-infected Caco-2A cells followed by Northern blot analysis, revealed that the stability of the 1.5 kb message was considerably greater than that of the 2.3 kb transcript.
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Affiliation(s)
- Roberta M O'Connor
- Division of Geographic Medicine and Infectious Diseases, New England Medical Center, Tufts University School of Medicine, Box 041, 750 Washington Street, Boston, MA 02111, USA.
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D'Orso I, Frasch AC. TcUBP-1, a developmentally regulated U-rich RNA-binding protein involved in selective mRNA destabilization in trypanosomes. J Biol Chem 2001; 276:34801-9. [PMID: 11435421 DOI: 10.1074/jbc.m102120200] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Developmental stages of the trypanosome life cycle differ in their morphology, biology, and biochemical properties. Consequently, several proteins have to be tightly regulated in their expression to allow trypanosomes to adapt rapidly to sudden environmental changes, a process that might be of central importance for parasite survival. However, in contrast to higher eukaryotic cells, trypanosomes do not seem to regulate gene expression through regulation of transcription initiation. These parasites make use of post-transcriptional regulatory mechanisms and modification of mRNA half-life is a relevant one. Trans-acting factors binding to cis-elements that affect mRNA stability of mature transcripts have not been identified in these cells. In this work, a novel U-rich RNA-binding protein (TcUBP-1) from Trypanosoma cruzi, the agent of Chagas disease, was identified. Its structure includes an RNA recognition motif, a nuclear export signal, and auxiliary domains with glycine- and glutamine-rich regions. TcUBP-1 recognizes the 44-nucleotide AU-rich RNA instability element located in the 3'-untranslated region of mucin SMUG mRNAs (Di Noia, J. M., D'Orso, I., Sanchez, D. O., and Frasch, A. C. (2000) J. Biol. Chem. 275, 10218-10227) as well as GU-rich sequences. Over-expression of TcUBP-1 in trypanosomes decreases the half-life of SMUG mucin mRNAs in vivo but does not affect the stability of other parasite mRNAs. Because TcUBP-1 is developmentally regulated, it might have a relevant role in regulating protein expression during trypanosome differentiation, allowing a correct expression pattern of U-rich-containing mRNAs.
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Affiliation(s)
- I D'Orso
- Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús, Consejo Nacional de Investigaciones Cientificas y Técnicas, Universidad Nacional de General San Martin, 1650 San Martin, Provincia de Buenos Aires, Argentina
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Frasch AC. Functional diversity in the trans-sialidase and mucin families in Trypanosoma cruzi. PARASITOLOGY TODAY (PERSONAL ED.) 2000; 16:282-6. [PMID: 10858646 DOI: 10.1016/s0169-4758(00)01698-7] [Citation(s) in RCA: 231] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Trypanosomes are unable to synthesize the monosaccharide sialic acid, but some African trypanosomes and the American Trypanosoma cruzi can incorporate sialic acid derived from the host. To do so, T. cruzi expresses a trans-sialidase, an enzyme that catalyzes the transfer of sialic acid from host glycoconjugates to mucin-like molecules located on the parasite surface membrane. The importance of the process is indicated by the fact that T. cruzi has hundreds of genes encoding trans-sialidase, trans-sialidase-like proteins and mucin core proteins. Sequence divergence of members of these families has resulted in some molecules having functions unrelated to the acquisition of sialic acid. In this article, Alberto Frasch reviews the structure and possible function of the proteins making up these families.
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Affiliation(s)
- A C Frasch
- Instituto de Investigaciones Biotecnologicas, Universidad Nacional de General San Martin, CC30, San Martin, Buenos Aires, Argentina.
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Bates EJ, Knuepfer E, Smith DF. Poly(A)-binding protein I of Leishmania: functional analysis and localisation in trypanosomatid parasites. Nucleic Acids Res 2000; 28:1211-20. [PMID: 10666465 PMCID: PMC102622 DOI: 10.1093/nar/28.5.1211] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Regulation of gene expression in trypanosomatid parasites is predominantly post-transcriptional. Primary transcripts are trans-spliced and polyadenylated to generate mature mRNAs and transcript stability is a major factor controlling stage-specific gene expression. Degenerate PCR has been used to clone the gene encoding the Leishmania homologue of poly(A)-binding protein (Lm PAB1), as an approach to the identification of trans-acting factors involved in this atypical mode of eukaryotic gene expression. lmpab1 is a single copy gene encoding a 63 kDa protein which shares major structural features but only 35-40% amino acid identity with other PAB1 sequences, including those of other trypanosomatids. Lm PAB1 is expressed at constant levels during parasite differentiation and is phosphorylated in vivo. It is localised predominantly in the cytoplasm but inhibition of transcription with actinomycin D also reveals diffuse localisation in the nucleus. Lm PAB1 binds poly(A) with high specificity and affinity but fails to complement a null mutation in Saccharomyces cerevisiae. These properties are indicative of functional divergence in vivo.
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Affiliation(s)
- E J Bates
- Wellcome Laboratories for Molecular Parasitology, Department of Biochemistry, Imperial College of Science, Technology and Medicine, London SW7 2AZ, UK
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