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Siau A, Ang JW, Sheriff O, Hoo R, Loh HP, Tay D, Huang X, Yam XY, Lai SK, Meng W, Julca I, Kwan SS, Mutwil M, Preiser PR. Comparative spatial proteomics of Plasmodium-infected erythrocytes. Cell Rep 2023; 42:113419. [PMID: 37952150 DOI: 10.1016/j.celrep.2023.113419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 07/14/2023] [Accepted: 10/25/2023] [Indexed: 11/14/2023] Open
Abstract
Plasmodium parasites contribute to one of the highest global infectious disease burdens. To achieve this success, the parasite has evolved a range of specialized subcellular compartments to extensively remodel the host cell for its survival. The information to fully understand these compartments is likely hidden in the so far poorly characterized Plasmodium species spatial proteome. To address this question, we determined the steady-state subcellular location of more than 12,000 parasite proteins across five different species by extensive subcellular fractionation of erythrocytes infected by Plasmodium falciparum, Plasmodium knowlesi, Plasmodium yoelii, Plasmodium berghei, and Plasmodium chabaudi. This comparison of the pan-species spatial proteomes and their expression patterns indicates increasing species-specific proteins associated with the more external compartments, supporting host adaptations and post-transcriptional regulation. The spatial proteome offers comprehensive insight into the different human, simian, and rodent Plasmodium species, establishing a powerful resource for understanding species-specific host adaptation processes in the parasite.
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Affiliation(s)
- Anthony Siau
- Nanyang Technological University, School of Biological Sciences, Singapore 637551, Singapore
| | - Jing Wen Ang
- Nanyang Technological University, School of Biological Sciences, Singapore 637551, Singapore
| | - Omar Sheriff
- Nanyang Technological University, School of Biological Sciences, Singapore 637551, Singapore
| | - Regina Hoo
- Nanyang Technological University, School of Biological Sciences, Singapore 637551, Singapore
| | - Han Ping Loh
- Nanyang Technological University, School of Biological Sciences, Singapore 637551, Singapore
| | - Donald Tay
- Nanyang Technological University, School of Biological Sciences, Singapore 637551, Singapore
| | - Ximei Huang
- Nanyang Technological University, School of Biological Sciences, Singapore 637551, Singapore
| | - Xue Yan Yam
- Nanyang Technological University, School of Biological Sciences, Singapore 637551, Singapore
| | - Soak Kuan Lai
- Nanyang Technological University, School of Biological Sciences, Singapore 637551, Singapore
| | - Wei Meng
- Nanyang Technological University, School of Biological Sciences, Singapore 637551, Singapore
| | - Irene Julca
- Nanyang Technological University, School of Biological Sciences, Singapore 637551, Singapore
| | - Sze Siu Kwan
- Nanyang Technological University, School of Biological Sciences, Singapore 637551, Singapore
| | - Marek Mutwil
- Nanyang Technological University, School of Biological Sciences, Singapore 637551, Singapore
| | - Peter R Preiser
- Nanyang Technological University, School of Biological Sciences, Singapore 637551, Singapore.
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Olatunde AC, Cornwall DH, Roedel M, Lamb TJ. Mouse Models for Unravelling Immunology of Blood Stage Malaria. Vaccines (Basel) 2022; 10:1525. [PMID: 36146602 PMCID: PMC9501382 DOI: 10.3390/vaccines10091525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2022] [Revised: 09/05/2022] [Accepted: 09/06/2022] [Indexed: 11/16/2022] Open
Abstract
Malaria comprises a spectrum of disease syndromes and the immune system is a major participant in malarial disease. This is particularly true in relation to the immune responses elicited against blood stages of Plasmodium-parasites that are responsible for the pathogenesis of infection. Mouse models of malaria are commonly used to dissect the immune mechanisms underlying disease. While no single mouse model of Plasmodium infection completely recapitulates all the features of malaria in humans, collectively the existing models are invaluable for defining the events that lead to the immunopathogenesis of malaria. Here we review the different mouse models of Plasmodium infection that are available, and highlight some of the main contributions these models have made with regards to identifying immune mechanisms of parasite control and the immunopathogenesis of malaria.
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Affiliation(s)
| | | | | | - Tracey J. Lamb
- Department of Pathology, University of Utah, Emma Eccles Jones Medical Research Building, 15 N Medical Drive E, Room 1420A, Salt Lake City, UT 84112, USA
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Ruiz JL, Gómez-Díaz E. The second life of Plasmodium in the mosquito host: gene regulation on the move. Brief Funct Genomics 2020; 18:313-357. [PMID: 31058281 DOI: 10.1093/bfgp/elz007] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 03/08/2019] [Accepted: 03/26/2019] [Indexed: 01/08/2023] Open
Abstract
Malaria parasites face dynamically changing environments and strong selective constraints within human and mosquito hosts. To survive such hostile and shifting conditions, Plasmodium switches transcriptional programs during development and has evolved mechanisms to adjust its phenotype through heterogeneous patterns of gene expression. In vitro studies on culture-adapted isolates have served to set the link between chromatin structure and functional gene expression. Yet, experimental evidence is limited to certain stages of the parasite in the vertebrate, i.e. blood, while the precise mechanisms underlying the dynamic regulatory landscapes during development and in the adaptation to within-host conditions remain poorly understood. In this review, we discuss available data on transcriptional and epigenetic regulation in Plasmodium mosquito stages in the context of sporogonic development and phenotypic variation, including both bet-hedging and environmentally triggered direct transcriptional responses. With this, we advocate the mosquito offers an in vivo biological model to investigate the regulatory networks, transcription factors and chromatin-modifying enzymes and their modes of interaction with regulatory sequences, which might be responsible for the plasticity of the Plasmodium genome that dictates stage- and cell type-specific blueprints of gene expression.
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Affiliation(s)
- José L Ruiz
- Instituto de Parasitología y Biomedicina López-Neyra (IPBLN), Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Elena Gómez-Díaz
- Instituto de Parasitología y Biomedicina López-Neyra (IPBLN), Consejo Superior de Investigaciones Científicas, Granada, Spain
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4
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Brashear AM, Roobsoong W, Siddiqui FA, Nguitragool W, Sattabongkot J, López-Uribe MM, Miao J, Cui L. A glance of the blood stage transcriptome of a Southeast Asian Plasmodium ovale isolate. PLoS Negl Trop Dis 2019; 13:e0007850. [PMID: 31730621 PMCID: PMC6881071 DOI: 10.1371/journal.pntd.0007850] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 11/27/2019] [Accepted: 10/16/2019] [Indexed: 11/24/2022] Open
Abstract
Plasmodium ovale accounts for a disproportionate number of travel-related malaria cases. This parasite is understudied since there is a reliance on clinical samples. We collected a P. ovale curtisi parasite isolate from a clinical case in western Thailand and performed RNA-seq analysis on the blood stage transcriptomes. Using both de novo assembly and alignment-based methods, we detected the transcripts for 6628 out of 7280 annotated genes. For those lacking evidence of expression, the vast majority belonged to the PIR and STP1 gene families. We identified new splicing patterns for over 2500 genes, and mapped at least one untranslated region for over half of all annotated genes. Our analysis also detected a notable presence of anti-sense transcripts for over 10% of P. ovale curtisi genes. This transcriptomic analysis provides new insights into the blood-stage biology of this neglected parasite.
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Affiliation(s)
- Awtum M. Brashear
- Department of Entomology, Pennsylvania State University, Department of Entomology, University Park, Pennsylvania, United States of America
- Department of Internal Medicine, University of South Florida, Tampa, Florida, United States of America
| | - Wanlapa Roobsoong
- Mahidol Vivax Research Unit, Faculty of Tropical Medicine, Mahidol University, Thailand
| | - Faiza A. Siddiqui
- Department of Internal Medicine, University of South Florida, Tampa, Florida, United States of America
| | - Wang Nguitragool
- Department of Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University, Thailand
| | - Jetsumon Sattabongkot
- Mahidol Vivax Research Unit, Faculty of Tropical Medicine, Mahidol University, Thailand
| | - Margarita M. López-Uribe
- Department of Entomology, Pennsylvania State University, Department of Entomology, University Park, Pennsylvania, United States of America
| | - Jun Miao
- Department of Internal Medicine, University of South Florida, Tampa, Florida, United States of America
| | - Liwang Cui
- Department of Entomology, Pennsylvania State University, Department of Entomology, University Park, Pennsylvania, United States of America
- Department of Internal Medicine, University of South Florida, Tampa, Florida, United States of America
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5
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Abstract
Alternative splicing is a widespread, essential, and complex component of gene regulation. Apicomplexan parasites have long been recognized to produce alternatively spliced transcripts for some genes and can produce multiple protein products that are essential for parasite growth. Alternative splicing is a widespread, essential, and complex component of gene regulation. Apicomplexan parasites have long been recognized to produce alternatively spliced transcripts for some genes and can produce multiple protein products that are essential for parasite growth. Recent approaches are now providing more wide-ranging surveys of the extent of alternative splicing; some indicate that alternative splicing is less widespread than in other model eukaryotes, whereas others suggest levels comparable to those of previously studied groups. In many cases, apicomplexan alternative splicing events appear not to generate multiple alternative proteins but instead produce aberrant or noncoding transcripts. Nonetheless, appropriate regulation of alternative splicing is clearly essential in Plasmodium and Toxoplasma parasites, suggesting a biological role for at least some of the alternative splicing observed. Several studies have now disrupted conserved regulators of alternative splicing and demonstrated lethal effects in apicomplexans. This minireview discusses methods to accurately determine the extent of alternative splicing in Apicomplexa and discuss potential biological roles for this conserved process in a phylum of parasites with compact genomes.
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Plasmodium genomics: an approach for learning about and ending human malaria. Parasitol Res 2018; 118:1-27. [PMID: 30402656 DOI: 10.1007/s00436-018-6127-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 10/19/2018] [Indexed: 12/31/2022]
Abstract
Malaria causes high levels of morbidity and mortality in human beings worldwide. According to the World Health Organization (WHO), about half a million people die of this disease each year. Malaria is caused by six species of parasites belonging to the Plasmodium genus: P. falciparum, P. knowlesi, P. vivax, P. malariae, P. ovale curtisi, and P. ovale wallikeri. Currently, malaria is being kept under control with varying levels of elimination success in different countries. The development of new molecular tools as well as the use of next-generation sequencing (NGS) technologies and novel bioinformatic approaches has improved our knowledge of malarial epidemiology, diagnosis, treatment, vaccine development, and surveillance strategies. In this work, the genetics and genomics of human malarias have been analyzed. Since the first P. falciparum genome was sequenced in 2002, various population-level genetic and genomic surveys, together with transcriptomic and proteomic studies, have shown the importance of molecular approaches in supporting malaria elimination.
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7
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Eshar S, Altenhofen L, Rabner A, Ross P, Fastman Y, Mandel-Gutfreund Y, Karni R, Llinás M, Dzikowski R. PfSR1 controls alternative splicing and steady-state RNA levels in Plasmodium falciparum through preferential recognition of specific RNA motifs. Mol Microbiol 2015; 96:1283-97. [PMID: 25807998 DOI: 10.1111/mmi.13007] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/23/2015] [Indexed: 11/28/2022]
Abstract
Plasmodium species have evolved complex biology to adapt to different hosts and changing environments throughout their life cycle. Remarkably, these adaptations are achieved by a relatively small genome. One way by which the parasite expands its proteome is through alternative splicing (AS). We recently identified PfSR1 as a bona fide Ser/Arg-rich (SR) protein that shuttles between the nucleus and cytoplasm and regulates AS in Plasmodium falciparum. Here we show that PfSR1 is localized adjacent to the Nuclear Pore Complex (NPC) clusters in the nucleus of early stage parasites. To identify the endogenous RNA targets of PfSR1, we adapted an inducible overexpression system for tagged PfSR1 and performed RNA immunoprecipitation followed by microarray analysis (RIP-chip) to recover and identify the endogenous RNA targets that bind PfSR1. Bioinformatic analysis of these RNAs revealed common sequence motifs potentially recognized by PfSR1. RNA-EMSAs show that PfSR1 preferentially binds RNA molecules containing these motifs. Interestingly, we find that PfSR1 not only regulates AS but also the steady-state levels of mRNAs containing these motifs in vivo.
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Affiliation(s)
- Shiri Eshar
- Department of Microbiology and Molecular Genetics, The Kuvin Center for the Study of Infectious and Tropical Diseases, The Institute for Medical Research Israel-Canada, The Hebrew University - Hadassah Medical School, Jerusalem, Israel
| | - Lindsey Altenhofen
- Department of Molecular Biology and Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, 08544, USA.,Department of Biochemistry and Molecular Biology, Department of Chemistry and Center for Malaria Research, Pennsylvania State University, State College, PA, 16802, USA
| | - Alona Rabner
- Department of Biology, Israel Institute of Technology-Technion, Haifa, Israel
| | - Phil Ross
- Department of Biochemistry and Molecular Biology, Department of Chemistry and Center for Malaria Research, Pennsylvania State University, State College, PA, 16802, USA
| | - Yair Fastman
- Department of Microbiology and Molecular Genetics, The Kuvin Center for the Study of Infectious and Tropical Diseases, The Institute for Medical Research Israel-Canada, The Hebrew University - Hadassah Medical School, Jerusalem, Israel
| | | | - Rotem Karni
- Department of Biochemistry and Molecular Biology, The Institute for Medical Research Israel-Canada, The Hebrew University - Hadassah Medical School, Jerusalem, Israel
| | - Manuel Llinás
- Department of Molecular Biology and Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, 08544, USA.,Department of Biochemistry and Molecular Biology, Department of Chemistry and Center for Malaria Research, Pennsylvania State University, State College, PA, 16802, USA
| | - Ron Dzikowski
- Department of Microbiology and Molecular Genetics, The Kuvin Center for the Study of Infectious and Tropical Diseases, The Institute for Medical Research Israel-Canada, The Hebrew University - Hadassah Medical School, Jerusalem, Israel
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8
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Yeoh LM, Goodman CD, Hall NE, van Dooren GG, McFadden GI, Ralph SA. A serine-arginine-rich (SR) splicing factor modulates alternative splicing of over a thousand genes in Toxoplasma gondii. Nucleic Acids Res 2015; 43:4661-75. [PMID: 25870410 PMCID: PMC4482073 DOI: 10.1093/nar/gkv311] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2014] [Accepted: 03/27/2015] [Indexed: 11/12/2022] Open
Abstract
Single genes are often subject to alternative splicing, which generates alternative mature mRNAs. This phenomenon is widespread in animals, and observed in over 90% of human genes. Recent data suggest it may also be common in Apicomplexa. These parasites have small genomes, and economy of DNA is evolutionarily favoured in this phylum. We investigated the mechanism of alternative splicing in Toxoplasma gondii, and have identified and localized TgSR3, a homologue of ASF/SF2 (alternative-splicing factor/splicing factor 2, a serine-arginine–rich, or SR protein) to a subnuclear compartment. In addition, we conditionally overexpressed this protein, which was deleterious to growth. qRT-PCR was used to confirm perturbation of splicing in a known alternatively-spliced gene. We performed high-throughput RNA-seq to determine the extent of splicing modulated by this protein. Current RNA-seq algorithms are poorly suited to compact parasite genomes, and hence we complemented existing tools by writing a new program, GeneGuillotine, that addresses this deficiency by segregating overlapping reads into distinct genes. In order to identify the extent of alternative splicing, we released another program, JunctionJuror, that detects changes in intron junctions. Using this program, we identified about 2000 genes that were constitutively alternatively spliced in T. gondii. Overexpressing the splice regulator TgSR3 perturbed alternative splicing in over 1000 genes.
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Affiliation(s)
- Lee M Yeoh
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria 3010, Australia School of BioSciences, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Christopher D Goodman
- School of BioSciences, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Nathan E Hall
- Department of Genetics, La Trobe Institute for Molecular Science, La Trobe University, Bundoora, Victoria 3086, Australia Life Sciences Computation Centre, Victorian Life Sciences Computation Initiative, Carlton, Victoria 3010, Australia
| | - Giel G van Dooren
- Research School of Biology, The Australian National University, Acton, ACT 2601, Australia
| | - Geoffrey I McFadden
- School of BioSciences, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Stuart A Ralph
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria 3010, Australia
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9
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The N-terminal segment of Plasmodium falciparum SURFIN4.1 is required for its trafficking to the red blood cell cytosol through the endoplasmic reticulum. Parasitol Int 2013; 62:215-29. [DOI: 10.1016/j.parint.2012.12.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Revised: 12/18/2012] [Accepted: 12/20/2012] [Indexed: 11/24/2022]
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10
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Eshar S, Allemand E, Sebag A, Glaser F, Muchardt C, Mandel-Gutfreund Y, Karni R, Dzikowski R. A novel Plasmodium falciparum SR protein is an alternative splicing factor required for the parasites' proliferation in human erythrocytes. Nucleic Acids Res 2012; 40:9903-16. [PMID: 22885299 PMCID: PMC3479193 DOI: 10.1093/nar/gks735] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Malaria parasites have a complex life cycle, during which they undergo significant biological changes to adapt to different hosts and changing environments. Plasmodium falciparum, the species responsible for the deadliest form of human malaria, maintains this complex life cycle with a relatively small number of genes. Alternative splicing (AS) is an important post-transcriptional mechanisms that enables eukaryotic organisms to expand their protein repertoire out of relatively small number of genes. SR proteins are major regulators of AS in higher eukaryotes. Nevertheless, the regulation of splicing as well as the AS machinery in Plasmodium spp. are still elusive. Here, we show that PfSR1, a putative P. falciparum SR protein, can mediate RNA splicing in vitro. In addition, we show that PfSR1 functions as an AS factor in mini-gene in vivo systems similar to the mammalian SR protein SRSF1. Expression of PfSR1-myc in P. falciparum shows distinct patterns of cellular localization during intra erythrocytic development. Furthermore, we determine that the predicted RS domain of PfSR1 is essential for its localization to the nucleus. Finally, we demonstrate that proper regulation of pfsr1 is required for parasite proliferation in human RBCs and over-expression of pfsr1 influences AS activity of P. falciparum genes in vivo.
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Affiliation(s)
- Shiri Eshar
- Department of Microbiology and Molecular Genetics, The Kuvin Center for Study of Infectious and Tropical Diseases, IMRIC, The Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel
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11
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Cernetich-Ott A, Daly TM, Vaidya AB, Bergman LW, Burns JM. Remarkable stability in patterns of blood-stage gene expression during episodes of non-lethal Plasmodium yoelii malaria. Malar J 2012; 11:265. [PMID: 22866913 PMCID: PMC3489522 DOI: 10.1186/1475-2875-11-265] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Accepted: 07/22/2012] [Indexed: 11/12/2022] Open
Abstract
Background Microarray studies using in vitro cultures of synchronized, blood-stage Plasmodium falciparum malaria parasites have revealed a ‘just-in-time’ cascade of gene expression with some indication that these transcriptional patterns remain stable even in the presence of external stressors. However, direct analysis of transcription in P. falciparum blood-stage parasites obtained from the blood of infected patients suggests that parasite gene expression may be modulated by factors present in the in vivo environment of the host. The aim of this study was to examine changes in gene expression of the rodent malaria parasite, Plasmodium yoelii 17X, while varying the in vivo setting of replication. Methods Using P. yoelii 17X parasites replicating in vivo, differential gene expression in parasites isolated from individual mice, from independent infections, during ascending, peak and descending parasitaemia and in the presence and absence of host antibody responses was examined using P. yoelii DNA microarrays. A genome-wide analysis to identify coordinated changes in groups of genes associated with specific biological pathways was a primary focus, although an analysis of the expression patterns of two multi-gene families in P. yoelii, the yir and pyst-a families, was also completed. Results Across experimental conditions, transcription was surprisingly stable with little evidence for distinct transcriptional states or for consistent changes in specific pathways. Differential gene expression was greatest when comparing differences due to parasite load and/or host cell availability. However, the number of differentially expressed genes was generally low. Of genes that were differentially expressed, many involved biologically diverse pathways. There was little to no differential expression of members of the yir and pyst-a multigene families that encode polymorphic proteins associated with the membrane of infected erythrocytes. However, a relatively large number of these genes were expressed during blood-stage infection regardless of experimental condition. Conclusions Taken together, these results indicate that 1) P. yoelii gene expression remains stable in the presence of a changing host environment, and 2) concurrent expression of a large number of the polymorphic yir and pyst-a genes, rather than differential expression in response to specific host factors, may in itself limit the effectiveness of host immune responses.
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Affiliation(s)
- Amy Cernetich-Ott
- Centre for Molecular Parasitology, Department of Microbiology and Immunology, Drexel University College of Medicine, 2900 Queen Lane, Philadelphia, PA 19129, USA
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Lawton J, Brugat T, Yan YX, Reid AJ, Böhme U, Otto TD, Pain A, Jackson A, Berriman M, Cunningham D, Preiser P, Langhorne J. Characterization and gene expression analysis of the cir multi-gene family of Plasmodium chabaudi chabaudi (AS). BMC Genomics 2012; 13:125. [PMID: 22458863 PMCID: PMC3384456 DOI: 10.1186/1471-2164-13-125] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Accepted: 03/29/2012] [Indexed: 11/13/2022] Open
Abstract
Background The pir genes comprise the largest multi-gene family in Plasmodium, with members found in P. vivax, P. knowlesi and the rodent malaria species. Despite comprising up to 5% of the genome, little is known about the functions of the proteins encoded by pir genes. P. chabaudi causes chronic infection in mice, which may be due to antigenic variation. In this model, pir genes are called cirs and may be involved in this mechanism, allowing evasion of host immune responses. In order to fully understand the role(s) of CIR proteins during P. chabaudi infection, a detailed characterization of the cir gene family was required. Results The cir repertoire was annotated and a detailed bioinformatic characterization of the encoded CIR proteins was performed. Two major sub-families were identified, which have been named A and B. Members of each sub-family displayed different amino acid motifs, and were thus predicted to have undergone functional divergence. In addition, the expression of the entire cir repertoire was analyzed via RNA sequencing and microarray. Up to 40% of the cir gene repertoire was expressed in the parasite population during infection, and dominant cir transcripts could be identified. In addition, some differences were observed in the pattern of expression between the cir subgroups at the peak of P. chabaudi infection. Finally, specific cir genes were expressed at different time points during asexual blood stages. Conclusions In conclusion, the large number of cir genes and their expression throughout the intraerythrocytic cycle of development indicates that CIR proteins are likely to be important for parasite survival. In particular, the detection of dominant cir transcripts at the peak of P. chabaudi infection supports the idea that CIR proteins are expressed, and could perform important functions in the biology of this parasite. Further application of the methodologies described here may allow the elucidation of CIR sub-family A and B protein functions, including their contribution to antigenic variation and immune evasion.
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Affiliation(s)
- Jennifer Lawton
- Division of Parasitology, MRC National Institute for Medical Research, London, UK
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Ebbinghaus P, Krücken J. Characterization and tissue-specific expression patterns of the Plasmodium chabaudi cir multigene family. Malar J 2011; 10:272. [PMID: 21929749 PMCID: PMC3189184 DOI: 10.1186/1475-2875-10-272] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2011] [Accepted: 09/19/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Variant antigens expressed on the surface of parasitized red blood cells (pRBCs) are important virulence factors of malaria parasites. Whereas Plasmodium falciparum erythrocyte membrane proteins 1 (PfEMP1) are responsible for sequestration of mature parasites, little is known about putative ligands mediating cytoadherence to host receptors in other Plasmodium species. Candidates include members of the pir superfamily found in the human parasite Plasmodium vivax (vir), in the simian pathogen Plasmodium knowlesi (kir) and in the rodent malarias Plasmodium yoelii (yir), Plasmodium berghei (bir) and Plasmodium chabaudi (cir). The aim of this study was to reveal a potential involvement of cir genes in P. chabaudi sequestration. METHODS Subfamilies of cir genes were identified by bioinformatic analyses of annotated sequence data in the Plasmodium Genome Database. In order to examine tissue-specific differences in the expression of cir mRNAs, RT-PCR with subfamily-specific primers was used. In total, 432 cDNA clones derived from six different tissues were sequenced to characterize the transcribed cir gene repertoire. To confirm differences in transcription profiles of cir genes, restriction fragment length polymorphism (RFLP) analyses were performed to compare different host tissues and to identify changes during the course of P. chabaudi infections in immunocompetent mice. RESULTS The phylogenetic analysis of annotated P. chabaudi putative CIR proteins identified two major subfamilies. Comparison of transcribed cir genes from six different tissues revealed significant differences in the frequency clones belonging to individual cir gene subgroups were obtained from different tissues. Further hints of difference in the transcription of cir genes in individual tissues were obtained by RFLP. Whereas only minimal changes in the transcription pattern of cir genes could be detected during the developmental cycle of the parasites, switching to expression of other cir genes during the course of an infection was observed around or after peak parasitemia. CONCLUSIONS The tissue-specific expression of cir mRNAs found in this study indicates correlation between expression of CIR antigens and distribution of parasites in inner organs. Together with comparable results for other members of the pir superfamily this suggests a role of cir and other pir genes in antigenic variation and sequestration of malaria parasites.
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Affiliation(s)
- Petra Ebbinghaus
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Königsweg 67, 14163 Berlin, Germany
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14
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Jemmely NY, Niang M, Preiser PR. Small variant surface antigens and Plasmodium evasion of immunity. Future Microbiol 2010; 5:663-82. [PMID: 20353305 DOI: 10.2217/fmb.10.21] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Antigenic variation at the Plasmodium-infected erythrocyte surface plays a critical role in malaria disease severity and host immune evasion. Our current understanding of the role of Plasmodium variant surface antigens in antigenic variation and immune evasion is largely limited to the extensive work carried out on the Plasmodium falciparum var gene family. Although homologues of var genes are not present in other malaria species, small variant gene families comprising the rif and stevor genes in P. falciparum and the pir genes in Plasmodium vivax, Plasmodium knowlesi and the rodent malaria Plasmodium chabaudi, Plasmodium berghei and Plasmodium yoelii also show features suggesting a role in antigenic variation and immune evasion. In this article, we highlight our current understanding of these variant antigens and provide insights on the mechanisms developed by malaria parasites to effectively avoid the host immune response and establish chronic infection.
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Affiliation(s)
- Noelle Yvonne Jemmely
- Nanyang Technological University, School of Biological Sciences, 60 Nanyang Drive, Singapore 637551, Singapore.
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Diez D, Hayes N, Joannin N, Normark J, Kanehisa M, Wahlgren M, Wheelock CE, Goto S. varDB: a database of antigenic variant sequences--current status and future prospects. Acta Trop 2010; 114:144-51. [PMID: 19539588 DOI: 10.1016/j.actatropica.2009.06.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2009] [Revised: 06/03/2009] [Accepted: 06/09/2009] [Indexed: 11/19/2022]
Abstract
Antigenic variation is a common mechanism employed by many pathogenic organisms to avoid recognition of surface proteins by the host immune system. The malaria parasite, Plasmodium falciparum, among many others, exploits this mechanism and manages to survive in an otherwise hostile environment. Although similarities in the mechanisms used among different species to generate antigenic variation are broadly recognized, there is a lack of studies using cross-species data. The varDB project (http://www.vardb.org) was created to study antigenic variation at a range of different levels, both within and among species. The project aims to serve as a resource to increase our understanding of antigenic variation by providing a framework for comparative studies. In this review we describe the varDB project, its construction, and the overall organization of information with the intent of increasing the utility of varDB to the research community. The current version of varDB supports 27 species involved in 19 different diseases affecting humans as well as other species. These data include 42 gene families that are represented by over 67,000 sequences. The varDB project is still in its infancy but is expected to continue to grow with the addition of new organisms and gene families as well as input from the general research community.
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Affiliation(s)
- Diego Diez
- Bioinformatics Center, Institute for Chemical Research, Kyoto University, Uji, Kyoto, Japan
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Cunningham D, Lawton J, Jarra W, Preiser P, Langhorne J. The pir multigene family of Plasmodium: antigenic variation and beyond. Mol Biochem Parasitol 2010; 170:65-73. [PMID: 20045030 DOI: 10.1016/j.molbiopara.2009.12.010] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2009] [Revised: 12/18/2009] [Accepted: 12/22/2009] [Indexed: 11/15/2022]
Abstract
Multigene families are present on the telomeric and sub-telomeric regions of most chromosomes of the malaria parasite, Plasmodium. The largest gene family identified so far is the Plasmodium interspersed repeat (pir) multigene gene family and is shared by Plasmodium vivax, and simian and rodent malaria species. Most pir genes share a similar structure across the different species; a short first exon, long second exon and a third exon encoding a trans-membrane domain, and some pir genes can be assigned to specific sub-families. Although pir genes can be differentially transcribed in different life cycle stages, suggesting different functions, there is no clear link between sub-family and transcription pattern. Some of the pir genes encode proteins expressed on or near the surface of infected erythrocytes, and therefore could be potential targets of the host's immune response, and involved in antigenic variation and immune evasion. Other functions such as signalling, trafficking and adhesion have been also postulated. The presence of pir in rodent models will allow the investigation of this gene family in vivo and thus their potential as vaccines or in other interventions in human P. vivax infections.
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Affiliation(s)
- Deirdre Cunningham
- Division of Parasitology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, United Kingdom
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Redefining the expressed prototype SICAvar gene involved in Plasmodium knowlesi antigenic variation. Malar J 2009; 8:181. [PMID: 19646264 PMCID: PMC3152765 DOI: 10.1186/1475-2875-8-181] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2009] [Accepted: 07/31/2009] [Indexed: 11/14/2022] Open
Abstract
Background The SICAvar gene family, expressed at the surface of infected erythrocytes, is critical for antigenic variation in Plasmodium knowlesi. When this family was discovered, a prototypic SICAvar gene was characterized and defined by a 10-exon structure. The predicted 205-kDa protein lacked a convincing signal peptide, but included a series of variable cysteine-rich modules, a transmembrane domain encoded by the penultimate exon, and a cytoplasmic domain encoded by the final highly conserved exon. The 205 SICAvar gene and its family with up to 108 possible family members, was identified prior to the sequencing of the P. knowlesi genome. However, in the published P. knowlesi database this gene remains disjointed in five fragments. This study addresses a number of structural and functional questions that are critical for understanding SICAvar gene expression. Methods Database mining, bioinformatics, and traditional genomic and post-genomic experimental methods including proteomic technologies are used here to confirm the genomic context and expressed structure of the prototype 205 SICAvar gene. Results This study reveals that the 205 SICAvar gene reported previously to have a 10-exon expressed gene structure has, in fact, 12 exons, with an unusually large and repeat-laden intron separating two newly defined upstream exons and the bona fide 5'UTR from the remainder of the gene sequence. The initial exon encodes a PEXEL motif, which may function to localize the SICA protein in the infected erythrocyte membrane. This newly defined start of the 205 SICAvar sequence is positioned on chromosome 5, over 340 kb upstream from the rest of the telomerically positioned SICAvar gene sequence in the published genome assembly. This study, however, verifies the continuity of these sequences, a 9.5 kb transcript, and provides evidence that the 205 SICAvar gene is located centrally on chromosome 5. Conclusion The prototype 205 SICAvar gene has been redefined to have a 12-exon structure. These data are important because they 1) address questions raised in the P. knowlesi genome database regarding SICAvar gene fragments, numbers and structures, 2) show that this prototype gene encodes a PEXEL motif, 3) emphasize the need for further refinement of the P. knowlesi genome data, and 4) retrospectively, provide evidence for recombination within centrally located SICAvar sequences.
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Cunningham D, Fonager J, Jarra W, Carret C, Preiser P, Langhorne J. Rapid changes in transcription profiles of the Plasmodium yoelii yir multigene family in clonal populations: lack of epigenetic memory? PLoS One 2009; 4:e4285. [PMID: 19173007 PMCID: PMC2628738 DOI: 10.1371/journal.pone.0004285] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2008] [Accepted: 12/04/2008] [Indexed: 11/18/2022] Open
Abstract
The pir multigene family, found in the genomes of Plasmodium vivax, P. knowlesi and the rodent malaria species, encode variant antigens that could be targets of the immune response. Individual parasites of the rodent malaria Plasmodium yoelii, selected by micromanipulation, transcribe only 1 to 3 different pir (yir) suggesting tight transcriptional control at the level of individual cells. Using microarray and quantitative RT-PCR, we show that despite this very restricted transcription in a single cell, many yir genes are transcribed throughout the intra-erythrocytic asexual cycle. The timing and level of transcription differs between genes, with some being more highly transcribed in ring and trophozoite stages, whereas others are more highly transcribed in schizonts. Infection of immunodeficient mice with single infected erythrocytes results in populations of parasites each with transcriptional profiles different from that of the parent parasite population and from each other. This drift away from the original 'set' of transcribed genes does not appear to follow a preset pattern and "epigenetic memory" of the yir transcribed in the parent parasite can be rapidly lost. Thus, regulation of pir gene transcription may be different from that of the well-characterised multigene family, var, of Plasmodium falciparum.
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Affiliation(s)
- Deirdre Cunningham
- Division of Parasitology, National Institute for Medical Research, London, United Kingdom
| | - Jannik Fonager
- Division of Parasitology, National Institute for Medical Research, London, United Kingdom
| | - William Jarra
- Division of Parasitology, National Institute for Medical Research, London, United Kingdom
| | - Celine Carret
- Pathogen Microarrays Group, The Wellcome Trust Sanger Institute, Cambridge, United Kingdom
| | - Peter Preiser
- Bioscience Research Centre, Nanyang Technical University, Singapore
| | - Jean Langhorne
- Division of Parasitology, National Institute for Medical Research, London, United Kingdom
- * E-mail:
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Fernandez-Becerra C, Yamamoto MM, Vêncio RZN, Lacerda M, Rosanas-Urgell A, del Portillo HA. Plasmodium vivax and the importance of the subtelomeric multigene vir superfamily. Trends Parasitol 2008; 25:44-51. [PMID: 19036639 DOI: 10.1016/j.pt.2008.09.012] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2007] [Revised: 06/02/2008] [Accepted: 09/30/2008] [Indexed: 11/25/2022]
Abstract
Plasmodium vivax is responsible for more than 100 million clinical cases yearly. Unlike P. falciparum, in which infected red blood cells cytoadhere via variant proteins, avoiding passage through the spleen, P.-vivax-infected reticulocytes seem not to cytoadhere. However, a variant subtelomeric multigene vir family has been identified in P. vivax. Thus, questions remain about how P. vivax circulates through the spleen and the role of Vir proteins. In this review, the importance of the vir multigene superfamily is reviewed in the light of the completion of the entire genome sequence of P. vivax and from data gathered from experimental infections in reticulocyte-prone non-lethal malaria parasites and natural P. vivax infections.
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Affiliation(s)
- Carmen Fernandez-Becerra
- Barcelona Centre for International Health Research, Hospital Clinic/IDIBAPS, Universitat de Barcelona, Rosello 132, 08036 Barcelona, Spain
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Distinct malaria parasite sporozoites reveal transcriptional changes that cause differential tissue infection competence in the mosquito vector and mammalian host. Mol Cell Biol 2008; 28:6196-207. [PMID: 18710954 DOI: 10.1128/mcb.00553-08] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The malaria parasite sporozoite transmission stage develops and differentiates within parasite oocysts on the Anopheles mosquito midgut. Successful inoculation of the parasite into a mammalian host is critically dependent on the sporozoite's ability to first infect the mosquito salivary glands. Remarkable changes in tissue infection competence are observed as the sporozoites transit from the midgut oocysts to the salivary glands. Our microarray analysis shows that compared to oocyst sporozoites, salivary gland sporozoites upregulate expression of at least 124 unique genes. Conversely, oocyst sporozoites show upregulation of at least 47 genes (upregulated in oocyst sporozoites [UOS genes]) before they infect the salivary glands. Targeted gene deletion of UOS3, encoding a putative transmembrane protein with a thrombospondin repeat that localizes to the sporozoite secretory organelles, rendered oocyst sporozoites unable to infect the mosquito salivary glands but maintained the parasites' liver infection competence. This phenotype demonstrates the significance of differential UOS expression. Thus, the UIS-UOS gene classification provides a framework to elucidate the infectivity and transmission success of Plasmodium sporozoites on a whole-genome scale. Genes identified herein might represent targets for vector-based transmission blocking strategies (UOS genes), as well as strategies that prevent mammalian host infection (UIS genes).
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Joannin N, Abhiman S, Sonnhammer EL, Wahlgren M. Sub-grouping and sub-functionalization of the RIFIN multi-copy protein family. BMC Genomics 2008; 9:19. [PMID: 18197962 PMCID: PMC2257938 DOI: 10.1186/1471-2164-9-19] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2007] [Accepted: 01/15/2008] [Indexed: 01/06/2023] Open
Abstract
Background Parasitic protozoans possess many multicopy gene families which have central roles in parasite survival and virulence. The number and variability of members of these gene families often make it difficult to predict possible functions of the encoded proteins. The families of extra-cellular proteins that are exposed to a host immune response have been driven via immune selection to become antigenically variant, and thereby avoid immune recognition while maintaining protein function to establish a chronic infection. Results We have combined phylogenetic and function shift analyses to study the evolution of the RIFIN proteins, which are antigenically variant and are encoded by the largest multicopy gene family in Plasmodium falciparum. We show that this family can be subdivided into two major groups that we named A- and B-RIFIN proteins. This suggested sub-grouping is supported by a recently published study that showed that, despite the presence of the Plasmodium export (PEXEL) motif in all RIFIN variants, proteins from each group have different cellular localizations during the intraerythrocytic life cycle of the parasite. In the present study we show that function shift analysis, a novel technique to predict functional divergence between sub-groups of a protein family, indicates that RIFINs have undergone neo- or sub-functionalization. Conclusion These results question the general trend of clustering large antigenically variant protein groups into homogenous families. Assigning functions to protein families requires their subdivision into meaningful groups such as we have shown for the RIFIN protein family. Using phylogenetic and function shift analysis methods, we identify new directions for the investigation of this broad and complex group of proteins.
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Affiliation(s)
- Nicolas Joannin
- Department of Microbiology, Tumor and Cell biology (MTC), Karolinska Institutet, SE-17177 Stockholm, Sweden and Swedish Institute for Infectious Diseases Control, SE-17182 Stockholm, Sweden.
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