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Cui L, Lindner S, Miao J. Translational regulation during stage transitions in malaria parasites. Ann N Y Acad Sci 2014; 1342:1-9. [PMID: 25387887 DOI: 10.1111/nyas.12573] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The complicated life cycle of the malaria parasite involves a vertebrate host and a mosquito vector, and translational regulation plays a prominent role in orchestrating the developmental events in the two transition stages: gametocytes and sporozoites. Translational regulation is executed in both global and transcript-specific manners. Plasmodium uses a conserved mechanism involving phosphorylation of eIF2α to repress global protein synthesis during the latent period of sporozoite development in the mosquito salivary glands. Transcript-specific translational regulation is achieved by a network of RNA-binding proteins (RBPs), among which the Dhh1 RNA helicase DOZI and Puf family RBPs are by far the best studied in Plasmodium. While the DOZI complex defines a new P granule with a role in protecting certain gametocyte mRNAs from degradation, the Puf proteins appear to repress expression of mRNAs in both gametocytes and sporozoites. These examples underscore the significance of translational regulation in Plasmodium development.
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Coleman BI, Skillman KM, Jiang RHY, Childs LM, Altenhofen LM, Ganter M, Leung Y, Goldowitz I, Kafsack BF, Marti M, Llinás M, Buckee CO, Duraisingh MT. A Plasmodium falciparum histone deacetylase regulates antigenic variation and gametocyte conversion. Cell Host Microbe 2014; 16:177-186. [PMID: 25121747 PMCID: PMC4188636 DOI: 10.1016/j.chom.2014.06.014] [Citation(s) in RCA: 156] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2014] [Revised: 05/06/2014] [Accepted: 06/06/2014] [Indexed: 01/20/2023]
Abstract
The asexual forms of the malaria parasite Plasmodium falciparum are adapted for chronic persistence in human red blood cells, continuously evading host immunity using epigenetically regulated antigenic variation of virulence-associated genes. Parasite survival on a population level also requires differentiation into sexual forms, an obligatory step for further human transmission. We reveal that the essential nuclear gene, P. falciparum histone deacetylase 2 (PfHda2), is a global silencer of virulence gene expression and controls the frequency of switching from the asexual cycle to sexual development. PfHda2 depletion leads to dysregulated expression of both virulence-associated var genes and PfAP2-g, a transcription factor controlling sexual conversion, and is accompanied by increases in gametocytogenesis. Mathematical modeling further indicates that PfHda2 has likely evolved to optimize the parasite's infectious period by achieving low frequencies of virulence gene expression switching and sexual conversion. This common regulation of cellular transcriptional programs mechanistically links parasite transmissibility and virulence.
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Affiliation(s)
- Bradley I. Coleman
- Department of Immunology & Infectious Diseases Harvard School of Public Health, Boston, MA 02115 USA
| | - Kristen M. Skillman
- Department of Immunology & Infectious Diseases Harvard School of Public Health, Boston, MA 02115 USA
| | - Rays H. Y. Jiang
- Department of Immunology & Infectious Diseases Harvard School of Public Health, Boston, MA 02115 USA
| | - Lauren M. Childs
- Department of Epidemiology and Center for Communicable Disease Dynamics, Harvard School of Public Health, Boston MA 02115 USA
| | - Lindsey M. Altenhofen
- Department of Molecular Biology and Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton NJ 08544 USA
| | - Markus Ganter
- Department of Immunology & Infectious Diseases Harvard School of Public Health, Boston, MA 02115 USA
| | - Yvette Leung
- Department of Immunology & Infectious Diseases Harvard School of Public Health, Boston, MA 02115 USA
| | - Ilana Goldowitz
- Department of Immunology & Infectious Diseases Harvard School of Public Health, Boston, MA 02115 USA
| | - Björn F.C. Kafsack
- Department of Molecular Biology and Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton NJ 08544 USA
| | - Matthias Marti
- Department of Immunology & Infectious Diseases Harvard School of Public Health, Boston, MA 02115 USA
| | - Manuel Llinás
- Department of Molecular Biology and Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton NJ 08544 USA
| | - Caroline O. Buckee
- Department of Epidemiology and Center for Communicable Disease Dynamics, Harvard School of Public Health, Boston MA 02115 USA
| | - Manoj T. Duraisingh
- Department of Immunology & Infectious Diseases Harvard School of Public Health, Boston, MA 02115 USA
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Liu M, Miao J, Liu T, Sullivan WJ, Cui L, Chen X. Characterization of TgPuf1, a member of the Puf family RNA-binding proteins from Toxoplasma gondii. Parasit Vectors 2014; 7:141. [PMID: 24685055 PMCID: PMC3997814 DOI: 10.1186/1756-3305-7-141] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2014] [Accepted: 03/24/2014] [Indexed: 12/15/2022] Open
Abstract
Background Puf proteins act as translational regulators and affect many cellular processes in a wide range of eukaryotic organisms. Although Puf proteins have been well characterized in many model systems, little is known about the structural and functional characteristics of Puf proteins in the parasite Toxoplasma gondii. Methods Using a combination of conventional molecular approaches, we generated endogenous TgPuf1 tagged with hemagglutinin (HA) epitope and investigated the TgPuf1 expression levels and localization in the tachyzoites and bradyzoites. We used RNA Electrophoretic Mobility Shfit Assay (EMSA) to determine whether the recombination TgPuf1 has conserverd RNA binding activity and specificity. Results TgPuf1 was expressed at a significantly higher level in bradyzoites than in tachyzoites. TgPuf1 protein was predominantly localized within the cytoplasm and showed a much more granular cytoplasmic staining pattern in bradyzoites. The recombinant Puf domain of TgPuf1 showed strong binding affinity to two RNA fragments containing Puf-binding motifs from other organisms as artificial target sequences. However, two point mutations in the core Puf-binding motif resulted in a significant reduction in binding affinity, indicating that TgPuf1 also binds to conserved Puf-binding motif. Conclusions TgPuf1 appears to exhibit different expression levels in the tachyzoites and bradyzoites, suggesting that TgPuf1 may function in regulating the proliferation or/and differentiation that are important in providing parasites with the ability to respond rapidly to changes in environmental conditions. This study provides a starting point for elucidating the function of TgPuf1 during parasite development.
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Affiliation(s)
| | | | | | | | - Liwang Cui
- Department of Pathogen Biology, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, Guangdong 510515, China.
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Vasquez JJ, Hon CC, Vanselow JT, Schlosser A, Siegel TN. Comparative ribosome profiling reveals extensive translational complexity in different Trypanosoma brucei life cycle stages. Nucleic Acids Res 2014; 42:3623-37. [PMID: 24442674 PMCID: PMC3973304 DOI: 10.1093/nar/gkt1386] [Citation(s) in RCA: 126] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
While gene expression is a fundamental and tightly controlled cellular process that is regulated at multiple steps, the exact contribution of each step remains unknown in any organism. The absence of transcription initiation regulation for RNA polymerase II in the protozoan parasite Trypanosoma brucei greatly simplifies the task of elucidating the contribution of translation to global gene expression. Therefore, we have sequenced ribosome-protected mRNA fragments in T. brucei, permitting the genome-wide analysis of RNA translation and translational efficiency. We find that the latter varies greatly between life cycle stages of the parasite and ∼100-fold between genes, thus contributing to gene expression to a similar extent as RNA stability. The ability to map ribosome positions at sub-codon resolution revealed extensive translation from upstream open reading frames located within 5' UTRs and enabled the identification of hundreds of previously un-annotated putative coding sequences (CDSs). Evaluation of existing proteomics and genome-wide RNAi data confirmed the translation of previously un-annotated CDSs and suggested an important role for >200 of those CDSs in parasite survival, especially in the form that is infective to mammals. Overall our data show that translational control plays a prevalent and important role in different parasite life cycle stages of T. brucei.
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Affiliation(s)
- Juan-José Vasquez
- Research Center for Infectious Diseases, University of Wuerzburg, Wuerzburg 97080, Germany, Département Biologie cellulaire et infection, Institut Pasteur, Unité Biologie Cellulaire du Parasitisme, Paris 75015, France, INSERM U786, Paris 75015, France and Rudolf Virchow Center, University of Wuerzburg, Wuerzburg 97080, Germany
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55
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Kramer S. RNA in development: how ribonucleoprotein granules regulate the life cycles of pathogenic protozoa. WILEY INTERDISCIPLINARY REVIEWS-RNA 2013; 5:263-84. [PMID: 24339376 DOI: 10.1002/wrna.1207] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2013] [Revised: 10/22/2013] [Accepted: 10/29/2013] [Indexed: 12/11/2022]
Abstract
Ribonucleoprotein (RNP) granules are important posttranscriptional regulators of messenger RNA (mRNA) fate. Several types of RNP granules specifically regulate gene expression during development of multicellular organisms and are commonly referred to as germ granules. The function of germ granules is not entirely understood and probably diverse, but it is generally agreed that one main function is posttranscriptional regulation of gene expression during early development, when transcription is silent. One example is the translational repression of maternally derived mRNAs in oocytes. Here, I hope to show that the need for regulation of gene expression by RNP granules is not restricted to animal development, but plays an equally important role during the development of pathogenic protozoa. Apicomplexa and Trypanosomatidae have complex life cycles with frequent host changes. The need to quickly adapt gene expression to a new environment as well as the ability to suppress translation to survive latencies is critical for successful completion of life cycles. Posttranscriptional gene regulation is not necessarily simpler in protozoa. Apicomplexa surprise with the presence of micro RNA (miRNAs) and upstream open reading frames (µORFs). Trypanosomes have an unusually large repertoire of different RNP granule types. A better understanding of RNP granules in protozoa may help to gain insight into the evolutionary origin of RNP granules: Trypanosomes for example have two types of granules with interesting similarities to animal germ granules.
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Affiliation(s)
- Susanne Kramer
- Lehrstuhl für Zell- und Entwicklungsbiologie, Biozentrum, Universität Würzburg, Würzburg, Germany
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Abstract
SUMMARYEimeriais a common genus of apicomplexan parasites that infect diverse vertebrates, most notably poultry, causing serious disease and economic loss. Like all apicomplexans, eimerians have a complex life cycle characterized by asexual divisions that amplify the parasite population in preparation for sexual reproduction. This can be divided into three events: gametocytogenesis, producing gametocytes from merozoites; gametogenesis, producing microgametes and macrogametes from gametocytes; and fertilization of macrogametes by microgametes, producing diploid zygotes with ensuing meiosis completing the sexual phase. Sexual development inEimeriadepends on the differential expression of stage-specific genes, rather than presence or absence of sex chromosomes. Thus, it involves the generation of specific structures and, implicitly, storage of proteins and regulation of protein expression in macrogametes, in preparation for fertilization. InEimeria, the formation of a unique, resilient structure, the oocyst wall, is essential for completion of the sexual phase and parasite transmission. In this review, we piece together the molecular events that underpin sexual reproduction inEimeriaand use additional details from analogous events inPlasmodiumto fill current knowledge gaps. The mechanisms governing sexual stage formation and subsequent fertilization may represent targets for counteracting parasite transmission.
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Miao J, Fan Q, Parker D, Li X, Li J, Cui L. Puf mediates translation repression of transmission-blocking vaccine candidates in malaria parasites. PLoS Pathog 2013; 9:e1003268. [PMID: 23637595 PMCID: PMC3630172 DOI: 10.1371/journal.ppat.1003268] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2012] [Accepted: 02/08/2013] [Indexed: 01/01/2023] Open
Abstract
Translational control of gene expression plays an essential role in development. In malaria parasites, translational regulation is critical during the development of specialized transition stages between the vertebrate host and mosquito vector. Here we show that a Pumilio/FBF (Puf) family RNA-binding protein, PfPuf2, is required for the translation repression of a number of transcripts in gametocytes including two genes encoding the transmission-blocking vaccine candidates Pfs25 and Pfs28. Whereas studies to date support a paradigm of Puf-mediated translation regulation through 3' untranslated regions (UTRs) of target mRNAs, this study, for the first time, identifies a functional Puf-binding element (PBE) in the 5'UTR of pfs25. We provide both in vitro and in vivo evidence to demonstrate that PfPuf2 binds to the PBEs in pfs25 and pfs28 to mediate translation repression. This finding provides a renewed view of Pufs as versatile translation regulators and sheds light on their functions in the development of lower branches of eukaryotes.
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Affiliation(s)
- Jun Miao
- Department of Entomology, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Qi Fan
- Department of Entomology, Pennsylvania State University, University Park, Pennsylvania, United States of America
- Dalian Institute of Biotechnology, Dalian, Liaoning Province, China
| | - Daniel Parker
- Department of Entomology, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Xiaolian Li
- Department of Entomology, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Jianyong Li
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Liwang Cui
- Department of Entomology, Pennsylvania State University, University Park, Pennsylvania, United States of America
- * E-mail:
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58
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Transposon mutagenesis identifies genes essential for Plasmodium falciparum gametocytogenesis. Proc Natl Acad Sci U S A 2013; 110:E1676-84. [PMID: 23572579 DOI: 10.1073/pnas.1217712110] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Gametocytes are essential for Plasmodium transmission, but little is known about the mechanisms that lead to their formation. Using piggyBac transposon-mediated insertional mutagenesis, we screened for parasites that no longer form mature gametocytes, which led to the isolation of 29 clones (insertional gametocyte-deficient mutants) that fail to form mature gametocytes. Additional analysis revealed 16 genes putatively responsible for the loss of gametocytogenesis, none of which has been previously implicated in gametocytogenesis. Transcriptional profiling and detection of an early stage gametocyte antigen determined that a subset of these mutants arrests development at stage I or in early stage II gametocytes, likely representing genes involved in gametocyte maturation. The remaining mutants seem to arrest before formation of stage I gametocytes and may represent genes involved in commitment to the gametocyte lineage.
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59
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Lindner SE, Mikolajczak SA, Vaughan AM, Moon W, Joyce BR, Sullivan WJ, Kappe SHI. Perturbations of Plasmodium Puf2 expression and RNA-seq of Puf2-deficient sporozoites reveal a critical role in maintaining RNA homeostasis and parasite transmissibility. Cell Microbiol 2013; 15:1266-83. [PMID: 23356439 DOI: 10.1111/cmi.12116] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Revised: 01/18/2013] [Accepted: 01/22/2013] [Indexed: 12/30/2022]
Abstract
Malaria's cycle of infection requires parasite transmission between a mosquito vector and a mammalian host. We here demonstrate that the Plasmodium yoelii Pumilio-FBF family member Puf2 allows the sporozoite to remain infectious in the mosquito salivary glands while awaiting transmission. Puf2 mediates this solely through its RNA-binding domain (RBD) likely by stabilizing or hastening the degradation of specific mRNAs. Puf2 traffics to sporozoite cytosolic granules, which are negative for several markers of stress granules and P-bodies, and disappear rapidly after infection of hepatocytes. In contrast to previously described Plasmodium berghei pbpuf2(-) parasites, pypuf2(-) sporozoites have no apparent defect in host infection when tested early in salivary gland residence, but become progressively non-infectious and prematurely transform into EEFs during prolonged salivary gland residence. The premature overexpression of Puf2 in oocysts causes striking deregulation of sporozoite maturation and infectivity while extension of Puf2 expression in liverstages causes no defect, suggesting that the presence of Puf2 alone is not sufficient for its functions. Finally, by conducting the first comparative RNA-seq analysis of Plasmodium sporozoites, we find that Puf2 may play a role in directly or indirectly maintaining the homeostasis of specific transcripts. These findings uncover requirements for maintaining a window of opportunity for the malaria parasite to accommodate the unpredictable moment of transmission from mosquito to mammalian host.
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Affiliation(s)
- Scott E Lindner
- Seattle Biomedical Research Institute, Seattle, WA 98109, USA
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60
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Pornthanakasem W, Kongkasuriyachai D, Uthaipibull C, Yuthavong Y, Leartsakulpanich U. Plasmodium serine hydroxymethyltransferase: indispensability and display of distinct localization. Malar J 2012; 11:387. [PMID: 23173711 PMCID: PMC3521198 DOI: 10.1186/1475-2875-11-387] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Accepted: 11/20/2012] [Indexed: 12/21/2022] Open
Abstract
Background Serine hydroxymethyltransferase (SHMT), a pyridoxal phosphate-dependent enzyme, plays a vital role in the de novo pyrimidine biosynthesis pathway in malaria parasites. Two genes have been identified in Plasmodium spp. encoding a cytosolic SHMT (cSHMT) and putative mitochondria SHMT (mSHMT), but their roles have not been fully investigated. Methods The presence of Plasmodium SHMT isoforms in the intra-erythrocytic stage was assessed based on their gene expression using reverse transcription PCR (RT-PCR). Localization studies of Plasmodium SHMT isoforms were performed by transfection of fluorescent-tagged gene constructs into P. falciparum and expressions of fluorescent fusion proteins in parasites were observed using a laser scanning confocal microscope. Genetic targeting through homologous recombination was used to study the essentiality of SHMT in Plasmodium spp. Results Semi-quantitative RT-PCR revealed the expression of these two genes throughout intra-erythrocytic development. Localization studies using P. falciparum expressing fluorescent-tagged SHMT showed that PfcSHMT-red fluorescent fusion protein (PfcSHMT-DsRed) is localized in the cytoplasm, while PfmSHMT-green fluorescent fusion protein (PfmSHMT-GFP) co-localized with Mitotracker™-labelled mitochondria as predicted. The essentiality of plasmodial cSHMT was inferred from transfection experiments where recovery of viable knock-out parasites was not achieved, unless complemented with a functional equivalent copy of shmt. Conclusions Distinct compartment localizations of PfSHMT were observed between cytoplasmic and mitochondrial isoforms, and evidence was provided for the indispensable role of plasmodial cSHMT indicating it as a valid target for development of novel anti-malarials.
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Affiliation(s)
- Wichai Pornthanakasem
- National Center for Genetic Engineering and Biotechnology, 113 Phahonyothin Road, Khlong Nueng, Khlong Luang, Pathum Thani, 12120, Thailand
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Reininger L, Garcia M, Tomlins A, Müller S, Doerig C. The Plasmodium falciparum, Nima-related kinase Pfnek-4: a marker for asexual parasites committed to sexual differentiation. Malar J 2012; 11:250. [PMID: 22849771 PMCID: PMC3495404 DOI: 10.1186/1475-2875-11-250] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Accepted: 07/13/2012] [Indexed: 12/15/2022] Open
Abstract
Background Malaria parasites undergo, in the vertebrate host, a developmental switch from asexual replication to sexual differentiation leading to the formation of gametocytes, the only form able to survive in the mosquito vector. Regulation of the onset of the sexual phase remains largely unknown and represents an important gap in the understanding of the parasite’s complex biology. Methods The expression and function of the Nima-related kinase Pfnek-4 during the early sexual development of the human malaria parasite Plasmodium falciparum were investigated, using three types of transgenic Plasmodium falciparum 3D7 lines: (i) episomally expressing a Pfnek-4-GFP fusion protein under the control of its cognate pfnek-4 promoter; (ii) episomally expressing negative or positive selectable markers, yeast cytosine deaminase-uridyl phosphoribosyl transferase, or human dihydrofolate reductase, under the control of the pfnek-4 promoter; and (iii) lacking a functional pfnek-4 gene. Parasite transfectants were analysed by fluorescence microscopy and flow cytometry. In vitro growth rate and gametocyte formation were determined by Giemsa-stained blood smears. Results The Pfnek-4-GFP protein was found to be expressed in stage II to V gametocytes and, unexpectedly, in a subset of asexual-stage parasites undergoing schizogony. Culture conditions stimulating gametocyte formation resulted in significant increase of this schizont subpopulation. Moreover, sorted asexual parasites expressing the Pfnek-4-GFP protein displayed elevated gametocyte formation when returned to in vitro culture in presence of fresh red blood cells, when compared to GFP- parasites from the same initial population. Negative selection of asexual parasites expressing pfnek-4 showed a marginal reduction in growth rate, whereas positive selection caused a marked reduction in parasitaemia, but was not sufficient to completely abolish proliferation. Pfnek-4- clones are not affected in their asexual growth and produced normal numbers of stage V gametocytes. Conclusions The results indicate that Pfnek-4 is not strictly gametocyte-specific, and is expressed in a small subset of asexual parasites displaying high rate conversion to sexual development. Pfnek-4 is not required for erythrocytic schizogony and gametocytogenesis. This is the first study to report the use of a molecular marker for the sorting of sexually-committed schizont stage P. falciparum parasites, which opens the way to molecular characterization of this pre-differentiated subpopulation.
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Affiliation(s)
- Luc Reininger
- CNRS USR3151, Station Biologique, Place Georges Teissier, 29680, Roscoff, France.
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Liu Z, Miao J, Cui L. Gametocytogenesis in malaria parasite: commitment, development and regulation. Future Microbiol 2012; 6:1351-69. [PMID: 22082293 DOI: 10.2217/fmb.11.108] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Malaria parasites have evolved a complicated life cycle alternating between two hosts. Gametocytes are produced in the vertebrate hosts and are obligatory for natural transmission of the parasites through mosquito vectors. The mechanism of sexual development in Plasmodium has been the focus of extensive studies. In the postgenomic era, the advent of genome-wide analytical tools and genetic manipulation technology has enabled rapid advancement of our knowledge in this area. Patterns of gene expression during sexual development, molecular distinction of the two sexes, and mechanisms underlying subsequent formation of gametes and their fertilization have been progressively elucidated. However, the triggers and mechanism of sexual development remain largely unknown. This article provides an update of our understanding of the molecular and cellular events associated with the decision for commitment to sexual development and regulation of gene expression during gametocytogenesis. Insights into the molecular mechanisms of gametocyte development are essential for designing proper control strategies for interruption of malaria transmission and ultimate elimination.
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Affiliation(s)
- Zhenyu Liu
- Department of Entomology, The Pennsylvania State University, 537 ASI Building University Park, PA 16802, USA
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63
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Lack of association of the S769N mutation in Plasmodium falciparum SERCA (PfATP6) with resistance to artemisinins. Antimicrob Agents Chemother 2012; 56:2546-52. [PMID: 22354307 DOI: 10.1128/aac.05943-11] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The recent emergence of artemisinin (ART) resistance in Plasmodium falciparum in western Cambodia, manifested as delayed parasite clearance, is a big threat to the long-term efficacy of this family of antimalarial drugs. Among the multiple candidate genes associated with ART resistance in P. falciparum, the sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPase PfATP6 has been postulated as a specific target of ARTs. The PfATP6 gene harbors multiple single-nucleotide polymorphisms in field parasite populations, and S769N has been associated with decreased sensitivity to artemether in parasite populations from French Guiana. In this study, we used an allelic exchange strategy to engineer parasite lines carrying the S769N mutations in P. falciparum strain 3D7 and evaluated whether introduction of this mutation modulated parasite sensitivity to ART derivatives. Using three transgenic lines carrying the 769N mutation and two transgenic lines carrying the wild-type 769S as controls, we found that S769N did not affect PfATP6 gene expression. We compared the sensitivities of these parasite lines to three ART derivatives, artemether, artesunate, and dihydroartemisinin, in 18 biological experiments and detected no significant effect of the S769N mutation on parasite response to these ART derivatives. This study provides further evidence for the lack of association of PfATP6 with ART resistance.
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64
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Trout K, Clopton RE. Metronidazole induces gametocytogenesis in gregarine associations maintained in vitro. J Parasitol 2012; 98:666-8. [PMID: 22263562 DOI: 10.1645/ge-3020.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Gametocytogenesis was induced in mature associations of Protomagalhaensia wolfi and Protomagalhaensia blaberae maintained in vitro by inclusion of metronidazole in the culture medium. The response was neither strictly dosage dependent nor uniform across gregarine species. We hypothesize that metronidazole induces gregarine gametocytogenesis by disrupting PUF2 proteins responsible for the translational control of sexual development and gametocytogenesis in apicomplexans.
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Affiliation(s)
- Kate Trout
- Department of Natural Science, Peru State College, Peru, Nebraska 68421, USA
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65
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Affiliation(s)
- David S. Guttery
- Centre for Genetics and Genomics, School of Biology, Queens Medical Centre, University of Nottingham, Nottingham, United Kingdom
| | - Anthony A. Holder
- Division of Parasitology, MRC National Institute for Medical Research, Mill Hill, London, United Kingdom
| | - Rita Tewari
- Centre for Genetics and Genomics, School of Biology, Queens Medical Centre, University of Nottingham, Nottingham, United Kingdom
- * E-mail:
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66
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Gomes-Santos CSS, Braks J, Prudêncio M, Carret C, Gomes AR, Pain A, Feltwell T, Khan S, Waters A, Janse C, Mair GR, Mota MM. Transition of Plasmodium sporozoites into liver stage-like forms is regulated by the RNA binding protein Pumilio. PLoS Pathog 2011; 7:e1002046. [PMID: 21625527 PMCID: PMC3098293 DOI: 10.1371/journal.ppat.1002046] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2010] [Accepted: 03/22/2011] [Indexed: 12/13/2022] Open
Abstract
Many eukaryotic developmental and cell fate decisions that are effected post-transcriptionally involve RNA binding proteins as regulators of translation of key mRNAs. In malaria parasites (Plasmodium spp.), the development of round, non-motile and replicating exo-erythrocytic liver stage forms from slender, motile and cell-cycle arrested sporozoites is believed to depend on environmental changes experienced during the transmission of the parasite from the mosquito vector to the vertebrate host. Here we identify a Plasmodium member of the RNA binding protein family PUF as a key regulator of this transformation. In the absence of Pumilio-2 (Puf2) sporozoites initiate EEF development inside mosquito salivary glands independently of the normal transmission-associated environmental cues. Puf2- sporozoites exhibit genome-wide transcriptional changes that result in loss of gliding motility, cell traversal ability and reduction in infectivity, and, moreover, trigger metamorphosis typical of early Plasmodium intra-hepatic development. These data demonstrate that Puf2 is a key player in regulating sporozoite developmental control, and imply that transformation of salivary gland-resident sporozoites into liver stage-like parasites is regulated by a post-transcriptional mechanism.
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Affiliation(s)
- Carina S. S. Gomes-Santos
- Malaria Unit, Instituto de Medicina Molecular, Lisboa,
Portugal
- PhD Programme in Experimental Biology and Biomedicine, Center for
Neuroscience and Cell Biology, University of Coimbra, Coimbra,
Portugal
| | - Joanna Braks
- Leiden Malaria Research Group, Parasitology, Leiden University Medical
Centre, Leiden, The Netherlands
| | | | - Céline Carret
- Molecular Parasitology Unit, Instituto de Medicina Molecular, Lisbon,
Portugal
| | - Ana Rita Gomes
- Molecular Parasitology Unit, Instituto de Medicina Molecular, Lisbon,
Portugal
| | - Arnab Pain
- Pathogen Genetics Group, Wellcome Trust Sanger Institute, Cambridge,
United Kingdom
- Computational Bioscience Research Center (CBRC), Chemical Life Sciences
and Engineering Division, King Abdullah University of Science and Technology
(KAUST), Thuwal, Kingdom of Saudi Arabia
| | - Theresa Feltwell
- Pathogen Genetics Group, Wellcome Trust Sanger Institute, Cambridge,
United Kingdom
| | - Shahid Khan
- Leiden Malaria Research Group, Parasitology, Leiden University Medical
Centre, Leiden, The Netherlands
| | - Andrew Waters
- Leiden Malaria Research Group, Parasitology, Leiden University Medical
Centre, Leiden, The Netherlands
- Division of Infection and Immunity, Institute of Biomedical Life Sciences
and Wellcome Centre for Molecular Parasitology, Glasgow Biomedical Research
Centre, University of Glasgow, Glasgow, Scotland
- * E-mail: (GRM); (AW); (MM)
| | - Chris Janse
- Leiden Malaria Research Group, Parasitology, Leiden University Medical
Centre, Leiden, The Netherlands
| | - Gunnar R. Mair
- Molecular Parasitology Unit, Instituto de Medicina Molecular, Lisbon,
Portugal
- * E-mail: (GRM); (AW); (MM)
| | - Maria M. Mota
- Malaria Unit, Instituto de Medicina Molecular, Lisboa,
Portugal
- * E-mail: (GRM); (AW); (MM)
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67
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Müller K, Matuschewski K, Silvie O. The Puf-family RNA-binding protein Puf2 controls sporozoite conversion to liver stages in the malaria parasite. PLoS One 2011; 6:e19860. [PMID: 21673790 PMCID: PMC3097211 DOI: 10.1371/journal.pone.0019860] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2011] [Accepted: 04/06/2011] [Indexed: 12/11/2022] Open
Abstract
Malaria is a vector-borne infectious disease caused by unicellular, obligate intracellular parasites of the genus Plasmodium. During host switch the malaria parasite employs specialized latent stages that colonize the new host environment. Previous work has established that gametocytes, sexually differentiated stages that are taken up by the mosquito vector, control expression of genes required for mosquito colonization by translational repression. Sexual parasite development is controlled by a DEAD-box RNA helicase of the DDX6 family, termed DOZI. Latency of sporozoites, the transmission stage injected during an infectious blood meal, is controlled by the eIF2alpha kinase IK2, a general inhibitor of protein synthesis. Whether RNA-binding proteins participate in translational regulation in sporozoites remains to be studied. Here, we investigated the roles of two RNA-binding proteins of the Puf-family, Plasmodium Puf1 and Puf2, during sporozoite stage conversion. Our data reveal that, in the rodent malaria parasite P. berghei, Puf2 participates in the regulation of IK2 and inhibits premature sporozoite transformation. Inside mosquito salivary glands puf2⁻ sporozoites transform over time to round forms resembling early intra-hepatic stages. As a result, mutant parasites display strong defects in initiating a malaria infection. In contrast, Puf1 is dispensable in vivo throughout the entire Plasmodium life cycle. Our findings support the notion of a central role for Puf2 in parasite latency during switch between the insect and mammalian hosts.
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Affiliation(s)
- Katja Müller
- Max Planck Institute for Infection Biology, Parasitology Unit, Berlin, Germany
| | - Kai Matuschewski
- Max Planck Institute for Infection Biology, Parasitology Unit, Berlin, Germany
| | - Olivier Silvie
- Max Planck Institute for Infection Biology, Parasitology Unit, Berlin, Germany
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68
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Blocking Plasmodium falciparum Malaria Transmission with Drugs: The Gametocytocidal and Sporontocidal Properties of Current and Prospective Antimalarials. Pharmaceuticals (Basel) 2010. [PMCID: PMC4052541 DOI: 10.3390/ph4010044] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Drugs that kill or inhibit the sexual stages of Plasmodium could potentially amplify or synergize the impact of other interventions by blocking transmission to mosquitoes. Primaquine and other 8-aminoquinolines have long offered such potential, but safety and other concerns have limited their use. Although transmission-blocking properties are not often a priority of drug discovery efforts, a number of interesting gametocytocidal and/or sporontocidal drug candidates have emerged in recent years. Some still bear significant technical and safety concerns, while others have passed clinical trials and are on the verge of entering the antimalarial armamentarium. Recent advances in our knowledge of gametocyte differentiation, gametogenesis and sporogony have also led to the identification of a large array of potential new targets for drugs that might interfere with malaria transmission. This review examines the properties of existing and prospective drugs, mechanisms of action, counter-indications and their potential role in regional malaria elimination efforts.
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69
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Aly ASI, Lindner SE, MacKellar DC, Peng X, Kappe SHI. SAP1 is a critical post-transcriptional regulator of infectivity in malaria parasite sporozoite stages. Mol Microbiol 2010; 79:929-39. [PMID: 21299648 DOI: 10.1111/j.1365-2958.2010.07497.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Plasmodium salivary gland sporozoites upregulate expression of a unique subset of genes, collectively called the UIS (upregulated in infectious sporozoites). Many UIS were shown to be essential for early liver stage development, although little is known about their regulation. We previously identified a conserved sporozoite-specific protein, SAP1, which has an essential role in Plasmodium liver infection. Targeted deletion of SAP1 in Plasmodium yoelii caused the depletion of a number of selectively tested UIS transcripts in sporozoites, resulting in a complete early liver stage arrest. Here, we use a global gene expression survey to more comprehensively identify transcripts that are affected by SAP1 deletion. We find an effect upon both the transcript abundance of UIS genes, as well as of select genes previously not grouped as UIS. Importantly, we show that the lack of SAP1 causes the specific degradation of these transcripts. Collectively, our data suggest that SAP1 is involved in a selective post-transcriptional mechanism to regulate the abundance of transcripts critical to the infectivity of sporozoites. Although Pysap1(-) sporozoites are depleted of many of these important transcripts, they confer long-lasting sterile protection against wild-type sporozoite challenge in mice. SAP1 is therefore an appealing candidate locus for attenuation of Plasmodium falciparum.
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Affiliation(s)
- Ahmed S I Aly
- Seattle Biomedical Research Institute, Seattle, WA 98109, USA
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70
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Hughes KR, Philip N, Lucas Starnes G, Taylor S, Waters AP. From cradle to grave: RNA biology in malaria parasites. WILEY INTERDISCIPLINARY REVIEWS-RNA 2010; 1:287-303. [DOI: 10.1002/wrna.30] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Katie R. Hughes
- Division of Infection and Immunity, Faculty of Biomedical Life Sciences, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow G12 8TA, Scotland, UK
- Wellcome Centre for Molecular Parasitology, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow G12 8TA, Scotland, UK
| | - Nisha Philip
- Division of Infection and Immunity, Faculty of Biomedical Life Sciences, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow G12 8TA, Scotland, UK
- Wellcome Centre for Molecular Parasitology, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow G12 8TA, Scotland, UK
| | - G. Lucas Starnes
- Division of Infection and Immunity, Faculty of Biomedical Life Sciences, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow G12 8TA, Scotland, UK
- Wellcome Centre for Molecular Parasitology, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow G12 8TA, Scotland, UK
| | - Sonya Taylor
- Division of Infection and Immunity, Faculty of Biomedical Life Sciences, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow G12 8TA, Scotland, UK
- Wellcome Centre for Molecular Parasitology, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow G12 8TA, Scotland, UK
| | - Andrew P. Waters
- Division of Infection and Immunity, Faculty of Biomedical Life Sciences, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow G12 8TA, Scotland, UK
- Wellcome Centre for Molecular Parasitology, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow G12 8TA, Scotland, UK
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Abstract
In the burgeoning field of Plasmodium gene expression, there are--to borrow some famous words from a former U.S. Secretary of Defense--"known knowns, known unknowns, and unknown unknowns." This is in itself an important achievement, since it is only in the past decade that facts have begun to move from the third category into the first. Nevertheless, much remains in the middle ground of known or suspected "unknowns." It is clear that the malaria parasite controls vital virulence processes such as host cell invasion and cytoadherence at least partly via epigenetic mechanisms, so a proper understanding of epigenetic transcriptional control in this organism should have great clinical relevance. Plasmodium, however, is an obligate intracellular parasite: it operates not in a vacuum but rather in the complicated context of its metazoan hosts. Therefore, as valuable data about the parasite's basic epigenetic machinery begin to emerge, it becomes increasingly important to relate in vitro studies to the situation in vivo. This review will focus upon the challenge of understanding Plasmodium epigenetics in an integrated manner, in the human and insect hosts as well as the petri dish.
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