Transcript-level responses of Plasmodium falciparum to thiostrepton
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ABSTRACT: Abstract: The antimalarial activity of the antibiotic thiostrepton has long been attributed to inhibition of apicoplast protein synthesis through binding of apicoplast ribosomal RNA. However, the kinetics of parasite death upon thiostrepton treatment differ from those seen for other inhibitors of apicoplast housekeeping functions. We have analysed global changes in gene expression of the malaria parasite, Plasmodium falciparum, in an attempt to shed light on the responses of the parasite to this drug. Our results indicate a delay in gene expression profiles of thiostrepton-treated parasites. A small number of genes appear to be regulated outside of this trend; our data suggest a response from genes encoding components of the mitochondrial translational machinery, while little response is seen from genes encoding apicoplast-targeted proteins. Our findings are consistent with an effect of thiostrepton on mitochondrial protein synthesis, and thus warrant a re-evaluation of the target of thiostrepton in Plasmodium. They also provide some suggestion of mitochondrion – nucleus signalling in the parasite. 3 biological replicates each for treated and untreated: control (1/2000 DMSO) and LD70 thiostrepton, respectively
Project description:Abstract: The mitochondrial electron transport chain is essential to Plasmodium and is the target of the antimalarial drug atovaquone. The mitochondrial genomes of Plasmodium sp. are the most reduced known, and the majority of mitochondrial proteins are encoded in the nucleus and imported into the mitochondrion post-translationally. Many organisms have signalling pathways between the mitochondria and the nucleus to regulate the expression of nuclear-encoded mitochondrially-targeted proteins, for example in response to mitochondrial dysfunction. We have studied the gene expression profiles of synchronous Plasmodium falciparum treated with an LD50 concentration of the complex III inhibitor antimycin A, to investigate whether such pathways exist in the parasite. There was a broad perturbation of gene expression. Some effects were attributable to a delay in the gene expression phase of drug-treated parasites. However, our data also indicated regulation of mitochondrial stress response genes and genes involved in pyrimidine biosynthesis. 3 biological replicates each for treated and untreated: control (1/2000 DMSO) and LD50 antimycin A, respectively. Normalised microarray data for antimycin A-treated parasites were contrasted against untreated (DMSO) controls.
Project description:Abstract: The antimalarial activity of the antibiotic thiostrepton has long been attributed to inhibition of apicoplast protein synthesis through binding of apicoplast ribosomal RNA. However, the kinetics of parasite death upon thiostrepton treatment differ from those seen for other inhibitors of apicoplast housekeeping functions. We have analysed global changes in gene expression of the malaria parasite, Plasmodium falciparum, in an attempt to shed light on the responses of the parasite to this drug. Our results indicate a delay in gene expression profiles of thiostrepton-treated parasites. A small number of genes appear to be regulated outside of this trend; our data suggest a response from genes encoding components of the mitochondrial translational machinery, while little response is seen from genes encoding apicoplast-targeted proteins. Our findings are consistent with an effect of thiostrepton on mitochondrial protein synthesis, and thus warrant a re-evaluation of the target of thiostrepton in Plasmodium. They also provide some suggestion of mitochondrion – nucleus signalling in the parasite.
Project description:Plasmodium yoelii YM asexual blood stage parasites express multiple members of the py235 gene family, part of the super-family of genes including those coding for Plasmodium vivax reticulocyte binding proteins and Plasmodium falciparum RH proteins. Dr Tony Holder's laboratory (NIMR, London) has been successful in deleting one of the RH family genes (Py01365) by transfection and insertion of the TgDHFR gene, and cloned the resulting parasite in YM background. The gene expression patterns of the mutant parasite line were compared to that of the wild type YM parasite.
Project description:During red-blood-cell-stage infection of Plasmodium falciparum, the parasite undergoes repeated rounds of replication, egress, and invasion. Erythrocyte invasion involves specific interactions between host cell receptors and parasite ligands and coordinated expression of genes specific to this step of the life cycle. We show that a parasite-specific bromodomain protein, PfBDP1, binds to chromatin at transcriptional start sites of invasion-related genes and directly controls their expression. Conditional PfBDP1 knockdown causes a dramatic defect in parasite invasion and growth and results in transcriptional downregulation of multiple invasion-related genes at a time point critical for invasion. Conversely, PfBDP1 overexpression enhances expression of these same invasion-related genes. PfBDP1 binds to acetylated histone H3 and a second bromodomain protein, PfBDP2, suggesting a potential mechanism for gene recognition and control. Collectively, these findings show that PfBDP1 critically coordinates expression of invasion genes and indicate that targeting PfBDP1 could be an invaluable tool in malaria eradication. ChIPseq mapping of the genome wide enrichment profile of the P. falciparum bromodomain protein PfBDP1 in two parasite stages and correlation with RNAseq expression data
Project description:Recent advances in high throughput sequencing methodologies allow the opportunity to probe in depth the transcriptomes of organisms including important human pathogens. In this project, we are using Illumina sequencing technology to analyze the transcriptome (RNA-Seq) of experimentally accessible stages of the mouse malaria parasite, P. chabaudi AS. The aim is to analyse cir gene expression during Plasmodium chabaudi infection and determine whether host genetic background can influence cir expression. This data is part of a pre-publication release. For information on the proper use of pre-publication data shared by the Wellcome Trust Sanger Institute (including details of any publication moratoria), please see http://www.sanger.ac.uk/datasharing/. Abstract: Transcriptome sequencing of blood stage P. chabaudi AS parasites grown under different host genetic backgrounds.
Project description:Transcriptional profiling of gametocyte non-producer lines in Plasmodium berghei Transcriptome of gametocyte non producer lines (natural and genetic KO) and parental (820) lines. The aim of the study was to identify key genes involved in the decision to commit to gametocytogenesis in Plasmodium berghei. These microarrays compare naturally selected lines that do not produce gametocytes, and the parental line and additionally a genetic knock out of AP2-G PBANKA_143750. Data published Sinha, Hughes, et, al Nature tbc. 2- colour microarray comparing to common background pool (containing all life cycle stages). Replicates of different life cycle stages of gametocyte non-producer lines and wild tye (WT) parental control lines
Project description:The combination therapy of the Artemisinin-derivative Artemether (ART) with Lumefantrine (LM) (Coartem®) is an important malaria treatment regimen in many endemic countries. Resistance to Artemisinin has already been reported, and it is feared that LM resistance (LMR) could also evolve quickly. Therefore molecular markers which can be used to track Coartem®efficacy are urgently needed. Often, stable resistance arises from initial, unstable phenotypes that can be identified in vitro. Here we have used the Plasmodium falciparum multidrug resistant reference strain V1S to induce LMR in vitro by culturing the parasite under continuous drug pressure for 16 months. The initial IC50 (inhibitory concentration that kills 50% of the parasite population) was 24 nM. The resulting resistant strain V1SLM, obtained after culture for an estimated 166 cycles under LM pressure, grew steadily in 378 nM of LM; this corresponds to 15 times the IC50 of the parental strain. However, after two weeks of culturing V1SLM in drug-free medium, the IC50 returned to that of the initial, parental strain V1S. This transient drug tolerance was associated with major changes in gene expression profiles: when we explored V1SLM using the PFSANGER Affymetrix custom array, we identified 184 differentially expressed (DE) genes; amongst those 18 putative transporters including the multidrug resistance gene (pfmdr1), the multidrug resistance associated protein (pfmrp1) and the V-type H+ pumping pyrophosphatase 2 (pfvp2). Moreover, our results showed significant enrichment of genes associated with fatty acid metabolism and a clear selective advantage for two genomic loci in parasites grown under LM drug pressure, suggesting these genes may contribute to LM response in P. falciparum and could prove useful as molecular markers to monitor LM susceptibility.
Project description:The increasing spread of drug-resistant malaria strains underscores the need for new antimalarial agents with novel modes of action (MOAs). Here, we describe a compound representative of a new class of antimalarials. This molecule, ACT-213615, potently inhibits in vitro erythrocytic growth of all tested Plasmodium falciparum strains, irrespective of their drug resistance properties, with IC(50) values in the low single-digit nanomolar range. Like the clinically used artemisinins, the compound equally and very rapidly affects all three asexual erythrocytic parasite stages. In contrast, microarray studies suggest that the MOA of ACT-213615 is different from that of the artemisinins and other known antimalarials. ACT-213615 is orally bioavailable in mice, exhibits activity in the murine P. berghei model and efficacy comparable to that of the reference drug chloroquine in the recently established P. falciparum SCID mouse model.ACT-213615 represents a new class of potent antimalarials that merits further investigation for its clinical potential. Histone deacetylase (HDACs) inhibitors are being intensively pursued as potential new antimalarial drugs, and are also emerging as valuable tools for investigating transcriptional control in malaria parasites. In this study, the genome-wide transcriptional effects of three structurally related hydroxamate HDAC inhibitors were profiled in Plasmodium falciparum, the most lethal of the malaria parasite species that infects humans. Trophozoite-stage P. falciparum cells were treated with ACT-213615 for increasing amount of time at IC50 concentration and cells were harvested in parralled with DMSO treated controls for microarray-based transcriptional profiling.
Project description:The nuclear proteome of mixed populations of Plasmodium falciparum was explored by GeLC-MS/MS and 2D-LC-MS/MS with a peptide exclusion procedure in order to increase the detection of low abundant proteins such as those involved in gene expression.