Ontology highlight
ABSTRACT:
PROVIDER: PRJNA802886 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR17867047_1.fastq.gz | Fastqsanger.gz | |||
| SRR17867047_2.fastq.gz | Fastqsanger.gz | |||
| SRR17867048_1.fastq.gz | Fastqsanger.gz | |||
| SRR17867048_2.fastq.gz | Fastqsanger.gz | |||
| SRR17867049_1.fastq.gz | Fastqsanger.gz |
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Project description:Rrp6-mediated heterochromatin surveillance secures antigenic variation and sexual commitment of human malaria parasites
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Project description:This experiment studies the effect of knocking out the transcriptional regulator SIR2 in 3D7 parasites. RNA was harvested from ring-stage parasites at 8 hours post-infection. Keywords = SIR2 Keywords = epigenetic regulation Keywords = antigenic variation Keywords = var Keywords = Plasmodium falciparum Keywords: other
2005-03-08 | GSE2369 | GEO
Project description:The asexual forms of the malaria parasite Plasmodium falciparum are uniquely adapted for chronic persistence in human red blood cells, continuously evading the immune system using an epigenetically regulated process. However, parasite survival on a population level also requires transmission of sexual parasite forms to subsequent human hosts. Here, we reveal that the essential nuclear gene, P. falciparum histone deacetylase 2 (PfHda2), silences specific subsets of genes involved in antigenic variation or conversion to sexual stages. Two parallel timecourses resulting in a total of 22 samples (11 wildtype, 11 PfHda2 knockdown) were hybridized against a Cy3-labeled reference pool of 3D7 mixed stage parasites on a two-color array.
2014-02-11 | E-GEOD-54806 | biostudies-arrayexpress
Project description:Single-cell RNA-sequencing is revolutionising our understanding of seemingly homogeneous cell populations but has not yet been widely applied to single-celled organisms. Transcriptional variation in unicellular malaria parasites from the Plasmodium genus is associated with critical phenotypes including red blood cell invasion and immune evasion, yet transcriptional variation at an individual parasite level has not been examined in depth. Here, we describe the adaptation of a single-cell RNA-sequencing (scRNA-seq) protocol to deconvolute transcriptional variation for more than 500 individual parasites of both rodent and human malaria comprising asexual and sexual life-cycle stages. We uncover previously hidden discrete transcriptional signatures during the pathogenic part of the life cycle, suggesting that expression over development is not as continuous as commonly thought. In transmission stages, we find novel, sex-specific roles for differential expression of contingency gene families that are usually associated with immune evasion and pathogenesis.
2017-02-08 | E-ERAD-611 | biostudies-arrayexpress
Project description:Variation of surface adhesins is a critical mediator of virulence and immune evasion in many medically important microbes. Phenotypic switching has been linked to transcriptional changes and the function of chromatin proteins, but the determinants of the rate of phenotypic switching remain poorly defined. We analyzed epigenetic switching of the Plasmodium falciparum erythrocyte invasion ligand PfRh4. By introducing a prokaryotic Dam methylase, we demonstrate that parasites selected for in vivo PfRh4 activation show a reversible increase in promoter accessibility while exhibiting perinuclear repositioning of the locus from a silent to a conserved activation domain. Forced activation of a proximal gene results in a similar level of repositioning of the PfRh4 locus into this domain and a concomitant increase in PfRh4 activation in a sub-population of parasites, with promoter accessibility occurring only at actively transcribed loci. Thus, we reveal two distinct epigenetic mechanisms regulating the expression of a malaria virulence gene. To examine the correlation between changes in gene expression induced by treatment with a high dose of trichostatin A (TSA) and the associated changes in chromatin accessibility. Plasmodium falciparum was treated (or not, control) with 100nm or 500nm TSA, and then the expression profiles were analyzed.
2012-10-13 | E-GEOD-41567 | biostudies-arrayexpress
Project description:The genomes of most protozoa encode families of variant surface antigens, whose mutually exclusive changes in expression allow parasitic microorganisms to evade the host immune response1. It is widely assumed that antigenic variation in protozoan parasites is accomplished by the spontaneous appearance within the population of cells expressing antigenic variants that escape antibody-mediated cytotoxicity1,2. Here we show, both in vitro and in animal infections, that antibodies to Variant-specific Surface Proteins (VSPs) of the intestinal parasite Giardia lamblia are not cytotoxic; instead, anti-VSP antibodies induce VSP clustering into microdomains, triggering a massive release of microvesicles carrying the original VSP and switching in expression to different VSPs by a calcium-dependent process. Surface microvesiculization and antigenic switching are also stimulated when Trypanosoma brucei and Tetrahymena thermophila are confronted to antibodies directed to their GPI-anchored variable surface glycoproteins. This novel mechanism of antigen clearance throughout its release into microvesicles coupled to the stochastic induction of new phenotypic variants not only changes the current paradigm of spontaneous antigenic switching but also provides a new framework for understanding the course of infections as a host/parasite adaptive process.
2023-05-10 | PXD031141 | Pride
Project description:The parasite Trypanosoma brucei periodically changes the expression of protective variant surface glycoproteins (VSGs) to evade its host’s immune system in a process known as antigenic variation. One route to change VSG expression is the transcriptional activation of a previously silent VSG expression site (ES), a subtelomeric region containing the VSG genes. Homologous recombination of a different VSG from a large reservoir into the active ES represents another route. The conserved histone methyltransferase DOT1B is involved in transcriptional silencing of inactive ES and influences ES switching kinetics. The molecular machinery that enables DOT1B to execute these regulatory functions remains elusive, however. To better understand DOT1B-mediated regulatory processes, we purified DOT1B-associated proteins using complementary biochemical approaches. We identified several novel DOT1B-interactors. One of these was the Ribonuclease H2 complex, previously shown to resolve RNA-DNA hybrids, maintain genome integrity, and play a role in antigenic variation. Our study revealed that DOT1B depletion results in an increase in RNA-DNA hybrids, accumulation of DNA damage and ES switching events. Surprisingly, a similar pattern of VSG deregulation was observed in Ribonuclease H2 mutants. We propose that both proteins act together in resolving R-loops to ensure genome integrity and contribute to the tightly-regulated process of antigenic variation.
2021-10-25 | PXD028588 | Pride
Project description:Epigenetic processes are the main conductors of phenotypic variation in eukaryotes. The malaria parasite Plasmodium falciparum employs antigenic variation of the major surface antigen PfEMP1, encoded by 60 var genes, to evade acquired immune responses. PfEMP1 also mediates sequestration of infected erythrocytes in the microvasculature, which is directly linked to severe malaria outcomes. Antigenic variation of PfEMP1 occurs through in situ switches in mono-allelic var gene transcription, which is PfSIR2-dependent and associated with the presence of repressive H3K9me3 marks at silenced loci. Here, we show that the P. falciparum ortholog of heterochromatin protein 1 (PfHP1) binds to H3K9me3 and constitutes a major component of heterochromatin in perinuclear chromosome end clusters. High-resolution genome-wide chromatin immuno-precipitation demonstrates the striking association of PfHP1 with non-syntenic virulence gene arrays in subtelomeric and chromosome-internal islands. These include not only var genes but the majority of P. falciparum lineage-specific gene families coding for exported proteins involved in host-parasite interactions. Over-expression of PfHP1 resulted in decreased expression of a small number of (virulance) genes and indicated the presence of well-defined heterochromatic boundaries.. In summary, we uncover an unprecedented function of HP1 as a mayor regulator of virulence gene silencing and phenotypic variation, which will be instrumental for our understanding of this widely used survival strategy of unicellular pathogens. one experimental sample
2010-05-06 | E-GEOD-17029 | biostudies-arrayexpress
Project description:The determinants of transcriptional regulation in malaria parasites remain elusive. The presence of a well-characterized gene expression cascade shared by different Plasmodium falciparum strains could imply that transcriptional regulation and its natural variation do not contribute significantly to the evolution of parasite drug resistance. To clarify the role of transcriptional variation as a source of stain-specific diversity in the most deadly malaria species and to find genetic loci that dictate variations in gene expression, we examined genome-wide expression level polymorphisms (ELPs) in a genetic cross between phenotypically distinct parasite clones. Significant variation in gene expression is observed through direct co-hybridizations of RNA from different P. falciparum clones. Nearly 18% of genes were regulated by a significant eQTL. The genetic determinants of most of these ELPs resided in hotspots that are physically distant from their targets. The most prominent regulatory locus, influencing 269 transcripts, coincided with a Chromosome 5 amplification event carrying the drug resistance gene, pfmdr1, and 13 other genes. Drug selection pressure in the Dd2 parental clone lineage led not only to a copy number change in the pfmdr1 gene but also to increased copies of putative neighboring regulatory factors that, in turn, broadly influence the transcriptional network. Previously unrecognized transcriptional variation, controlled by polymorphic regulatory genes and possibly master regulators within large copy number variants, contributes to sweeping phenotypic evolution in drug-resistant malaria parasites. Keywords: Segregation patterns of gene expression levels. A total of 36 test parasite samples (Dd2, HB3, and progeny) from a single time point in the parasite life cycle (18 hours post RBC invasion) were co-hybridized to a common reference HB3 sample, each a single replicate.
2010-05-16 | E-GEOD-12515 | biostudies-arrayexpress
Project description:PfEMP1 is a variable antigen displayed on red blood cells (RBCs) infected with the malaria parasite Plasmodium falciparum. PfEMP1 mediates binding of the infected cell to the endothelium of blood vessels, a major cause of severe manifestations of malaria. Each parasite encodes ∼60 different PfEMP1 variants of which only one is expressed at a time and switching between variants underlies immune evasion in the host and variant-specific severity of disease. PfEMP1 expression heterogeneity between parasites complicates its study and hampers genetic modification approaches as in many cells the modified locus is not expressed. Here we used selection linked integration to generate parasites all expressing the same PfEMP1 variant and permitting genomic modification of the expressed locus. Using this system, we study PfEMP1 trafficking, generate cell lines binding to all major endothelial receptors, survey the protein environment from functional PfEMP1 in the host cell and identify new proteins needed for PfEMP1 mediated sequestration. Overall, these approaches facilitate the study of the molecular and cellular biology of the key virulence factor of malaria parasites.
2024-09-01 | GSE275671 | GEO