Expression data of gene knockout Plasmodium falciparum clones
Ontology highlight
ABSTRACT:
ORGANISM(S): Plasmodium falciparum Plasmodium falciparum 3D7 Anopheles gambiae
PROVIDER: GSE47349 | GEO | 2013/05/25
SECONDARY ACCESSION(S): PRJNA205237
REPOSITORIES: GEO
Similar Datasets
Project description:The variant antigen, Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1), expressed on the surface of P. falciparum infected Red Blood Cells (iRBCs) is a critical virulence factor for malaria. Each parasite encodes 60 antigenically distinct var genes encoding PfEMP1s, but during infection the clonal parasite population expresses only one gene at a time before switching to the expression of a new variant antigen as an immune evasion mechanism to avoid the hostM-bM-^@M-^Ys antibody responses. The mechanism by which 59 of the 60 var genes are silenced remains largely unknown. We used microarrays to detail the global programme changes of gene expression caused by each gene knockout with a particular view towards which gene knockout results in transcriptional upregulation of the entire var gene family. Plasmodium falciparum clones, in each of which one of different histone lysine methylation modification enzyme genes was knocked out, were synchronized in the asexual stage and collected at indicated time points post invasion of erythrocytes for RNA extraction and hybridization on Affymetrix microarrays. We sought to identify the key epigenetic enzyme that controls silencing of the whole var gene family.
2013-05-25 | E-GEOD-47349 | biostudies-arrayexpress
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: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.
2009-09-03 | GSE17029 | GEO
Project description:The P. falciparum genome is equipped with several subtelomeric gene families that are implicated in parasite virulence and immune evasion. The members of these gene families are uniformly positioned within heterochromatic domains of the genome and are thus subject to variegated expression. The best-studied example is that of the var gene family encoding the major parasite virulence factor P. falciparum erythrocyte membrane protein 1 (PfEMP1). Transcriptional regulation of other subtelomeric gene families and their role in parasite biology is much less understood. Here, we investigated the mode of transcriptional control of var, rif, stevor, phist and pfmc-2tm families by comparative genome-wide transcriptional profiling of transgenic parasite lines. Our results establish a clear functional distinction between var and non-var transcriptional control mechanisms. Unlike var promoters, we find that promoters of non-var families are not silenced by default. Moreover, we show that mutually exclusive transcription is unique to the var gene family.
2011-09-02 | GSE31829 | GEO
Project description:Cerebral malaria is the most deadly manifestation of infection with Plasmodium falciparum. The pathology of cerebral malaria is characterised by the accumulation of infected erythrocytes in the microvasculature of the brain, due to parasite adhesins on the surface of infected erythrocytes binding to human receptors on microvascular endothelial cells. The parasite and host molecules involved in this interaction are unknown. We used the Human Brain Endothelial Cell line HBEC-5i to identify the malaria parasite ligands responsible for binding to human brain endothelial cells. Three P. falciparum strains (HB3, 3D7 and IT/FCR3) were selected for binding to HBEC5i and the whole transcriptome of selected and unselected parasites was analysed using a variant surface antigen-supplemented microarray chip. After selection, the only highly upregulated genes were a subset of group A-like var genes (HB3var3, 3D7_PFD0020c, ITvar7 and ITvar19), that showed 11 to >100-fold higher transcription levels in selected parasites. These genes are highly diverse in sequence, but do however show strong similarities in PfEMP1 architecture. Antibodies raised to the HB3var3 variant recognized the surface of infected erythrocytes and abolished the binding of infected erythrocytes to brain endothelial cells. The subset of Group A PfEMP1 variants identified here provides a new target for interventions to treat or prevent cerebral malaria.
2011-11-01 | GSE32211 | GEO
Project description:A variant of the TNFSF13B gene (BAFF-var) increases the production of the cytokine BAFF, up-regulating humoral immunity and increasing the risk for certain autoimmune diseases. BAFF-var was evolutionarily advantageous, most likely by increasing resistance to malaria infection. We assessed experimentally the role of BAFF-var in response to malaria antigens. Lysates of erythrocytes infected with Plasmodium falciparum (iRBCs) or left uninfected (uRBCs, control) were used to treat PBMCs with distinct BAFF genotypes. PBMCs purified from BAFF-var donors and treated with iRBCs showed different levels of specific cells, immunoglobulins and cytokines as compared with BAFF-WT. In particularly a relevant differential effect on mucosal immunity B subpopulations have been observed. RNA sequencing of total B cells, purified from PBMC treated with iRBCs or uRBCs, identified several transcripts differentially expressed including some that encoded proteins critical for the response to malaria infection. These findings point to specific immune cells and molecules through which the evolutionary selected BAFF-var may have improved fitness during P. falciparum infection.
2020-11-02 | GSE156102 | GEO
Project description:The completion of the Plasmodium falciparum clone 3D7 genome provides a basis on which to conduct comparative proteomics studies of this human pathogen. Here, we applied a high-throughput proteomics approach to identify new potential drug and vaccine targets and to better understand the biology of this complex protozoan parasite. We characterized four stages of the parasite life cycle (sporozoites, merozoites, trophozoites and gametocytes) by multidimensional protein identification technology. Functional profiling of over 2,400 proteins agreed with the physiology of each stage. Unexpectedly, the antigenically variant proteins of var and rif genes, defined as molecules on the surface of infected erythrocytes, were also largely expressed in sporozoites. The detection of chromosomal clusters encoding co-expressed proteins suggested a potential mechanism for controlling gene expression. Keywords: ordered
2002-12-22 | E-GEOD-92 | biostudies-arrayexpress
Project description:P. falciparum undergoes antigenic variation during its life cycle in the human host. To accomplish this, the malaria parasite has developed mechanisms that ensure the expression of a single member of the var gene family to produce one of the PfEMP1 variant proteins. Here we carry out RNA-seq and ChIP-seq analyses of histone modifications to explore transcriptional and epigenomic changes taking place between the transmissible stages of the parasite i.e. gametocytes present in human blood and sporozoites present in the mosquito salivary glands. We find that most var genes are expressed at low levels in gametocytes but a single var gene is selected during the oocyst stage in the mosquito. Clonal expression of a specific var gene is accompanied by the establishment of specific histone modification patterns in the active and inactive genes. These modifications are epigenetically transmitted from the oocyst to the infective sporozoite stage, where expression of the active var gene is amplified by the transcription of an antisense lncRNA. The findings suggest a critical role for the mosquito immune system in determining the choice of var gene activation prior to transmission to the human host.
2017-01-18 | GSE68667 | GEO
Project description:The completion of the Plasmodium falciparum clone 3D7 genome provides a basis on which to conduct comparative proteomics studies of this human pathogen. Here, we applied a high-throughput proteomics approach to identify new potential drug and vaccine targets and to better understand the biology of this complex protozoan parasite. We characterized four stages of the parasite life cycle (sporozoites, merozoites, trophozoites and gametocytes) by multidimensional protein identification technology. Functional profiling of over 2,400 proteins agreed with the physiology of each stage. Unexpectedly, the antigenically variant proteins of var and rif genes, defined as molecules on the surface of infected erythrocytes, were also largely expressed in sporozoites. The detection of chromosomal clusters encoding co-expressed proteins suggested a potential mechanism for controlling gene expression. Keywords: ordered
2002-12-23 | GSE92 | GEO
Project description:The P. falciparum genome is equipped with several subtelomeric gene families that are implicated in parasite virulence and immune evasion. The members of these gene families are uniformly positioned within heterochromatic domains of the genome and are thus subject to variegated expression. The best-studied example is that of the var gene family encoding the major parasite virulence factor P. falciparum erythrocyte membrane protein 1 (PfEMP1). Transcriptional regulation of other subtelomeric gene families and their role in parasite biology is much less understood. Here, we investigated the mode of transcriptional control of var, rif, stevor, phist and pfmc-2tm families by comparative genome-wide transcriptional profiling of transgenic parasite lines. Our results establish a clear functional distinction between var and non-var transcriptional control mechanisms. Unlike var promoters, we find that promoters of non-var families are not silenced by default. Moreover, we show that mutually exclusive transcription is unique to the var gene family. 3D7 wild-type parasites were transfected with constructs carrying eight different promoters that drive expression of the drug-selectable marker hdhfr-gfp. Thereof seven promoters are members of the multigene families upsA var, upsB var, upsC var, rif, stevor, phistb and pfmc-2tm. The cam promoter was used as transfection-based control and also a wild-type 3D7 cell line was included as control. These nine cell lines were subjected to genome-wide transcriptional profiling. Parasites were synchronized to obtain an 8 hour growth window and were harvested at four consecutive timepoints (TP): TP1 (6-14 hours post-invasion (hpi)); TP2 (14-22 hpi); TP3 (22-30 hpi); TP4 (30-38 hpi) to monitor intra- and inter-family specific linkage of multigene family expression.
2011-09-01 | E-GEOD-31829 | biostudies-arrayexpress