Patterns of heterochromatin distribution alterations linked to transcriptional changes at Plasmodium falciparum clonally variant gene loci [gene expression]
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PROVIDER: PRJNA858441 | ENA |
REPOSITORIES: ENA
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Project description:The survival of malaria parasites in the changing human blood environment largely depends on their ability to alter gene expression by epigenetic mechanisms. The active state of Plasmodium falciparum clonally variant genes is associated with euchromatin characterized by the histone mark H3K9ac, whereas the silenced state is characterized by H3K9me3-based heterochromatin. However, the localization of the euchromatin-heterochromatin transitions associated with expression switches in different clonally variant genes has not been characterized. Here we compared the distribution of heterochromatin between subclones of the same genetic background with different patterns of expressed and silenced clonally variant genes to identify at a genome-wide level the patterns associated with the different transcriptional states. We found that de novo heterochromatin formation or complete disruption of a heterochromatin domain are relatively rare events, and in the majority of loci expression switches can be explained by expansion or retraction of heterochromatin. We describe different modalities of heterochromatin changes linked to transcriptional differences, revealing a complex scenario. Despite this complexity, heterochromatin distribution patterns generally enable prediction of the transcriptional state of clonally variant genes. Some subclones expressed and had in an active chromatin state several var genes simultaneously. We also found that heterochromatin levels in the putative regulatory region of the gdv1-as non-coding RNA, previously involved in sexual commitment, varied between parasite lines with different sexual conversion rates. Gene expression data for subclones A7, E5 and B11 (3D7-B stock).
2022-11-03 | GSE208131 | GEO
Project description:The survival of malaria parasites in the changing human blood environment largely depends on their ability to alter gene expression by epigenetic mechanisms. The active state of Plasmodium falciparum clonally variant genes is associated with euchromatin characterized by the histone mark H3K9ac, whereas the silenced state is characterized by H3K9me3-based heterochromatin. However, the localization of the euchromatin-heterochromatin transitions associated with expression switches in different clonally variant genes has not been characterized. Here we compared the distribution of heterochromatin between subclones of the same genetic background with different patterns of expressed and silenced clonally variant genes to identify at a genome-wide level the patterns associated with the different transcriptional states. We found that de novo heterochromatin formation or complete disruption of a heterochromatin domain are relatively rare events, and in the majority of loci expression switches can be explained by expansion or retraction of heterochromatin. We describe different modalities of heterochromatin changes linked to transcriptional differences, revealing a complex scenario. Despite this complexity, heterochromatin distribution patterns generally enable prediction of the transcriptional state of clonally variant genes. Some subclones expressed and had in an active chromatin state several var genes simultaneously. We also found that heterochromatin levels in the putative regulatory region of the gdv1-as non-coding RNA, previously involved in sexual commitment, varied between parasite lines with different sexual conversion rates.
2022-11-03 | GSE208560 | GEO
Project description:Patterns of heterochromatin distribution alterations linked to transcriptional changes at Plasmodium falciparum clonally variant gene loci
| PRJNA860104 | ENA
Project description:Patterns of heterochromatin distribution alterations linked to transcriptional changes at Plasmodium falciparum clonally variant gene loci [ChIP-seq]
| PRJNA860106 | ENA
Project description:This SuperSeries is composed of the SubSeries listed below.
2022-11-03 | GSE208561 | GEO
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:In the malaria parasite Plasmodium falciparum, changes in the distribution of heterochromatin at specific loci regulate the expression of clonally variant genes (CVGs), which play fundamental roles in host-parasite interactions. In addition to differences in heterochromatin between individual parasites associated with variant expression of CVGs, changes in heterochromatin distribution associated with different developmental stages have been described. However, while stage II/III gametocytes (sexual precursors) have an altered distribution of heterochromatin compared with asexual blood stages, it is unclear if heterochromatin changes already occur at the very early stages of sexual development. Here we used a transgenic parasite line in which sexual conversion can be conditionally induced to characterise the changes in heterochromatin distribution associated with the earliest stages of sexual development. We found that there were essentially no changes in sexual rings or stage I gametocytes compared with asexual blood stages, and remodelling of heterochromatin started at stage II or III of gametocyte development, with changes similar to those previously described in parasites of a different genetic background. Therefore, global redistribution of heterochromatin does not appear to play a role in the initial steps of sexual development. We also found that, for several genes, changes in expression associated with sexual development precede changes in the heterochromatin at their locus.
2024-10-09 | GSE252334 | GEO
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 malaria parasite Plasmodium falciparum relies on clonally variant gene expression in order to escape immune recognition and secure continuous proliferation during blood stage infection. Here, we studied the role of heterochromatin protein 1 (HP1), an evolutionary conserved regulator of heritable gene silencing, in the biology of P. falciparum blood stage parasites. We demonstrate that conditional PfHP1 depletion de-represses hundreds of heterochromatic virulence genes and disrupts the elusive mechanism underlying mutually exclusive expression and antigenic variation of PfEMP1. Intriguingly, we also discovered that the PfHP1-dependent regulation of an ApiAP2 transcription factor controls the switch from asexual parasite proliferation to sexual differentiation. This uncovers the first mechanistic insight into the unknown pathway triggering gametocyte conversion and establishes a new concept of HP1-dependent cell fate decision in unicellular eukaryotes. P. falciparum 3D7 parasites expressing endogenous PfHP1-GFP-DD were grown in presence of 4nM WR/625nM Shield-1 (3D7/HP1ON) or 4nM WR (3D7/HP1OFF). RNA extracted from these samples at eleven consecutive time points each was processed for microarray analysis.
2014-07-09 | E-GEOD-53176 | biostudies-arrayexpress
Project description:The survival of malaria parasites in the changing human blood environment largely depends on their ability to alter gene expression by epigenetic mechanisms. The active state of Plasmodium falciparum clonally variant genes (CVGs) is associated with euchromatin characterized by the histone mark H3K9ac, whereas the silenced state is characterized by H3K9me3-based heterochromatin. Expression switches are linked to euchromatin-heterochromatin transitions, but these transitions have not been characterized for the majority of CVGs. To define the heterochromatin distribution patterns associated with the alternative transcriptional states of CVGs, we compared H3K9me3 occupancy at a genome-wide level among several parasite subclones of the same genetic background that differed in the transcriptional state of many CVGs. We found that de novo heterochromatin formation or the complete disruption of a heterochromatin domain is a relatively rare event, and for the majority of CVGs, expression switches can be explained by the expansion or retraction of heterochromatin domains. We identified different modalities of heterochromatin changes linked to transcriptional differences, but despite this complexity, heterochromatin distribution patterns generally enable the prediction of the transcriptional state of specific CVGs. We also found that in some subclones, several var genes were simultaneously in an active state. Furthermore, the heterochromatin levels in the putative regulatory region of the gdv1 antisense noncoding RNA, a regulator of sexual commitment, varied between parasite lines with different sexual conversion rates. IMPORTANCE The malaria parasite P. falciparum is responsible for more than half a million deaths every year. P. falciparum clonally variant genes (CVGs) mediate fundamental host-parasite interactions and play a key role in parasite adaptation to fluctuations in the conditions of the human host. The expression of CVGs is regulated at the epigenetic level by changes in the distribution of a type of chromatin called heterochromatin. Here, we describe at a genome-wide level the changes in the heterochromatin distribution associated with the different transcriptional states of CVGs. Our results also reveal a likely role for heterochromatin at a particular locus in determining the parasite investment in transmission to mosquitoes. Additionally, this data set will enable the prediction of the transcriptional state of CVGs from epigenomic data, which is important for the study of parasite adaptation to the conditions of the host in natural malaria infections.
| S-EPMC9927496 | biostudies-literature