Plasmodium falciparum
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ABSTRACT:
PROVIDER: PRJNA145129 | ENA |
REPOSITORIES: ENA
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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:The process of erythrocyte invasion by merozoites of Plasmodium falciparum involves multiple steps, including the formation of a moving junction characterized by the redundancy of many of the receptor-ligand interactions involved. Several of the parasite proteins that interact with erythrocyte receptors or participate in other steps of the process of invasion are encoded by small subtelomerically-located multigene families of four to seven members. We report here that members of the multigene families pfRh, eba, rhopH1/clag and acbp exist in either an active or a silenced state. In the case of two members of the rhopH1/clag family, clag3.1 and clag3.2, expression was mutually exclusive. Silencing occurred in the absence of detectable DNA alterations, suggesting that it is transmitted epigenetically. This was unambiguously demonstrated for eba-140, which was silenced by the formation of facultative heterochromatin. Our data demonstrate that variant expression, epigenetic silencing and mutually exclusive expression in Plasmodium are not unique to genes encoding proteins exported to the surface of the erythrocyte like var genes but also occur for genes involved in host cell invasion..
2007-11-26 | E-SGRP-9 | biostudies-arrayexpress
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
Project description:The mutually exclusive expression of virulence genes is critical for the immune evasion and pathogenesis of malaria parasites, Plasmodium falciparum, in human host. The three-dimensional genome structure has emerged as a new factor involved in transcriptional regulation of virulence gene families in the parasites. However, the mechanism controlling this epigenetic regulation pathway remains elusive. Here, we have identified the highly conserved high mobility group protein HMGB1 as a critical architectural regulator in establishment of high-order genome structure via interaction with centromeres in P. falciparum. Genetic manipulation of Pfhmgb1 gene and Hi-C analysis showed that the boundary of telomere and centromere clusters in an opposite spatial relationship in the nucleus was disrupted upon hmgb1 knockout. The collapse of euchromatic centromere cluster from nuclear periphery towards the opposite heterochromatic telomere cluster triggered relocation of the original active var gene, which resulted in complete silence of the entire repertoire of var gene family. ChIP-seq and fluorescence assay analysis confirmed the specific interaction between PfHMGB1 and centromeres. Meanwhile, as in other eukaryotes, PfHMGB1 was also widely present on the promoter regions of a variety of genes and co-regulated transcription, including other non-var variant gene families, suggesting multiple dimensions of epigenetic gene regulation by PfHMGB1. Finally, the natural genome organization could be reconstructed by hmgb1 gene complementation, which rescued the mutually exclusive expression of virulence genes. Taken together, our work provides new insight into the evolution of biological functions of the HMG architectural superfamily in eukaryotes.
2021-04-14 | GSE141759 | GEO
Project description:The mutually exclusive expression of virulence genes is critical for the immune evasion and pathogenesis of malaria parasites, Plasmodium falciparum, in human host. The three-dimensional genome structure has emerged as a new factor involved in transcriptional regulation of virulence gene families in the parasites. However, the mechanism controlling this epigenetic regulation pathway remains elusive. Here, we have identified the highly conserved high mobility group protein HMGB1 as a critical architectural regulator in establishment of high-order genome structure via interaction with centromeres in P. falciparum. Genetic manipulation of Pfhmgb1 gene and Hi-C analysis showed that the boundary of telomere and centromere clusters in an opposite spatial relationship in the nucleus was disrupted upon hmgb1 knockout. The collapse of euchromatic centromere cluster from nuclear periphery towards the opposite heterochromatic telomere cluster triggered relocation of the original active var gene, which resulted in complete silence of the entire repertoire of var gene family. ChIP-seq and fluorescence assay analysis confirmed the specific interaction between PfHMGB1 and centromeres. Meanwhile, as in other eukaryotes, PfHMGB1 was also widely present on the promoter regions of a variety of genes and co-regulated transcription, including other non-var variant gene families, suggesting multiple dimensions of epigenetic gene regulation by PfHMGB1. Finally, the natural genome organization could be reconstructed by hmgb1 gene complementation, which rescued the mutually exclusive expression of virulence genes. Taken together, our work provides new insight into the evolution of biological functions of the HMG architectural superfamily in eukaryotes.
2021-04-14 | GSE141758 | GEO
Project description:The mutually exclusive expression of virulence genes is critical for the immune evasion and pathogenesis of malaria parasites, Plasmodium falciparum, in human host. The three-dimensional genome structure has emerged as a new factor involved in transcriptional regulation of virulence gene families in the parasites. However, the mechanism controlling this epigenetic regulation pathway remains elusive. Here, we have identified the highly conserved high mobility group protein HMGB1 as a critical architectural regulator in establishment of high-order genome structure via interaction with centromeres in P. falciparum. Genetic manipulation of Pfhmgb1 gene and Hi-C analysis showed that the boundary of telomere and centromere clusters in an opposite spatial relationship in the nucleus was disrupted upon hmgb1 knockout. The collapse of euchromatic centromere cluster from nuclear periphery towards the opposite heterochromatic telomere cluster triggered relocation of the original active var gene, which resulted in complete silence of the entire repertoire of var gene family. ChIP-seq and fluorescence assay analysis confirmed the specific interaction between PfHMGB1 and centromeres. Meanwhile, as in other eukaryotes, PfHMGB1 was also widely present on the promoter regions of a variety of genes and co-regulated transcription, including other non-var variant gene families, suggesting multiple dimensions of epigenetic gene regulation by PfHMGB1. Finally, the natural genome organization could be reconstructed by hmgb1 gene complementation, which rescued the mutually exclusive expression of virulence genes. Taken together, our work provides new insight into the evolution of biological functions of the HMG architectural superfamily in eukaryotes.
2021-04-14 | GSE141761 | GEO
Project description:The mutually exclusive expression of virulence genes is critical for the immune evasion and pathogenesis of malaria parasites, Plasmodium falciparum, in human host. The three-dimensional genome structure has emerged as a new factor involved in transcriptional regulation of virulence gene families in the parasites. However, the mechanism controlling this epigenetic regulation pathway remains elusive. Here, we have identified the highly conserved high mobility group protein HMGB1 as a critical architectural regulator in establishment of high-order genome structure via interaction with centromeres in P. falciparum. Genetic manipulation of Pfhmgb1 gene and Hi-C analysis showed that the boundary of telomere and centromere clusters in an opposite spatial relationship in the nucleus was disrupted upon hmgb1 knockout. The collapse of euchromatic centromere cluster from nuclear periphery towards the opposite heterochromatic telomere cluster triggered relocation of the original active var gene, which resulted in complete silence of the entire repertoire of var gene family. ChIP-seq and fluorescence assay analysis confirmed the specific interaction between PfHMGB1 and centromeres. Meanwhile, as in other eukaryotes, PfHMGB1 was also widely present on the promoter regions of a variety of genes and co-regulated transcription, including other non-var variant gene families, suggesting multiple dimensions of epigenetic gene regulation by PfHMGB1. Finally, the natural genome organization could be reconstructed by hmgb1 gene complementation, which rescued the mutually exclusive expression of virulence genes. Taken together, our work provides new insight into the evolution of biological functions of the HMG architectural superfamily in eukaryotes.
2021-04-14 | GSE141760 | GEO
Project description:Malaria caused by Plasmodium falciparum involves antigenic variation on the infected red blood cells through mutually exclusive expression of var genes. The repressed var genes have a distinct genome organization where they localize as a cluster near the nuclear periphery and are bound by PfHP1 (P. falciparum Heterochromatin Protein 1). However, the mode of regulation of var genes by PfHP1 remains unclear. In this study, we show that PfHP1 undergoes liquid-liquid phase separation (LLPS) in vitro in an RNA and DNA-dependent manner. Single-molecule DNA tethering experiments further revealed that AT-rich DNA sequences act as nucleation sites for the assembly and compaction of PfHP1-mediated heterochromatinization. We have also identified point mutations in the IDRs (intrinsically disordered regions) of PfHP1 that disrupt its phase separation as well as DNA compaction in vitro. An ectopic expression of PfHP1 phase separation and DNA compaction mutants led to dispersed nuclear localization, in contrast to the punctate appearance of the wild-type protein and altered chromatin binding at var genes. These results were corroborated with DiCre/loxP based conditional expression of the same PfHP1 mutants, which also led to the de-repression of multiple var genes (as many as 54 out of 60 var genes), mimicking the phenotype of PfHP1 depletion mutants. To assess the dynamic properties of PfHP1 condensates in vivo, we performed fluorescence recovery after photobleaching (FRAP) in live parasites, which revealed rapid fluorescence recovery, supporting their liquid-like behaviour. In conclusion, our study demonstrates the role of PfHP1 mediated LLPS in formation of heterochromatin and var gene silencing; unveiling a fundamental mechanism that drives antigenic variation in P. Falciparum.
2026-02-16 | GSE300368 | GEO
Project description:Malaria caused by Plasmodium falciparum involves antigenic variation on the infected red blood cells through mutually exclusive expression of var genes. The repressed var genes have a distinct genome organization where they localize as a cluster near the nuclear periphery and are bound by PfHP1 (P. falciparum Heterochromatin Protein 1). However, the mode of regulation of var genes by PfHP1 remains unclear. In this study, we show that PfHP1 undergoes liquid-liquid phase separation (LLPS) in vitro in an RNA and DNA-dependent manner. Single-molecule DNA tethering experiments further revealed that AT-rich DNA sequences act as nucleation sites for the assembly and compaction of PfHP1-mediated heterochromatinization. We have also identified point mutations in the IDRs (intrinsically disordered regions) of PfHP1 that disrupt its phase separation as well as DNA compaction in vitro. An ectopic expression of PfHP1 phase separation and DNA compaction mutants led to dispersed nuclear localization, in contrast to the punctate appearance of the wild-type protein and altered chromatin binding at var genes. These results were corroborated with DiCre/loxP based conditional expression of the same PfHP1 mutants, which also led to the de-repression of multiple var genes (as many as 54 out of 60 var genes), mimicking the phenotype of PfHP1 depletion mutants. To assess the dynamic properties of PfHP1 condensates in vivo, we performed fluorescence recovery after photobleaching (FRAP) in live parasites, which revealed rapid fluorescence recovery, supporting their liquid-like behaviour. In conclusion, our study demonstrates the role of PfHP1 mediated LLPS in formation of heterochromatin and var gene silencing; unveiling a fundamental mechanism that drives antigenic variation in P. Falciparum.
2026-02-16 | GSE300206 | GEO
Project description:Malaria caused by Plasmodium falciparum involves antigenic variation on the infected red blood cells through mutually exclusive expression of var genes. The repressed var genes have a distinct genome organization where they localize as a cluster near the nuclear periphery and are bound by PfHP1 (P. falciparum Heterochromatin Protein 1). However, the mode of regulation of var genes by PfHP1 remains unclear. In this study, we show that PfHP1 undergoes liquid-liquid phase separation (LLPS) in vitro in an RNA and DNA-dependent manner. Single-molecule DNA tethering experiments further revealed that AT-rich DNA sequences act as nucleation sites for the assembly and compaction of PfHP1-mediated heterochromatinization. We have also identified point mutations in the IDRs (intrinsically disordered regions) of PfHP1 that disrupt its phase separation as well as DNA compaction in vitro. An ectopic expression of PfHP1 phase separation and DNA compaction mutants led to dispersed nuclear localization, in contrast to the punctate appearance of the wild-type protein and altered chromatin binding at var genes. These results were corroborated with DiCre/loxP based conditional expression of the same PfHP1 mutants, which also led to the de-repression of multiple var genes (as many as 54 out of 60 var genes), mimicking the phenotype of PfHP1 depletion mutants. To assess the dynamic properties of PfHP1 condensates in vivo, we performed fluorescence recovery after photobleaching (FRAP) in live parasites, which revealed rapid fluorescence recovery, supporting their liquid-like behaviour. In conclusion, our study demonstrates the role of PfHP1 mediated LLPS in formation of heterochromatin and var gene silencing; unveiling a fundamental mechanism that drives antigenic variation in P. falciparum.
2026-02-16 | GSE299944 | GEO