Transcriptome profiling reveals functional variation in Plasmodium falciparum parasites from controlled human malaria infection studies
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ABSTRACT:
PROVIDER: PRJNA561164 | ENA |
REPOSITORIES: ENA
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Project description:Background 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. Results Following 2h exposure to trichostatin A (TSA), suberoylanilide hydroxamic acid (SAHA) or a 2-aminosuberic acid derivative (2-ASA-9), ~18-28% of genes in P. falciparum trophozoite-stage parasites were regulated greater than two fold. This global induction was transitory, with fewer genes (3-5%) regulated after removing the compounds and culturing for a further 2h. Just nine genes, including alpha-II-tubulin, were up-regulated by all three compounds. Despite structural similarity, the three inhibitors caused quite diverse transcriptional effects, possibly reflecting subtle differences in mode of action or cellular distribution. Conclusions Three structurally related HDAC inhibitors have been found to cause profound, genome-wide, transcriptional changes in P. falciparum parasites, but most effects were transitory. This highlights the dynamic and exquisitely controlled nature of transcription in these malaria parasites. We also identified a small subset of nine genes over-expressed by all three HDAC inhibitors that may represent the first recognized set of transcriptional markers that signify HDAC inhibition in malaria parasites. This data set is an important contribution to our understanding of gene regulation in malaria parasites and supports growing evidence for the potential of HDAC inhibitors as new antimalarial agents.
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Project description:The major virulence factor of Plasmodium falciparum parasites, PfEMP1 is expressed by a multigene family, termed var genes. Here selection linked integration (SLI) was utilized to modify var genes in P. falciparum parasites to select for parasite populations expressing a single var gene. Bulk RNA was isolated from ring stage parasites of these SLI parasite populations and analyzed with next generation sequencing. The proportion of exon 2 transcripts of var genes normalized to transcripts per million was determined per cell line to confirm the predominant expression of the desired var gene.
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Project description:If copy number variants (CNVs) are predominantly deleterious, we would expect them to be more efficiently purged from populations with a large effective population size (Ne) than from populations with a small Ne. Malaria parasites (Plasmodium falciparum) provide an excellent organism to examine this prediction, because this protozoan shows a broad spectrum of population structures within a single species, with large, stable, outbred populations in Africa, small unstable inbred populations in South America and with intermediate population characteristics in South East Asia. We characterized 122 single-clone parasites, without prior laboratory culture, from malaria-infected patients in 7 countries in Africa, SE Asia and S. America using a high density SNP/CNV microarray. We scored 134 high-confidence CNVs across the parasite exome, including 33 deletions and 102 amplifications, which ranged in size from <500bp to 59kb, as well as 10,107 flanking, biallelic SNPs. Overall, CNVs were rare, small and skewed towards low frequency variants, consistent with the deleterious model. Relative to African and SE Asian populations, CNVs were significantly more common in S. America, showed significantly less skew in allele frequencies, and were significantly larger. On this background of low frequency CNV, we also identified several high-frequency CNVs under putative positive selection using an FST outlier analysis. These included known adaptive CNVs containing rh2b and pfmdr1, and several other CNVs (e.g. DNA helicase, and 3 conserved proteins) that require further investigation. Our data are consistent with a significant impact of genetic structure on CNV burden in an important human pathogen.
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