Unknown,Transcriptomics,Genomics,Proteomics

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Expression data from TSA-treated Plasmodium

ABSTRACT: 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.

ORGANISM(S): Plasmodium falciparum

SUBMITTER: Elizabeth Winzeler

PROVIDER: E-GEOD-41567 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Control of malaria is threatened by emerging parasite resistance to artemisinin drug (ART) therapies. The molecular details of how Plasmodium malaria parasites response to ART and how this relates to resistance is not clear. To determine how parasites respond to ART by altering gene expression, we performed a transcriptomic study of dihydroartemisinin (DHA) response in P. falciparum K1 strain and in P. berghei ANKA strain. Microarray data from DHA-treated P. falciparum trophozoite stage parasites were compared with data from other ART treatments. Genes with consistent changes in expression were identified, which includes notably down-regulation of cytosolic ribosomal protein genes. RNA-seq data revealed a similar pattern of transcriptomic change, although the pattern was much clearer in that more than one-third of P. falciparum trophozoite genes are differentially expressed with greater statistical support for down-regulation of ribosomal protein genes. The poor overlap of differentially-expressed genes between microarray and RNA-seq and less-well defined patterns for the former suggests that the accuracy of microarray is limited by technological bias. The trophozoite response to DHA is overall âring-likeâ and less âtrophozoite-likeâ, which is consistent with previous findings that Plasmodium can enter a quiescent ring-like state to resist ART. RNA-seq data from DHA-treated P. falciparum rings reveal a more muted response, although there is considerable overlap of differentially expressed genes with DHA-treated trophozoites. In contrast, P. falciparum schizonts are unresponsive to DHA, suggesting that the protective response acts mainly to arrest parasite development through the G2/M checkpoint. The transcriptional response of P. berghei to DHA treatment in vivo in infected mice is strikingly similar to the P. falciparum in vitro ring and trophozoite responses, in which ribosomal protein genes are notably down-regulated. These results suggest Plasmodium species respond to DHA in the same way. This knowledge could be applied to outwit the parasite to deliver more effective artemisinin therapies, and maybe hinder the development of drug resistance. Two condition drug-treatment experiment, Dihydroartemisinin vs. Vehicle control treatment with matched reference untreated controls. Biological replicates: 5 independently grown and harvested experimental culture replicates. One replicate of treatment/reference time-point per array.

Project description:For malaria transmission, the parasite must undergo sexual differentiation into mature gametocytes. However, the molecular basis for this critical transition in the parasites life cycle is unknown. Six previously uncharacterized genes, Pfg14.744, Pfg14.745, Pfg14.748, Pfg14.763, Pfg14.752 and Pfg6.6 that are members of a 36 gene Plasmodium falciparum-specific subtelomeric superfamily were found to be expressed in parasites that are committed to sexual development as suggested by co-expression of Pfs16 and Pfg27. Northern blots demonstrated that Pfg14.744 and Pfg14.748 were first expressed before the parasites differentiated into morphologically distinct gametocytes, transcription continued to increase until stage II gametocytes were formed and then rapidly decreased. Immunofluorescence assays indicated that both proteins were only produced in the subpopulation of ring stage parasites that are committed to gametocytogenesis and both localized to the parasitophorous vacuole (PV)b of the early ring stage parasites. As the parasites continued to develop Pfg14.748 remained within the parasitophorous vacuole, while Pfg14.744 was detected in the erythrocyte. The 5' flanking region of either gene alone was sufficient to drive early gametocyte specific expression of green fluorescent protein (GFP). In parasites transfected with a plasmid containing the Pfg14.748 5' flanking region immediately upstream of GFP, fluorescence was observed in a small number of schizonts the cycle before stage I gametocytes were observed. This expression pattern is consistent with commitment to sexual differentiation prior to merozoite release and erythrocyte invasion. Further investigation into the role of these genes in the transition from asexual to sexual differentiation could provide new strategies to block malaria transmission. Microarray analysis was used to compare two clones derived from Plasmodium falciparum strain 3D7 parasites that differ in their ability to undergo gametocytogenesis. Clone G+ produces gametocytes and clone G- produces very few if any gametocytes. RNA was harvested from the cultures when the asexual parasitemia was 0.9-1.48% (day 4) (n=4) after setting up the gametocyte cultures and 5.2-5.58% (day 6) (n=4) prior to the appearance of morphologically distinct gametocytes and used to generate cDNA that was labeled with Cy3 or Cy5 and hybridized to the Plasmodium falciparum 70 mer oligonucleotide microarray developed by DeRisi and co-workers.

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Expression data from TSA-treated Plasmodium

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