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: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 “ring-like” and less “trophozoite-like”, 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.

Project description:Artemisinin (ART)-resistant Plasmodium falciparum (Pf) threatens global malaria control. Resistance, driven by mutations in Pfk13, is multifaceted but quiescence plays a central role. Epigenetic regulation may contribute, given that only a percentage of parasites survive a pulse of the active drug metabolite dihydroartemisinin (DHA). The identities or roles of these epigenetic factors, however, have yet to be identified. tRNA modifications are a conserved epigenetic translational control mechanism, whereby cellular stress leads to modification reprogramming and codon-biased translation. Here we use liquid chromatography-mass spectrometry to profile tRNA modifications in ring-stage ART-sensitive (ART-S) Dd2 and ART-resistant (ART-R) Dd2PfK13_R539T before and after drug pulse. ART-R parasites differentially reprogram their tRNA modification profiles in response to DHA, specifically by mcm5s2U hypomodification of tRNAs. Proteomic and subsequent codon usage analysis revealed that the ART-R parasite proteome displays codon bias, uncovering a new layer of proteomic regulation in drug-resistant parasites. A subset of these proteins were not transcriptionally regulated, suggesting codon-bias translation. Upregulated proteins were enriched for LysAAA, HisCAT and AspGAT and downregulated proteins were enriched for their cognate codons (LysAAG, HisCAC and AspGAC). PfK13 and its interacting partner BIP were among the codon-controlled upregulated proteins. Interestingly, mcm5s2U occurs on the U34 of LysAAA/AAG codons to regulate translational fidelity, providing a mechanistic link between tRNA modification and proteomic data. Transcriptomics revealed enrichment of wobble-base tRNA modification in ART-R parasites post-ART treatment. An anhydrotetracycline-regulated conditional knockdown (cKD) of the terminal s2U methyltransferase, PfMnmA, displayed increased ART survival, signifying that hypomodification plays a critical role in the ART-R parasite response to DHA. cKD parasites also had altered responses to proteotoxic and mitochondrial antimalarials, uncovering overlaps between epigenetic stress response pathways. This work describes a novel epigenetic pathway via tRNA s2U reprogramming that ART-R parasites may use to help survive ART-induced stress.

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Plasmodium parasites mount an arrest response against dihydroartemisinin [P. falciparum RNA-Seq]

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