Project description:Tetracyclines are effective but slow-acting antimalarial drugs whose mechanism of action remains uncertain. To characterize the antimalarial mechanism of tetracyclines, we evaluated their stage-specific activities, impacts on parasite transcription, and effects on two predicted organelle targets, the apicoplast and the mitochondrion, in cultured Plasmodium falciparum. Antimalarial effects were much greater after two 48-h life cycles than after one cycle, even if the drugs were removed at the end of the first cycle. Doxycycline-treated parasites appeared morphologically normal until late in the second cycle of treatment but failed to develop into merozoites. Doxycycline specifically impaired the expression of apicoplast genes. Apicoplast morphology initially appeared normal in the presence of doxycycline. However, apicoplasts were abnormal in the progeny of doxycycline-treated parasites, as evidenced by a block in apicoplast genome replication, a lack of processing of an apicoplast-targeted protein, and failure to elongate and segregate during schizogeny. Replication of the nuclear and mitochondrial genomes and mitochondrial morphology appeared normal. Our results demonstrate that tetracyclines specifically block expression of the apicoplast genome, resulting in the distribution of nonfunctional apicoplasts into daughter merozoites. The loss of apicoplast function in the progeny of treated parasites leads to a slow but potent antimalarial effect. We analyzed a series of 12 microarrays covering 55 hours of Plasmodium falciparum treated with doxycycline and 12 microarrays covering the same 55 hours with no doxycycline treatment
Project description:Choline analogs represent a novel class of antimalarial compounds with strong potency against drug-sensitive and resistant P. falciparum. Although, these drugs are presumed to target proteins within lipid biosynthesis pathways; their complete mechanism of action and the parasite’s compensatory response remain to be elucidated. We have applied transcriptional profiling to characterize the global response to the choline analog T4 during the P. falciparum intraerythrocytic life cycle Keywords: Trascriptome analysis of Plasmodium falciparum in response to external stimuli using the affymetrix platform GPL3575
Project description:Tetracyclines are effective but slow-acting antimalarial drugs whose mechanism of action remains uncertain. To characterize the antimalarial mechanism of tetracyclines, we evaluated their stage-specific activities, impacts on parasite transcription, and effects on two predicted organelle targets, the apicoplast and the mitochondrion, in cultured Plasmodium falciparum. Antimalarial effects were much greater after two 48-h life cycles than after one cycle, even if the drugs were removed at the end of the first cycle. Doxycycline-treated parasites appeared morphologically normal until late in the second cycle of treatment but failed to develop into merozoites. Doxycycline specifically impaired the expression of apicoplast genes. Apicoplast morphology initially appeared normal in the presence of doxycycline. However, apicoplasts were abnormal in the progeny of doxycycline-treated parasites, as evidenced by a block in apicoplast genome replication, a lack of processing of an apicoplast-targeted protein, and failure to elongate and segregate during schizogeny. Replication of the nuclear and mitochondrial genomes and mitochondrial morphology appeared normal. Our results demonstrate that tetracyclines specifically block expression of the apicoplast genome, resulting in the distribution of nonfunctional apicoplasts into daughter merozoites. The loss of apicoplast function in the progeny of treated parasites leads to a slow but potent antimalarial effect. Keywords: Plasmodium falciparum treated with Doxycycline
Project description:Transcription time course of Plasmodium falciparum parasite asexual blood stage progression in the presence of antimalarial drug CID5750730 (Compound C)
Project description:<p>The emergence of multi-drug resistant Plasmodium falciparum underscores the urgent need for new antimalarial therapies. SC83288, a novel chemical entity, is highly effective against P. falciparum both in vivo and in vitro, including strains resistant to artemisinin and partner drugs. Here, we show that SC83288 disrupts blood-stage development by blocking DNA replication and arresting karyokinesis. We identify the parasite’s DNA and tRNAAsp methyltransferase PfDNMT2 as a primary molecular target, linking drug action to impaired epigenetic regulation, altered S-adenosylmethionine fluxes, and compensatory transcriptional responses. Resistance to SC83288 arises through mutations in the parasite’s SERCA-type Calcium ATPase PfATP6, which enable transport of the compound into the endoplasmic reticulum, away from its nuclear targets. This novel resistance mechanism carries a substantial fitness cost, limiting its potential for spread. Together, target validation, a unique resistance profile, and high fitness cost strengthen SC83288’s potential as a promising clinical development candidate for malaria treatment.</p>
Project description:The increasing spread of drug-resistant malaria strains underscores the need for new antimalarial agents with novel modes of action (MOAs). Here, we describe a compound representative of a new class of antimalarials. This molecule, ACT-213615, potently inhibits in vitro erythrocytic growth of all tested Plasmodium falciparum strains, irrespective of their drug resistance properties, with IC(50) values in the low single-digit nanomolar range. Like the clinically used artemisinins, the compound equally and very rapidly affects all three asexual erythrocytic parasite stages. In contrast, microarray studies suggest that the MOA of ACT-213615 is different from that of the artemisinins and other known antimalarials. ACT-213615 is orally bioavailable in mice, exhibits activity in the murine P. berghei model and efficacy comparable to that of the reference drug chloroquine in the recently established P. falciparum SCID mouse model.ACT-213615 represents a new class of potent antimalarials that merits further investigation for its clinical potential. 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. Trophozoite-stage P. falciparum cells were treated with ACT-213615 for increasing amount of time at IC50 concentration and cells were harvested in parralled with DMSO treated controls for microarray-based transcriptional profiling.
Project description:Due to the recurring loss of antimalarial drugs to resistance, there is a need for novel targets, drugs, and combination therapies to ensure the availability of current and future countermeasures. Pyrazoleamides belong to a novel class of antimalarial drugs that disrupt sodium ion homeostasis, although the exact consequences of this disruption in Plasmodium falciparum remain under investigation. In vitro experiments demonstrated that parasites carrying mutations in the metabolic enzyme PfATP4 develop resistance to pyrazoleamide compounds. However, the underlying mechanisms that allow mutant parasites to evade pyrazoleamide treatment are unclear. Here, we first performed experiments to identify the sublethal dose of a pyrazoleamide compound (PA21A092) that caused an approximately 50% reduction in growth over one intraerythrocytic developmental cycle (IDC). At this drug concentration, we collected transcriptomic and metabolomic data at multiple time points during the IDC to quantify gene- and metabolite-level alterations in the treated parasites. To probe the effects of pyrazoleamide treatment on parasite metabolism, we coupled the time-resolved omics data with a metabolic network model of P. falciparum. We found that the drug-treated parasites adjusted carbohydrate metabolism to enhance synthesis of myoinositol—a precursor for phosphatidylinositol biosynthesis. This metabolic adaptation caused a decrease in metabolite flux through the pentose phosphate pathway, causing a decreased rate of RNA synthesis and an increase in oxidative stress. Our model analyses suggest that downstream consequences of enhanced myoinositol synthesis may underlie adjustments that could lead to resistance emergence in P. falciparum exposed to a sublethal dose of a pyrazoleamide drug.
Project description:The increasing spread of drug-resistant malaria strains underscores the need for new antimalarial agents with novel modes of action (MOAs). Here, we describe a compound representative of a new class of antimalarials. This molecule, ACT-213615, potently inhibits in vitro erythrocytic growth of all tested Plasmodium falciparum strains, irrespective of their drug resistance properties, with IC(50) values in the low single-digit nanomolar range. Like the clinically used artemisinins, the compound equally and very rapidly affects all three asexual erythrocytic parasite stages. In contrast, microarray studies suggest that the MOA of ACT-213615 is different from that of the artemisinins and other known antimalarials. ACT-213615 is orally bioavailable in mice, exhibits activity in the murine P. berghei model and efficacy comparable to that of the reference drug chloroquine in the recently established P. falciparum SCID mouse model.ACT-213615 represents a new class of potent antimalarials that merits further investigation for its clinical potential. 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.
Project description:Malaria infection renders humans more attractive to Anopheles gambiae sensu lato mosquitoes than uninfected people. The mechanisms remain unknown. Here, we show that an isoprenoid precursor produced by Plasmodium falciparum, (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate (HMBPP), affects A. gambiae s.l. blood meal seeking and feeding behaviors, as well as susceptibility to infection. HMBPP acts indirectly by triggering human red blood cells to increase the release of CO2, aldehydes, and monoterpenes, which together enhance vector attraction, and stimulate vector feeding. When offered in a blood meal, HMBPP modulates neural, antimalarial, and oogenic gene transcription without affecting mosquito survival or fecundity, while in a P. falciparum infected blood meal, sporogony is increased.