Early Genomic Amplifications in Blood-Stages of ARMD Plasmodium falciparum Acquiring De Novo Drug Resistance
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ABSTRACT:
ORGANISM(S): Plasmodium falciparum Dd2 Plasmodium falciparum
PROVIDER: GSE35950 | GEO | 2013/05/01
SECONDARY ACCESSION(S): PRJNA151983
REPOSITORIES: GEO
Similar Datasets
Project description:While many molecular changes associated with commonly used antimalarials are known, there remain important questions on how parasites arrive at the correct causal molecular solutions in a haploid genome. We selected for resistance to DSM1, a novel dihydroorotate dehydrogenase (DHODH) inhibitor with a non-biological triazolopyrimidine scaffold, in P. falciparum with the Accelerated Resistance to Multiple Drugs (ARMD) trait. While direct sequencing revealed no mutations in the target DHODH gene, comparative genomic hybridizations from four independently selected DSM1-resistant clones showed a large, single 34-95kb amplification in each clone. Each amplified region always included the DHODH locus. The length of this region and the resulting 2- to 3-fold DHODH copy number increase were verified at the RNA and protein level. DSM1 resistance was stable over several months of in vitro culture. Additional selection at higher DSM1 concentrations caused further gains in CNVs at the DHODH locus. The present system validated DHODH as a key target of the triazolopyrimidine antimalarial, DSM1 and, more importantly, captured large, random CNVs as an early step in the initiation of drug resistance in malaria parasites. This defined system is expected to be valuable for characterizing early, causal molecular steps leading to successful drug resistance
2013-05-01 | GSE35949 | GEO
Project description:This SuperSeries is composed of the SubSeries listed below. Refer to individual Series
2013-05-01 | E-GEOD-35950 | biostudies-arrayexpress
Project description:While many molecular changes associated with commonly used antimalarials are known, there remain important questions on how parasites arrive at the correct causal molecular solutions in a haploid genome. We selected for resistance to DSM1, a novel dihydroorotate dehydrogenase (DHODH) inhibitor with a non-biological triazolopyrimidine scaffold, in P. falciparum with the Accelerated Resistance to Multiple Drugs (ARMD) trait. While direct sequencing revealed no mutations in the target DHODH gene, comparative genomic hybridizations from four independently selected DSM1-resistant clones showed a large, single 34-95kb amplification in each clone. Each amplified region always included the DHODH locus. The length of this region and the resulting 2- to 3-fold DHODH copy number increase were verified at the RNA and protein level. DSM1 resistance was stable over several months of in vitro culture. Additional selection at higher DSM1 concentrations caused further gains in CNVs at the DHODH locus. The present system validated DHODH as a key target of the triazolopyrimidine antimalarial, DSM1 and, more importantly, captured large, random CNVs as an early step in the initiation of drug resistance in malaria parasites. This defined system is expected to be valuable for characterizing early, causal molecular steps leading to successful drug resistance
2013-05-01 | GSE35732 | GEO
Project description:While many molecular changes associated with commonly used antimalarials are known, there remain important questions on how parasites arrive at the correct causal molecular solutions in a haploid genome. We selected for resistance to DSM1, a novel dihydroorotate dehydrogenase (DHODH) inhibitor with a non-biological triazolopyrimidine scaffold, in P. falciparum with the Accelerated Resistance to Multiple Drugs (ARMD) trait. While direct sequencing revealed no mutations in the target DHODH gene, comparative genomic hybridizations from four independently selected DSM1-resistant clones showed a large, single 34-95kb amplification in each clone. Each amplified region always included the DHODH locus. The length of this region and the resulting 2- to 3-fold DHODH copy number increase were verified at the RNA and protein level. DSM1 resistance was stable over several months of in vitro culture. Additional selection at higher DSM1 concentrations caused further gains in CNVs at the DHODH locus. The present system validated DHODH as a key target of the triazolopyrimidine antimalarial, DSM1 and, more importantly, captured large, random CNVs as an early step in the initiation of drug resistance in malaria parasites. This defined system is expected to be valuable for characterizing early, causal molecular steps leading to successful drug resistance RNA from P. falciparum DSM1 resistant cell-line was hybridized against RNA of parental strain, Dd2. DSM1 resistant cell culture was maintained under DSM1 at 333 nM, microarray data were obtained from three hybridizations using RNA from three independent parasite cultures
2013-05-01 | E-GEOD-35949 | biostudies-arrayexpress
Project description:While many molecular changes associated with commonly used antimalarials are known, there remain important questions on how parasites arrive at the correct causal molecular solutions in a haploid genome. We selected for resistance to DSM1, a novel dihydroorotate dehydrogenase (DHODH) inhibitor with a non-biological triazolopyrimidine scaffold, in P. falciparum with the Accelerated Resistance to Multiple Drugs (ARMD) trait. While direct sequencing revealed no mutations in the target DHODH gene, comparative genomic hybridizations from four independently selected DSM1-resistant clones showed a large, single 34-95kb amplification in each clone. Each amplified region always included the DHODH locus. The length of this region and the resulting 2- to 3-fold DHODH copy number increase were verified at the RNA and protein level. DSM1 resistance was stable over several months of in vitro culture. Additional selection at higher DSM1 concentrations caused further gains in CNVs at the DHODH locus. The present system validated DHODH as a key target of the triazolopyrimidine antimalarial, DSM1 and, more importantly, captured large, random CNVs as an early step in the initiation of drug resistance in malaria parasites. This defined system is expected to be valuable for characterizing early, causal molecular steps leading to successful drug resistance gDNA from P. falciparum DSM1 resistant cell-line was hybridized against gDNA of parental strain, Dd2. DSM1 resistant cell culture was maintained under DSM1 at 333 nM, microarray data were obtained from three hybridizations using gDNA from three independent parasite cultures
2013-05-01 | E-GEOD-35732 | biostudies-arrayexpress
Project description:Immunodeficient mouse-human chimeras provide a powerful approach to study host specific pathogens like Plasmodium (P.) falciparum that causes human malaria. Existing mouse models of P. falciparum infection require repeated injections of human red blood cells (RBCs). In addition, clodronate lipsomes and anti-neutrophil antibodies are injected to suppress the clearance of human RBCs by the residual immune system of the immunodeficient mice. Engraftment of NOD-scid Il2rg-/- mice with human hematopoietic stem cells leads to reconstitution of human immune cells. Although human B cell reconstitution is robust and T cell reconstitution is reasonable in the recipient mice, human RBC reconstitution is generally poor or undetectable. The poor reconstitution is mainly the result of a deficiency of appropriate human cytokines that are necessary for the development and maintenance of these cell lineages. Delivery of plasmid DNA encoding human erythropoietin and interleukin-3 into humanized mice by hydrodynamic tail-vein injection resulted in significantly enhanced reconstitution of erythrocytes. With this improved humanized mouse, here we show that P. falciparum infects de novo generated human RBCs, develops into schizonts and causes successive reinvasion. We also show that different parasite strains exhibit variation in their ability to infect these humanized mice. Parasites could be detected by nested PCR in the blood samples of humanized mice infected with P. falciparum K1 and HB3 strains for 3 cycles, whereas in other strains such as 3D7, DD2, 7G8, FCR3 and W2mef parasites could only be detected for 1 cycle. In vivo adaptation of K1 strain further improves the infection efficiency and parasites can be detected by microscopy for 3 cycles. The parasitemia ranges between 0.13 and 0.25% at the first cycle of infection, falls between 0.08 and 0.15% at the second cycle, and drops to barely detectable levels at the third cycle of infection. Compared to existing mouse models, our model generates human RBCs de novo and does not require the treatment of mice with immunomodulators.
| S-EPMC4476714 | biostudies-literature
Project description:In the malaria parasite Plasmodium falciparum, the expression of many genes is regulated by heterochromatin (HC) based on the histone mark tri-methylation of histone H3 lysine 9 (H3K9me3). HC assembly involves three distinct steps: de novo nucleation, spreading and maintenance. Nucleation, which consists in formation of HC in a previously euchromatic region, determines at which specific regions of the genome HC occurs, but this process is not well understood in malaria parasites. Here we investigated the DNA sequence cis determinants of HC nucleation in P. falciparum, using a screening approach based on integration of fragments from different heterochromatic genes into an euchromatic locus, followed by chromatin immunoprecipitation (ChIP). We found that fragments of var gene upstream regions nucleated HC efficiently, whereas fragments from the pfap2-g upstream region or from the mspdbl2 locus did not nucleate HC. Fragments from the beginning of the coding sequence (CDS) of pfap2-g nucleated HC with low efficiency, as evidenced by nucleation requiring long fragments of ~2 kb and occurring only in a fraction of the parasites. These results demonstrate that the primary DNA sequence is a main determinant of HC nucleation in P. falciparum. We also studied HC maintenance at the pfap2-g locus, which demonstrated that specific parts of the upstream region, different from the regions competent for HC nucleation, are required for maintenance. Together, our results provide initial insight into how HC is directed to specific loci and maintained in P. falciparum.
2025-04-07 | GSE287562 | GEO
Project description:BackgroundCopy number variations (CNVs) of the Plasmodium falciparum multidrug resistance 1 (pfmdr1), P. falciparum plasmepsin2 (pfplasmepsin2) and P. falciparum GTP cyclohydrolase 1 (pfgch1) genes are associated with anti-malarial drug resistance in P. falciparum malaria. Droplet digital PCR (ddPCR) assays have been developed for accurate assessment of CNVs in several human genes. The aim of the present study was to develop and validate ddPCR assays for detection of the CNVs of P. falciparum genes associated with resistance to anti-malarial drugs.MethodsA multiplex ddPCR assay was developed to detect the CNVs in the pfmdr1 and pfplasmepsin2 genes, while a duplex ddPCR assay was developed to detect CNV in the pfgch1 gene. The gene copy number (GCN) quantification limit, as well as the accuracy and precision of the ddPCR assays were determined and compared to conventional quantitative PCR (qPCR). In order to reduce the cost of testing, a multiplex ddPCR assay of two target genes, pfmdr1 and pfplasmepsin2, was validated. In addition, the CNVs of genes of field samples collected from Thailand from 2015 to 2019 (n = 84) were assessed by ddPCR and results were compared to qPCR as the reference assay.ResultsThere were no significant differences between the GCN results obtained from uniplex and multiplex ddPCR assays for detection of CNVs in the pfmdr1 and pfplasmepsin2 genes (p = 0.363 and 0.330, respectively). Based on the obtained gene copy number quantification limit, the accuracy and percent relative standard deviation (%RSD) value of the multiplex ddPCR assay were 95% and 5%, respectively, for detection of the CNV of the pfmdr1 gene, and 91% and 5% for detection of the CNV of the pfplasmepsin2 gene. There was no significant difference in gene copy numbers assessed by uniplex or duplex ddPCR assays regarding CNV in the pfgch1 gene (p = 0.276). The accuracy and %RSD value of the duplex ddPCR assay were 95% and 4%, respectively, regarding pfgch1 GCN. In the P. falciparum field samples, pfmdr1 and pfplasmepsin2 GCNs were amplified in 15% and 27% of samples from Ubon Ratchathani, Thailand, while pfgch1 GCN was amplified in 50% of samples from Yala, Thailand. There was 100% agreement between the GCN results obtained from the ddPCR and qPCR assays (κ = 1.00). The results suggested that multiplex ddPCR assay is the optional assay for the accurate detection of gene copy number without requiring calibration standards, while the cost and required time are reduced. Based on the results of this study, criteria for GCN detection by ddPCR analysis were generated.ConclusionsThe developed ddPCR assays are simple, accurate, precise and cost-effective tools for detection of the CNVs in the pfmdr1, pfplasmepsin2 and pfgch1 genes of P. falciparum. The ddPCR assay is a useful additional tool for the surveillance of anti-malarial drug resistance.
| S-EPMC7916280 | biostudies-literature
Project description:Earlier genetic and inhibitor studies showed that epigenetic regulation of gene expression is critical for malaria parasite survival in multiple life stages and a promising target for new antimalarials. We therefore evaluated the activity of 350 diverse epigenetic inhibitors against multiple stages of Plasmodium falciparum We observed ≥90% inhibition at 10 μM for 28% of compounds against asexual blood stages and early gametocytes, of which a third retained ≥90% inhibition at 1 μM.
| S-EPMC7318029 | biostudies-literature
Project description:During the erythrocytic cycle, Plasmodium falciparum is highly dependent on an adequate thiol status for its survival. Glutathione reductase as well as de novo synthesis of GSH are responsible for the maintenance of the intracellular GSH level. The first and rate-limiting step of the synthetic pathway is catalysed by gamma-glutamylcysteine synthetase (gamma-GCS). Using L-buthionine-(S, R)-sulphoximine (BSO), a specific inhibitor of the gamma-GCS, we show that the infection with P. falciparum causes drastic changes in the GSH metabolism of red blood cells (RBCs). Infected RBCs lose GSH at a rate 40-fold higher than non-infected RBCs. The de novo synthesis of the tripeptide was found to be essential for parasite survival. GSH depletion by BSO inhibits the development of P. falciparum with an IC(50) of 73 microM. The effect of the drug is abolished by supplementation with GSH or GSH monoethyl ester. Our studies demonstrate that the plasmodicidal effect of the inhibitor BSO does not depend on its specificity towards its target enzyme in the parasite, but on the changed physiological needs for the metabolite GSH in the P. falciparum-infected RBCs. Therefore the depletion of GSH is proposed as a chemotherapeutic strategy for malaria, and gamma-GCS is proposed as a potential drug target.
| S-EPMC1220884 | biostudies-other