A Novel Plasmodium Falciparum Bromodomain Protein Regulates Invasion Gene Expression
Ontology highlight
ABSTRACT:
ORGANISM(S): Plasmodium falciparum 3D7
SUBMITTER: Michaela Petter
PROVIDER: E-GEOD-64691 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
Similar Datasets
Project description:To study the bromodomain protein PfBDP1 in the malaria parasite P. falciparum, a transgenic parasite line was generated (PfBDP1DD) in which PfBDP1 was tagged with a haemagglutinin tag and a ligand regulatable FKBP destabilization domain that allowed conditional knockdown of PfBDP1 by removal of the stabilizing ligand Shld1 from cultures. Shld1 was removed 30 hours post invasion (hpi) and the cells allowed to reinvade fresh red blood cells. The effects of PfBDP1 knockdown on gene expression were assessed by transcriptional profiling on microarrays over 6 consecutive time points (8 hour intervals) in the intraerythrocytic developmental cycle (IDC). Two condition matched time course experiment, PfBDP1DD ON versus OFF Shld1. Transgenic P. falciparum 3D7 parasites (PfBDP1DD) expressing an endogeneous PfBDP1-HA-DD fusion protein were grown in the presence of 2.5 nM WR99210/500 nM Shld1 (PfBDP1DD_ON) or 2.5 nM WR99210 (PfBDP1DD_OFF). After invasion, RNA was extracted at 6 consectutive time points in 8 hour intervals during the IDC, starting at 4 hpi, and was processed for microarray analysis. Three matched biological replicates were performed for both conditions, independently grown and harvested. Each array represents one RNA sample.
2015-01-07 | E-GEOD-64688 | biostudies-arrayexpress
Project description:Erythrocyte invasion is an essential step in the life cycle of the malaria parasite Plasmodium falciparum that involves specific interactions between host cell receptors and parasite ligands. How the parasite regulates the expression of invasion-related genes is to date largely unknown. Here we show that a novel, parasite-specific bromodomain protein (PfBDP1) binds to chromatin at the transcriptional start site of invasion-related genes and directly controls their expression. Conditional PfBDP1 knockdown causes a dramatic defect in parasite invasion and growth and results in transcriptional down-regulation of multiple invasion-related genes at a time point critical for invasion. This is the first report of a histone binding protein that activates genes in P. falciparum and our data place PfBDP1 in a central position for controlling the coordinated expression of invasion genes. Bromodomains are emerging therapeutic targets and drugs that specifically inhibit PfBDP1 could be an invaluable tool in the effort to eradicate malaria. P. falciparum 3D7 parasites over-expressing PfBDP1-3xHA (3D7/PfBDP1 OE) [PMID: 23181666] were grown in presence of 5μg/ml BSD-S-HCl. The parasite line 3D7/cam [PMID: 22435676.] grown under the same conditions and expressing hDHFR instead of PfBDP1-3xHA from the same promoter was used as control. RNA extracted from these samples at four consecutive time points each was processed for microarray analysis.
2015-01-07 | E-GEOD-64690 | biostudies-arrayexpress
Project description:We described the biological role of a putative zinc finger protein (Plasmodb id: PF3D7_1008600), which plays an important role during the initiation and subsequent progression of gametocytogenesis in P. falciparum. Hence we termed the protein P. falciparum Zinc Finger Protein for Gametocytogenesis (PfZnFP-G). During the asexual intraerythrocyic developmental cycle (IDC), PfZnFP-G levels peak during the schizont stage during which it is localized in the nucleus. During the IDC, PfZnFP-G appears to be stochastically expressed in ~3% parasite population. Deactivation of PfZnFP-G appears to suppress, but not fully inhibit, production of gametocytes and vice versa overproduction of PfZnFP-G stimulates gametocytogenesis. In addition, PfZnFP-G is capable of associating with DNA binding preferentially to intergenic, promoter regions of the genome, and this binding correlates positively with transcription, particularly of other gametocyte specific genes. PfZnFP-G is also expressed in the mid-to-late gametocytes where it is present in the cytoplasm. Overall, these results suggest a dual function of PfZnFP-G in gametocytogenesis including: (i) commitment as a transcription factor and (ii) gametocyte maturation as a putative RNA binding protein. Transgenic 3D7 wild type parasite lines were generated with PfZnFP-G tagged, over-expressed and knocked-out. Transcriptional profiles across the parasite life cycle were generated. Genome occupancy of PfZnFP-G were also investigated and compared to the corresponding transcriptional profiles.
2015-11-24 | E-GEOD-75295 | biostudies-arrayexpress
Project description:The malaria parasite Plasmodium falciparum relies on clonally variant gene expression in order to escape immune recognition and secure continuous proliferation during blood stage infection. Here, we studied the role of heterochromatin protein 1 (HP1), an evolutionary conserved regulator of heritable gene silencing, in the biology of P. falciparum blood stage parasites. We demonstrate that conditional PfHP1 depletion de-represses hundreds of heterochromatic virulence genes and disrupts the elusive mechanism underlying mutually exclusive expression and antigenic variation of PfEMP1. Intriguingly, we also discovered that the PfHP1-dependent regulation of an ApiAP2 transcription factor controls the switch from asexual parasite proliferation to sexual differentiation. This uncovers the first mechanistic insight into the unknown pathway triggering gametocyte conversion and establishes a new concept of HP1-dependent cell fate decision in unicellular eukaryotes. P. falciparum 3D7 parasites expressing endogenous PfHP1-GFP-DD were grown in presence of 4nM WR/625nM Shield-1 (3D7/HP1ON) or 4nM WR (3D7/HP1OFF). RNA extracted from these samples at eleven consecutive time points each was processed for microarray analysis.
2014-07-09 | E-GEOD-53176 | biostudies-arrayexpress
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.
2014-10-16 | E-GEOD-62364 | biostudies-arrayexpress
Project description:The P. falciparum genome is equipped with several subtelomeric gene families that are implicated in parasite virulence and immune evasion. The members of these gene families are uniformly positioned within heterochromatic domains of the genome and are thus subject to variegated expression. The best-studied example is that of the var gene family encoding the major parasite virulence factor P. falciparum erythrocyte membrane protein 1 (PfEMP1). Transcriptional regulation of other subtelomeric gene families and their role in parasite biology is much less understood. Here, we investigated the mode of transcriptional control of var, rif, stevor, phist and pfmc-2tm families by comparative genome-wide transcriptional profiling of transgenic parasite lines. Our results establish a clear functional distinction between var and non-var transcriptional control mechanisms. Unlike var promoters, we find that promoters of non-var families are not silenced by default. Moreover, we show that mutually exclusive transcription is unique to the var gene family. 3D7 wild-type parasites were transfected with constructs carrying eight different promoters that drive expression of the drug-selectable marker hdhfr-gfp. Thereof seven promoters are members of the multigene families upsA var, upsB var, upsC var, rif, stevor, phistb and pfmc-2tm. The cam promoter was used as transfection-based control and also a wild-type 3D7 cell line was included as control. These nine cell lines were subjected to genome-wide transcriptional profiling. Parasites were synchronized to obtain an 8 hour growth window and were harvested at four consecutive timepoints (TP): TP1 (6-14 hours post-invasion (hpi)); TP2 (14-22 hpi); TP3 (22-30 hpi); TP4 (30-38 hpi) to monitor intra- and inter-family specific linkage of multigene family expression.
2011-09-01 | E-GEOD-31829 | biostudies-arrayexpress
Project description:Quantitative studies of the P. falciparum transcriptome have shown that the tightly controlled progression of the parasite through the intraerythrocytic developmental cycle (IDC) is accompanied by a continuous gene expression cascade where most expressed genes exhibit a single transcriptional peak. Since proteins represent the decisive business end of gene expression, understanding the correlation between mRNA and protein levels is crucial for inferring biological activity from transcriptional gene expression data. While pertinent studies on other organisms show that as little as 20-40% of protein abundance variation may be attributable to corresponding mRNA levels, the situation in Plasmodium is further complicated by the dynamic nature of the cyclic gene expression cascade where the mRNA levels of most genes change constantly during the IDC. In this study, we simultaneously determined mRNA and protein abundance profiles for P. falciparum parasites during the IDC at 2-hour resolution based on spotted oligonucleotide microarrays and 2D-protein gels in combination with DIGE fluorescent dyes. Intriguingly, most proteins are represented by more than one isoform, presumably due to post-translational modifications. Analysis of 366 protein abundance profiles and the corresponding mRNA levels shows that in 67.2% of cases the protein abundance peaks at least 8 hours after the mRNA level peak. While it may be tempting to interpret this as evidence for widespread post-transcriptional gene regulation additional analyses including computer modeling demonstrate that in >60% of these cases the observed protein profiles including the peak lag times could arise as a consequence of the corresponding mRNA levels when simple translation and degradation dynamics are assumed. We further characterize and illustrate these dynamics and show that even human host proteins within the parasite may be subject to similar dynamics as their parasite counterparts. 24 timepoint samples were harvested from a tightly synchronous 6.5 liter biofermenter culture of P. falciparum (Dd2) at 2-hour intervals during one entire intraerythrocytic developmental cycle and compared against a 3D7 RNA reference pool.
2011-06-07 | E-GEOD-24416 | biostudies-arrayexpress
Project description:Drug resistance in Plasmodium falciparum remains a challenge for the malaria eradication programs around the world. With the emergence of artemisinin resistance, the efficacy of the partner drugs in the artemisinin combination therapies (ACT) that include quinoline based drugs is becoming critical. So far only few resistance markers have been identified and verified from which only two ABC transmembrane transporters namely PfMDR1 and PfCRT have been experimentally verified. Another P. falciparum ABC transporter, the multidrug resistance-associated protein (PfMRP2) represents an additional possible factor of drug resistance in P. falciparum. In this study, we identify a parasite clone that is derived from the 3D7 P. falciparum strain and which shows increased resistance to chloroquine and mefloquine through the trophozoite and schizont stages. We demonstrate that the resistance phenotype is caused by a 4.1 kb deletion in the 5M-bM-^@M-^Y upstream region of the pfmrp2 gene that leads to an alteration in the pfmrp2 transcription that result in increased levels of PfMRP2 protein. These results also suggest the importance of putative promoter elements in regulation of gene expression during the P. falciparum intra-erythrocytic developmental cycle and the potential of such genetic polymorphisms to underlie drug resistance phenotypes. Presented here are the data from microarray-based genome-wide transcriptomic and genomic studies of the drug-sensitive and drug-resistant 3D7 clones 11C/wt and 6A/mut. 2 P. falciparum lab clones derived from 3D7 strain were harvested during the intra-erythrocytic cycle at 8hr intervals over 48 hours to obtain a total of 6 time point samples per clone. RNA from a total of 12 samples were extracted. Synthesis of target DNA was carried out as described in Bozdech, Z., S. Mok & A. P. Gupta, (2013) DNA microarray-based genome-wide analyses of Plasmodium parasites. Methods in molecular biology 923: 189-211 and used in replicate microarray hybridizations against a common RNA reference pool of 3D7 strain.
2013-02-07 | E-GEOD-44127 | biostudies-arrayexpress
Project description:Drug resistance in Plasmodium falciparum remains a challenge for the malaria eradication programs around the world. With the emergence of artemisinin resistance, the efficacy of the partner drugs in the artemisinin combination therapies (ACT) that include quinoline based drugs is becoming critical. So far only few resistance markers have been identified and verified from which only two ABC transmembrane transporters namely PfMDR1 and PfCRT have been experimentally verified. Another P. falciparum ABC transporter, the multidrug resistance-associated protein (PfMRP2) represents an additional possible factor of drug resistance in P. falciparum. In this study, we identify a parasite clone that is derived from the 3D7 P. falciparum strain and which shows increased resistance to chloroquine and mefloquine through the trophozoite and schizont stages. We demonstrate that the resistance phenotype is caused by a 4.1 kb deletion in the 5M-bM-^@M-^Y upstream region of the pfmrp2 gene that leads to an alteration in the pfmrp2 transcription that result in increased levels of PfMRP2 protein. These results also suggest the importance of putative promoter elements in regulation of gene expression during the P. falciparum intra-erythrocytic developmental cycle and the potential of such genetic polymorphisms to underlie drug resistance phenotypes. Presented here are the data from microarray-based genome-wide transcriptomic and genomic studies of the drug-sensitive and drug-resistant 3D7 clones 11C/wt and 6A/mut. 2 P. falciparum lab clones derived from 3D7 strain were harvested during the intra-erythrocytic cycle for genomic DNA. gDNA were extracted by phenol chloroform. Synthesis of labelled target DNA was carried out as previously described: Bozdech, Z., M. Llinas, B. L. Pulliam, E. D. Wong, J. Zhu & J. L. DeRisi, (2003) The transcriptome of the intraerythrocytic developmental cycle of Plasmodium falciparum. PLoS Biol 1: E5, and used in comparative genomic microarray hybridizations (CGH).
2013-02-07 | E-GEOD-44128 | biostudies-arrayexpress
Project description:Artemisinin resistance in Plasmodium falciparum, clinically presented as prolonged parasite clearance half-life, has been associated with a mutation in the NLI-interacting factor-like phosphatase PfNIF4, in addition to the mutations in the Kelch13 protein as the major determinant. We found that PfNIF4 predominant expression at the schizont stage and localized in the nuclei of the parasite. To elucidate the functions of PfNIF4 in P. falciparum, we performed PfNIF4 knockdown (KD) using the inducible ribozyme system. PfNIF4 KD attenuated merozoite invasion and affected gametocytogenesis. PfNIF4 KD parasites also showed significantly increased in vitro susceptibility to artemisinins. Transcriptomic analysis revealed that PfNIF4 KD led to significant changes in the expression of approximately 10-25% of parasite genes during the IDC. At the schizont stage, down-regulated genes were significantly enriched in the invasion-related terms, while at the trophozoite and schizont stages, pathways associated with artemisinin resistance (e.g., mitochondrial function, membrane, and Kelch13 interactome) were also down-regulated. Consistent with PfNIF4 being a protein phosphatase, PfNIF4 KD resulted in an overall up-regulation of the phosphoproteome of infected erythrocytes. Specifically, we observed increased phosphorylation of Ser2/5 of the tandem repeats in the Rpb1 C-terminal domain (CTD) of RNA polymerase II (RNAPII) upon PfNIF4 KD. Furthermore, using the TurboID-based proteomic approach, we identified that PfNIF4 interacted with the RNA polymerase II (RNAPII) components, AP2-domain transcription factors, and chromatin-modifiers and binders. These findings suggest that PfNIF4 may act as the RNAPII CTD phosphatase, regulating the expression of general and parasite-specific cellular pathways during the blood-stage development.
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