Global Transcriptional Repression: Initial and Essential Step for Plasmodium Sexual Development
Ontology highlight
ABSTRACT:
ORGANISM(S): Plasmodium berghei ANKA
PROVIDER: GSE66190 | GEO | 2015/10/01
SECONDARY ACCESSION(S): PRJNA276081
REPOSITORIES: GEO
Similar Datasets
Project description:Gametocytes are nonreplicative sexual forms that mediate malaria transmission to a mosquito vector. They are generated from asexual blood-stage parasites that proliferate in the circulation. However, little is known about how this transition is genetically regulated. Here, we report that an Apetala2 (AP2) family transcription factor, AP2-G2, regulates this transition as a transcriptional repressor. Disruption of AP2-G2 in the rodent malaria parasite Plasmodium berghei did not prevent commitment to the sexual stage but did halt development before the appearance of sex-specific morphologies. ChIP-seq analysis revealed that AP2-G2 targeted ?1,500 genes and recognized a five-base motif in their promoters. Most of these target genes are required for asexual proliferation of the parasites in the blood, suggesting that AP2-G2 blocks the program that precedes asexual replication to promote conversion to the sexual stage. Microarray analysis showed that the identified targets constituted ?70% of the up-regulated genes in AP2-G2-depleted parasites, suggesting that AP2-G2 actually functions as a repressor in gametocytes. A promoter assay using a centromere plasmid demonstrated that the binding motif functions as a cis-acting negative regulatory element. These results suggest that global transcriptional repression, which occurs during the initial phase of gametocytogenesis, is an essential step in Plasmodium sexual development.
| S-EPMC4611670 | biostudies-literature
Project description:Gametocytes are nonreplicative sexual forms that mediate malaria transmission to a mosquito vector. They are generated from asexual blood stage parasites, which proliferate in the circulation. However, it remains largely unknown as to how this transition is genetically regulated. Here, we report that an Apetala2 (AP2) family transcription factor, AP2-G2, regulates the transition as a transcriptional repressor. Disruption of AP2-G2 in the rodent malaria parasites, Plasmodium berghei, did not prevent commitment to the sexual stage but halted their development before manifesting sex-specific morphologies. ChIP-seq analysis revealed that AP2-G2 targets approximately 1,500 genes and recognizes a five-base motif on their promoters. Most of these target genes are required for asexual proliferation in the blood by the parasites, thereby suggesting that AP2-G2 blocks the program for asexual replication of parasites in the blood. DNA microarray analysis showed that the identified targets constituted approximately 70% of the upregulated genes in AP2-G2-depleted parasites, and a promoter assay using a centromere plasmid demonstrated that the binding motif functions as a cis-acting negative regulatory element. These results suggest that global transcriptional repression, which occurs during the initial phase of gametocytogenesis, is an essential step to promote conversion to the sexual stage.
2015-10-01 | GSE66188 | GEO
Project description:Gametocytes are nonreplicative sexual forms that mediate malaria transmission to a mosquito vector. They are generated from asexual blood stage parasites, which proliferate in the circulation. However, it remains largely unknown as to how this transition is genetically regulated. Here, we report that an Apetala2 (AP2) family transcription factor, AP2-G2, regulates the transition as a transcriptional repressor. Disruption of AP2-G2 in the rodent malaria parasites, Plasmodium berghei, did not prevent commitment to the sexual stage but halted their development before manifesting sex-specific morphologies. ChIP-seq analysis revealed that AP2-G2 targets approximately 1,500 genes and recognizes a five-base motif on their promoters. Most of these target genes are required for asexual proliferation in the blood by the parasites, thereby suggesting that AP2-G2 blocks the program for asexual replication of parasites in the blood. DNA microarray analysis showed that the identified targets constituted approximately 70% of the upregulated genes in AP2-G2-depleted parasites, and a promoter assay using a centromere plasmid demonstrated that the binding motif functions as a cis-acting negative regulatory element. These results suggest that global transcriptional repression, which occurs during the initial phase of gametocytogenesis, is an essential step to promote conversion to the sexual stage.
2015-10-01 | GSE66189 | GEO
Project description:Gametocytogenesis, the process by which malaria parasites produce sexual forms that can infect mosquitoes, is essential for the transmission of malaria. A transcriptional switch of the pfap2-g gene triggers sexual commitment, but how the complex multi-step process is precisely programed remains largely unknown. Here, by systematic functional screening of a panel of ApiAP2 transcription factors, we identify six new ApiAP2 members associated with gametocytogenesis in Plasmodium falciparum. Among these, PfAP2-G5 (PF3D7_1139300) was found to be indispensable for gametocytogenesis. This factor suppresses the transcriptional activity of the pfap2-g gene via binding to both the upstream region and exonic gene body, the latter is linked to the maintenance of local heterochromatin structure, thereby preventing initiation of sexual commitment. Removal of this repressive effect through pfap2-g5 knockout disrupts the asexual replication cycle and promotes sexual commitment accompanied by upregulation of pfap2-g expression. However, the gametocytes produced fail to mature fully. Further analyses show that PfAP2-G5 is essential for gametocyte maturation, and causes the down-regulation of pfap2-g and a set of early gametocyte genes activated by PfAP2-G prior to gametocyte development. Collectively, our findings reveal a regulation cascade of gametocyte production in malaria parasites, and provide a new target for transmission blocking interventions.
| S-EPMC8450074 | biostudies-literature
Project description:Translational repression of messenger RNAs (mRNAs) plays an important role in sexual differentiation and gametogenesis in multicellular eukaryotes. Translational repression and mRNA turnover were shown to influence stage-specific gene expression in the protozoan Plasmodium. The DDX6-class RNA helicase, DOZI (development of zygote inhibited), is found in a complex with mRNA species in cytoplasmic bodies of female, blood-stage gametocytes. These translationally repressed complexes are normally stored for translation after fertilization. Genetic disruption of pbdozi inhibits the formation of the ribonucleoprotein complexes, and instead, at least 370 transcripts are diverted to a degradation pathway.
| S-EPMC1609190 | biostudies-literature
Project description:Translational repression of messenger RNAs (mRNAs) plays an important role in sexual differentiation and gametogenesis in multicellular eukaryotes. Translational repression and mRNA turnover were shown to influence stage-specific gene expression in the protozoan Plasmodium. The DDX6-class RNA helicase, DOZI (development of zygote inhibited), is found in a complex with mRNA species in cytoplasmic bodies of female, blood-stage gametocytes. These translationally repressed complexes are normally stored for translation after fertilization. Genetic disruption of pbdozi inhibits the formation of the ribonucleoprotein complexes, and instead, at least 370 transcripts are diverted to a degradation pathway. Keywords: P. berghei, gene expression
2006-09-22 | GSE5889 | GEO
Project description:The Nczf gene has been identified as one of Ncx target genes and encodes a novel KRAB zinc-finger protein, which functions as a sequence specific transcriptional repressor. In order to elucidate Nczf functions, we generated Nczf knockout (Nczf-/-) mice. Nczf-/- mice died around embryonic day 8.5 (E8.5) with small body size and impairment of axial rotation. Histopathological analysis revealed that the cell number decreased and pyknotic cells were occasionally observed. We examined the expression of cell cycle related genes in Nczf-/- mice. p27 expression was increased in E8.0 Nczf-/- mice compared to that of wild type mice. Nczf knockdown by siRNA resulted in increased expression of p27 in mouse embryonic fibroblasts (MEFs). Furthermore, p27 promoter luciferase reporter gene analysis confirmed the regulation of p27 mRNA expression by Nczf. Nczf-/-; p27-/- double knockout mice survived until E11.5 and the defect of axial rotation was restored. These data suggest that p27 repression by Nczf is essential in the developing embryo.
| S-EPMC4872541 | biostudies-literature
Project description:Human to vector transmission of malaria requires that some blood-stage parasites abandon asexual growth and convert into non-replicating sexual forms called gametocytes. The initial steps of gametocytogenesis remain largely uncharacterized. Here, we study this part of the malaria life cycle in Plasmodium falciparum using PfAP2-G, the master regulator of sexual conversion, as a marker of commitment. We demonstrate the existence of PfAP2-G-positive sexually committed parasite stages that precede the previously known committed schizont stage. We also found that sexual conversion can occur by two different routes: the previously described route in which PfAP2-G-expressing parasites complete a replicative cycle as committed forms before converting into gametocytes upon re-invasion, or a direct route with conversion within the same cycle as initial PfAP2-G expression. The latter route is linked to early PfAP2-G expression in ring stages. Reanalysis of published single-cell RNA-sequencing (RNA-seq) data confirmed the presence of both routes. Consistent with these results, using plaque assays we observed that, in contrast to the prevailing model, many schizonts produced mixed plaques containing both asexual parasites and gametocytes. Altogether, our results reveal unexpected features of the initial steps of sexual development and extend the current view of this part of the malaria life cycle.
| S-EPMC6294672 | biostudies-literature
Project description:In the malaria parasite Plasmodium falciparum, changes in the distribution of heterochromatin at specific loci regulate the expression of clonally variant genes (CVGs), which play fundamental roles in host-parasite interactions. In addition to differences in heterochromatin between individual parasites associated with variant expression of CVGs, changes in heterochromatin distribution associated with different developmental stages have been described. However, while stage II/III gametocytes (sexual precursors) have an altered distribution of heterochromatin compared with asexual blood stages, it is unclear if heterochromatin changes already occur at the very early stages of sexual development. Here we used a transgenic parasite line in which sexual conversion can be conditionally induced to characterise the changes in heterochromatin distribution associated with the earliest stages of sexual development. We found that there were essentially no changes in sexual rings or stage I gametocytes compared with asexual blood stages, and remodelling of heterochromatin started at stage II or III of gametocyte development, with changes similar to those previously described in parasites of a different genetic background. Therefore, global redistribution of heterochromatin does not appear to play a role in the initial steps of sexual development. We also found that, for several genes, changes in expression associated with sexual development precede changes in the heterochromatin at their locus.
2024-10-09 | GSE252334 | GEO
Project description:The ubiquitous bacterial second messenger c-di-GMP is intensively studied in pathogens but less so in mutualistic bacteria. Here, we report a genome-wide investigation of functional diguanylate cyclases (DGCs) synthesizing c-di-GMP from two molecules of GTP in Sinorhizobium fredii CCBAU45436, a facultative microsymbiont fixing nitrogen in nodules of diverse legumes, including soybean. Among 25 proteins harboring a putative GGDEF domain catalyzing the biosynthesis of c-di-GMP, eight functional DGCs were identified by heterogenous expression in Escherichia coli in a Congo red binding assay. This screening result was further verified by in vitro enzymatic assay with purified full proteins or the GGDEF domains from representative functional and nonfunctional DGCs. In the same in vitro assay, a functional EAL domain catalyzing the degradation of c-di-GMP into pGpG was identified in a protein that has an inactive GGDEF domain but with an active phosphodiesterase (PDE) function. The identified functional DGCs generally exhibited low transcription levels in soybean nodules compared to free-living cultures, as revealed in transcriptomes. An engineered upregulation of a functional DGC in nodules led to a significant increase of c-di-GMP level and symbiotic defects, which were not observed when a functional EAL domain was upregulated at the same level. Further transcriptional analysis and gel shift assay demonstrated that these functional DGCs were all transcriptionally repressed in nodules by a global pleiotropic regulator, MucR1, that is essential in Sinorhizobium-soybean symbiosis. These findings shed novel insights onto the systematic regulation of c-di-GMP biosynthesis in mutualistic symbiosis. IMPORTANCE The ubiquitous second messenger c-di-GMP is well-known for its role in biofilm formation and host adaptation of pathogens, whereas it is less investigated in mutualistic symbioses. Here, we reveal a cocktail of eight functional diguanylate cyclases (DGCs) catalyzing the biosynthesis of c-di-GMP in a broad-host-range Sinorhizobium that can establish nitrogen-fixing nodules on soybean and many other legumes. These functional DGCs are generally transcribed at low levels in soybean nodules compared to free-living conditions. The engineered nodule-specific upregulation of DGC can elevate the c-di-GMP level and cause symbiotic defects, while the upregulation of a phosphodiesterase that quenches c-di-GMP has no detectable symbiotic defects. Moreover, eight functional DGCs located on two different replicons are all directly repressed in nodules by a global silencer, MucR1, that is essential for Sinorhizobium-soybean symbiosis. These findings represent a novel mechanism of a strategic regulation of the c-di-GMP biosynthesis arsenal in prokaryote-eukaryote interactions.
| S-EPMC8546604 | biostudies-literature