The transcription factor AP2XI-2 is a key negative regulator of Toxoplasma gondii merogony
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ABSTRACT:
SUBMITTER: Wang J
PROVIDER: S-EPMC10817966 | biostudies-literature | 2024 Jan
REPOSITORIES: biostudies-literature
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Project description:Commitment to and completion of sexual development are essential for Toxoplasma gondii to produce oocysts in the intestine of the feline host. Understanding of the molecular mechanism responsible for sexual commitment is extremely limited due to the lack of model systems. Here, we show that the transcription factors AP2XI-2 and AP2XII-1 associated with the epigenetic repressors MORC/HDAC3 complex are constitutively expressed in both tachyzoite and bradyzoite stages but not in the merozoite stage. Depletion of AP2XI-2 or AP2XII-1 elicits the expression of genes specific to merozoites, but they play different roles in the merogony process. Depletion of AP2XI-2 in type II Pru strain induced parasites to undergo merogony and produce mature merozoites in alkaline medium but not in neutral medium, whereas the AP2XII-1 depleted Pru strain underwent several rounds of schizogony and produced merozoites in neutral medium and more markedly under alkaline conditions. Furthermore, we show that two AP2XI-2 interacting proteins are also involved in repressing merozoite programming. Overall, these findings indicate that the merozoite primed pre-sexual commitment is controlled by an intricate regulatory network and that AP2XI-2 or AP2XII-1 depleted parasites can be used as a model to study the merogony in vitro.
2023-12-19 | GSE248448 | GEO
Project description:Commitment to and completion of sexual development are essential for Toxoplasma gondii to produce oocysts in the intestine of the feline host. Understanding of the molecular mechanism responsible for sexual commitment is extremely limited due to the lack of model systems. Here, we show that the transcription factors AP2XI-2 and AP2XII-1 associated with the epigenetic repressors MORC/HDAC3 complex are constitutively expressed in both tachyzoite and bradyzoite stages but not in the merozoite stage. Depletion of AP2XI-2 or AP2XII-1 elicits the expression of genes specific to merozoites, but they play different roles in the merogony process. Depletion of AP2XI-2 in type II Pru strain induced parasites to undergo merogony and produce mature merozoites in alkaline medium but not in neutral medium, whereas the AP2XII-1 depleted Pru strain underwent several rounds of schizogony and produced merozoites in neutral medium and more markedly under alkaline conditions. Furthermore, we show that two AP2XI-2 interacting proteins are also involved in repressing merozoite programming. Overall, these findings indicate that the merozoite primed pre-sexual commitment is controlled by an intricate regulatory network and that AP2XI-2 or AP2XII-1 depleted parasites can be used as a model to study the merogony in vitro.
2023-12-20 | PXD043808 | Pride
Project description:The transcription factor AP2XI-2 is a key negative regulator of Toxoplasma gondii merogony
| PRJNA1044037 | ENA
Project description:The apicomplexan parasite Toxoplasma gondii can infect humans and almost all warm-blooded animals worldwide, poses significant threat to the public health and of veterinary importance. The acute infection was characterized by fast replication of tachyzoites inside the host cells. During this fast amplification process, the gene expression is highly regulated by series of regulator networks. The G1 phase is usually conserved across species and responsible for the preparation of materials for the next replication cell cycle, but seldom regulators were identified in this stage. Here, we functionally characterized the C/G1 phase expressed ApiAP2 transcription factor TgAP2XII-8 in T. gondii tachyzoite. Conditionally knockdown of TgAP2XII-8 leads to significant growth defects and asexual division disorder. Additionally, the parasite cell cycle progression was also disrupted after TgAP2XII-8 depletion, which is characterized by G1 phase arrest. RNA-seq and CUT&Tag experiments revealed that TgAP2XII-8 played as an activator for the ribosomal proteins expressed in G1 phase. Moreover, TgAP2XII-8 bind to a specific DNA motif ([T/C]GCATGCA), which is abundant and conserved in the intergenic region of several other apicomplexans, which may suggest a broad and conserved role for this ApiAP2 in the Phylum of Apicomplexa. These data provide important knowledge for the understanding of transcriptional regulation of parasite cell cycle in T. gondii.
2024-08-25 | GSE275112 | GEO
Project description:Apicomplexan parasites have evolved efficient and distinctive strategies for intracellular replication where the timing of emergence of the daughter cells (budding) is a decisive element. However, the molecular mechanisms that provide the proper timing of parasite budding remain unknown. Using Toxoplasma gondii as a model Apicomplexan, we identified a master regulator that controls the timing of the budding process. We show that an ApiAP2 transcription factor, TgAP2IX-5, controls cell cycle events downstream of centrosome duplication. TgAP2IX-5 binds to the promoter of hundreds of genes and controls the activation of the budding-specific cell cycle expression program. TgAP2IX-5 regulates the expression of specific transcription factors that are necessary for the completion of the budding cycle. Moreover, TgAP2IX-5 acts as a limiting factor that ensures that asexual proliferation continues by promoting the inhibition of the differentiation pathway. Therefore, TgAP2IX-5 is a master regulator that controls both cell cycle and developmental pathways.
| S-EPMC7791101 | biostudies-literature
Project description:Differentiation of the protozoan parasite Toxoplasma gondii into its latent bradyzoite stage is a key event in the parasite's life cycle. Compound 2 is an imidazopyridine that was previously shown to inhibit the parasite lytic cycle, in part through inhibition of parasite cGMP-dependent protein kinase. We show here that Compound 2 can also enhance parasite differentiation, and we use yeast three-hybrid analysis to identify TgBRADIN/GRA24 as a parasite protein that interacts directly or indirectly with the compound. Disruption of the TgBRADIN/GRA24 gene leads to enhanced differentiation of the parasite, and the TgBRADIN/GRA24 knockout parasites show decreased susceptibility to the differentiation-enhancing effects of Compound 2. This study represents the first use of yeast three-hybrid analysis to study small-molecule mechanism of action in any pathogenic microorganism, and it identifies a previously unrecognized inhibitor of differentiation in T. gondii. A better understanding of the proteins and mechanisms regulating T. gondii differentiation will enable new approaches to preventing the establishment of chronic infection in this important human pathogen.
| S-EPMC4366382 | biostudies-literature
Project description:A transition from the asexual to sexual development in the widespread intracellular pathogen Toxoplasma gondii requires stage switching in its feline (definitive) host, but the mechanisms governing this process remain elusive. Here, we demonstrate a novel apicomplexan-specific transcription factor, TgAP2XII-1, that controls the transition of the acutely infectious tachyzoite stage to a presexual merozoite stage. The AP2XII-1 deletion mutants are elongated and replicate as merozoites by endopolygeny instead of endodyogeny, by which tachyzoites proliferate. Besides, the parasites lacking AP2XII-1 show a merozoite-type transcriptional profile. Indeed, AP2XII-1 directly targets many stage-specific genes via its interaction with the MORC complex, eventually repressing a repertoire of sex-related transcripts in tachyzoites. In conclusion, our work identifies AP2XII-1 as a merogony repressor, provides insight into the sexual commitment of T. gondii, and opens a gateway to culture the presexual stages of a model parasitic protist. IMPORTANCE Sexual development is vital for the transmission, genetic hybridization, and population evolution of apicomplexan pathogens, which include several clinically relevant parasites, such as Plasmodium, Eimeria, and Toxoplasma gondii. Previous studies have demonstrated different morphological characteristics and division patterns between asexual and sexual stages of the parasites. However, the primary regulation is poorly understood. A transition from the asexual to the sexual stage is supposedly triggered/accompanied by rewiring of gene expression and controlled by transcription factors and chromatin modulators. Herein, we discovered a tachyzoite-specific transcriptional factor AP2XII-1, which represses the presexual development in the asexual tachyzoite stage of T. gondii. Conditional knockdown of AP2XII-1 perturbs tachyzoite proliferation by endodyogeny and drives a transition to a morphologically and transcriptionally distinct merozoite stage. The results also suggest a hierarchical transcriptional regulation of sexual development by AP2 factors and provide a path to culturing merozoites and controlling inter-host transmission of T. gondii.
| S-EPMC10653792 | biostudies-literature
Project description:Apicomplexan parasites, including Toxoplasma gondii, encode many plant-like proteins, which play significant roles and present attractive targets for drug development. In this study, we have characterized the plant-like protein phosphatase PPKL, which is unique to the parasite and absent in its mammalian host. We have shown that its localization changes as the parasite divides. In non-dividing parasites, it is present in the cytoplasm, nucleus, and preconoidal region. As the parasite begins division, PPKL is enriched in the preconoidal region and the cortical cytoskeleton of nascent parasites. Later in the division, PPKL is present in the basal complex ring. Conditional knockdown of PPKL showed that it is essential for parasite propagation. Moreover, parasites lacking PPKL exhibit uncoupling of division, with normal DNA duplication but severe defects in forming daughter parasites. While PPKL depletion does not impair the duplication of centrosomes, it affects the stability of cortical microtubules. Both co-immunoprecipitation and proximity labeling identified the kinase DYRK1 as a potential functional partner of PPKL. Complete knockout of DYRK1 causes parasites to exhibit division defects with predominantly asynchronous divisions. Global phosphoproteomics analysis revealed a significant increase in phosphorylation of the microtubule-associated protein SPM1 in PPKL-depleted parasites, suggesting that PPKL regulates cortical microtubules by mediating the phosphorylation state of SPM1. More importantly, the phosphorylation of cell cycle-associated kinase Crk1, a known regulator of daughter cell assembly, is altered in PPKL-depleted parasites. Thus, we propose that PPKL regulates daughter parasite development by influencing the Crk1-dependent signaling pathway. IMPORTANCE Toxoplasma gondii can cause severe disease in immunocompromised or immunosuppressed patients and during congenital infections. Treating toxoplasmosis presents enormous challenges since the parasite shares many biological processes with its mammalian hosts, which results in significant side effects with current therapies. Consequently, proteins that are essential and unique to the parasite represent favorable targets for drug development. Interestingly, Toxoplasma, like other members of the phylum Apicomplexa, has numerous plant-like proteins, many of which play crucial roles and do not have equivalents in the mammalian host. In this study, we found that the plant-like protein phosphatase PPKL appears to be a key regulator of daughter parasite development. With the depletion of PPKL, the parasite shows severe defects in forming daughter parasites. This study provides novel insights into the understanding of parasite division and offers a new potential target for the development of antiparasitic drugs.
| S-EPMC10746186 | biostudies-literature
Project description:Apicomplexan parasites, including Toxoplasma gondii, encode many plant-like proteins, which play significant roles and present attractive targets for drug development. In this study, we have characterized the plant-like protein phosphatase PPKL, which is unique to the parasite and absent in its mammalian host. We have shown that its localization changes as the parasite divides. In non-dividing parasites, it is present in the cytoplasm, nucleus, and preconoidal region. As the parasite begins division, PPKL is enriched in the preconoidal region and the cortical cytoskeleton of the nascent parasites. Later in the division, PPKL is present in the basal complex ring. Conditional knockdown of PPKL showed that it is essential for parasite propagation. Moreover, parasites lacking PPKL exhibit uncoupling of division, with normal DNA duplication but severe defects in forming daughter parasites. While PPKL depletion does not impair the duplication of centrosomes, it affects the rigidity and arrangement of the cortical microtubules. Both Co-Immunoprecipitation and proximity labeling identified the kinase DYRK1 as a potential functional partner of PPKL. Complete knockout of DYRK1 phenocopies lack of PPKL, strongly suggesting a functional relationship between these two signaling proteins. Global phosphoproteomics analysis revealed a significant increase in phosphorylation of the microtubule-associated proteins SPM1 in PPKL-depleted parasites, suggesting PPKL regulates the cortical microtubules by mediating the phosphorylation state of SPM1. More importantly, the phosphorylation of cell cycle-associated kinase Crk1, a known regulator of daughter cell assembly, is altered in PPKL-depleted parasites. Thus, we propose that PPKL regulates daughter parasite development by influencing the Crk1-dependent signaling pathway.
| S-EPMC10312731 | biostudies-literature
Project description:IFN-γ orchestrates cell-autonomous host defense against various intracellular vacuolar pathogens. IFN-γ-inducible GTPases, such as p47 immunity-related GTPases (IRGs) and p65 guanylate-binding proteins (GBPs), are recruited to pathogen-containing vacuoles, which is important for disruption of the vacuoles, culminating in the cell-autonomous clearance. Although the positive regulation for the proper recruitment of IRGs and GBPs to the vacuoles has been elucidated, the suppressive mechanism is unclear. Here, we show that Rab GDP dissociation inhibitor α (RabGDIα), originally identified as a Rab small GTPase inhibitor, is a negative regulator of IFN-γ-inducible GTPases in cell-autonomous immunity to the intracellular pathogen Toxoplasma gondii. Overexpression of RabGDIα, but not of RabGDIβ, impaired IFN-γ-dependent reduction of T. gondii numbers. Conversely, RabGDIα deletion in macrophages and fibroblasts enhanced the IFN-γ-induced clearance of T. gondii. Furthermore, upon a high dose of infection by T. gondii, RabGDIα-deficient mice exhibited a decreased parasite burden in the brain and increased resistance in the chronic phase than did control mice. Among members of IRGs and GBPs important for the parasite clearance, Irga6 and Gbp2 alone were more frequently recruited to T. gondii-forming parasitophorous vacuoles in RabGDIα-deficient cells. Notably, Gbp2 positively controlled Irga6 recruitment that was inhibited by direct and specific interactions of RabGDIα with Gbp2 through the lipid-binding pocket. Taken together, our results suggest that RabGDIα inhibits host defense against T. gondii by negatively regulating the Gbp2-Irga6 axis of IFN-γ-dependent cell-autonomous immunity.
| S-EPMC4547277 | biostudies-literature