bims-toxgon 2023-04-16 papers

bims-toxgon

Biomed News

on Toxoplasma gondii metabolism

Issue of 2023–04–16
six papers selected by
Lakesh Kumar, BITS Pilani

Unravelling Strain-Specific Modifications of Toxoplasma gondii tRNA and sncRNA Using LC-MS/MS.
Short-term culture adaptation of Toxoplasma gondii archetypal II and III field isolates affects cystogenic capabilities and modifies virulence in mice.
Exploring the epidemiological role of the Eurasian lynx (Lynx lynx) in the life cycle of Toxoplasma gondii.
Tim-3 regulates the immunosuppressive function of decidual MDSCs via the Fyn-STAT3-C/EBPβ pathway during Toxoplasma gondii infection.
Targeting Toxoplasma gondii ME49 TgAPN2: A Bioinformatics Approach for Antiparasitic Drug Discovery.
A plasma membrane-associated glycolytic metabolon is functionally coupled to KATP channels in pancreatic α and β cells from humans and mice.

Microbiol Spectr. 2023 Apr 10. e0356422

Unravelling Strain-Specific Modifications of Toxoplasma gondii tRNA and sncRNA Using LC-MS/MS.

Wei Wang, Yi Yang, Huanping Guo, Ming-Han Li, Xiao-Qing Chen, Xin-Yu Wei, Yu Chen, Hany M Elsheikha, Xiao-Xuan Zhang.

  Many RNA modifications have been detected in rRNA, tRNA and small noncoding RNA (sncRNA) as well as in low-abundance RNA species such mRNA. Although RNA modifications play roles in many cellular and biological processes in various domains of life, knowledge about the diversity and role of RNA modifications in Toxoplasma gondii is limited. In this study, RNA modifications in three T. gondii strains (RH type I, PRU type II, and VEG type III) with distinct virulence abilities were determined by liquid chromatography-tandem mass spectrometry. We compared the levels of modifications of four nucleotides in tRNA and sncRNA, characterized RNA modification patterns of different T. gondii strains, and determined the diversity of RNA modifications. We detected and quantified 22 modified nucleosides in both tRNA and sncRNA. Significant differences in the diversity of the modified nucleosides were found between the three T. gondii strains. RNA modifications were correlated with the expression of many T. gondii virulence proteins. Some of the identified modifications (e.g., 2'-O-methylinosine, pseudouridine) play a role in mediating the host-parasite interaction. These results provide novel insight into the global modifications in tRNA and sncRNA, and the diversity of RNA modifications between T. gondii strains with different virulence backgrounds. IMPORTANCE Although RNA modifications play roles in many cellular and developmental processes in various domains of life, knowledge about the patterns and functions of RNA modifications in T. gondii is limited. Here, a quantitative liquid chromatography-tandem mass spectrometry (LC-MS/MS) approach was used to study global RNA modifications in T. gondii strains of distinct virulence backgrounds. We quantified 22 modified nucleosides in both tRNA and sncRNA. Significant T. gondii strain-specific differences in RNA modifications were detected. More tRNA modifications correlated with T. gondii virulence proteins than sncRNA modifications. RNA modifications were significantly correlated with virulence proteins. Our data provide the first comprehensive profiling of the modifications tRNA and sncRNA in T. gondii, expanding the diversity of RNA modifications in this parasite and suggesting new regulators for modulating its virulence.

Keywords:  RNA modification; Toxoplasma gondii; epigenetics; sncRNA; tRNA; virulence

DOI:  https://doi.org/10.1128/spectrum.03564-22
Int J Parasitol. 2023 Apr 12. pii: S0020-7519(23)00074-7. [Epub ahead of print]

Short-term culture adaptation of Toxoplasma gondii archetypal II and III field isolates affects cystogenic capabilities and modifies virulence in mice.

Alicia Colos-Arango, Andrea Largo-de la Torre, Rafael Calero-Bernal, Luis Miguel Ortega-Mora, Javier Regidor-Cerrillo.

  Most Toxoplasma gondii research has been carried out using strains maintained in the laboratory for long periods of time. Long-term passage in mice or cell culture influences T. gondii phenotypic traits such as the capability to produce oocysts in cats and virulence in mice. In this work, we investigated the effect of cell culture adaptation in the short term for recently obtained type II (TgShSp1 (Genotype ToxoDB#3), TgShSp2 (#1), TgShSp3 (#3) and TgShSp16 (#3)) and type III (#2) isolates (TgShSp24 and TgPigSp1). With this purpose, spontaneous and alkaline stress-induced cyst formation in Vero cells during 40 passages, from passage 10 (p10) to 50 (p50), and isolate virulence at p10 versus p50 were studied using a harmonized bioassay method in Swiss/CD1 mice. Toxoplasma gondii cell culture maintenance showed a drastic loss of spontaneous and induced production of mature cysts after ≈ 25-30 passages. The TgShSp1, TgShSp16 and TgShSp24 isolates failed to generate spontaneously formed mature cysts at p50. Limited cyst formation was associated with an increase in parasite growth and a shorter lytic cycle. In vitro maintenance also modified T. gondii virulence in mice at p50 with events of exacerbation, increasing cumulative morbidity for TgShSp2 and TgShSp3 isolates and mortality for TgShSp24 and TgPigSp1 isolates, or attenuation, with absence of mortality and severe clinical signs for TgShSp16, and better control of the infection with the lowest parasite and cyst burdens in lungs and brain for the TgShSp1 isolate. The present findings show deep changes in relevant phenotypic traits in laboratory-adapted T. gondii isolates and open new discussion about their use for inferring keys to parasite biology and virulence.

Keywords:  Cell culture adaptation; Cyst formation; Mouse virulence; Phenotypic traits; Toxoplasma gondii; Type II and III genotypes

DOI:  https://doi.org/10.1016/j.ijpara.2023.03.004
Int J Parasitol Parasites Wildl. 2023 Aug;21 1-10

Exploring the epidemiological role of the Eurasian lynx (Lynx lynx) in the life cycle of Toxoplasma gondii.

Patrick Scherrer, Marie-Pierre Ryser-Degiorgis, Iris A Marti, Stéphanie Borel, Caroline F Frey, Norbert Mueller, Maja Ruetten, Walter Basso.

  Toxoplasma gondii is a successful coccidian parasite able to infect all warm-blooded animals and humans, causing one of the most common zoonoses worldwide. The Eurasian lynx (Lynx lynx) is one of the feline potential hosts of T. gondii in Switzerland, but little is known about its epidemiological role as a definitive or intermediate host. Serum samples from 183 Eurasian lynx collected from 2002 to 2021 were tested for antibodies to T. gondii by ELISA, IFAT and in case of inconclusive results, immunoblot. Antibodies to T. gondii were found in 150 of 183 (82%) Eurasian lynx. Older age, good health status and a low-altitude habitat were found to be significant predictors for seropositivity. T. gondii oocysts were detected in 3 of 176 (1.7%) faecal samples, indicating the Eurasian lynx as a definitive host. In addition, T. gondii DNA was detected in skeletal muscle (7/88), heart muscle (2/26) and/or brain tissue (2/36) from 10 different lynx by real-time PCR. In one animal, a T. gondii-like tissue cyst was observed in heart muscle and confirmed as T. gondii by immunohistochemistry (1/20) and real-time PCR. With an adapted nested-PCR-multilocus-sequence typing (MLST) and in silico restriction-fragment-length-polymorphism analysis (RFLP) approach two different T. gondii genotypes were detected: a lineage II variant (ToxoDB #3) in three animals (two oocyst samples and one heart muscle sample) and a novel genotype exhibiting both type II and III alleles in a further animal (skeletal muscle). The present results indicate that T. gondii infection is widespread in the Swiss lynx population. The Eurasian lynx may contribute to environmental contamination with oocysts and is able to harbour the parasite in different tissues. Genotyping revealed the presence of both a common T. gondii lineage in Europe and a previously unknown genotype and thus shedding more light on the complex molecular epidemiology of T. gondii.

Keywords:  ELISA; IFAT; RFLP; Risk factors; Zoonosis; qPCR

DOI:  https://doi.org/10.1016/j.ijppaw.2023.03.005
PLoS Pathog. 2023 Apr 14. 19(4): e1011329

Tim-3 regulates the immunosuppressive function of decidual MDSCs via the Fyn-STAT3-C/EBPβ pathway during Toxoplasma gondii infection.

Houbao Qi, Yuantao Li, Xianbing Liu, Yuzhu Jiang, Zhidan Li, Xiaoyan Xu, Haixia Zhang, Xuemei Hu.

Myeloid-derived suppressor cells (MDSCs) play a key role in maintaining maternal-fetal tolerance for a successful pregnancy, but the role of MDSCs in abnormal pregnancy caused by Toxoplasma gondii infection is unknown. Herein, we revealed a distinct mechanism by which T-cell immunoglobulin domain and mucin domain containing protein-3 (Tim-3), an immune checkpoint receptor that balances maternal-fetal tolerance during pregnancy, contributes to the immunosuppressive function of MDSCs during T. gondii infection. The expression of Tim-3 in decidual MDSCs was significantly downregulated following T. gondii infection. The proportion of monocytic MDSCs population, the inhibitory effect of MDSCs on T-cell proliferation, the levels of STAT3 phosphorylation, and the expression of functional molecules (Arg-1 and IL-10) in MDSCs were all decreased in T. gondii-infected pregnant Tim-3 gene knockout (Tim-3KO) mice compared with infected pregnant WT mice. After treatment with Tim-3-neutralizing Ab in vitro, the expression levels of Arg-1, IL-10, C/EBPβ, and p-STAT3 were decreased, the interaction between Fyn and Tim-3 or between Fyn and STAT3 was weakened, and the binding ability of C/EBPβ to the promoters of ARG1 and IL10 was decreased in human decidual MDSCs with T. gondii infection, while opposite results were observed following treatment with galectin-9 (a ligand for Tim-3). Inhibitors of Fyn and STAT3 also downregulated the expression of Arg-1 and IL-10 in decidual MDSCs and exacerbated adverse pregnancy outcomes caused by T. gondii infection in mice. Therefore, our studies discovered that the decrease of Tim-3 after T. gondii infection could downregulate the functional molecules of Arg-1 and IL-10 expression in decidual MDSCs through the Fyn-STAT3-C/EBPβ signaling pathway and weaken their immunosuppressive function, which eventually contribute to the development of adverse pregnancy outcomes.

DOI: https://doi.org/10.1371/journal.ppat.1011329
Molecules. 2023 Apr 03. pii: 3186. [Epub ahead of print]28(7):

Targeting Toxoplasma gondii ME49 TgAPN2: A Bioinformatics Approach for Antiparasitic Drug Discovery.

Ali Altharawi.

  As fewer therapeutic options are available for treating toxoplasmosis, newer antiparasitic drugs that can block TgAPN2 M1 aminopeptidase are of significant value. Herein, we employed several computer-aided drug-design approaches with the objective of identifying drug molecules from the Asinex library with stable conformation and binding energy scores. By a structure-based virtual screening process, three molecules-LAS_52160953, LAS_51177972, and LAS_52506311-were identified as promising candidates, with binding affinity scores of -8.6 kcal/mol, -8.5 kcal/mol, and -8.3 kcal/mol, respectively. The compounds produced balanced interacting networks of hydrophilic and hydrophobic interactions, vital for holding the compounds at the docked cavity and stable binding conformation. The docked compound complexes with TgAPN2 were further subjected to molecular dynamic simulations that revealed mean RMSD for the LAS_52160953 complex of 1.45 Å), LAS_51177972 complex 1.02 Å, and LAS_52506311 complex 1.087 Å. Another round of binding free energy validation by MM-GBSA/MM-PBSA was done to confirm docking and simulation findings. The analysis predicted average MM-GBSA value of <-36 kcal/mol and <-35 kcal/mol by MM-PBSA. The compounds were further classified as appropriate candidates to be used as drug-like molecules and showed favorable pharmacokinetics. The shortlisted compounds showed promising biological potency against the TgAPN2 enzyme and may be used in experimental validation. They may also serve as parent structures to design novel derivatives with enhanced biological potency.

Keywords:  MM-PBSA; Toxoplasma gondii; computer-aided drug design; molecular dynamic simulation; toxoplasmosis

DOI:  https://doi.org/10.3390/molecules28073186
Cell Rep. 2023 Apr 13. pii: S2211-1247(23)00405-9. [Epub ahead of print]42(4): 112394

A plasma membrane-associated glycolytic metabolon is functionally coupled to KATP channels in pancreatic α and β cells from humans and mice.

Thuong Ho, Evgeniy Potapenko, Dawn B Davis, Matthew J Merrins.

  The ATP-sensitive K+ (KATP) channel is a key regulator of hormone secretion from pancreatic islet endocrine cells. Using direct measurements of KATP channel activity in pancreatic β cells and the lesser-studied α cells, from both humans and mice, we provide evidence that a glycolytic metabolon locally controls KATP channels on the plasma membrane. The two ATP-consuming enzymes of upper glycolysis, glucokinase and phosphofructokinase, generate ADP that activates KATP. Substrate channeling of fructose 1,6-bisphosphate through the enzymes of lower glycolysis fuels pyruvate kinase, which directly consumes the ADP made by phosphofructokinase to raise ATP/ADP and close the channel. We further show the presence of a plasma membrane-associated NAD+/NADH cycle whereby lactate dehydrogenase is functionally coupled to glyceraldehyde-3-phosphate dehydrogenase. These studies provide direct electrophysiological evidence of a KATP-controlling glycolytic signaling complex and demonstrate its relevance to islet glucose sensing and excitability.

Keywords:  CP: Metabolism; K(ATP) channel; glycolysis; glycolytic metabolon; inside-out excised patch clamp; metabolic compartmentation; pyruvate kinase

DOI:  https://doi.org/10.1016/j.celrep.2023.112394