bims-toxgon Biomed News
on Toxoplasma gondii metabolism
Issue of 2022‒08‒21
eleven papers selected by
Lakesh Kumar
BITS Pilani

  1. Cell Rep. 2022 Aug 16. pii: S2211-1247(22)01041-5. [Epub ahead of print]40(7): 111224
      Toxoplasma gondii possesses sphingolipid synthesis capabilities and is equipped to salvage lipids from its host. The contribution of these two routes of lipid acquisition during parasite development is unclear. As part of a complete ceramide synthesis pathway, T. gondii expresses two serine palmitoyltransferases (TgSPT1 and TgSPT2) and a dihydroceramide desaturase. After deletion of these genes, we determine their role in parasite development in vitro and in vivo during acute and chronic infection. Detailed phenotyping through lipidomic approaches reveal a perturbed sphingolipidome in these mutants, characterized by a drastic reduction in ceramides and ceramide phosphoethanolamines but not sphingomyelins. Critically, parasites lacking TgSPT1 display decreased fitness, marked by reduced growth rates and a selective defect in rhoptry discharge in the form of secretory vesicles, causing an invasion defect. Disruption of de novo ceramide synthesis modestly affects acute infection in vivo but severely reduces cyst burden in the brain of chronically infected mice.
    Keywords:  Apicomplexa; CP: Immunology; CP: Microbiology; Toxoplasma gondii; biosynthesis; dihydroceramide desaturase; encystation; invasion; lipids; parasites; parasitophorous vacuole membrane; rhoptries; serine palmitoyltransferase; sphingolipids
  2. Front Cell Infect Microbiol. 2022 ;12 969832
      Toxoplasma gondii (T. gondii) infection can cause intestinal inflammation in rodents and significantly alters the structure of gut microbiota. However, the effects of different T. gondii genotypes on the gut microbiota of rats remain unclear. In this study, acute and chronic T. gondii infection in Fischer 344 rats was induced artificially by intraperitoneal injection of tachyzoites PYS (Chinese 1 ToxoDB#9) and PRU (Type II). Fecal 16S rRNA gene amplicon sequencing was employed to analyze the gut microbiota structure at different stages of infection, and to compare the effects of infection by two T. gondii genotypes. Our results suggested that the infection led to structural changes of gut microbiota in rats. At the acute infection stage, the microbiota diversity increased, while both diversity and abundance of beneficial bacteria decreased at the chronic infection stage. The differences of microbiota structure were caused by strains of different genotypes. However, the diversity changes were consistent. This study demonstrates that the gut microbiota plays an important role in T. gondii infection in rats. The data will improve our understanding of the association between T. gondii infection and gut microbiota in rodents.
    Keywords:  16S rRNA gene amplicon sequencing; Toxoplasma gondii; fischer 344 rats; genotype; gut microbiota
  3. Front Vet Sci. 2022 ;9 972500
      Toxoplasma gondii is an obligate intracellular protozoan that infects the nucleated cells of warm-blooded animals and causes life-threatening disease in immunocompromised patients. Due to the limited effectiveness and prominent side effects of existing drugs, there is an urgent need to develop new therapeutic options against T. gondii. Piceatannol is a natural plant compound with multiple functions such as antibacterial, antileukemic and antiparasitic activities. In the present study, the anti-T. gondii activity of piceatannol was evaluated. Piceatannol potently inhibited Toxoplasma with a half-maximal effective concentration (EC50) of 28.10 μM. Piceatannol showed a significant inhibitory effect on intracellular proliferation, inhibiting intracellular parasites at a rate of 98.9% when treatment with 100 μM piceatannol. However, the invasion ability of tachyzoites was not affected by piceatannol. By immunofluorescence assay, we noted that the parasite showed abnormalities in cell division after exposure to piceatannol. To determine the in vivo effect of piceatannol on acute infection, a model was established by infecting BALB/c mice with the virulent RH strain of T. gondii. Mice infected with 500 tachyzoites showed a significant therapeutic effect when treated with 15 mg/kg of piceatannol. These results suggest that piceatannol is a promising drug for the treatment of T. gondii.
    Keywords:  Toxoplasma gondii; antiparasitic; drug discovery; natural extraction products; piceatannol
  4. Infect Dis Obstet Gynecol. 2022 ;2022 1163655
      Introduction: Toxoplasma gondii infection can cause important complications during pregnancy. Threatened abortion may be a late indicator for infection in settings with high prevalence of toxoplasmosis. We aimed to determine the association between T. gondii infection and threatened abortion in women from northern Peru.Methods: We conducted a secondary analysis of a cross-sectional study in pregnant women from a hospital and a rural community in Lambayeque, Peru. Exposure variable was serological diagnosis of toxoplasmosis, defined as the demonstration of either IgM or IgG antibodies against T. gondii. Outcome variable was threatened abortion, defined as the diagnosis of bloody vaginal discharge or bleeding during the first half of pregnancy. Prevalence ratios were estimated in simple and multiple regression analyses.
    Results: Of 218 pregnant women, 35.8% presented positive serology for T. gondii and 14.7% had threatened abortion in their current pregnancy. Pregnant women with positive T. gondii infection had 2.45-fold higher frequency of threatened abortion (PR: 2.45, 95% CI: 1.15-5.21). In addition, the frequency of threatened abortion decreased by 9% for each additional year of age (PR: 0.91, 95% CI: 0.86-0.97). A previous history of threatened abortion also showed a higher frequency of threatened abortion (PR: 5.22, 95% CI: 2.45-11.12).
    Conclusions: T. gondii infection is associated with threatened abortion. An early age of pregnancy and a previous history of abortion are also associated with this condition.
  5. J Res Med Sci. 2022 ;27 48
      Background: Available data suggest that obesity is related to changes in the several adipocyte-derived proteins levels, which are involved in cancer recurrence. The purpose of this work was to investigate the correlation between obesity with metalloproteinase-9 (MMP-9), adiponectin and adiponectin and AMP-activated protein kinase (AMPK) levels by comparing serum levels of MMP-9, AMPK in normal weight and obese breast cancer survivors.Materials and Methods: In this cross-sectional study, 30 normal weight breast cancer survivors (body mass index [BMI] 18.5-25 kg/m2) and 30 obese breast cancer survivors (BMI ≥30 kg/m2) were investigated. Anthropometric parameters and serum levels of MMP-9, adiponectin, and AMPK were compared between the two groups.
    Results: No differences were detected in the serum levels of MMP-9, adiponectin, and AMPK in obese patients and normal weight patients (P > 0.05). There were no correlations between MMP-9, adiponectin, and AMPK levels with anthropometric measurements in two groups (P > 0.05).
    Conclusion: We found that there was a lack of correlation between obesity measures and serum levels of MMP-9, adiponectin, and AMPK. In breast cancer survivors, it seems that circulating levels of adiponectin, AMPK, and MMP-9 do not change in obesity state.
    Keywords:  AMP-activated protein kinase; Adiponectin; breast cancer; matrix metalloproteinase-9; obesity
  6. Acta Trop. 2022 Aug 10. pii: S0001-706X(22)00342-4. [Epub ahead of print] 106650
      Toxoplasma gondii, an opportunistic pathogenic protozoan, exhibits a strong predilection to infect the brain, causing severe neurological diseases, such as toxoplasmic encephalitis (TE), in immunocompromised patients. Microglia, the resident immune cells in the brain, is reported to play important roles in regulating the neuroinflammation mediated by T. gondii infection. Here we demonstrated that the tachyzoites of T. gondii RH strain could significantly upregulate the expression levels of microglial M1 phenotype markers including IL-1β, IL-6, TNF-α, iNOS and IL18 in activated murine BV2 microglia cells, which were regulated by T. gondii rhoptry protein 18 (TgROP18). Moreover, we found that TgROP18 could enhance the expression of M1 phenotype markers in activated murine BV2 microglia cells via activating NF-κB signal pathway. Additionally, TgROP18 was suggested to interact with the host p65 in activated murine BV2 microglia cells and induce the phosphorylation of p65 at S536. In summary, the present study demonstrated that TgROP18 could promote the activated microglia to polarize to M1 phenotype and enhanced the expression of pro-inflammatory factors via activating NF-κB signal pathway, which could contribute to elucidating the mechanism underlying the neuroinflammation mediated by activated microglia in the brain with T. gondii infection.
    Keywords:  M1 polarization; NF-κB signal pathway; TgROP18; Toxoplasma gondii; microglia
  7. Amino Acids. 2022 Aug 16.
      Previous work has shown that dietary L-arginine (Arg) supplementation reduced white fat mass in obese rats. The present study was conducted with cell models to define direct effects of Arg on energy-substrate oxidation in hepatocytes, skeletal muscle cells, and adipocytes. BNL CL.2 mouse hepatocytes, C2C12 mouse myotubes, and 3T3-L1 mouse adipocytes were treated with different extracellular concentrations of Arg (0, 15, 50, 100 and 400 µM) or 400 µM Arg + 0.5 mM NG-nitro-L-arginine methyl ester (L-NAME; an NOS inhibitor) for 48 h. Increasing Arg concentrations in culture medium dose-dependently enhanced (P < 0.05) the oxidation of glucose and oleic acid to CO2 in all three cell types, lactate release from C2C12 cells, and the incorporation of oleic acid into esterified lipids in BNL CL.2 and 3T3-L1 cells. Arg at 400 µM also stimulated (P < 0.05) the phosphorylation of AMP-activated protein kinase (AMPK) in all three cell types and increased (P < 0.05) NO production in C2C12 and BNL CL.2 cells. The inhibition of NOS by L-NAME moderately reduced (P < 0.05) glucose and oleic acid oxidation, lactate release, and the phosphorylation of AMPK and acetyl-CoA carboxylase (ACC) in BNL CL.2 cells, but had no effect (P > 0.05) on these variables in C2C12 or 3T3-L1 cells. Collectively, these results indicate that Arg increased AMPK activity and energy-substrate oxidation in BNL CL.2, C2C12, and 3T3-L1 cells through both NO-dependent and NO-independent mechanisms.
    Keywords:  Arginine; Metabolism; Muscle cells; Nitric oxide; Substrate oxidation; White adipocytes
  8. Elife. 2022 Aug 17. pii: e80336. [Epub ahead of print]11
      Apicomplexan parasites cause persistent mortality and morbidity worldwide through diseases including malaria, toxoplasmosis, and cryptosporidiosis. Ca2+ signaling pathways have been repurposed in these eukaryotic pathogens to regulate parasite-specific cellular processes governing the replicative and lytic phases of the infectious cycle, as well as the transition between them. Despite the presence of conserved Ca2+-responsive proteins, little is known about how specific signaling elements interact to impact pathogenesis. We mapped the Ca2+-responsive proteome of the model apicomplexan T. gondii via time-resolved phosphoproteomics and thermal proteome profiling. The waves of phosphoregulation following PKG activation and stimulated Ca2+ release corroborate known physiological changes but identify specific proteins operating in these pathways. Thermal profiling of parasite extracts identified many expected Ca2+-responsive proteins, such as parasite Ca2+-dependent protein kinases. Our approach also identified numerous Ca2+-responsive proteins that are not predicted to bind Ca2+, yet are critical components of the parasite signaling network. We characterized protein phosphatase 1 (PP1) as a Ca2+-responsive enzyme that relocalized to the parasite apex upon Ca2+ store release. Conditional depletion of PP1 revealed that the phosphatase regulates Ca2+ uptake to promote parasite motility. PP1 may thus be partly responsible for Ca2+-regulated serine/threonine phosphatase activity in apicomplexan parasites.
    Keywords:  cell biology; infectious disease; microbiology
  9. Curr Neuropharmacol. 2022 Aug 17.
      Alzheimer's disease (AD) is one of the most common neurodegenerative diseases worldwide. The occult nature of the onset and the uncertainty of the etiology largely impede the development of therapeutic strategies for AD. Previous studies revealed that the disorder of energy metabolism in the brains of AD patients appears far earlier than the typical pathological features of AD, suggesting a tight association between energy crisis and the onset of AD. Energy crisis in the brain is known to be induced by the reductions in glucose uptake and utilization, which may be ascribed to the diminished expressions of cerebral glucose transporters (GLUTs), insulin resistance, mitochondrial dysfunctions, and lactate dysmetabolism. Notably, the energy sensors such as peroxisome proliferators-activated receptor (PPAR), transcription factor EB (TFEB), AMP-activated protein kinase (AMPK) were shown to be the critical regulators of autophagy, and autophagy plays important roles in regulating beta-amyloid (Aβ) metabolism, tau phosphorylation, neuroinflammation, iron dynamics, as well as ferroptosis. In this study, we summarized the current knowledge on the molecular mechanisms involved in the energy dysmetabolism of AD, and discussed the interplays existing between energy crisis, autophagy and ferroptosis. In addition, we highlighted the potential network that autophagy may serve as a bridge between energy crisis and ferroptosis in the progression of AD. A deeper understanding of the relationship between energy dysmetabolism and AD may provide new strategies for treating AD, meanwhile, the energy crisis in the progression of AD should gain more attention.
    Keywords:  Alzheimer's disease; autophagy; beta-amyloid; energy crisis; ferroptosis; iron metabolism; tau protein
  10. J Biol Chem. 2022 Aug 10. pii: S0021-9258(22)00807-9. [Epub ahead of print] 102364
      The heterogeneous nuclear ribonucleoprotein hnRNP A1 is a nucleocytoplasmic-shuttling RNA-binding protein that plays an important role in nucleic acid metabolism and gene expression regulation. The function of hnRNP A1 is determined in part by its specific location within the cell. Although some work has been done to elucidate the signaling pathways that regulate the cellular localization of hnRNP A1, the precise mechanism(s), including physiological and pathophysiological conditions that alter hnRNP A1 localization, are not known. We previously conducted an unbiased RNAi-based kinome-wide screen to identify kinases that regulate hnRNP A1 localization during hypertonic stress. One of the hits from this screen is AMPK-related protein kinase 5 (ARK5). Here, we validate ARK5 as the kinase responsible for controlling hnRNP A1 subcellular localization in response to hypertonic stress. We find using immunoprecipitation and in vitro kinase assay methods that ARK5 directly interacts with and phosphorylates hnRNP A1 on serine residues within the F-peptide region. We further show that the M9 motif of hnRNP A1 is essential for the ARK5-hnRNP A1 interaction and subsequent phosphorylation. In addition, the silencing of ARK5 increases the expression of anti-apoptotic protein Bcl-xL and consequently delays caspase activation during hypertonic stress. Our results indicate that ARK5 phosphorylates hnRNP A1 and regulates its subcellular localization during hypertonic stress.
    Keywords:  AMPK-related protein kinase 5 (ARK5); Bcl‐xL; Caspase; Co-Immunoprecipitation; Hypertonic stress; heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1); phosphorylation
  11. Life Sci Alliance. 2022 Oct;pii: e202201433. [Epub ahead of print]5(10):
      Histone acetylation levels are reduced during mitosis. To study the mitotic regulation of H3K9ac, we used an array of inhibitors targeting specific histone deacetylases. We evaluated the involvement of the targeted enzymes in regulating H3K9ac during all mitotic stages by immunofluorescence and immunoblots. We identified HDAC2, HDAC3, and SIRT1 as modulators of H3K9ac mitotic levels. HDAC2 inhibition increased H3K9ac levels in prophase, whereas HDAC3 or SIRT1 inhibition increased H3K9ac levels in metaphase. Next, we performed ChIP-seq on mitotic-arrested cells following targeted inhibition of these histone deacetylases. We found that both HDAC2 and HDAC3 have a similar impact on H3K9ac, and inhibiting either of these two HDACs substantially increases the levels of this histone acetylation in promoters, enhancers, and insulators. Altogether, our results support a model in which H3K9 deacetylation is a stepwise process-at prophase, HDAC2 modulates most transcription-associated H3K9ac-marked loci, and at metaphase, HDAC3 maintains the reduced acetylation, whereas SIRT1 potentially regulates H3K9ac by impacting HAT activity.