bims-toxgon Biomed News
on Toxoplasma gondii metabolism
Issue of 2022‒08‒28
27 papers selected by
Lakesh Kumar
BITS Pilani

  1. Microorganisms. 2022 Aug 05. pii: 1577. [Epub ahead of print]10(8):
      Toxoplasma gondii is a protozoan parasite responsible for human toxoplasmosis. The three major clonal lineages and different recombinant strains of T. gondii have a varied global distribution. This study aimed at evaluating the epidemiological distribution of types II and I-III and recombinant or mixed T. gondii in Italians and foreigners residing in Italy, establishing an association between serotypes and demographic characteristics. We collected the sera of 188 subjects who had tested positive for specific T. gondii antibodies. The population was differentiated into groups based on sex, nationality, and place of birth (Italy, Africa, South America, Asia, or Europe (except Italy)). We then performed a homemade ELISA test that detected both the antibodies against the amino acid sequences of the three main genotype antigens (I-III) in human sera and discerned the T. gondii strains. Serotype II of T. gondii was the most prevalent in the Italian population, whereas type I-III was the most prevalent in the foreign group. Surprisingly, we observed a notable amount of recombinant or mixed serotypes in European and Italian subjects. Moreover, we showed a significant difference in the prevalence of T. gondii serotypes between men and women, Italians, and foreigners. This descriptive study is the first to investigate the epidemiological distribution of T. gondii serotypes in humans in Italy using a homemade ELISA. We considered this technique suitable for discriminating between serotypes II and I-III and, consequently, for an epidemiological study focusing on the observation of circulating T. gondii strains and clinical correlations.
    Keywords:  Italians; Toxoplasma gondii; epidemiology; migrants; serotype ELISA
  2. Sci Total Environ. 2022 Aug 18. pii: S0048-9697(22)05267-6. [Epub ahead of print] 158168
      Scientists' concerns are growing regarding the potential adverse impact of Toxoplasma gondii contamination of the marine environment on marine wildlife and public health. Terrestrial runoff is a significant route for dissemination of T. gondii oocysts from land to sea. Yet, the influence of terrestrial runoff on T. gondii prevalence in marine animals in China is largely unknown. To address this concern, we examined the presence of T. gondii in marine oysters Crassostrea spp., rockfish Sebastes schlegelii (S. schlegelii), fat greenling fish Hexagrammos otakii (H. otakii), and Asian paddle crab Charybdis japonica (C. japonica) using a PCR assay targeting T. gondii B1 gene. A total of 1920 samples were randomly collected, in Jan-Dec 2020, from terrestrial runoff areas (TRA, TRB, and TRC) and non-terrestrial runoff area (Grape bay) in Weihai, China. T. gondii prevalence in TRB and TRC was 6.04 % and 5.83 %, respectively, which was higher than 2.29 % detected in the non-terrestrial runoff area. The highest prevalence was detected in Crassostrea spp., and a correlation was observed between T. gondii prevalence and weight of Crassostrea spp. The temperature, but not precipitation, significantly correlated with T. gondii prevalence. Understanding the fate of T. gondii delivered to oceans by terrestrial runoff is critical for predicting future disease risks for marine wildlife and humans.
    Keywords:  Epidemiology; Marine ecosystems; Terrestrial runoff; Toxoplasma gondii
  3. Antibodies (Basel). 2022 Aug 15. pii: 52. [Epub ahead of print]11(3):
      Toxoplasma gondii, an obligate intracellular protozoan parasite, is the causative agent of one of the most prevalent zoonoses worldwide. T. gondii infection is extremely important from a medical point of view, especially for pregnant women, newborns with congenital infections, and immunocompromised individuals. Thus, an accurate and proper diagnosis of this infection is essential. Among the available diagnostic tests, serology is commonly used. However, traditional serological techniques have certain limitations in evaluating the duration of T. gondii infection, which is problematic, especially for pregnant women. Avidity of T. gondii-specific IgG antibodies seems to be a significant tool for discrimination between recent and distant infections. This article describes the problem of diagnosis of T. gondii infection, with regard to IgG avidity tests. The IgG avidity test is a useful serological indicator of toxoplasmosis, which in many cases can confirm or exclude the active form of the disease. IgG antibodies produced in the recent primary T. gondii infection are of low avidity while IgG antibodies with high avidity are detected in the chronic phase of infection. Furthermore, this paper presents important topics of current research that concern the usage of parasite recombinant antigens that may improve the performance of IgG avidity tests.
    Keywords:  IgG avidity; Toxoplasma gondii; diagnosis; recombinant antigen; toxoplasmosis
  4. Pharmaceutics. 2022 Aug 05. pii: 1634. [Epub ahead of print]14(8):
      Toxoplasma gondii is a protozoan that infects up to a third of the world's population. This parasite can cause serious problems, especially if a woman is infected during pregnancy, when toxoplasmosis can cause miscarriage, or serious complications to the baby, or in an immunocompromised person, when the infection can possibly affect the patient's eyes or brain. To identify potential drug candidates that could counter toxoplasmosis, we selected 13 compounds which were pre-screened in silico based on the proteome of T. gondii to be evaluated in vitro against the parasite in a cell-based assay. Among the selected compounds, three demonstrated in vitro anti-T. gondii activity in the nanomolar range (almitrine, bortezomib, and fludarabine), and ten compounds demonstrated anti-T. gondii activity in the micromolar range (digitoxin, digoxin, doxorubicin, fusidic acid, levofloxacin, lomefloxacin, mycophenolic acid, ribavirin, trimethoprim, and valproic acid). Almitrine demonstrated a Selectivity Index (provided by the ratio between the Half Cytotoxic Concentration against human foreskin fibroblasts and the Half Effective Concentration against T. gondii tachyzoites) that was higher than 47, whilst being considered a lead compound against T. gondii. Almitrine showed interactions with the Na+/K+ ATPase transporter for Homo sapiens and Mus musculus, indicating a possible mechanism of action of this compound.
    Keywords:  Toxoplasma gondii; bioinformatics; drug discovery; drug repurposing; drug targets; in vitro screening; toxoplasmosis
  5. Pathogens. 2022 Aug 12. pii: 909. [Epub ahead of print]11(8):
      Toxoplasma gondii constitutes a major zoonotic agent but also has been frequently identified as an important cause of clinical disease (e.g., abortion, pneumonia, encephalitis) in wildlife; specifically, T. gondii has been associated with neurological disease in cetaceans. This study investigated the genetic diversity of T. gondii strains involved in infections in dolphins found stranded in the Mediterranean coastlines of Italy. Tissue samples from 16 dolphins (Stenella coeruleoalba and Tursiops truncatus species) positive for T. gondii-DNA presence by PCR were examined by histology and subjected to further genetic characterization of strains detected by PCR-RFLP and multilocus PCR-sequencing assays. According to fully genotyped samples, the genotypes ToxoDB#3 (67%) and #2 (22%) were detected, the latter being reported for the first time in cetaceans, along with a mixed infection (11%). Subtyping by PCR-seq procedures provided evidence of common point mutations in strains from southwestern Europe. Despite evidence of T. gondii as a cause of neurological disease in dolphins, sources of infections are difficult to identify since they are long-living animals and some species have vast migration areas with multiple chances of infection. Finally, the genetic diversity of T. gondii found in the dolphins studied in the Mediterranean coastlines of Italy reflects the main genotypes circulating inland in the European continent.
    Keywords:  Mediterranean Sea; PCR-RFLP; PCR-sequencing; Toxoplasma gondii; cetaceans; genotype
  6. Pathogens. 2022 Aug 01. pii: 868. [Epub ahead of print]11(8):
      Toxoplasma gondii (T. gondii) is a protozoan parasite, which infects a wide variety of mammals and bird species globally. In large parts of the world, this parasite is relatively well documented in wildlife species, however, this topic is poorly documented in Africa. The current review systematically explores the presence and distribution of T. gondii in African wildlife species through a key word search in PubMed, Web of Science and CAB Direct. A total of 66 records were identified and included in the qualitative analysis, of which 19 records were retained for the quantitative synthesis. The presence of T. gondii was reported in a wide range of wildlife species, found in twelve countries, spread over the African continent. The retained records report a prevalence range of 6-100% in herbivores, 8-100% in omnivores and 14-100% in carnivores. In wild felines (cheetahs, leopards, and lions) a prevalence range of 33-100% was found. Reports from South Africa, and on the presence of T. gondii in lion were most common. Overall, the results indicate the scarcity of information on T. gondii in Africa and its circulation in wildlife. The lack of knowledge on the parasite in Africa, especially in areas at the human-livestock-wildlife interface, prevents us from understanding how prevalent it is on the continent, what strains are circulating in wildlife and what the most common routes of transmission are in the different habitats in Africa.
    Keywords:  Africa; Toxoplasma gondii; prevalence; wildlife
  7. J Cell Biol. 2022 Sep 05. pii: e202111084. [Epub ahead of print]221(9):
      Kinetochores are multiprotein assemblies directing mitotic spindle attachment and chromosome segregation. In apicomplexan parasites, most known kinetochore components and associated regulators are apparently missing, suggesting a minimal structure with limited control over chromosome segregation. In this study, we use interactomics combined with deep homology searches to identify 13 previously unknown components of kinetochores in Apicomplexa. Apicomplexan kinetochores are highly divergent in sequence and composition from animal and fungal models. The nanoscale organization includes at least four discrete compartments, each displaying different biochemical interactions, subkinetochore localizations and evolutionary rates across the phylum. We reveal alignment of kinetochores at the metaphase plate in both Plasmodium berghei and Toxoplasma gondii, suggestive of a conserved "hold signal" that prevents precocious entry into anaphase. Finally, we show unexpected plasticity in kinetochore composition and segregation between apicomplexan lifecycle stages, suggestive of diverse requirements to maintain fidelity of chromosome segregation across parasite modes of division.
  8. Foods. 2022 Aug 22. pii: 2542. [Epub ahead of print]11(16):
      Toxoplasma gondii is an obligate intracellular parasite that causes toxoplasmosis, with approximately one third of the population around the world seropositive. The consumption of contaminated food is the main source of infection. These include meat products with T. gondii tissue cysts, and dairy products with tachyzoites. Recently, contamination has been detected in fresh products with oocysts and marine products. Despite the great health problems that are caused by T. gondii, currently there are no standardized methods for its detection in the food industry. In this review, we analyze the current detection methods, the prevalence of T. gondii in different food products, and the control measures. The main detection methods are bioassays, cell culture, molecular and microscopic techniques, and serological methods, but some of these do not have applicability in the food industry. As a result, emerging techniques are being developed that are aimed at the detection of multiple parasites simultaneously that would make their application more efficient in the industry. Since the prevalence of this parasite is high in many products (meat and milk, marine products, and vegetables), it is necessary to standardize detection methods, as well as implement control measures.
    Keywords:  Toxoplasma gondii; control; detection; food; toxoplasmosis
  9. Animals (Basel). 2022 Aug 15. pii: 2080. [Epub ahead of print]12(16):
      Neospora caninum has a worldwide economic impact as an important cause of abortion in cattle, while Toxoplasma gondii, another abortifacient pathogen, is globally a major foodborne zoonotic threat. The study aimed to evaluate the seroprevalence and risk factors for the two parasites in cattle in Portugal. A total of 612 sera from 35 farms were tested by an in-house p30 ELISA for T. gondii and p38 ELISA for N. caninum. T. gondii positive and suspicious sera were confirmed by p30 Western blot or IFAT. T. gondii and N. caninum animal seroprevalence was 9.2% (95%CI 7.1-11.7) and 17.2% (95% CI 14.4-20.4) and herd seroprevalence was 51.4% (95% CI 35.6-67.0) and 68.6% (95% CI 52.0-81.5), respectively. At the univariable level, climate area and precipitation of wettest month, driest month, driest quarter, and warmest quarter were significant predictors of seropositivity for both. N. caninum seropositivity was more likely in the region Norte, densely populated areas, and intensive production, and the probability of T. gondii seropositivity decreased with herd size. Results confirm the need to consider neosporosis in the differential diagnosis of cattle reproductive disorders in Portugal and may be valuable to inform source attribution models for human toxoplasmosis.
    Keywords:  Neospora caninum; Portugal; Toxoplasma gondii; cattle; risk factors; seroprevalence
  10. Front Microbiol. 2022 ;13 944006
      Exogenous pathogen infection can induce autophagy in cells. Autophagy is essential for cell survival, development, and homeostasis. It not only regulates cell defense and stress, but also has a close relationship with innate and adaptive immunity. Complement is an important part of innate immunity, which could be activated by three approaches, including classic, alternative, and lectin pathways. All the three pathways result in the activation of C3, and generate anaphylatoxin fragments C3a and C5a, and formation of the membrane attack complex. Either C3a or C5a induces the inflammatory cytokines through binding to C3aR or C5aR, respectively. However, it is still unknown whether the complement could regulate the autophagy of intracellular microorganisms or not. In this study, we constructed a Toxoplasma gondii (T. gondii) and macrophages co-culture experimental model using T. gondii expressing enhanced green fluorescence protein (EGFP) fluorescence and C3-/-C57BL/6 J mice for that T. gondii invaded peritoneal macrophages in mice. Western blot, laser confocal microscopy (LCM), and transmission electron microscopy (TEM) were used to observe the changes of autophagy between the macrophages from wild-type (WT) and C3-/- mice. Flow cytometry and LCM were used to investigate the effect of autophagy on the killing ability of macrophages against T. gondii. Here, we found that local C3 could suppress not only the canonical autophagy of macrophage, but also the xenophagy to T. gondii. Interestingly, the inhibition of C3 on host cell autophagy could significantly suppress the clearance of T. gondii by the IFN-γ-primed macrophage. Finally, we investigated the mechanism of the autophagy regulation of C3 that the effect of C3 on the macrophage-specific autophagy against T. gondii depends on mTOR. And, there is C3a but not C5a/C5aR involved in regulating macrophage xenophagy against T. gondii. Collectively, our findings suggest locally generated C3 regulates the clearance of T. gondii by Macrophage through the regulation of the non-canonical IFN-γ-dependent autophagy pathway, and paint a clearer picture in the regulation of autophagy by innate immune components.
    Keywords:  C3; Toxoplasma; autophagy; macrophage; xenophagy
  11. Genes (Basel). 2022 Aug 19. pii: 1482. [Epub ahead of print]13(8):
      Toxoplasma gondii is an opportunistic protozoan parasite known to affect the human brain. The infection has been associated with an increased incidence of schizophrenia; however, the link between the two conditions remains unclear. This study aimed to compare the plasma metabolome of schizophrenia and non-schizophrenia subjects with or without Toxoplasma infection. Untargeted metabolomic profiling was carried out by liquid chromatography-mass spectrometry. Elevation of the α-hydroxyglutaric acid level and reduced adenosine monophosphate, inosine, hypoxanthine and xanthine were found in the subjects with either toxoplasmosis or schizophrenia alone. These results suggest that purine catabolism is a common metabolic alteration in Toxoplasma infection and schizophrenia. The roles of these metabolites on the pathogenesis of schizophrenia in relation to Toxoplasma infection warrant further studies.
    Keywords:  Toxoplasma gondii; metabolomics; purine catabolism; schizophrenia; toxoplasmosis
  12. Cell Mol Biol (Noisy-le-grand). 2022 Apr 30. 68(4): 122-128
      Toxoplasmosis, caused by Toxoplasma gondii, is one of the most prevalent parasite ‎illnesses in humans. Although primary infection in a pregnant woman is usually asymptomatic, it has the potential to cause significant harm to the fetus, including miscarriage. In this study, we ‎investigate the usefulness of the PCR to confirm the etiology of the abortion. A prospective ‎study in the Al-Diwaniyah maternity and pediatric teaching hospital in Iraq was conducted. The research comprised 94 aborted women. We have reported a new ‎internal primer for the nested PCR protocol to detect toxoplasmosis. In the 94-aborted ‎women, 30 samples (31.9 %) were positive by the nPCR using the G529 repeat gene and ‎qPCR using B1 gene primers. We have shown that three women carry the ‎parasite in their placentas, and at the same time, they do not carry antibodies in their blood.‎ We recommend that women should be aware of the risk of toxoplasmosis and the ‎importance of preventing measures. In addition, PCR should be done in the case of ‎abortion to enhance sensitivity even if serology is negative.
  13. Front Immunol. 2022 ;13 950914
      The obligate intracellular parasite Toxoplasma gondii makes use of infected leukocytes for systemic dissemination. Yet, how infection impacts the processes of leukocyte diapedesis has remained unresolved. Here, we addressed the effects of T. gondii infection on the trans-endothelial migration (TEM) of dendritic cells (DCs) across polarised brain endothelial monolayers. We report that upregulated expression of leukocyte ICAM-1 is a feature of the enhanced TEM of parasitised DCs. The secreted parasite effector GRA15 induced an elevated expression of ICAM-1 in infected DCs that was associated with enhanced cell adhesion and TEM. Consequently, gene silencing of Icam-1 in primary DCs or deletion of parasite GRA15 reduced TEM. Further, the parasite effector TgWIP, which impacts the regulation of host actin dynamics, facilitated TEM across polarised endothelium. The data highlight that the concerted action of the secreted effectors GRA15 and TgWIP modulate the leukocyte-endothelial interactions of TEM in a parasite genotype-related fashion to promote dissemination. In addition to the canonical roles of endothelial ICAM-1, this study identifies a previously unappreciated role for leukocyte ICAM-1 in infection-related TEM.
    Keywords:  apicomplexa; blood-brain barrier; cell adhesion molecule (CAM); immune cell; leukocyte; trans-endothelial migration
  14. Animals (Basel). 2022 Aug 09. pii: 2012. [Epub ahead of print]12(16):
      Members of the Felidae family are the definitive host of the ubiquitous zoonotic parasite Toxoplasma gondii. Few studies have been conducted to determine the epidemiology of T. gondii in domestic felines within animal shelter populations. The goal of this study was to assess seroprevalence in a limited-admission shelter in the greater Philadelphia area. Serum samples were collected from cats at a shelter in Media, Pennsylvania during the summer of 2018 to assess the proportion of the population that was IgM or IgG seropositive for antibodies against T. gondii, using a commercially available ELISA. Out of the 84 cats that were sampled, 24 cats were seropositive, giving a population prevalence of 28.6%. Nine cats were seropositive for IgM, nine were seropositive for IgG, and six were seropositive for both IgM and IgG. Based on our data, we found that a large percentage of this population was seronegative. Although the sample size in this study was limited and prevented us from obtaining statistically significant results, this research can serve as a pilot study for further investigations into the seroprevalence of toxoplasmosis among shelter-housed felines.
    Keywords:  prevalence; seroepidemiologic studies; shelter-housed cats; toxoplasma; zoonoses
  15. Infect Disord Drug Targets. 2022 Aug 20.
      OBJECTIVE: This study is about anti-Toxoplasma gondii activity of curcumin: a systematic review of pre-clinical studies.METHODS: In this systematic review, anti-parasitic activity of Curcuma longa on Toxoplasma gondii was assessed. Therefore, several databases, including PubMed, Scopus, Web of Science, Embase and Google Scholar were searched from 2010 to 2020.
    RESULTS: Of the 2200 papers retrieved between 2010 and 2020, six articles were reliable and were scrutinized. From 2 in vitro studies, the most used strain was RH strain of Toxoplasma gondii, whereas among 4 in vivo studies, RH strain with 2 (50%) studies, Me49 strain with 1(25%) study, RH and Me49 strain with 1(25%) studies, From four in vivo studies, the most used animal model was BALB/c, and Swiss albino with 1 study (25%) and Albino rats with 1 study (25%).
    CONCLUSION: The combination of curcumin and nanoparticles formulated with curcumin are new and useful agents for the treatment of parasitic diseases and reduction of drug resistance. The success of this therapeutic approach stems from the specific action of Curcuma longa against parasites and pathogens.
    Keywords:  Curcuma longa; Curcumin; Parasitic activity; Pre-clinical studies; Systematic review.; Toxoplasma gondii
  16. Microorganisms. 2022 Aug 15. pii: 1647. [Epub ahead of print]10(8):
      Abortion in livestock is a public health burden, and the cause of economic losses for farmers. Abortion can be multifactorial, and a deep diagnostic investigation is important to reduce the spread of zoonotic disease and public health prevention. In our study, a multidisciplinary investigation was conducted to address the cause of increased abortion and lamb mortality on a farm, which detected a co-infection of Listeria monocytogenes and Toxoplasma gondii. Hence, it was possible to conclude that this was the reason for a reduced flock health status and the cause of an increased abortion rate. Furthermore, the investigation work and identification of the L. monocytogenes infection root allowed the reduction of economic loss.
    Keywords:  L. monocytogenes; T. gondii; abortion; sheep
  17. Trends Parasitol. 2022 Aug 20. pii: S1471-4922(22)00179-9. [Epub ahead of print]
      The apicoplast, a relict plastid found in most species of the phylum Apicomplexa, harbors the ferredoxin redox system which supplies electrons to enzymes of various metabolic pathways in this organelle. Recent reports in Toxoplasma gondii and Plasmodium falciparum have shown that the iron-sulfur cluster (FeS)-containing ferredoxin is essential in tachyzoite and blood-stage parasites, respectively. Here we review ferredoxin's crucial contribution to isoprenoid and lipoate biosynthesis as well as tRNA modification in the apicoplast, highlighting similarities and differences between the two species. We also discuss ferredoxin's potential role in the initial reductive steps required for FeS synthesis as well as recent evidence that offers an explanation for how NADPH required by the redox system might be generated in Plasmodium spp.
    Keywords:  Apicomplexa; ferredoxin; isoprenoids; malaria; redox system; toxoplasmosis
  18. Front Physiol. 2022 ;13 928964
      AMP-activated protein kinase (AMPK) activation is considered a useful strategy for the treatment of type 2 diabetes (T2D). It is unclear whether the expression and/or activity of AMPK in adipocytes is dysregulated in obesity. Also, the expression/activity pattern of AMPKβ isoforms, which are targets for AMPK activators, in adipocytes remains elusive. In this study we show that the two AMPKβ isoforms make roughly equal contributions to AMPK activity in primary human and mouse adipocytes, whereas in cultured 3T3-L1 adipocytes of mouse origin and in primary rat adipocytes, β1-associated activity clearly dominates. Additionally, we found that obesity is not associated with changes in AMPK subunit expression or kinase activity in adipocytes isolated from subcutaneous adipose tissue from individuals with various BMI.
    Keywords:  AMPKβ; adipocytes; expression; human; kinase activity; obesity
  19. Microorganisms. 2022 Aug 17. pii: 1659. [Epub ahead of print]10(8):
      Diagnosis of Toxoplasma gondii acute infection was first attempted by detection of specific IgM antibodies, as for other infectious diseases. However, it was noted that this immunoglobulin declines slowly and may last for months or even years. Apart from the diagnostic problem imposed on clinical management, this phenomenon called our attention due to the underlying phenomena that may be causing it. We performed a systematic comparison of reports studying IgM antibody kinetics, and the data from the papers were used to construct comparative plots and other graph types. It became clear that this phenomenon is quite generalized, and it may also occur in animals. Moreover, this is not a technical issue, although some tests make more evident the prolonged IgM decay than others. We further investigated biological reasons for its occurrence, i.e., infection dynamics (micro-reactivation-encystment, reinfection and reactivation), parasite strain relevance, as well as host innate, natural B cell responses and Ig class-switch problems inflicted by the parasite. The outcomes of these inquiries are presented and discussed herein.
    Keywords:  IgM; Toxoplasma gondii; serological diagnosis
  20. PLoS Pathog. 2022 Aug 22. 18(8): e1010776
      The phylum Apicomplexa includes thousands of species of unicellular parasites that cause a wide range of human and animal diseases such as malaria and toxoplasmosis. To infect, the parasite must first initiate active movement to disseminate through tissue and invade into a host cell, and then cease moving once inside. The parasite moves by gliding on a surface, propelled by an internal cortical actomyosin-based motility apparatus. One of the most effective invaders in Apicomplexa is Toxoplasma gondii, which can infect any nucleated cell and any warm-blooded animal. During invasion, the parasite first makes contact with the host cell "head-on" with the apical complex, which features an elaborate cytoskeletal apparatus and associated structures. Here we report the identification and characterization of a new component of the apical complex, Preconoidal region protein 2 (Pcr2). Pcr2 knockout parasites replicate normally, but they are severely diminished in their capacity for host tissue destruction due to significantly impaired invasion and egress, two vital steps in the lytic cycle. When stimulated for calcium-induced egress, Pcr2 knockout parasites become active, and secrete effectors to lyse the host cell. Calcium-induced secretion of the major adhesin, MIC2, also appears to be normal. However, the movement of the Pcr2 knockout parasite is spasmodic, which drastically compromises egress. In addition to faulty motility, the ability of the Pcr2 knockout parasite to assemble the moving junction is impaired. Both defects likely contribute to the poor efficiency of invasion. Interestingly, actomyosin activity, as indicated by the motion of mEmerald tagged actin chromobody, appears to be largely unperturbed by the loss of Pcr2, raising the possibility that Pcr2 may act downstream of or in parallel with the actomyosin machinery.
  21. Talanta. 2022 Aug 13. pii: S0039-9140(22)00624-5. [Epub ahead of print]252 123828
      Toxoplasma gondii infection is a usual worldwide issue since a broad range of vertebrate hosts are infected by this famous parasite. However fetuses and immuno-compromised patients infected by parasite is of specific concern. Developing the easy-to-use, accurate, real time and selective methods for detection of toxoplasma infection has a key role in the treatment and management of patients. In this regard, rapid detection methods with reproducible outcomes during short period are highly interested. In this review, we discussed the recent developed molecular-based laboratory methods for detecting of Toxoplasma infection and also rapid diagnostic methods, especially optic and electrochemical based biosensors with point-of-care features.
    Keywords:  Biomarker; Biosensors; Detection; Toxoplasmosis
  22. Tissue Cell. 2022 Aug 09. pii: S0040-8166(22)00168-9. [Epub ahead of print]78 101896
      Hyperpolarization is associated with decreased intracellular Na+ concentration through the closure of the epithelial Na+ channels (ENaCs) during capacitation. 5'-AMP-activated protein kinase (AMPK) is involved in the regulation of Na+ transport by reducing ENaC-β abundance in the plasma membrane in somatic cells. However, it is not known whether AMPK acts on ENaCs in sperm. The aim of the present study was to analyze the role of AMPK activation in the regulation of ENaC and to examine its relationship with capacitation-associated hyperpolarization of human sperm. Human sperm were treated with AICAR (AMPK activator) in non-capacitating and capacitating conditions. AMPK activity and ENaC-β concentration were evaluated by ELISA. Flow cytometry was used to measure tyrosine phosphorylation, hyperpolarization, intracellular Na+ concentration and acrosome reaction. Immunofluorescence staining was carried out to analyze the distribution of ENaC-β and CD46 in sperm. We found that induction of capacitation triggered AMPK phosphorylation. AMPK activation by AICAR increased tyrosine phosphorylation. AICAR decreased ENaC-β levels, mainly localized at the principal-piece of the flagellum, resulting in lower intracellular Na+ concentration and increased hyperpolarization of the plasma membrane. Altogether, these data provide evidence that AMPK activation is involved in capacitation-associated hyperpolarization by reducing ENaC abundance in human sperm.
    Keywords:  5'-AMP-activated protein kinase (AMPK); Capacitation; Epithelial Sodium Channel (ENaC); Human sperm; Hyperpolarization
  23. J Appl Toxicol. 2022 Aug 23.
      Perfluorooctane sulfonate (PFOS) is a hepatotoxic environmental organic pollutant that can cause aberrant lipid accumulation in the liver. However, the molecular mechanism underlying PFOS-induced hepatic steatosis remains unclear. Our research showed that subchronic PFOS exposure inhibited AMP-activated protein kinase (AMPK) phosphorylation, leading to increased acetyl-CoA carboxylase (ACC) activity, attenuated fatty acid β-oxidation and consequent liver lipid accumulation. We found that 1 mg/kg/day PFOS exposure significantly aggravated steatosis in high-fat diet (HFD)-fed mice, along with reduced AMPK activity. Oil Red O results showed that PFOS exposure caused fat accumulation in HepG2 cells. As predicted, PFOS treatment reduced the level of phosphorylated AMPK in a concentration-dependent manner, leading to subsequent increase in ACC activity and lipid droplet accumulation in HepG2 cells. Treatment with 200 μM AMPK agonist AICAR alleviated PFOS-induced ACC activation and lipid accumulation. In summary, our data highlights a crucial role of AMPK/ACC pathway in PFOS-mediated liver lipid metabolic disorders.
    Keywords:  AMPK; PFOS; hepatotoxicity; high-fat diet; lipid metabolism
  24. J Cell Sci. 2022 Aug 26. pii: jcs.259609. [Epub ahead of print]
      AMP-activated protein kinase (AMPK) is a crucial cellular nutrient and energy sensor that maintains energy homeostasis. AMPK also governs cancer cell invasion and migration by regulating gene expression and activating multiple cellular signaling pathways. ADP-ribosylation factor 6 (Arf6) can be activated via nucleotide exchange by guanine nucleotide exchange factors (GEFs), and its activation also regulates tumor invasion and migration. By studying GEF-mediated Arf6 activation, we elucidated that AMPK functions as a noncanonical GEF for Arf6 in a kinase-independent manner. Moreover, by examining the physiological role of the AMPK-Arf6 axis, we determined that AMPK activates Arf6 upon glucose starvation and 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR) treatment. We further identified the binding motif in the C-terminal regulatory domain of AMPK that is responsible for promoting Arf6 activation and thus inducing cell migration and invasion. These findings reveal a noncanonical role of AMPK in which its C-terminal regulatory domain serves as a GEF for Arf6 during energy deprivation.
    Keywords:  ADP-ribosylation factor; Cell invasion; GTPase; Glucose deprivation
  25. Biomolecules. 2022 Aug 13. pii: 1115. [Epub ahead of print]12(8):
      Centrins are calcium (Ca2+)-binding proteins that are involved in many cellular functions including centrosome regulation. A known cellular target of centrins is SFI1, a large centrosomal protein containing multiple repeats that represent centrin-binding motifs. Recently, a protein homologous to yeast and mammalian SFI1, denominated TgSFI1, which shares SFI1-repeat organization, was shown to colocalize at centrosomes with centrin 1 from Toxoplasma gondii (TgCEN1). However, the molecular details of the interaction between TgCEN1 and TgSFI1 remain largely unknown. Herein, combining different biophysical methods, including isothermal titration calorimetry, nuclear magnetic resonance, circular dichroism, and fluorescence spectroscopy, we determined the binding properties of TgCEN1 and its individual N- and C-terminal domains to synthetic peptides derived from distinct repeats of TgSFI1. Overall, our data indicate that the repeats in TgSFI1 constitute binding sites for TgCEN1, but the binding modes of TgCEN1 to the repeats differ appreciably in terms of binding affinity, Ca2+ sensitivity, and lobe-specific interaction. These results suggest that TgCEN1 displays remarkable conformational plasticity, allowing for the distinct repeats in TgSFI1 to possess precise modes of TgCEN1 binding and regulation during Ca2+ sensing, which appears to be crucial for the dynamic association of TgCEN1 with TgSFI1 in the centrosome architecture.
    Keywords:  SFI1 protein; Toxoplasma gondii; calcium; centrin; protein-peptide interactions
  26. Brain Sci. 2022 Aug 08. pii: 1050. [Epub ahead of print]12(8):
      Toxoplasmosis is one of the most common opportunistic infections, mainly reported in patients with acquired immunodeficiency syndrome (AIDS). Patients with rheumatoid arthritis (RA) have also been linked to reactivation of toxoplasmosis due to immunosuppressive treatment, although biologic drugs have seldom been implicated. We present a case of cerebral toxoplasmosis in a 62-year-old female patient with RA after initiation of biologic therapy (adalimumab). The patient had detectable serum IgG antibodies to toxoplasma gondii, was also on chronic treatment with other non-biologic drugs and presented with worsening disorientation, unsteady gait and left hemiparesis. Imaging studies showed a space-occupying lesion in the right basal ganglia with ring-enhancement. Brain biopsy confirmed the diagnosis of toxoplasmosis and the patient was treated with pyrimethamine and sulfadiazine for 6 weeks, showing complete recovery on follow-up. A review of the literature yielded other four case reports of cerebral toxoplasmosis implying biologic drugs; however, data concerning toxoplasmosis serologic testing, prophylaxis and treatment in these patients are lacking. Each case must be carefully evaluated prior to treatment and a high-index of suspicion in seropositive patients is warranted. Since the use of biologic drugs is increasing, further research is needed to establish practical guidelines for seropositive patients receiving immunosuppressive treatment.
    Keywords:  adalimumab; biologic therapy; cerebral toxoplasmosis; rheumatoid arthritis
  27. J Biol Chem. 2022 Aug 22. pii: S0021-9258(22)00853-5. [Epub ahead of print] 102410
      NAD+ is a cellular redox cofactor involved in many essential processes. The regulation of NAD+ metabolism and the signaling networks reciprocally interacting with NAD+-producing metabolic pathways are not yet fully understood. The NAD+-dependent histone deacetylase (HDAC) Hst1 has been shown to inhibit de novo NAD+ synthesis by repressing biosynthesis of nicotinic acid (BNA) gene expression. Here, we alternatively identify HDAC Rpd3 as a positive regulator of de novo NAD+ metabolism in the budding yeast Saccharomyces cerevisiae. We reveal that deletion of RPD3 causes marked decreases in the production of de novo pathway metabolites, in direct contrast to deletion of HST1. We determined the BNA expression profiles of rpd3Δ and hst1Δ cells to be similarly opposed, suggesting the two HDACs may regulate the BNA genes in an antagonistic fashion. Our ChIP analysis revealed Rpd3 and Hst1 mutually influence each other's binding distribution at the BNA2 promoter. We demonstrate Hst1 to be the main deacetylase active at the BNA2 promoter, with hst1Δ cells displaying increased acetylation of the N-terminal tail lysine residues of histone H4, H4K5 and H4K12. Conversely, we show that deletion of RPD3 reduces the acetylation of these residues in a Hst1-dependent manner. This suggests Rpd3 may function to oppose spreading of Hst1-dependent heterochromatin and represents a unique form of antagonism between HDACs in regulating gene expression. Moreover, we found that Rpd3 and Hst1 also co-regulate additional targets involved in other branches of NAD+ metabolism. These findings help elucidate the complex interconnections involved in effecting the regulation of NAD+ metabolism.
    Keywords:  NAD(+) biosynthesis; cell metabolism; gene regulation; histone deacetylase; metabolic regulation; yeast genetics; yeast metabolism