Submicrometre spatiotemporal characterization of the Toxoplasma adhesion strategy for gliding motility.

Toxoplasma gondii is a protozoan apicomplexan parasite that uses an adhesion-dependent mode of motility termed gliding to access host cells and disseminate into tissues. Previous studies on Apicomplexa motile morphotypes, including the T. gondii tachyzoite, have identified a cortical actin-myosin motor system that drives the rearward translocation of transmembrane adhesins, thus powering forward movement.

The BCC7 Protein Contributes to the Basal Pole by Interfacing between the MyoC Motor and the IMC Membrane Network.

is a eukaryotic parasite that has evolved a stage called tachyzoite which multiplies in host cells by producing two daughter cells internally. These nascent tachyzoites bud off their mother and repeat the division process until the expanding progenies escape to settle and multiply in other host cells. Over these intra- and extra-cellular phases, the tachyzoite maintains an essential apicobasal polarity that emerges through a unique bidirectional budding process of the elongating cells.

Profiling of myristoylation in reveals an -myristoylated protein important for host cell penetration.

-myristoylation is a ubiquitous class of protein lipidation across eukaryotes and -myristoyl transferase (NMT) has been proposed as an attractive drug target in several pathogens. Myristoylation often primes for subsequent palmitoylation and stable membrane attachment, however, growing evidence suggests additional regulatory roles for myristoylation on proteins. Here we describe the myristoylated proteome of using chemoproteomic methods and show that a small-molecule NMT inhibitor developed against related .

Coupling Polar Adhesion with Traction, Spring, and Torque Forces Allows High-Speed Helical Migration of the Protozoan Parasite .

Among the eukaryotic cells that navigate through fully developed metazoan tissues, protozoans from the Apicomplexa phylum have evolved motile developmental stages that move much faster than the fastest crawling cells owing to a peculiar substrate-dependent type of motility, known as gliding. Best-studied models are the sporozoite and the tachyzoite polarized cells for which motility is vital to achieve their developmental programs in the metazoan hosts. The gliding machinery is shared between the two parasites and is largely characterized.

Division and Adaptation to Host Environment of Apicomplexan Parasites Depend on Apicoplast Lipid Metabolic Plasticity and Host Organelle Remodeling.

Apicomplexan parasites are unicellular eukaryotic pathogens that must obtain and combine lipids from both host cell scavenging and de novo synthesis to maintain parasite propagation and survival within their human host. Major questions on the role and regulation of each lipid source upon fluctuating host nutritional conditions remain unanswered. Characterization of an apicoplast acyltransferase, TgATS2, shows that the apicoplast provides (lyso)phosphatidic acid, required for the recruitment of a critical dynamin (TgDrpC) during parasite cytokinesis.

Francisella novicida and F. philomiragia biofilm features conditionning fitness in spring water and in presence of antibiotics.

Biofilms are currently considered as a predominant lifestyle of many bacteria in nature. While they promote survival of microbes, biofilms also potentially increase the threats to animal and public health in case of pathogenic species. They not only facilitate bacteria transmission and persistence, but also promote spreading of antibiotic resistance leading to chronic infections.

The Toxoplasma effector TEEGR promotes parasite persistence by modulating NF-κB signalling via EZH2.

The protozoan parasite Toxoplasma gondii has co-evolved with its homeothermic hosts (humans included) strategies that drive its quasi-asymptomatic persistence in hosts, hence optimizing the chance of transmission to new hosts. Persistence, which starts with a small subset of parasites that escape host immune killing and colonize the so-called immune privileged tissues where they differentiate into a low replicating stage, is driven by the interleukin 12 (IL-12)-interferon-γ (IFN-γ) axis. Recent characterization of a family of Toxoplasma effectors that are delivered into the host cell, in which they rewire the host cell gene expression, has allowed the identification of regulators of the IL-12-IFN-γ axis, including repressors.

Specific Targeting of Plant and Apicomplexa Parasite Tubulin through Differential Screening Using In Silico and Assay-Based Approaches.

Dinitroanilines are chemical compounds with high selectivity for plant cell α-tubulin in which they promote microtubule depolymerization. They target α-tubulin regions that have diverged over evolution and show no effect on non-photosynthetic eukaryotes. Hence, they have been used as herbicides over decades.

High-content imaging assay to evaluate Toxoplasma gondii infection and proliferation: A multiparametric assay to screen new compounds.

Toxoplasma gondii is an intracellular protozoan parasite widely distributed in animals and humans. Infection of host cells and parasite proliferation are essential steps in Toxoplasma pathology. The objective of this study was to develop and validate a novel automatic High Content Imaging (HCI) assay to study T.

Toxoplasma Parasite Twisting Motion Mechanically Induces Host Cell Membrane Fission to Complete Invasion within a Protective Vacuole.

To invade cells, the parasite Toxoplasma gondii injects a multi-unit nanodevice into the target cell plasma membrane (PM). The core nanodevice, which is composed of the RhOptry Neck (RON) protein complex, connects Toxoplasma and host cell through a circular tight junction (TJ). We now report that this RON nanodevice mechanically promotes membrane scission at the TJ-PM interface, directing a physical rotation driven by the parasite twisting motion that enables the budding parasitophorous vacuole (PV) to seal and separate from the host cell PM as a bona fide subcellular Toxoplasma-loaded PV.

Targeting Prolyl-tRNA Synthetase to Accelerate Drug Discovery against Malaria, Leishmaniasis, Toxoplasmosis, Cryptosporidiosis, and Coccidiosis.

Developing anti-parasitic lead compounds that act on key vulnerabilities are necessary for new anti-infectives. Malaria, leishmaniasis, toxoplasmosis, cryptosporidiosis and coccidiosis together kill >500,000 humans annually. Their causative parasites Plasmodium, Leishmania, Toxoplasma, Cryptosporidium and Eimeria display high conservation in many housekeeping genes, suggesting that these parasites can be attacked by targeting invariant essential proteins.

Targeting CPSF3 as a new approach to control toxoplasmosis.

is an important food and waterborne pathogen causing toxoplasmosis, a potentially severe disease in immunocompromised or congenitally infected humans. Available therapeutic agents are limited by suboptimal efficacy and frequent side effects that can lead to treatment discontinuation. Here we report that the benzoxaborole AN3661 had potent activity against Parasites selected to be resistant to AN3661 had mutations in , which encodes a homologue of cleavage and polyadenylation specificity factor subunit 3 (CPSF-73 or CPSF3), an endonuclease involved in mRNA processing in eukaryotes.

Genetic impairment of parasite myosin motors uncovers the contribution of host cell membrane dynamics to Toxoplasma invasion forces.

Background: The several-micrometer-sized Toxoplasma gondii protozoan parasite invades virtually any type of nucleated cell from a warm-blooded animal within seconds. Toxoplasma initiates the formation of a tight ring-like junction bridging its apical pole with the host cell membrane. The parasite then actively moves through the junction into a host cell plasma membrane invagination that delineates a nascent vacuole.

Toxoplasma gondii TgIST co-opts host chromatin repressors dampening STAT1-dependent gene regulation and IFN-γ-mediated host defenses.

An early hallmark of Toxoplasma gondii infection is the rapid control of the parasite population by a potent multifaceted innate immune response that engages resident and homing immune cells along with pro- and counter-inflammatory cytokines. In this context, IFN-γ activates a variety of T. gondii-targeting activities in immune and nonimmune cells but can also contribute to host immune pathology.

Cryptosporidium and Toxoplasma Parasites Are Inhibited by a Benzoxaborole Targeting Leucyl-tRNA Synthetase.

The apicomplexan parasites Cryptosporidium and Toxoplasma are serious threats to human health. Cryptosporidiosis is a severe diarrheal disease in malnourished children and immunocompromised individuals, with the only FDA-approved drug treatment currently being nitazoxanide. The existing therapies for toxoplasmosis, an important pathology in immunocompromised individuals and pregnant women, also have serious limitations.

Structure of Prolyl-tRNA Synthetase-Halofuginone Complex Provides Basis for Development of Drugs against Malaria and Toxoplasmosis.

The Chinese herb Dichroa febrifuga has traditionally treated malaria-associated fever. Its active component febrifugine (FF) and derivatives such as halofuginone (HF) are potent anti-malarials. Here, we show that FF-based derivatives arrest parasite growth by direct interaction with and inhibition of the protein translation enzyme prolyl-tRNA synthetase (PRS).

AG11, a novel dichloroflavanone derivative with anti-mitotic activity towards human bladder cancer cells.

Background: New chemotherapy drugs should be investigated to improve survival of patients with advanced bladder cancer. Here, we report the synthesis and evaluation of AG11, a new flavanone derivative obtained through cyclization of its chalcone precursor CB11.

Materials And Methods: The effect of AG11 on cell viability was evaluated by 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide assay and apoptotic cell death was analyzed by flow cytometry.

Investigation of a new 1,3-diarylpropenone as a potential antimitotic agent targeting bladder carcinoma.

1-(2,4-dimethoxyphenyl)-3-(1-methylindolyl) propenone, namely IPP51, was identified by screening a library of 3-indolyl-1-phenylpropenones. IPP51 was investigated for its ability to inhibit proliferation and/or to induce apoptosis of human bladder cancer cell lines and to assess its potential use in bladder carcinoma treatment. After treating the cells with IPP51 for 24 h, the title compound induced a predominant and reversible G2+M accumulation at the prometaphase stage of mitosis.

Parturition in the rat: a physiological pain model.

Background: Pain during labor is a common and severe phenomenon, but its clinical management remains haphazard because its neurophysiology is poorly understood. In the current study, the authors evaluate the parturient rat as a relevant model to study the pharmacology of labor pain.

Methods: Control of birth timing in term pregnant rats was achieved by gavage with RU 486 (5 mg/kg) the day before the expected day of parturition.

Glia-derived D-serine controls NMDA receptor activity and synaptic memory.

The NMDA receptor is a key player in excitatory transmission and synaptic plasticity in the central nervous system. Its activation requires the binding of both glutamate and a co-agonist like D-serine to its glycine site. As D-serine is released exclusively by astrocytes, we studied the physiological impact of the glial environment on NMDA receptor-dependent activity and plasticity.