Dataset Information

MS-based proteomic characterization of Toxoplasma gondii GRA28-associated complexes

ABSTRACT: The obligate intracellular protozoan Toxoplasma gondii exploits the trafficking of mononuclear phagocytes for systemic dissemination. We report that, upon T. gondii infection, macrophages initiate expression of transcription factors normally attributed to DCs, upregulate the expression of Ccr7 with a chemotactic response, and perform systemic migration when adoptively transferred into mice. We identify the parasite effector GRA28, which is secreted into the host cell nuclei, as driving the chemotactic migratory activation of parasitized macrophages. To gain insight about the molecular role played by GRA28 in this phenomenon, we characterized its interactome.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Toxoplasma Gondii Rh Mus Musculus (mouse)

TISSUE(S): Macrophage

SUBMITTER: Yohann Couté

LAB HEAD: Yohann Couté

PROVIDER: PXD032360 | Pride | 2022-11-02

REPOSITORIES: pride

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The Toxoplasma effector GRA28 promotes parasite dissemination by inducing dendritic cell-like migratory properties in infected macrophages.

Ten Hoeve Arne L AL Braun Laurence L Rodriguez Matias E ME Olivera Gabriela C GC Bougdour Alexandre A Belmudes Lucid L Couté Yohann Y Saeij Jeroen P J JPJ Hakimi Mohamed-Ali MA Barragan Antonio A

Cell host & microbe 20221028 11

Upon pathogen detection, macrophages normally stay sessile in tissues while dendritic cells (DCs) migrate to secondary lymphoid tissues. The obligate intracellular protozoan Toxoplasma gondii exploits the trafficking of mononuclear phagocytes for dissemination via unclear mechanisms. We report that, upon T. gondii infection, macrophages initiate the expression of transcription factors normally attributed to DCs, upregulate CCR7 expression with a chemotactic response, and perform systemic migrati ...[more]

PMID: 36309013

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Project description:The phylum Apicomplexa comprises an ancient group of early divergent eukaryotes, including some of the most deadly pathogens of medical and veterinary importance. Plasmodium species are responsible for malaria, which causes as many as 700,000 deaths per year, while Toxoplasma gondii chronically infects up to 30% of the human population, with immunocompromised patients and pregnant women at risk for adverse outcomes, such as toxoplasmic encephalitis and spontaneous abortion, respectively. T. gondii is considered a model system not only for its pathogenic relatives but also for intracellular parasitism and infection biology in general. T. gondii has common eukaryotic organelles, including the nucleus, endoplasmic reticulum (ER), and a single Golgi stack, but also specific secretory organelles named dense granules, micronemes, and rhoptries that contain parasite-derived factors required for host infection. Rhoptries and micronemes are formed de novo during parasite replication, and this process requires significant protein and lipid trafficking through the secretory pathway. The trafficking mechanisms employed by T. gondii retain several typical eukaryote components as well as evolving divergent features. Protein trafficking of this parasite is mediated by entry into a canonical ER followed by vesicle packaging through a single Golgi complex. Post-Golgi protein sorting to specific organelles requires the function of dynamin-related protein B, which is involved in fission events. Downstream Rab-GTPases function throughout the parasite secretory pathway. T. gondii soluble N-ethylmaleimide-sensitive-factor attachment protein receptor (SNARE) proteins in docking and fusion at target membranes have also been described. However, unlike in mammalian cells, T. gondii ER is reduced so that the nuclear envelope itself contributes to a substantial proportion of its total volume. Whereas in mammalian cells hundreds of Golgi stacks occupy the perinuclear area, the Golgi apparatus is limited to a single discrete structure in T.gondii. The post-Golgi system also named the endosome-like compartment (ELC) is involved in the trafficking of microneme proteins. The ELC is decorated by the small GTPases, Rab5 and Rab7, which are typically associated with the endosomal system. Nevertheless, classical endocytosis has not yet been validated in T. gondii. This parasite has no lysosomes; rather the parasite harbors acidic vesicles that were thought to be precursors of the rhoptry organelles. The parasite lacks most components of endosomal sorting complexes (ESCRT), which are known for their roles in forming multivesicular bodies that deliver ubiquitinated membrane proteins and lipids to lysosomes for degradation. The machinery required for caveogenesis and caveola-dependent invaginations have not yet been identified in the parasite. Furthermore, while evidence of conventional clathrin-dependent endocytosis by T.gondii is lacking, clathrin is present exclusively in post-Golgi compartments where its function is restricted to post-Golgi trafficking, and the uptake of cytosol proteins by the tachyzoites of T. gondii has recently been described using an endocytosis assay. However, the mechanisms underlying the events of this unconventional endocytosis in the parasite remain to be determined. Clearly, the secretory pathway of T. gondii can be considered a stripped-down version of the more complex trafficking machinery that characterizes higher eukaryotes. Despite this minimal trafficking machinery, the parasites actively rely on a membrane vesicle formation and transport during its intracellular lifecycle; however, to date, comparatively little is known about the mechanisms involved in trafficking pathways in T. gondii. We previously reported a T. gondii sortilin-like receptor (TgSORTLR) that regulates protein transport and is essential for apical secretory organelle biogenesis and host infection17. Moreover, the C-terminal tail of TgSORTLR was shown to be involved in recruiting many cytosolic cargo proteins including two homologues of the core retromer components, Vps26 and Vps35, which are known to regulate retrograde transport from endosomes to the trans-Golgi Network (TGN) in yeast and mammals. Here, we report that a singular architecture with a trimer Vps35-Vps26-Vps29 core complex acts as the major cargo endosomal recycling machinery and is required for parasite integrity and more specifically for secretory organelle biogenesis and maintenance of a multiple ligand-binding transporter at the T. gondii membrane. Our findings provide strong evidence that the unconventional TgSORTLR-containing endosome-like compartment is involved in distinct mechanisms for the delivery of major retromer-dependent cargo. In this current work, we demonstrate a definitive role for the endocytic recycling pathway in T. gondii pathogenesis.

Project description:Intracellular pathogens including the apicomplexan and opportunistic parasite Toxoplasma gondii profoundly modify their host cells in order to establish infection. We have shown previously that intracellular T. gondii inhibit up-regulation of regulatory and effector functions in murine macrophages (MΦ) stimulated with interferon (IFN)-γ, which is the cytokine crucial for controlling the parasites’ replication. Using genome-wide transcriptome analysis we show herein that infection with T. gondii leads to global unresponsiveness of murine macrophages to IFN-γ. More than 61% and 89% of the transcripts, which were induced or repressed by IFN-γ in non-infected MΦ, respectively, were not altered after stimulation of T. gondii-infected cells with IFN-γ. These genes are involved in a variety of biological processes, which are mostly but not exclusively related to immune responses. Analyses of the underlying mechanisms revealed that IFN-γ-triggered nuclear translocation of STAT1 still occurred in Toxoplasma-infected MΦ. However, STAT1 bound aberrantly to oligonucleotides containing the IFN-γ-responsive gamma-activated site (GAS) consensus sequence. Conversely, IFN-γ did not induce formation of active GAS-STAT1 complexes in nuclear extracts from infected MΦ. Mass spectrometry of protein complexes bound to GAS oligonucleotides showed that T. gondii-infected MΦ are unable to recruit non-muscle actin to IFN-γ-responsive DNA sequences, which appeared to be independent of stimulation with IFN-γ and of STAT1 binding. IFN-γ-induced recruitment of BRG-1 and acetylation of core histones at the IFN-γ-regulated CIITA promoter IV, but not β-actin was diminished by >90% in Toxoplasma-infected MΦ as compared to non-infected control cells. Remarkably, treatment with histone deacetylase inhibitors restored the ability of infected macrophages to express the IFN-γ regulated genes H2-A/E and CIITA. Taken together, these results indicate that Toxoplasma-infected MΦ are unable to respond to IFN-γ due to disturbed chromatin remodelling, but can be rescued using histone deacetylase inhibitors. Comparison of 4 different RNA pools with a 2-Color-Loop Design including 10 microarrays: [1] T. gondii infected and IFN-gamma treated, [2] T. gondii infected and untreated, [3] Non-infected and IFN-gamma treated, and [4] Non-infected and untreated.

			Action	DRS
	F14-19.mgf	Mgf
	F14-19.raw	Raw
	F20-22.mgf	Mgf
	F20-22.raw	Raw
	GRA28-Interactome.mzid.gz	Mzid