Characterization of a Toxoplasma effector uncovers an alternative GSK3/β-catenin-regulatory pathway of inflammation
- University of Grenoble Alpes, Inserm, CNRS, IAB, France
- CEA, Inserm, BIG-BGE, France
Figures
Figure 1
GRA18 is secreted and exported to the host cell cytoplasm.
(A) Alignment of GRA18 alleles from T. gondii strains of types I (TGGT1_288840), II (TGME49_288840), and III (TGVEG_288840). The signal peptide sequence (highlighted in green), the B56 SLiM motifs …
Figure 2 with 1 supplement
GRA18 binds directly to the host cell proteins β-catenin, GSK3α/β, and PP2A-B56.
(A) Yeast-two hybrid screening of a human placental cDNA library to identify potential host partners for GRA18. Schematic representation of the identified partners having the highest Global PBS …
Figure 2—figure supplement 1
Summary of the hits in the Y2H screen against GRA18.
Each grey line indicates a single hit in the screen, and the red segments indicate the minimal fragment of each protein that is predicted to interact with GRA18.
Figure 3
β-Catenin, GSK3, and PP2A-B56 recognize distinct domains of GRA18.
(A) Interaction domain mapping by Y2H assay using the indicated fragments of GRA18 to delineate the interacting domains of GRA18 with CTNBB1 (β-catenin), GSK3A (GSK3α) and PPP2R5A (PP2A-B56α). …
Figure 4
GRA18 is a positive regulator β-catenin.
(A) Generation and confirmation of insertion/deletion of GRA18 in T. gondii type II Pru strain. Schematic representation of the GRA18 locus with the double homologous recombination event between the …
Figure 5 with 2 supplements
GRA18 alters the host cell transcriptome.
(A) RNA-Seq analysis of BALB/c BMDMs that were left uninfected (ui) or infected with the indicated strains at an MOI of 1:5. At 18 hr post-infection, cells were left unstimulated or stimulated with …
Figure 5—figure supplement 1
RNA-Seq analysis of mouse and T.
gondii transcripts. (A) T. gondii RNA-Seq analysis at the GRA18 genomic locus. Coverage track of the T. gondii RNA-Seq reads for the indicated samples obtained from GenVision Pro, Lasergene version …
Figure 5—figure supplement 2
Deletion of the aspartyl protease ASP5 compromises GRA18 export and phenocopies the deletion of GRA18 in promoting host cell gene expression.
(A) In the absence of ASP5, GRA18-HF transiently transfected in type I parasites was no longer exported to the host cytoplasm and instead remained within the PV. (B) In the absence of ASP5, T. gondii…
Figure 6
GRA18 promotes Ccl17, Ccl22 and Ccl24 chemokines expression in a β-catenin-dependent fashion.
(A) Schematic diagram of gRNAs targeting the Ctnnb1 locus. The Protospacer Adjacent Motif (PAM) sequence is lined and highlighted in red; the targeting sequences is shown in green. Bi-directional …
Figure 7
GRA18 activity is dependent on its interactions with GSK3 and PP2A-B56.
(A–B) RAW264.7 cells were transfected with mCherry vector control or the FH-GRA18 expression vectors pcDNA-FH-GRA18FL (GRA18FL), pcDNA-FH-GRA18Nt (GRA18Nt), and pcDNA-FH-GRA18Ct (GRA18Ct). At 18 hr …
Figure 8
Model for GRA18 mechanism of action.
A model depicting how GRA18 interacts and interferes with the β-catenin destruction complex leading to host cell gene regulation. Possible effect of GRA18 on gene expression through GSK3 but …
Author response image 1
qRT-PCR analysis of MAF-DKO macrophages (low passages) infected by the indicated strains of T. gondii at a MOI of 1:6.
Author response image 2
qRT-PCR analysis of MAF-DKO macrophages (high passages, after lentiviral transductions) infected by the indicated strains of T. gondii at a MOI of 1:6.
Additional files
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Supplementary file 1
Strains and Plasmids, Primers and oligonucleotides.
- https://doi.org/10.7554/eLife.39887.013
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Supplementary file 2
Y2H screen results.
- https://doi.org/10.7554/eLife.39887.014
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Supplementary file 3
Gene expression profiles in BMDMs and T. gondii with and without LPS stimulation.
RNA-Seq Reads Mouse. Summary of total RNASeq reads and average reads mapped to the mouse genome. RNA-Seq Reads Toxoplasma. Summary of total RNASeq reads and average reads mapped to the Toxoplasma genome. RPKM values for BMDMs. Expression values for all the mouse genes in the indicated samples. RPKM and log2 transformed values are shown. RPKM values for T. gondii. Expression values for all the Toxoplasma genes in the indicated samples. RPKM and log2 transformed values are shown. Pru vs gra18. RPKM values of the BMDM genes differentially regulated between the wild-type (Pru ku80) and gra18 mutant strains. Genes that were modulated with more than three-fold change and having a signal threshold above 5 RPKM in at least one sample when comparing the wild-type and Δgra18 mutant strains are shown. RPKM and log2 transformed values are shown for the indicated samples. ui vs ui_LPS. RPKM values of the BMDM genes differentially regulated between uninfected BMDMs that were left unstimulated (ui) or stimulated with LPS for 4 hr (ui_LPS). Genes that were modulated with more than three-fold change and having a signal threshold above 5 RPKM in at least one sample when comparing the ui and ui_LPS samples are shown. RPKM and log2 transformed values are shown for the indicated samples. β-Catenin target genes. RPKM values of known β-catenin/TCF target genes in the RNA-Seq experiment presented in Figure 5. Some direct target genes defined as those with Tcf binding sites are indicated in red. ui vs Pru. RPKM values of the BMDM genes differentially regulated when comparing BMDM left uninfected (ui) and BMDM infected by wild-type parasites (Pru) in the absence of LPS stimulation. Genes that were modulated with more than three-fold change and having a signal threshold above 5 RPKM in at least one sample when comparing the ui and Pru samples are shown. RPKM and log2 transformed values are shown for the indicated samples.
- https://doi.org/10.7554/eLife.39887.015
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Transparent reporting form
- https://doi.org/10.7554/eLife.39887.016
