title: Toxoplasma gondii-induced activation of EGFR prevents autophagy protein-mediated killing of the parasite.
abstract: Toxoplasma gondii resides in an intracellular compartment (parasitophorous vacuole) that excludes transmembrane molecules required for endosome-lysosome recruitment. Thus, the parasite survives by avoiding lysosomal degradation. However, autophagy can re-route the parasitophorous vacuole to the lysosomes and cause parasite killing. This raises the possibility that T. gondii may deploy a strategy to prevent autophagic targeting to maintain the non-fusogenic nature of the vacuole. We report that T. gondii activated EGFR in endothelial cells, retinal pigment epithelial cells and microglia. Blockade of EGFR or its downstream molecule, Akt, caused targeting of the parasite by LC3(+) structures, vacuole-lysosomal fusion, lysosomal degradation and killing of the parasite that were dependent on the autophagy proteins Atg7 and Beclin 1. Disassembly of GPCR or inhibition of metalloproteinases did not prevent EGFR-Akt activation. T. gondii micronemal proteins (MICs) containing EGF domains (EGF-MICs; MIC3 and MIC6) appeared to promote EGFR activation. Parasites defective in EGF-MICs (MIC1 ko, deficient in MIC1 and secretion of MIC6; MIC3 ko, deficient in MIC3; and MIC1-3 ko, deficient in MIC1, MIC3 and secretion of MIC6) caused impaired EGFR-Akt activation and recombinant EGF-MICs (MIC3 and MIC6) caused EGFR-Akt activation. In cells treated with autophagy stimulators (CD154, rapamycin) EGFR signaling inhibited LC3 accumulation around the parasite. Moreover, increased LC3 accumulation and parasite killing were noted in CD154-activated cells infected with MIC1-3 ko parasites. Finally, recombinant MIC3 and MIC6 inhibited parasite killing triggered by CD154 particularly against MIC1-3 ko parasites. Thus, our findings identified EGFR activation as a strategy used by T. gondii to maintain the non-fusogenic nature of the parasitophorous vacuole and suggest that EGF-MICs have a novel role in affecting signaling in host cells to promote parasite survival.
authors.affiliation: Department of Pathology, Case Western Reserve University, Cleveland, Ohio, United States of America ; Division of Infectious Diseases and HIV Medicine, Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America.
authors.forename: Luis
authors.initials: L
authors.lastname: Muniz-Feliciano
authors.affiliation: Department of Pathology, Case Western Reserve University, Cleveland, Ohio, United States of America ; Division of Infectious Diseases and HIV Medicine, Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Van Grol
authors.affiliation: Division of Infectious Diseases and HIV Medicine, Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America.
authors.forename: Jose-Andres C
authors.initials: JA
authors.lastname: Portillo
authors.affiliation: Division of Molecular Biosciences, Imperial College London, London, United Kingdom.
authors.forename: Lloyd
authors.initials: L
authors.lastname: Liew
authors.affiliation: Division of Molecular Biosciences, Imperial College London, London, United Kingdom.
authors.forename: Bing
authors.initials: B
authors.lastname: Liu
authors.affiliation: Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America.
authors.forename: Cathleen R
authors.initials: CR
authors.lastname: Carlin
authors.affiliation: Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America.
authors.forename: Vern B
authors.initials: VB
authors.lastname: Carruthers
authors.affiliation: Division of Molecular Biosciences, Imperial College London, London, United Kingdom.
authors.forename: Stephen
authors.initials: S
authors.lastname: Matthews
authors.affiliation: Department of Pathology, Case Western Reserve University, Cleveland, Ohio, United States of America ; Division of Infectious Diseases and HIV Medicine, Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America ; Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, Ohio, United States of America.
authors.forename: Carlos S
authors.initials: CS
authors.lastname: Subauste
mesh_terms: D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000502:physiology; D001343:Autophagy / Q000502:physiology*; D000071193:Autophagy-Related Protein 7; D000071186:Beclin-1; D016466:CHO Cells; D002478:Cells, Cultured; D006224:Cricetinae; D003412:Cricetulus; D004789:Enzyme Activation; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000502:physiology; D051379:Mice; D051058:Oncogene Protein v-akt / Q000378:metabolism; D014122:Toxoplasma / Q000276:immunology / Q000502:physiology*; D014123:Toxoplasmosis / Q000201:enzymology* / Q000235:genetics / Q000276:immunology; D044764:Ubiquitin-Activating Enzymes / Q000502:physiology
chemical_list: D051017:Apoptosis Regulatory Proteins; C491997:BECN1 protein, human; D000071186:Beclin-1; D008565:Membrane Proteins; C512478:EGFR protein, human; D066246:ErbB Receptors; D051058:Oncogene Protein v-akt; C509349:ATG7 protein, human; D000071193:Autophagy-Related Protein 7; D044764:Ubiquitin-Activating Enzymes