title: Calcium Signaling throughout the Toxoplasma gondii Lytic Cycle: A STUDY USING GENETICALLY ENCODED CALCIUM INDICATORS.
abstract: Toxoplasma gondii is an obligate intracellular parasite that invades host cells, creating a parasitophorous vacuole where it communicates with the host cell cytosol through the parasitophorous vacuole membrane. The lytic cycle of the parasite starts with its exit from the host cell followed by gliding motility, conoid extrusion, attachment, and invasion of another host cell. Here, we report that Ca(2+) oscillations occur in the cytosol of the parasite during egress, gliding, and invasion, which are critical steps of the lytic cycle. Extracellular Ca(2+) enhances each one of these processes. We used tachyzoite clonal lines expressing genetically encoded calcium indicators combined with host cells expressing transiently expressed calcium indicators of different colors, and we measured Ca(2+) changes in both parasites and host simultaneously during egress. We demonstrated a link between cytosolic Ca(2+) oscillations in the host and in the parasite. Our approach also allowed us to measure two new features of motile parasites, which were enhanced by Ca(2+) influx. This is the first study showing, in real time, Ca(2+) signals preceding egress and their direct link with motility, an essential virulence trait.
authors.affiliation: Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia 30602.
authors.forename: Lucas
authors.initials: L
authors.lastname: Borges-Pereira
authors.affiliation: Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia 30602.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Budu
authors.affiliation: Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia 30602.
authors.forename: Ciara A
authors.initials: CA
authors.lastname: McKnight
authors.affiliation: Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia 30602; Department of Cellular Biology, University of Georgia, Athens, Georgia 30602.
authors.forename: Christina A
authors.initials: CA
authors.lastname: Moore
authors.affiliation: Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia 30602.
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Vella
authors.affiliation: Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia 30602.
authors.forename: Miryam A
authors.initials: MA
authors.lastname: Hortua Triana
authors.affiliation: Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia 30602.
authors.forename: Jing
authors.initials: J
authors.lastname: Liu
authors.affiliation: Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia 30602.
authors.forename: Celia R S
authors.initials: CRS
authors.lastname: Garcia
authors.affiliation: Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia 30602.
authors.forename: Douglas A
authors.initials: DA
authors.lastname: Pace
authors.affiliation: Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia 30602; Department of Cellular Biology, University of Georgia, Athens, Georgia 30602. Electronic address: smoreno@uga.edu.
authors.forename: Silvia N J
authors.initials: SNJ
authors.lastname: Moreno
mesh_terms: D000818:Animals; D061207:Calcium Ionophores / Q000494:pharmacology; D020013:Calcium Signaling / Q000187:drug effects / Q000235:genetics; D002460:Cell Line; D006367:HeLa Cells; D006790:Host-Parasite Interactions / Q000235:genetics / Q000502:physiology; D006801:Humans; D015759:Ionomycin / Q000494:pharmacology; D008164:Luminescent Proteins / Q000235:genetics; D011994:Recombinant Proteins / Q000235:genetics; D014122:Toxoplasma / Q000235:genetics / Q000472:pathogenicity / Q000502:physiology*; D014162:Transfection; D014774:Virulence
chemical_list: D061207:Calcium Ionophores; D008164:Luminescent Proteins; D011994:Recombinant Proteins; D015759:Ionomycin
keywords: GCaMP; Toxoplasma gondii; calcium; calcium imaging; gliding; host-pathogen interaction; lytic cycle; signaling