Calcium Signaling Throughout the Toxoplasma gondii Lytic Cycle. A Study Using Genetically Encoded Calcium Indicators

J Biol Chem. 2015 Sep 15. pii: jbc.M115.652511. [Epub ahead of print]

 

Borges-Pereira L¹, Budu A¹, McKnight CA¹, Moore CA¹, Vella SA¹, Hortua Triana MA¹, Liu J¹, Garcia CR¹, Pace DA¹, Moreno SN².

 

Toxoplasma gondii is an obligate intracellular parasite that invades host cells, creating a parasitophorous vacuole (PV) where it communicates with the host cell cytosol through the PV 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 Ca2+ oscillations occur in the cytosol of the parasite during egress, gliding, and invasion, critical steps of the lytic cycle. Extracellular Ca2+ 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 measured Ca2+ changes in both parasites and host simultaneously during egress. We demonstrated a link between cytosolic Ca2+ 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 Ca2+ influx. This is the first study showing, in real time, Ca2+ signals preceding egress and their direct link with motility, an essential virulence trait.
Copyright © 2015, The American Society for Biochemistry and Molecular Biology.

KEYWORDS:

GCaMP; Gliding; Lytic cycle; Toxoplasma gondii; calcium; calcium imaging; host-pathogen interaction; signaling

PMID:

26374900

[PubMed - as supplied by publisher]