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bioRxiv · 10.1101/2020.03.06.980508

The Role of Host Calcium Signaling in Toxoplasma gondii egress

Vella, S. A.·Moore, C. A.·Li, Z.-H.·Hortua Triana, M. A.·Potapenko, E.·Moreno, S. N.
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Abstract

Toxoplasma gondii, an obligate intracellular parasite, is capable of invading virtually any nucleated cell. Ca2+ signaling is universal and both T. gondii and its mammalian host cell will utilize Ca2+ signaling to stimulate diverse cellular functions. Egress of T. gondii from the host cell is an essential step for the infection cycle of T. gondii and a cytosolic Ca2+ increase initiates the Ca2+ signaling cascade that culminates in stimulation of motility and egress. In this work we demonstrate that intracellular T. gondii is capable of taking up Ca2+ from the host cytoplasm when this concentration is increased during host signaling events. Both intracellular and extracellular Ca2+ sources are important to reach a threshold of cytosolic Ca2+ needed for a successful egress. Two peaks of Ca2+ were observed in single parasites that egressed with the second peak resulting from Ca2+ influx. We patched infected host cells to allow a precise delivery of exact concentrations of Ca2+ for stimulating motility and egress. Using this approach, we found that low potassium concentration modulates but do not trigger host cell egress. This is the first study using whole-cell patches to study the role of ions such as K+ and Ca2+ in T. gondii egress.

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Vella, S. A., Moore, C. A., Li, Z.-H., Hortua Triana, M. A., Potapenko, E., Moreno, S. N.. 2020-03-06. The Role of Host Calcium Signaling in Toxoplasma gondii egress. https://doi.org/10.1101/2020.03.06.980508

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