Calcium Entry in Toxoplasma gondii and its Enhancing Effect of Invasion-linked Traits

Pace DA¹, Mcknight CA¹, Liu J², Jimenez V¹, Moreno SN³.

Abstract

During invasion and egress from their host cells Apicomplexan parasites face sharp changes in the surrounding calcium ion (Ca2+) concentration. Our work with Toxoplasma gondii provides evidence for Ca2+ influx from the extracellular milieu leading to cytosolic Ca2+ increase and enhancement of virulence traits, such as gliding motility, conoid extrusion, microneme secretion, and host cell invasion. Assays of Mn2+ and Ba2+ uptake do not support a canonical store regulated Ca2+ entry mechanism. Ca2+ entry was blocked by the L-type Ca2+ channel inhibitor nifedipine and stimulated by the increase in cytosolic Ca2+ and by the specific L-type Ca2+ channel agonist Bay K-8644. Our results demonstrate that Ca2+ entry is critical for parasite virulence. We propose a regulated Ca2+ entry mechanism activated by cytosolic Ca2+ that has an enhancing effect on invasion-linked traits.
Copyright © 2014, The American Society for Biochemistry and Molecular Biology.

KEYWORDS:

Conoid Extrusion; Gliding motility; Toxoplasma gondii; calcium; cell invasion; fluorescence; nifedipine; parasite; protozoan; signaling

PMID:: 24867952; [PubMed - as supplied by publisher]

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