Calcium Entry in Toxoplasma gondii and Its Enhancing Effect of Invasion-linked Traits |
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| Authors: | Douglas A Pace Ciara A McKnight Jing Liu Veronica Jimenez Silvia N J Moreno |
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| Institution: | From the ‡Center for Tropical and Emerging Global Diseases and ;the §Department of Cellular Biology, University of Georgia, Athens, Georgia 30602 and ;the ¶College of Veterinary Medicine, China Agricultural University, Beijing 100193, China |
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| 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. |
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| Keywords: | Calcium Cell Invasion Fluorescence Parasite Protozoan Signaling Conoid Extrusion Gliding Motility Toxoplasma gondii Nifedipine |
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