Intracellular Ca2+ Signaling in Protozoan Parasites: An Overview with a Focus on Mitochondria

Abstract

Ca²⁺ signaling has been involved in controling critical cellular functions such as activation of proteases, cell death, and cell cycle control. The endoplasmatic reticulum plays a significant role in Ca²⁺ storage inside the cell, but mitochondria have long been recognized as a fundamental Ca²⁺ pool. Protozoan parasites such as Plasmodium falciparum, Toxoplasma gondii, and Trypanosoma cruzi display a Ca²⁺ signaling toolkit with similarities to higher eukaryotes, including the participation of mitochondria in Ca²⁺-dependent signaling events. This review summarizes the most recent knowledge in mitochondrial Ca²⁺ signaling in protozoan parasites, focusing on the mechanism involved in mitochondrial Ca²⁺ uptake by pathogenic protists.

Keywords: calcium signaling; mitochondria; protozoan parasites.

Figure 1

Fluorescent microscopy Plasmodium falciparum ring, trophozoites, and schizonts stages using a mitochondrial green fluorescent protein (GFP) construction: the parasite nucleus was stained by HOECHST33342 (blue) and mitochondria with MitoTracker Red CMX Ros (red) to demonstrate co-localization with Mito-Emerald-GFP (green) (A). P. chabaudi parasites were stained with Fluo4 (cytoplasmatic calcium indicator) and Rhod2 (mitochondrial calcium indicator): effect of melatonin (MLT) and thapsigargin (Thg) on Ca²⁺ (B); addition of thapsigargin (C); effect of melatonin and thapsigargin on Ca²⁺ fluorescence in the presence of FCCP (D); addition of thapsigargin in the presence of FCCP (E). Traces represent fluorescence intensity ratio of Ca²⁺ probes Rhod-2 AM-mitochondria (open circles) and Fluo-3 AM-cytosol (fill squares). The images were retrieved with the author’s consent from the following references: [84] (A) and [83] (B–E).