Characterization of Ca2 transport activity associated with a non‐mitochondrial calcium pool in the rodent malaria parasite P. chabaudi

Passos, Ana Paula Pereira dos; Garcia, Célia Regina da Silva

doi:10.1080/15216549700203361

Cited by 18 publications

(22 citation statements)

References 10 publications

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“…To investigate the source of the observed Ca 2+ oscillations, we depleted Ca 2+ stores before imaging by using thapsigargin (Tg), a specific inhibitor of sarco/endoplasmic reticulum Ca 2+ –ATPase, and concanamycin A (CMA), a specific inhibitor of vacuolar-type H + -ATPase. The effects of these inhibitors have been demonstrated in Plasmodium species [28]–[30]. We also confirmed the effectiveness of these compounds in depleting Ca 2+ by Ca 2+ imaging in early ring forms and early trophozoites using perfusion experiments (Fig.…”

Section: Resultssupporting

confidence: 80%

Blockage of Spontaneous Ca2+ Oscillation Causes Cell Death in Intraerythrocitic Plasmodium falciparum

et al. 2012

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Malaria remains one of the world’s most important infectious diseases and is responsible for enormous mortality and morbidity. Resistance to antimalarial drugs is a challenging problem in malaria control. Clinical malaria is associated with the proliferation and development of Plasmodium parasites in human erythrocytes. Especially, the development into the mature forms (trophozoite and schizont) of Plasmodium falciparum (P. falciparum) causes severe malaria symptoms due to a distinctive property, sequestration which is not shared by any other human malaria. Ca2+ is well known to be a highly versatile intracellular messenger that regulates many different cellular processes. Cytosolic Ca2+ increases evoked by extracellular stimuli are often observed in the form of oscillating Ca2+ spikes (Ca2+ oscillation) in eukaryotic cells. However, in lower eukaryotic and plant cells the physiological roles and the molecular mechanisms of Ca2+ oscillation are poorly understood. Here, we showed the observation of the inositol 1,4,5-trisphospate (IP3)-dependent spontaneous Ca2+ oscillation in P. falciparum without any exogenous extracellular stimulation by using live cell fluorescence Ca2+ imaging. Intraerythrocytic P. falciparum exhibited stage-specific Ca2+ oscillations in ring form and trophozoite stages which were blocked by IP3 receptor inhibitor, 2-aminoethyl diphenylborinate (2-APB). Analyses of parasitaemia and parasite size and electron micrograph of 2-APB-treated P. falciparum revealed that 2-APB severely obstructed the intraerythrocytic maturation, resulting in cell death of the parasites. Furthermore, we confirmed the similar lethal effect of 2-APB on the chloroquine-resistant strain of P. falciparum. To our best knowledge, we for the first time showed the existence of the spontaneous Ca2+ oscillation in Plasmodium species and clearly demonstrated that IP3-dependent spontaneous Ca2+ oscillation in P. falciparum is critical for the development of the blood stage of the parasites. Our results provide a novel concept that IP3/Ca2+ signaling pathway in the intraerythrocytic malaria parasites is a promising target for antimalarial drug development.

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Section: Resultssupporting

confidence: 80%

Blockage of Spontaneous Ca2+ Oscillation Causes Cell Death in Intraerythrocitic Plasmodium falciparum

et al. 2012

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“…The digestion of the Hb takes place at the food vacuole, and it has been suggested that this organelle is the acidic compartment where antimalarial drugs such as chloroquine are accumulated (Yayon et al, 1984) and prevents haemozoin polymerization (Goldberg and Slater, 1992). However, this compartment also accumulates Ca 2+ in human and rodent malaria parasites (Passos and Garcia, 1997; Garcia et al, 1998; Marchesini et al, 2000; Varotti et al, 2003; Rohrbach et al, 2005; Bagnaresi et al, 2009). Calcium handling mechanisms in these organisms have been extensively studied by several authors (Wasserman, 1990; Adovelande et al, 1993; Hotta et al, 2000; Beraldo et al, 2005; Sartorello et al, 2009).…”

Section: Discussionmentioning

confidence: 99%

In vivo uptake of a haem analogue Zn protoporphyrin IX by the human malaria parasite P. falciparum‐infected red blood cells

Sartorello

Budu²,

Bagnaresi

et al. 2010

Cell Biology International

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The cellular traffic of haem during the development of the human malaria parasite Plasmodium falciparum, through the stages R (ring), T (trophozoite) and S (schizonts), was investigated within RBC (red blood cells). When Plasmodium cultures were incubated with a fluorescent haem analogue, ZnPPIX (Zn protoporphyrin IX) the probe was seen at the cytoplasm (R stage), and the vesicle-like structure distribution pattern was more evident at T and S stages. The temporal sequence of ZnPPIX uptake by P. falciparum-infected erythrocytes shows that at R and S stages, a time-increase acquisition of the porphyrin reaches the maximum fluorescence distribution after 60 min; in contrast, at the T stage, the maximum occurs after 120 min of ZnPPIX uptake. The difference in time-increase acquisition of the porphyrin is in agreement with a maximum activity of haem uptake at the T stage. To gain insights into haem metabolism, recombinant PfHO (P. falciparum haem oxygenase) was expressed, and the conversion of haem into BV (biliverdin) was detected. These findings point out that, in addition to haemozoin formation, the malaria parasite P. falciparum has evolved two distinct mechanisms for dealing with haem toxicity, namely, the uptake of haem into a cellular compartment where haemozoin is formed and HO activity. However, the low Plasmodium HO activity detected reveals that the enzyme appears to be a very inefficient way to scavenge the haem compared with the Plasmodium ability to uptake the haem analogue ZnPPIX and delivering it to the food vacuole.

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“…There are three Ca 2+ compartments in malaria parasite: endoplasmic reticulum (ER) (Passos & Garcia ), acidic compartment (Varotti et al . ) and mitochondrion (Gazarini & Garcia ).…”

Section: Resultsmentioning

confidence: 99%

Investigation of antimalarial activity, cytotoxicity and action mechanism of piperazine derivatives of betulinic acid

Silva

Schuck²,

Cruz³

et al. 2014

Tropical Med Int Health

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Abstractobjectives To semisynthesise piperazine derivatives of betulinic acid to evaluate antimalarial activity, cytotoxicity and action mechanism.methods The new derivatives were evaluated against the CQ-sensitive Plasmodium falciparum 3D7 strain by flow cytometry (FC) using YOYO-1 as stain. Cytotoxicity of 4a and 4b was performed with HEK293T cells for 24 and 48 h by MTT assay. The capability of compound 4a to modulate Ca 2+ in the trophozoite stage was investigated. The trophozoites were stained with Fluo4-AM and analysed by spectrofluorimetry. Effect on mitochondrial membrane potential (DΨm) was tested for 4a by FC with DiOC 6 (3) as stain. For b-haematin assay, 4a was incubated for 24 h with reagents such as haemin, and the fluorescence was measured by FlexStation at an absorbance of 405 nm.results Antimalarial activity of 4a and 4b was IC 50 = 1 and 4 lM, respectively. Compound 4a displayed cytotoxicity with IC 50 = 69 and 29 lM for 24 and 48 h, respectively, and 4b was not cytotoxic at the tested concentrations. Addition of 4a leads to an increase in cytosolic Ca 2+ . We have measured DΨm after treating parasites with the compound. Data on Figure 4a show that mitochondria were not affected. The action mechanism for 4a, inhibition of b-haematin formation (17%), was lower than CQ treatment (83%; IC 50 = 3 mM).conclusion Compound 4a showed excellent antimalarial activity, and its action mechanism is involved in Ca 2+ pathway(s).

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Characterization of Ca2 transport activity associated with a non‐mitochondrial calcium pool in the rodent malaria parasite P. chabaudi

Cited by 18 publications

References 10 publications

Blockage of Spontaneous Ca2+ Oscillation Causes Cell Death in Intraerythrocitic Plasmodium falciparum

Blockage of Spontaneous Ca2+ Oscillation Causes Cell Death in Intraerythrocitic Plasmodium falciparum

In vivo uptake of a haem analogue Zn protoporphyrin IX by the human malaria parasite P. falciparum‐infected red blood cells

Investigation of antimalarial activity, cytotoxicity and action mechanism of piperazine derivatives of betulinic acid

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