The role of calcium in the activation of the FIS1 and DRP1 genes in the mitochondrial division in P. falciparum (WT) and in the PfPK7 kinase knockout parasite

Malaria is an endemic disease in several tropical countries that is caused by a parasite of the phylum apicomplexa (Plasmodium) and transmitted by the bite of mosquitoes of the genus Anopheles. In humans, the most severe form of the disease is caused by Plasmodium falciparum. The disease kills 2 to 3 million people annually; mortality is so high that it is considered the highest among parasitic diseases (Snow, Guerra et al. 2005). Obtaining new drugs is necessary, since resistant parasites have already been observed for all known antimalarial drugs, so research to better understand the biology of the parasite is necessary to develop effective drugs and vaccines to fight the disease (Mita and Tanabe, 2012). The parasite’s life cycle occurs in two hosts: one vertebrate and one invertebrate. Thus, Plasmodium proves to be a parasite capable of perceiving the microenvironment and has mechanisms that enable it to use intracellular signaling to modulate various processes. Among the signalers is calcium, capable of acting in processes ranging from exocytosis to cell proliferation by increasing or decreasing its intracellular concentration. However, the homeostasis must be maintained, as high concentrations of calcium maintained for a long time cause apoptosis of the cell (Berridge, 2001; Berridge et al., 2003). The Plasmodium falciparum strain obtained by the knockout of the Protein Kinase 7 (PfPK7) gene is unable to feel the microenvironment as the wild parasite, not responding to melatonin stimuli and, therefore, unable to obtain a synchronous cycle (Koyama et al, 2012 ). For this reason, this strain becomes a great tool for signal transduction studies that alter the progression of the parasite cycle. It is known that the parasite’s mitochondria is capable of reversibly accumulating part of the calcium in the cytoplasm, thus participating in maintaining the homeostasis of this ion in the parasite and ensuring cell survival. (Gazarini; Garcia. 2004). The P. falciparum mitochondria has unusual evolutionary and functional characteristics, since the electron transport chain (CTE) is not its main source of ATP, and so far only three CTE proteins encoded by the mitochondrial genome have been identified, and some fragments of ribosomal RNA (Vaidya; Mather. 2009). Despite this, CTE inhibitors, such as the antimalarial atovaquone, proved to be lethal for the development of the parasite and, therefore, this organelle must participate in vital physiological processes in Plasmodium falciparum (Painter et al. 2007). In this context, this project highlights the importance of studying the role of mitochondria in the cell division and signaling mechanisms of Plasmodium falciparum during schizogony. In addition, the number and morphology of mitochondria will be analyzed and related to the expression of these proteins in these two strains, using chemiluminescence and microscopy techniques, at all stages of the parasite’s development in the presence and absence of Ca2 + stimuli.

Project details

Basic Science

Jun 2016 — Oct 2017

Brazil