Extracellular ATP triggers proteolysis and cytosolic Ca²? rise in Plasmodium berghei and Plasmodium yoelii malaria parasites.

ABSTRACT:

Background

Plasmodium has a complex cell biology and it is essential to dissect the cell-signalling pathways underlying its survival within the host.

Methods

Using the fluorescence resonance energy transfer (FRET) peptide substrate Abz-AIKFFARQ-EDDnp and Fluo4/AM, the effects of extracellular ATP on triggering proteolysis and Ca²? signalling in Plasmodium berghei and Plasmodium yoelii malaria parasites were investigated.

Results

The protease activity was blocked in the presence of the purinergic receptor blockers suramin (50 ?M) and PPADS (50 ?M) or the extracellular and intracellular calcium chelators EGTA (5 mM) and BAPTA/AM (25, 100, 200 and 500 ?M), respectively for P. yoelii and P. berghei. Addition of ATP (50, 70, 200 and 250 ?M) to isolated parasites previously loaded with Fluo4/AM in a Ca²?-containing medium led to an increase in cytosolic calcium. This rise was blocked by pre-incubating the parasites with either purinergic antagonists PPADS (50 ?M), TNP-ATP (50 ?M) or the purinergic blockers KN-62 (10 ?M) and Ip5I (10 ?M). Incubating P. berghei infected cells with KN-62 (200 ?M) resulted in a changed profile of merozoite surface protein 1 (MSP1) processing as revealed by western blot assays. Moreover incubating P. berghei for 17 h with KN-62 (10 ?M) led to an increase in rings forms (82% ± 4, n = 11) and a decrease in trophozoite forms (18% ± 4, n = 11).

Conclusions

The data clearly show that purinergic signalling modulates P. berghei protease(s) activity and that MSP1 is one target in this pathway.

SUBMITTER: Cruz LN 

PROVIDER: S-EPMC3358241 | biostudies-literature | 2012 Mar

REPOSITORIES: biostudies-literature