Host cell signalling and programmed cell death in Plasmodium liver stage prasites

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Universität Bern, Institut für Zellbiologie

There is clear evidence that Plasmodium parasites undergo a kind of programmed cell death (PCD). However, little is known about the molecular mechanisms that are responsible for such an event. Intracellular liver stage Plasmodium parasites are known to modulate PCD of their host cells but now it appears that MAP kinase signalling in the host cell interacts with parasite MAP kinase signalling to support survival of the pathogen. To analyse the molecular basis of PCD in Plasmodium, database searches for molecules involved in both apoptosis and autophagy, the two most common types of PCD, have been conducted on several Plasmodium species. Interestingly, the predicted proteomes of these parasites were found to lack molecules responsible for apoptosis, whereas proteins responsible for autophagic processes were identified. Plasmodium parasites undergo several dramatic reorganisations during their life cycle and it is plausible that they employ autophagy as a means to remove dispensable cellular material. It is reasonable to assume that during evolution, autophagy was additionally used to eliminate excess parasites or parasites that have not successfully entered a host cell, to avoid provoking strong inflammatory immune responses.