Dynamic RNA profiling in Plasmodium falciparum synchronized blood stages exposed to lethal doses of artesunate.
BACKGROUND
Translation of the genome sequence of Plasmodium sp. into biologically relevant information relies on high through-put genomics technology which includes transcriptome analysis. However, few studies to date have used this powerful approach to explore transcriptome alterations of P. falciparum parasites exposed to antimalarial drugs.


RESULTS
The rapid action of artesunate allowed us to study dynamic changes of the parasite transcriptome in synchronous parasite cultures exposed to the drug for 90 minutes and 3 hours. Developmentally regulated genes were filtered out, leaving 398 genes which presented altered transcript levels reflecting drug-exposure. Few genes related to metabolic pathways, most encoded chaperones, transporters, kinases, Zn-finger proteins, transcription activating proteins, proteins involved in proteasome degradation, in oxidative stress and in cell cycle regulation. A positive bias was observed for over-expressed genes presenting a subtelomeric location, allelic polymorphism and encoding proteins with potential export sequences, which often belonged to subtelomeric multi-gene families. This pointed to the mobilization of processes shaping the interface between the parasite and its environment. In parallel, pathways were engaged which could lead to parasite death, such as interference with purine/pyrimidine metabolism, the mitochondrial electron transport chain, proteasome-dependent protein degradation or the integrity of the food vacuole.


CONCLUSIONS
The high proportion of over-expressed genes encoding proteins exported from the parasite highlight the importance of extra-parasitic compartments as fields for exploration in drug research which, to date, has mostly focused on the parasite itself rather than on its intra and extra erythrocytic environment. Further work is needed to clarify which transcriptome alterations observed reflect a specific response to overcome artesunate toxicity or more general perturbations on the path to cellular death.
Natalang
Onguma
O
Institut Pasteur, Unité d'Immunologie Moléculaire des Parasites, CNRS URA 2581, 28 Rue du Docteur Roux, F-75724, Paris, Cedex 15, France. onguma382@yahoo.com
Bischoff
Emmanuel
E
Deplaine
Guillaume
G
Proux
Caroline
C
Dillies
Marie-Agnès
MA
Sismeiro
Odile
O
Guigon
Ghislaine
G
Bonnefoy
Serge
S
Patarapotikul
Jintana
J
Mercereau-Puijalon
Odile
O
Coppée
Jean-Yves
JY
David
Peter H
PH
D000704:Analysis of Variance; D000818:Animals; D000962:Antimalarials / Q000494:pharmacology*; D037621:Artemisinins / Q000494:pharmacology*; D000077332:Artesunate; D002478:Cells, Cultured; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects; D017125:Genes, Protozoan / Q000187:drug effects; D008018:Life Cycle Stages; D020411:Oligonucleotide Array Sequence Analysis; D010963:Plasmodium falciparum / Q000187:drug effects* / Q000235:genetics* / Q000254:growth & development; D016053:RNA, Protozoan / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors
D000962:Antimalarials; D037621:Artemisinins; D016053:RNA, Protozoan; D000077332:Artesunate