title: New antimalarial indolone-N-oxides, generating radical species, destabilize the host cell membrane at early stages of Plasmodium falciparum growth: role of band 3 tyrosine phosphorylation.
abstract: Although indolone-N-oxide (INODs) genereting long-lived radicals possess antiplasmodial activity in the low-nanomolar range, little is known about their mechanism of action. To explore the molecular basis of INOD activity, we screened for changes in INOD-treated malaria-infected erythrocytes (Pf-RBCs) using a proteomics approach. At early parasite maturation stages, treatment with INODs at their IC(50) concentrations induced a marked tyrosine phosphorylation of the erythrocyte membrane protein band 3, whereas no effect was observed in control RBCs. After INOD treatment of Pf-RBCs we also observed: (i) accelerated formation of membrane aggregates containing hyperphosphorylated band 3, Syk kinase, and denatured hemoglobin; (ii) dose-dependent release of microvesicles containing the membrane aggregates; (iii) reduction in band 3 phosphorylation, Pf-RBC vesiculation, and antimalarial effect of INODs upon addition of Syk kinase inhibitors; and (iv) correlation between the IC(50) and the INOD concentrations required to induce band 3 phosphorylation and vesiculation. Together with previous data demonstrating that tyrosine phosphorylation of oxidized band 3 promotes its dissociation from the cytoskeleton, these results suggest that INODs cause a profound destabilization of the Pf-RBC membrane through a mechanism apparently triggered by the activation of a redox signaling pathway rather than direct oxidative damage.
authors.affiliation: Department of Physiological, Biochemical, and Cell Sciences, University of Sassari, Sassari 07100, Italy. apantaleo@uniss.it
authors.forename: Antonella
authors.initials: A
authors.lastname: Pantaleo
authors.forename: Emanuela
authors.initials: E
authors.lastname: Ferru
authors.forename: Rosa
authors.initials: R
authors.lastname: Vono
authors.forename: Giuliana
authors.initials: G
authors.lastname: Giribaldi
authors.forename: Omar
authors.initials: O
authors.lastname: Lobina
authors.forename: Françoise
authors.initials: F
authors.lastname: Nepveu
authors.forename: Hany
authors.initials: H
authors.lastname: Ibrahim
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Nallet
authors.forename: Franco
authors.initials: F
authors.lastname: Carta
authors.forename: Franca
authors.initials: F
authors.lastname: Mannu
authors.forename: Proto
authors.initials: P
authors.lastname: Pippia
authors.forename: Estela
authors.initials: E
authors.lastname: Campanella
authors.forename: Philip S
authors.initials: PS
authors.lastname: Low
authors.forename: Francesco
authors.initials: F
authors.lastname: Turrini
mesh_terms: D001457:Anion Exchange Protein 1, Erythrocyte / Q000378:metabolism*; D000962:Antimalarials / Q000494:pharmacology*; D002462:Cell Membrane / Q000187:drug effects* / Q000378:metabolism; D003497:Cyclic N-Oxides / Q000494:pharmacology*; D004912:Erythrocytes / Q000187:drug effects / Q000378:metabolism / Q000469:parasitology; D005260:Female; D005609:Free Radicals / Q000737:chemistry*; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D016778:Malaria, Falciparum / Q000469:parasitology*; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism*; D010963:Plasmodium falciparum / Q000187:drug effects / Q000254:growth & development*; D055503:Protein Multimerization; D020543:Proteome / Q000378:metabolism
chemical_list: D001457:Anion Exchange Protein 1, Erythrocyte; D000962:Antimalarials; D003497:Cyclic N-Oxides; D005609:Free Radicals; D007211:Indoles; D008565:Membrane Proteins; D020543:Proteome; C454201:SLC4A1 protein, human; D019000:Phosphotyrosine