Effect of plasmodial RESA protein on deformability of human red blood cells harboring Plasmodium falciparum

Abstract

During intraerythrocytic development, Plasmodium falciparum exports proteins that interact with the host cell plasma membrane and subplasma membrane-associated spectrin network. Parasiteexported proteins modify mechanical properties of host RBCs, resulting in altered cell circulation. In this work, optical tweezers experiments of cell mechanical properties at normal physiological and febrile temperatures are coupled, for the first time, with targeted gene disruption techniques to measure the effect of a single parasite-exported protein on host RBC deformability. We investigate Pf155/Ring-infected erythrocyte surface antigen (RESA), a parasite protein transported to the host spectrin network, on deformability of ring-stage parasite-harboring human RBCs. Using a set of parental, gene-disrupted, and revertant isogenic clones, we found that RESA plays a major role in reducing deformability of host cells at the early ring stage of parasite development, but not at more advanced stage. We also show that the effect of RESA on deformability is more pronounced at febrile temperature, which ring-stage parasite-harboring RBCs can be exposed to during a malaria attack, than at normal body temperature. malaria ͉ erythrocyte ͉ membrane shear modulus ͉ spectrin ͉ cytoskeleton A fter Plasmodium falciparum merozoite invasion of a human RBC, the parasite differentiates and multiplies for 48 h, leading to rupture of the parasitized RBC (Pf-RBCs) and release of new merozoites in the blood circulation. Throughout this 48-h period, several parasite proteins are introduced into the RBC plasma membrane and submembranous protein skeleton, thereby modifying a range of structural and functional properties of the Pf-RBCs (1-4). The best documented changes occur as P. falciparum matures to the trophozoite (24-36 h) and schizont (36-48 h) stages, when Pf-RBCs display decreased membrane deformability (2-6), become spherical, and develop cytoadherence properties responsible for parasite sequestration in the postcapillary venules of different organs (7,8). In contrast, during early parasite development, ring-stage (0-24 h after invasion) Pf-RBCs preserve their biconcave shape, can circulate in peripheral blood (9), and thus are exposed to the spleen red pulp. Ring-stage Pf-RBCs may pass through this spleen compartment, be expelled from circulation, or return to the circulation once the parasite has been removed (10). Although the relative importance of these different processes and their underlying mechanisms are not fully understood, it is likely that altered deformability of ring-stage Pf-RBCs (11) plays a crucial role in determining Pf-RBCs spleen processing.Introduction of parasite components within the Pf-RBC membrane and cortical cytoskeleton begins soon after RBC invasion, as demonstrated for the well characterized parasite protein Pf155/Ring-infected erythrocyte surface antigen (RESA) (12). This protein is discharged by the invading merozoite and exported to the Pf-RBC membrane where, once phosphorylated, it interacts with the spectrin n...

The transcriptome of Plasmodium vivax reveals divergence and diversity of transcriptional regulation in malaria parasites

“…Variation in the development of the PV, because of the delay of exp and etramp gene expression, might contribute to differences in erythrocyte modifications and lead to the observed differences in rigidity and cytoadherence between P. vivax and P. falciparum infected erythrocytes (12). Consistent with the differences in rigidity and cytoadherance properties between the two Plasmodium species is the observation that P. vivax lacks the genes of the ring-infected erythrocyte surface antigen (resa) family whose function is linked with the increased rigidity of P. falciparum infected erythrocytes (29). RESA proteins were found to be transported to the erythrocytic cytoskeleton via distinct compartments of the PV immediately after invasion (30).…”

“…correlate gene expression data in TP1-9 in P. vivax to the expression data in TP 9,13,17,20,23,29,35,40, and 43 in the P. falciparum transcriptome (Fig. S2).…”

Measurement Techniques for Red Blood Cell Deformability: Recent Advances

“…Optical tweezers technique measured that membrane shear modulus continuously increases as the disease progesses during the intraerythrocytic cycle (Suresh, Spatz et al,2005). Employing genetic knock-out assay, the effects of RESA protein to the host RBC deformabiltiy has been studied (Mills, Diez-Silva et al,2007). Membrane fluctuation measurement also showed increased shear modulus of malaria-invaded RBCs (Park, Diez-Silva et al,2008).…”

“…More interestingly, bimodal distributions in the values for µ were observed in independently reported data (Lenormand, Hénon et al, 2001;, suggesting the nonlinear stiffening of spectrin network . Malaria invasion cause significant increases in shear moduli values (Mills, Diez-Silva et al,2007).…”

Analysis of Hematocrit Variation Induced by Malaria-infected Red Blood Cells

“…Parasitic-derived proteins change the cell membrane and cytoskeleton [1,2], making the plasmodium falciparum-infected red blood cells (Pf-IRBCs) become more rigid than healthy red blood cells (HRBCs), and reduce the deformability of HRBCs [3,4]. The altered blood rheological properties, increased flow resistance, and occluded blood vessels may be due to the alternation of the biomechanical properties of the Pf-IRBCs [5].…”