Functional analysis of the essential red blood cell Basigin in Plasmodium falciparum invasion

Malaria is a deadly infectious disease that can cause dramatic cardiovascular complications. Plasmodium falciparum is the principal malaria pathogen and its replication within red blood cells (RBCs) causes the pathogenesis of the disease. The first and crucial step towards RBC infection is parasite invasion which requires the attachment of the parasite to specific RBC surface receptors. Malaria is a strong selective pressure on human evolution that has shaped the RBC proteome and blood group phenotypes, inducing host polymorphisms that confer resistance to P. falciparum invasion and development. The OK blood group antigen Basigin (BSG) plays pivotal roles in cellular signaling and in numerous physiological processes. It is also the functional entry receptor for several infectious agents and a critical erythrocyte receptor indispensable for P. falciparum invasion. Rare BSG polymorphisms only enriched for in malaria-exposed populations may reduce host susceptibility to invasion. We propose to investigate these polymorphisms to identify specific residues on BSG that are dispensable for its physiological function but critical for parasite invasion. In our first Aim, we identified BSG polymorphisms, enriched in malaria-endemic regions, and performed structure/function analysis to identify SNPs susceptible to alter ligand-receptor interactions. Next, we will use a site-directed mutagenesis approach to interrogate the effect of these polymorphisms on P. falciparum invasion and erythroid functions. These critical residues may be therapeutically targeted to prevent infection. Although BSG forms complexes with different membrane proteins in other cell types, it is unclear whether it interacts with RBC membrane partners within a complex to facilitate P. falciparum entry. In our second Aim, we propose to identify additional host factors that influence invasion through modulating BSG function, by identifying proteins that complex with BSG, and through a functional screen of RBCs with rare null blood group phenotypes to identify synergistic receptors. Candidate molecules will be validated using a CRISPR/Cas9 approach to produce loss-of-function in vitro cultured erythrocyte mutants and measuring P. falciparum invasion. Modulation of BSG function will be assessed by measuring the effect of loss-of-function on a) BSG trafficking, (b) expression and (c) complex formation. This will help identify potential therapeutic targets to enhance an anti-BSG therapy.

Basic Science

Jan 2023 — Dec 2024

$143,177

United States