RESUMO
Mature red blood cells (RBCs) lack internal organelles and canonical defense mechanisms, making them both a fascinating host cell, in general, and an intriguing choice for the deadly malaria parasite Plasmodium falciparum (Pf), in particular. Pf, while growing inside its natural host, the human RBC, secretes multipurpose extracellular vesicles (EVs), yet their influence on this essential host cell remains unknown. Here we demonstrate that Pf parasites, cultured in fresh human donor blood, secrete within such EVs assembled and functional 20S proteasome complexes (EV-20S). The EV-20S proteasomes modulate the mechanical properties of naïve human RBCs by remodeling their cytoskeletal network. Furthermore, we identify four degradation targets of the secreted 20S proteasome, the phosphorylated cytoskeletal proteins ß-adducin, ankyrin-1, dematin and Epb4.1. Overall, our findings reveal a previously unknown 20S proteasome secretion mechanism employed by the human malaria parasite, which primes RBCs for parasite invasion by altering membrane stiffness, to facilitate malaria parasite growth.
Assuntos
Transporte Biológico/fisiologia , Eritrócitos/metabolismo , Interações Hospedeiro-Parasita/fisiologia , Malária Falciparum/metabolismo , Plasmodium falciparum/metabolismo , Complexo de Endopeptidases do Proteassoma/metabolismo , Citoesqueleto/metabolismo , Eritrócitos/citologia , Eritrócitos/parasitologia , Humanos , Malária Falciparum/parasitologia , Proteínas de Membrana/metabolismo , Fosforilação , Plasmodium falciparum/crescimento & desenvolvimento , ProteômicaRESUMO
Extracellular vesicles (EVs) are cell-derived membrane-bound structures that are believed to play a major role in intercellular communication by allowing cells to exchange proteins and genetic cargo between them. In particular, pathogens, such as the malaria parasite Plasmodium (P.) falciparum, utilize EVs to promote their growth and to alter their host's response. Thus, better characterization of these secreted organelles will enhance our understanding of the cellular processes that govern EVs' biology and pathological functions. Here we present a method that utilizes a high-end flow cytometer system to characterize small EVs, i.e., with a diameter less than 200 nm. Using this method, we could evaluate different parasite-derived EV populations according to their distinct cargo by using antibody-free labeling. It further allows to closely monitor a sub-population of vesicles carrying parasitic DNA cargo. This ability paves the way to conducting a more 'educated' analysis of the various EV cargo components.
