Abstract:
Extracellular vesicles (EV) secreted by pathogens function in a variety of biological processes.
Here, we demonstrate that in the protozoan parasite Trypanosoma brucei, exosome
secretion is induced by stress that affects trans-splicing. Following perturbations in
biogenesis of spliced leader RNA, which donates its spliced leader (SL) exon to all mRNAs,
or after heat-shock, the SL RNA is exported to the cytoplasm and forms distinct granules,
which are then secreted by exosomes. The exosomes are formed in multivesicular bodies
(MVB) utilizing the endosomal sorting complexes required for transport (ESCRT), through a
mechanism similar to microRNA secretion in mammalian cells. Silencing of the ESCRT factor,
Vps36, compromised exosome secretion but not the secretion of vesicles derived from
nanotubes. The exosomes enter recipient trypanosome cells. Time-lapse microscopy demonstratedthat cells secreting exosomes or purified intact exosomes affect social motility
(SoMo). This study demonstrates that exosomes are delivered to trypanosome cells and
can change their migration. Exosomes are used to transmit stress signals for communicationbetween parasites.
