Characterization of apoptotic exosome-like vesicles (ApoExo) Biogenesis and Internalization
Our group demonstrated that, in addition to classical apoptotic bodies released through the budding of the cell membrane, caspase-3 activation triggers the release of apoptotic exosome-like vesicles (30 to 100nm) with strong immunogenic activity. These ApoExo lack usual markers of apoptotic bodies, such as histones and HMGB1, but carry functionally active 20S proteasome and perlecan∕LG3. They are produced following vascular injury and foster the production of anti-LG3 autoantibodies, which have been shown to aggravate ischemia-reperfusion injury and transplant rejection in animal models and transplant patients. Recently, our group identified autolysosomes as a site of ApoExo biogenesis and caspase-3 as a crucial regulator of autolysosome cell membrane interactions involved in the secretion of immunogenic ApoExo. We now aim to characterize the autophagy independent-pathways controlling the loading of other components (eg 20S proteasome) onto ApoExo.
ApoExo express patterns of mRNA and miRNA that differ from both apoptotic bodies and classical exosomes. We also showed that uptake of ApoExo by endothelial cells drives NF-κB activation leading to endothelial dedifferentiation. This research project aims to characterize the effective entry pathway for the delivery of mRNA and miRNA that are internalized and functionally expressed by uptaking endothelial cells. It will also characterize further the mechanisms by which ApoExo contribute to intercellular nucleic acid sharing to impact endothelial function and modify vascular homeostasis.