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To be or not to be... secreted as exosomes, a balance finely tuned by the mechanisms of biogenesis
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Edité par CCSD ; Portland Press -
International audience. The release of extracellular vesicles such as exosomes provides an attractive intercellular communication pathway. Exosomes are 30-150 nm membrane vesicles that originate in endosomal compartment and act as intercellular mediators in both physiological and pathological context. Despite of the growing interest in exosome functions, the mechanisms responsible for their biogenesis and secretion are still not completely understood. This knowledge is yet capital as it controls the composition, and hence the function, and the secretion of exosomes. Exosomes are produced as intraluminal vesicles (ILVs) in very dynamic endosomal organelles that undergo various maturation processes in order to form multivesicular endosomes. The function of multivesicular endosomes will notably be balanced between exosome secretion and lysosomal degradation. In this review, we present and discuss each intracellular trafficking pathways that have been reported or proposed to regulate exosomes biogenesis with a particular focus on the importance of endosomal dynamics in the sorting of protein cargoes to exosomes and the secretion of multivesicular endosomes. A global picture reveals several key mechanisms that act mainly at crossroads of endosomal pathways acting as regulatory checkpoints of exosome biogenesis. Summary Points: