PLD2-phosphatidic acid recruit ESCRT-I to late endosomes for exosome biogenesis.

It is important to understand the biogenesis of exosomes, extracellular vesicles of endosomal origin controlling cell-to-cell communication. We previously reported that Phospholipase D2 (PLD2) supports late endosome (LE) budding and the biogenesis of syntenin-dependent exosomes. Here, we reveal that PLD2 has a broader generic effect on exosome production. Combining gain- and loss-of-function experiments, proteomics, microscopy and lipid-binding studies with reconstituted liposomes mimicking LE, we show that: (i) PLD2 activity controls the recruitment of MVB12B to LE and the exosomal secretion of ESCRT-I; (ii) loss-of-MVB12B phenocopies loss-of-PLD2, similarly affecting LE budding, the number of exosomes released and exosome loading with cargo; (iii) MVB12B MABP domain directly interacts with phosphatidic acid, the product of PLD2. We therefore propose that PLD2 and phosphatidic acid support ESCRT-I recruitment to LE for the formation of exosomes. This work highlights a major unsuspected piece of the molecular framework supporting LE and exosome biogenesis.