Exosomes go with the Wnt

Exosomes, small secreted microvesicles, are implicated in intercellular communication in diverse cell types, transporting protein, lipid and nucleic acid cargo that impact the physiology of recipient cells. Besides the signaling function of exosomes they also serve as a mechanism to dispose obsolete cellular material.(1) Particularly exciting is the involvement of exosomal communication in the nervous system, as this has important implications for brain development and function. The properties of exosomes are also beginning to entice the biomedical community since they represent potentially novel avenues for the targeted delivery of customized exosome cargo, such as miRNAs, during disease. Our findings implicating exosomes in trans-synaptic communication emerged from the serendipitous observation that at the Drosophila larval neuromuscular junction (NMJ) the release of a signaling molecule, Wnt1/Wingless (Wg) and its binding partner Evenness Interrupted (Evi)/Wntless (Wls)/Sprint (Srt), were released by motorneurons in association with vesicles, which we postulated to be exosomes.(2) In our most recent paper(3) using in vivo analysis at the Drosophila NMJ as well as in cultured insect cells we formally demonstrate that Evi rides in exosomes that are released to the extracellular space and identify some of the players involved in their release. In addition, a proteomic analysis of exosomes highlights novel potential function of exosomes.