| description |
Despite clear evidence that exosomal microRNAs (miRNAs) are able to modulate the cellular microenvironment and that exosomal RNA cargo selection is often deregulated in pathological conditions, the mechanisms controlling specific RNA sorting into extracellular vescicles are still poorly understood. We identified here the RNA binding protein SYNCRIP (Synaptotagmin-binding Cytoplasmic RNA-Interacting Protein, also known as hnRNP-Q or NSAP1) as a component of the hepatocyte exosomal miRNA sorting machinery. SYNCRIP was found to bind directly a subset of miRNAs enriched in exosomes, sharing a common extra-seed sequence that we named hEXO motif. In vivo knock-down of SYNCRIP impaired microRNA sorting in exosomes and the hEXO motif was proven to play a role in the regulation of miRNA localization, as its embedment into a poorly exported miRNA enhanced its loading into exosomes. These results provide a new insight in the mechanisms of miRNA exosomal sorting process, that ca be exploited to further understand the role of these extracellular vescicles in cell-to-cell communications and the control of tissue micoenvironments. |