NPM1 Mediates mRNA Sorting into Extracellular Vesicles via Specific RNA Motif Binding and Phase Separation.

Extracellular vesicles (EVs) deliver genetic material to recipient cells, thereby influencing immunity, development, and various diseases. However, the precise mechanism by which specific mRNAs are selected for packaging into EVs remains poorly understood. This study identifies Nucleophosmin 1 (NPM1) as a key protein responsible for sorting mRNAs into EVs. NPM1 achieves this by binding to specific RNA motifs, including those within mRNAs such as the epidermal growth factor receptor (EGFR), thereby initiating the formation of phase separation condensates containing intracellular RNA. These condensates are subsequently packaged into late endosomes and multivesicular bodies, facilitating their loading into EVs. Additionally, EVs derived from the serum of non-small cell lung cancer (NSCLC) patients exhibit elevated levels of NPM1 protein and EGFR mRNA, suggesting relevance for this transportation mechanism to NSCLC pathogenesis. This study, therefore, not only enhances the understanding of the molecular mechanism underlying mRNA sorting into EVs but also provides valuable insights for potential therapeutic strategies targeting NSCLC.