RNA transfer via extracellular vesicles (EVs) influences cell phenotypes; however, lack of information regarding biogenesis of RNA-containing EVs has limited progress in the field. Vanderbilt University School of Medicine researchers have identified endoplasmic reticulum membrane contact sites (ER MCSs) as platforms for the generation of RNA-containing EVs. The researchers identified a subpopulation of small EVs that is highly enriched in RNA and regulated by the ER MCS linker protein VAP-A. Functionally, VAP-A-regulated EVs are critical for miR-100 transfer between cells and in vivo tumor formation. Lipid analysis of VAP-A-knockdown EVs revealed reductions in the EV biogenesis lipid ceramide. Knockdown of the VAP-A-binding ceramide transfer protein CERT led to similar defects in EV RNA content. Imaging experiments revealed that VAP-A promotes luminal filling of multivesicular bodies (MVBs), CERT localizes to MVBs, and the ceramide-generating enzyme neutral sphingomyelinase 2 colocalizes with VAP-A-positive ER. The researchers propose that ceramide transfer via VAP-A-CERT linkages drives the biogenesis of a select RNA-containing EV population.
VAP-A and its binding partner CERT drive biogenesis of RNA-containing extracellular vesicles
Barman B, Sung BH, Krystofiak E, Ping J, Ramirez M, Millis B, Allen R, Prasad N, Chetyrkin S, Calcutt MW, Vickers K, Patton JG, Liu Q, Weaver AM. (2022) VAP-A and its binding partner CERT drive biogenesis of RNA-containing extracellular vesicles at ER membrane contact sites. Dev Cell 57(8):974-994.e8. [article]