Abstract

Biogenesis of RNA-containing Extracellular Vesicles

Alissa Weaver, Cornelius Vanderbilt Professor of Cell and Developmental Biology, Vanderbilt University Medical Center

Extracellular RNAs (exRNAs) carried by extracellular vesicles (EVs) can affect gene expression, function, and phenotypes of recipient cells. While a number of RNA binding proteins (RBPs) are known to carry RNAs into extracellular vesicles (EVs), where and how in the cell this occurs is unclear. As many RBP-RNA complexes are associated with the endoplasmic reticulum, we investigated whether membrane contact sites (ER MCS) with endosomes may drive the biogenesis of RNA-containing EVs.  To carry out this study, we used RNA-sequencing, lipidomic, confocal and transmission electron microscopy, tumor xenograft and various biochemical techniques to analyze EV biogenesis and cargo content in colon cancer cell lines molecularly engineered for molecules that control ER MCS. We uncovered a novel pathway of EV biogenesis that takes place at ER MCS. Our data suggest a model in which lipid transfer at ER MCS drives biogenesis of a select subpopulation of EVs containing RNA-RBP complexes. Beyond improving our understanding of EV biogenesis, we anticipate that these findings may be useful for future engineering of therapeutic EVs as well as exploring the functions of RNA-containing EVs.