Effects of Mettl3 and Alkbh5 knockdown on small RNA export into EVs

Understanding the functional role of RNA modifications and to what extent they might regulate mature miRNA function and their secretion in extracellular vesicles (EVs) is unknown. Analysis of RNA content across a variety of EVs has shown differential miRNA enrichment when compared to parental cell expression patterns. Whether this is due to differential stability, specific regulation of miRNA export, or other mechanisms is unclear. Here, we tested whether RNA base modifications and recognition of those modifications might underlie differential miRNA export into EVs derived from KRAS mutant cell lines. We found that decreased levels of Mettl3, a writer of N6-methyladenosine (m6A) modification, altered extracellular transfer of miRNAs containing consensus sequences for m6A. Further, EVs prepared from cells expressing shRNAs against Mettl3 were incapable of conferring colony growth in 3D to wild type KRAS cells. Our data indicate that m6A modification plays an important role in miRNA export to EVs. RNAseq analysis of parental and knockdown cellular and EV RNA samples. There were 18 total samples, 9 cellular and 9 EV.