Nontemplated Nucleotide Additions Distinguish the Small RNA Composition in Cells from Exosomes

Functional biomolecules, including small noncoding RNAs (ncRNAs), are released and transmitted between mammalian cells via extracellular vesicles (EVs), including endosome-derived exosomes. The small RNA composition in cells differs from exosomes, but underlying mechanisms have not been established.

Researchers from the VU University Medical Center, the Netherlands generated small RNA profiles by RNA sequencing (RNA-seq) from a panel of human B cells and their secreted exosomes. A comprehensive bioinformatics and statistical analysis revealed nonrandomly distributed subsets of microRNA (miRNA) species between B cells and exosomes. Unexpectedly, 3′ end adenylated miRNAs are relatively enriched in cells, whereas 3′ end uridylated isoforms appear overrepresented in exosomes, as validated in naturally occurring EVs isolated from human urine samples. Collectively, these findings suggest that posttranscriptional modifications, notably 3′ end adenylation and uridylation, exert opposing effects that may contribute, at least in part, to direct ncRNA sorting into EVs.

exosome rna

Koppers-Lalic D, Hackenberg M, Bijnsdorp IV, van Eijndhoven MA, Sadek P, Sie D, Zini N, Middeldorp JM, Ylstra B, de Menezes RX, Würdinger T, Meijer GA, Pegtel DM. (2014) Nontemplated Nucleotide Additions Distinguish the Small RNA Composition in Cells from Exosomes. Cell Rep [Epub ahead of print]. [article]

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