title: Selective extracellular vesicle-mediated export of an overlapping set of microRNAs from multiple cell types.
abstract: BACKGROUND
  MicroRNAs (miRNAs) are a class of small RNA molecules that regulate expression of specific mRNA targets. They can be released from cells, often encapsulated within extracellular vesicles (EVs), and therefore have the potential to mediate intercellular communication. It has been suggested that certain miRNAs may be selectively exported, although the mechanism has yet to be identified. Manipulation of the miRNA content of EVs will be important for future therapeutic applications. We therefore wished to assess which endogenous miRNAs are enriched in EVs and how effectively an overexpressed miRNA would be exported.
  
  
  RESULTS
  Small RNA libraries from HEK293T cells and vesicles before or after transfection with a vector for miR-146a overexpression were analysed by deep sequencing. A subset of miRNAs was found to be enriched in EVs; pathway analysis of their predicted target genes suggests a potential role in regulation of endocytosis. RT-qPCR in additional cell types and analysis of publicly available data revealed that many of these miRNAs tend to be widely preferentially exported. Whilst overexpressed miR-146a was highly enriched both in transfected cells and their EVs, the cellular:EV ratios of endogenous miRNAs were not grossly altered. MiR-451 was consistently the most highly exported miRNA in many different cell types. Intriguingly, Argonaute2 (Ago2) is required for miR-451 maturation and knock out of Ago2 has been shown to decrease expression of other preferentially exported miRNAs (eg miR-150 and miR-142-3p).
  
  
  CONCLUSIONS
  The global expression data provided by deep sequencing confirms that specific miRNAs are enriched in EVs released by HEK293T cells. Observation of similar patterns in a range of cell types suggests that a common mechanism for selective miRNA export may exist.
authors: Centre for Vision and Vascular Science, Queen's University Belfast, Northern Ireland, UK.
authors: Jasenka
authors: J
authors: Guduric-Fuchs
authors: Anna
authors: A
authors: O'Connor
authors: Bailey
authors: B
authors: Camp
authors: Christina L
authors: CL
authors: O'Neill
authors: Reinhold J
authors: RJ
authors: Medina
authors: David A
authors: DA
authors: Simpson
mesh_terms: D060565:Argonaute Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D002460:Cell Line; D004705:Endocytosis / Q000235:genetics*; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism*; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D005822:Genetic Vectors; D057809:HEK293 Cells; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D012333:RNA, Messenger / Q000235:genetics*; D014162:Transfection; D022161:Transport Vesicles / Q000378:metabolism*
chemical_list: C466422:AGO2 protein, human; D060565:Argonaute Proteins; D035683:MicroRNAs; D012333:RNA, Messenger