Poster Presentation Australasia Extracellular Vesicles Conference 2017

An endogenous retroviral noncoding RNA is highly enriched in exosomes and transferred to recipient cells both in vitro and in vivo (#41)

Marilou H Barrios 1 2 3 , Alexandra Garnham 4 , Matthew Wakefield 4 , Benjamin Scicluna 5 6 , Nick Huntington 2 7 , Seth Masters 1 2 , Ken Pang 1 3 8 9
  1. Inflammation, Walter and Eliza Hall Institute of Medical Research (WEHI), Parkville, Victoria, Australia
  2. Medical Biology, University of Melbourne, Parkville, Victoria, Australia
  3. Neurodevelopmental Genomics Research, Murdoch Children's Research Institute, Parkville, Victoria, Australia
  4. Bioinformatics, Walter and Eliza Hall Institute of Medical Research (WEHI), Parkville, Victoria, Australia
  5. Medicine, Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria, Australia
  6. Biochemistry and Genetics, La Trobe University, La Trobe Institue for Molecular Sciences, Bundoora, Victoria, Australia
  7. Molecular Immunology, Walter and Eliza Hall Institute of Medical Research (WEHI), Parkville, Victoria, Australia
  8. Paediatrics, University of Melbourne, Parkville, Victoria, Australia
  9. Psychiatry, University of Melbourne, Parkville, Victoria, Australia

There is increasing interest in intercellular communication via RNA transfer. However, there is minimal evidence for such communication in vivo. To explore this issue, we initially profiled exosomal RNAs from mouse dendritic cells (DCs) using RNAseq, and identified 230 RNAs that were specifically enriched in exosomes. Of these, the RNA that showed the greatest enrichment in exosomes (~200-fold) and was also the third most abundant exosomal RNA was a long noncoding RNA (lncRNA) derived from a mouse-specific endogenous retrovirus known as VL30. Using qRT-PCR, we confirmed the strong exosomal enrichment of the VL30 lncRNA in not only mouse dendritic cells but also macrophages, T cells, B cells and fibroblasts. Next, we tested whether the VL30 lncRNA could be transferred to recipient cells in vitro by co-culturing DC-derived exosomes with either immortalised human B cells (Raji) or cancer cells (HeLa) whose genomes lack VL30 orthologs.  In each case, we found evidence of VL30 lncRNA transfer from the exosomes. Finally, to determine whether VL30 lncRNA can be transferred to recipient cells in vivo, we generated humanized mice and assessed whether VL30 lncRNA can be found in human B cells. Strikingly, VL30 was readily detected in human B cells from these mice, indicating that VL30 is also transferred in vivo. Taken together, this work suggests that VL30 lncRNA is being selectively loaded into exosomes and subsequently transferred to recipient cells. How this selective loading occurs and the functional consequences of VL30 lncRNA transfer are now being investigated.