The RNA-binding protein hnRNPA2B1 inhibits the export of miR-503 into exosomes

Background: The exosomal export of the anti-tumoural miR-503 is positively regulated by the chemotherapeutic agent Epirubicin (Epi). The aim of this study is to determine the mechanism underlying this process. Methods: To determine the partners of miR-503, serial crosslinkings (CLs) were performed i...

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Bibliographic Details
Published in:Journal of extracellular vesicles 2018-01, Vol.7, p.114-114
Main Authors: Boza, Jennifer Perez, Boeckx, Amandine, Lion, Michelle, Struman, Ingrid
Format: Article
Language:English
Subjects:
Affinity
Biotin
Epirubicin
Exosomes
Immunoprecipitation
Mass spectrometry
Mass spectroscopy
miRNA
Protein transport
Proteins
RNA-binding protein
Scientific imaging
Western blotting
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Summary:Background: The exosomal export of the anti-tumoural miR-503 is positively regulated by the chemotherapeutic agent Epirubicin (Epi). The aim of this study is to determine the mechanism underlying this process. Methods: To determine the partners of miR-503, serial crosslinkings (CLs) were performed in HUVECs prior pulling down a synthetic miR503-biotin. The proteins associated to this microRNA were then identified by mass spectrometry and validated by western blotting (WB). Then, the effect of Epi on these putative partners was studied at gene and protein levels and the affinity of these proteins with miR-503 was determined using immunoprecipitation techniques. The role of these proteins in the export of miR-503 was assessed by a series of silencing experiments. Results: Nine different proteins were identified by mass spectrometry analysis and only five putative partners were validated by WB. While the treatment with Epi induced the expression of FN1, both the levels of hnRNPA2B1 and TSP1 were significantly reduced. Moreover, the treatment with the chemotherapeutic drug induced a significant increase in the export of ANXA2 into exosomes. Immunoprecipitation studies showed that hnRNPA2B1 has an important affinity for miR-503 and that the interaction of these partners with miR-503 is substantially reduced after treatment. Finally we found that the knock down of hnRNPA2B1 alone was able to reproduce the increase of exosomal miR-503 induced by the treatment with Epirubicin. Summary/Conclusion: Our data suggests that Epi mediates the export of miR-503 into exosomes via hnRNPA2B1 downregulation and subsequent complex destabilization. This study shows that hnRNPA2B1 has an active role in maintaining miR-503 inside the cell and thus inhibits its export into exosomes. Of note, for the first time, this work provides evidence that a RNA binding protein can play a negative role in the export of microRNAs into exosomes.
ISSN:2001-3078