TNF-α alters the release and transfer of microparticle-encapsulated miRNAs from endothelial cells

TNF-alpha alters the release and transfer of microparticle-encapsulated miRNAs from endothelial cells. Physiol Genomics 46: 833-840, 2014. First published October 14, 2014; doi: 10.1152/physiolgenomics. 00079.2014.-MicroRNAs (miRNAs) encapsulated within microparticles (MPs) are likely to have a role in cell-to-cell signaling in a variety of diseases, including atherosclerosis. However, little is known about the mechanisms by which different cell types release and transfer miRNAs. Here, we examined TNF-alpha-induced release of MPencapsulated miR-126, miR-21, and miR-155 from human aortic endothelial cells (ECs) and their transfer to recipient cells. ECs were treated with TNF-alpha (100 ng/ml) in the presence or absence of inhibitors that target different MP production pathways. MPs released in response to TNF-alpha were characterized by: 1) 70 -80% decrease in miRNA/MP levels for miR-126 and -21 but a significant increase in pre-miR-155 and miR-155 (P < 0.05), 2) 50% reduction in uptake by recipient cells (P < 0.05), and 3) diminished ability to transfer miRNA to recipient cells. Cotreatment of donor ECs with TNF-alpha and caspase inhibitor (Q-VD-OPH, 10 mu M) produced MPs that had: 1) 1.5-to 2-fold increase in miRNA/MP loading, 2) enhanced uptake by recipient cells (2-fold), and 3) increased ability to transfer miR-155. Cotreatment of ECs with TNF-alpha and Rho-associated kinase (ROCK) inhibitor (10 mu M) produced MPs with features similar to those produced by TNF-alpha treatment alone. Our data indicate that TNF-alpha induced the production of distinct MP populations: ROCK-dependent, miRNA-rich MPs that effectively transferred their cargo and were antiapoptotic, and caspase-dependent, miRNA-poor MPs that were proapoptotic. These data provide insight into the relationship between MP production and extracellular release of miRNA, as well as the potential of encapsulated miRNA for cell-to-cell communication.