TNF‐α alters the release and transfer of miRNAs from endothelial cells (711.7)

Abstract

MicroRNAs (miRNAs) encapsulated within extracellular vesicles likely have a role in cell‐to‐cell signaling, but little is known as to the mechanisms by which different cell types release miRNAs. Here, we examined the release and transfer of miR‐126, miR‐21, and miR‐155 in microparticles (MPs) produced by human aortic endothelial cells (ECs) treated with TNF舉α. ECs were treated with TNF‐α (100 ng/ml), in the presence or absence of inhibitors targeting distinct MP production pathways. MPs isolated from media were assessed by flow cytometry (count) and qRT‐PCR (miRNA content). Calcein AM‐labeled MPs were used to assess uptake by recipient ECs. TNF舉α induced a 5‐fold increase in MP production after 12‐24 hours of treatment (n = 5, p < 0.05). These MPs were characterized by: 1) 70 ‐ 80% decrease in the miRNA/MP levels for miR‐126 and ‐21 but 20‐fold increase in pre‐miR‐155 (n = 10, p < 0.05); 2) 50% reduction in uptake by recipient cells (n = 3, p < 0.05); and 3) inability to transfer miR‐126 and ‐21. Co‐treatment of donor ECs with TNF舉α and caspase inhibitor (Q‐VD‐OPH; 10μM) completely abrogated TNF舉α‐induced increase in MP number, and produced MPs that had: 1) increased uptake by recipient cells; 2) enhanced miRNA/MP content; and 3) increased ability to transfer miRNA. Co‐treatment of ECs with TNF舉α and Rho‐associated kinase (ROCK) inhibitor (10 μM) produced MPs similar to those produced by TNF舉α treatment alone. Overall, our data suggest that TNF舉α induces EC release of distinct MP populations: ROCK‐dependent, miRNA‐rich MPs that can transfer their miRNA contents to recipient cells, and caspase‐dependent, miRNA‐poor MPs that do not readily transfer their contents. These data provide insight into the relationship between MP production and extracellular release of miRNA, as well as the potential of encapsulated miRNA for information transfer.Grant Funding Source: Supported by NHLBI R01 and VA Merit Award