Abstract 14298: Circulating miRNA Transport Modality is Altered in Subjects with CHD with Implications for Endothelial Cell microRNA Uptake
MicroRNAs (miRNAs) are non-coding RNAs that regulate gene expression. The discovery of extracellular, circulating miRNAs and the finding that circulating miRNAs can be taken up by recipient cells, suggests an additional role for these molecules in mediating intercellular signaling events. Distinct transport modalities for circulating miRNAs govern the ability of extracellular miRNAs to be taken up by recipient cells with subsequent impact on cell function. We hypothesized that a homeostatic circulating miRNA transport profile exists in healthy subjects and that CHD is associated with an alteration to this profile which, in turn, impacts miRNA uptake. We analyzed the extracellular transport modalities of 8 miRNAs whose circulating levels are known to be altered in CHD: miR-17, -19a, -21, -92a, -126, -146a, -222, -223. Using an ultracentrifugation technique, sera from healthy subjects and subjects with significant CHD (n = 20 per group) were separated into apoptotic bodies/microvesicles, exosomes, aggregated protein, and lipoprotein fractions, respectively. The relative miRNA abundance in each fraction was quantified by qRT-PCR. In the sera of healthy subjects, there were miRNA-specific transport profiles that were independent of age and gender. For example, miR-126 was predominantly vesicular, with > 75% residing in the apoptotic body/microvesicle fraction. In subjects with CHD, the extracellular transport modality was shifted for 6 out of the 8 miRNAs assessed, with an approximate 20-30% decrease in miRNA abundance primarily observed in the microvesicular/apoptotic body fraction. Lastly, in vitro studies of HUVEC cells exposed to different fractions of human sera indicated that the apoptotic body/microvesicle fraction was most efficient at mediating the transfer of extracellular miRNA to cultured cells. In conclusion, CHD-associated shifts in extracellular miRNA transport modalities could underscore abnormalities in the intercellular transport of miRNA that contribute to endothelial cell dysfunction and CHD development. These data suggest that miRNA transport modality could be an important factor in the development of circulating miRNAs as biomarkers for disease and potential therapeutic targets.
- © 2012 by American Heart Association, Inc.